tag:blogger.com,1999:blog-47248383998308738862024-02-18T22:21:26.799-08:00Lucas TafurDiscusión en salud, nutrición y ciencia. Lucas Tafurhttp://www.blogger.com/profile/11675271094892394659noreply@blogger.comBlogger41125tag:blogger.com,1999:blog-4724838399830873886.post-10192969937833293072013-09-02T10:09:00.001-07:002017-03-13T06:07:40.192-07:00Updates<span style="font-family: Trebuchet MS, sans-serif;">I plan to re-start writing posts, but cant be sure when it is going to happen. Meanwhile, I will post papers that caught my interest in my facebook page as a way to encourage discussion. If anyone needs/wants the full text of a particular study, feel free to ask. </span><br />
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<span style="font-family: Trebuchet MS, sans-serif;">My mind is always expecting to learn and be fascinated by something new, so probably, the studies I will post are not only nutrition/immunology related. I have developed a great interest in sound perception and experience. Additionally, dont be surprised to find biophysics related stuff, which is my academic interest as well as my scope of research on the lab. </span><br />
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<span style="font-family: Trebuchet MS, sans-serif;">I would love that readers start sharing papers looking for discussion on the page. The best way to learn is discussing, which inherently implies that you have to read and (probably) learn something new in order to answer a particular question. This is why I love to teach. </span><br />
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<span style="font-family: Trebuchet MS, sans-serif;">You can access my facebook page clicking the link below:</span><br />
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<span style="font-family: Trebuchet MS, sans-serif;"><a href="https://www.facebook.com/pages/Lucas-Tafur/230045633723327?ref=hl" target="_blank">Facebook</a></span><br />
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<span style="font-family: 'Trebuchet MS', sans-serif;">Any news regarding the blog (new posts, etc) will be posted in there.</span><br />
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<span style="font-family: 'Trebuchet MS', sans-serif;">Hope to see you over there!</span>Anonymousnoreply@blogger.com5tag:blogger.com,1999:blog-4724838399830873886.post-64650407207703211312012-07-11T19:16:00.000-07:002017-03-13T06:07:40.211-07:00Nutritional immunotherapy: dietary fatty acids<div style="text-align: justify;">
<span style="font-family: 'Trebuchet MS', sans-serif;">Most people familiarized with a paleo-type lifestyle already know that a healthy diet should include good fats, rich in saturated (SFAs) and monounsaturated fatty acids (MUFAs). This profile is characteristic of animal fats. Conversely, intake of polyunsaturated fatty acids (PUFAs) should be limited. These recommendations are in accordance with the biological, chemical and evolutionary aspects of fatty acids in the human diet. We might see</span><span style="font-family: 'Trebuchet MS', sans-serif;"> this dietary fatty acid profile as a "natural" one. </span></div>
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<span style="font-family: 'Trebuchet MS', sans-serif;">As I stated in my <a href="http://www.lucastafur.com/2012/03/nutritional-immunotherapy-overview.html">last post</a>, I support the notion that some inflammatory/autoimmune disorders deserve a different approach, owing to the body's unnatural state. This deviation from normality implies that we cannot expect the same response to some nutritional components in diseased people. </span></div>
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<span style="font-family: 'Trebuchet MS', sans-serif;"><u>Background</u></span></div>
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<span style="font-family: 'Trebuchet MS', sans-serif;">For understanding the basis of my recommendations, we must review a little bit about Toll-like receptors (TLRs) and the classic cellular inflammatory cascade, the NFkB pathway. TLRs are pattern recognition receptors which bind pathogen associated molecular patterns (PAMPs). PAMPs are conserved molecular motifs found in a broad range of pathogens that are recognized by receptors mediating an innate-type immune response (like TLRs). PAMPs include LPS, lipoproteins, peptidoglycan, lipoteichoic acid and other molecules capable of binding to these receptors and trigger a response. There are different type of TLRs, with different cellular localizations and associated intracellular pathways, but most converge in the activation of <a href="http://en.wikipedia.org/wiki/NF-%CE%BAB" target="_blank">NFkB</a>. The final effect of ligand binding and protein signaling is the expression of inflammatory genes. </span><br />
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<span style="font-family: 'Trebuchet MS', sans-serif;">TLRs have evolved not only a function in immunity, but recent evidence suggests a pivotal role in metabolism. </span><br />
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<span style="font-family: 'Trebuchet MS', sans-serif;"><u>TLR4/MD-2 binds to LPS</u></span><br />
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<span style="font-family: 'Trebuchet MS', sans-serif;"><a href="http://en.wikipedia.org/wiki/Lipopolysaccharide" target="_blank">LPS</a>, the classic TLR ligand, binds and activates signaling through TLR4 (<a href="http://www.ncbi.nlm.nih.gov/pubmed/11278967" target="_blank">1</a>). This interaction is mediated by the lipid moiety, Lipid A. The toxicity of LPS is thought to be due to the interaction of TLR4 with Lipid A, and the shape and conformation of this lipid may determine the toxicity of a given pathogen (LPS are not created equal) (<a href="http://www.ncbi.nlm.nih.gov/pubmed/11864841" target="_blank">2</a>). The differences arise from the number and length of fatty acid chains. </span><br />
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<tr><td style="text-align: center;"><a href="http://4.bp.blogspot.com/-Rh_p1ifYFyA/T3x2udIy9-I/AAAAAAAAAGg/8lH6qDPlGDg/s1600/lipidA.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="88" src="http://4.bp.blogspot.com/-Rh_p1ifYFyA/T3x2udIy9-I/AAAAAAAAAGg/8lH6qDPlGDg/s400/lipidA.JPG" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">LPS general structure. Supplemental Material: Annu. Rev. Biochem. 2011. 80:917-941. <a href="http://www.annualreviews.org/article/suppl/10.1146/annurev-biochem-052909-141507?file=bi-80-lee.pdf" target="_blank">Link</a>.</td></tr>
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<span style="font-family: 'Trebuchet MS', sans-serif;">Typically, 4 to 7 lipid chains with 12 to 14 carbons of length are anchored to the glucosamine backbone. </span><br />
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<span style="font-family: 'Trebuchet MS', sans-serif;">For being able to recognize LPS, TLR4 binds <a href="http://en.wikipedia.org/wiki/MD-2_(immunology)" target="_blank">MD-2</a> and forms the complex responsible for the interaction. Only one third of MD-2 is involved in the interaction with TLR4 and the remaining part is available for interaction with other ligands. The presence of LPS is necessary for TLR4/MD-2 dimerization (<a href="http://www.ncbi.nlm.nih.gov/pubmed/21845181/" target="_blank">3</a>). </span><br />
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<tr><td style="text-align: center;"><a href="http://4.bp.blogspot.com/-gI1itzu_l_E/T3x9gfY3CVI/AAAAAAAAAGo/oRssOoJ-gCo/s1600/TLR4-MD2-LPS.bmp" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="224" src="http://4.bp.blogspot.com/-gI1itzu_l_E/T3x9gfY3CVI/AAAAAAAAAGo/oRssOoJ-gCo/s320/TLR4-MD2-LPS.bmp" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">TLR4/MD-2 complex. <a href="http://www.annualreviews.org/doi/pdf/10.1146/annurev-biochem-052909-141507" target="_blank">Annu. Rev. Biochem. 2011. 80:917-941</a>.
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<span style="font-family: 'Trebuchet MS', sans-serif;"></span><span style="font-family: 'Trebuchet MS', sans-serif;">Structural studies have proposed that certain factors determine the endotoxic activity of lipid A. </span><span style="font-family: 'Trebuchet MS', sans-serif;">The number of lipid chains seems to be the most important: Six lipid chains of 12 to 14 carbons each promote an optimal inflammatory activity. Because of this, the deletion of two lipid chains can destroy agonistic activity, making some LPS TLR4 antagonists (<a href="http://www.ncbi.nlm.nih.gov/pubmed/21548780" target="_blank">4</a>). The SFAs linked to the Lipid A backbone are 3-O-acylated by lauric acid, myristic acid or palmitic acid, which seem to be important for the immunological effects of LPS, given that their loss abolishes LPS endotoxic properties and produces an antagonist of Lipid A (<a href="http://www.ncbi.nlm.nih.gov/pubmed/1380063?dopt=Abstract" target="_blank">5</a>, <a href="http://www.ncbi.nlm.nih.gov/pubmed/7537270" target="_blank">6</a>). The logical inference of these facts is that these SFAs are important for the binding and/or LPS-induced TLR4 activation.</span><br />
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<span style="font-family: 'Trebuchet MS', sans-serif;">The role for TLR4 in metabolic abnormalities has been corroborated using animal models. Mice with a loss-of-function mutation in TLR4 or TLR4-null mice are protected against the development of diet-induced obesity and insulin resistance (<a href="http://www.ncbi.nlm.nih.gov/pubmed/17519423" target="_blank">7</a>, <a href="http://www.ncbi.nlm.nih.gov/pubmed/17426960" target="_blank">8</a>, <a href="http://www.ncbi.nlm.nih.gov/pubmed/17478729" target="_blank">9</a>). Deletion of CD14, a TLR2/TLR4 co-receptor, attenuates the cardiovascular and metabolic complications of obesity (<a href="http://www.ncbi.nlm.nih.gov/pubmed/18761356" target="_blank">10</a>). TLR4 has been involved in other metabolic complications which are less understood, like the progression of simple steatosis to non-alcoholic steatohepatitis (NASH) associated with obesity (<a href="http://www.ncbi.nlm.nih.gov/pubmed/22253482" target="_blank">11</a>). </span><br />
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<span style="font-family: 'Trebuchet MS', sans-serif;">From the above evidence, researchers thought they had found the link between dietary fat and inflammation. Nevertheless, Erridge and Samani (<a href="http://www.ncbi.nlm.nih.gov/pubmed/19661481" target="_blank">12</a>) found that the <i>in vitro</i> evidence showing a direct activation of TLRs (they tested TLR2, TLR4 and TLR5) was caused by contamination of fatty-acid-free BSA (used to present SFAs to cells) with LPS and lipopeptide (although some authors show that BSA alone is not sufficient to activate TLR4, see below). Others have suggested that SFAs activate TLR4 signaling indirectly, promoting TLR4 dimerization and association of TLR4 with MD-2 and downstream adaptor proteins (TRIF and MyD88) into lipid rafts (<a href="http://www.ncbi.nlm.nih.gov/pubmed/19648648" target="_blank">13</a>). This latter explanation seems to be more plausible.</span><br />
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<span style="font-family: 'Trebuchet MS', sans-serif;">If SFAs promote inflammation and seem to act in part through TLR4 in <i>in vivo</i> studies, then maybe they are acting as carriers of another molecules which bind and activate TLR4. This seems to be the case. As Peter <a href="http://high-fat-nutrition.blogspot.com/2009/02/fats-absorbing-endotoxin.html" target="_blank">has blogged</a> briefly before, Ghoshal et al. (<a href="http://www.ncbi.nlm.nih.gov/pubmed/18815435" target="_blank">14</a>) demonstrated that chylomicron formation in the gut promotes LPS absorption. However, this effect is not exclusive to SFA, but to long chain fatty acids (LCFA) as they need chylomicrons for absorption/transport, in contrast to short- and medium-chain fatty acids. </span><br />
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<span style="font-family: 'Trebuchet MS', sans-serif;">Does this makes LCFAs inherently unhealthy? No. Appropriate TLR stimulation is important of adequate innate responses to pathogens and for maturation and development during childhood. Excessive uptake of LPS, promoted either by calorie excess and/or overgrowth of gram-negative gut bacteria, seem to contribute to chronic endotoxemia and disease. Endotoxin overload is particularly problematic in adults with inflammation and/or immune related diseases. </span><br />
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<span style="font-family: 'Trebuchet MS', sans-serif;"><u>Association between postprandial lipemia and inflammation</u></span><br />
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<span style="font-family: 'Trebuchet MS', sans-serif;">Fisher-Wellman & Bloomer found that isocalorically, high-fat meals promote a stronger postprandial oxidative stress than carbohydrate and/or protein meals in healthy subjects (<a href="http://www.ncbi.nlm.nih.gov/pubmed/21041812" target="_blank">13</a>). However, they used heavy whipping cream as the fat source, dextrose powder as carbohydrate and casein-whey protein powder as the protein source. This helps isolating variables (macronutrients) but doesn't help much for assessing the effect of a mixed meal composed of real food. Moreover, they didn't control for calories, as the "lipid meal" contained more calories than any other meal:</span><br />
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<tr><td style="text-align: center;"><a href="http://3.bp.blogspot.com/-hOcjn48eDWQ/T7_MFyTbjTI/AAAAAAAAAHc/6IZLYoqE4Gk/s1600/mixedmeal.bmp" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="125" src="http://3.bp.blogspot.com/-hOcjn48eDWQ/T7_MFyTbjTI/AAAAAAAAAHc/6IZLYoqE4Gk/s400/mixedmeal.bmp" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Fisher-Wellman & Bloomer, 2010</td></tr>
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<span style="font-family: 'Trebuchet MS', sans-serif;">In fact, the "protein meal" included more fat than the "lipid meal" (98g/38% vs. 93g/34%). The carbohydrate percentage was the same between the carbohydrate and the lipid meal, but the absolute amount was higher in the latter because of the calorie content. If dietary fat were </span><span style="font-family: 'Trebuchet MS', sans-serif;">indeed</span><span style="font-family: 'Trebuchet MS', sans-serif;"> to blame, it can be expected that the higher the fat content, the higher the measures of oxidative stress. But the meal with higher fat content was the mixed meal, which didn't produce significantly different results than the carbohydrate or the protein meal. </span><br />
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<span style="font-family: 'Trebuchet MS', sans-serif;">Another measure of inflammatory changes induced by specific macronutrients or meals is </span><span style="font-family: 'Trebuchet MS', sans-serif;">the activation of transcription factors and proteins involved in cellular inflammatory pathways, such as NFkB. For example, glucose ingestion (75g in 300ml water) stimulated nuclear transport of NFkB, reduced IKB-alpha protein levels and increased the activity and expression of IKK-alpha and IKK-beta in mononuclear cells (<a href="http://www.ncbi.nlm.nih.gov/pubmed/16919536" target="_blank">15</a>). This was paralleled by an increased expression of TNF-alpha and activation of NADPH oxidase. Similar results have been found after a 900kcal mixed meal (81g carbohydrate, 51g fat and 32g protein) (<a href="http://www.ncbi.nlm.nih.gov/pubmed/15051615" target="_blank">16</a>). This is to be expected as energy intake will increase mitochondrial respiration, stimulating mitochondrial ROS production. Some ROS are capable of activating NFkB, so any increase in intracellular ROS can increase NFkB-mediated signaling (<a href="http://www.ncbi.nlm.nih.gov/pubmed/8635688" target="_blank">17</a>). </span><br />
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<span style="font-family: 'Trebuchet MS', sans-serif;">Ingestion of 300kcal of cream or glucose stimulated NFkB binding, expression of SOCS3, TNF-alpha and IL-1beta in mononuclear cells of healthy subjects, but only cream increased plasma LPS and TLR4 expression (<a href="http://www.ncbi.nlm.nih.gov/pubmed/20067961" target="_blank">18</a>). This was not seen with ingestion of orange juice, probably due to the increase in uric acid associated with fructose ingestion. These results are in accordance with chylomicron-mediated transport of LPS through the gut. As expected, high FFA plus high glucose amplify the inflammatory response (<a href="http://www.ncbi.nlm.nih.gov/pubmed/20959532" target="_blank">19</a>).</span><br />
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<span style="font-family: 'Trebuchet MS', sans-serif;"><u>Hypertriglyceridemia increases endotoxemia</u></span><br />
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<span style="font-family: 'Trebuchet MS', sans-serif;">The human body must be able to cope with acute increases in LPS in plasma, attenuating the inflammatory response induced by fat ingestion. Clemente-Postigo, et al. (<a href="http://www.ncbi.nlm.nih.gov/pubmed/22394503" target="_blank">20</a>) showed that in morbidly obese subjects, endotoxin increases were strongly correlated to the difference between baseline </span><span style="font-family: 'Trebuchet MS', sans-serif;">and postprandial</span><span style="font-family: 'Trebuchet MS', sans-serif;"> triglyceride levels. They also found that baseline triglyceride level was the best variable that predicted basal LPS level in serum. In this regard, very low carbohydrate diets have shown to reduce baseline triglyceride levels and postprandial lipemia (<a href="http://www.ncbi.nlm.nih.gov/pubmed/12949361" target="_blank">21</a>, <a href="http://www.ncbi.nlm.nih.gov/pubmed/15051841" target="_blank">22</a>). In the metabolically healthy, the immune system is capable of attenuating postprandial endotoxemia (as with inflammation induced by any meal). The inflammatory nature of absorption, digestion and metabolism of macronutrients must be coupled with an anti-inflammatory period, such as fasting (depending on the inflammatory load of the diet, an overnight fast might work). By this way, the body's inflammatory balance is maintained in a healthy range. </span><br />
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<span style="font-family: 'Trebuchet MS', sans-serif;"><u>Effects of dietary PUFAs on immune cells</u></span><br />
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<span style="font-family: 'Trebuchet MS', sans-serif;">It is important to note that, although LCFA (which means they stimulate chylomicron formation and thus, LPS transport), MUFAs and PUFAs exhibit different effects than long chain SFAs. This could be related to their effects on membrane fatty acid composition. Cellular membranes are highly structured, and subtle variations in the unsaturation of phospholipids can have diverse but important molecular consequences. It is well known by now that dietary fatty acids alter the composition of membrane lipids, as they are incorporated. In immune cells, this is extremely important for the overall response to a certain stimulus, from phagocytosis against a pathogen to secretion of cytokines for proliferation and clonal expansion. Fatty acids incorporated to immune cell membranes act through different mechanisms:</span><br />
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<li><span style="font-family: 'Trebuchet MS', sans-serif;">Altering the composition of <a href="http://en.wikipedia.org/wiki/Lipid_raft" target="_blank">lipid rafts</a>. This, in turn, influences protein-protein interactions, as well as coupling ligand-receptor interaction with scaffold and intracellular signaling proteins.</span></li>
<li><span style="font-family: 'Trebuchet MS', sans-serif;">Producing intermediate molecules, such as prostaglandins. The final effect is difficult to assess, but there seem to be clear differences between the action of metabolites produced from omega 6 (O6) vs. omega 3 (O3).</span></li>
<li><span style="font-family: 'Trebuchet MS', sans-serif;">Altering membrane permeability. A higher unsaturation index (that is, the degree of unsaturation of phospholipid chains) renders a more fluid membrane, being the opposite true for a low unsaturation index. Increasing the proportion of SFA in cell membranes decreases permeability because unsaturated fatty acids chains form a "<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgRk4uVEx9B8l2ZLNoloaXKRYlb4XibN-4uNeIlofn5xqj9i-xa5lBPQW-PhHTDUam20Fn99FfPLR6yVqaUT4z1g9Gxwtq1JeJCZgSHyw6jo5q3sonjRQK55fBhBqIQiaIuBtSzzaWLOL4/s1600/Phospholipid_TvanBrussel.jpg" target="_blank">kink</a>", increasing the degrees of freedom of the molecules and its physicochemical characteristics (both individually and as a group). </span></li>
<li><span style="font-family: 'Trebuchet MS', sans-serif;">Providing <a href="http://www.lucastafur.com/2012/02/adipose-tissue-immunity-basics-1.html" target="_blank">energy</a>.</span></li>
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<span style="font-family: 'Trebuchet MS', sans-serif;">Animal and some human studies have shown that altering the amount of either O6 or O3 can affect the function of immune cells (<a href="http://www.ncbi.nlm.nih.gov/pubmed/18951005" target="_blank">23</a>; references therein):</span></div>
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<li><span style="font-family: 'Trebuchet MS', sans-serif;">Increased dietary intake of EPA (2.7g/day) has shown to reduce PGE2 production (a metabolite of arachidonic acid) in human mononuclear cells (MNCs). </span></li>
<li><span style="font-family: 'Trebuchet MS', sans-serif;">Fish oil ingestion has shown to increase the production of 5-series leukotrienes, products derived from EPA.</span></li>
<li><span style="font-family: 'Trebuchet MS', sans-serif;">EPA/DHA or fish oil also induces the production of <a href="http://en.wikipedia.org/wiki/Resolvin" target="_blank">resolvins</a>, which have anti-inflammatory properties.</span></li>
<li><span style="font-family: 'Trebuchet MS', sans-serif;">Increasing membrane permeability by increasing the unsaturation index might increase phagocytosis by MNCs. The phagocytic index of neutrophils and monocytes has shown to be negatively correlated with palmitic acid content, but positively correlated with the content of PUFAs, specifically O3. In healthy humans, 1.5g/day of EPA+DHA for 6 months increased the phagocytic activity in monocytes and neutrophils by 200% and 40%, respectively. </span></li>
<li><span style="font-family: 'Trebuchet MS', sans-serif;">Arachidonic acid, EPA and DHA have shown to inhbit T-cell proliferation and IL-2 production <i>in vitro</i>. This has been replicated in animal models with fish oil and/or EPA/DHA in high doses. O3 might also affect the composition (and hence function) of lipid rafts, as treatment of T-cells with O3 displaces acylated proteins anchored to the inner lipid leaflet from lipid rafts, but not GPI-anchored proteins. This displacement (probably as a direct consequence of incorporation of EPA and DHA into membranes) affects the intracellular signaling pathway associated with the protein being displaced, such as <a href="http://en.wikipedia.org/wiki/Linker_of_activated_T_cells" target="_blank">LAT</a>. </span></li>
<li><span style="font-family: 'Trebuchet MS', sans-serif;">Increasing the amount of dietary fish oil in rats causes a reduction in MHC II expression on dendritic cells, as well as levels of CD2, CD11a and CD18. Arachidonic acid and DHA, by slowing the transit of new MHC I molecules from the endoplasmic reticulum to Golgi, have shown to decrease surface MHC I expression, decreasing cytotoxic T-cell mediated lysis of target cells enriched in these fatty acids. </span></li>
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<span style="font-family: 'Trebuchet MS', sans-serif;">The acute effect of increasing doses of animal O3 is a reduction in arachidonic acid-derived inflammatory metabolites, increases in membrane permeability and anti-inflammatory molecules derived from EPA/DHA, as well as reduction in T-cell activation and antigenic stimulation. O3 also have direct effects: inhibition of LPS or lipopeptide-stimulated COX2 expression and LPS-induced NFkB activation (</span><a href="http://www.ncbi.nlm.nih.gov/pubmed/12562875" style="font-family: 'Trebuchet MS', sans-serif;" target="_blank">24</a><span style="font-family: 'Trebuchet MS', sans-serif;">,</span> <span style="font-family: 'Trebuchet MS', sans-serif;"><a href="http://www.ncbi.nlm.nih.gov/pubmed/14966134" target="_blank">25</a>). Interestingly, there is evidence that the anti-inflammatory effects seen for O3 are dependent on their oxidation. Oxidized EPA, but not unoxidized EPA, inhibits NFkB activation and expression of inflammatory molecules in a PPARa dependent manner, as well as chemotaxis </span><span style="font-family: 'Trebuchet MS', sans-serif;">(</span><a href="http://www.ncbi.nlm.nih.gov/pubmed/15231516" style="font-family: 'Trebuchet MS', sans-serif;" target="_blank">26</a><span style="font-family: 'Trebuchet MS', sans-serif;">,</span> <span style="font-family: 'Trebuchet MS', sans-serif;"><a href="http://www.ncbi.nlm.nih.gov/pubmed/15331934" target="_blank">27</a>, <a href="http://www.ncbi.nlm.nih.gov/pubmed/12149216" target="_blank">28</a>). Oxidized, but not unoxidized DHA, inhibits polychlorinated biphenyl-induced NFkB activation and MCP-1 expression, effects probably mediated by its oxidation products (A4/J4 neuroprostanes) (<a href="http://www.ncbi.nlm.nih.gov/pubmed/21130106" target="_blank">29</a>). Thus, it seems that contrary to what is believed, oxidation of O3 PUFA is necessary to mediate their beneficial biological effects. </span></div>
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<span style="font-family: 'Trebuchet MS', sans-serif;">The effects of MUFAs (mainly oleate) have not been studied in detail as with PUFAs. In contrast to palmitate and stearate, oleate do not seems to induce TLR2/4 activation in monocytes </span><span style="font-family: 'Trebuchet MS', sans-serif;">(</span><a href="http://www.ncbi.nlm.nih.gov/pubmed/20959532" style="font-family: 'Trebuchet MS', sans-serif;" target="_blank">19</a><span style="font-family: 'Trebuchet MS', sans-serif;">) (in this case, the authors used a BSA-only control, showing no activation of TLR). This makes sense, as oleate is the main FFA in human circulation (<a href="http://www.ncbi.nlm.nih.gov/pubmed/4639017?dopt=Abstract" target="_blank">30</a>). However, oleate has a strong inflammatory effect on human islet cells, increasing the levels of IL-1beta mRNA, IL-6 mRNA and IL-8 mRNA compared to palmitate and stearate, effect which was amplified by high glucose levels (<a href="http://www.ncbi.nlm.nih.gov/pubmed/19819943" target="_blank">31</a>). In contrast with the latter two, the expression of IL-1Ra (antagonist of IL-1) was lower with oleate. The authors suggested that oleate-mediated islet inflammation could be hormetic (which makes complete sense).</span><br />
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<div style="text-align: justify;">
<span style="font-family: 'Trebuchet MS', sans-serif;">Oleate levels in circulation are determined by oral intake as well as <i>de novo</i> synthesis from SFA. This process is mediated by stearoyl-CoA desaturases (SCD), specially SCD-1 in humans (<a href="http://www.ncbi.nlm.nih.gov/pubmed/19066317" target="_blank">32</a>). This enzyme catalizes the introduction of a single double bond at the delta9, 10 position of long chain acyl-CoAs, preferentially to stearoyl-CoA and palmitoyl-CoA. Over-stimulation of SCD-1 increases the synthesis of MUFAs (like palmitoleoyl-CoA and oleoyl-CoA), affecting intermediary metabolism and promoting obesity, pathological insulin resistance, hypertriglyceridemia and hepatic steatosis (<a href="http://www.ncbi.nlm.nih.gov/pubmed/19834103" target="_blank">33</a>). SCD-1 expression is induced by SREBP-1, LXR, and inhibited by PPARbeta/delta and PPARgamma. Accordingly, SCD-1 expression and activity is increased with high carbohydrate diets (<a href="http://www.ncbi.nlm.nih.gov/pubmed/18400702" target="_blank">34</a>, <a href="http://www.ncbi.nlm.nih.gov/pubmed/18054317" target="_blank">35</a>), because insulin activates SREBP-1 and glucose (actually glucose-6-phosphate and/or xylulose-5-phosphate) activates <a href="http://www.lucastafur.com/2011/08/chrebp-forgotten-factor_16.html" target="_blank">ChREBP</a>, which increases SCD-1 expression (<a href="http://www.ncbi.nlm.nih.gov/pubmed/15118080" target="_blank">36</a>). However, it is important to interpret this data with caution, as lipogenic/lipolytic enzymes in rodents are more active than humans. Nevertheless, a high carbohydrate diet can contribute to the pool of MUFA, thereby influencing the secretion and expression of pro-inflammatory cytokines.</span><br />
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<span style="font-family: 'Trebuchet MS', sans-serif;">In contrast, EPA has shown to decrease the level of SCD-1 mRNA and SREBP-1c mRNA in Hep G2 cells (<a href="http://www.ncbi.nlm.nih.gov/pubmed/21291825" target="_blank">37</a>) and omega 3 status is important for controlling the activity and expression of SCD-1 in rats (<a href="http://www.ncbi.nlm.nih.gov/pubmed/22047910" target="_blank">38</a>). </span></div>
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<span style="font-family: 'Trebuchet MS', sans-serif;"><u>Albumin binds fatty acids and LPS</u></span><br />
<span style="font-family: 'Trebuchet MS', sans-serif;"><br /></span></div>
<div style="text-align: justify;">
<span style="font-family: 'Trebuchet MS', sans-serif;"><i>In vitro</i>, one of the most inflammatory fatty acids is lauric acid, which activates NFkB, partially mediated by the TLR4-MyD88/PI3K/Akt pathway, while DHA inhibits this effect (<a href="http://www.ncbi.nlm.nih.gov/pubmed/12865424" target="_blank">39</a>). SFAs released by adipocytes (mainly palmitate) are also able to activate TLR4 in macrophages, activating NFkB by a mechanism shared partially with LPS (<a href="http://www.ncbi.nlm.nih.gov/pubmed/17082484" target="_blank">40</a>). It seems that activation of inflammatory genes in different immune cells is related to chain length (<a href="http://www.ncbi.nlm.nih.gov/pubmed/18599066" target="_blank">41</a>). This suggests that in addition to promoting dimerization and organization of TLR4 with adaptor and co-stimulatory molecules into lipid rafts, some SFA could indeed activate TLR4 independently. What is really interesting is that free fatty acids travel in the bloodstream bound to albumin (and the levels of individual fatty acids correlate with those found free in plasma) (<a href="http://www.jlr.org/content/2/3/268.short" target="_blank">42</a>), and recently, analysis by surface plasmon resonance found that albumin not only binds to LPS, but also modulates its interaction with TLR4 and MD-2, and thus, controls the inflammatory response to a given endotoxin load (results not published)*. So we have a situation in which increasing the dose of O3 PUFA might increase the relative proportion of O3 bound to albumin, thus inhibiting the interaction of palmitic or stearic acid with LPS, or at least, ameliorating it. On the other hand, we can decrase the proportion of saturated fatty acids in circulation and bound to albumin by dietary means (<a href="http://www.ncbi.nlm.nih.gov/pubmed/18046594" target="_blank">43</a>, <a href="http://www.ncbi.nlm.nih.gov/pubmed/20820932" target="_blank">44</a>). Ultimately, the balance between lipolysis and oxidation determines the level of free fatty acids in circulation. A high lipolytic environment uncoupled to mitochondrial oxidation contributes to lipotoxicity and inflammation. This also holds true for LPS-induced inflammation. The perfect balance between hydrolysis of stored fatty acids and oxidation is achieved under fasting conditions. </span><br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://1.bp.blogspot.com/-qxAEU6xyrzA/T_4yPdMGulI/AAAAAAAAAJE/XKAzDjc5VVg/s1600/TLR4.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="380" src="http://1.bp.blogspot.com/-qxAEU6xyrzA/T_4yPdMGulI/AAAAAAAAAJE/XKAzDjc5VVg/s400/TLR4.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><b>TLR4 is modulated by specific fatty acids.</b> Saturated fatty acids (SFAs) activate TLR4 either by direct interaction or by promoting its dimerization and association with MD-2 into lipid rafts. Conversely, omega 3 polyunsaturated fatty acids (PUFAs) inhibit this effect, and reduces SFA-induced TLR4 activation. Both O3 PUFAs as well as O6 PUFAs are able to modulate the immune response by affecting membrane phospholipid composition. Increased levels of arachidonic acid (ARA) derived from O6 metabolism, as well as its metabolites are mainly pro-inflammatory, while those derived from O3 PUFAs are anti-inflammatory. Increasing the proportion of unsaturated fatty acids also changes membrane fluidity, affecting immune functions such as phagocytosis. Activation of TLR4 promotes the association of adaptor molecules such as TIRAP, MyD88 and IRAK. IRAK activates TRAF6, which interacts with TAK1, leading to the phosphorylation (denoted by the yellow P) of IKK/NEMO and its activation. This complex is able to phosphorylate IkB, thus letting transcriptionally active NFkB migrate into the nucleus. Once activated, NFkB increases the expression of pro-inflammatory genes, such as TNFa, IL-1 and IL-6. See text for details.</td></tr>
</tbody></table>
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<span style="font-family: 'Trebuchet MS', sans-serif;"><u>Summary</u></span><br />
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<span style="background-color: white; font-family: 'Trebuchet MS', sans-serif;">The composition of different fatty acids in the diet modulate endotoxemia. From the available evidence, there is consistent research which shows that:</span></div>
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<ul>
<li><span style="background-color: white; font-family: 'Trebuchet MS', sans-serif;">Saturated fatty acids (SFAs) activate TLR4 and the downstream signaling pathway, ultimately leading to the activation of NFkB, which increases the expression of pro-inflammatory molecules (TNFa, IL-6, etc.).</span></li>
<li><span style="font-family: 'Trebuchet MS', sans-serif;">SFAs might contribute directly (by interacting with LPS and/or TLR4-MD-2) or indirectly (by reorganizing lipid rafts). In either case, an increase in the level of SFA promotes the activation of this pathway. </span></li>
<li><span style="font-family: 'Trebuchet MS', sans-serif;">The activation of TLR4 has been shown to be important for the onset and development of metabolic diseases such as obesity, diabetes and non-alcoholic hepatic steatosis.</span></li>
<li><span style="font-family: 'Trebuchet MS', sans-serif;">LPS uptake is mediated through chylomicrons and is promoted by a loss of barrier function of the small intestine.</span></li>
<li><span style="font-family: 'Trebuchet MS', sans-serif;">The level of endotoxemia correlates with baseline and post-prandial triglyceride levels.</span></li>
<li><span style="font-family: 'Trebuchet MS', sans-serif;">O3 PUFAs (EPA and DHA) have shown an inhibitory effect on LPS and LPS plus SFA-induced TLR4 activation. </span></li>
<li><span style="font-family: 'Trebuchet MS', sans-serif;">The oxidation of O3 PUFAs seems to be necessary for their anti-inflammatory effects.</span></li>
<li><span style="font-family: 'Trebuchet MS', sans-serif;">The level of SFA in the bloodstream is controlled by diet as well as the cellular energy status. </span></li>
<li><span style="font-family: 'Trebuchet MS', sans-serif;">MUFAs, in most studies, seem to be neutral. However, there is some evidence linking excess oleate and SCD-1 activity to cellular dysfunction, particularly beta-cell abnormalities. EPA has opposite effects and reduces SCD-1 expression.</span></li>
<li><span style="font-family: 'Trebuchet MS', sans-serif;">Albumin binds both fatty acids and LPS, and modulates the inflammatory response to a given LPS load. The relative proportion of individual fatty acids bound to albumin might influence the binding of LPS to TLR4, thus affecting the activation of the downstream signaling pathway. </span></li>
</ul>
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<span style="font-family: 'Trebuchet MS', sans-serif;"><u>Practical recommendations</u></span><br />
<span style="font-family: 'Trebuchet MS', sans-serif;"><br /></span></div>
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<span style="font-family: 'Trebuchet MS', sans-serif;">For people with autoimmune and/or inflammatory problems, I recommend the following measures to be taken with respect to fatty acids in the diet:</span><br />
<ol>
<li><span style="font-family: 'Trebuchet MS', sans-serif;">Reduce and control the amount of O6 PUFA, specially from vegetable sources (linoleic acid).</span></li>
<li><span style="font-family: 'Trebuchet MS', sans-serif;">Control the amount of SFAs. Consumption of dairy fat seems to be protective against endotoxemia (<a href="http://www.ncbi.nlm.nih.gov/pubmed/21524510" target="_blank">45</a>). Ghee might be a better option than butter. Better to avoid protein-rich dairy.</span></li>
<li><span style="font-family: 'Trebuchet MS', sans-serif;">Increase the amount of marine EPA and DHA (O3 PUFAs). This should work best increasing the consumption of marine foods, but might be a problem for those with leaky gut given the presence of some metals in seafood. Individual tolerance must be assessed. If very sensitive, start with dietary supplements. A high dose (3-5g/day of EPA + DHA) might work first, and the those should be lowered afterwards (<a href="http://www.ncbi.nlm.nih.gov/pubmed/21159789/" target="_blank">46</a>). The higher the baseline triglyceride levels, the higher the dose. Additionally, the worse the inflammatory/immune status, the higher and longer the supplementation. This can be assessed using traditional blood markers (C-reactive protein, etc.) and symptoms. It has been shown that the effects of O3 supplementation are influenced by the O3 status of the subject (<a href="http://www.ncbi.nlm.nih.gov/pubmed/22628615?dopt=Abstract" target="_blank">47</a>). High inflammatory markers and/or symptoms might reflect O3 status.</span></li>
<li><span style="font-family: 'Trebuchet MS', sans-serif;">Avoid industrial trans-fatty acids.</span></li>
</ol>
<br />
<span style="font-family: 'Trebuchet MS', sans-serif;">* Work was presented in the <a href="http://www.inmunoperu2012.org/espanol.php" target="_blank">Inmunoperu 2012</a> conference. More information when available. </span><br />
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</div>Anonymousnoreply@blogger.com32tag:blogger.com,1999:blog-4724838399830873886.post-67442838828896982202012-07-05T14:52:00.001-07:002017-03-13T06:07:40.220-07:00News and some links<br />
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Unfortunately, I will not be able
to attend to <a href="http://ancestralhealthsymposium2012.weebly.com/index.html" target="_blank">AHS</a> this year, due to some unexpected financial and academic (damn
single molecules!) problems. I was looking forward to meet most of the
“paleosphere” and discuss about science with very bright people. I hope I can make
it in 2013. </div>
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<br /></div>
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I have been very busy working on
the lab, teaching biochemistry and cell biology in Med School and doing a post-graduate
diploma in basic and clinical immunology. Because of this, I have had little
time for reading carefully studies which are not related to my thesis, and in
my short spare time I wanted to let my brain “rest” a little bit, although I
have read some (but not as much as I would
like to). Accordingly, I haven’t had any time to update the blog. Nonetheless,
I have an almost finished post on dietary fats and immune function, which may
raise some controversy in the “low carb” community. I want to finish and
publish this post once for all (it has been almost finished for almost one
month now). I might add some information that I was keeping for my AHS talk (see bottom of the post). </div>
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In the meantime, and to make
something productive out of this post, here are some studies I have
found interesting lately (not all related to the topic of my blog, by the way).</div>
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<b><a href="http://www.ncbi.nlm.nih.gov/pubmed/22700956" target="_blank">Myocardial Infarction Triggers Chronic Cardiac Autoimmunity in Type 1 Diabetes</a></b></div>
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Inducing myocardial infarction
(MI) in NOD mice (non-obese diabetic mice) triggers the development of severe post-infarction autoimmune syndrome characterized by lymphocyte infiltration to the myocardium, infarct expansion, and autoantibody and Th1 type response to cardiac alpha-myosin. 83% of a sample of post-myocardial infarction T1D patients showed positive tests for autoantibody against cardiac proteins. </div>
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://4.bp.blogspot.com/-rTUKYu3yKWg/T_XV_PPzxOI/AAAAAAAAAH8/j5E7gS7l_XE/s1600/nod.bmp" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="170" src="http://4.bp.blogspot.com/-rTUKYu3yKWg/T_XV_PPzxOI/AAAAAAAAAH8/j5E7gS7l_XE/s320/nod.bmp" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Post-infarcted myocardium from NOD mice showed extensive lymphocytic infiltrates resembling those from pancreas islets, and extended into the non-infarcted myocardium (left image). Normal mice (B6) showed no infiltration nor expansion, but normal infarct healing and scar formation (right image).
<span style="background-color: white; color: black;"><a href="http://www.sciencemag.org/help/about/copyright.dtl" style="border: 0px; font-family: 'Lucida Grande', arial, helvetica, sans-serif; font-size: 11px; line-height: 14px; margin: 0px; outline-style: none; padding: 0px; text-align: left; vertical-align: baseline;">© 2012 American Association for the Advancement of Science. All Rights Reserved</a><span style="font-family: 'Lucida Grande', arial, helvetica, sans-serif; font-size: 11px; line-height: 14px; text-align: left;">.</span></span></td></tr>
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<b><a href="http://www.ncbi.nlm.nih.gov/pubmed/22713870" target="_blank">Maternal western diet causes inflammatory milk and TLR2/4-dependent neonatal toxicity</a></b><br />
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<span style="background-color: white; line-height: 1.125em; text-align: left;"><span style="font-family: 'Trebuchet MS', sans-serif;">Wild-type (WT) female C57B6J mice were fed with normal chow or chow supplemented with extra cholesterol, fat and sucrose (Western diet, WD) for 2 weeks before breeding with WT male mice, and were maintained on chow or WD during pregnancy and lactation. Pups from mice fed a WD exhibited alopecia* (see figure), increased body weight, thicker lipid layer in the skin (increasing the lipid/skin weight ratio), skin leukocyte infiltration and increased expression of inflammatory genes (IL-1b, TNFa, COX-2, iNOS, MCP-1) in the skin, intestines and liver.</span></span><br />
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<tr><td style="text-align: center;"><a href="http://1.bp.blogspot.com/-E86meYMctRc/T_XUZ-xnKNI/AAAAAAAAAHs/0BOec8xQRJs/s1600/wdmilk.bmp" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="281" src="http://1.bp.blogspot.com/-E86meYMctRc/T_XUZ-xnKNI/AAAAAAAAAHs/0BOec8xQRJs/s400/wdmilk.bmp" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">WD-milk promotes alopecia.
<span style="color: black; font-size: xx-small;"><a href="http://www.cshlpress.com/" rel="external-nw" style="background-color: white; border: none; font-family: arial, sans-serif; line-height: 11px; margin: 0px; outline-style: none; padding: 0px; text-align: left; text-decoration: none; vertical-align: baseline;" target="_blank" title="[opens in a new window]">Copyright © 2012 by Cold Spring Harbor Laboratory Press</a> </span></td></tr>
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<span style="background-color: white; line-height: 1.125em; text-align: left;"><span style="font-family: 'Trebuchet MS', sans-serif;">These deleterious effects were related to the composition of the WD, which contained more saturated fatty acids (SFA) than the chow diet (48.9% vs. 17.6%) **, as well as to the composition of the milk from WD fed mice, which was 24% higher in fat than control. Milk triglycerides from WD-milk had a higher percentage of long chain fatty acids (elongation ratio (C18:0/C10:0) was increased 1.9-fold) and saturated fatty acids (saturation ratio (C18:0/C18:2) was 2.8-fold higher). </span></span><br />
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<span style="background-color: white; line-height: 1.125em; text-align: left;"><span style="font-family: 'Trebuchet MS', sans-serif;">Furthermore, the inflammatory effects induced by the increase in long-chain saturated fatty acids in maternal milk was in part mediated through the production of ceramides and glucosylceramides, as well as lactosylceramide, which was capable of inducing the expression of the aforementioned inflammatory genes in RAW264.7 cells (mouse macrophage cell line). Deletion of TLR2/4 abolished or decreased some of the toxic effects observed, suggesting that TLR-signaling is involved (deletion of adaptor molecule Myd88 also reduced toxicity). Germ-free mice showed an increased toxicity for WD milk, suggesting a protective effect of the normal gut microbiota. </span></span><br />
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<span style="background-color: white; font-family: 'Trebuchet MS', sans-serif; line-height: 18px; text-align: left;"><b><a href="http://www.ncbi.nlm.nih.gov/pubmed/22608008" target="_blank">Time-Restricted Feeding without Reducing <span style="background-color: white;">Caloric Intake Prevents Metabolic Diseases </span><span style="background-color: white;">in Mice Fed a High-Fat Diet</span></a></b></span><br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://download.cell.com/images/journalimages/1550-4131/PIIS1550413112001891.fx1.lrg.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="311" src="http://download.cell.com/images/journalimages/1550-4131/PIIS1550413112001891.fx1.lrg.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="background-color: white;"><span style="font-family: arial, helvetica, 'Lucida Grande', Tahoma, verdana, sans-serif; font-size: 10px; line-height: 12px; text-align: left;">Fasting improves metabolic alterations induced by high-fat diets in mice. Copyright © 2012 </span><a href="http://www.elsevier.com/" style="font-family: arial, helvetica, 'Lucida Grande', Tahoma, verdana, sans-serif; font-size: 10px; line-height: 12px; margin: 0px; padding: 0px; text-align: left; text-decoration: none;" target="Elsevier">Elsevier Inc.</a><span style="font-family: arial, helvetica, 'Lucida Grande', Tahoma, verdana, sans-serif; font-size: 10px; line-height: 12px; text-align: left;"> All rights reserved.</span></span>
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<span style="font-family: 'Trebuchet MS', sans-serif;"><span style="line-height: 18px;">When fed a high-fat diet, C57BL/6J mice develop inflammatory symptoms and ultimately, metabolic disease. What Du, et al. wanted to know if circadian metabolic oscillations influence the response of mice to a HFD. They used a restricted feeding regimen, which has shown to reset some circadian rhythms. They found that, although eating the same calories overall, mice eating all of the calories from the HFD during an 8-hour window do not developed the symptoms exhibited by mice eating a HFD ad libitum (see figure). In other words, eating the same unhealthy diet at the same level of calories, but restricting it to an 8-hour window, practically abolishes all the deleterious effects***. This effects were mediated by preventing the abnormalities in the circadian rhythm induced by high-fat feeding.</span></span></div>
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<span style="font-family: 'Trebuchet MS', sans-serif;"><b><a href="http://www.ncbi.nlm.nih.gov/pubmed/22674328" target="_blank">Interactions between commensal fungi and the C-type lectin receptor Dectin-1 influence colitis</a></b></span></h1>
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<div>
<span style="font-family: 'Trebuchet MS', sans-serif;">Iliev, et al. show that although bacteria are a very important (and the major component) for the gut microbiota, there are also other organisms which play an essential role in the host's health. This is the case for some fungi, which interact with the host through dectin-1 receptors, inducing a Th17-type immune response. Mice lacking dectin-1 are susceptible to DSS-induced colitis, and show an abnormal inflammatory response. Inducing colitis altered the mycobiome, and treatment with fluconazole (antifungal) ameliorated inflammation. Analysis of the mouse fungal microbiome revealed that 65.2% of the sequences identified corresponded to <i>Candida tropicalis</i>, an opportunistic pathogen. Their results showed that dectin-1 restricts its body localization to the intestinal lumen (so there is no invasion of inflamed tissues). Colitis also increased the proportion of <i>Candida</i> and <i>Trichosporon</i> (opportunistic pathogens) and reduced the levels of <i>Saccharomyces</i> (non-pathogenic). Supporting their hypothesis, they found an haplotype in the <i>CLEC7A</i> gene (human dectin-1 gene) which was correlated with severe forms of ulcerative colitis, but not with non-severe manifestations.</span></div>
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://2.bp.blogspot.com/-fDcJV14vMe4/T_Xi16Y_6wI/AAAAAAAAAII/B9UPAWVmrtk/s1600/mycobiome.bmp" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="234" src="http://2.bp.blogspot.com/-fDcJV14vMe4/T_Xi16Y_6wI/AAAAAAAAAII/B9UPAWVmrtk/s320/mycobiome.bmp" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Fungi levels are an important part of the murine gut microbiota. This probably occurs also in humans.
<span style="color: black;"><a href="http://www.sciencemag.org/help/about/copyright.dtl" style="border: 0px; font-family: 'Lucida Grande', arial, helvetica, sans-serif; font-size: 11px; line-height: 14px; margin: 0px; outline-style: none; padding: 0px; text-align: left; vertical-align: baseline;">© 2012 American Association for the Advancement of Science. All Rights Reserved</a><span style="font-family: 'Lucida Grande', arial, helvetica, sans-serif; font-size: 11px; line-height: 14px; text-align: left;">.</span></span></td></tr>
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<b><span style="font-family: 'Trebuchet MS', sans-serif;"><a href="http://www.ncbi.nlm.nih.gov/pubmed/22727695" target="_blank">A Single-Molecule Hershey-Chase Experiment</a></span></b></h1>
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<span style="font-family: 'Trebuchet MS', sans-serif;">The mechanism by which phages transfer their DNA to bacteria has been a key question for decades. Using a single-molecule system with two different strains of <a href="http://en.wikipedia.org/wiki/Lambda_phage" target="_blank">lambda phage</a> (differing in genome length), Van Valen, et al. found that the time it takes for lambda phage to transfer its DNA to a single <i>E.coli</i> cell takes 5 minutes (with high cell-to-cell variability and sometimes showing long pauses), compared to what it is seen <i>in vitro</i>, where the process takes roughly 10 seconds. The <i>in vivo </i>velocity of DNA ejection seemed to be determined by the amount of DNA ejected, not by the amount of DNA left in the viral capsid (which is what has been seen <i>in vitro</i>). The method utilized by the authors is theoretically simple (see figure). They stained viral DNA while still in the capsid with a cyanide dye (SYTOX orange), after which excessive dye is washed out. The stained phages are then briefly bound to bacterial cells, which are pipetted into a flow chamber. After washing again with buffer, the sample is imaged with time-lapse bright-field and fluorescence microscopy. The ejection of DNA is measured by comparing the fluorescence intensity inside the phage capsid to that of the bacterial cell: a loss of fluorescence inside the capsid with a concomitant increase in the cell represents DNA translocation.</span></div>
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<tr><td style="text-align: center;"><a href="http://1.bp.blogspot.com/-N2LXUyhrOy4/T_X1CUMQN4I/AAAAAAAAAIU/DEiiBtNWQOU/s1600/phage.bmp" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="254" src="http://1.bp.blogspot.com/-N2LXUyhrOy4/T_X1CUMQN4I/AAAAAAAAAIU/DEiiBtNWQOU/s320/phage.bmp" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="background-color: white;"><span style="font-family: arial, helvetica, 'Lucida Grande', Tahoma, verdana, sans-serif; font-size: 10px; line-height: 12px; text-align: left;">Copyright © 2012 </span><a href="http://www.elsevier.com/" style="font-family: arial, helvetica, 'Lucida Grande', Tahoma, verdana, sans-serif; font-size: 10px; line-height: 12px; margin: 0px; padding: 0px; text-align: left; text-decoration: none;" target="Elsevier">Elsevier Inc.</a><span style="font-family: arial, helvetica, 'Lucida Grande', Tahoma, verdana, sans-serif; font-size: 10px; line-height: 12px; text-align: left;"> All rights reserved.</span></span>
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<span style="font-family: 'Trebuchet MS', sans-serif;">This study is important for several reasons. First, it supports the notion that biological process must be seen at a single-molecule level for understanding them. When we do an experiment in bulk, we have millions of molecules at the time interacting. Any measure of a given parameter is just an average of what is being seen. But many times, we fail to see the behaviour of outliers, or in other case, we can have individual differences which are obscured by the number of molecules being analyzed in a given moment and a given space. What is more realistic is to measure single molecules and average repeated experiments. In this way, we a. reduce individual variability obscured by the average, b. observe how molecules behave inside cells (interactions are between single molecules) and c. reduce the influence of other co-solutes and molecules which might influence the process being observed. </span><br />
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<tr><td style="text-align: center;"><a href="http://2.bp.blogspot.com/-qqPtUanaSNo/T_X3MPkT1YI/AAAAAAAAAIc/K2LJZ0k6YOc/s1600/phage2.bmp" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="270" src="http://2.bp.blogspot.com/-qqPtUanaSNo/T_X3MPkT1YI/AAAAAAAAAIc/K2LJZ0k6YOc/s320/phage2.bmp" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="background-color: white;"><span style="font-family: arial, helvetica, 'Lucida Grande', Tahoma, verdana, sans-serif; font-size: 10px; line-height: 12px; text-align: left;">Fluorescence imaging of the process of DNA ejection to a single <i>E.coli</i> cell. Copyright © 2012 </span><a href="http://www.elsevier.com/" style="font-family: arial, helvetica, 'Lucida Grande', Tahoma, verdana, sans-serif; font-size: 10px; line-height: 12px; margin: 0px; padding: 0px; text-align: left; text-decoration: none;" target="Elsevier">Elsevier Inc.</a><span style="font-family: arial, helvetica, 'Lucida Grande', Tahoma, verdana, sans-serif; font-size: 10px; line-height: 12px; text-align: left;"> All rights reserved.</span></span>
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<span style="font-family: 'Trebuchet MS', sans-serif;">Second, this finding challenges what was thought about this process based on <i>in vitro</i> evidence: that the amount of DNA inside the capsid was the driving force for DNA ejection. This was the most logical hypothesis, given that before ejection, the repulsive forces experienced by the tight packing of the DNA would promote its ejection. Lastly, the method utilized its a novel approach that can be expanded to other systems. </span><br />
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<span style="background-color: white; line-height: 1.125em; text-align: left;"><span style="font-family: 'Trebuchet MS', sans-serif;">* Hair was recovered after weaning.</span><br />
<span style="background-color: white; font-family: 'Trebuchet MS', sans-serif; line-height: 18px; text-align: left;">** It was also lower in PUFA (12.2% in WD vs. 61.8% in chow), but much higher in sucrose (152.8g/kg in WD vs. 0g/kg in chow). </span><br />
<span style="background-color: white; font-family: 'Trebuchet MS', sans-serif; line-height: 18px; text-align: left;">*** Nevertheless, some inflammatory cytokines were still increased compared to control.</span><br />
<span style="background-color: white; font-family: 'Trebuchet MS', sans-serif; line-height: 18px; text-align: left;"><br /></span><br />
<span style="background-color: white; font-family: 'Trebuchet MS', sans-serif; line-height: 18px; text-align: left;">PD. I wanted to make public my thanks to the AHS organizers for their help with paper work and answering any question I had immediately. I feel very bad for cancelling my talk, specially after their help. Also, I want to thank to everyone who supported my talk me via donations. Please, if anyone who donated wants a refund, send me an <a href="mailto:lucas@lucastafur.com" target="_blank">email</a>. For anyone who was expecting my talk, I will compensate it with more information on my blog. First, I will finish and post my second post on my nutrition immunotherapy protocol, and second, I will add a new page to the blog with schematic and didactic diagrams made for my presentation. They will be available for free to everyone. </span></span><br />
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<span style="float: left; padding: 5px;"><a href="http://www.researchblogging.org/"><img alt="ResearchBlogging.org" src="http://www.researchblogging.org/public/citation_icons/rb2_large_gray.png" style="border: 0;" /></a></span><span class="Z3988" title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.jtitle=Science+%28New+York%2C+N.Y.%29&rft_id=info%3Apmid%2F22674328&rfr_id=info%3Asid%2Fresearchblogging.org&rft.atitle=Interactions+between+commensal+fungi+and+the+C-type+lectin+receptor+Dectin-1+influence+colitis.&rft.issn=0036-8075&rft.date=2012&rft.volume=336&rft.issue=6086&rft.spage=1314&rft.epage=7&rft.artnum=&rft.au=Iliev+ID&rft.au=Funari+VA&rft.au=Taylor+KD&rft.au=Nguyen+Q&rft.au=Reyes+CN&rft.au=Strom+SP&rft.au=Brown+J&rft.au=Becker+CA&rft.au=Fleshner+PR&rft.au=Dubinsky+M&rft.au=Rotter+JI&rft.au=Wang+HL&rft.au=McGovern+DP&rft.au=Brown+GD&rft.au=Underhill+DM&rfe_dat=bpr3.included=1;bpr3.tags=Biology%2CNutrition%2C+Immunology%2C+Molecular+Biology%2C+Microbiology">Iliev ID, Funari VA, Taylor KD, Nguyen Q, Reyes CN, Strom SP, Brown J, Becker CA, Fleshner PR, Dubinsky M, Rotter JI, Wang HL, McGovern DP, Brown GD, & Underhill DM (2012). Interactions between commensal fungi and the C-type lectin receptor Dectin-1 influence colitis. <span style="font-style: italic;">Science (New York, N.Y.), 336</span> (6086), 1314-7 PMID: <a href="http://www.ncbi.nlm.nih.gov/pubmed/22674328" rev="review">22674328</a></span>
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<span class="Z3988" title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.jtitle=Current+biology+%3A+CB&rft_id=info%3Apmid%2F22727695&rfr_id=info%3Asid%2Fresearchblogging.org&rft.atitle=A+Single-Molecule+Hershey-Chase+Experiment.&rft.issn=0960-9822&rft.date=2012&rft.volume=&rft.issue=&rft.spage=&rft.epage=&rft.artnum=&rft.au=Van+Valen+D&rft.au=Wu+D&rft.au=Chen+YJ&rft.au=Tuson+H&rft.au=Wiggins+P&rft.au=Phillips+R&rfe_dat=bpr3.included=1;bpr3.tags=Biology%2CPhysics%2CHealth%2CBiology%2C+Biophysics%2C+%2C+Molecular+Physics%2C+Microbiology">Van Valen D, Wu D, Chen YJ, Tuson H, Wiggins P, & Phillips R (2012). A Single-Molecule Hershey-Chase Experiment. <span style="font-style: italic;">Current biology : CB</span> PMID: <a href="http://www.ncbi.nlm.nih.gov/pubmed/22727695" rev="review">22727695</a></span>
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<span class="Z3988" title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.jtitle=Cell+metabolism&rft_id=info%3Apmid%2F22608008&rfr_id=info%3Asid%2Fresearchblogging.org&rft.atitle=Time-Restricted+Feeding+without+Reducing+Caloric+Intake+Prevents+Metabolic+Diseases+in+Mice+Fed+a+High-Fat+Diet.&rft.issn=1550-4131&rft.date=2012&rft.volume=15&rft.issue=6&rft.spage=848&rft.epage=60&rft.artnum=&rft.au=Hatori+M&rft.au=Vollmers+C&rft.au=Zarrinpar+A&rft.au=Ditacchio+L&rft.au=Bushong+EA&rft.au=Gill+S&rft.au=Leblanc+M&rft.au=Chaix+A&rft.au=Joens+M&rft.au=Fitzpatrick+JA&rft.au=Ellisman+MH&rft.au=Panda+S&rfe_dat=bpr3.included=1;bpr3.tags=Biology%2CHealth%2CNutrition%2C+Immunology%2C+Molecular+Biology">Hatori M, Vollmers C, Zarrinpar A, Ditacchio L, Bushong EA, Gill S, Leblanc M, Chaix A, Joens M, Fitzpatrick JA, Ellisman MH, & Panda S (2012). Time-Restricted Feeding without Reducing Caloric Intake Prevents Metabolic Diseases in Mice Fed a High-Fat Diet. <span style="font-style: italic;">Cell metabolism, 15</span> (6), 848-60 PMID: <a href="http://www.ncbi.nlm.nih.gov/pubmed/22608008" rev="review">22608008</a></span>
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<span class="Z3988" title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.jtitle=Genes+%26+development&rft_id=info%3Apmid%2F22713870&rfr_id=info%3Asid%2Fresearchblogging.org&rft.atitle=Maternal+western+diet+causes+inflammatory+milk+and+TLR2%2F4-dependent+neonatal+toxicity.&rft.issn=0890-9369&rft.date=2012&rft.volume=26&rft.issue=12&rft.spage=1306&rft.epage=11&rft.artnum=&rft.au=Du+Y&rft.au=Yang+M&rft.au=Lee+S&rft.au=Behrendt+CL&rft.au=Hooper+LV&rft.au=Saghatelian+A&rft.au=Wan+Y&rfe_dat=bpr3.included=1;bpr3.tags=Biology%2CNutrition%2C+Immunology%2C+Molecular+Biology">Du Y, Yang M, Lee S, Behrendt CL, Hooper LV, Saghatelian A, & Wan Y (2012). Maternal western diet causes inflammatory milk and TLR2/4-dependent neonatal toxicity. <span style="font-style: italic;">Genes & development, 26</span> (12), 1306-11 PMID: <a href="http://www.ncbi.nlm.nih.gov/pubmed/22713870" rev="review">22713870</a></span>
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<span class="Z3988" title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.jtitle=Science+translational+medicine&rft_id=info%3Apmid%2F22700956&rfr_id=info%3Asid%2Fresearchblogging.org&rft.atitle=Myocardial+infarction+triggers+chronic+cardiac+autoimmunity+in+type+1+diabetes.&rft.issn=1946-6234&rft.date=2012&rft.volume=4&rft.issue=138&rft.spage=&rft.epage=&rft.artnum=&rft.au=Gottumukkala+RV&rft.au=Lv+H&rft.au=Cornivelli+L&rft.au=Wagers+AJ&rft.au=Kwong+RY&rft.au=Bronson+R&rft.au=Stewart+GC&rft.au=Schulze+PC&rft.au=Chutkow+W&rft.au=Wolpert+HA&rft.au=Lee+RT&rft.au=Lipes+MA&rfe_dat=bpr3.included=1;bpr3.tags=Biology%2CNutrition%2C+Immunology%2C+Molecular+Biology">Gottumukkala RV, Lv H, Cornivelli L, Wagers AJ, Kwong RY, Bronson R, Stewart GC, Schulze PC, Chutkow W, Wolpert HA, Lee RT, & Lipes MA (2012). Myocardial infarction triggers chronic cardiac autoimmunity in type 1 diabetes. <span style="font-style: italic;">Science translational medicine, 4</span> (138) PMID: <a href="http://www.ncbi.nlm.nih.gov/pubmed/22700956" rev="review">22700956</a></span>Anonymousnoreply@blogger.com4tag:blogger.com,1999:blog-4724838399830873886.post-51311889459764394352012-03-14T13:52:00.001-07:002017-03-13T06:07:40.206-07:00Nutritional immunotherapy: An overview<div style="text-align: justify;">
<span style="font-family: 'Trebuchet MS', sans-serif;">In previous posts (<a href="http://www.lucastafur.com/2012/02/adipose-tissue-immunity-basics-1.html">1</a>,<a href="http://www.lucastafur.com/2012/02/adipose-tissue-immunity-basics-2.html">2</a>), I have </span><span style="font-family: 'Trebuchet MS', sans-serif;">briefly</span><span style="font-family: 'Trebuchet MS', sans-serif;"> </span><span style="font-family: 'Trebuchet MS', sans-serif;">reviewed the importance of adipocytes and molecules secreted by the adipose tissue in immunity. Overall, increases in adiposity alterate the inflammatory balance, shifting towards a pro-inflammatory state, which contributes to the development of obesity-associated diseases. </span></div>
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<span style="font-family: 'Trebuchet MS', sans-serif;">Given that metabolic and immune pathways are interconnected, and that metabolism controls function in immune cells, it is possible to modulate the immune system through nutrition. This is what I call "Nutritional Immunotherapy", which simply means targeting the immune system with nutritional tools for treating inflammatory and autoimmune diseases. </span></div>
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<span style="font-family: 'Trebuchet MS', sans-serif;">Nutrition acts both directly and indirectly on the immune system, as shown in the following diagram:</span><br />
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<tr><td class="tr-caption" style="text-align: center;"><b>Relationship between nutrition and the immune system.</b> See text for details.</td></tr>
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<li><span style="font-family: 'Trebuchet MS', sans-serif;"><u style="font-weight: bold;">Nutrition influences the composition and function of adipose tissue (AT):</u> Energy intake regulates fat mass, affecting the function and differentiation of pre- and mature adipocytes (direct effect). The concentration of specific fatty acids in AT is proportional to their abundance in the diet (indirect effect). The dietary fatty acid profile also affects membrane lipid composition on other cell types, which regulates cell functioning. </span></li>
<li><span style="font-family: 'Trebuchet MS', sans-serif;"><b style="text-decoration: underline;">Adipose tissue is an immune organ:</b> There are several immune cells present in AT from different body sites, differing each one in the proportion of cell types. Lymph nodes present in AT are sorrounded by perinodal adipocytes, which have a higher proportion of polyunsaturated fatty acids (PUFA) than adipocytes far from the nodes. Lymphoid clusters within AT include milky spots (MS) and fat-associated lymphoid clusters (FALCs), which have an active role determining whole-body immune responses. Adipocytes are also able to secrete adipocytokines (leptin, resistin, adiponectin, etc.) and classical cytokines (IL-6, TNF-a, etc.). </span></li>
<li><span style="font-family: 'Trebuchet MS', sans-serif;"><u style="font-weight: bold;">Adipose tissue regulates energy intake:</u> Cytokines secreted by AT regulate appetite and energy balance, acting through neural pathways involved in energy homeostasis.</span></li>
<li><span style="font-family: 'Trebuchet MS', sans-serif;"><u style="font-weight: bold;">Nutrition affects the gut flora:</u> Microbial composition of the human gut flora is very responsive to diet. Small changes in either macronutrient distribution or food choices affect differently not only the relative proportion of certain species, but also their metabolism and gene expression patterns.</span></li>
<li><span style="font-family: 'Trebuchet MS', sans-serif;"><u style="font-weight: bold;">Gut flora regulates fat mass and metabolism:</u> Digestion of plant cell walls, oligosaccharides and other food components by gut bacteria increases the energy yield of food, contributing to energy intake. Acetate and propionate, produced by the fermentation of soluble fiber, are metabolized (predominantly) in skeletal muscle and the liver, respectively. Gut microbiota also supress FIAF activity and promotes hepatic triglyceride synthesis. Metabolism of drugs and xenobiotics is dependent on the composition of the gut flora. </span></li>
<li><u style="font-family: 'Trebuchet MS', sans-serif; font-weight: bold;">Gut flora regulates immunity:</u><span style="font-family: 'Trebuchet MS', sans-serif;"> The presence of specific bacteria shapes the immune system and regulates mucosal and peripheral immune responses. The gut flora also competes with enteropathogens directly and by the action of antimicrobial peptides. Evolutionary co-adaptation has given gut bacteria and other microorganisms essential roles for mammalian health. </span></li>
<li><span style="font-family: 'Trebuchet MS', sans-serif;"><u style="font-weight: bold;">Nutrition regulates immunity:</u> Energy availability and macronutrients regulate the function, maturation and differentiation of immune cells. </span></li>
</ol>
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<span style="font-family: 'Trebuchet MS', sans-serif;">Nutrition has the potential to act on all levels mentioned above. This is why a good diet is very important not only for prevention, but also for treatment of diseases of civilization.</span></div>
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<span style="font-family: 'Trebuchet MS', sans-serif;"><b><u>Important components</u></b></span></div>
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<span style="font-family: 'Trebuchet MS', sans-serif;"><b><u><br /></u></b></span></div>
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<span style="font-family: 'Trebuchet MS', sans-serif;">The nutritional immunotherapy protocol integrates concepts from immunology, molecular and evolutionary biology. The first two help us answer the "how" question, while the latter helps us understand the "why". </span></div>
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<span style="font-family: 'Trebuchet MS', sans-serif;">What differences this protocol from other diets is that it takes into account the fact that people who already have developed an inflammatory and/or autoimmune disorder respond differently to any diet. This means that the response to a diet is individual, and more importantly, in this case, the starting point is not a natural one. This point is important for understanding the recommendations given hereafter. </span></div>
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<span style="font-family: 'Trebuchet MS', sans-serif;">The history of the patient, specially those aspects that would compromise the response to certain macronutrients and the normal development of a tolerant immune system, needs to be addressed before trying to make any nutritional adjustment. Nowadays, with genetic tools (like <a href="https://www.23andme.com/">23andMe</a>), tailoring the diet according to the genotype is possible and helpful. </span></div>
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<span style="font-family: 'Trebuchet MS', sans-serif;"><br /></span></div>
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<span style="font-family: 'Trebuchet MS', sans-serif;">Important factors for the success and application of the protocol are shown below.</span></div>
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<b><span style="font-family: 'Trebuchet MS', sans-serif;">Relevant factors
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<td nowrap="" style="border-top: none; border: solid windowtext 1.0pt; height: 16.5pt; mso-border-bottom-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-right-alt: solid windowtext .5pt; padding: 0cm 5.4pt 0cm 5.4pt; width: 182.0pt;" valign="bottom" width="243">
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="font-family: 'Trebuchet MS', sans-serif;">Mode of birth<o:p></o:p></span></div>
</td>
</tr>
<tr style="height: 16.5pt; mso-yfti-irow: 2;">
<td nowrap="" style="border-top: none; border: solid windowtext 1.0pt; height: 16.5pt; mso-border-bottom-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-right-alt: solid windowtext .5pt; padding: 0cm 5.4pt 0cm 5.4pt; width: 182.0pt;" valign="bottom" width="243">
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="font-family: 'Trebuchet MS', sans-serif;">Hygiene practices during childhood</span></div>
</td>
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<tr style="height: 16.5pt; mso-yfti-irow: 3;">
<td nowrap="" style="border-top: none; border: solid windowtext 1.0pt; height: 16.5pt; mso-border-bottom-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-right-alt: solid windowtext .5pt; padding: 0cm 5.4pt 0cm 5.4pt; width: 182.0pt;" valign="bottom" width="243">
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="font-family: 'Trebuchet MS', sans-serif;">Family diet, diet history and maternal environment</span> <span style="font-family: 'Trebuchet MS', sans-serif;"><br /></span></div>
</td>
</tr>
<tr style="height: 16.5pt; mso-yfti-irow: 4;">
<td nowrap="" style="border-top: none; border: solid windowtext 1.0pt; height: 16.5pt; mso-border-bottom-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-right-alt: solid windowtext .5pt; padding: 0cm 5.4pt 0cm 5.4pt; width: 182.0pt;" valign="bottom" width="243">
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="font-family: 'Trebuchet MS', sans-serif;">Medical history<o:p></o:p></span></div>
</td>
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<tr style="height: 16.5pt; mso-yfti-irow: 5;">
<td nowrap="" style="border-top: none; border: solid windowtext 1.0pt; height: 16.5pt; mso-border-bottom-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-right-alt: solid windowtext .5pt; padding: 0cm 5.4pt 0cm 5.4pt; width: 182.0pt;" valign="bottom" width="243">
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<span style="font-family: 'Trebuchet MS', sans-serif;">Genotype<o:p></o:p></span></div>
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<tr style="height: 16.5pt; mso-yfti-irow: 6;">
<td nowrap="" style="border-top: none; border: solid windowtext 1.0pt; height: 16.5pt; mso-border-bottom-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-right-alt: solid windowtext .5pt; padding: 0cm 5.4pt 0cm 5.4pt; width: 182.0pt;" valign="bottom" width="243">
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="font-family: 'Trebuchet MS', sans-serif;">Social/lifestyle
experiences<o:p></o:p></span></div>
</td>
</tr>
<tr style="height: 16.5pt; mso-yfti-irow: 7;">
<td nowrap="" style="border-top: none; border: solid windowtext 1.0pt; height: 16.5pt; mso-border-bottom-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-right-alt: solid windowtext .5pt; padding: 0cm 5.4pt 0cm 5.4pt; width: 182.0pt;" valign="bottom" width="243">
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<span style="font-family: 'Trebuchet MS', sans-serif;">Symptoms<o:p></o:p></span></div>
</td>
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<tr style="height: 16.5pt; mso-yfti-irow: 8;">
<td nowrap="" style="border-top: none; border: solid windowtext 1.0pt; height: 16.5pt; mso-border-bottom-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-right-alt: solid windowtext .5pt; padding: 0cm 5.4pt 0cm 5.4pt; width: 182.0pt;" valign="bottom" width="243">
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="font-family: 'Trebuchet MS', sans-serif;">Self-assessment<o:p></o:p></span></div>
</td>
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<tr style="height: 16.5pt; mso-yfti-irow: 9; mso-yfti-lastrow: yes;">
<td nowrap="" style="border-top: none; border: solid windowtext 1.0pt; height: 16.5pt; mso-border-bottom-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-right-alt: solid windowtext .5pt; padding: 0cm 5.4pt 0cm 5.4pt; width: 182.0pt;" valign="bottom" width="243">
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="font-family: 'Trebuchet MS', sans-serif;">Bloodwork<o:p></o:p></span></div>
</td>
</tr>
</tbody></table>
</div>
<div>
<span style="font-family: 'Trebuchet MS', sans-serif;"><br /></span></div>
<div>
<span style="font-family: 'Trebuchet MS', sans-serif;"> <u>Mode of birth</u></span></div>
<div>
<span style="font-family: 'Trebuchet MS', sans-serif;"><u><br /></u></span></div>
<div>
<span style="font-family: 'Trebuchet MS', sans-serif;">This important but commonly overlooked factor is determinant for immune development and future health. Vaginal birth is the natural mode of birth because it stimulates not only hormonal responses in the mother and the child, but because it promotes an adequate colonization of the neonate, one that we have been adapted for. At birth, the newborn is sterile*, so it can be colonized virtually by any species. Babies born by cesarean section have an abnormal microbiota, as they harbor bacteria from the hospital's environment, medical practitioners and the mother's skin. Normally, during the passage through the birth canal, the infant is exposed to vaginal and cervical flora. Because of its proximity, newborns are also rapidly colonized by maternal gut microbiota, which seems to be the predominant source of bacteria. Pre-term infants also display a different pattern of microbial colonization.</span></div>
<div>
<span style="font-family: 'Trebuchet MS', sans-serif;"><br /></span></div>
<div>
<u><span style="font-family: 'Trebuchet MS', sans-serif;">Hygiene practices during childhood</span> </u><span style="font-family: 'Trebuchet MS', sans-serif;"><br /></span></div>
<div>
<span style="font-family: 'Trebuchet MS', sans-serif;"><br /></span></div>
<div>
<span style="font-family: 'Trebuchet MS', sans-serif;">Gut development is a continuous process that has its last phase during late infancy/early childhood, as the child transitions from breastmilk to complementary foods. Exclusive breastfeeding (and ingestion of colostrum) is very important for preventing inadequate colonization, as it has bacteria, immune and growth factors which promote immune development. Breastmilk also has a perfect nutritional composition, with oligosaccharides (and other components) that promote the growth and establishment of commensal bacteria (predominately Bifidobacteria). </span><span style="font-family: 'Trebuchet MS', sans-serif;">Formula-fed infants display an aberrant gut microbiota and normal colonization is severly delayed (if not completely disrupted).</span></div>
<div>
<span style="font-family: 'Trebuchet MS', sans-serif;"><br /></span></div>
<div>
<span style="font-family: 'Trebuchet MS', sans-serif;">Microbial exposure favors diversification and exposure to pathogens, which is necessary for stimulation of immune memory and tolerance. Contact with animals, eating raw food and playing in the dirt are a necessary part of a healthy lifestyle in infancy. Excessive hygiene and antibiotic use promote dysbiosis. </span></div>
<div>
<span style="font-family: 'Trebuchet MS', sans-serif;"><br /></span></div>
<div>
<span style="font-family: 'Trebuchet MS', sans-serif;"><u>Family diet, diet history and maternal environment</u></span> </div>
<div>
<br /></div>
<div>
<span style="font-family: 'Trebuchet MS', sans-serif;">The diet eaten by your father, mother and grandparents influences the expression of genes involved in energy metabolism. These effects are transmitted intergenerationally and lasting during adulthood. Inadequate dietary patterns followed during childhood and adulthood worsen immune and metabolic function. Additionally, maternal status during pregnancy (stress, nutrition, etc.) has profound effects on many genes. </span></div>
<div>
<span style="font-family: 'Trebuchet MS', sans-serif;"><br /></span></div>
<div>
<span style="font-family: 'Trebuchet MS', sans-serif;"><u>Medical history</u></span> <span style="font-family: 'Trebuchet MS', sans-serif;"><br /></span></div>
<div>
<span style="font-family: 'Trebuchet MS', sans-serif;"><br /></span></div>
<div>
<span style="font-family: 'Trebuchet MS', sans-serif;">Previous diseases, antibiotic abuse and utilization of other substances can influence both the normal functioning of the immune system as well as metabolism.</span></div>
<div>
<span style="font-family: 'Trebuchet MS', sans-serif;"><br /></span></div>
<div>
<span style="font-family: 'Trebuchet MS', sans-serif;"><u>Genotype</u></span> <span style="font-family: 'Trebuchet MS', sans-serif;"><br /></span></div>
<div>
<span style="font-family: 'Trebuchet MS', sans-serif;"><br /></span></div>
<div>
<span style="font-family: 'Trebuchet MS', sans-serif;">The presence of certain alleles are important for tolerance of specific food components (ie. lactose) and variability in immune responses (ie. MHC alleles, cytokine gene polymorphism).</span></div>
<div>
<span style="font-family: 'Trebuchet MS', sans-serif;"><br /></span></div>
<div>
<span style="font-family: 'Trebuchet MS', sans-serif;"><u>Social/lifestyle experiences</u></span> <span style="font-family: 'Trebuchet MS', sans-serif;"><br /></span></div>
<div>
<span style="font-family: 'Trebuchet MS', sans-serif;"><br /></span></div>
<div>
<span style="font-family: 'Trebuchet MS', sans-serif;">Having bad social relationships, lack of optimism, stress and other common lifestyle experiences affect the inflammatory status of the body. For example, losing a game in very competitive persons increases the levels of inflammatory cytokines higher than in non-competitive subjects. Mental stress also seem to affect the composition of the gut microbiota and gut permeability. </span></div>
<div>
<span style="font-family: 'Trebuchet MS', sans-serif;"><br /></span></div>
<div>
<span style="font-family: 'Trebuchet MS', sans-serif;"><u>Symptoms, self-assessment and bloodwork</u></span><span style="font-family: 'Trebuchet MS', sans-serif;"><br /></span></div>
<div>
<span style="font-family: 'Trebuchet MS', sans-serif;"><br /></span></div>
<div>
<span style="font-family: 'Trebuchet MS', sans-serif;">Any symptom (either bad or good) is valuable for trying to identify potential problems. Self-assessment, including anthropometric measures, emotional status or the characteristics of feces can also help narrowing the spectrum of possible disorders. Bloodwork and biomarkers are helpful for confirming assumptions and health status.</span></div>
<div>
<span style="font-family: 'Trebuchet MS', sans-serif;"><br /></span></div>
<div>
<span style="font-family: 'Trebuchet MS', sans-serif;"><b><u>Summary</u></b></span></div>
<div>
<span style="font-family: 'Trebuchet MS', sans-serif;"><br /></span></div>
<div>
<span style="font-family: 'Trebuchet MS', sans-serif;">Before beginning any nutritional therapy, it is important to check for past events and factors that affect the metabolic and immune status. This will aid in finding the right dietary composition that helps the most with a given problem and reducing the time of experimentation needed for finding the adequate nutrition and supplementation for an individual. </span></div>
<div>
<span style="font-family: 'Trebuchet MS', sans-serif;"><br /></span></div>
<div>
<span style="font-family: 'Trebuchet MS', sans-serif;">*Although recent evidence suggests that bacteria colonize the gut <i>in uterus</i>.</span></div>
<div>
<span style="font-family: 'Trebuchet MS', sans-serif;"><br /></span></div>
</div>Anonymousnoreply@blogger.com11tag:blogger.com,1999:blog-4724838399830873886.post-29929904837601746982012-03-12T12:57:00.002-07:002017-03-13T06:07:40.195-07:00Human microbiota and atherosclerosis<div style="text-align: justify;">
<span style="font-family: 'Trebuchet MS', sans-serif;">I've been wanting to post about <a href="http://www.ncbi.nlm.nih.gov/pubmed/20937873">this</a> study for a while now. I think its a good update while I finish my first post on my nutritional immunotherapy protocol. This study was performed given the preliminary evidence linking infections and atherosclerosis, and the association of the human microbiota with the atherosclerotic plaque. For example, bacterial DNA has been observed in atherosclerotic plaques from young and old subjects (<a href="http://www.ncbi.nlm.nih.gov/pubmed/16513386">1</a>, <a href="http://www.ncbi.nlm.nih.gov/pubmed/12627283">2</a>). This relationship has been investigated with more focus on oral bacteria, due to the association of periodontal disease and cardiovascular disease (CVD) (<a href="http://www.ncbi.nlm.nih.gov/pubmed/20367093">3</a>, <a href="http://www.ncbi.nlm.nih.gov/pubmed/17012731">4</a>) and the presence of periodontal pathogens in atherosclerotic plaques (<a href="http://www.ncbi.nlm.nih.gov/pubmed/11063387">5</a>). </span></div>
<div style="text-align: justify;">
<span style="font-family: 'Trebuchet MS', sans-serif;"><br /></span></div>
<div style="text-align: justify;">
<span style="font-family: 'Trebuchet MS', sans-serif;">The authors tried to answer the following questions:</span></div>
<div style="text-align: justify;">
<span style="font-family: 'Trebuchet MS', sans-serif;"><br /></span></div>
<div style="text-align: justify;">
<span style="font-family: 'Trebuchet MS', sans-serif;"></span></div>
<div style="text-align: justify;">
<span style="font-family: 'Trebuchet MS', sans-serif;">Is there a core atherosclerotic plaque microbiota? </span></div>
<div style="text-align: justify;">
<span style="font-family: 'Trebuchet MS', sans-serif;">Are bacteria present in the plaque also detectable in the oral cavities or guts of the same individuals?</span></div>
<div style="text-align: justify;">
<span style="font-family: 'Trebuchet MS', sans-serif;">Do the microbiotas of the oral cavity, gut, and atherosclerotic plaque relate to disease markers such as plasma levels of apolipoproteins and cholesterol? </span></div>
<div style="text-align: justify;">
<span style="font-family: 'Trebuchet MS', sans-serif;">Is an altered oral or fecal microbiota associated with atherosclerosis?</span></div>
<div style="text-align: justify;">
<span style="font-family: 'Trebuchet MS', sans-serif;"><br /></span></div>
<div style="text-align: justify;">
<span style="font-family: 'Trebuchet MS', sans-serif;">Using <a href="http://en.wikipedia.org/wiki/16S_ribosomal_RNA">16S rRNA</a> sequences (from patients with clinical atherosclerosis and controls) and the unweighted <a href="http://bmf.colorado.edu/unifrac/">UniFrac distance metric</a> (qualitative instead of quantitative), they found strong clustering of samples according to body site, suggesting that the oral, gut and atherosclerotic plaque (AP) sites have different microbial communities:</span></div>
<span style="font-family: 'Trebuchet MS', sans-serif;"><br /></span><br />
<div class="separator" style="clear: both; text-align: center;">
<span style="font-family: 'Trebuchet MS', sans-serif;"><a href="http://www.pnas.org/content/108/suppl.1/4592/F1.medium.gif" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="283" src="http://www.pnas.org/content/108/suppl.1/4592/F1.medium.gif" width="320" /></a></span></div>
<span style="font-family: 'Trebuchet MS', sans-serif;"><br /></span><br />
<div style="text-align: justify;">
<span style="font-family: 'Trebuchet MS', sans-serif;">PC1 and PC2 refer to the first two principal coordinates from the principal coordinate analysis of unweighted UniFrac, plotted for each sample (See also <a href="http://www.pnas.org/content/suppl/2010/10/05/1011383107.DCSupplemental/pnas.201011383SI.pdf#nameddest=SF1">Fig S1</a>). Of these sites, bacterial diversity was higher for the gut microbiota. </span></div>
<div style="text-align: justify;">
<span style="font-family: 'Trebuchet MS', sans-serif;"><br /></span></div>
<div style="text-align: justify;">
<span style="font-family: 'Trebuchet MS', sans-serif;">The analysis of the atherosclerotic plaque microbiota revealed that there was a positive correlation between the amount of bacterial 16S rRNA and the number of leukocytes present in the AP, and there was significantly higher levels of Proteobacteria and fewer Firmicutes compared with the oral and gut samples. Supporting the role for a "core" AP microbiota, several <a href="http://en.wiktionary.org/wiki/operational_taxonomic_unit">OTUs</a> were present in all AP samples, which differentiated these samples from oral or fecal samples: <i>Chryseomonas </i>was detected at high levels in the AP samples, but not in gut or oral samples, being the most discriminative genus between sites and driving the differences between body sites. Other OTUs, three for the genus <i>Staphylococcus</i>, three classified as Propionibacterineae and one belonging to the genus <i>Burkholderia</i>, were specific for AP samples and were present in all AP samples analyzed.</span></div>
<div style="text-align: justify;">
<span style="font-family: 'Trebuchet MS', sans-serif;"><br /></span></div>
<div style="text-align: justify;">
<span style="font-family: 'Trebuchet MS', sans-serif;">There were no OTUs differentiating oral samples from healthy subjects and patients, but there were correlations between the abundances of OTUs in the oral cavity and CVD markers: the abundance of <i>Fusobacterium</i> was positively correlated with levels of cholesterol (P = 0.028) and LDL (P = 0.005), the abundance of <i>Streptococcus</i> was positively correlated to HDL (P = 0.0001) and ApoAI (P = 0.01) levels and the abundance of <i>Neisseria</i> was negatively correlated to levels of these last two markers (P = 0.02 and 0.005, respectively). This is interesting, given that Fusobacterium has been associated with periodontal disease (<a href="http://www.ncbi.nlm.nih.gov/pubmed/21220789">6</a>). As with oral samples, there were no differentiating OTUs between gut samples from controls and patients (in terms of OTU abundances). In gut samples, the abundance of two OTUs classified as uncharacterized members of Erysipelotrichaceae and Lachnospiraceae families were positively correlated with cholesterol (P = 0.009 and 0.001, respectively) and LDL (P = 0.012 and 0.007, respectively). </span></div>
<div style="text-align: justify;">
<span style="font-family: 'Trebuchet MS', sans-serif;"><br /></span></div>
<div style="text-align: justify;">
<span style="font-family: 'Trebuchet MS', sans-serif;">Finally, inter-individual comparisons between sites showed that some OTUs were shared among sites. These included OTUs for <i>Veillonella</i> (in AP and oral samples in 11 of 13 patients, detected also in the gut sample of two patients) and <i>Streptococcus</i> (in AP and oral samples in 6 of 10 patients, detected also in the gut of four patients). Within patients, the AP samples contained OTUs shared with oral (<i>Propionibacterium</i>, <i>Rothia</i>, <i>Burkholderia</i>, <i>Corynebacterium</i>, <i>Granulicatella</i>, <i>Staphylococcus</i>) and gut (<i>Bacteroides</i>, <i>Bryantella</i>, <i>Enterobacter</i>, <i>Ruminococcus</i>) samples. </span></div>
<div style="text-align: justify;">
<span style="font-family: 'Trebuchet MS', sans-serif;"><br /></span></div>
<span style="font-family: 'Trebuchet MS', sans-serif;"><b><u>Summary</u></b></span><br />
<ul>
<li style="text-align: justify;"><span style="font-family: 'Trebuchet MS', sans-serif;">The study identified a "core" atherosclerotic plaque microbiota, comprising higher levels of Proteobacteria and fewer Firmicutes, compared with the gut and oral samples. </span></li>
<li style="text-align: justify;"><span style="font-family: 'Trebuchet MS', sans-serif;">The AP microbiota contained specific OTUs not shared with the analyzed body sites.</span></li>
<li style="text-align: justify;"><span style="font-family: 'Trebuchet MS', sans-serif;">The abundance of some OTUs in the gut and oral cavity was correlated with CVD markers. </span></li>
<li style="text-align: justify;"><span style="font-family: 'Trebuchet MS', sans-serif;">Shared OTUs among sites included <i>Streptococcus</i> and <i>Veillonella</i>, the correlation being stronger among the oral cavity and the AP, and these OTUs were also found in the gut samples from some patients. Across patients, the abundance of both were correlated in the oral cavity and the AP.</span></li>
</ul>
<div>
<span style="font-family: 'Trebuchet MS', sans-serif;"><b><u>Commentary</u></b></span></div>
<div>
<span style="font-family: 'Trebuchet MS', sans-serif;"><b><u><br /></u></b></span></div>
<div>
<div style="text-align: justify;">
<span style="font-family: 'Trebuchet MS', sans-serif;">I find this study very interesting because it supports the role of infection on the pathogenesis of atherosclerosis and CVD. The "infection hypothesis" of atherosclerosis has been proposed before (<a href="http://www.spacedoc.com/uffe_ravnskov_real_cause_heart_disease_3">7</a>). The fact that specific bacteria is present in AP and not in other body sites analyzed and that the amount of bacterial 16S rRNA was positively correlated with leukocyte counts, support the notion that these pathogens support directly atherosclerosis progression. However, the study only analyzed the oral cavity and the gut, so it is impossible to conclude that these pathogens couldnt have been derived from other body sites (for example, the skin). Moreover, primers commonly utilized to amplify 16S rRNA sequences are limited to some species, an inherent property of the method (<a href="http://www.ncbi.nlm.nih.gov/pubmed/18463690">8</a>). Nevertheless, it seems more feasible to suppose that the origin of AP bacteria is the oral cavity because of the close proximity of the bacterial communities in the mouth to the highly vascularized gingival lining and because of the thickness of the subgingival epithelium, which differs from other protective layers such as the skin or the gut mucosa (<a href="http://www.ncbi.nlm.nih.gov/pubmed/19136433">9</a>). Accordingly, any mechanical disruption of oral bacterial biofilms can trigger bacteremia, and these include oral procedures (periodontal probing, tooth extractions, etc), oral hygiene activities (such as brushing) and physiological phenomena (like chewing) (<a href="http://www.ncbi.nlm.nih.gov/pubmed/19136433">9</a>). This, coupled with the findings that the abundance of OTUs in the AP were correlated with that of the oral cavity support this hypothesis. Gut bacterial origin is more complicated but feasible (as shown by the presence of gut bacteria in AP samples). The authors suggest that one possible way of this transfer is by phagocytosis of macrophages at epithelial linings. </span></div>
</div>
<div>
<span style="font-family: 'Trebuchet MS', sans-serif;"><br /></span></div>
<div>
<div style="text-align: justify;">
<span style="font-family: 'Trebuchet MS', sans-serif;">If indeed bacteria play a role in the formation and/or progression of atherosclerosis, the million dollar question is why do these specific pathogens adhere to the vascular endothelium? Moreover, is this colonization the initial trigger for the localized inflammatory response or just aggravates the condition? With the available evidence it is hard to answer these questions. It has been proposed that atheromas might act as mechanical sieves, collecting bacteria from the cirulation (<a href="http://www.ncbi.nlm.nih.gov/pubmed/16490835">10</a>). This would have deleterious consequences, as bacterial accumulation in the AP would lead to an increased inflammatory response. It could also link the fact that endotoxemia increases the risk of CVD (<a href="http://www.ncbi.nlm.nih.gov/pubmed/10588212">11</a>), for which periodontal pathogens seem to play an important role (<a href="http://www.ncbi.nlm.nih.gov/pubmed/17363692">12</a>). Supporting the role of infection as secondary to atherosclerotic inflammation, fungal DNA has been observed in AP (<a href="http://www.ncbi.nlm.nih.gov/pubmed/17991032">13</a>), with some species correlated with that found on human microbial communities. It is of worth noting that in this study, fungal richness was not associated with classical CVD risk factors. Because not all normal residing oral bacteria are found in AP samples, AP invasion might be related to the virulence properties of some species </span><span style="font-family: 'Trebuchet MS', sans-serif;">(</span><a href="http://www.ncbi.nlm.nih.gov/pubmed/19136433" style="font-family: 'Trebuchet MS', sans-serif;">9</a><span style="font-family: 'Trebuchet MS', sans-serif;">). This seems to be the case, as in the study reviewed here, there was a common abundance of <i>Streptococcus</i> and <i>Veillonella</i> in AP samples. <i>Streptococcus</i> is able to adhere to the endothelium, while <i>Veillonella</i> is able to change its adherence capacity in the presence of some factors from <i>Streptococcus</i> (<a href="http://www.ncbi.nlm.nih.gov/pubmed/591064/">14</a>). In fact, there is a tight relationship between <i>Streptococcus</i> and <i>Veillonella</i> in the oral cavity as some strains co-aggregate, partially because <i>Veillonella</i> seems to be metabolically dependent on <i>Streptococcus</i> (<a href="http://www.ncbi.nlm.nih.gov/pubmed/18805978/">15</a>). This relationship is so important that <i>Veillonella</i> is unable to establish an infection without <i>Streptococcus</i>.</span></div>
</div>
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<div style="text-align: justify;">
<span style="font-family: 'Trebuchet MS', sans-serif;">In conclusion, microbial accumulation in AP might contribute to the progression of atherosclerosis. Although the mechanism by which these microorganisms colonize this site is not defined, it is clear that several microbes found in other body sites are also found in AP, which suggests that the normal human microbial communities are an important source of pathogens contributing to atherosclerosis progression. Translocation from these sites, in turn, is controlled by the host inflammatory status. This seems to be relevant to translocation from the oral cavity: transient bacteremia is experienced by everyone because of mechanical disruption of microbial biofilms (for instance, when eating), but it is controlled quickly. However, there are always some persisters which resist by-standing immune mechanisms. Obviously, a higher microbial load facilitates dissemination into the bloodstream and could possible influence the degree of transient bacteremia. A higher bacterial load coupled with a compromised subgingival epithelium barrier increases the risk of bacteremia and secondary colonization. So, in order to reduce the risk of AP colonization by oral pathogens, it is wise to target these two factors. For reducing oral bacterial load (overgrowth), reducing sucrose intake might be of benefit, as bacterial glucosyltransferase (GTF) plays a crucial role in plaque formation (<a href="http://www.ncbi.nlm.nih.gov/pubmed/3159073">16</a>) and <i><a href="http://en.wikipedia.org/wiki/Streptococcus_mutans">S.mutans</a> </i>is only pathogenic in the presence of sucrose (<a href="http://www.ncbi.nlm.nih.gov/pubmed/2523085">17</a>). Dietary sucrose has been shown to increase total viable microbial density and <i>S.mutans</i> population in human dental plaque (<a href="http://www.ncbi.nlm.nih.gov/pubmed/1057572">18</a>). Sucrose alone seem to be more cariogenic than sucrose plus fructose (<a href="http://www.ncbi.nlm.nih.gov/pubmed/11093024">19</a>, <a href="http://www.ncbi.nlm.nih.gov/pubmed/9286518">20</a>). Additionally, sucrose alters the ionic concentration in the biofilms' matrix, altering the normal de- and re-mineralization process of enamel and dentin (<a href="http://www.ncbi.nlm.nih.gov/pubmed/16998125/">21</a>). The role of starches in dental plaque formation is controversial (<a href="http://www.ncbi.nlm.nih.gov/pubmed/11021636">22</a>), although some authors are in agreement with the Cleave & Yudkin hypothesis, which states that an excess of fermentable carbohydrate intake (in the absence of dental interventions) promotes dental diseases and then systemic diseases (<a href="http://www.ncbi.nlm.nih.gov/pubmed/19587153">23</a>). Nevertheless, starchy foods commonly ate might promote dental plaque formation and disease. Pollard (<a href="http://www.ncbi.nlm.nih.gov/pubmed/7867054">24</a>) showed that cornflakes, branflakes and wholemeal bread produced the minimum dental plaque pH peak, while all foods tested promoted enamel demineralization*. This might be related to the fact that, although starches can reduce plaque pH and induce demineralization, sucrose accelerates this effects (<a href="http://www.ncbi.nlm.nih.gov/pubmed/8069887">25</a>). This is probably mediated by the interaction between bacterial GTF and salivary amylase (<a href="http://www.ncbi.nlm.nih.gov/pubmed/19028906/">26</a>). </span><span style="font-family: 'Trebuchet MS', sans-serif;">In contrast to what some might expect, </span><span style="font-family: 'Trebuchet MS', sans-serif;">whole </span><span style="font-family: 'Trebuchet MS', sans-serif;">fruit and fruit juices induce enamel demineralization by the same magnitude (<a href="http://www.ncbi.nlm.nih.gov/pubmed/21876354">27</a>). This has been also found in some observational studies, where high fruit consumption is associated with increased caries risk (<a href="http://www.ncbi.nlm.nih.gov/pubmed/22298516">28</a>). On the contrary, cheese and nuts have shown a negative association (<a href="http://www.ncbi.nlm.nih.gov/pubmed/18781067">29</a>). Finally, inflammation increases the risk of oral bacterial growth and translocation, which might induce and/or aggravate systemic diseases (<a href="http://www.ncbi.nlm.nih.gov/pubmed/16848982">30</a>). Periodontal disease has been positively associated with obesity (<a href="http://www.ncbi.nlm.nih.gov/pubmed/20722533">31</a>), metabolic syndrome (<a href="http://www.ncbi.nlm.nih.gov/pubmed/20887511">32</a>), type 2 diabetes (<a href="http://www.ncbi.nlm.nih.gov/pubmed/18390797">33</a>), Alzheimer's disease (<a href="http://www.ncbi.nlm.nih.gov/pubmed/18631974">34</a>), among other. Thus, controlling inflammation is key to avoid secondary diseases caused by pathogenic oral bacteria. </span></div>
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<span style="font-family: 'Trebuchet MS', sans-serif;">* "</span><span style="background-color: white; line-height: 17px; text-align: left;"><span style="font-family: 'Trebuchet MS', sans-serif;">Test foods were oranges, apples, bananas, Cornflakes, Branflakes, Weetabix, Alpen (no added sugar), white bread, wholemeal bread, rice, and spaghetti, with positive and negative controls of sucrose and sorbitol."</span></span></div>
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<span style="float: left; padding-bottom: 5px; padding-left: 5px; padding-right: 5px; padding-top: 5px;"><a href="http://www.researchblogging.org/"><img alt="ResearchBlogging.org" src="http://www.researchblogging.org/public/citation_icons/rb2_large_gray.png" style="border: 0;" /></a></span><span class="Z3988" title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.jtitle=Proceedings+of+the+National+Academy+of+Sciences+of+the+United+States+of+America&rft_id=info%3Apmid%2F20937873&rfr_id=info%3Asid%2Fresearchblogging.org&rft.atitle=Human+oral%2C+gut%2C+and+plaque+microbiota+in+patients+with+atherosclerosis.&rft.issn=0027-8424&rft.date=2011&rft.volume=108+Suppl+1&rft.issue=&rft.spage=4592&rft.epage=8&rft.artnum=&rft.au=Koren+O&rft.au=Spor+A&rft.au=Felin+J&rft.au=F%C3%A5k+F&rft.au=Stombaugh+J&rft.au=Tremaroli+V&rft.au=Behre+CJ&rft.au=Knight+R&rft.au=Fagerberg+B&rft.au=Ley+RE&rft.au=B%C3%A4ckhed+F&rfe_dat=bpr3.included=1;bpr3.tags=Biology%2CMedicine%2CHealth%2CNutrition%2C+Immunology%2C+Molecular+Biology%2C+Microbiology">Koren O, Spor A, Felin J, Fåk F, Stombaugh J, Tremaroli V, Behre CJ, Knight R, Fagerberg B, Ley RE, & Bäckhed F (2011). Human oral, gut, and plaque microbiota in patients with atherosclerosis. <span style="font-style: italic;">Proceedings of the National Academy of Sciences of the United States of America, 108 Suppl 1</span>, 4592-8 PMID: <a href="http://www.ncbi.nlm.nih.gov/pubmed/20937873" rev="review">20937873</a></span>Anonymousnoreply@blogger.com17tag:blogger.com,1999:blog-4724838399830873886.post-83434771161894261122012-02-21T21:58:00.002-08:002017-03-13T06:07:40.227-07:00Adipose tissue & Immunity: The basics 2<div style="text-align: justify;">
<span style="font-family: 'Trebuchet MS', sans-serif;"><b><u>Lymphoid structures in adipose tissue</u></b></span><br />
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<span style="font-family: 'Trebuchet MS', sans-serif;">Leukocytes present in the <a href="http://en.wikipedia.org/wiki/Greater_omentum">omentum</a> are organized in clusters called "milky spots" (MS), which composition varies between species and is determined by antigenic exposure. The omentum has immunological and wound-healing properties, probably due to its angiogenic potential, large surface area and immunological activity (<a href="http://www.ncbi.nlm.nih.gov/pubmed/19427241">1</a>). MS are composed primarily of macrophages and B1 cells. B1 cells are a subset of B cells that are different from conventional B cells (B2) in that they express different markers and antigen receptors that can bind common bacterial epitopes. These cells are also able to produce natural antibodies that provide a first protection to bacterial infections (<a href="http://www.ncbi.nlm.nih.gov/pubmed/19464991">2</a>). The importance of MS as secondary lymphoid organs was highlighted by the work of Rangel-Moreno, et al. (<a href="http://www.ncbi.nlm.nih.gov/pubmed/19427241">3</a>). They showed that SLP mice (spleen lymph node and Peyer's patch deficient) are able to generate B-cell responses to peritoneal antigens and present MS, which develop in the absence of LTi (lymphoid tissue inducer) cells. The local role for MS seems to be presenting </span><span style="font-family: 'Trebuchet MS', sans-serif;"> </span><span style="font-family: 'Trebuchet MS', sans-serif;">antigens derived from the peritoneal cavity to</span><span style="font-family: 'Trebuchet MS', sans-serif;"> recirculating T and B lymphocytes, which enter MS from the blood. MS could also support <a href="http://en.wikipedia.org/wiki/Somatic_hypermutation">somatic hypermutation</a> and <a href="http://en.wikipedia.org/wiki/Affinity_maturation">affinity maturation</a> of B cells, and proliferation of T cells. Lymphocytes activated elsewhere were also found in MS, supporting the view of MS as an important part of the immune system. </span></div>
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<span style="font-family: 'Trebuchet MS', sans-serif;">In the human <a href="http://en.wikipedia.org/wiki/Mesentery">mesentery</a>, there is the presence of lymphoid clusters similar to MS called FALCs (fat-associated lymphoid clusters), in that both contain lymphocytes framed by adipose tissue in the peritoneal cavity. However, FALCs contain a great number (20-40% of total lymphocytes) of </span><span style="font-family: 'Trebuchet MS', sans-serif;">Lin- </span><span style="font-family: 'Trebuchet MS', sans-serif;">c-Kit+ Sca-1+ cells (</span><a href="http://www.ncbi.nlm.nih.gov/pubmed/20023630" style="font-family: 'Trebuchet MS', sans-serif;">4</a><span style="font-family: 'Trebuchet MS', sans-serif;">)*, which also express ILR7a. This suggests a progenitor potential. Moreover, these cells are capable of producing large amounts of IL2, IL4, IL5, IL6, GM-CSF and a moderate amount of IFN-gamma. Because of its properties (Th2-type lymphocytes with innate like characteristics), these FALC cells were termed as "natural helper cells" by the authors.</span><br />
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<span style="font-family: 'Trebuchet MS', sans-serif;"><u>B cells</u></span><br />
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<span style="font-family: 'Trebuchet MS', sans-serif;">B1 cells, as has been mentioned, provides a first-line defense against bacterial and some viral infections. They have a less-diverse antibody repertoire, but respond to pathogen-associated molecules more rapidly than B2 cells. B1 cells have been related to some metabolic diseases, due to the fact that they are responsive to LPS and cytokines (<a href="http://www.ncbi.nlm.nih.gov/pubmed/17060475">5</a>). Importantly, these cells also produce IL-10 (<a href="http://www.ncbi.nlm.nih.gov/pubmed/1547817">6</a>), which can regulate the activity of regulatory B cells (Bregs) (<a href="http://www.ncbi.nlm.nih.gov/pubmed/19758160">7</a>). The implications of obesity in the function of B1 cells has yet to be discovered, but given that endotoxemia (<a href="http://www.ncbi.nlm.nih.gov/pubmed/17456850">8</a>) and increased pro-inflammatory cytokine secretion are associated with obesity, overactivation of B1 cells could lead to the production of autoantibodies, promoting autoimmunity (<a href="http://www.ncbi.nlm.nih.gov/pubmed/8006578">9</a>). Autoantibody production by B1 cells can also be promoted by endocrine disruptors (<a href="http://www.ncbi.nlm.nih.gov/pubmed/15166399">10</a>). Finally, in contrast to their interaction with Bregs, B1 cells are unable to promote the conversion of naive Foxp3-CD4+ T cells into Foxp3+Treg cells (T-regulatory cells) compared to B2 cells, and promote Th1 and Th17 cell differentiation (see below) (<a href="http://www.ncbi.nlm.nih.gov/pubmed/17683116">11</a>). </span><br />
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<span style="font-family: 'Trebuchet MS', sans-serif;">The role of B2 cells in the pathogenesis of obesity has not been studied much, although there is an increase in total B cell count in adipose tissue from mice fed a high fat diet (HFD) (<a href="http://www.ncbi.nlm.nih.gov/pubmed/21499269">12</a>). B cells might have a role mediating glucose intolerance in the obese, probably through IgG (<a href="http://www.ncbi.nlm.nih.gov/pubmed/21499269">12</a>). Of note, some authors have suggested that B2 cells are atherogenic, while B1 cells are atheroprotective because BAFF-R deficient ApoE -/- mice (which are B2 depleted) show reduced inflammation and atherosclerosis (<a href="http://www.ncbi.nlm.nih.gov/pubmed/22238605">13</a>, <a href="http://www.ncbi.nlm.nih.gov/pubmed/21868694">14</a>). </span><br />
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<span style="font-family: 'Trebuchet MS', sans-serif;"><u>T-cells</u></span><br />
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<span style="font-family: 'Trebuchet MS', sans-serif;">Infiltration of T lymphocytes to adipose tissue occurs rapidly in mice fed a HFD and correlates with the impairment in insulin sensitivity and glucose metabolism (<a href="http://www.ncbi.nlm.nih.gov/pubmed/18420999">15</a>). Inducing obesity in mice produces an increase in CD8+ T cell levels in adipose tissue (epididymal fat), concomitantly with a reduction in CD4+ and Treg levels; accumulation which precedes macrophage infiltration (<a href="http://www.ncbi.nlm.nih.gov/pubmed/19633658">16</a>). Furthermore, <i>in vitro</i> experiments have demonstrated that obese epididymal fat induces T cell proliferation and co-culturing obese adipose tissue with CD8+ T cells and monocytes induces the differentiation of macrophages to an inflammatory phenotype </span><span style="font-family: 'Trebuchet MS', sans-serif;">(</span><a href="http://www.ncbi.nlm.nih.gov/pubmed/19633658" style="font-family: 'Trebuchet MS', sans-serif;">16</a><span style="font-family: 'Trebuchet MS', sans-serif;">). Wu, et al. (<a href="http://www.ncbi.nlm.nih.gov/pubmed/17296858">17</a>) found that obesity increases the level of regulated on activation, normal T cell expressed and secreted (RANTES) and CCR5 (one of RANTES receptors) in adipose tissue. This increases the migration of T-cells, as RANTES is chemotactic for these cells. The number of adipose tissue lymphocytes, </span><span style="font-family: 'Trebuchet MS', sans-serif;">as well as the expression of </span><a href="http://en.wikipedia.org/wiki/CCL20" style="font-family: 'Trebuchet MS', sans-serif;">CCL20</a>,<span style="font-family: 'Trebuchet MS', sans-serif;"> increases with the degree of adiposity (<a href="http://www.ncbi.nlm.nih.gov/pubmed/19644053">18</a>). Demonstrating a tight relationship between inflammation in adipose tissue and metabolic dysregulation, conditioned media from human adipose tissue lymphocytes is able to inhibit insulin-mediated FAS and LPL upregulation in mature adipocytes and to downregulate PIK3R1, effects probably mediated by IFN-gamma </span><span style="font-family: 'Trebuchet MS', sans-serif;">(</span><a href="http://www.ncbi.nlm.nih.gov/pubmed/19644053" style="font-family: 'Trebuchet MS', sans-serif;">18</a><span style="font-family: 'Trebuchet MS', sans-serif;">). In an elegant study, Winer, et al. (<a href="http://www.ncbi.nlm.nih.gov/pubmed/19633657/">19</a>) found that inducing obesity in mice produced the following changes in T-cell subsets in adipose tissue:</span><br />
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<li><span style="font-family: 'Trebuchet MS', sans-serif;">IFN-gamma secreting Th1 lymphocytes were higher in visceral adipose tissue (VAT) compared to subcutaneous adipose tissue (SAT).</span></li>
<li><span style="font-family: 'Trebuchet MS', sans-serif;">The proportion of CD4+Foxp3+ T cells (Tregs) was 70% lower in VAT from obese mice, which produced an increase in the Th1:Treg ratio from 1.5:1 in lean mice to 6.5:1. </span></li>
<li><span style="font-family: 'Trebuchet MS', sans-serif;">In absolute numbers, almost three times more Th1 cells accumulated per gram of fat in obese mice.</span></li>
<li><span style="font-family: 'Trebuchet MS', sans-serif;">In VAT from obese humans, the ratio of Th1:Treg was 12:1, compared to 6:1 in lean subjects. </span></li>
<li><span style="font-family: 'Trebuchet MS', sans-serif;">T-cell expansion in VAT seems to be antigen-driven, given that OVA-specific T cells in OT2 TCR transgenic mice (<a href="http://www.ncbi.nlm.nih.gov/pubmed/9553774">20</a>) showed secondary TCR-alpha rearrangements (thus, suggesting a positive selection towards an antigen present in VAT). These T-cells undergoing secondary TCR-alpha rearrangements in VAT showed a very narrow TCR-alpha diversity, implying a strong positive selection. Moreover, a negative pressure against selection of most of systemic TCR V-alpha (variable region in the alpha chain) was seen, given to the loss of some of these receptors**. </span></li>
<li><span style="font-family: 'Trebuchet MS', sans-serif;">To characterize the role of T-cells in obesity, the authors used Rag1-null mice, which lack lymphocytes. These mice, when fed a HFD, gain more weight and visceral fat than HFD fed wild type mice. These mice also developed glucose intolerance, showing hyperglycemia, hyperinsulinemia and low insulin sensitivity. These mice also displayed a significant elevation of blood glucose when fed a normal diet, suggesting a physiological role of lymphocytes on metabolism.</span></li>
<li><span style="font-family: 'Trebuchet MS', sans-serif;">Reconstitution of these mice with CD4+ (but not CD8+) improved the metabolic abnormalities. It also induced Treg repopulation in VAT, albeit slowly. The effect of CD4+ cells was not mediated through differentiation into Tregs, nor by increasing IL-10 levels but by differentiation into Th2 cells. </span></li>
<li><span style="font-family: 'Trebuchet MS', sans-serif;">Antibody treatment with anti-CD3 or <a href="http://en.wikipedia.org/wiki/Fragment_antigen-binding">F(ab')2</a> increased Treg levels in VAT and improved metabolic abnormalities. Additionally, F(ab')2 treatment increased the numbers of macrophage mannose receptor (MMR) positive cells (alternatively activated macrophages), increasing to almost 300% the production of IL-10.</span></li>
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<span style="font-family: 'Trebuchet MS', sans-serif;">The role of other inflammatory type of T-cell, Th17 cells, has been associated with obesity and metabolic complications. Diet-induced obese mice show an increased proliferation and differentiation towards Th17 cells, via an IL-6 dependent pathway (<a href="http://www.ncbi.nlm.nih.gov/pubmed/19662632">21</a>). This increase in Th17 potentiated the severity of <a href="http://en.wikipedia.org/wiki/Experimental_autoimmune_encephalomyelitis">EAE</a> and experimental colitis, reflecting the relationship between obesity and autoimmune risk. </span></div>
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<span style="font-family: 'Trebuchet MS', sans-serif;"><u>T-regulatory cells (Treg)</u></span><br />
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<span style="font-family: 'Trebuchet MS', sans-serif;">Treg cells have gotten much attention because they can regulate almost all immune responses. Further from being equal, different Treg populations display gene-expression differences (<a href="http://www.ncbi.nlm.nih.gov/pubmed/19536194">22</a>), and subphenotype differences in Treg cells from different organs suggest that these tissue-specific Tregs modulate the immune response in a given organ. Of relevance to the topic, adipose-tissue-resident Tregs have been characterized (<a href="http://www.ncbi.nlm.nih.gov/pubmed/19633656">23</a>). These fat Tregs had a different pattern of gene expression than their counterparts from other lymphoid organs: they over-represented genes coding for molecules involved in leukocyte migration and extravasation (CCR1, CCR2, CCR9, CXCL10, etc) and under-represented CCL5 and CXCR3. Fat Treg cells also seem to produce (and respond to, judging by expression of genes downstream of the IL-10 receptor) large amounts of IL-10, 136-fold higher than lymph node Tregs. The TCR repertoire of fat Treg cells was markedly different than that of adipose tissue T-cells and from other organs, suggesting that it is unlikely that these cells were the result of conversion of local T-cells. Finally, inducing T-cell conversion into Treg cells seem to ameliorate some metabolic abnormalities in rodent models </span><span style="font-family: 'Trebuchet MS', sans-serif;">(</span><a href="http://www.ncbi.nlm.nih.gov/pubmed/19633656" style="font-family: 'Trebuchet MS', sans-serif;">23</a><span style="font-family: 'Trebuchet MS', sans-serif;">). </span><br />
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<tr><td style="text-align: center;"><a href="http://3.bp.blogspot.com/-ouZRsiLQ-rQ/T0Rg78AdmMI/AAAAAAAAAEI/3ZhUFseAFoI/s1600/adipose+tissue+inflammation.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="400" src="http://3.bp.blogspot.com/-ouZRsiLQ-rQ/T0Rg78AdmMI/AAAAAAAAAEI/3ZhUFseAFoI/s400/adipose+tissue+inflammation.png" width="268" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: left;"><b style="text-align: justify;">Adipose tissue effects on adaptive immune cells.</b><span style="text-align: justify;"> Increases in adipose tissue mass promotes changes in adaptive immune cell subtypes, such as T and B cells. The production of pro-inflammatory and chemotactic molecules (RANTES, IL-6, TNF-alpha, IFN-gamma, CCR1, CCR2, etc.) induces Th1 and Th17 cell polarization, as well as secretion of IgG by B-cells. </span></td></tr>
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<span style="font-family: 'Trebuchet MS', sans-serif;"><u><b>Metabolic and immune integration</b></u></span><br />
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<span style="font-family: 'Trebuchet MS', sans-serif;">The function, differentiation and proliferation of several immune cell types is influenced by molecules that also play a key role in regulating metabolic homeostasis. Undoubtedly, leptin has gotten the most interest in recent years. Leptin is a master modulator of T-cell functioning: it promotes proliferation of peripheral blood lymphocytes and CD4+ T cells and induces the secretion of Th1 cytokines, such as IFN-gamma, while supressing the production of Th2 cytokines (<a href="http://www.ncbi.nlm.nih.gov/pubmed/9732873">24</a>, <a href="http://www.ncbi.nlm.nih.gov/pubmed/10675271">25</a>). Leptin also modulates apoptosis of Th1 cells, promoting their survival and it is necessary for a Th2 response <i>in vivo</i> (<a href="http://www.ncbi.nlm.nih.gov/pubmed/19966187">26</a>, <a href="http://www.ncbi.nlm.nih.gov/pubmed/11982586/">27</a>). How does leptin modulates polarization and proliferation of lymphocytes? Compared to wild type mice and reconstituted <i>ob/ob</i> mice, autoreactive CD4+ T-cells from leptin-deficient mice have lower levels of <a href="http://en.wikipedia.org/wiki/Bcl-2">Bcl-2</a> and phospho-ERK1/2, correlated with a reduction in the degradation of <a href="http://www.phosphosite.org/proteinAction.do?id=1021">p27Kip1</a>, a cell cycle inhibitor (<a href="http://www.ncbi.nlm.nih.gov/pubmed/21078910">28</a>). Treatment with rapamycin mimics the effects of leptin deficiency </span><span style="font-family: 'Trebuchet MS', sans-serif;">(</span><a href="http://www.ncbi.nlm.nih.gov/pubmed/21078910" style="font-family: 'Trebuchet MS', sans-serif;">28</a><span style="font-family: 'Trebuchet MS', sans-serif;">), suggesting that leptin acts through the mTOR pathway. The effects of leptin in cells from the innate and adaptive immune system are shown in the following table (adapted from <a href="http://www.ncbi.nlm.nih.gov/pubmed/22040697">Procaccini, et al., 2012</a>):</span><br />
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<b><span style="color: white; font-family: 'Trebuchet MS', sans-serif;">Cell type<o:p></o:p></span></b></div>
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<b><span style="color: white; font-family: 'Trebuchet MS', sans-serif;">Effect<o:p></o:p></span></b></div>
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<tr>
<td style="border-bottom: solid #4BACC6 1.0pt; border-left: solid #4BACC6 1.0pt; border-right: solid #548DD4 1.0pt; border-top: none; mso-border-alt: solid #4BACC6 1.0pt; mso-border-bottom-themecolor: accent5; mso-border-left-themecolor: accent5; mso-border-right-alt: solid #548DD4 .5pt; mso-border-right-themecolor: text2; mso-border-right-themecolor: text2; mso-border-right-themetint: 153; mso-border-right-themetint: 153; mso-border-themecolor: accent5; mso-border-top-alt: solid #4BACC6 1.0pt; mso-border-top-themecolor: accent5; padding: 0cm 5.4pt 0cm 5.4pt;" valign="top"><div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<b><span style="font-family: 'Trebuchet MS', sans-serif;">Monocytes/macrophages<o:p></o:p></span></b></div>
</td>
<td style="border-bottom: solid #4BACC6 1.0pt; border-left: none; border-right: solid #4BACC6 1.0pt; border-top: none; mso-border-bottom-themecolor: accent5; mso-border-left-alt: solid #548DD4 .5pt; mso-border-left-themecolor: text2; mso-border-left-themetint: 153; mso-border-right-themecolor: accent5; mso-border-top-alt: solid #4BACC6 1.0pt; mso-border-top-themecolor: accent5; padding: 0cm 5.4pt 0cm 5.4pt;" valign="top"><div class="MsoNormal" style="margin-bottom: 0.0001pt;">
↑<span style="font-family: 'Trebuchet MS', sans-serif;">Phagocytosis<o:p></o:p></span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
↑<span style="font-family: 'Trebuchet MS', sans-serif;">TNF-</span><span style="font-family: 'Trebuchet MS', sans-serif;">α</span><span style="font-family: 'Trebuchet MS', sans-serif;">, IL-6, IL-12<o:p></o:p></span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
↑<span style="font-family: 'Trebuchet MS', sans-serif;">Activation
markers<o:p></o:p></span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
↑<span style="font-family: 'Trebuchet MS', sans-serif;">Chemotaxis</span><span style="font-family: 'Trebuchet MS', sans-serif;"><o:p></o:p></span></div>
</td>
</tr>
<tr>
<td style="border-top: none; border: solid #548DD4 1.0pt; mso-border-alt: solid #548DD4 .5pt; mso-border-themecolor: text2; mso-border-themecolor: text2; mso-border-themetint: 153; mso-border-themetint: 153; mso-border-top-alt: solid #548DD4 .5pt; mso-border-top-themecolor: text2; mso-border-top-themetint: 153; padding: 0cm 5.4pt 0cm 5.4pt;" valign="top"><div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<b><span style="font-family: 'Trebuchet MS', sans-serif;">Dendritic
cells (DC)<o:p></o:p></span></b></div>
</td>
<td style="border-bottom: solid #548DD4 1.0pt; border-left: none; border-right: solid #548DD4 1.0pt; border-top: none; mso-border-alt: solid #548DD4 .5pt; mso-border-bottom-themecolor: text2; mso-border-bottom-themetint: 153; mso-border-left-alt: solid #548DD4 .5pt; mso-border-left-themecolor: text2; mso-border-left-themetint: 153; mso-border-right-themecolor: text2; mso-border-right-themetint: 153; mso-border-themecolor: text2; mso-border-themetint: 153; mso-border-top-alt: solid #548DD4 .5pt; mso-border-top-themecolor: text2; mso-border-top-themetint: 153; padding: 0cm 5.4pt 0cm 5.4pt;" valign="top"><div class="MsoNormal" style="margin-bottom: 0.0001pt;">
↑<span style="font-family: 'Trebuchet MS', sans-serif;">TGF</span><span style="font-family: 'Trebuchet MS', sans-serif;">β</span><span style="font-family: 'Trebuchet MS', sans-serif;"><o:p></o:p></span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
↑<span style="font-family: 'Trebuchet MS', sans-serif;">Th1 priming<o:p></o:p></span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
↑<span style="font-family: 'Trebuchet MS', sans-serif;">Survival<o:p></o:p></span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
↑<span style="font-family: 'Trebuchet MS', sans-serif;">Immature DC migration<o:p></o:p></span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
↑<span style="font-family: 'Trebuchet MS', sans-serif;">Stimulation of allogenic T
cells<o:p></o:p></span></div>
</td>
</tr>
<tr>
<td style="border-bottom: solid #4BACC6 1.0pt; border-left: solid #4BACC6 1.0pt; border-right: solid #548DD4 1.0pt; border-top: none; mso-border-alt: solid #4BACC6 1.0pt; mso-border-bottom-themecolor: accent5; mso-border-left-themecolor: accent5; mso-border-right-alt: solid #548DD4 .5pt; mso-border-right-themecolor: text2; mso-border-right-themecolor: text2; mso-border-right-themetint: 153; mso-border-right-themetint: 153; mso-border-themecolor: accent5; mso-border-top-alt: solid #4BACC6 1.0pt; mso-border-top-themecolor: accent5; padding: 0cm 5.4pt 0cm 5.4pt;" valign="top"><div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<b><span style="font-family: 'Trebuchet MS', sans-serif;">Neutrophils<o:p></o:p></span></b></div>
</td>
<td style="border-bottom: solid #4BACC6 1.0pt; border-left: none; border-right: solid #4BACC6 1.0pt; border-top: none; mso-border-bottom-themecolor: accent5; mso-border-left-alt: solid #548DD4 .5pt; mso-border-left-themecolor: text2; mso-border-left-themetint: 153; mso-border-right-themecolor: accent5; mso-border-top-alt: solid #4BACC6 1.0pt; mso-border-top-themecolor: accent5; padding: 0cm 5.4pt 0cm 5.4pt;" valign="top"><div class="MsoNormal" style="margin-bottom: 0.0001pt;">
↑<span style="font-family: 'Trebuchet MS', sans-serif;">Chemotaxis<o:p></o:p></span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
↑<span style="font-family: 'Trebuchet MS', sans-serif;">ROS</span><span style="font-family: 'Trebuchet MS', sans-serif;"><o:p></o:p></span></div>
</td>
</tr>
<tr>
<td style="border-top: none; border: solid #548DD4 1.0pt; mso-border-alt: solid #548DD4 .5pt; mso-border-themecolor: text2; mso-border-themecolor: text2; mso-border-themetint: 153; mso-border-themetint: 153; mso-border-top-alt: solid #548DD4 .5pt; mso-border-top-themecolor: text2; mso-border-top-themetint: 153; padding: 0cm 5.4pt 0cm 5.4pt;" valign="top"><div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<b><span style="font-family: 'Trebuchet MS', sans-serif;">NK
cells<o:p></o:p></span></b></div>
</td>
<td style="border-bottom: solid #548DD4 1.0pt; border-left: none; border-right: solid #548DD4 1.0pt; border-top: none; mso-border-alt: solid #548DD4 .5pt; mso-border-bottom-themecolor: text2; mso-border-bottom-themetint: 153; mso-border-left-alt: solid #548DD4 .5pt; mso-border-left-themecolor: text2; mso-border-left-themetint: 153; mso-border-right-themecolor: text2; mso-border-right-themetint: 153; mso-border-themecolor: text2; mso-border-themetint: 153; mso-border-top-alt: solid #548DD4 .5pt; mso-border-top-themecolor: text2; mso-border-top-themetint: 153; padding: 0cm 5.4pt 0cm 5.4pt;" valign="top"><div class="MsoNormal" style="margin-bottom: 0.0001pt;">
↑<span style="font-family: 'Trebuchet MS', sans-serif;">Activation marker<o:p></o:p></span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
↑<span style="font-family: 'Trebuchet MS', sans-serif;">Cytotoxic activity<o:p></o:p></span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
↑<span style="font-family: 'Trebuchet MS', sans-serif;">Perforin production<o:p></o:p></span></div>
</td>
</tr>
<tr>
<td style="border-top: none; border: solid #548DD4 1.0pt; mso-border-alt: solid #548DD4 .5pt; mso-border-themecolor: text2; mso-border-themecolor: text2; mso-border-themetint: 153; mso-border-themetint: 153; mso-border-top-alt: solid #548DD4 .5pt; mso-border-top-themecolor: text2; mso-border-top-themetint: 153; padding: 0cm 5.4pt 0cm 5.4pt;" valign="top"><div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<b><span style="font-family: 'Trebuchet MS', sans-serif;">B
cells<o:p></o:p></span></b></div>
</td>
<td style="border-bottom: solid #548DD4 1.0pt; border-left: none; border-right: solid #548DD4 1.0pt; border-top: none; mso-border-alt: solid #548DD4 .5pt; mso-border-bottom-themecolor: text2; mso-border-bottom-themetint: 153; mso-border-left-alt: solid #548DD4 .5pt; mso-border-left-themecolor: text2; mso-border-left-themetint: 153; mso-border-right-themecolor: text2; mso-border-right-themetint: 153; mso-border-themecolor: text2; mso-border-themetint: 153; mso-border-top-alt: solid #548DD4 .5pt; mso-border-top-themecolor: text2; mso-border-top-themetint: 153; padding: 0cm 5.4pt 0cm 5.4pt;" valign="top"><div class="MsoNormal" style="margin-bottom: 0.0001pt;">
↑<span style="font-family: 'Trebuchet MS', sans-serif;">Lymphopoiesis
and maturation<o:p></o:p></span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
↑<span style="font-family: 'Trebuchet MS', sans-serif;">IL-6,
IL-10, TNF-</span><span style="font-family: 'Trebuchet MS', sans-serif;">α<o:p></o:p></span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
↑<span style="font-family: 'Trebuchet MS', sans-serif;">IgG2a</span><span style="font-family: 'Trebuchet MS', sans-serif;"><o:p></o:p></span></div>
</td>
</tr>
<tr>
<td style="border-top: none; border: solid #548DD4 1.0pt; mso-border-alt: solid #548DD4 .5pt; mso-border-themecolor: text2; mso-border-themecolor: text2; mso-border-themetint: 153; mso-border-themetint: 153; mso-border-top-alt: solid #548DD4 .5pt; mso-border-top-themecolor: text2; mso-border-top-themetint: 153; padding: 0cm 5.4pt 0cm 5.4pt;" valign="top"><div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<b><span style="font-family: 'Trebuchet MS', sans-serif;">T
cells<o:p></o:p></span></b></div>
</td>
<td style="border-bottom: solid #548DD4 1.0pt; border-left: none; border-right: solid #548DD4 1.0pt; border-top: none; mso-border-alt: solid #548DD4 .5pt; mso-border-bottom-themecolor: text2; mso-border-bottom-themetint: 153; mso-border-left-alt: solid #548DD4 .5pt; mso-border-left-themecolor: text2; mso-border-left-themetint: 153; mso-border-right-themecolor: text2; mso-border-right-themetint: 153; mso-border-themecolor: text2; mso-border-themetint: 153; mso-border-top-alt: solid #548DD4 .5pt; mso-border-top-themecolor: text2; mso-border-top-themetint: 153; padding: 0cm 5.4pt 0cm 5.4pt;" valign="top"><div class="MsoNormal" style="margin-bottom: 0.0001pt;">
↑<span style="font-family: 'Trebuchet MS', sans-serif;">Activation markers<o:p></o:p></span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
↑<span style="font-family: 'Trebuchet MS', sans-serif;">Proliferation<o:p></o:p></span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
↑<span style="font-family: 'Trebuchet MS', sans-serif;">Th1 response<o:p></o:p></span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
↑<span style="font-family: 'Trebuchet MS', sans-serif;">Adhesion molecules<o:p></o:p></span></div>
</td>
</tr>
<tr>
<td style="border-top: none; border: solid #548DD4 1.0pt; mso-border-alt: solid #548DD4 .5pt; mso-border-themecolor: text2; mso-border-themecolor: text2; mso-border-themetint: 153; mso-border-themetint: 153; mso-border-top-alt: solid #548DD4 .5pt; mso-border-top-themecolor: text2; mso-border-top-themetint: 153; padding: 0cm 5.4pt 0cm 5.4pt;" valign="top"><div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<b><span style="font-family: 'Trebuchet MS', sans-serif;">Treg<o:p></o:p></span></b></div>
</td>
<td style="border-bottom: solid #548DD4 1.0pt; border-left: none; border-right: solid #548DD4 1.0pt; border-top: none; mso-border-alt: solid #548DD4 .5pt; mso-border-bottom-themecolor: text2; mso-border-bottom-themetint: 153; mso-border-left-alt: solid #548DD4 .5pt; mso-border-left-themecolor: text2; mso-border-left-themetint: 153; mso-border-right-themecolor: text2; mso-border-right-themetint: 153; mso-border-themecolor: text2; mso-border-themetint: 153; mso-border-top-alt: solid #548DD4 .5pt; mso-border-top-themecolor: text2; mso-border-top-themetint: 153; padding: 0cm 5.4pt 0cm 5.4pt;" valign="top"><div class="MsoNormal" style="margin-bottom: 0.0001pt;">
↓<span style="font-family: 'Trebuchet MS', sans-serif;">Proliferation<o:p></o:p></span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
↓<span style="font-family: 'Trebuchet MS', sans-serif;">Activity<o:p></o:p></span></div>
</td>
</tr>
</tbody></table>
<br />
<u style="font-family: 'Trebuchet MS', sans-serif;">mTOR</u><br />
<div>
<span style="font-family: 'Trebuchet MS', sans-serif;"><br /></span></div>
<span style="font-family: 'Trebuchet MS', sans-serif;">The mTOR pathway plays a very important role regulating immune function. Because of its role as a cellular energy sensor, it integrates metabolism and immunity, and provides a link for regulation of both by different molecules, such as leptin. </span>
<br />
<div>
<span style="font-family: 'Trebuchet MS', sans-serif;"><br /></span></div>
<span style="font-family: 'Trebuchet MS', sans-serif;">Besides commonly known upstream activators of mTOR (for example, growth factors like insulin), immune-associated molecules are also able to induce mTOR activity. CD28, a T-cell costimulatory receptor, is a potent activator of mTOR through the activation of PI3K (<a href="http://www.ncbi.nlm.nih.gov/pubmed/16493028">29</a>). Cytokines, such as IL-2, IL-4, IL-12, leptin, IFN-gamma and IL-1 are also able to activate mTOR (<a href="http://www.ncbi.nlm.nih.gov/pubmed/22136167">30</a>). Conversely, <a href="http://en.wikipedia.org/wiki/PD-1">PD-1 ligand 1</a> inhibits mTOR activity (<a href="http://www.ncbi.nlm.nih.gov/pubmed/20008522">31</a>). Proteins normally thought to function only as metabolic sensors can also regulate mTOR activity, providing the first mechanism by which metabolism and immunity are related. For example, AMPK phoshporylates TSC, promoting the inhibition of mTOR (<a href="http://www.ncbi.nlm.nih.gov/pubmed/16818670">32</a>, <a href="http://www.ncbi.nlm.nih.gov/pubmed/16613876">33</a>). The importance of AMPK for regulating the immune response is highlighted by the findings that loss of AMPK aggraviates EAE in mice (<a href="http://www.ncbi.nlm.nih.gov/pubmed/19486896/">34</a>). Aminoacids are potent activators of mTOR (<a href="http://www.ncbi.nlm.nih.gov/pubmed/21284988">35</a>) and Treg induction from naïve T-cells is dependent on amino acid availability (<a href="http://www.ncbi.nlm.nih.gov/pubmed/19567830/">36</a>).</span><br />
<div>
<span style="font-family: 'Trebuchet MS', sans-serif;"><br /></span></div>
<span style="font-family: 'Trebuchet MS', sans-serif;"><u>mTOR controls T-cell activation and differentiation</u> </span><br />
<div>
<span style="font-family: 'Trebuchet MS', sans-serif;"><br /></span></div>
<span style="font-family: 'Trebuchet MS', sans-serif;">mTOR plays a very important role integrating environmental cues for T-cell differentiation and activation. For a T-cell to become activated, two signals must be present. Signal 1 involves the recognition of antigens by TCR. On the other hand, Signal 2 has been defined as an species-specific accesory signal delivered by the stimulatory cell to the T-cell (<a href="http://www.ncbi.nlm.nih.gov/pubmed/19604300">37</a>). This means that for full T-cell activation, the two signals must be present. Signal 2, far from implicating only one type of interaction, is the result of the integration of multiple signals, which seem to be under the control of mTOR. For example, in Th1 cells, activation of mTOR is necessary for full T-cell activation and anergy reversal </span><span style="font-family: 'Trebuchet MS', sans-serif;">(</span><a href="http://www.ncbi.nlm.nih.gov/pubmed/19604300" style="font-family: 'Trebuchet MS', sans-serif;">37</a><span style="font-family: 'Trebuchet MS', sans-serif;">). Supporting the model of mTOR as Signal 2, experiments done on CD4+ T cells show that depending on the microenvironment (levels of specific cytokines), mTOR is necessary to differentiate T-cells into different subsets. Delgoffe, et al. (<a href="http://www.ncbi.nlm.nih.gov/pubmed/19538929">38</a>) deleted mTOR specifically in T-cells. These mutant cells proliferated normally (albeit slower than wild type), but werent able to differentiate into Th1, Th2 or Th17 after skewing conditions. This correlated with decreased STAT activation (STAT4 for Th1, STAT6 for Th2, STAT3 for Th17) and lack of upregulation of T-bet, GATA-3 and ROR-gammat expression (specific transcription factors for Th1, Th2 and Th17 cells, respectively). Surprisingly, TCR engagement in the absence of mTOR induced the differentiation of Foxp3+ cells. </span><br />
<div>
<span style="font-family: 'Trebuchet MS', sans-serif;"><br /></span></div>
<span style="font-family: 'Trebuchet MS', sans-serif;">mTOR also influences the activation of CD8+ cells. These cells are maintained in a quiescent state by several transcription factors, such as ELF4 and KLF4. mTOR controls CD8+ cell activation by inhibiting the expression of these proteins, reversing the quiescent state (<a href="http://www.ncbi.nlm.nih.gov/pubmed/20802152">39</a>, <a href="http://www.ncbi.nlm.nih.gov/pubmed/20060330">40</a>). CD8+ cells lacking mTORC1 fail to become effector cells, and transition to memory cells seems to be also under control of mTOR </span><span style="font-family: 'Trebuchet MS', sans-serif;">(</span><a href="http://www.ncbi.nlm.nih.gov/pubmed/22136167" style="font-family: 'Trebuchet MS', sans-serif;">30</a><span style="font-family: 'Trebuchet MS', sans-serif;">). Besides controlling activation, the PI3K-mTOR axis regulates T-lymphocyte trafficking (<a href="http://www.ncbi.nlm.nih.gov/pubmed/18391955">41</a>). </span><br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://1.bp.blogspot.com/-tTVQf5qtTqI/T0RgD8T6zQI/AAAAAAAAAEA/zsCEcwcew_I/s1600/mTOR.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="340" src="http://1.bp.blogspot.com/-tTVQf5qtTqI/T0RgD8T6zQI/AAAAAAAAAEA/zsCEcwcew_I/s400/mTOR.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: justify;"><b>mTOR effects on T-cell subsets.</b> mTORC1 is activated by growth factors (insulin, IGF-1, EGF, etc.), aminoacids (BCAAs), co-stimulatory molecules (CD-28) and several cytokines. Upon activation, mTORC1 promotes Th1 differentiation of CD4+ T-cells by activating STAT4, which in turns promotes transcription of T-bet; and Th17 by activating STAT3, which increases the expression of ROR-gammat. This effect is mediated by inhibition of SOCS3. Additionally, mTORC1 leads to activation of CD8+ T-cells by inhibiting the expression of ELF4 and KLF4, which maintains CD8+T-cells in a quiescent state. Upstream activation of mTORC2 is poorly understood, but growth factors and, recently, ribosomes have shown to activate this complex. mTORC2 promotes CD4+T-cell differentiation into Th2 cells, by inhibiting SOCS5, enhancing STAT6 phosphorylation. This leads to increased expression of GATA-3 transcription factor. Activation of mTORC2 also inhibits FOXO proteins. Both complexes inhibit Foxp3, thereby reducing Treg differentiation.</td></tr>
</tbody></table>
<span style="font-family: 'Trebuchet MS', sans-serif;"><u>mTOR promotes survival and maturation of B-cells</u></span><br />
<div>
<span style="font-family: 'Trebuchet MS', sans-serif;"><br /></span></div>
<span style="font-family: 'Trebuchet MS', sans-serif;">The direct effect of mTOR signaling in B-cell function has not been addressed. However, conditional deletion of TSC1 (mTORC1 inhibitor) in murine B-cells caused an impairment on B-cell maturation and response to T-cell dependent and independent antigens (<a href="http://www.ncbi.nlm.nih.gov/pubmed/21674478">42</a>). Moreover, survival and proliferation of activated B-cells requires PI3K and mTOR activation (<a href="http://www.ncbi.nlm.nih.gov/pubmed/12794110">43</a>).</span><br />
<div>
<span style="font-family: 'Trebuchet MS', sans-serif;"><br /></span></div>
<span style="font-family: 'Trebuchet MS', sans-serif;"><u>mTOR controls dendritic cell (DC) activation/maturation</u></span><br />
<div>
<span style="font-family: 'Trebuchet MS', sans-serif;"><br /></span></div>
<span style="font-family: 'Trebuchet MS', sans-serif;">Treatment of DC with rapamycin (mTOR inhibitor) inhibits maturation by IL-4, GM-CSF and IL-1b </span><span style="font-family: 'Trebuchet MS', sans-serif;">(</span><a href="http://www.ncbi.nlm.nih.gov/pubmed/19604300" style="font-family: 'Trebuchet MS', sans-serif;">37</a><span style="font-family: 'Trebuchet MS', sans-serif;">). These DC are poor stimulators of T-cells but promote the induction of T-cell tolerance by Treg induction (<a href="http://www.ncbi.nlm.nih.gov/pubmed/15643982">44</a>, <a href="http://www.ncbi.nlm.nih.gov/pubmed/17513751">45</a>). Rapamycin also produces a decrease in the expression of receptors involved in antigen presentation and uptake (<a href="http://www.ncbi.nlm.nih.gov/pubmed/12544886">46</a>) and synthesis of some cytokines, like IL-18 (<a href="http://www.ncbi.nlm.nih.gov/pubmed/18662782">47</a>). In LPS-stimulated DC, rapamycin enhances IL-12 production and supresses IL-10 expression (<a href="http://www.ncbi.nlm.nih.gov/pubmed/18492954">48</a>). This suggests that mTOR TLR-induced activation promotes the secretion of IL-10 while inhibiting the production of IL-12. Finally, mTOR is critical for monocyte-derived DC survival and immunostimulatory potential (<a href="http://www.ncbi.nlm.nih.gov/pubmed/20805416">49</a>).</span><br />
<div>
<span style="font-family: 'Trebuchet MS', sans-serif;"><br /></span></div>
<span style="font-family: 'Trebuchet MS', sans-serif;"><u>mTOR effects on immune cells is related to their metabolism</u></span><br />
<div>
<span style="font-family: 'Trebuchet MS', sans-serif;"><br /></span></div>
<span style="font-family: 'Trebuchet MS', sans-serif;">Every cell needs ATP for performing their specific functions. Unlike most differentiated cells (which utilize the citric acid cycle and mitochondrial respiration in the presence of oxygen), lymphocytes show a similar metabolic phenotype as cancer cells: they utilize oxidative glycolysis (Warburg effect) </span><span style="font-family: 'Trebuchet MS', sans-serif;">(</span><a href="http://www.ncbi.nlm.nih.gov/pubmed/22136167" style="font-family: 'Trebuchet MS', sans-serif;">30</a><span style="font-family: 'Trebuchet MS', sans-serif;">)</span><span style="font-family: 'Trebuchet MS', sans-serif;">. In the resting state, lymphocytes are in a catabolic state, and molecules required for protein synthesis and energy are provided by autophagy. Upon activation, when energy requirements increase, there is an upregulation in protein, nucleotide and lipid biosynthesis. This anabolic switch is mediated by immunostimulatory molecules. For instance, CD28 activates PI3K, which activates Akt, which in turn promotes membrane translocation of glucose transporters (principally GLUT1 in lymphocytes). This results in increased glucose uptake and glycolysis, in excess of what is required for sustaining an adequate cellular level of ATP or macromolecular synthesis (<a href="http://www.ncbi.nlm.nih.gov/pubmed/12121659">50</a>, <a href="http://www.ncbi.nlm.nih.gov/pubmed/18354169/">51</a>). CTLA-4, an inhibitory receptor, inhibits CD28-induced upregulation of glucose metabolism </span><span style="font-family: 'Trebuchet MS', sans-serif;">(</span><a href="http://www.ncbi.nlm.nih.gov/pubmed/12121659" style="font-family: 'Trebuchet MS', sans-serif;">50</a><span style="font-family: 'Trebuchet MS', sans-serif;">).</span><span style="font-family: 'Trebuchet MS', sans-serif;"> Activation of T-cells also leads to an increase in other glucose utilization pathways, such as the pentose phosphate pathway, which provides substrates for nucleic acid synthesis and NADPH (</span><a href="http://www.ncbi.nlm.nih.gov/pubmed/15067038" style="font-family: 'Trebuchet MS', sans-serif;">52</a><span style="font-family: 'Trebuchet MS', sans-serif;">). </span><br />
<div>
<span style="font-family: 'Trebuchet MS', sans-serif;"><br /></span></div>
<span style="font-family: 'Trebuchet MS', sans-serif;">The importance of these metabolic changes on T-cell functioning is shown by experiments in which blocking the PI3K-Akt-mTOR pathway inhibit T-cell activation. AICAR, which activates AMPK (and thereby inhibiting mTORC1) inhibits IL-2 synthesis and promotes T-cell anergy (<a href="http://www.ncbi.nlm.nih.gov/pubmed/15910743">53</a>). NALA, a leucine antagonist, and 2-deoxyglucose inhibit IL-2 and IFN-gamma synthesis, as well as proliferation of Th1 cells (<a href="http://www.ncbi.nlm.nih.gov/pubmed/19841171">54</a>). This effect was observed even in the presence of co-stimulation. </span><br />
<div>
<span style="font-family: 'Trebuchet MS', sans-serif;"><br /></span></div>
<span style="font-family: 'Trebuchet MS', sans-serif;">Treg cells display a different metabolic phenotype than effector CD4+ T cells. Whereas the latter exhibit a glycolytic dependent metabolism and high surface expression of GLUT1, Treg cells are dependent on lipid metabolism (<a href="http://www.ncbi.nlm.nih.gov/pubmed/21317389">55</a>). Michalek et al. found that glucose deficiency inhibits Th17 polarization, without affecting Treg differentiation. Moreover, blocking <a href="http://en.wikipedia.org/wiki/Carnitine_palmitoyltransferase_I">CPT-I</a> supressed Treg generation and the addition of exogenous fatty acids (oleate/palmitate mixture) inhibited the production of Th1, Th2 and Th17 cytokines (specifically, Th1 differentiation was reduced) but enhanced Treg expression of Foxp3. Finally, rapamycin and metformin increased lipid oxidation in CD4+ cells and Treg generation, while decreasing GLUT1 expression in CD4+ T-cells in a murine model of allergic asthma. </span><br />
<div>
<span style="font-family: 'Trebuchet MS', sans-serif;"><br /></span></div>
<span style="font-family: 'Trebuchet MS', sans-serif;"><b><u>Summary</u></b></span>
<br />
<ul>
<li><span style="font-family: 'Trebuchet MS', sans-serif;">Obesity alterates the immune balance in all immune cell types, by increasing the secretion of several cytokines and chemotactic molecules. Specifically, obesity is associated with Th1 and Th17 skewing, CD8+ T-cell activation and proliferation and reduction in Treg cell numbers. It also promotes IgG production by B-cells, which seems to be important for the metabolic alterations observed. </span></li>
<li><span style="font-family: 'Trebuchet MS', sans-serif;">Leptin, the most famous adipocytokine, is central to the relationship between immunity and metabolism. </span></li>
<li><span style="font-family: 'Trebuchet MS', sans-serif;">Leptin effects are mediated by mTOR, which in turn, is the link between metabolism and immune function. mTOR is now being proposed as Signal 2, which is required for full T-cell activation.</span></li>
<li><span style="font-family: 'Trebuchet MS', sans-serif;">mTOR controls T-cell activation, proliferation and differentiation. Activation of mTOR promotes Th1, Th17 and Th2 differentiation of CD4+ T-cells and inhibits Treg generation. It also controls survival, activation and maturation of B-cells and dendritic cells. </span></li>
<li><span style="font-family: 'Trebuchet MS', sans-serif;">Lymphocytes display a glycolytic metabolism, oxidizing glucose preferentially via aerobic glycolysis. Upon activation, mTOR and Akt increase the surface expression of GLUT1 and several enzymes involved in glucose uptake and oxidation. Conversely, Treg cells display a lipolytic metabolism, which is essential for their proliferation, differentiation and activity. </span></li>
<li><span style="font-family: 'Trebuchet MS', sans-serif;">The function, differentiation and activity of the different subsets of lymphocytes is dependent on nutrient and energy availability. </span></li>
</ul>
<span style="font-family: 'Trebuchet MS', sans-serif;">The results discussed above provide the basis for the potential of nutrition as a therapeutic tool in inflammatory and autoimmune conditions. In the next posts, I will expose my nutritional recommendations for treating these disorders, offering an up-to-date and detailed science-based nutritional immunotherapy.</span><br />
<span style="font-family: 'Trebuchet MS', sans-serif;"><br /></span><br />
<span style="font-family: 'Trebuchet MS', sans-serif;">* For <a href="http://en.wikipedia.org/wiki/Flow_cytometry">flow cytometric analysis</a>, specific cell surface markers are used for identifying distinct cell populations. Usually, a cell positive for a given marker is denoted by the marker and a plus sign (+), and a negative cell is written as the marker and a negative sign (-). So, for example, these cells present in FALCs express c-Kit and Sca-1, but not Lin markers. </span><br />
<span style="font-family: 'Trebuchet MS', sans-serif;">** For understanding the importance of these results, I strongly suggest some basic reading on <a href="http://en.wikipedia.org/wiki/T-cell_receptor">TCR</a> and <a href="http://en.wikipedia.org/wiki/V(D)J_recombination">V(D)J recombination</a>. </span><br />
<div>
<span style="font-family: 'Trebuchet MS', sans-serif;"><br /></span></div>
<span style="font-family: 'Trebuchet MS', sans-serif;"><b>Addendum</b></span><br />
<div>
<span style="font-family: 'Trebuchet MS', sans-serif;"><br /></span></div>
<span style="font-family: 'Trebuchet MS', sans-serif;">In the <a href="http://www.lucastafur.com/2012/02/adipose-tissue-immunity-basics-1.html">first part</a> of these series, I ommitted the <a href="http://www.ncbi.nlm.nih.gov/pubmed/19633655/">evidence</a> linking mast cells in the development of obesity and diabetes. I find utterly surprising that common mast cell stabilizers are able to improve these conditions. </span><br />
<span style="font-family: 'Trebuchet MS', sans-serif;"><br /></span><br />
<span style="font-family: 'Trebuchet MS', sans-serif;"><br /></span></div>
<span style="float: left; padding-bottom: 5px; padding-left: 5px; padding-right: 5px; padding-top: 5px;"><a href="http://www.researchblogging.org/"><img alt="ResearchBlogging.org" src="http://www.researchblogging.org/public/citation_icons/rb2_large_gray.png" style="border: 0;" /></a></span><span class="Z3988" title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.jtitle=Annual+review+of+immunology&rft_id=info%3Apmid%2F22136167&rfr_id=info%3Asid%2Fresearchblogging.org&rft.atitle=Regulation+of+Immune+Responses+by+mTOR.&rft.issn=0732-0582&rft.date=2011&rft.volume=&rft.issue=&rft.spage=&rft.epage=&rft.artnum=&rft.au=Powell+JD&rft.au=Pollizzi+KN&rft.au=Heikamp+EB&rft.au=Horton+MR&rfe_dat=bpr3.included=1;bpr3.tags=Biology%2CNutrition%2C+Immunology%2C+Molecular+Biology">Powell JD, Pollizzi KN, Heikamp EB, & Horton MR (2011). Regulation of Immune Responses by mTOR. <span style="font-style: italic;">Annual review of immunology</span> PMID: <a href="http://www.ncbi.nlm.nih.gov/pubmed/22136167" rev="review">22136167</a></span>
<br />
<div>
<span style="font-family: 'Trebuchet MS', sans-serif;"><br /></span></div>
<span class="Z3988" title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.jtitle=Nature+medicine&rft_id=info%3Apmid%2F19633657&rfr_id=info%3Asid%2Fresearchblogging.org&rft.atitle=Normalization+of+obesity-associated+insulin+resistance+through+immunotherapy.&rft.issn=1078-8956&rft.date=2009&rft.volume=15&rft.issue=8&rft.spage=921&rft.epage=9&rft.artnum=&rft.au=Winer+S&rft.au=Chan+Y&rft.au=Paltser+G&rft.au=Truong+D&rft.au=Tsui+H&rft.au=Bahrami+J&rft.au=Dorfman+R&rft.au=Wang+Y&rft.au=Zielenski+J&rft.au=Mastronardi+F&rft.au=Maezawa+Y&rft.au=Drucker+DJ&rft.au=Engleman+E&rft.au=Winer+D&rft.au=Dosch+HM&rfe_dat=bpr3.included=1;bpr3.tags=Biology%2CNutrition%2C+Immunology%2C+Molecular+Biology">Winer S, Chan Y, Paltser G, Truong D, Tsui H, Bahrami J, Dorfman R, Wang Y, Zielenski J, Mastronardi F, Maezawa Y, Drucker DJ, Engleman E, Winer D, & Dosch HM (2009).</span><span class="Z3988" title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.jtitle=Nature+medicine&rft_id=info%3Apmid%2F19633657&rfr_id=info%3Asid%2Fresearchblogging.org&rft.atitle=Normalization+of+obesity-associated+insulin+resistance+through+immunotherapy.&rft.issn=1078-8956&rft.date=2009&rft.volume=15&rft.issue=8&rft.spage=921&rft.epage=9&rft.artnum=&rft.au=Winer+S&rft.au=Chan+Y&rft.au=Paltser+G&rft.au=Truong+D&rft.au=Tsui+H&rft.au=Bahrami+J&rft.au=Dorfman+R&rft.au=Wang+Y&rft.au=Zielenski+J&rft.au=Mastronardi+F&rft.au=Maezawa+Y&rft.au=Drucker+DJ&rft.au=Engleman+E&rft.au=Winer+D&rft.au=Dosch+HM&rfe_dat=bpr3.included=1;bpr3.tags=Biology%2CNutrition%2C+Immunology%2C+Molecular+Biology">Normalization of obesity-associated insulin resistance through immunotherapy. <span style="font-style: italic;">Nature medicine, 15</span> (8), 921-9 PMID: <a href="http://www.ncbi.nlm.nih.gov/pubmed/19633657" rev="review">19633657</a></span><br />
<br />
<span class="Z3988" title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.jtitle=Molecular+aspects+of+medicine&rft_id=info%3Apmid%2F22040697&rfr_id=info%3Asid%2Fresearchblogging.org&rft.atitle=Leptin+as+an+immunomodulator.&rft.issn=0098-2997&rft.date=2012&rft.volume=33&rft.issue=1&rft.spage=35&rft.epage=45&rft.artnum=&rft.au=Procaccini+C&rft.au=Jirillo+E&rft.au=Matarese+G&rfe_dat=bpr3.included=1;bpr3.tags=Biology%2CNutrition%2C+Immunology%2C+Molecular+Biology">Procaccini C, Jirillo E, & Matarese G (2012). Leptin as an immunomodulator. <span style="font-style: italic;">Molecular aspects of medicine, 33</span> (1), 35-45 PMID: <a href="http://www.ncbi.nlm.nih.gov/pubmed/22040697" rev="review">22040697</a></span>Anonymousnoreply@blogger.com3tag:blogger.com,1999:blog-4724838399830873886.post-56124536682923158242012-02-08T12:20:00.000-08:002017-03-13T06:07:40.208-07:00Ancestral Health Symposium 2012<div style="text-align: justify;">
<span style="font-family: 'Trebuchet MS', sans-serif;">I have been selected for giving a talk this August, in the <a href="http://ancestryfoundation.org/">Ancestral Health Symposium 2012</a>, held in Harvard Law School. My 20-minute talk will be about Immunometabolism, where I will cover some basics of the immune system, the relationship between metabolism and immunity at a molecular level and how a paleo-type diet, coupled with other approaches, can be a powerful tool for controlling and preventing inflammatory and autoimmune diseases. I will discuss the effects of specific nutrients and food components on immune cell functioning, as well as some dietary suggestions based on individual symptoms. </span><br />
<span style="font-family: 'Trebuchet MS', sans-serif;"><br /></span><br />
<span style="font-family: 'Trebuchet MS', sans-serif;">Given that Im a post-graduate student travelling from Peru and Im working full time on my thesis, I am looking for some financial help for travel expenses. Additionally, Im looking for some help finding places to stay for a reasonable price. </span><br />
<span style="font-family: 'Trebuchet MS', sans-serif;"><br /></span><br />
<span style="font-family: 'Trebuchet MS', sans-serif;">If you are interested and find my work helpful, please send me an email to <a href="mailto:lucas@lucastafur.com">lucas@lucastafur.com</a> for further information. Any help is greatly appreciated. </span><br />
<span style="font-family: 'Trebuchet MS', sans-serif;"><br /></span><br />
<span style="font-family: 'Trebuchet MS', sans-serif;">Alternatively, you can send any donation through PayPal, to lucas@lucastafur.com. I have eliminated the "Donate" button because PayPal charges a commission that is not charged if you send the money directly to my email from the PayPal website.</span></div>Anonymousnoreply@blogger.com6tag:blogger.com,1999:blog-4724838399830873886.post-45684109223553261112012-02-01T20:54:00.000-08:002017-03-13T06:07:40.200-07:00Adipose tissue & Immunity: The basics 1<div style="text-align: justify;">
<span style="font-family: 'Trebuchet MS', sans-serif;">Obesity has been, and its still seen, as primarily a metabolic disease. Obesity results from increased energy intake and decreased energy expenditure, that is, a positive energy balance for a prolonged time. By this logic, to cure obesity and associated diseases, one must restrict calories and/or do more exercise. While this approach works (calorie restriction being the key player), it does not solve the cause of obesity in the first place. This has been shown by numerous evidence that finds that even after weight loss, there is still some metabolic dysfunction in previously obese people. Some obese people can't fully recover. This underscores a common problem in modern health science: clinicians and health practitioners only focus on the proximate cause and not in the ultimate cause (for an interesting read on the subject, see <a href="http://blogs.scientificamerican.com/a-blog-around-the-clock/2011/12/15/the-new-meanings-of-how-and-why-in-biology/?WT.mc_id=SA_facebook">this article</a>). Moreover, obesity is just the tip of the iceberg. We have evolved mechanisms to prevent the development of a rather unadvantageous phenotype. Obesity occurs when these mechanisms start to fail, such as when pathological insulin resistance and leptin resistance develop. </span></div>
<div style="text-align: justify;">
<span style="font-family: 'Trebuchet MS', sans-serif;"><br /></span></div>
<div style="text-align: justify;">
<span style="font-family: 'Trebuchet MS', sans-serif;">The obvious cause of obesity is the storage of excess energy as fat tissue. In this manner, excess energy causes an increased fat mass and problems start to arise due to the accumulation of excess body fat. While this statement is true, there is recent evidence that suggests that energy excess has also peripheral effects in cells that were previously unrelated to obesity; in particular, immune cells. </span></div>
<div style="text-align: justify;">
<span style="font-family: 'Trebuchet MS', sans-serif;"><br /></span></div>
<div style="text-align: justify;">
<span style="font-family: 'Trebuchet MS', sans-serif;"><u><b>Immunometabolism</b></u></span></div>
<div style="text-align: justify;">
<span style="font-family: 'Trebuchet MS', sans-serif;"><u><br /></u></span></div>
<div style="text-align: justify;">
<span style="font-family: 'Trebuchet MS', sans-serif;">Immunometabolism refers to "the </span><span style="font-family: 'Trebuchet MS', sans-serif;">interplay between immunological and metabolic processes" (<a href="http://www.ncbi.nlm.nih.gov/pubmed/21469396">1</a>). Traditionally, the immune system and metabolic processes have been viewed as different, non-related systems. Now, research findings suggest that this is not the case, on the contrary, both are very related and understanding their interplay is essential for preventing and treating metabolic disorders.</span></div>
<div style="text-align: justify;">
<span style="font-family: 'Trebuchet MS', sans-serif;"><br /></span></div>
<div style="text-align: justify;">
<span style="font-family: 'Trebuchet MS', sans-serif;">The hypothesis that the immune system is involved in the pathogenesis of obesity started from the findings that targeting proteins which are part of inflammatory cellular pathways ameliorated or prevented the development of obesity and insulin resistance. For instance, Uysal, et al. (<a href="http://www.ncbi.nlm.nih.gov/pubmed/9335502">2</a>) showed that a null mutation of the TNF-alpha and its two receptor genes improved insulin sensitivity in diet-induced obesity and in <a href="http://en.wikipedia.org/wiki/Ob/ob_mouse">ob/ob mice</a>. This confirmed previous <i>in vitro </i>evidence linking TNF-alpha with insulin resistance in adipocytes (<a href="http://www.ncbi.nlm.nih.gov/pubmed/8995390">3</a>). Interest began to increase with the discovery and characterization of adipocytokines, as well as the finding that the adipose tissue secretes inflammatory cytokines. </span><span style="font-family: 'Trebuchet MS', sans-serif;">Adipocytokines are cytokines produced mainly (but not exclusively) in the adipose tissue, and include adiponectin, leptin, resistin and visfatin; being the first two the main adipocytokines produced. Other cytokines secreted by adipocytes are TNF-alpha, IL-6, IL-1 and CCL2; as well as other proteins, including PAI-1 and some </span><a href="http://en.wikipedia.org/wiki/Complement_system" style="font-family: 'Trebuchet MS', sans-serif;">complement factors</a><span style="font-family: 'Trebuchet MS', sans-serif;">. The table below shows some immune and metabolic effects of the main cytokines discovered, as well as their potential role on inflammation (modified from <a href="http://www.ncbi.nlm.nih.gov/pubmed/16998510">Tilg & Moschen</a>, 2006). </span></div>
<div style="text-align: justify;">
<span style="font-family: 'Trebuchet MS', sans-serif;"><br /></span></div>
<div style="text-align: justify;">
</div>
<table border="1" cellpadding="0" cellspacing="0" class="MsoTableGrid" style="border-collapse: collapse; border: none; mso-border-alt: solid windowtext .5pt; mso-padding-alt: 0cm 5.4pt 0cm 5.4pt; mso-yfti-tbllook: 1184;">
<tbody>
<tr>
<td style="background: #F2DBDB; border: solid windowtext 1.0pt; mso-background-themecolor: accent2; mso-background-themetint: 51; mso-border-alt: solid windowtext .5pt; padding: 0cm 5.4pt 0cm 5.4pt;" valign="top"><div align="center" class="MsoNormal" style="margin-bottom: 0.0001pt; text-align: center;">
<b><span lang="ES-MX" style="font-family: 'Trebuchet MS', sans-serif;">Adipocytokine<o:p></o:p></span></b></div>
</td>
<td style="background: #F2DBDB; border-left: none; border: solid windowtext 1.0pt; mso-background-themecolor: accent2; mso-background-themetint: 51; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; padding: 0cm 5.4pt 0cm 5.4pt;" valign="top"><div align="center" class="MsoNormal" style="margin-bottom: 0.0001pt; text-align: center;">
<b><span lang="ES-MX" style="font-family: 'Trebuchet MS', sans-serif;">Effect on
inflammation<o:p></o:p></span></b></div>
</td>
<td style="background: #F2DBDB; border-left: none; border: solid windowtext 1.0pt; mso-background-themecolor: accent2; mso-background-themetint: 51; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; padding: 0cm 5.4pt 0cm 5.4pt;" valign="top"><div align="center" class="MsoNormal" style="margin-bottom: 0.0001pt; text-align: center;">
<b><span lang="ES-MX" style="font-family: 'Trebuchet MS', sans-serif;">Levels in obesity<o:p></o:p></span></b></div>
</td>
<td style="background: #F2DBDB; border-left: none; border: solid windowtext 1.0pt; mso-background-themecolor: accent2; mso-background-themetint: 51; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; padding: 0cm 5.4pt 0cm 5.4pt;" valign="top"><div align="center" class="MsoNormal" style="margin-bottom: 0.0001pt; text-align: center;">
<b><span lang="ES-MX" style="font-family: 'Trebuchet MS', sans-serif;">Immunity<o:p></o:p></span></b></div>
</td>
<td style="background: #F2DBDB; border-left: none; border: solid windowtext 1.0pt; mso-background-themecolor: accent2; mso-background-themetint: 51; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; padding: 0cm 5.4pt 0cm 5.4pt;" valign="top"><div align="center" class="MsoNormal" style="margin-bottom: 0.0001pt; text-align: center;">
<b><span lang="ES-MX" style="font-family: 'Trebuchet MS', sans-serif;">Metabolism</span></b><span lang="ES-MX" style="font-family: 'Trebuchet MS', sans-serif;"><o:p></o:p></span></div>
</td>
</tr>
<tr>
<td style="background: #F2DBDB; border-top: none; border: solid windowtext 1.0pt; mso-background-themecolor: accent2; mso-background-themetint: 51; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0cm 5.4pt 0cm 5.4pt;" valign="top"><div align="center" class="MsoNormal" style="margin-bottom: 0.0001pt; text-align: center;">
<span lang="ES-MX" style="font-family: 'Trebuchet MS', sans-serif;"><b>Adiponectin</b><o:p></o:p></span></div>
</td>
<td style="background: #F2F2F2; border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; mso-background-themecolor: background1; mso-background-themeshade: 242; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0cm 5.4pt 0cm 5.4pt;" valign="top"><div align="center" class="MsoNormal" style="margin-bottom: 0.0001pt; text-align: center;">
<span lang="ES-MX" style="font-family: 'Trebuchet MS', sans-serif;">Anti-inflammatory<o:p></o:p></span></div>
</td>
<td style="background: #F2F2F2; border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; mso-background-themecolor: background1; mso-background-themeshade: 242; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0cm 5.4pt 0cm 5.4pt;" valign="top"><div align="center" class="MsoNormal" style="margin-bottom: 0.0001pt; text-align: center;">
<span lang="ES-MX" style="font-family: 'Trebuchet MS', sans-serif;">Decreased<o:p></o:p></span></div>
</td>
<td style="background: #F2F2F2; border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; mso-background-themecolor: background1; mso-background-themeshade: 242; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0cm 5.4pt 0cm 5.4pt;" valign="top"><div class="MsoNormal" style="margin-bottom: 0.0001pt;">
↓<span style="font-family: 'Trebuchet MS', sans-serif;">NFκB <o:p></o:p></span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
↓<span style="font-family: 'Trebuchet MS', sans-serif;">TNF</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
↓<span style="font-family: 'Trebuchet MS', sans-serif;">Phagocytic
activity (macrophages)<o:p></o:p></span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
↑<span style="font-family: 'Trebuchet MS', sans-serif;">IL-10<o:p></o:p></span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
↑<span style="font-family: 'Trebuchet MS', sans-serif;">IL-1RA<o:p></o:p></span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
↓<span style="font-family: 'Trebuchet MS', sans-serif;">IFN-γ<o:p></o:p></span></div>
</td>
<td style="background: #F2F2F2; border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; mso-background-themecolor: background1; mso-background-themeshade: 242; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0cm 5.4pt 0cm 5.4pt;" valign="top"><div class="MsoNormal" style="margin-bottom: 0.0001pt;">
↓<span style="font-family: 'Trebuchet MS', sans-serif;">Hyperglycemia<o:p></o:p></span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
↓<span style="font-family: 'Trebuchet MS', sans-serif;">FFA<o:p></o:p></span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
↑<span style="font-family: 'Trebuchet MS', sans-serif;">Insulin
sensitivity<o:p></o:p></span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
↑<span style="font-family: 'Trebuchet MS', sans-serif;">β-oxidation<o:p></o:p></span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
↓<span style="font-family: 'Trebuchet MS', sans-serif;">SREBP1c<o:p></o:p></span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
↑<span style="font-family: 'Trebuchet MS', sans-serif;">AMPK</span><span style="font-family: 'Trebuchet MS', sans-serif;"><o:p></o:p></span></div>
</td>
</tr>
<tr>
<td style="background: #F2DBDB; border-top: none; border: solid windowtext 1.0pt; mso-background-themecolor: accent2; mso-background-themetint: 51; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0cm 5.4pt 0cm 5.4pt;" valign="top"><div align="center" class="MsoNormal" style="margin-bottom: 0.0001pt; text-align: center;">
<span lang="ES-MX" style="font-family: 'Trebuchet MS', sans-serif;"><b>Leptin</b><o:p></o:p></span></div>
</td>
<td style="background: #F2F2F2; border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; mso-background-themecolor: background1; mso-background-themeshade: 242; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0cm 5.4pt 0cm 5.4pt;" valign="top"><div align="center" class="MsoNormal" style="margin-bottom: 0.0001pt; text-align: center;">
<span lang="ES-MX" style="font-family: 'Trebuchet MS', sans-serif;">Pro-inflammatory<o:p></o:p></span></div>
</td>
<td style="background: #F2F2F2; border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; mso-background-themecolor: background1; mso-background-themeshade: 242; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0cm 5.4pt 0cm 5.4pt;" valign="top"><div align="center" class="MsoNormal" style="margin-bottom: 0.0001pt; text-align: center;">
<span lang="ES-MX" style="font-family: 'Trebuchet MS', sans-serif;">Increased<o:p></o:p></span></div>
</td>
<td style="background: #F2F2F2; border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; mso-background-themecolor: background1; mso-background-themeshade: 242; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0cm 5.4pt 0cm 5.4pt;" valign="top"><div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span lang="ES-MX">↑</span><span lang="ES-MX" style="font-family: 'Trebuchet MS', sans-serif;">TNF<o:p></o:p></span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span lang="ES-MX">↑</span><span lang="ES-MX" style="font-family: 'Trebuchet MS', sans-serif;">IL-6<o:p></o:p></span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span lang="ES-MX">↑</span><span lang="ES-MX" style="font-family: 'Trebuchet MS', sans-serif;">IL-12<o:p></o:p></span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span lang="ES-MX">↑</span><span lang="ES-MX" style="font-family: 'Trebuchet MS', sans-serif;">CCL2<o:p></o:p></span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span lang="ES-MX">↑</span><span lang="ES-MX" style="font-family: 'Trebuchet MS', sans-serif;">Th1 (IL-2, IFN-</span><span style="font-family: 'Trebuchet MS', sans-serif;">γ</span><span lang="ES-MX" style="font-family: 'Trebuchet MS', sans-serif;">)<o:p></o:p></span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
↓<span style="font-family: 'Trebuchet MS', sans-serif;">Th2
(IL-4)<o:p></o:p></span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
↑<span style="font-family: 'Trebuchet MS', sans-serif;">ROS<o:p></o:p></span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
↑<span style="font-family: 'Trebuchet MS', sans-serif;">Chemotaxis<o:p></o:p></span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
↑<span style="font-family: 'Trebuchet MS', sans-serif;">NK-cell
function<o:p></o:p></span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
↑<span style="font-family: 'Trebuchet MS', sans-serif;">Lymphopoiesis<o:p></o:p></span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
↑<span style="font-family: 'Trebuchet MS', sans-serif;">Thymocyte
survival<o:p></o:p></span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
↑<span style="font-family: 'Trebuchet MS', sans-serif;">T-cell
proliferation</span></div>
</td>
<td style="background: #F2F2F2; border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; mso-background-themecolor: background1; mso-background-themeshade: 242; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0cm 5.4pt 0cm 5.4pt;" valign="top"><div class="MsoNormal" style="margin-bottom: 0.0001pt;">
↑<span style="font-family: 'Trebuchet MS', sans-serif;">Energy
expenditure<o:p></o:p></span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
↑<span style="font-family: 'Trebuchet MS', sans-serif;">Satiety<o:p></o:p></span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
↑<span style="font-family: 'Trebuchet MS', sans-serif;">Insulin
sensitivity<o:p></o:p></span></div>
</td>
</tr>
<tr>
<td style="background: #F2DBDB; border-top: none; border: solid windowtext 1.0pt; mso-background-themecolor: accent2; mso-background-themetint: 51; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0cm 5.4pt 0cm 5.4pt;" valign="top"><div align="center" class="MsoNormal" style="margin-bottom: 0.0001pt; text-align: center;">
<span lang="ES-MX" style="font-family: 'Trebuchet MS', sans-serif;"><b>Resistin</b><o:p></o:p></span></div>
</td>
<td style="background: #F2F2F2; border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; mso-background-themecolor: background1; mso-background-themeshade: 242; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0cm 5.4pt 0cm 5.4pt;" valign="top"><div align="center" class="MsoNormal" style="margin-bottom: 0.0001pt; text-align: center;">
<span lang="ES-MX" style="font-family: 'Trebuchet MS', sans-serif;">Pro-inflammatory<o:p></o:p></span></div>
</td>
<td style="background: #F2F2F2; border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; mso-background-themecolor: background1; mso-background-themeshade: 242; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0cm 5.4pt 0cm 5.4pt;" valign="top"><div align="center" class="MsoNormal" style="margin-bottom: 0.0001pt; text-align: center;">
<span lang="ES-MX" style="font-family: 'Trebuchet MS', sans-serif;">Increased<o:p></o:p></span></div>
</td>
<td style="background: #F2F2F2; border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; mso-background-themecolor: background1; mso-background-themeshade: 242; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0cm 5.4pt 0cm 5.4pt;" valign="top"><div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span lang="ES-MX">↑</span><span lang="ES-MX" style="font-family: 'Trebuchet MS', sans-serif;">NF</span><span style="font-family: 'Trebuchet MS', sans-serif;">κ</span><span lang="ES-MX" style="font-family: 'Trebuchet MS', sans-serif;">B</span><span lang="ES-MX"><o:p></o:p></span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span lang="ES-MX">↑</span><span lang="ES-MX" style="font-family: 'Trebuchet MS', sans-serif;">TNF<o:p></o:p></span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span lang="ES-MX">↑</span><span lang="ES-MX" style="font-family: 'Trebuchet MS', sans-serif;">IL-6<o:p></o:p></span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span lang="ES-MX">↑</span><span lang="ES-MX" style="font-family: 'Trebuchet MS', sans-serif;">IL-1<o:p></o:p></span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span lang="ES-MX">↑</span><span lang="ES-MX" style="font-family: 'Trebuchet MS', sans-serif;">IL-12<o:p></o:p></span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
↑<span style="font-family: 'Trebuchet MS', sans-serif;">CCL2<o:p></o:p></span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
↑<span style="font-family: 'Trebuchet MS', sans-serif;">VCAM1<o:p></o:p></span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
↑<span style="font-family: 'Trebuchet MS', sans-serif;">ICAM1</span></div>
</td>
<td style="background: #F2F2F2; border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; mso-background-themecolor: background1; mso-background-themeshade: 242; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0cm 5.4pt 0cm 5.4pt;" valign="top"><div class="MsoNormal" style="margin-bottom: 0.0001pt;">
↑<span style="font-family: 'Trebuchet MS', sans-serif;">Hepatic
insulin resistance<o:p></o:p></span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<br /></div>
</td>
</tr>
<tr>
<td style="background: #F2DBDB; border-top: none; border: solid windowtext 1.0pt; mso-background-themecolor: accent2; mso-background-themetint: 51; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0cm 5.4pt 0cm 5.4pt;" valign="top"><div align="center" class="MsoNormal" style="margin-bottom: 0.0001pt; text-align: center;">
<span lang="ES-MX" style="font-family: 'Trebuchet MS', sans-serif;"><b>Visfatin</b><o:p></o:p></span></div>
</td>
<td style="background: #F2F2F2; border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; mso-background-themecolor: background1; mso-background-themeshade: 242; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0cm 5.4pt 0cm 5.4pt;" valign="top"><div align="center" class="MsoNormal" style="margin-bottom: 0.0001pt; text-align: center;">
<span lang="ES-MX" style="font-family: 'Trebuchet MS', sans-serif;">Pro-inflammatory<o:p></o:p></span></div>
</td>
<td style="background: #F2F2F2; border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; mso-background-themecolor: background1; mso-background-themeshade: 242; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0cm 5.4pt 0cm 5.4pt;" valign="top"><div align="center" class="MsoNormal" style="margin-bottom: 0.0001pt; text-align: center;">
<span lang="ES-MX" style="font-family: 'Trebuchet MS', sans-serif;">Increased<o:p></o:p></span></div>
</td>
<td style="background: #F2F2F2; border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; mso-background-themecolor: background1; mso-background-themeshade: 242; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0cm 5.4pt 0cm 5.4pt;" valign="top"><div class="MsoNormal" style="margin-bottom: 0.0001pt;">
↑<span style="font-family: 'Trebuchet MS', sans-serif;">IL-6<o:p></o:p></span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
↑<span style="font-family: 'Trebuchet MS', sans-serif;">IL-8<o:p></o:p></span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
↑<span style="font-family: 'Trebuchet MS', sans-serif;">IL-1β<o:p></o:p></span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
↑<span style="font-family: 'Trebuchet MS', sans-serif;">TNF<o:p></o:p></span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
↑<span style="font-family: 'Trebuchet MS', sans-serif;">ICAM-1<o:p></o:p></span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
↑<span style="font-family: 'Trebuchet MS', sans-serif;">IL-10, IL-1Ra (high concentrations)</span><span style="font-family: 'Trebuchet MS', sans-serif;"><o:p></o:p></span></div>
</td>
<td style="background: #F2F2F2; border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; mso-background-themecolor: background1; mso-background-themeshade: 242; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0cm 5.4pt 0cm 5.4pt;" valign="top"><div class="MsoNormal" style="margin-bottom: 0.0001pt;">
↓<span style="font-family: 'Trebuchet MS', sans-serif;">Insulin
resistance<o:p></o:p></span></div>
</td>
</tr>
</tbody></table>
<br />
<div style="text-align: justify;">
<span style="font-family: 'Trebuchet MS', sans-serif;"><u><b>The adipose tissue as an immune organ</b></u></span><br />
<div style="text-align: justify;">
<span style="font-family: 'Trebuchet MS', sans-serif;"><br /></span></div>
<span style="font-family: 'Trebuchet MS', sans-serif;">Besides the role of pro-inflammatory cytokines produced by the adipose tissue, research has shown that obesity alters the function of several immune cells. </span><span style="font-family: 'Trebuchet MS', sans-serif;">In an elegant study, Caspar-Bauguil, et al. (<a href="http://www.ncbi.nlm.nih.gov/pubmed/15953605">4</a>) found that immune cells are present in adipose tissue from mice, but their characteristics are different from other tissues, sharing some common ancestral features with hepatic immune cells. Specifically, the adipose tissue (levels of specific cell populations varying in different anatomical sites) shows both innate and adaptive features, such as the presence of Natural Killer cells (NK), NKT cells and delta-gamma T cells for the former and the presence of lymph nodes, B-cells and alpha-beta T-cells for the latter. </span><span style="font-family: 'Trebuchet MS', sans-serif;">This led the authors to propose that the adipose tissue (specially the epididymal adipose tissue) is an ancestral immune organ, due to the fact that delta-gamma T cells are thought to represent an evolutionary and functional bridge between the innate and adaptive immune systems. In addition, inguinal fat contained more adaptive immune cells. Not surprisingly, inducing obesity produced some changes in immune cells: NK cells in epididymal fat were decreased, whereas delta-gamma T cells were increased in inguinal fat and lymph nodes. </span><br />
<div style="text-align: justify;">
<span style="font-family: 'Trebuchet MS', sans-serif;"><br /></span></div>
<span style="font-family: 'Trebuchet MS', sans-serif;">The adipose tissue has site-specific properties and adipocytes interact in a paracrine fashion with adjacent lymphoid cells. Adipocytes near a lymph node are called "perinodal", and show differences from adipocytes far from lymph nodes (<a href="http://www.ncbi.nlm.nih.gov/pubmed/15946832">5</a>, <a href="http://www.ncbi.nlm.nih.gov/pubmed/18275823">6</a>):</span><br />
<br />
<ul>
<li><span style="font-family: 'Trebuchet MS', sans-serif;">They are smaller and size increases in a gradient manner from the node.</span></li>
<li><span style="font-family: 'Trebuchet MS', sans-serif;">Lipids extracted from perinodal adipose tissue contain proportionately more PUFAs and less SFA than those further from nodes or nodeless depots, proportion which is not significantly affected by diet (perinodal adipose tissue still has more PUFAs than nodeless adipose tissue). </span></li>
<li><span style="font-family: 'Trebuchet MS', sans-serif;">Perinodal adipocytes influence the lipid composition of dendritic cells (and other lymphoid cells) found in lymph nodes, which suggests that perinodal adipocytes provide energy to immune cells for their activity.</span></li>
<li><span style="font-family: 'Trebuchet MS', sans-serif;">Following chronic immune stimulation, ratios of omega-6/omega-3 PUFA converge in perinodal adipocytes, probably for providing more substrates for ecosanoid and docosanoid synthesis. </span></li>
<li><span style="font-family: 'Trebuchet MS', sans-serif;">Perinodal adipocytes are very sensitive to cytokines and noradrenaline, compared to adipocytes from other sites. </span></li>
</ul>
<br />
<span style="font-family: 'Trebuchet MS', sans-serif;">Diet can influence the activity of perinodal adipocytes and associated immune cells. For example, Mattacks, et al. (<a href="http://www.ncbi.nlm.nih.gov/pubmed/12064347">7</a>) compared the effect of feeding beef suet (mostly saturated and monounsaturated fat), sunflower oil (mostly omega-6 PUFA) and fish oil (mostly omega-3 PUFA) on the response of mesenteric, omental, popliteal and perirenal adipocytes to experimentally-induced local inflammation in guinea pigs. They found that basal lipolysis from sunflower oil-fed pigs was higher and lipolysis from perinodal adipocytes after incubation with noradrenaline was increased, compared with the other groups. The same authors found that the addition of sunflower seed oil (20%) to chow increased the number of dendritic cells in all adipose tissue samples, after stimulation with LPS </span><span style="font-family: 'Trebuchet MS', sans-serif;">(</span><a href="http://www.ncbi.nlm.nih.gov/pubmed/15182392" style="font-family: 'Trebuchet MS', sans-serif;">8</a><span style="font-family: 'Trebuchet MS', sans-serif;">).</span><br />
<div style="text-align: justify;">
<span style="font-family: 'Trebuchet MS', sans-serif;"><br /></span></div>
<span style="font-family: 'Trebuchet MS', sans-serif;">Infiltration of immune cells to adipose tissue is now an accepted phenomenon during obesity. It seems that CD4+ T lymphocytes are recruited to adipose tissue first, coinciding with the appearance of glucose intolerance and reduced insulin sensitivity, while macrophages accumulate at late stages of obesity-induced insulin resistance (<a href="http://www.ncbi.nlm.nih.gov/pubmed/18420999">9</a>, </span><a href="http://www.ncbi.nlm.nih.gov/pubmed/19422792" style="font-family: 'Trebuchet MS', sans-serif;">10</a><span style="font-family: 'Trebuchet MS', sans-serif;">). Infiltration of B-cells occur rapidly in mice, before any significant change in body fat mass (</span><a href="http://www.ncbi.nlm.nih.gov/pubmed/19422792" style="font-family: 'Trebuchet MS', sans-serif;">10</a><span style="font-family: 'Trebuchet MS', sans-serif;">).</span><br />
<div style="text-align: justify;">
<span style="font-family: 'Trebuchet MS', sans-serif;"><br /></span></div>
<span style="font-family: 'Trebuchet MS', sans-serif;"><u><b>Innate immunity and adipose tissue</b></u></span><br />
<div style="text-align: justify;">
<span style="font-family: 'Trebuchet MS', sans-serif;"><br /></span></div>
<span style="font-family: 'Trebuchet MS', sans-serif;">As has been mentioned, some adipose tissue show the presence of innate immune cells. One striking fact is that adipocytes and macrophages show similar characteristics. Weisberg, et al. (<a href="http://www.ncbi.nlm.nih.gov/pubmed/14679176">11</a>) found that the expression of 1,304 transcripts in perigonadal adipose tissue from different mice correlated significantly with body mass. Of the 100 most significantly correlated genes, 30% encoded macrophage specific proteins. In mice, the adipose tissue is a major source of IL-6 during systemic inflammation produced by LPS (<a href="http://www.ncbi.nlm.nih.gov/pubmed/19377014">12</a>). The tight relationship between adipocytes and monocytes/macrophages is exemplified by <a href="http://en.wikipedia.org/wiki/C3a_(complement)">C3a</a>. After activation of the alternative complement pathway, C3a induces mast cell degranulation and an immune response. This protein is also produced by adipocytes and the N-terminal cleavage of its alpha chain through the interaction of complement factors B and adipsin, followed by C-terminal arginine cleavage by serum carboxipeptidase N produces acylation stimulating protein (ASP) or C3adesArg, which is an important regulator of triglyceride synthesis. Moreover, C3a (ASP precursor) can also have metabolic effects: its receptor, C3aR, is expressed on both monocytes-macrophages and adipocytes. C3aR null mice are transiently resistant to diet-induced obesity, and are protected from diet-induced insulin resistance and hepatic steatosis, showing improved insulin sensitivity compared to wild-type mice (<a href="http://www.ncbi.nlm.nih.gov/pubmed/19581423">13</a>). This was accompanied by a decrease in macrophage infiltration to adipose tissue, plasma cytokine levels and a polarization of macrophages towards a M1 phenotype (see below).</span><br />
<div style="text-align: justify;">
<span style="font-family: 'Trebuchet MS', sans-serif;"><br /></span></div>
<span style="font-family: 'Trebuchet MS', sans-serif;">Toll-like receptors (TLR) are pattern recognition molecules with an essential function recognizing pathogens via pathogen-associated molecular patterns (PAMPs). Several types of TLRs are expressed by pre- and mature murine adipocytes, but mature adipocytes seem to be more responsive to a broader spectrum of TRL ligands (<a href="http://www.ncbi.nlm.nih.gov/pubmed/17681884">14</a>). LPS triggers the secretion of IL-6 and different chemokines (CCL2, CCL5 and CCL11) and this inflammatory response appears to be based mainly on preadipocytes. The ultimate result of the activation of TLRs in adipocytes is the secretion of inflammatory cytokines via activation of NFkB signaling. Accordingly, LPS increases the expression of TLR2, TRAF-6 and NFkB in human adipose tissue, and increased levels of these markers, as well as LPS, is observed in type 2 diabetic patients (<a href="http://www.ncbi.nlm.nih.gov/pubmed/17090751">15</a>). The finding that mice with defects on different TLRs are protected from obesity and insulin resistance supports the role of TRLs in the development of metabolic dysregulation (<a href="http://www.ncbi.nlm.nih.gov/pubmed/18421279">16</a>, <a href="http://www.ncbi.nlm.nih.gov/pubmed/17519423">17</a>, <a href="http://www.ncbi.nlm.nih.gov/pubmed/20434320">18</a>, <a href="http://www.ncbi.nlm.nih.gov/pubmed/20407745">19</a>). Additionally, it suggests that different inflammatory stimuli act in the adipose tissue via different TLRs.</span><br />
<div style="text-align: justify;">
<span style="font-family: 'Trebuchet MS', sans-serif;"><br /></span></div>
<span style="font-family: 'Trebuchet MS', sans-serif;">Macrophages infiltrating the adipose tissue can have two potential sources: those differentiated from bone-marrow-derived monocytes which reach the adipose tissue from the systemic circulation or by trans-differentiation from local adipose tissue preadipocytes and mesenchymal stem cells (<a href="http://www.ncbi.nlm.nih.gov/pubmed/17681884">14</a>). Diapedesis of monocytes is stimulated by chemoattractants secreted by adipocytes (CCL2, CCL5, MIF and MIP1a) and locally produced macrophage colony stimulating factor (M-CSF) supports differentiation and maturation of monocytes into macrophages. On the other hand, both adipocyte and macrophage differentiation and function is controlled by PPAR-gamma. In addition, adipocytes also express macrophage-specific genes (<a href="http://www.ncbi.nlm.nih.gov/pubmed/14760416">20</a>). This suggests that both cell types arise from a common precursor cell, and trans-differentiation of adipocytes into macrophages is supported by the findings of Charriere, et al. (<a href="http://www.ncbi.nlm.nih.gov/pubmed/12519759">21</a>): preadipocytes are able to convert into macrophage-like cells, judging by specific antigens and the phagocytic index. Similar findings have been observed in other studies (<a href="http://www.ncbi.nlm.nih.gov/pubmed/9973318">22</a>, <a href="http://www.ncbi.nlm.nih.gov/pubmed/11571587">23</a>), which report that preadipocytes can phagocyte and kill micro-organisms. </span><br />
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<span style="font-family: 'Trebuchet MS', sans-serif;">Macrophages can show different activities depending on their phenotype. Classically activated macrophages (M1) respond to products derived from or associated with bacterial infections, like LPS and IFN-gamma. These macrophages are characterized by a highly inflammatory phenotype, displaying high phagocytic and bactericidal potential. Alternatively activated macrophages (M2) are induced in response to products from or associated with parasitic infections, such as <a href="http://www.lucastafur.com/2011/10/good-worms.html"><i>Schistosoma</i> egg antigen</a> and Th2-type cytokines like IL-4 and IL-13 </span><span style="font-family: 'Trebuchet MS', sans-serif;">(</span><a href="http://www.ncbi.nlm.nih.gov/pubmed/21034223" style="font-family: 'Trebuchet MS', sans-serif;">24</a><span style="font-family: 'Trebuchet MS', sans-serif;">). M2 stimulate tissue repair and remodeling. Contrary to what was thought, adipose tissue from lean animals does have macrophages. However, obesity, besides promoting infiltration and migration of macrophages, induces a shift in macrophage balance towards M1 phenotype (<a href="http://www.ncbi.nlm.nih.gov/pubmed/17200717">25</a>). In fact, obesity shifts the adipose M2:M1 ratio from 4:1 in normal mice to 1.2:1 (<a href="http://www.ncbi.nlm.nih.gov/pubmed/18829989">26</a>). Th2-type cytokines derived from the adipose tissue (IL-13 and IL-4) regulate macrophage polarization, favoring alternative activation (<a href="http://www.ncbi.nlm.nih.gov/pubmed/18522830">27</a>). M2 development is also promoted by IL-10 (<a href="http://www.ncbi.nlm.nih.gov/pubmed/19690061">28</a>). </span><br />
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<span style="font-family: 'Trebuchet MS', sans-serif;">The role of other innate cells is not well characterized. It has been seen that peripheral natural killer (NK) cell levels in unhealthy obese patients is reduced compared with healthy obese, and NK cells from these patients show increased levels of inhibitory markers (CD158b and NKB1), but expression of CD69, a marker of NK activation (<a href="http://www.ncbi.nlm.nih.gov/pubmed/19238145">29</a>). This suggests that although activated, NK cells from unhealthy obese patients cannot function properly. In visceral adipose tissue from obese subjects, there is an increase in NK cells compared to subcutaneous fat (<a href="http://www.ncbi.nlm.nih.gov/pubmed/19564875/">30</a>). Another type of innate cells, natural killer T (NKT) cells , which are T-like innate cells capable of producing both Th-1 and Th-2 type cytokines have been implicated in the inflammatory environment seen in obesity. Mice lacking NKT cells show reduced macrophage infiltration in response to a high-fat diet, and activation of NKT cells by alpha-galactosylceramide exacerbates glucose intolerance, macrophage infiltration and cytokine gene expression in diet-induced obese mice (<a href="http://www.ncbi.nlm.nih.gov/pubmed/19910631">31</a>). However, the effects of NKT cells on obesity and insulin resistance seem to be dependent on CD8+ T cells (<a href="http://www.ncbi.nlm.nih.gov/pubmed/21674035">32</a>). </span><br />
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<span style="font-family: 'Trebuchet MS', sans-serif;"><b><u>Summary</u></b></span><br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://4.bp.blogspot.com/-08sM8MM34YA/TyoR89hN5MI/AAAAAAAAAC8/uJIDhpUPpHA/s1600/innateadipose.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="265" src="http://4.bp.blogspot.com/-08sM8MM34YA/TyoR89hN5MI/AAAAAAAAAC8/uJIDhpUPpHA/s400/innateadipose.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><b>Interrelationship between the adipose tissue and the immune system. </b>The adipose tissue (AT) secretes adipocytokines (adiponectin, resistin, leptin, visfatin, among others) and conventional cytokines (TNF-a, IFN-gamma. IL-6, etc.), which influence metabolism and immunity. Cells from the innate and adaptive immune system are present in AT, and are fueled by perinodal adipocytes. Adipocytokines influence the function of immune cells, and cytokines secreted both by adipocytes and immune cells regulate the inflammatory milieu of the AT. Nutrition, by regulating fat mass and lipid composition, has direct effects on the function of immune cells.</td></tr>
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<span style="float: left; padding-bottom: 5px; padding-left: 5px; padding-right: 5px; padding-top: 5px;"><a href="http://www.researchblogging.org/"><img alt="ResearchBlogging.org" src="http://www.researchblogging.org/public/citation_icons/rb2_large_white.png" style="border: 0;" /></a></span><span style="font-family: 'Trebuchet MS', sans-serif;"><u><br /></u></span></div>
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<span class="Z3988" title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.jtitle=Trends+in+immunology&rft_id=info%3Apmid%2F20434953&rfr_id=info%3Asid%2Fresearchblogging.org&rft.atitle=Innate+immunity+and+adipose+tissue+biology.&rft.issn=1471-4906&rft.date=2010&rft.volume=31&rft.issue=6&rft.spage=228&rft.epage=35&rft.artnum=&rft.au=Sch%C3%A4ffler+A&rft.au=Sch%C3%B6lmerich+J&rfe_dat=bpr3.included=1;bpr3.tags=Biology%2CNutrition%2C+Immunology%2C+Molecular+Biology">Schäffler A, & Schölmerich J (2010). Innate immunity and adipose tissue biology. <span style="font-style: italic;">Trends in immunology, 31</span> (6), 228-35 PMID: <a href="http://www.ncbi.nlm.nih.gov/pubmed/20434953" rev="review">20434953</a></span> </div>
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<div style="text-align: justify;">
<span class="Z3988" title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.jtitle=Prostaglandins%2C+leukotrienes%2C+and+essential+fatty+acids&rft_id=info%3Apmid%2F15946832&rfr_id=info%3Asid%2Fresearchblogging.org&rft.atitle=Adipose+tissue+and+the+immune+system.&rft.issn=0952-3278&rft.date=2005&rft.volume=73&rft.issue=1&rft.spage=17&rft.epage=30&rft.artnum=&rft.au=Pond+CM&rfe_dat=bpr3.included=1;bpr3.tags=Biology%2CNutrition%2C+Immunology%2C+Molecular+Biology">Pond CM (2005). Adipose tissue and the immune system. <span style="font-style: italic;">Prostaglandins, leukotrienes, and essential fatty acids, 73</span> (1), 17-30 PMID: <a href="http://www.ncbi.nlm.nih.gov/pubmed/15946832" rev="review">15946832</a></span>
</div>Anonymousnoreply@blogger.com6tag:blogger.com,1999:blog-4724838399830873886.post-32373801460221297592012-01-12T12:08:00.000-08:002017-03-13T06:07:40.198-07:00Safe starches, blood glucose and insulin<div style="text-align: justify;">
<span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;">A reader asked me recently about a subject which is confusing many people in the paleosphere. </span></div>
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<span class="Apple-style-span" style="background-color: white;"><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"><span class="Apple-style-span">"</span><span class="Apple-style-span" style="color: #222222;"><span class="Apple-style-span">Jaminet in his debate with Rosedale suggests higher carb diets tend to lower blood sugar whereas low carb diets, RAISE it. Can you help me untangle what is going on here? It makes it sound like the more carbs you eat the better your blood sugar levels which does not seem right to me. Clearly, an important health goal is achieving low blood glucose so I would want to know what is the best way to eat to control them.</span></span></span> </span></blockquote>
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<span class="Apple-style-span" style="background-color: white;"><span class="Apple-style-span" style="color: #222222; font-family: 'Trebuchet MS', sans-serif;"><span class="Apple-style-span">I always assumed that the less sugar you eat, the less blood sugar you'll have. Is there a threshold? If Jaminet is correct, then shouldn't we see a higher fasting glucose associated with ketogenic diets that are totally carb restricted vs higher carb diets? I know excess protein might be converted into glucose but if you followed a ketogenic diet with low protein would you still see the rise in blood glucose?</span></span><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"> </span></span></blockquote>
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<span class="Apple-style-span" style="background-color: white; font-family: 'Trebuchet MS', sans-serif;"><span class="Apple-style-span" style="color: #222222;">What is the mechanism through which blood glucose is being lowered in high carbers? Do they secrete more insulin to deal with it hence lower blood glucose? Would their insulin levels therefore be higher even if blood glucose was relatively low? Which is worse for health- low glucose/high insulin or moderate glucose/low insulin?</span> </span></blockquote>
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<span class="Apple-style-span" style="color: #222222;"><span class="Apple-style-span" style="background-color: white; font-family: 'Trebuchet MS', sans-serif;">What is the mechanism through which some cancers are being suppressed with ketogenic diets if not through lowered blood glucose? Is there something else going on?"</span></span></blockquote>
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<span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;">These are very important questions as they raise some concern in people which utilize a low carbohydrate diet for controlling their blood glucose (BG). Before trying to elaborate an answer, there are some facts that must be kept in mind:</span></div>
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<li><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;">Hyperglycemia is not a disease, it is a symptom. </span></li>
<li><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;">BG levels can be affected by non-dietary factors.</span></li>
<li><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;">The two principal energy substrates for humans (glucose and free fatty acids (FFA)) compete with each other for their utilization.</span></li>
<li><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;">Calories matter.</span></li>
<li><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;">There are differences between physiological insulin resistance (PIR) and pathological insulin resistance (PaIR). The term "insulin resistance" is very vague, it doesn't define explicitly which tissue(s) is IR.</span></li>
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<span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;">The first issue to adress is whether ketogenic diets raise BG levels. The only evidence I have seen for this happening is in anecdotes from people in the internet. But if we want to have an objective look at the subect, we must see what happens in studies done with ketogenic diets (I will use low carbohydrate and ketogenic diets equally). </span></div>
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<u>Ketogenic diets and blood glucose levels</u></div>
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Most studies done on ketogenic diets are short-term and involve weight loss. All of them show a reduction in BG and insulin levels. A study by Grieb et al. (<a href="http://www.ncbi.nlm.nih.gov/pubmed/19083495">1</a>) found that people eating an optimal diet (Kwasniewski) had on average a BG level of 87.9mg/dL, which is in the normal range; and very low values of <a href="http://en.wikipedia.org/wiki/Homeostatic_model_assessment">HOMA-IR</a>. Sharman et al. (<a href="http://www.ncbi.nlm.nih.gov/pubmed/12097663">2</a>) have shown that the metabolic benefits of carbohydrate restriction are independent of weight loss. Given the evidence, it is only possible to speculate about the mechanisms by which BG levels rise in some people eating a ketogenic diet.</div>
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The goal of a ketogenic diet is to simulate fasting, but without the negative effects of prolonged nutrient restriction. Before going on, it is pertinent to remember the Randle Cycle (<a href="http://www.ncbi.nlm.nih.gov/pubmed/19531645">3</a>):</div>
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In short, both FFA and glucose compete with each other for their uptake and oxidation. This can be translated as when BG is high, FFA utilization is low; and when BG is low, FFA utilization is high. Ketogenic diets are characterized by low BG levels, in part because of a drastic reduction in exongeous glucose. In turn, plasma FFA rise from dietary and endogenous sources (the contribution of each one depends on energy balance). During this scenario, plasma ketone bodies also rise. So we have the following metabolic milieu:</div>
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<a href="http://3.bp.blogspot.com/-u51wLEmu51s/TuluBWW-pUI/AAAAAAAAACk/FN95sG018k0/s1600/KETOGENIC+DIET.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="320" src="http://3.bp.blogspot.com/-u51wLEmu51s/TuluBWW-pUI/AAAAAAAAACk/FN95sG018k0/s320/KETOGENIC+DIET.png" width="179" /></a></div>
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<u>Cellular effects of a fasting-type metabolism</u></div>
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For exerting it metabolic effects, insulin needs to first bind its receptor (the insulin receptor, IR). Upon binding, insulin triggers an intracellular signaling cascade, which influences both the function of intracellular proteins and gene expression. The signaling pathway triggered by the binding of insulin include the recruitment of the IRS (insulin receptor substrate) to the cytosolic part of the insulin receptor dimer. <b>The signaling cascade stimulated by insulin is essential for its function. </b>If proteins involved in this signaling pathway are inhibited, there will be no cellular response to the binding of insulin and the activation of IR.</div>
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One level of inhibition of glucose utilization by FFA involves the inhibition of GLUT4 translocation to the plasma membrane. The translocation of GLUT4 is stimulated by insulin, by activation of IRS, PI3K and other proteins (<a href="http://www.ncbi.nlm.nih.gov/pubmed/8396927">4</a>, <a href="http://www.ncbi.nlm.nih.gov/pubmed/16024515">5</a>). <i>In vitro</i> studies have shown that palmitate, the main fatty acid stored in mammalian adipose tissue, inhibits GLUT4 translocation and activity (<a href="http://www.ncbi.nlm.nih.gov/pubmed/20805226">6</a>, <a href="http://www.ncbi.nlm.nih.gov/pubmed/17550999">7</a>). This results in reduced glucose uptake in skeletal muscle.</div>
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Inactivation of PDH (pyruvate dehydrogenase) is one of the most important mechanisms for inhibition of glucose oxidation by FFA. PDH activity is controlled by phosphorylation, by PDK (pyruvate dehydrogenase kinase) and PDP (pyruvate dehydrogenase phosphatase). Phosphorylation by PDK inactivates PDH, while dephosphorylation by PDP activates it. Fatty acid oxidation increases the mitochondrial ratios of [acetyl-CoA]/[CoA] and [NADH]/[NAD+], which inhibit PDH. Low carbohydrate diets have shown to reduce muscle PDH and increase PDK (<a href="http://www.ncbi.nlm.nih.gov/pubmed/9843740">8</a>, <a href="http://www.ncbi.nlm.nih.gov/pubmed/11701428">9</a>), effects which are reversed by a carbohydrate refeeding (<a href="http://www.ncbi.nlm.nih.gov/pubmed/19625693">10</a>). Fatty acids also increase the concentration of cytosolic citrate, which inhibits 6-phosphofructo-1-kinase, providing another mechanism of inhibition of glucose oxidation (<a href="http://www.ncbi.nlm.nih.gov/pubmed/19531645">3</a>). Fatty acids can reduce phosphorylation of IRS-1 (<a href="http://www.ncbi.nlm.nih.gov/pubmed/16150913">11</a>), GSK-3b and PKB/Akt (<a href="http://www.ncbi.nlm.nih.gov/pubmed/18434357">12</a>), thereby acting also downstream of IR and IRS.</div>
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The metabolic response to fasting can show what are the effects on insulin signaling of very high levels of plasma FFA and ketone bodies, but within a physiological range. In a very interesting study, Soeters et al (<a href="http://www.ncbi.nlm.nih.gov/pubmed/18397976">13</a>) found that insulin-mediated peripheral glucose uptake after 62h of fasting was significantly lower compared to 14h of fasting. They also found that after 62h of fasting, Akt phosphorylation at Ser473 and AS160 phosphorylation at Thr642 were reduced. This implies that insulin signaling was attenuated (reduced phosphorylation of Akt) as well as glucose uptake (phosphorylation of AS160 is involved in the translocation of GLUT4). The authors concluded:</div>
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<span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;">"(...) <span class="Apple-style-span" style="background-color: white; line-height: 19px;">it is possible that pAKT-ser</span><sup style="background-color: white; border-bottom-width: 0px; border-color: initial; border-left-width: 0px; border-right-width: 0px; border-style: initial; border-top-width: 0px; line-height: 0; margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0px; outline-style: none; padding-bottom: 0px; padding-left: 0px; padding-right: 0px; padding-top: 0px; position: relative; top: -0.6em; vertical-align: baseline;">473</sup><span class="Apple-style-span" style="background-color: white; line-height: 19px;"> is involved in the physiological adaptation to fasting, inducing a reduction in peripheral glucose uptake and protecting the body from hypoglycemia."</span></span></blockquote>
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Intramyocellular triglyceride accumulation is thought to mediate fatty acid insulin resistance. This is one way by which some authors think that a high-fat diet leads to insulin resistance. Compared to fasting (67h) a very low carbohydrate diet (<u>eucaloric</u>) produces the same amount of IMTG accumulation, both produce glucose intolerance and reductions in insulin sensitivity (<a href="http://www.ncbi.nlm.nih.gov/pubmed/16627573">14</a>). Thus, the factor for triggering this metabolic response seems to be the absence (or drastic reduction) in glucose availability (my bolds):</div>
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<span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;">"<span class="Apple-style-span" style="background-color: white; line-height: 19px;">Thus, we suggest that <b>dietary-induced IMTG accumulation and insulin resistance in healthy humans may be largely influenced by circulating FFAs, whose availability (in turn) is regulated by dietary CHO intake</b>. (...) </span><span class="Apple-style-span" style="background-color: white; line-height: 19px;">our study provides support for the hypothesis that <b>the </b></span><em style="background-color: white; border-bottom-width: 0px; border-color: initial; border-left-width: 0px; border-right-width: 0px; border-style: initial; border-top-width: 0px; line-height: 19px; margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0px; outline-style: none; padding-bottom: 0px; padding-left: 0px; padding-right: 0px; padding-top: 0px; vertical-align: baseline;"><b>physiological</b></em><span class="Apple-style-span" style="background-color: white; line-height: 19px;"><b> trigger for this coupling in the healthy individual may be a short-term challenge to dietary CHO availability</b>. That we have observed these diabetogenic alterations in a physically fit population, which is purported to be insulin sensitive yet exhibits high IMTG concentrations (the ‘athlete paradox’) (</span><a class="xref-bibr" href="http://ep.physoc.org/content/91/4/693.full#ref-16" id="xref-ref-16-2" style="background-color: white; border-bottom-width: 0px; border-color: initial; border-left-width: 0px; border-right-width: 0px; border-style: initial; border-top-width: 0px; color: #00274c; line-height: 19px; margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0px; outline-style: none; padding-bottom: 0px; padding-left: 0px; padding-right: 0px; padding-top: 0px; text-decoration: none; vertical-align: baseline;">Goodpaster <em style="border-bottom-width: 0px; border-color: initial; border-left-width: 0px; border-right-width: 0px; border-style: initial; border-top-width: 0px; line-height: inherit; margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0px; outline-style: none; padding-bottom: 0px; padding-left: 0px; padding-right: 0px; padding-top: 0px; text-align: inherit; vertical-align: baseline;">et al.</em> 2001</a><span class="Apple-style-span" style="background-color: white; line-height: 19px;">), supports our contention that they represent an <b>adaptive rather than pathological response</b>. This substantiates our previous assertion that alterations in glucose tolerance and insulin sensitivity associated with dynamic changes to the plasma and/or lean tissue lipid profile are part of a </span><em style="background-color: white; border-bottom-width: 0px; border-color: initial; border-left-width: 0px; border-right-width: 0px; border-style: initial; border-top-width: 0px; line-height: 19px; margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0px; outline-style: none; padding-bottom: 0px; padding-left: 0px; padding-right: 0px; padding-top: 0px; vertical-align: baseline;"><b>normal</b></em><span class="Apple-style-span" style="background-color: white; line-height: 19px;"><b> co-ordinated adaptation to short-term changes in food availability</b> (</span><a class="xref-bibr" href="http://ep.physoc.org/content/91/4/693.full#ref-41" id="xref-ref-41-2" style="background-color: white; border-bottom-width: 0px; border-color: initial; border-left-width: 0px; border-right-width: 0px; border-style: initial; border-top-width: 0px; color: #00274c; line-height: 19px; margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0px; outline-style: none; padding-bottom: 0px; padding-left: 0px; padding-right: 0px; padding-top: 0px; text-decoration: none; vertical-align: baseline;">Stannard & Johnson, 2004</a><span class="Apple-style-span" style="background-color: white; line-height: 19px;">) and perhaps, more specifically, to <b>fluctuations of dietary CHO availability</b>.</span> (...) <span class="Apple-style-span" style="background-color: white; line-height: 19px;">This short-term alteration is teleologically sound because it limits competition between skeletal muscle and glucose obligate tissues for circulating glucose substrate when its availability becomes limited. Irrespective of a causal relationship, the coupling between IMTG accumulation and reduced insulin sensitivity may also represent a co-ordinated adaptive (non-pathological) response to CHO stress </span><span class="Apple-style-span" style="background-color: white; line-height: 19px;"> (</span><a class="xref-bibr" href="http://ep.physoc.org/content/91/4/693.full#ref-21" id="xref-ref-21-2" style="background-color: white; border-bottom-width: 0px; border-color: initial; border-left-width: 0px; border-right-width: 0px; border-style: initial; border-top-width: 0px; color: #00274c; line-height: 19px; margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0px; outline-style: none; padding-bottom: 0px; padding-left: 0px; padding-right: 0px; padding-top: 0px; text-decoration: none; vertical-align: baseline;">Johnson <em style="border-bottom-width: 0px; border-color: initial; border-left-width: 0px; border-right-width: 0px; border-style: initial; border-top-width: 0px; line-height: inherit; margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0px; outline-style: none; padding-bottom: 0px; padding-left: 0px; padding-right: 0px; padding-top: 0px; text-align: inherit; vertical-align: baseline;">et al.</em> 2003</a><span class="Apple-style-span" style="background-color: white; line-height: 19px;">). </span><span class="Apple-style-span" style="background-color: white; line-height: 19px;"><b>A concomitant resistance in muscle to the effects of insulin on glucose uptake during CHO stress maintains normoglycaemia and thus the preservation of plasma glucose for use by the CNS and glucose-obligate tissues</b> (</span><a class="xref-bibr" href="http://ep.physoc.org/content/91/4/693.full#ref-33" id="xref-ref-33-1" style="background-color: white; border-bottom-width: 0px; border-color: initial; border-left-width: 0px; border-right-width: 0px; border-style: initial; border-top-width: 0px; color: #00274c; line-height: 19px; margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0px; outline-style: none; padding-bottom: 0px; padding-left: 0px; padding-right: 0px; padding-top: 0px; text-decoration: none; vertical-align: baseline;">Reaven, 1998</a><span class="Apple-style-span" style="background-color: white; line-height: 19px;">). Dissociation of insulin action by way of muscle insulin resistance rather than attenuation of insulin secretion means that residual circulating insulin levels can be maintained (</span><a class="xref-bibr" href="http://ep.physoc.org/content/91/4/693.full#ref-23" id="xref-ref-23-2" style="background-color: white; border-bottom-width: 0px; border-color: initial; border-left-width: 0px; border-right-width: 0px; border-style: initial; border-top-width: 0px; color: #00274c; line-height: 19px; margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0px; outline-style: none; padding-bottom: 0px; padding-left: 0px; padding-right: 0px; padding-top: 0px; text-decoration: none; vertical-align: baseline;">Klein <em style="border-bottom-width: 0px; border-color: initial; border-left-width: 0px; border-right-width: 0px; border-style: initial; border-top-width: 0px; line-height: inherit; margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0px; outline-style: none; padding-bottom: 0px; padding-left: 0px; padding-right: 0px; padding-top: 0px; text-align: inherit; vertical-align: baseline;">et al.</em> 1993</a><span class="Apple-style-span" style="background-color: white; line-height: 19px;">), thereby preventing rampant proteolysis (</span><a class="xref-bibr" href="http://ep.physoc.org/content/91/4/693.full#ref-12" id="xref-ref-12-1" style="background-color: white; border-bottom-width: 0px; border-color: initial; border-left-width: 0px; border-right-width: 0px; border-style: initial; border-top-width: 0px; color: #00274c; line-height: 19px; margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0px; outline-style: none; padding-bottom: 0px; padding-left: 0px; padding-right: 0px; padding-top: 0px; text-decoration: none; vertical-align: baseline;">Fryburg <em style="border-bottom-width: 0px; border-color: initial; border-left-width: 0px; border-right-width: 0px; border-style: initial; border-top-width: 0px; line-height: inherit; margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0px; outline-style: none; padding-bottom: 0px; padding-left: 0px; padding-right: 0px; padding-top: 0px; text-align: inherit; vertical-align: baseline;">et al.</em> 1990</a><span class="Apple-style-span" style="background-color: white; line-height: 19px;">), lipolysis (</span><a class="xref-bibr" href="http://ep.physoc.org/content/91/4/693.full#ref-22" id="xref-ref-22-1" style="background-color: white; border-bottom-width: 0px; border-color: initial; border-left-width: 0px; border-right-width: 0px; border-style: initial; border-top-width: 0px; color: #00274c; line-height: 19px; margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0px; outline-style: none; padding-bottom: 0px; padding-left: 0px; padding-right: 0px; padding-top: 0px; text-decoration: none; vertical-align: baseline;">Kather <em style="border-bottom-width: 0px; border-color: initial; border-left-width: 0px; border-right-width: 0px; border-style: initial; border-top-width: 0px; line-height: inherit; margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0px; outline-style: none; padding-bottom: 0px; padding-left: 0px; padding-right: 0px; padding-top: 0px; text-align: inherit; vertical-align: baseline;">et al.</em> 1985</a><span class="Apple-style-span" style="background-color: white; line-height: 19px;">) and perhaps hepatic glucose release, whilst unnecessary uptake of blood glucose by muscle is prevented."</span></span></blockquote>
<span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;">So, from the studies above, we can conclude that:</span><br />
<br />
<ul>
<li><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;">FFA supress glucose uptake and oxidation, resulting in muscular insulin resistance, without reducing insulin secretion.</span></li>
<li><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;">These effects seem to be dependent on dietary carbohydrate restriction.</span></li>
<li><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;">FFA-induced muscular insulin resistance is a physiological response to low availability of glucose. </span></li>
<li><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;">Under <b>normal</b> conditions, this serves to maintain adequate BG levels. When FFA are in excess, there might be a rise in BG levels, because oxidation and release of FFA are not coupled. This leads to insulin resistance in other tissues like the liver (<a href="http://www.ncbi.nlm.nih.gov/pubmed/12531742">15</a>), consequently failing to control hepatic glucose output.</span></li>
</ul>
<br />
<div style="font-family: 'Trebuchet MS', sans-serif;">
<u>Blood glucose levels and high carbohydrate diets</u></div>
<div style="font-family: 'Trebuchet MS', sans-serif;">
<u><br /></u></div>
<div style="font-family: 'Trebuchet MS', sans-serif;">
Without any biochemical explanation, logic dictates that if we eat a high carbohydrate diet, glucose oxidation pathways are stimulated. This is the opposite of what we observe with carbohydrate restriction, that is, stimulation of insulin signaling. Glucose and insulin both regulate GLUT4 and GLUT1 in muscle cells (<a href="http://www.ncbi.nlm.nih.gov/pubmed/1990010">16</a>) to increase glucose uptake. The Randle cycle dictates that glucose stimulates its own oxidation and reduces fatty acid utilization. As shown above, glucose reduces PDK and increases PDH. Insulin inhibits lipolysis, further facilitating glucose oxidation. In <u>healthy</u> subjects, a high carbohydrate-low fat diet can improve insulin sensitivity (<a href="http://www.ncbi.nlm.nih.gov/pubmed/11719836">17</a>, <a href="http://www.ncbi.nlm.nih.gov/pubmed/9867084">18</a>). It makes sense, carbohydrates supress fat oxidation and increse glucose oxidation. Overall, there should not be a rise in BG levels on a 24h basis, if anything, we can expect a reduction, because we are utilizing glucose as our main substrate. </div>
<div style="font-family: 'Trebuchet MS', sans-serif;">
<br /></div>
<div style="font-family: 'Trebuchet MS', sans-serif;">
<u>The common ground: calorie restriction</u></div>
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<u><br /></u></div>
<div style="font-family: 'Trebuchet MS', sans-serif;">
Until now, we have seen that carbohydrates stimulate glucose utilization (insulin sensitivity) and that FFA supress it. How can then a ketogenic diet produce such good results in people with diabetes? Diabetes and MetSyn are characterized by lipotoxicity and glucotoxicity (<a href="http://www.lucastafur.com/2011/02/integrative-metabolism-physiology-case_03.html">19</a>). This means that there is an abnormal level of plasma FFA and glucose, produced by PaIR. Insulin cant supress hepatic glucose output, muscle cells do not respond to insulin, and adipocytes liberate FFA in an uncontrolled fashion. In very simple terms, there is an excess of both energy substrates, each one inhibiting the utilization of the other. This scenario can be improved both by restricting fat (thereby increasing glucose utilization) or restricting carbohydrates (increasing fat utilization). In either case, calories must be restricted (directly or indirectly). So, people who show signs of glucose intolerance and switch to a ketogenic diet can improve their BG and insulin levels (by reducing glucotoxicity), but if energy is in excess, BG can start to rise. On the contrary, reducing dietary fat alleviates lipotoxicity, increasing insulin sensitivity. This is why any diet which is calorie restricted, independent of macronutrient composition, produces weight loss and improves glucoregulation. Calorie restriction, by producing a calorie deficit, alleviates both gluco- and lipotoxicity. </div>
<div style="font-family: 'Trebuchet MS', sans-serif;">
<br /></div>
<div>
<div style="font-family: 'Trebuchet MS', sans-serif;">
One of the important aspects for dealing with this subject is the fact that glucose intolerance can have many underlying causes. In this manner, a person with autoimmune diabetes may not tolerate carbohydrates as well as a person with only mild PaIR. The fact that PaIR may progress into beta-cell dysfunction (<a href="http://www.ncbi.nlm.nih.gov/pubmed/12637977">20</a>, <a href="http://www.ncbi.nlm.nih.gov/pubmed/16823478/">21</a>) can alterate the response to a high carbohydrate diet, and depending on the severity, extreme measures must be taken to achieve normal BG and insulin levels (such as severe calorie restriction). The distribution of body fat can also have consequences on glucoregulation (<a href="http://www.lucastafur.com/2011/12/getting-fat-type-matters.html">22</a>). Last but not least, epigenetic changes produced <i>in utero</i> can affect glucose tolerance since the moment we are born (<a href="http://www.ncbi.nlm.nih.gov/pubmed/15128277">23</a>). </div>
<div style="font-family: 'Trebuchet MS', sans-serif;">
<br /></div>
<div style="font-family: 'Trebuchet MS', sans-serif;">
What is more important, in my opinion, is to address whether hyperinsulinemia causes or potentiates IR, or if hyperinsulinemia results from IR, by a compensatory mechanism. If the first hypothesis holds true, then a ketogenic diet would have an advantage over a low fat-high carbohydrate diet. Desensitization of target cells triggered by the same hormone (homologous desensitization) is a very common characteristic of hormone signaling. In short, high levels of a given hormone reduce the response of the cell to the hormone effects and a reduction in the level of this hormone resets sensitivity. Excess hormone signaling is harmful, so the cell's attempt to restore normality is mediated by reducing its response. This is exactly what happens with insulin: </div>
<ul>
<li><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;">Chronic hyperinsulinemia (<i>in vivo </i>and <i>in vitro</i>) causes a reduction in the number of receptors per cell and glucose transport (<a href="http://www.ncbi.nlm.nih.gov/pubmed/4359334">24</a>, <a href="http://www.ncbi.nlm.nih.gov/pubmed/6999035">25</a>).</span></li>
<li><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;">Pre-incubation of 3T3-L1 adipocytes with high levels of insulin and glucose increase PTEN activity, which is correlated with decreased PtdIns(3,4,5)P3 (<a href="http://www.ncbi.nlm.nih.gov/pubmed/18303120">26</a>). This metabolite is very important for intracellular signaling transduction of insulin.</span></li>
<li><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;">Hyperinsulinemia has shown to induce insulin resistance in humans (<a href="http://www.ncbi.nlm.nih.gov/pubmed/3884419">27</a>).</span></li>
<li><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;">Overall, hyperinsulinemia is proposed to be a result and a driver of insulin resistance (<a href="http://www.ncbi.nlm.nih.gov/pubmed/18227495">28</a>).</span></li>
</ul>
<span style="font-family: 'Trebuchet MS', sans-serif;">Obesity seems to be characterized by an increased amount of insulin being secreted, compared to lean subjects (<a href="http://www.ncbi.nlm.nih.gov/pubmed/21633180">29</a>). So, while calorie restriction <i>per se</i> is responsible for improved glucoregulation, there might be a short-term benefit in consuming a high-fat ketogenic diet in T2DM and MetSyn patients. As the bodyfat mass and associated hormones regulate, the differences between hypocaloric diets with different macronutrient profiles might be eliminated. This seems reasonable for diet-induced insulin resistance, but not for autoimmune or severe diet-induced glucose intolerance. There seems to be a threshold in which many people cant fully recover their insulin sensitivity with dietary measures. This is where a more integrative and previously uncharacterized approach kicks in (this is the subject of my future post). </span></div>
<div>
<span style="font-family: 'Trebuchet MS', sans-serif;"><br /></span></div>
<div>
<span style="font-family: 'Trebuchet MS', sans-serif;"><u>Glucose and cancer</u></span></div>
<div>
<span style="font-family: 'Trebuchet MS', sans-serif;"><br /></span></div>
<div>
<span style="font-family: 'Trebuchet MS', sans-serif;">Glucose restriction for cancer treatment seems reasonable given the evidence on the dependence of most types of cancer on glucose for cell growth and proliferation. Unfortunately, the picture is not that simple (<a href="http://www.lucastafur.com/2011/11/glucose-restriction-and-tsc.html">30</a>). Although restricting glucose is a good idea, specially for glucose-dependent tumors, the evidence shows that cancer cells also feed on glutamine. More surprinsingly, some types of cancer can grow on fatty acids (<a href="http://www.ncbi.nlm.nih.gov/pubmed/22037646">31</a>). Restricting glucose reduces insulin levels, which promotes cancer growth. Nevertheless, ideal levels of blood glucose and insulin for treating cancer can only be achieved via calorie restriction. In fact, many supporters of ketogenic diets for cancer often cite the study of Zuccoli et al (<a href="http://www.ncbi.nlm.nih.gov/pubmed/20412570/">32</a>) on the management of glioblastoma. But very few mention what is stated in the study:</span></div>
<blockquote class="tr_bq">
<span style="font-family: 'Trebuchet MS', sans-serif;">"</span><span style="background-color: #f8f8f8; line-height: 22px; text-align: -webkit-auto;"><span style="font-family: 'Trebuchet MS', sans-serif;">Due to the hyperuricemia <b>the patient was gradually shifted to a calorie restricted non-ketogenic diet</b>, which also delivered a total of about 600 kcal/day. This diet maintained low blood glucose levels and slightly elevated (++) urine ketone levels due to the low calorie content of the diet."</span></span></blockquote>
<div>
<div style="font-family: 'Trebuchet MS', sans-serif;">
Despite switching to a non-ketogenic (by definition) diet, the patient still showed progress. In my opinion, besides glucose and protein restriction, calorie restriction (and probably fasting) is the dominant factor for achieving success during cancer treatment. </div>
<div>
<div style="font-family: 'Trebuchet MS', sans-serif;">
<br /></div>
<div style="font-family: 'Trebuchet MS', sans-serif;">
<u>Summary and key points</u></div>
<br />
<ul>
<li><span style="font-family: 'Trebuchet MS', sans-serif;">Both energy substrates (glucose and fatty acids) support their own oxidation and inhibit the metabolism of the other.</span></li>
<li><span style="font-family: 'Trebuchet MS', sans-serif;">A diet high in fat and low in carbohydrates will reduce glucose metabolism and increase fat metabolism. Conversely, a high carbohydrate-low fat diet increases glucose utilization and decreases fatty acid metabolism.</span></li>
<li><span style="font-family: 'Trebuchet MS', sans-serif;">Increased glucose utilization implies upregulation of glucose membrane transporters and enzymes involved in glycolysis. Additionally, it reduces the activity of enzymes involved in fat metabolism. </span></li>
<li><span style="font-family: 'Trebuchet MS', sans-serif;">Increased fatty acid metabolism inhibits key glycolytic enzymes, as well as GLUT membrane translocation. It also interrupts glucose/insulin signaling and stimulates lipolytic enzymes. </span></li>
<li><span style="font-family: 'Trebuchet MS', sans-serif;">Chronic hyperinsulinemia, caused by peripheral insulin resistance and energy excess, aggraviates glucose intolerance. Both high glucose and high FFA levels promote this state, by different mechanisms. </span></li>
<li><span style="font-family: 'Trebuchet MS', sans-serif;">Under energy balance, a high fat ketogenic diet might produce muscular insulin resistance, reducing glucose tolerance. This should not be compensated by an increase in blood glucose levels. However, if energy intake exceeds calorie expenditure and/or the body utilizes predominantely FFA for energy for extendend periods of time, there can be a rise in blood glucose to non-pathological levels. This is specially relevant if there is little exercise being done (exercise promotes muscular insulin sensitivity) and/or there is an abnormal condition.</span></li>
<li><span style="font-family: 'Trebuchet MS', sans-serif;">The etiology of glucose intolerance is very important for the proper treatment. Although calorie restriction is the primary solution for obesity/diet-induced insulin resistance, people with autoimmune (both congenital/perinatal or diet-induced) and beta cell dysfunction should adopt a very low carb approach. </span></li>
</ul>
<span style="font-family: 'Trebuchet MS', sans-serif;">In the end, the level of carbohydrates proposed by the Jaminet's is in the safe side. The alarmism promoted by some people is not supported. While severely restricting carbohydrates is, in my opinion, the best approach for MetSyn and obesity, once fat mass has reduced, one can tolerate more carbohydrate without problems. If the choice is restricting carbohydrates for life, you should expect a very abnormal response to any carbohydrate (being "safe" or "unsafe"). Nevertheless, lets not forget that the <a href="http://perfecthealthdiet.com/">Perfect Health Diet</a> is not a high carbohydrate diet, but a high-fat, low carbohydrate diet. Despite my obvious differences with Paul (<a href="http://www.lucastafur.com/search/label/ketomyths">33</a>), his dietary advise is very reasonable and his diet is the first I recommend. This template, plus calorie restriction and/or fasting, is the best dietary measure one can implement. Everyone should adjust their individual carbohydrate needs, but in the end, the key is controlling and preventing inflammation. And carbohydrates <i>per se</i> are not inflammatory. </span><br />
<span style="font-family: 'Trebuchet MS', sans-serif;"><br /></span><br />
<span style="font-family: 'Trebuchet MS', sans-serif;">*Certainly, there are people who are in the extremes of the Gaussian distribution. For these persons, extra measures should be taken. I will write about my approach in the following post. </span></div>
</div>
</div>Anonymousnoreply@blogger.com22tag:blogger.com,1999:blog-4724838399830873886.post-65795614558658401622011-12-22T16:31:00.000-08:002017-03-13T06:07:40.213-07:00No time except for...<div style="text-align: justify;">
<span style="font-family: 'Trebuchet MS', sans-serif;">...finishing my project. I have to present a draft of my thesis research on January 16th, so I dont have much time to read any paper not related to it.</span></div>
<div style="text-align: justify;">
<span style="font-family: 'Trebuchet MS', sans-serif;"><br /></span></div>
<div style="text-align: justify;">
<span style="font-family: 'Trebuchet MS', sans-serif;">After that, hopefully I will be able to finish a few pending posts. </span></div>
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<span style="font-family: 'Trebuchet MS', sans-serif;"><br /></span></div>
<div style="text-align: justify;">
<span style="font-family: 'Trebuchet MS', sans-serif;">Happy holidays!</span></div>Anonymousnoreply@blogger.com3tag:blogger.com,1999:blog-4724838399830873886.post-77084148414180178292011-12-06T10:14:00.001-08:002017-03-13T06:07:40.223-07:00Getting fat: the type matters<div style="text-align: justify;">
<span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;">Traditionally, increased fat mass has been viewed as unhealthy irrespective of the distribution of body fat. With increasing research on the subject, most researchers agree that increased visceral adipose tissue (VAT) is the main determinant of the metabolic disorders associated with obesity, compared to increased subcutaneous adipose tissue (SAT). </span></div>
<div style="text-align: justify;">
<span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"><br /></span></div>
<div style="text-align: justify;">
<span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;">In the last months, there has been a not-so-scientific debate on whether being fat eating a "healthy" diet is better than being thin eating a Western diet. One can be healthy even with an increased body fat mass? Is gaining fat with a given diet different than with another diet?</span></div>
<div style="text-align: justify;">
<span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"><br /></span></div>
<div style="text-align: justify;">
<span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;">A study done by Tran et al. (<a href="http://www.ncbi.nlm.nih.gov/pubmed/18460332">1</a>) caught my attention and motivated me to dig a little further in this topic. The authors found that transplantation of SAT and VAT to the subcutaneous or visceral regions of recipient mice produced remarkable differences on glucose homeostasis, weight and body fat gain. The scheme utilized for the transplants is shown below:</span></div>
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<span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"><br /></span></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://1.bp.blogspot.com/-S0Vmblbs2nI/Tt5kr-mBDmI/AAAAAAAAACU/J6dBAfTsOPY/s1600/VISC.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="320" src="http://1.bp.blogspot.com/-S0Vmblbs2nI/Tt5kr-mBDmI/AAAAAAAAACU/J6dBAfTsOPY/s320/VISC.png" width="230" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span class="Apple-style-span" style="background-color: white; font-family: arial, verdana, helvetica, sans-serif; font-size: 12px;">Copyright © 2008 Elsevier Inc. All rights reserved.</span></td></tr>
</tbody></table>
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<span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"><br /></span></div>
<div style="text-align: justify;">
<span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;">The most important effect was noticed in SC-VIS mice, which were transplanted with SAT into the visceral cavity. Compared to other mice, the rate of body weight gain (fat was transplanted "on top" of endogenous adipose tissue) was significantly lower, gaining on average only 63% and 59% (they used two cohorts) of the amount gained by sham-mice at the end of the study. This was irrespective of calorie intake, energy expenditure or heat production. Basal plasma glucose levels were reduced by 15% and plasma insulin levels were reduced by 33% in SC-VIS mice. Compared to sham, SC-VIS mice had 70% lower plasma leptin levels, but adiponectin was also decreased. Intraperitoneal glucose tolerance tests showed that SC-VIS mice had the lowest glucose levels, and insulin sensitivity (assessed by hyperinsulinemic-euglycemic clamp) was higher in this group. Glucose uptake in endogenous SAT was increased in both groups of mice transplanted with SAT, reflecting an increase in insulin sensitivity. Finally, gene expression of adiponectin, resistin and leptin levels were decreased in SC-VIS mice, compared to sham. </span></div>
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<span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"><br /></span></div>
<div style="text-align: justify;">
<span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;">Overall, the study findings were:</span></div>
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<span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"><br /></span></div>
<div style="text-align: justify;">
</div>
<ul>
<li><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;">Transplantation of SAT into the visceral cavity produced the most significant results in terms of weight gain, glucose tolerance and adipocytokine levels.</span></li>
<li><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;">SC-VIS mice had decreased body weight, decreased body fat percentage, increased percent of lean mass, without significant changes in total energy expenditure or heat production.</span></li>
<li><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;">Transplantation of SAT into recipient mice improved insulin sensitivity in the liver and in endogenous SAT. </span></li>
<li><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;">Transplantation of SAT into the visceral cavity decreased average adipocyte area by 38% compared to endogenous SAT, and did not increase the adipocyte's size to that of the endogenous VAT. </span></li>
<li><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;">Adding SAT to the visceral cavity reduced mRNA levels of resistin, leptin and adiponectin, compared to endogenous SAT.</span></li>
</ul>
<br />
<div style="text-align: justify;">
<span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;">These results suggest a "protective" role of SAT in obesity. There is evidence that insulin resistance correlates with VAT, regardless of bodyweight (<a href="http://www.ncbi.nlm.nih.gov/pubmed/11916919">2</a>). VAT appears to produce more IL-6 than SAT (<a href="http://www.ncbi.nlm.nih.gov/pubmed/9506738">3</a>), which correlates with increased macrophage infiltration in VAT compared to SAT (<a href="http://www.ncbi.nlm.nih.gov/pubmed/17374712">4</a>). Liposuction, despite reducing bodyfat levels, does not improve metabolic markers in the short and long term (<a href="http://www.ncbi.nlm.nih.gov/pubmed/18820648">5</a>), does not improve insulin sensitivity of muscle, liver or adipose tissue; and doesn't affect levels of C-reactive protein, IL-6, TNFa and adiponectin in diabetic or normal subjects (<a href="http://www.ncbi.nlm.nih.gov/pubmed/15201411">6</a>). Accordingly, SAT seems to modulate TNFa expression in VAT (<a href="http://www.ncbi.nlm.nih.gov/pubmed/17075771">7</a>). </span></div>
<div style="text-align: justify;">
<span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"><br /></span></div>
<div style="text-align: justify;">
<span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;">Thus, it seems that it is not weight lost <i>per se</i> which is important for preventing metabolic damage, but the type of body fat lost. Liposuction achieves equal or greater weight loss than lifestyle modifications, but fails to improve metabolic parameters. </span></div>
<div style="text-align: justify;">
<span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"><br /></span></div>
<div style="text-align: justify;">
<span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"><u>Effect of different diets on body fat distribution</u></span></div>
<div style="text-align: justify;">
<span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"><br /></span></div>
<div style="text-align: justify;">
<span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;">From the above discussion, it is reasonable to think that the best diet is the one that a. decreases body fat mass and b. reduces and/or redistributes fat mass towards SAT.</span></div>
<div style="text-align: justify;">
<span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"><br /></span></div>
<div style="text-align: justify;">
<span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;">Active rats fed a ketogenic diet show increased SAT compared to matched carbohydrate-fed rats (<a href="http://www.ncbi.nlm.nih.gov/pubmed/19506567/">8</a>), despite similar body fat levels, although there are contradictory results (<a href="http://www.ncbi.nlm.nih.gov/pubmed/20057366">9</a>). Weight loss produced either by a high fat-low carbohydrate diet or a low fat-high carbohydrate diet show the same effects on both SAT and VAT (<a href="http://www.ncbi.nlm.nih.gov/pubmed/21400557">10</a>), suggesting that the macronutrient ratio is not important. This contrasts with a small study which showed that the visceral to subcutaneous fat ratio (V/S) decreased only in the low carbohydrate group (<a href="http://www.ncbi.nlm.nih.gov/pubmed/15331203">11</a>), compared with the group eating a high carbohydrate diet, even when both diets were hypocaloric. Other authors suggest that ketogenic diets decrease VAT more significantly than high carbohydrate diets (<a href="http://www.ncbi.nlm.nih.gov/sites/entrez/15533250">12</a>), although the method used to estimate VAT levels (DEXA) has some predictive problems (<a href="http://www.ncbi.nlm.nih.gov/pubmed/14694213">13</a>). </span></div>
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<span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"><br /></span></div>
<div style="text-align: justify;">
<span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;">Chaston and Dixon (<a href="http://www.ncbi.nlm.nih.gov/pubmed/18180786">14</a>) have proposed that acute caloric restriction produces a preferential loss of VAT in the short term and that this effect is seen with modest weight loss. </span><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;">Alternate day fasting (ADF) has also shown to improve body fat distribution in mice, increasing the proportion of SAT vs. VAT and levels of adiponectin, and reducing the levels of leptin and resistin (<a href="http://www.ncbi.nlm.nih.gov/pubmed/19195863">15</a>, </span><a href="http://www.ncbi.nlm.nih.gov/pubmed/19195863" style="font-family: 'Trebuchet MS', sans-serif;">16</a><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;">). These effects seem to be independent of the diet and body fat loss.</span></div>
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<span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"><br /></span></div>
<div style="text-align: justify;">
<span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"><u>Summing up</u></span><br />
<div style="text-align: justify;">
<span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"><br /></span></div>
<span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;">Independent of total body fat, there seems to be a protective effect of SAT vs. VAT. This might be the reason why not all obese people develop metabolic syndrome or insulin resistance (<a href="http://www.ncbi.nlm.nih.gov/pubmed/20395951">17</a>), as healthy obese subjects seem to have less risk for complications than normal-weight subjects with metabolic syndrome (<a href="http://www.ncbi.nlm.nih.gov/pubmed/21920263">18</a>). Calorie restriction seems to be the most important factor for preventing an increase in VAT, while ADF might provide an additional benefit without weight loss. From the above, we can try to answer the questions proposed: </span><br />
<div style="text-align: justify;">
<span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"><br /></span></div>
<span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;">One can be healthy even with an increased body fat mass? </span><br />
<div style="text-align: justify;">
<span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"><br /></span></div>
<span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;">Yes, given a proper body fat distribution (higher proportion of SAT vs. VAT).</span><br />
<div style="text-align: justify;">
<span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"><br /></span></div>
<span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;">Is gaining fat with a given diet different than with another diet?</span><br />
<div style="text-align: justify;">
<span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"><br /></span></div>
<span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;">Possibly. Overfeeding studies done do not control for macronutrient composition, so there is no evidence of a different effect of different diets. However, from the studies available, gaining body fat while implementing ADF might be different than with a Western diet. Moreover, specific nutrients might have different effects regardless of body fat gain, such as fructose (<a href="http://www.ncbi.nlm.nih.gov/pubmed/20663467/">19</a>), although recent evidence do not show adverse effects of overfeeding fructose on visceral fat (<a href="http://www.ncbi.nlm.nih.gov/pubmed/21396140">20</a>). In either case, having a normal-weight is not protective for cardiometabolic abnormalities (<a href="http://www.ncbi.nlm.nih.gov/pubmed/18695075">21</a>). This suggests that dietary habits are important even in the absence of weight gain (normal-weight obesity), and that gaining weight with a healthy diet might not be as detrimental as gaining weight with a Western diet.</span></div>
<div style="text-align: justify;">
<span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"><br /></span></div>
<span style="float: left; padding-bottom: 5px; padding-left: 5px; padding-right: 5px; padding-top: 5px;"><a href="http://www.researchblogging.org/"><img alt="ResearchBlogging.org" src="http://www.researchblogging.org/public/citation_icons/rb2_large_white.png" style="border: 0;" /></a></span><span class="Z3988" title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.jtitle=Cell+metabolism&rft_id=info%3Apmid%2F18460332&rfr_id=info%3Asid%2Fresearchblogging.org&rft.atitle=Beneficial+effects+of+subcutaneous+fat+transplantation+on+metabolism.&rft.issn=1550-4131&rft.date=2008&rft.volume=7&rft.issue=5&rft.spage=410&rft.epage=20&rft.artnum=&rft.au=Tran+TT&rft.au=Yamamoto+Y&rft.au=Gesta+S&rft.au=Kahn+CR&rfe_dat=bpr3.included=1;bpr3.tags=Health%2CBiology%2C+Nutrition">Tran TT, Yamamoto Y, Gesta S, & Kahn CR (2008). Beneficial effects of subcutaneous fat transplantation on metabolism. <span style="font-style: italic;">Cell metabolism, 7</span> (5), 410-20 PMID: <a href="http://www.ncbi.nlm.nih.gov/pubmed/18460332" rev="review">18460332</a></span>Anonymousnoreply@blogger.com8tag:blogger.com,1999:blog-4724838399830873886.post-48880639770826331222011-11-22T08:29:00.001-08:002017-03-13T06:07:40.203-07:00The gut microbiota regulates the metabolic response to fasting<div style="text-align: justify;">
<span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;">Metabolic</span><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;"> </span><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;">adaptation to fasting is an essential mechanism developed by mammals in order to survive. The transition from the fed to the fasted state is tightly regulated. This metabolic shift includes reducing glucose oxidation and storage, and increasing the supply of free fatty acids (FFA) and ketone bodies (KB) to peripheral tissues. Glucose is spared for obligate glucose-consuming cells (such as some neurons, erythrocytes, kidney cells) by FFA's effects on membrane glucose transporters in peripheral tissues, upregulation of lipolytic enzymes and downregulation of glycolytic enzymes. Overall, if extended, fasting will produce a state of peripheral insulin resistance, which implies that skeletal muscle will become desensitized to insulin's effect, thereby reducing glucose transport into cells. However, this scenario differs from that observed during pathological insulin resistance, in which skeletal muscle, liver and adipose tissue are insulin resistant, so there is no control of glucose and FFA levels, leading to glucotoxicity and lipotoxicity.</span></div>
<div style="text-align: justify;">
<span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"><br /></span></div>
<div style="text-align: justify;">
<span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;">Healthy humans should be able to fast without problems (metabolic flexibility). If everything is working as supposed to, there should be no problem when switching to a predominantely lipolytic/ketogenic metabolism. How hard the transition to a fasting state is may be a marker of the functioning of intermediate metabolism. </span></div>
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<span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"><br /></span></div>
<div style="text-align: justify;">
<span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;">Crawford et al. (<a href="http://www.ncbi.nlm.nih.gov/pubmed/19549860/">1</a>) tested a basic hypothesis, based on previous findings:</span></div>
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<span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"><br /></span></div>
<div style="text-align: justify;">
</div>
<ul>
<li><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;">Germ-free (GF) mice are leaner than conventionally raised (CONV-R) mice, even when GF mice consume more food (<a href="http://www.ncbi.nlm.nih.gov/pubmed/15505215/">2</a>).</span></li>
<li><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;">Transplantation of the gut microbiota from obese mice to GF recipients causes a greater increase in adiposity than does a microbiota from lean mice (<a href="http://www.ncbi.nlm.nih.gov/pubmed/17183312">3</a>).</span></li>
</ul>
<span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;">
Overall, there seems to be an alteration in the composition and the microbiome of gut bacteria from obese mice, which increases energy harvest from available food. This is an aberration from its normal function, which is to provide an adequate amount of energy from otherwise indigestable nutrients. </span><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;">If true, then we might expect that this mechanism is beneficial to the host in periods of nutrient deprivation. If not, there would be no obvious evolutionary explanation for this symbiotic relationship. Accordingly, after withdrawal of nutrients, GF mice die more rapidly that CONV-R mice, even when the rate of body weight loss is the same (</span><a href="http://www.ncbi.nlm.nih.gov/pubmed/4866341" style="font-family: 'Trebuchet MS', sans-serif;">4</a><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;">). Because adaptation to fasting involves a shift towards ketogenesis, the gut microbiota might regulate this process.</span><br />
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<span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"><br /></span></div>
<div style="text-align: justify;">
<span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"><u>The gut microbiota regulates ketone body metabolism during fasting</u></span></div>
<div style="text-align: justify;">
<span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"><br /></span></div>
<div style="text-align: justify;">
<span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;">Compared to CONV-D*, GF mice showed 37% lower levels of serum betahydroxybutyrate (BHB) in the fasted state, with no differences in the fed state. Moreover, levels of insulin, glucose, FFA and triglycerides where unchanged. CONV-D mice had increased hepatic triglyceride stores compared to GF mice, difference which was enhanced dramatically with fasting. As expression of <i>Pnpla2 </i>was increased similarly in both CONV-D and GF mice, fasting-induced fatty acid mobilization was not impaired by the absence of gut microbiota. PPARa expression was higher in CONV-D than in GF mice, and the fasting-induced ketogenesis was impaired in CONV-D PPARa-/- mice. </span></div>
<div style="text-align: justify;">
<span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"><br /></span></div>
<div style="text-align: justify;">
<span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;">The liver produces BHB for utilization in peripheral tissues. It lacks the key enzyme 3-oxoacid CoA transferase, so is incapable of oxidizing ketone bodies. When fasted, GF mice had 50% less concentration of liver BHB compared to CONV-D mice. Expression of Fgf21 and Hmgcs2, both targets of PPARa which stimulate ketogenesis, was lower in fasted GF mice compared to CONV-D mice. </span></div>
<div style="text-align: justify;">
<span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"><br /></span></div>
<div style="text-align: justify;">
<span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;">These results suggest that <b>the gut microbiota stimulates ketogenesis during fasting by a PPARa-dependent mechanism</b>. Additionally, it promotes hepatic triacylglycerol synthesis and storage. </span></div>
<div style="text-align: justify;">
<span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"><br /></span></div>
<div style="text-align: justify;">
<span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;">There are two possible ways of generating acetyl CoA in the liver during a fast: from acetate produced in the gut and from oxidation of fatty acids from adipose tissue. In GF mice, the only source is the latter. Cecal acetate levels were very low in fed GF mice and 20-fold greater in CONV-D mice. During fasting, these levels were reduced in CONV-D, but remained significantly higher compared to GF mice, which showed no reduction. </span></div>
<div style="text-align: justify;">
<span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"><br /></span></div>
<div style="text-align: justify;">
<span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;">One unexpected result was the change in the microbiota composition induced by fasting. It was found that there was a <b>significant increase in the proportion of Bacteroidetes and a significant reduction in the proportion of Firmicutes.</b> Previous studies have found a correlation between a reduction in Bacteroidetes and an increase in Firmicutes with obesity (the high Firmicutes/low Bacteroidetes hypothesis) (<a href="http://www.ncbi.nlm.nih.gov/pubmed/18407065">5</a>, <a href="http://www.ncbi.nlm.nih.gov/pubmed/20101384">6</a>). </span></div>
<div style="text-align: justify;">
<span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"><br /></span></div>
<div style="text-align: justify;">
<span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"><u>The gut microbiota influences myocardial metabolism</u></span></div>
<div style="text-align: justify;">
<span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"><br /></span></div>
<div style="text-align: justify;">
<span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;">Analysis of the myocardial transcriptome of CONV-D and GF mice revealed an enrichment in the ketone body metabolic pathway in both groups, compared to their PPARa -/- counterparts. Expression of genes involved in fatty acid and ketone body metabolism were increased with fasting in both groups, but <i>Oxct1</i> gene expression was higher in CONV-D mice. Conversely, an increased <i>Glut1</i> expression was only observed in GF mice. </span></div>
<div style="text-align: justify;">
<span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"><br /></span></div>
<div style="text-align: justify;">
<span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;">The rate of glucose oxidation was significantly increased in isolated working hearts of GF mice, without alteration of fatty acid oxidation. In the absence of BHB, glucose utilization was also significantly greater. Glycogen levels were reduced in the myocardium of fasted GF mice compared to CONV-D mice, and there were no significant differences in heart rate, cardiac hydraulic work, mitochondrial morphology or number, or mitochondrial respiration. </span></div>
<div style="text-align: justify;">
<span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"><br /></span></div>
<div style="text-align: justify;">
<span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;">The shift towards a ketogenic metabolism in the myocardium is one hallmark of adaptation to fasting, as BHB is more energy efficient than glucose. So in periods of deprivation of nutrients, the myocardium maintains its normal functioning by using BHB instead of relying in glucose. <b>This adaptation is impaired in GF mice</b>.</span></div>
<div style="text-align: justify;">
<span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"><br /></span></div>
<div style="text-align: justify;">
<span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"><u>The gut microbiota affects myocardial mass</u></span></div>
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<span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"><u><br /></u></span></div>
<div style="text-align: justify;">
<span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;">Heart weight was reduced in fasted GF mice compared to CONV-D mice. Training elicits an hypertrophic response in the heart. However, this response was blunted in the absence of gut microbiota, as the hearts of trained GF mice remained smaller than the hearts of trained CONV-D mice. This correlated with alterations in a subset of pathways, which included ketone body metabolism. Administration of a ketogenic diet rescued heart weight in GF mice and shifted the myocardial transcriptome toward ketone body metabolism.</span></div>
<div style="text-align: justify;">
<span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"><u><br /></u></span></div>
<div style="text-align: justify;">
<span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;">These results suggest that<b> the gut microbiota is an important component for cardiovascular health</b>, and that <b>ketone bodies represent an essential substrate for the heart</b>. </span></div>
<div style="text-align: justify;">
<span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"><br /></span></div>
<div style="text-align: justify;">
<span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"><u>Summing up</u></span></div>
<div style="text-align: justify;">
<span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"><u><br /></u></span></div>
<div style="text-align: justify;">
<span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;">This is one of the most interesting studies that I have read lately. It provides a new template for the relationship between metabolism and gut microbiota, and shows the importance of gut bacteria for the normal response to fasting. I have summarized the findings of the study in the following figure (my interpretation):</span><br />
<span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"><br /></span></div>
<div style="text-align: justify;">
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://2.bp.blogspot.com/-hDqW90ZXRyY/TswWvHBUqII/AAAAAAAAACE/svkmiiRXnS8/s1600/Gutmicrobiotaketogenesis.bmp" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="253" src="http://2.bp.blogspot.com/-hDqW90ZXRyY/TswWvHBUqII/AAAAAAAAACE/svkmiiRXnS8/s400/Gutmicrobiotaketogenesis.bmp" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"><b>The gut microbiota regulates ketogenesis during fasting. </b>Fasting induces an increase in the proportion of Bacteroidetes and a reduction in the proportion of Firmicutes. These changes promote the production of acetate, which serves as substrate for hepatic acetyl CoA synthesis. The gut microbiota also stimulates hepatic triglyceride stores, providing another source of energy during fasting. The increase in acetyl CoA levels stimulates ketogenesis by a PPARa-dependent mechanism, increasing serum BHB levels. The elevated concentration of BHB levels supplied to the heart promotes the shift towards a ketone body-based metabolism, and inhibits glucose oxidation. Myocardial ketone body metabolism maintains myocardial mass and the normal hypertrophic response to exercise.</span></td></tr>
</tbody></table>
</div>
<div style="text-align: justify;">
<span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"><br /></span><br />
<span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;">* CONV-D (conventionalized) mice were transplanted with distal gut microbiota from CARB-fed CONV-R lean mice. </span></div>
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<span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"><br /></span></div>
<span style="float: left; padding-bottom: 5px; padding-left: 5px; padding-right: 5px; padding-top: 5px;"><a href="http://www.researchblogging.org/"><img alt="ResearchBlogging.org" src="http://www.researchblogging.org/public/citation_icons/rb2_large_gray.png" style="border: 0;" /></a></span><span class="Z3988" title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.jtitle=Proceedings+of+the+National+Academy+of+Sciences+of+the+United+States+of+America&rft_id=info%3Apmid%2F19549860&rfr_id=info%3Asid%2Fresearchblogging.org&rft.atitle=Regulation+of+myocardial+ketone+body+metabolism+by+the+gut+microbiota+during+nutrient+deprivation.&rft.issn=0027-8424&rft.date=2009&rft.volume=106&rft.issue=27&rft.spage=11276&rft.epage=81&rft.artnum=&rft.au=Crawford+PA&rft.au=Crowley+JR&rft.au=Sambandam+N&rft.au=Muegge+BD&rft.au=Costello+EK&rft.au=Hamady+M&rft.au=Knight+R&rft.au=Gordon+JI&rfe_dat=bpr3.included=1;bpr3.tags=Biology%2CNutrition%2C+Immunology%2C+Molecular+Biology">Crawford PA, Crowley JR, Sambandam N, Muegge BD, Costello EK, Hamady M, Knight R, & Gordon JI (2009). Regulation of myocardial ketone body metabolism by the gut microbiota during nutrient deprivation. <span style="font-style: italic;">Proceedings of the National Academy of Sciences of the United States of America, 106</span> (27), 11276-81 PMID: <a href="http://www.ncbi.nlm.nih.gov/pubmed/19549860" rev="review">19549860</a></span>Anonymousnoreply@blogger.com6tag:blogger.com,1999:blog-4724838399830873886.post-2435779320317618672011-11-15T17:03:00.001-08:002017-03-13T06:08:02.526-07:00Fecal bacteriotherapy<br />
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<span lang="EN-US" style="font-family: Georgia, serif;">Proper gut microbiota establishment begins in the
moment we are born and is shaped by lifestyle and environmental factors in
subsequent years. In some cases, the degree of dysbiosis is so severe that
there is not turning back and practical dietary/lifestyle recommendations are
useless.</span><span lang="EN-US" style="font-family: 'Times New Roman', serif;"><o:p></o:p></span></div>
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<br /></div>
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<u><span lang="EN-US" style="font-family: Georgia, serif;">Fecal bacteriotherapy</span></u><span lang="EN-US" style="font-family: 'Times New Roman', serif;"><o:p></o:p></span></div>
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<br /></div>
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<span lang="EN-US" style="font-family: Georgia, serif;">The logic behind this intervention is simple: it
tries to "reset" the gut microbiota. It has shown promising results
in intestinal bowel disease (IBD) and resistant</span><span lang="EN-US" style="font-family: Georgia, serif;"> </span><i><span lang="EN-US" style="font-family: Georgia, serif;">Clostridium difficile</span></i><span lang="EN-US" style="font-family: Georgia, serif;"> </span><span lang="EN-US" style="font-family: Georgia, serif;">infections. The following
protocol is taken from Silverman et al (</span><span style="font-family: Georgia, serif;"><a href="http://www.ncbi.nlm.nih.gov/pubmed/20117243">1</a></span><span lang="EN-US" style="font-family: Georgia, serif;">). My intent is to
facilitate information, not to encourage the realization of this protocol
without medical supervision. Interested persons should consult with their
doctors before doing any procedure of this nature. Donors and recipients should
be examined carefully before the intervention. The complete set of tests can be
consulted in the mentioned study.</span><span lang="EN-US" style="font-family: 'Times New Roman', serif;"><o:p></o:p></span></div>
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<br /></div>
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<u><span lang="EN-US" style="font-family: Georgia, serif;">Pretreatment</span></u><span lang="EN-US" style="font-family: 'Times New Roman', serif;"><o:p></o:p></span></div>
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<br /></div>
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<span lang="EN-US" style="font-family: Georgia, serif;">Recipients are initiated on maintenance therapy
with oral</span><span lang="EN-US" style="font-family: Georgia, serif;"> </span><i><span lang="EN-US" style="font-family: Georgia, serif;">Saccharomyces boulardii</span></i><span lang="EN-US" style="font-family: Georgia, serif;"> </span><span lang="EN-US" style="font-family: Georgia, serif;">(probiotic), 500mg orally,
twice per day. Metronidazole (500mg/3 times per day, PO) or vancomycin (125mg/4
times per day, PO) are also used. Both are antibiotics normally used against</span><span lang="EN-US" style="font-family: Georgia, serif;"> </span><i><span lang="EN-US" style="font-family: Georgia, serif;">C.difficile</span></i><span lang="EN-US" style="font-family: Georgia, serif;"> </span><span lang="EN-US" style="font-family: Georgia, serif;">infections.</span><span lang="EN-US" style="font-family: 'Times New Roman', serif;"><o:p></o:p></span></div>
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<u><span lang="EN-US" style="font-family: Georgia, serif;">Equipment</span></u><span lang="EN-US" style="font-family: 'Times New Roman', serif;"><o:p></o:p></span></div>
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<br /></div>
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<span lang="EN-US" style="font-family: Georgia, serif;">- 1 bottle of normal saline (200mL)</span><span lang="EN-US" style="font-family: 'Times New Roman', serif;"><o:p></o:p></span></div>
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<span lang="EN-US" style="font-family: Georgia, serif;">- 2 standard 2 quart enema bag kits (available at
drug stores)</span><span lang="EN-US" style="font-family: 'Times New Roman', serif;"><o:p></o:p></span></div>
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<span lang="EN-US" style="font-family: Georgia, serif;">- 3 standard kitchend blenders (1L capacity) with
markings for volume</span><span lang="EN-US" style="font-family: 'Times New Roman', serif;"><o:p></o:p></span></div>
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<br /></div>
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<u><span lang="EN-US" style="font-family: Georgia, serif;">Procedure</span></u><span lang="EN-US" style="font-family: 'Times New Roman', serif;"><o:p></o:p></span></div>
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<br /></div>
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<span lang="EN-US" style="font-family: Georgia, serif;">- Vancomycin/metronidazole should be stopped 24-48
hours before procedure.</span><span lang="EN-US" style="font-family: 'Times New Roman', serif;"><o:p></o:p></span></div>
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<span lang="EN-US" style="font-family: Georgia, serif;">-</span><span lang="EN-US" style="font-family: Georgia, serif;"> </span><i><span lang="EN-US" style="font-family: Georgia, serif;">S.boulardii</span></i><span lang="EN-US" style="font-family: Georgia, serif;"> </span><span lang="EN-US" style="font-family: Georgia, serif;">should be continued during
the transplant and 60 days afterwards.</span><span lang="EN-US" style="font-family: 'Times New Roman', serif;"><o:p></o:p></span></div>
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<span lang="EN-US" style="font-family: 'Times New Roman', serif;">1.<span style="font: normal normal normal 7pt/normal 'Times New Roman';"> </span></span><span lang="EN-US" style="font-family: Georgia, serif;">Add 50mL of stool (volume
occupied by solid stool) from the healthy donor immediately prior to
administration (< 30 minutes) to 200mL of normal saline in the blender.</span><span lang="EN-US" style="font-family: 'Times New Roman', serif;"><o:p></o:p></span></div>
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<span lang="EN-US" style="font-family: 'Times New Roman', serif;">2.<span style="font: normal normal normal 7pt/normal 'Times New Roman';"> </span></span><span lang="EN-US" style="font-family: Georgia, serif;">Mix until getting a
"milkshake" consistency.</span><span lang="EN-US" style="font-family: 'Times New Roman', serif;"><o:p></o:p></span></div>
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<span lang="EN-US" style="font-family: 'Times New Roman', serif;">3.<span style="font: normal normal normal 7pt/normal 'Times New Roman';"> </span></span><span lang="EN-US" style="font-family: Georgia, serif;">Pour mixture (approximately
250mL) into the enema bag.</span><span lang="EN-US" style="font-family: 'Times New Roman', serif;"><o:p></o:p></span></div>
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<span lang="EN-US" style="font-family: 'Times New Roman', serif;">4.<span style="font: normal normal normal 7pt/normal 'Times New Roman';"> </span></span><span lang="EN-US" style="font-family: Georgia, serif;">Administer enema to the
recipient following the kit instructions. The patient should hold the infusate
as long as possible and lie still as long as possible on his/her left side to
prevent the urge of defecation. The procedure should be ideally performed after
the first bowel movement.</span><span lang="EN-US" style="font-family: 'Times New Roman', serif;"><o:p></o:p></span></div>
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<span lang="EN-US" style="font-family: 'Times New Roman', serif;">5.<span style="font: normal normal normal 7pt/normal 'Times New Roman';"> </span></span><span lang="EN-US" style="font-family: Georgia, serif;">If diarrhea recurrs within
1 hour, the procedure may be immediately repeated.</span><span lang="EN-US" style="font-family: 'Times New Roman', serif;"><o:p></o:p></span></div>
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<u><span style="font-family: Georgia, serif;">Modifications and perspectives</span></u><span style="font-family: 'Times New Roman', serif;"><o:p></o:p></span></div>
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<u><span style="font-family: Georgia, serif;"><br /></span></u></div>
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<div style="text-align: justify;">
<span lang="EN-US" style="font-family: Georgia, serif;">This procedure was made to treat</span><span lang="EN-US" style="font-family: Georgia, serif;"> </span><i><span lang="EN-US" style="font-family: Georgia, serif;">C.difficile</span></i><span lang="EN-US" style="font-family: Georgia, serif;"> </span><span lang="EN-US" style="font-family: Georgia, serif;">infections. Accordingly,
the antibiotics and the probiotic used aimed to eliminate</span><span lang="EN-US" style="font-family: Georgia, serif;"> </span><i><span lang="EN-US" style="font-family: Georgia, serif;">C.difficile</span></i><span lang="EN-US" style="font-family: Georgia, serif;"> </span><span lang="EN-US" style="font-family: Georgia, serif;">from the gut. However,
there are certain modifications which can be useful for treating severe
dysbiosis. First, broad-spectrum antibiotics can be used to wash out most
bacterial species and reduce colonization resistance. In addition, utilization
of probiotics such as</span><span lang="EN-US" style="font-family: Georgia, serif;"> </span><i><span lang="EN-US" style="font-family: Georgia, serif;">Bifidobacteria</span></i><span lang="EN-US" style="font-family: Georgia, serif;"> </span><span lang="EN-US" style="font-family: Georgia, serif;">or</span><span lang="EN-US" style="font-family: Georgia, serif;"> </span><i><span lang="EN-US" style="font-family: Georgia, serif;">Lactobacilli</span></i><span lang="EN-US" style="font-family: Georgia, serif;"> </span><span lang="EN-US" style="font-family: Georgia, serif;">during and after the
treatment should help preventing colonization by enteropathogenic species. Why</span><span lang="EN-US" style="font-family: Georgia, serif;"> </span><i><span lang="EN-US" style="font-family: Georgia, serif;">Bifidobacteria</span></i><span lang="EN-US" style="font-family: Georgia, serif;">? The use of broad-spectrum
antibiotics increases the risk for colonization of enteropathogens.
Bifidobacteria competes and prevents colonization by these pathogens directly
and indirectly, via production of antibacterial molecules (</span><span style="font-family: Georgia, serif;"><a href="http://www.ncbi.nlm.nih.gov/pubmed/11034580/">2</a></span><span lang="EN-US" style="font-family: Georgia, serif;">). In addition, dysbiosis
is characterized by low levels and expression of Foxp3+ Tregs, which
compromises immune tolerance and promotes inflammation. Oral administration of</span><span lang="EN-US" style="font-family: Georgia, serif;"> </span><i><span lang="EN-US" style="font-family: Georgia, serif;">B.infantis</span></i><span lang="EN-US" style="font-family: Georgia, serif;"> </span><span lang="EN-US" style="font-family: Georgia, serif;">has been shown to increase
expression of Foxp3+ and IL-10 in peripheral blood and to drive maturation of
dendritic cells towards a regulatory phenotype (<a href="http://www.ncbi.nlm.nih.gov/pubmed/22052061">3</a>), and certain strains of Bifidobacteria are capable of modulating the plasticity of Th17/Treg populations in human PBMCs (<a href="http://www.ncbi.nlm.nih.gov/pubmed/21966367">4</a></span><span style="font-family: Georgia, serif;"><a href="http://www.ncbi.nlm.nih.gov/pubmed/22052061"></a></span><span lang="EN-US" style="font-family: Georgia, serif;">). On the other hand, Lactobacilli has also shown protective properties (specially against vaginal infections) (<a href="http://www.ncbi.nlm.nih.gov/pubmed/11909742">5</a>) and competes with enteropathogens for adhesion on intestinal epithelial cells (<a href="http://www.ncbi.nlm.nih.gov/pubmed/12972590">6</a>). Importantly, the effects over Treg induction and T cell differentiation differ between strains from the same species. I should address this issue in future posts. </span><span class="Apple-style-span" style="font-family: Georgia, serif; line-height: 20px;">One
thing that is not emphasized in the above protocol is the importance of diet
for maintaining a correct microbiota. This, in my opinion, is key to
success.</span><br />
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<span lang="EN-US"><o:p></o:p></span></div>
</div>
</div>
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<span style="font-family: Georgia, serif;"><br /></span></div>
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<span lang="EN-US" style="font-family: Georgia, serif;">It is worth noting that because of the nature of
the procedure, the microbiota of recipient subjects is altered and reduced, but
not completely eliminated such as seen with studies in fecal transplantation.
The utilization of fecal transplantation in humans is promising and should
result in better outcomes. Indeed, positive preliminary results from the
FATLOSE trial (</span><span style="font-family: Georgia, serif;"><a href="http://www.trialregister.nl/trialreg/admin/rctview.asp?TC=1776">7</a></span><span lang="EN-US" style="font-family: Georgia, serif;">,</span><span lang="EN-US" style="font-family: Georgia, serif;"> </span><span style="font-family: Georgia, serif;"><a href="http://www.trialregister.nl/trialreg/admin/rctview.asp?TC=2705">8</a></span><span lang="EN-US" style="font-family: Georgia, serif;">) have been recently
published in which patients with metabolic syndrome improved insulin resistance
and lipid profiles after feces infusion from healthy donors. The positive
results seem to be correlated with increases in colonic butyrate
concentrations. These results fit nicely with the ones found previously with
fecal transplantation in obese mice.</span><span lang="EN-US" style="font-family: 'Times New Roman', serif;"><o:p></o:p></span><br />
<span lang="EN-US" style="font-family: Georgia, serif;"><br /></span></div>
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<span lang="EN-US" style="font-family: Georgia, serif;">Turnbaugh et al (</span><span style="font-family: Georgia, serif;"><a href="http://www.ncbi.nlm.nih.gov/pubmed/17183312/">9</a></span><span lang="EN-US" style="font-family: Georgia, serif;">) found astonishing
differences in the microbiome of obese mice, compared to lean mice (greater
abundance of Firmicutes). Metagenomic analysis revealed that the obese
microbiome is enriched for EGT (environmental gene tags) encoding many enzymes
invoved in the break down of otherwise indigestable dietary polysaccharides.
These included KEGG pathways for starch/sucrose metabolism, galactose
metabolism and butanoate metabolism. Increased concentrations of butyrate and
acetate were also observed, as the fact that obese mice were able to harvest
more energy compared to lean mice (assessed by less energy remaining in feces
by bomb calorimetry,). Despite equal amount of food consumed in both groups,
colonization of lean mice with obese microbiota led to an increase in bodyfat
percentage of approximately 47% after two weeks. The potential for fecal bacteriotherapy in the treatment of several diseases has been observed in different animal models of inflammatory and autoimmune diseases.</span></div>
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<span lang="EN-US" style="font-family: Georgia, serif;"><br /></span></div>
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<span lang="EN-US" style="font-family: Georgia, serif;">Thus, it seems possible that future therapies for
obesity, metabolic syndrome and other inflammatory/autoimmune conditions will
aim to modulation of the gut microbiota.</span><span lang="EN-US" style="font-family: 'Times New Roman', serif;"><o:p></o:p></span></div>
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<br /></div>
<span style="float: left; padding: 5px;"><a href="http://www.researchblogging.org"><img alt="ResearchBlogging.org" src="http://www.researchblogging.org/public/citation_icons/rb2_large_white.png" style="border:0;"/></a></span><span class="Z3988" title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.jtitle=Clinical+gastroenterology+and+hepatology+%3A+the+official+clinical+practice+journal+of+the+American+Gastroenterological+Association&rft_id=info%3Apmid%2F20117243&rfr_id=info%3Asid%2Fresearchblogging.org&rft.atitle=Success+of+self-administered+home+fecal+transplantation+for+chronic+Clostridium+difficile+infection.&rft.issn=1542-3565&rft.date=2010&rft.volume=8&rft.issue=5&rft.spage=471&rft.epage=3&rft.artnum=&rft.au=Silverman+MS&rft.au=Davis+I&rft.au=Pillai+DR&rfe_dat=bpr3.included=1;bpr3.tags=Health%2CBiology%2C+Nutrition%2C+microbiology">Silverman MS, Davis I, & Pillai DR (2010). Success of self-administered home fecal transplantation for chronic Clostridium difficile infection. <span style="font-style: italic;">Clinical gastroenterology and hepatology : the official clinical practice journal of the American Gastroenterological Association, 8</span> (5), 471-3 PMID: <a rev="review" href="http://www.ncbi.nlm.nih.gov/pubmed/20117243">20117243</a></span>
Anonymousnoreply@blogger.com4tag:blogger.com,1999:blog-4724838399830873886.post-5267734608771661152011-11-08T21:51:00.001-08:002017-03-13T06:08:02.544-07:00Glucose restriction and TSC<div style="text-align: center; "><div style="text-align: justify; "><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif; ">Recently, </span><a href="http://twitter.com/#!/zooko" style="font-family: Georgia, 'Times New Roman', serif; ">zooko</a><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif; "> asked me about my opinion on a recent study just published (</span><a href="http://www.ncbi.nlm.nih.gov/pubmed/22018000" style="font-family: Georgia, 'Times New Roman', serif; ">1</a><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif; ">).</span></div></div><div style="text-align: justify; "><div><br /></div><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif; "><u><b>Background</b></u></span></div><div style="text-align: justify; "><div style="text-align: left; "><br /></div><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif; ">TSC1 and TSC2 are a pair of tumor supressor gene</span><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif; ">s, which relevance lies in the inhibition of mTORC1 activity. mTOR (the mammalian target </span><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif; ">of rapamycin) is a master regulator of cell proliferation, cell growth, cell motility, cell survival, protein synthesis and transcription. Because of this, dysregulation of the mTOR p</span><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif; ">athway is seen in many cancers (</span><a href="http://www.ncbi.nlm.nih.gov/pubmed/17613433" style="font-family: Georgia, 'Times New Roman', serif; ">2</a><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif; ">).</span></div><div style="text-align: justify; "><div style="text-align: left; "><br /></div><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif; ">mTOR forms two complexes, mTORC1 and mTORC2 ("rapamycin-insensitive"), which respond to different stimuli. </span>TSC2 has a GAP (GTPase activating protein) domain that stimulates the GTPase activity of Rheb. GDP-Rheb is inactive, while GTP-Rheb is active. By this mechanism, TSC2 accelerates the hydrolysis of GTP, inactivating Rheb. Active Rheb is a potent activator of mTORC1. The interplay between these proteins is shown below (<a href="http://www.ncbi.nlm.nih.gov/pubmed/17613433">3</a>):</div><div style="text-align: center; "><br /><img alt="" border="0" id="BLOGGER_PHOTO_ID_5672117445103881250" src="http://3.bp.blogspot.com/-AGlqYCIQb6Y/Trdow5-2jCI/AAAAAAAAABg/5lOEJqznAHc/s320/TSC.png" style="cursor: pointer; display: block; height: 230px; margin-bottom: 10px; margin-left: auto; margin-right: auto; margin-top: 0px; width: 320px; " /></div><div style="text-align: center; "><br /></div><div style="text-align: justify; ">In response to growth factors, Akt phosphorylates TSC2 directly on four or five residues (Ser939, Ser981, Ser1130, Ser1132 and Thr1462). Phosphorylation of TSC2 by Akt impairs its ability to inhibit Rheb, thereby blocking the inhibitory effect of Rheb on mTORC1. Other mechanisms proposed to explain contradictory experimental results include the action of PRAS40 and binding of 14-3-3 to phosphorylated TSC2.</div><div style="text-align: justify; "><br /></div><div style="text-align: justify; ">The most conserved pathway for Akt activation is the PI3K/Akt pathway. Insulin/IGF-1 binding to the insulin receptor produces phosphorylation of its cytosolic domain, promoting the binding of IRS (insulin receptor substrate) by its PTB (phosphotyrosine binding) domain. This promotes the association (by SH2 domains in the p85 regulatory subunit) and activation of PI3K. PI3K phosphorylates phosphatidylinositol-4,5-biphosphate (PtdIns(4,5)P2), producing PtdIns (3,4,5)P3. PtdIns (3,4,5)P3 binds to the PH domain of Akt and promotes its translocation to the plasma membrane. PI3K-dependent kinase 1 (PDK1) then phosphorylates Akt on Thr308 and PDK2 phosphorylates Ser473. Both phosphorylations activate Akt. Phosphorylated Akt, as previously mentioned, phosphorylates and inactivates TSC2 and PRAS40 promoting mTORC1 activation. The activation of the PI3K/Akt pathway has many downstream cellular events promoting cell survival and proliferation, which include inactivation of several proapoptotic factors (BAD, procaspase-9 and Forkhead transcription factors), activation of antiapoptotic factors (CREB), activation of IKK, inactivation of p53, among other. The net result is promoting proliferation and cell survival, hallmarks of cellular malignancy development and progression.</div><div style="text-align: justify; "><br /></div><div style="text-align: justify; "><u><b>Discussion of the study</b></u></div><div style="text-align: justify; "><br /></div><div style="text-align: justify; ">The basis for the utilization of glucose restriction for treating TSC related tumors can be easily inferred from the above explanation. By restricting glucose, insulin signaling is reduced, so is activation of mTORC1. mTORC1 also upregulates HIF1a, promoting aerobic glycolysis and lactate production (<a href="http://www.ncbi.nlm.nih.gov/pubmed/20670887">4</a>). Thus, glucose restriction should promote apoptosis, specially in TSC1/TSC2-null cells.</div><div style="text-align: justify; "><br /></div><div style="text-align: justify; ">What the authors basically did was treating Tsc2-/- mice with a carbohydrate-free diet (CF) and a Western Diet, alone or combined with <a href="http://en.wikipedia.org/wiki/2-Deoxy-D-glucose">2-deoxyglucose</a> (2-DG). Preliminary <i>in vitro</i> studies showed that Tsc2-/- cells were sensitive to glucose restriction and 2-DG in an additive manner. Contrary to what was expected, <i>in vivo</i> experiments showed that tumor size and growth rate were highest in the CF group and 2-DG supressed tumor growth independently of diet. These results also contradicted the observed standard uptake values (SUV) during the <a href="http://en.wikipedia.org/wiki/Fludeoxyglucose_(18F)">FDG-PET</a> scan (presented as the maximum SUV within each tumor). Theoretically, as these tumors are sensitive to glucose deprivation, there should be a correlation between glucose uptake (measured by uptake values of FDG) and tumor size (increased tumor size should show increased SUV). However, there was no correlation between these parameters, as the CF+2-DG group showed the minimum mean SUV but the largest tumor size. What can be fueling tumor growth? Ketone bodies? An <i>in vitro</i> assay showed that addition of either acetate or beta-hydroxybutyrate to Tsc2-/- cells increased <a href="http://en.wikipedia.org/wiki/Confluency">cell confluence</a> and reduced the number of non-viable cells (assessed by trypan blue), compared to glucose alone. To further complicate things, ketonemia was not developed in CF mice, but beta-hydroxybutyrate levels were higher with the Western +2-DG diet. Testing the effects of fatty acids <i>in vitro </i>showed that palmitic acid induced necrosis and oleic acid induced proliferation. This correlated with the histologic analysis of CF mice. Addition of rapamycin reduced cell-size, in contrast with 2-DG, which decreased proliferation. Finally, there was increased activation of mTORC1 (measured by phospho-S6) and low levels of phosphorylated Akt (secondary to feedback inhibition) in all groups, with no differences between groups.</div><div style="text-align: justify; "><br /></div><div style="text-align: justify; "><u>Interpretation</u></div><div style="text-align: justify; "><u><br /></u></div><div style="text-align: justify; ">First, the results confirm the potent anti-tumor activity of 2-DG. Second, the CF group failed to establish ketosis, and the Western group had increased levels of beta-hydroxybutyrate, as well as reduced tumor size. This (despite the observed growth-promoting properties of acetate and beta-hydroxybutyrate <i>in vitro</i>, see below) can be interpreted as an inhibitory effect of ketonemia on cancer growth. The comparison of glucose and beta-hydroxybutyrate levels is shown below:</div><div style="text-align: justify; "><br /></div><div style="text-align: center; "><a href="http://2.bp.blogspot.com/-O3xKKSfTRdU/Trn81lDwctI/AAAAAAAAABs/FYz6qnBA0N8/s1600/bOHB.png" style="text-align: left; " onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}"><img src="http://2.bp.blogspot.com/-O3xKKSfTRdU/Trn81lDwctI/AAAAAAAAABs/FYz6qnBA0N8/s320/bOHB.png" border="0" alt="" id="BLOGGER_PHOTO_ID_5672843203060986578" style="cursor: pointer; width: 320px; height: 170px; " /></a></div><div style="text-align: justify; "><br /></div><div style="text-align: justify; ">The diet which resulted in lower glucose levels and higher ketone bodies was associated with reduced tumor size, and the diet which produced greater glucose levels and lower ketone bodies was associated with increased tumor size. The results observed <i>in vitro</i> with Tsc2-/- cells and ketone bodies suggest that in this cell line, it is necessary an additional anti-glycolytic factor to control tumor growth (2-DG), because these (and other) cancer cells seem to be capable of metabolizing ketone bodies (<a href="http://www.ncbi.nlm.nih.gov/pubmed/20818174/">5</a>, <a href="http://www.ncbi.nlm.nih.gov/pubmed/21512313">6</a>). This underscores the importance of the phenotype of the tumor being treated, an important factor that is not taken into account by some "low-carb" advocates who think that restricting dietary glucose will magically cure all cancers.</div><div style="text-align: justify; "><br /></div><div style="text-align: justify; ">Another important factor to take into consideration is that mice were not calorie restricted, and more importantly, that the CF diet was high in protein. Glutamine is a major substrate that can fuel cancer cells (<a href="http://www.ncbi.nlm.nih.gov/pubmed/18032601/">7</a>, <a href="http://www.ncbi.nlm.nih.gov/pubmed/20086171">8</a>). On a more general level, aminoacids are potent stimulators of mTORC1 (<a href="http://www.ncbi.nlm.nih.gov/pubmed/18460336/">9</a>, <a href="http://www.ncbi.nlm.nih.gov/pubmed/18497260">10</a>). This is specially relevant for this model, because excess aminoacids can by-pass the inhibition of the PI3K/Akt pathway by promoting Rheb co-localization with mTORC1 (<a href="http://www.ncbi.nlm.nih.gov/pubmed/18765678">11</a>), activating mTORC1 in the abscence of TSC2 (<a href="http://www.ncbi.nlm.nih.gov/pubmed/19166931/">12</a>). Ketone bodies increased ATP levels in Tsc2-/-<i>in vitro</i>. This reduces AMPK activity. AMPK inhibits mTORC1 activity by TSC2 dependent and independent mechanisms (possibly by phosphorylation of Raptor) (<a href="http://www.ncbi.nlm.nih.gov/pubmed/18439900">12</a>). 2-DG also increases intracellular AMP levels (activating AMPK), which would explain the benefits of its utilization observed in this model (<a href="http://www.ncbi.nlm.nih.gov/pubmed/18247380">13</a>). Supporting the role of AMPK as a target for cancer treatment, the combination of metformin and 2-DG seems to be more toxic to cancer cells than either by itself (<a href="http://www.ncbi.nlm.nih.gov/pubmed/20559023">14</a>). Interestingly, AMPK activity was not changed in response to 2-DG in this model, which suggests that there are other mechanisms mediating the anti-proliferative effect of 2-DG.</div><div style="text-align: justify; "><br /></div><div style="text-align: justify; "><u>Summing up</u></div><div style="text-align: justify; "><u><br /></u></div><div style="text-align: justify; ">Cancer is a very complex disease which treatment has to be personalized depending on the phenotype. With the increase knowledge in cancer molecular biology and genetics, therapies should be designed depending on specific markers evaluated. This complexity explains why not all cancers can be treated just by restricting glucose and making such statement is ludicrous. Besides calorie, glucose and protein restriction, compounds such as 2-DG and metformin show promising effects for controlling most types of cancer.</div><div style="text-align: justify; "><br /></div><br /><br /><span style="float: left; padding-top: 5px; padding-right: 5px; padding-bottom: 5px; padding-left: 5px; "><a href="http://www.researchblogging.org/"><img alt="ResearchBlogging.org" src="http://www.researchblogging.org/public/citation_icons/rb2_large_white.png" style="border-top-width: 0px; border-right-width: 0px; border-bottom-width: 0px; border-left-width: 0px; border-style: initial; border-color: initial; " /></a></span><span class="Z3988" title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.jtitle=Cell+%26+bioscience&rft_id=info%3Apmid%2F22018000&rfr_id=info%3Asid%2Fresearchblogging.org&rft.atitle=Glucose+deprivation+in+Tuberous+Sclerosis+Complex-related+tumors.&rft.issn=&rft.date=2011&rft.volume=1&rft.issue=1&rft.spage=34&rft.epage=&rft.artnum=&rft.au=Jiang+X&rft.au=Kenerson+HL&rft.au=Yeung+RS&rfe_dat=bpr3.included=1;bpr3.tags=Health%2CBiology%2C+Nutrition%2C+Cancer%2C+Molecular+Biology">Jiang X, Kenerson HL, & Yeung RS (2011). Glucose deprivation in Tuberous Sclerosis Complex-related tumors. <span style="font-style: italic; ">Cell & bioscience, 1</span> (1) PMID: <a rev="review" href="http://www.ncbi.nlm.nih.gov/pubmed/22018000">22018000</a></span>Anonymousnoreply@blogger.com1tag:blogger.com,1999:blog-4724838399830873886.post-38321716411576453192011-10-31T13:00:00.000-07:002017-03-13T06:08:02.540-07:00Is phytate really a problem?<div style="text-align: justify;">
<span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;">As mentioned in a <a href="http://www.lucastafur.com/2011/10/rothia-to-rescue.html">previous post</a>, there is increasing evidence of adaptation to gluten consumption by humans. This adaptation is not genetic, but symbiotic. It appears that we have developed new symbiotic relationships with specific microorganisms to help us degrade gluten, and by doing so, being able to exploit an unnatural food source. </span></div>
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<span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;">Aside from resistance to degradation by mammalian enzymes and creation of neo-epitopes from partial gliadin digested peptides, one common reason given for avoiding gluten by paleo advocates is its phytate content (<a href="http://chriskresser.com/another-reason-you-shouldnt-go-nuts-on-nuts">1</a>, <a href="http://huntgatherlove.com/content/phytic-acid-taking-paleo-blinders">2</a>). Phytate is an anti-nutrient which binds to and form complexes with proteins, lipids, carbohydrates, and metal ions (zinc, iron, calcium and magnesium) thereby reducing their bioavailability. Phytate is the common name for myo-inositol-(1,2,3,4,5,6)-hexakiphosphate (InsP6). </span></div>
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<span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;">From its chemical structure, we can see that it is basically a <a href="http://en.wikipedia.org/wiki/Inositol">myo-inositol</a> with six phosphate groups. The ability to degrade InsP6 is conferred by phytases. There are three types of phytases, namely, 3-phytase, 5-phytase and 6-phytase. The differences between these phosphatases is the position on the inositol ring at which the initial attack of a phosphoester bond takes place. Thus, attack by different phytases produce different isomers. Phytase production and activity in humans is relatively low (mainly in the small intestine) (<a href="http://www.ncbi.nlm.nih.gov/pubmed/7959229/">3</a>), so the greatest source of phytases is the gut microbial community . </span><br />
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<span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;"><u>Gut flora phytase activity</u></span></div>
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<span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;">Of the <i>Bifidobacteria</i> species which predominate in the human gut, the <i>B. catenulatum</i> group (</span><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;"><i>B. catenulatum</i> </span><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;">and <i>B.pseudocatenulatum</i>) is the most common. Haros et al (<a href="http://www.ncbi.nlm.nih.gov/pubmed/19674804">4</a>) examined the InsP6 degrading capacity of <i>B.pseudocatenulatum</i> ATCC2919, isolated from the human gut. It was found that </span><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;"><i>B.pseudocatenulatum </i>is able to degrade InsP6 in sequential dephosphorylations (starting in the 6-position of the myo-inositol ring, followed by the 5-position). The solubility of mineral chelates of myo-inositol phosphates is related to the number of phosphates per molecule. InsP6 and InsP5 have adverse effects on mineral absorption. On the contrary, breakdown products with 1,2,3-grouping interact specifically with iron, increasing its solubility and preventing its ability to catalyse hydroxyl radical formation. Overall, the mineral-binding strength to inositol phosphates becomes progressively lower when phosphate are removed from the molecule (with the exception of the 1,2,3-grouping mentioned above). <i>B.pseudocatenulatum</i> also showed selective adhesion to <a href="http://en.wikipedia.org/wiki/Caco-2">Caco-2</a> epithelial cells and tolerance to increased concentrations of bile, which reflects its adaptation to the human gut. A previous study (<a href="http://www.ncbi.nlm.nih.gov/pubmed/17462768">5</a>) found that <i>B.infantis</i> is able to degrade 100% of InsP6, producing InsP3 as the main product. The optimal pH for the phytase activity of <i>B.infantis </i>was 6.0-6.5, with an activity of 51.2% at 37C; similar to that observed for </span><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;"><i>B.pseudocatenulatum</i>. Other <i>Bifidobacteria</i> species present in the human gut have also phytase activity, although to a lesser extent.</span><br />
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<span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;"><u>InsP6 antinutrient effect</u></span><br />
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<span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;">Typically, InsP6 and fiber occur together in whole foods. This is problematic for analyzing the antinutrient effect of InsP6 as there is evidence that fiber also reduces mineral bioavailability (<a href="http://www.ncbi.nlm.nih.gov/pubmed/1255269">6</a>). When given alone in animal models, InsP6 does not show toxic effects on bone minerals (<a href="http://www.ncbi.nlm.nih.gov/pubmed/14608114">7</a>):</span><br />
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<a href="http://4.bp.blogspot.com/-FsLH7CDmogk/Tq7I3BkXdwI/AAAAAAAAAKU/fVkGj9DWNHc/s1600/InsP6.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="171" src="http://4.bp.blogspot.com/-FsLH7CDmogk/Tq7I3BkXdwI/AAAAAAAAAKU/fVkGj9DWNHc/s320/InsP6.png" width="320" /></a></div>
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<span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;">This suggests that its the combination of fiber and InsP6 which causes the antinutrient effect observed. </span><br />
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<span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;">The type of fiber seems to be important on mineral bioavailability. The addition of <a href="http://en.wikipedia.org/wiki/Fructooligosaccharide">FOS</a> to a diet high in InsP6 improves cecal absorption of minerals and stimulates bacterial hydrolysis of InsP6 (<a href="http://www.ncbi.nlm.nih.gov/pubmed/11120448">8</a>, <a href="http://www.ncbi.nlm.nih.gov/pubmed/19665870">9</a>), counteracting the negative effects of high doses of InsP6. Inulin has also shown to improve calcium balance and absorption (<a href="http://www.ncbi.nlm.nih.gov/pubmed/9192195">10</a>). The importance of the fiber type on the effects of phytic acid is highlighted by a study in which healthy women following the recommended daily intake of fiber-rich wheat bread (300g/day) showed impaired iron status independent of the phytic acid content (<a href="http://www.ncbi.nlm.nih.gov/pubmed/15349738">11</a>).</span><br />
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<span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;"><u>Anti-cancer properties</u></span><br />
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<span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;">InsP6 is a broad-spectrum antioneoplastic agent <i>in vitro </i>and <i>in vivo</i> (<a href="http://www.ncbi.nlm.nih.gov/pubmed/14608114">12</a>). Structurally, InsP6 is similar to D-3-deoxy-3-fluoro-ptdIns, a potent PI3K inhibitor. Accordingly, InsP6 is able to inhibit PI3K and ERK phosphorylation (<a href="http://www.ncbi.nlm.nih.gov/pubmed/9230193">13</a>), thereby inhibiting AP-1 activation. InsP6 has also been shown to activate PKC delta and decrease phosphorylation of Erk1/Erk2 and Akt, causing upregulation of p27-Kip1 and reduction of pRb phosphorylation (<a href="http://www.ncbi.nlm.nih.gov/pubmed/15868430">14</a>). Other protective effects include the induction of apoptosis by inhibiting the Akt-NFkB pathway and increasing cytochrome C release (<a href="http://www.ncbi.nlm.nih.gov/pubmed/12507926">15</a>), downregulation of constitutive and ligand-induced mitogenic and cell survival signaling (showing different effects on ERK1/2, JNK1/2 and p38 in response to different mitogens) (<a href="http://www.ncbi.nlm.nih.gov/pubmed/19544333/">16</a>), its antioxidant effect (<a href="http://www.ncbi.nlm.nih.gov/pubmed/9034232">17</a>), enhancement of NK cell activity (<a href="http://www.ncbi.nlm.nih.gov/pubmed/2766453">18</a>), modulation of expression of TNF-alpha and its receptors genes (<a href="http://www.ncbi.nlm.nih.gov/pubmed/18536177">19</a>), inhibition of angiogenesis (<a href="http://www.ncbi.nlm.nih.gov/pubmed/15297368">20</a>) and metastasis, by modulation of integrin dimerization, cell surface expression and integrin-associated signaling pathway (lack of clustering of paxilin and reduced FAK autophosphorylation) (<a href="http://www.ncbi.nlm.nih.gov/pubmed/14666664">21</a>, <a href="http://www.ncbi.nlm.nih.gov/pubmed/14666663">22</a>). Utilization of </span><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;">InsP6 has been shown to offer some benefits during chemotherapy (<a href="http://www.ncbi.nlm.nih.gov/pubmed/20152024/">23</a>) and future trials are on their way.</span><br />
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<span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;"><u>Are whole grains inherently unhealthy?</u></span><br />
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<span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;">Because whole-grains and legumes are high in phytic acid, it is plausible to hypothesize that intake of these foods will reduce to some extent the risk of developing cancer. Whole-grain intake has been associated with reduced risk of cancers (<a href="http://www.ncbi.nlm.nih.gov/pubmed/9589426">24</a>, <a href="http://www.ncbi.nlm.nih.gov/pubmed/17881383">25</a>) as well as intake of legumes (<a href="http://www.ncbi.nlm.nih.gov/pubmed/10952096">26</a>). However, some studies have found no association (<a href="http://www.ncbi.nlm.nih.gov/pubmed/21656162">27</a>, <a href="http://www.ncbi.nlm.nih.gov/pubmed/14750535">28</a>). Because of the nature of these studies, it is not possible to draw causative conclusions. Most people eating the supposedly healthy foods have low intakes of harmful foods, so the decreased risk in some studies might be due to the exclusion and not the inclusion of some foods. In either case, most studies have not observed an increased cancer risk associated with these foods*. Other food sources rich in phytic acid include nuts and cocoa. </span><br />
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<span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;"><u>Conclusions</u></span><br />
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<span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;">The dangers of phytic acid have been overestimated. Contrary to popular the paleo belief, phytic acid might be beneficial in small doses and might have anticancer effects. As seen with gluten degradation by <i>Rothia</i> species, the phytase activity present in some exclusive human <i>Bifidobacteria</i> shows that adaptation to wheat/grains is indeed happening. Once again, the microbiota plays a dominant role.</span><br />
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<span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;">From epidemiological data, foods with high phytate content are not associated with increased risk for several chronic diseases. As association doesnt means causation, we cannot conclude that whole-grains are healthy but we cant also conclude that whole-grains are unhealthy. With the increasing attention to paleolithic and similar diets, it is of utmost importance that all evidence is critically analyzed and reviewed. Making unsupported statements and cherry-picking data would only cause rejection by scientists. Dogma is not good in science (or in anything else, for that matter).</span><br />
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<span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;">I dont recommend whole-grains and legumes because there are foods more nutritious, as well as because whole-grains and legumes are very high in carbohydrates. The potential benefits of phytate can be obtained by eating other phytate rich foods, such as nuts and cocoa; as well as soluble fiber and oligosaccharides as the main dietary fiber type. The problem with high levels of phytate is only relevant when the diet is deficient in micronutrients and essential food sources. Finally, maintaining a proper gut flora is essential for phytic acid metabolism and adequate mineral absorption. </span><br />
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<span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;">*Any evidence of a significant increased risk from these foods would be greatly appreciated.</span></div>
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<span style="float: left; padding-bottom: 5px; padding-left: 5px; padding-right: 5px; padding-top: 5px;"><a href="http://www.researchblogging.org/"><img alt="ResearchBlogging.org" src="http://www.researchblogging.org/public/citation_icons/rb2_large_white.png" style="border: 0;" /></a></span><span class="Z3988" title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.jtitle=International+journal+of+food+microbiology&rft_id=info%3Apmid%2F19674804&rfr_id=info%3Asid%2Fresearchblogging.org&rft.atitle=Phytate+degradation+by+human+gut+isolated+Bifidobacterium+pseudocatenulatum+ATCC27919+and+its+probiotic+potential.&rft.issn=0168-1605&rft.date=2009&rft.volume=135&rft.issue=1&rft.spage=7&rft.epage=14&rft.artnum=&rft.au=Haros+M&rft.au=Carlsson+NG&rft.au=Almgren+A&rft.au=Larsson-Alminger+M&rft.au=Sandberg+AS&rft.au=Andlid+T&rfe_dat=bpr3.included=1;bpr3.tags=Health%2CBiology%2C+Nutrition">Haros M, Carlsson NG, Almgren A, Larsson-Alminger M, Sandberg AS, & Andlid T (2009). Phytate degradation by human gut isolated Bifidobacterium pseudocatenulatum ATCC27919 and its probiotic potential. <span style="font-style: italic;">International journal of food microbiology, 135</span> (1), 7-14 PMID: <a href="http://www.ncbi.nlm.nih.gov/pubmed/19674804" rev="review">19674804</a></span><br />
<br />
<span class="Z3988" title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.jtitle=International+journal+of+food+microbiology&rft_id=info%3Apmid%2F17462768&rfr_id=info%3Asid%2Fresearchblogging.org&rft.atitle=Myo-inositol+hexakisphosphate+degradation+by+Bifidobacterium+infantis+ATCC+15697.&rft.issn=0168-1605&rft.date=2007&rft.volume=117&rft.issue=1&rft.spage=76&rft.epage=84&rft.artnum=&rft.au=Haros+M&rft.au=Bielecka+M&rft.au=Honke+J&rft.au=Sanz+Y&rfe_dat=bpr3.included=1;bpr3.tags=Health%2CBiology%2C+Nutrition">Haros M, Bielecka M, Honke J, & Sanz Y (2007). Myo-inositol hexakisphosphate degradation by Bifidobacterium infantis ATCC 15697. <span style="font-style: italic;">International journal of food microbiology, 117</span> (1), 76-84 PMID: <a href="http://www.ncbi.nlm.nih.gov/pubmed/17462768" rev="review">17462768</a></span>Unknownnoreply@blogger.com16tag:blogger.com,1999:blog-4724838399830873886.post-91519510794550521082011-10-27T11:28:00.000-07:002017-03-13T06:08:02.549-07:00Bifidobacteria, butyrate and carbohydrates<span class="Apple-style-span" style="font-family: Georgia,'Times New Roman',serif;">In a <a href="http://www.lucastafur.com/2011/10/food-and-antibiotic-resistance-genes.html">previous post</a>, john asked:</span><br />
<blockquote><span class="Apple-style-span" style="font-family: Georgia,'Times New Roman',serif;"><span class="Apple-style-span" style="background-color: white; line-height: 16px;">Regarding your old post on ketogenic diet and microbiota, why do you think bifidobacterium decreased on low carb? I would generally guess this is a negative...?</span></span></blockquote><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: Georgia,'Times New Roman',serif;">I cited two studies on low carbohydrate dieting and gut microbiota composition, one by Duncan et al (<a href="http://www.ncbi.nlm.nih.gov/pubmed/17189447?dopt=Abstract">1</a>) and the other by Brinkworth et al (<a href="http://www.ncbi.nlm.nih.gov/pubmed/19224658">2</a>). They showed a negative effect of reducing carbs on gut flora, measured by species composition (16S RNA) and SCFA. They both analyzed fecal samples. In general, fecal samples are reliable and make easier to study colonic SCFA metabolism. However, they are an indirect method of quantification. Of the three main SCFA produced in the colon, only acetate has shown a correlation between fecal concentration and absorption (<a href="http://www.ncbi.nlm.nih.gov/pubmed/14519799">3</a>):</span><br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://jn.nutrition.org/content/133/10/3145/F2.medium.gif" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="212" src="http://jn.nutrition.org/content/133/10/3145/F2.medium.gif" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Copyright © 2011 by the American Society for Nutrition</td></tr>
</tbody></table><span class="Apple-style-span" style="font-family: Georgia,'Times New Roman',serif;"><br />
</span><br />
<span class="Apple-style-span" style="font-family: Georgia,'Times New Roman',serif;">The data shows a negative correlation (r=-0.834) between acetate absorption from an infusion and fecal acetate concentration. This means that the fecal concentration of acetate might reflect absorption rather than production, in an inverse manner (less acetate in fecal samples equals more absorption). In this study, neither propionate or butyrate showed a correlation between absorption and fecal concentration. </span><br />
<br />
<span class="Apple-style-span" style="font-family: Georgia,'Times New Roman',serif;"><u>SCFA in the Duncan et al. study</u></span><br />
<br />
<span class="Apple-style-span" style="font-family: Georgia,'Times New Roman',serif;">Acetate, butyrate and propionate concentrations in fecal samples from the Duncan et al. study are shown below:</span><br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://2.bp.blogspot.com/-z1MfBRD6rCo/TqMWZOdGaZI/AAAAAAAAAHM/zIrS6JRxVyw/s1600/SCFA+duncan.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" src="http://2.bp.blogspot.com/-z1MfBRD6rCo/TqMWZOdGaZI/AAAAAAAAAHM/zIrS6JRxVyw/s1600/SCFA+duncan.png" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">SCFA concentrations (mM) for fecal samples. M=Maintenace; HPMC= High-protein, moderate-carbohydrate; HPLC = High-protein, low-carbohydrate. Mean values.</td></tr>
</tbody></table><br />
<span class="Apple-style-span" style="font-family: Georgia,'Times New Roman',serif;">As the intake of carbohydrate decreased, there was a parallel reduction in all three SCFA. </span><br />
<br />
<span class="Apple-style-span" style="font-family: Georgia,'Times New Roman',serif;"><u>SCFA in the Brinkworth et al. study</u></span><br />
<br />
<span class="Apple-style-span" style="font-family: Georgia,'Times New Roman',serif;">Acetate, butyrate and propionate concentrations in fecal samples from the Brinkworth et al. study are shown below:</span><br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://4.bp.blogspot.com/-7xuPdj5MKFI/TqMb3vr5c_I/AAAAAAAAAHU/YnTsMJsWlPY/s1600/SCFA+brinkworth.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" src="http://4.bp.blogspot.com/-7xuPdj5MKFI/TqMb3vr5c_I/AAAAAAAAAHU/YnTsMJsWlPY/s1600/SCFA+brinkworth.png" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Fecal SCFA concentrations (mM) after 8 weeks of either a low carbohydrate (LC) or high carbohydrate (HC) diet. Mean values. </td></tr>
</tbody></table><br />
<span class="Apple-style-span" style="font-family: Georgia,'Times New Roman',serif;">As seen in the Duncan et al. study, after 8 weeks with a low-carbohydrate diet, SCFA concentrations were reduced, although not as drastically. </span><br />
<br />
<span class="Apple-style-span" style="font-family: Georgia,'Times New Roman',serif;"><u><b>Analysis and interpretation of the data</b></u></span><br />
<br />
<span class="Apple-style-span" style="font-family: Georgia,'Times New Roman',serif;">Both studies show a clear correlation between carbohydrate intake and SCFA concentration in fecal samples. The magnitude of the changes between individual SCFA might be due to differences in the intervention time (4 weeks vs. 8 weeks). </span><br />
<br />
<span class="Apple-style-span" style="font-family: Georgia,'Times New Roman',serif;">As shown by Vogt and Wolever (see above), acetate concentration in fecal samples reflect more precisely acetate absorption rather than production. Thus, lower fecal acetate levels with reduced carbohydrate reflect more acetate absorption (or utilization, see below). </span><br />
<br />
<span class="Apple-style-span" style="font-family: Georgia,'Times New Roman',serif;">Most focus has been given to the apparent reduction in butyrate levels, which may compromise colonic health. In this regard, low carbohydrate diets might be detrimental for colonic health because of reduced butyrate production. For assessing the validity of this statement, we must look at colonic butyrate metabolism. </span><br />
<br />
<span class="Apple-style-span" style="font-family: Georgia,'Times New Roman',serif;"><u>Colonic butyrate metabolism </u></span><br />
<br />
<span class="Apple-style-span" style="font-family: Georgia,'Times New Roman',serif;">Approximately, 95% of the butyrate produced in the colon is absorbed. This is why fecal concentrations are not a good guide to production rates: a very high proportion of the SCFA is taken up by the colonic mucosa (<a href="http://www.ncbi.nlm.nih.gov/pubmed/12480096">4</a>). Butyrate is produced from two molecules of acetyl CoA, yielding acetoacetyl CoA, which is further converted to finally butyryl CoA. This metabolite can be converted to butyrate via butyrate kinase or butyryl CoA:acetate CoA transferase.</span><br />
<br />
<span class="Apple-style-span" style="font-family: Georgia,'Times New Roman',serif;">Butyrogenic substrates include starch, inulin and xylan. But certain species are capable of producing butyrate from acetate. Synthesis of butyrate from acetate is performed via the butyryl CoA:acetate CoA transferase pathway, which seems to be the most prevalent route of butyrate synthesis by human gut bacteria (<a href="http://www.ncbi.nlm.nih.gov/pubmed/15028695">5</a>). So, while glucose is needed for butyrate synthesis, acetate seems to be the main substrate for butyrate formation. The predominance of butyrate synthesis from the acetate dependent pathway might reflect a selective advantage for bacteria which transform acetate to butyrate in the colon, where acetate concentrations are high. </span><br />
<br />
<span class="Apple-style-span" style="font-family: Georgia,'Times New Roman',serif;">Overall, the reduction in acetate and butyrate fecal concentrations may be translated to increased absorption and reduced excretion. Butyrate can be synthesized from acetate, which reduces the concentration of both SCFA in feces. The determined Km for butyrate transport in the colon has been found to be 14.8 +/-3.6 mM (<a href="http://www.ncbi.nlm.nih.gov/pubmed/9508842">6</a>) and 17.5 +/- 4.5 mM in the proximal colon (<a href="http://www.ncbi.nlm.nih.gov/pubmed/11897627">7</a>). The apparent saturation kinetics showed by butyrate transport across the colonic luminal membrane could further explain the results seen in the studies mentioned above: increasing the carbohydrate content in the diet would augment the number of glucose-dependent butyrogenic bacteria, increasing the colonic production and concentration of butyrate. Because transport of butyrate is saturable, excess butyrate is excreted, producing increased levels in feces. </span><br />
<br />
<span class="Apple-style-span" style="font-family: Georgia,'Times New Roman',serif;"><u>The case for <i>Bifidobacteria</i></u></span><br />
<br />
<span class="Apple-style-span" style="font-family: Georgia,'Times New Roman',serif;">The change in <i>Bifidobacteria</i> concentrations after the low carbohydrate diet is due to the presence of an important number of bacteria capable of degrading glucose/starch. In this scenario, reduced carbohydrate availability would reduce the number of total <i>Bifidobacteria</i> (at least certain species). This does not mean that this is bad <i>per se.</i> It is important to determine the specific <i>Bifidobacteria</i> which are responsive to diet. For instance, <i>B.longum</i> seem to be capable of catabolizing not only dietary oligosaccharides, but also glycoproteins and glycoconjugates from the host; as well as nucleotides (<a href="http://www.ncbi.nlm.nih.gov/pubmed/12381787">8</a>). Moreover, gut <i>Bifidobacteria</i> (as shown by the genomic analysis of <i>B.longum</i>), are capable of adapting to different carbohydrate substrates depending on their availability (<a href="http://www.ncbi.nlm.nih.gov/pubmed/14503691">9</a>). In addition, metabolic-crossfeeding occurs between <i>Bifidobacteria</i> and other species. For example, <i>E.hallii</i>, a butyrogenic bacterium, is unable to grow on pure starch by itself. Co-culture of this bacterium with <i>B.adolescentis </i>stimulates its growth and butyrate synthesis, paralleled by a reduction in lactate levels (<a href="http://www.ncbi.nlm.nih.gov/pubmed/16672507">10</a>). The scheme is pretty simple: <i>B.adolescentis</i> is capable of fermenting starch, producing lactate which serves as substrate to <i>E.hallii</i>. Other lactate-independent mechanisms of cross-feeding have also been observed in FOS and oligofructose-only co-cultures of <i>B.longum</i> with <i>Roseburia intestinalis</i> or <i>Anaerostipes caccae</i>, which are cabaple of producing butyrate and consuming acetate (<a href="http://www.ncbi.nlm.nih.gov/pubmed/17056678">11</a>).</span><br />
<br />
<span class="Apple-style-span" style="font-family: Georgia,'Times New Roman',serif;">Because of its complexity, the specific mechanisms by which certain <i>Bifidobacteria</i> could be beneficial are unknown, although there is evidence of health benefits from increasing gut <i>Bifidobacteria</i> (<a href="http://www.ncbi.nlm.nih.gov/pubmed/17823788/">12</a>, <a href="http://www.ncbi.nlm.nih.gov/pubmed/21685239">13</a>, <a href="http://www.ncbi.nlm.nih.gov/pubmed/21914236">14</a>). There are some issues with interpreting the evidence in this topic:</span><br />
<br />
<ul><li><span class="Apple-style-span" style="font-family: Georgia,'Times New Roman',serif;"> Many authors don't determine the exact species being studied (take all <i>Bifidobacteria</i> as a group). </span></li>
<li><span class="Apple-style-span" style="font-family: Georgia,'Times New Roman',serif;">Supplementation is done with different strains and the long-term effects are not known, because bacteria supplemented via diet are treated as allochthonous. </span></li>
<li><span class="Apple-style-span" style="font-family: Georgia,'Times New Roman',serif;">Genomic inspection has shown that <i>Bifidobacteria</i> are metabolically very flexible. Adaptation to substrate variations might take longer than 8 weeks. </span></li>
<li><span class="Apple-style-span" style="font-family: Georgia,'Times New Roman',serif;">There is metabolic-crossfeeding occuring between bacteria. This is a highly complex network of connections for which we are only starting to get an initial picture. </span></li>
</ul><br />
<span class="Apple-style-span" style="font-family: Georgia,'Times New Roman',serif;">Having this in mind, I cant assure either that a low carbohydrate diet is not harmful to the gut microbiota. As far as the evidence goes, we can only speculate and formulate hypotheses. And useful hypotheses should be based on logic and evolutionary inference. We should ask not only "how" but also "why". In this case, we are not going to focus on the "how" but on the "why"; to put it formally, why an increased intake of starch is associated with an increase in <i>Bifidobacteria</i>? What is the evolutionary basis?</span><br />
<br />
<span class="Apple-style-span" style="font-family: Georgia,'Times New Roman',serif;">One important protective role of <i>Bifidobacteria</i> is preventing colonization of enteropathogens by reducing their adhesion to intestinal epithelial cells. This has been shown directly for <i>E. coli</i> and <i>S. typhimurium</i> (<a href="http://www.ncbi.nlm.nih.gov/pubmed/18524406">15</a>). Other commonly problematic Enterobacteriaceae include <i>Klebsiella</i> and <i>Shigella</i>. Growth of these pathogens is stimulated by high glucose-low oxygen conditions. The selective advantage of having responsive <i>Bifidobacteria</i> in the gut might be protection. As increased glucose concentrations favor the development of an adequate environment for growth of these pathogens, there has to be a mechanism by which the composition of the normal microbiota is maintained. So there is a parallel increase in <i>Bifidobacteria</i> with increasing concentrations of dietary carbohydrates to restrain colonization of pathogenic anaerobes. The fact that certain species of <i>Bifidobacteria </i>can metabolize different oligosaccharides and adapt to the substrate availability supports this hypothesis. I might elaborate more on this in subsequent posts. </span><br />
<br />
<span class="Apple-style-span" style="font-family: Georgia,'Times New Roman',serif;"><u><b>Conclusions</b></u></span><br />
<br />
<span class="Apple-style-span" style="font-family: Georgia,'Times New Roman',serif;">Low carbohydrate diets seem to reduce the fecal concentration of SCFA in the short term. Some adaptation seems to occur, judging by the differences between the study periods (4 weeks vs. 8 weeks). Fecal concentrations of SCFA are not good indicators of SCFA colonic production. Conversely, they rather reflect excretion (butyrate) and absorption (acetate). Butyrate can be produced from different substrates, of which acetate is the main precursor in the human gut. There is a reduction in the levels of <i>Bifidobacteria</i> detected in stool samples, proportional to the decrease in carbohydrate in the diet. Although no individual species where identified, studies have shown that <i>Bifidobacteria</i> are capable of adapting to substrate availability and cross-feed with other bacteria. The evolutionary basis for increased <i>Bifidobacteria</i> in response to sugar might involve a protective mechanism against colonization of enteropathogenic bacteria, such as <i>E. coli</i>, <i>Klebsiella</i>, <i>Shigella</i> and <i>Salmonella</i>. </span><br />
<br />
<span style="float: left; padding: 5px;"><a href="http://www.researchblogging.org/"><img alt="ResearchBlogging.org" src="http://www.researchblogging.org/public/citation_icons/rb2_large_white.png" style="border: 0;" /></a></span><span class="Z3988" title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.jtitle=Applied+and+environmental+microbiology&rft_id=info%3Apmid%2F17189447&rfr_id=info%3Asid%2Fresearchblogging.org&rft.atitle=Reduced+dietary+intake+of+carbohydrates+by+obese+subjects+results+in+decreased+concentrations+of+butyrate+and+butyrate-producing+bacteria+in+feces.&rft.issn=0099-2240&rft.date=2007&rft.volume=73&rft.issue=4&rft.spage=1073&rft.epage=8&rft.artnum=&rft.au=Duncan+SH&rft.au=Belenguer+A&rft.au=Holtrop+G&rft.au=Johnstone+AM&rft.au=Flint+HJ&rft.au=Lobley+GE&rfe_dat=bpr3.included=1;bpr3.tags=Health%2CBiology%2C+Nutrition">Duncan SH, Belenguer A, Holtrop G, Johnstone AM, Flint HJ, & Lobley GE (2007). Reduced dietary intake of carbohydrates by obese subjects results in decreased concentrations of butyrate and butyrate-producing bacteria in feces. <span style="font-style: italic;">Applied and environmental microbiology, 73</span> (4), 1073-8 PMID: <a href="http://www.ncbi.nlm.nih.gov/pubmed/17189447" rev="review">17189447</a></span><br />
<br />
<span class="Z3988" title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.jtitle=The+British+journal+of+nutrition&rft_id=info%3Apmid%2F19224658&rfr_id=info%3Asid%2Fresearchblogging.org&rft.atitle=Comparative+effects+of+very+low-carbohydrate%2C+high-fat+and+high-carbohydrate%2C+low-fat+weight-loss+diets+on+bowel+habit+and+faecal+short-chain+fatty+acids+and+bacterial+populations.&rft.issn=0007-1145&rft.date=2009&rft.volume=101&rft.issue=10&rft.spage=1493&rft.epage=502&rft.artnum=&rft.au=Brinkworth+GD&rft.au=Noakes+M&rft.au=Clifton+PM&rft.au=Bird+AR&rfe_dat=bpr3.included=1;bpr3.tags=Health%2CBiology%2C+Nutrition">Brinkworth GD, Noakes M, Clifton PM, & Bird AR (2009). Comparative effects of very low-carbohydrate, high-fat and high-carbohydrate, low-fat weight-loss diets on bowel habit and faecal short-chain fatty acids and bacterial populations. <span style="font-style: italic;">The British journal of nutrition, 101</span> (10), 1493-502 PMID: <a href="http://www.ncbi.nlm.nih.gov/pubmed/19224658" rev="review">19224658</a></span></div>Unknownnoreply@blogger.com12tag:blogger.com,1999:blog-4724838399830873886.post-87791282799440738982011-10-21T23:02:00.000-07:002017-03-13T06:08:02.547-07:00Rothia to the rescue<div style="text-align: justify;"><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;">Gluten is problematic. Almost every paleo advocate agrees that wheat should be restricted in the diet because gliadin peptides generated by the uncomplete digestion of gluten produces highly reactive epitopes, which then can trigger a T-cell response in the gut. </span></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;"><br />
</span></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;">The main issue with the "gluten is bad for everyone" meme is that not all people develop gluten sensitivity or celiac disease. Many can tolerate great doses of wheat-based foods for years without serious health consequences. This is often attributed to lack of an environmental trigger which increases susceptibility to gliadin peptides (ie. inflammation). </span></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;"><br />
</span></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;">A recent paper (<a href="http://www.ncbi.nlm.nih.gov/pubmed/21957450">1</a>) has found that two strains from the genus <i>Rothia</i>, namely <i>R.mucilaginosa</i> and <i>R. aeria</i> are capable of metabolizing gluten. These are oral microorganisms.</span></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;"><br />
</span></div><div class="separator" style="clear: both; text-align: center;"></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;">After isolation on a gluten agar media, these microbes were capable of hydrolizing YPQ tripeptides (which occur with high frequency in gluten sequences) and KPQ. Moreover, <i>R.aeria</i> degraded gliadin <i>in vitro</i>: </span></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;"><br />
</span></div><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://4.bp.blogspot.com/-s3Gej4MDUdw/TqJE3S6mnWI/AAAAAAAAAG8/kX1wfdg89yw/s1600/SDSPAGE.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="175" src="http://4.bp.blogspot.com/-s3Gej4MDUdw/TqJE3S6mnWI/AAAAAAAAAG8/kX1wfdg89yw/s400/SDSPAGE.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">SDS-PAGE of aliquots from the incubation mixture</td></tr>
</tbody></table><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;">The arrow shows the major protein constitutent in the gliadin mixture. As it can be seen, gliadin was progressively degrated (lanes 2-7, figure A). Shorter time intervals (lanes 2-7, figure B) show that almost 50% of gliadin was degraded in 30 minutes. Boiling bacterial suspensions abolished degradation (lanes 8 and 9, figure B). This suggests enzyme denaturation. Lanes 10-11 and 12-13 served as negative and positive controls, respectively. </span></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;"><br />
</span></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;">Proteolytic degradation of two problematic peptides (a-gliadin derived 33-mer and y-gliadin derived 26-mer) was compared between mammalian enzymes (pepsin, trypsin, chymotrypsin) and </span><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;"><i>R.aeria</i>:</span></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;"><br />
</span></div><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://4.bp.blogspot.com/-Z02H-Cbd0BA/TqJJZUJ4p3I/AAAAAAAAAHE/Zg6luG06uSU/s1600/RPHPLC.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="225" src="http://4.bp.blogspot.com/-Z02H-Cbd0BA/TqJJZUJ4p3I/AAAAAAAAAHE/Zg6luG06uSU/s400/RPHPLC.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">RP-HPLC of sample aliquots</td></tr>
</tbody></table><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;">As it can be seen, chromatograms from all mammalian enzymes show the same pattern at 0 and 24h, showing no digestion of the peptides (A-C). In contrast, the sample containing <i>R.aeria</i> (WSA-8, figure D) showed the presence of different peaks earlier in the chromatogram, representing degradation fragments which elute earlier. At 2 hours, the peptide was completely degraded. </span></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;"><br />
</span></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;">These results show that enzymes present in <i>R.aeria </i>are capable of degrading gliadin and two peptides (33-mer and 26-mer) which are resistant to mammalian enzymes. Analysis by Mass Spectrometry determined that cleavage was made after QPQ and LPY for <i>R. aeria</i> and XPQ and LPY for <i>R.mucilaginosa </i>(X denotes any aminoacid). This is important because these tripeptides are part of the immunogenic epitopes contained within the 33-mer (glia-a9, glia-a2) and 26-mer peptides (glia-y2):</span></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;"><br />
</span></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;">glia-a9: LQLQPFP<u>QPQLPY</u></span></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;">glia-a2: P<u>QPQLPYPQP</u>Q<u>LPY</u></span></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;">glia-y2: P<u>FPQQPQ</u>QP / P<u>YPQQPQ</u>QP</span></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;"><br />
</span></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;">It is worth noting that cleavage from both <i>Rothia</i> strains was observed also after Q residues along the 26-mer sequence. Repeated Q residues (along with P residues) are responsible for resistance to proteolysis by mammalian enzymes. </span></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;"><br />
</span></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;">Zymography at pH 7.0 showed that the putative gliadin-degrading enzymes had a molecular weight of approximately 75kDa and 70kDa for <i>R.mucilaginosa</i> and <i>R.aeria</i>, respectively. Further analysis on the activity of these enzymes at different pH revealed that enzymes from <i>R.mucilaginosa</i> were completely inactive at pH 3.0, while <i>R.aeria</i> maintained a weak enzymatic activity. The optimal pH determined was 7.0, and substrate hydrolysis rates declined in parallel with decreasing pH values from 7.0 to 4.0. At pH 3.0, <i>R.aeria </i>showed a much slower activity, while at pH 2.0, activity was completely abolished. </span></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;"><br />
</span></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;"><u>Summary</u></span></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;"><u><br />
</u></span></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;">- </span><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;"><i>R.mucilaginosa</i> and <i>R.aeria </i>were capable of degrading gliadin and immunogenic peptides <i>in vitro</i>.</span></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;">- The enzymes present have an approximate molecular weight of 70-75kDa. </span></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;">- Degrading activity of </span><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;"><i>R.aeria </i>was maintained at pH 3.0. </span></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;">- Both species are normal colonizers of the oral cavity and other areas (</span><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;"><i>R.mucilaginosa</i></span><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;">).</span></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;"><br />
</span></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;">From the discussion (my bolds):</span></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;"><br />
</span></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;">"</span><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;">R. aeria (...)</span><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;"> is an </span><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;">oral colonizer [31]. R. mucilaginosa also primarily colonizes the oral </span><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;">cavity [33] but has furthermore been isolated from other body </span><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;">sites, including the upper respiratory tract and the duodenum [34,35,36]"</span></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;"><br />
</span></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;">"</span><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;">Bacterial speciation of 2,247 clones recovered from </span><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;">63 duodenal biopsies obtained from healthy and celiac patients </span><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;">showed that <b>R. mucilaginosa comprised [aprox.] 6% of the clones and was </b></span><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;"><b>present in [aprox.] 65% of the biopsies, identifying it as a true colonizer </b></span><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;"><b>of the duodenum</b> [36]."</span></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;"><br />
</span></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;">The million dollar question:</span></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;"><br />
</span></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;">"</span><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;">The discovery of salivary microorganisms degrading dietary </span><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;">proteins in vitro prompts the question <b>to what extent such </b></span><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;"><b>microorganisms play a role in food processing in vivo</b>. During </span><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;">mastication (chewing) foods are mixed with whole saliva helping to </span><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;">accelerate the break-down by digestive enzymes during the </span><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;">residency time in the oral cavity. Oral microorganisms in the </span><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;">swallowed food bolus may or may not survive and/or continue to </span><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;">exert proteolytic activities during or after gastric passage. <b>Our in </b></span><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif; font-weight: bold;">vitro data with R. aeria show that its enzymes are not abolished at </span><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif; font-weight: bold;">acidic pH values, and are optimally active under more basic pH </span><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif; font-weight: bold;">conditions. <span class="Apple-style-span" style="color: red;">In vivo, this could mean that during gastric passage the </span></span><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif; font-weight: bold;"><span class="Apple-style-span" style="color: red;">enzymes will neither be active nor destroyed, and that enzymatic </span></span><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;"><b><span class="Apple-style-span" style="color: red;">reactivation would occur upon transfer to the duodenum</span>.</b></span></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;"><br />
</span></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;">With </span><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;">regard to duodenal Rothia enzyme activity, it is relevant that R. </span><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;">mucilaginosa gains a foothold in the duodenum [36]. <b>This offers the </b></span><b><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;">intriguing possibility that Rothia may colonize the duodenum and </span><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;">perform proteolytic activities locally in conjunction with mammalian- </span><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;">derived enzymes to degrade gluten.</span></b><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;">"</span></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;"><br />
</span></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;">The study here presented is a follow-up of one published in 2010 by the same group (<a href="http://www.ncbi.nlm.nih.gov/pubmed/20948997">2</a>) in which they found that oral bacteria were capable of degrading completely immunogenic gliadin peptides. </span></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;"><br />
</span></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;">Further studies should help elucidate detailed information about the enzymes responsible for gluten degradation by these bacteria. </span></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;"><br />
</span></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;">This relationship might offer a way in which we are evolving and adapting to foods introduced in the neolithic: not only by changes in genes and gene expression (ie. <i>AMY1</i>), but also by establishing new symbiotic relationships with microorganisms. </span></div><br />
<span style="float: left; padding: 5px;"><a href="http://www.researchblogging.org"><img alt="ResearchBlogging.org" src="http://www.researchblogging.org/public/citation_icons/rb2_large_gray.png" style="border:0;"/></a></span><span class="Z3988" title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.jtitle=PloS+one&rft_id=info%3Apmid%2F21957450&rfr_id=info%3Asid%2Fresearchblogging.org&rft.atitle=Identification+of+rothia+bacteria+as+gluten-degrading+natural+colonizers+of+the+upper+gastro-intestinal+tract.&rft.issn=&rft.date=2011&rft.volume=6&rft.issue=9&rft.spage=&rft.epage=&rft.artnum=&rft.au=Zamakhchari+M&rft.au=Wei+G&rft.au=Dewhirst+F&rft.au=Lee+J&rft.au=Schuppan+D&rft.au=Oppenheim+FG&rft.au=Helmerhorst+EJ&rfe_dat=bpr3.included=1;bpr3.tags=Biology%2CNutrition%2C+Immunology%2C+Molecular+Biology%2C+Microbiology">Zamakhchari M, Wei G, Dewhirst F, Lee J, Schuppan D, Oppenheim FG, & Helmerhorst EJ (2011). Identification of rothia bacteria as gluten-degrading natural colonizers of the upper gastro-intestinal tract. <span style="font-style: italic;">PloS one, 6</span> (9) PMID: <a rev="review" href="http://www.ncbi.nlm.nih.gov/pubmed/21957450">21957450</a></span>Unknownnoreply@blogger.com10tag:blogger.com,1999:blog-4724838399830873886.post-30087521832306288092011-10-11T14:29:00.000-07:002017-03-13T06:08:02.531-07:00Food and antibiotic resistance genes<div style="text-align: justify;"><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;">Antibiotic resistance (AR) and horizontal transmission of resistance genes is a major health problem in the modern world. Antibiotic abuse and dysbiosis seem to be the main causes, but an interesting potential source of these genes is just being explored. I came across a paper which analyzed the level of AR genes in common retail foods (<a href="http://www.ncbi.nlm.nih.gov/pubmed/16445749">1</a>). </span></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;"><br />
</span></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;">The specific markers examined were <i>ermB</i>, <i>ermC</i>, <i>tet</i>S/M and <i>tet</i>A, which encode ribosomal modification and tetracycline (Tet) efflux mechanisms. Foods analyzed included different kinds of cheese (Cheddar, Swiss, Colby, Mozzarella), yogurt, raw milk, shrimp, pork chop, deli turkey, deli beef, mushroom and spinach. They found AR microbes in nearly all samples, either from raw or ready-to-eat foods. The only foods which showed no detectable AR microbes were processed cheese (heat treated during manufacture) and yogurt. 20 of the 23 cheese samples contained Tetr and/or Emr* (tetracycline and erythromycin resistance genes, respectively), and the number of Tetr microbes was greater than that of Emr in this food. </span></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;"><br />
</span></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;">The presence of selected AR genes from cheese and milk was analyzed by conventional PCR. It was found that:</span></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;"><br />
</span></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;">- Among Tetr isolates recovered from cheese, about 10% contained the <i>tet</i>S/M gene. 7 out of 11 <i>tet</i>S/M+ were <i>Staphylococcus thermophilus</i> and two isolates were <i>Lactococcus lactis</i>. Two additional isolates had 97% 16S rRNA gene sequence identity to unidentified <i>Lactococcus</i> sp. and 93-94% identity to <i>Lactococcus garvieae</i> and <i>Lactococcus lactis</i>, similar to an isolate from milk. This suggests that <i>Lactococcus</i> might be a common organism from milk. Another </span><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;"><i>tet</i>S/M+ isolate from raw milk was identified as <i>Leuconostoc</i> sp. Two isolates from cheese presented the <i>tet</i>A gene, as well as several isolates from raw pork meat; and were identified as <i>Pseudomonas</i> sp. </span></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;"><br />
</span></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;">- Among Emr isolates from cheese, more than 50% had the <i>erm</i>B gene. The carrier organisms identified were <i>Staphylococcus</i> sp. (5 out of 28) and <i>S. thermophilus</i> ( 23 out of 28). One isolate, characterized as <i>Pseudomonas</i> sp., from packaged sliced chicken lunchmeat contained the <i>erm</i>C and <i>tet</i>S/M genes, suggesting a multidrug resistance phenotype. </span></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;"><br />
</span></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;"><a href="http://en.wikipedia.org/wiki/Minimum_inhibitory_concentration">MIC</a> analysis showed resistance to tetracycline, erythromycin, clarithromycin and clindamycin in several isolates, some of them showing multidrug resistance.</span></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;"><br />
</span></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;">Because of the importance of horizontal gene transfer of AR genes to the human microbiota, the authors tested the potential transfer between some strains identified to resident oral bacteria. They used <i>Staphylococcus mutans</i> as recipient, which is a cariogenic oral pathogen. The plasmid (20-25kb) isolated from bacteria from food samples was succesfully transferred to S. mutans, confirmed by PCR amplification. MIC test showed that the transformed S. mutans had significantly increased resistance to tetracycline compared with the parental strain. </span></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;"><br />
</span></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;">The presence of AR genes in other foods and the horizontal transfer of resistance genes to the human microbiota has been confirmed in other studies (<a href="https://www.ncbi.nlm.nih.gov/pubmed/17766449/">2</a>, <a href="http://www.ncbi.nlm.nih.gov/pubmed/21067672">3</a>, <a href="http://www.ncbi.nlm.nih.gov/pubmed/21212956">4</a>, <a href="http://www.ncbi.nlm.nih.gov/pubmed/16563685">5</a>). The common food source of most of these studies is cheese/dairy, which shows the higher number of CFU and AR gene heterogeneity because of the presence of lactic acid bacteria. This is also relevant for fermented foods. </span></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;"><br />
</span></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;">The picture gets worse if we consider that the presence of AR bacteria and multiple resistance genes have been found in microbiota of breast-fed babies without previous exposure to antibiotics, as well as in some breast-milk samples (<a href="http://www.ncbi.nlm.nih.gov/pubmed/16965348">6</a>, <a href="http://www.ncbi.nlm.nih.gov/pubmed/21821748">7</a>). </span></div><br />
<div style="text-align: justify;"><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;">In my opinion, antibiotic resistance is the main public health problem nowadays. While it may be smart to avoid certain foods which have potential carriers, the problem dont lies in the presence of AR genes <i>per se</i>, but in the horizontal transfer between AR bacteria and human commensal bacteria, which can then transfer resistance genes to pathogenic bacteria that are present in the human microbiota. These AR genes can also be transferred to pathogenic bacteria that can colonize the human digestive tract. As persistence of AR genes in the absence of antibiotic selective pressure has been observed, it seems that some AR bacteria might have a fitness advantage over wild-type strains. Thus, in evolutionary terms, reducing the exposure to antibiotics would not solve the problem (at least not in the short term) because the AR phenotype and the compensatory mutations associated are part of the evolution (compensatory evolution) of bacteria. </span></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;"><br />
</span></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;">Having this in mind, the most prudent preventive measure is maintaining a healthy immune system and gut microbiota via nutrition. Competition among bacterial populations is an important aspect of pathogen colonization. In this way, dysbiosis contributes to the establishment of pathogenic colonies in the gut. Avoiding any exposure to environmental pathogens is a double edge sword: you are avoiding the <i>bad</i> ones but also the <i>good</i> ones. </span></div><br />
<span style="float: left; padding: 5px;"><a href="http://www.researchblogging.org"><img alt="ResearchBlogging.org" src="http://www.researchblogging.org/public/citation_icons/rb2_large_white.png" style="border:0;"/></a></span><span class="Z3988" title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.jtitle=FEMS+microbiology+letters&rft_id=info%3Apmid%2F16445749&rfr_id=info%3Asid%2Fresearchblogging.org&rft.atitle=Food+commensal+microbes+as+a+potentially+important+avenue+in+transmitting+antibiotic+resistance+genes.&rft.issn=0378-1097&rft.date=2006&rft.volume=254&rft.issue=2&rft.spage=226&rft.epage=31&rft.artnum=&rft.au=Wang+HH&rft.au=Manuzon+M&rft.au=Lehman+M&rft.au=Wan+K&rft.au=Luo+H&rft.au=Wittum+TE&rft.au=Yousef+A&rft.au=Bakaletz+LO&rfe_dat=bpr3.included=1;bpr3.tags=Biology%2CHealth%2CBiology%2C+Nutrition%2C+Biochemistry%2C+Genetics+%2C+Public+Health">Wang HH, Manuzon M, Lehman M, Wan K, Luo H, Wittum TE, Yousef A, & Bakaletz LO (2006). Food commensal microbes as a potentially important avenue in transmitting antibiotic resistance genes. <span style="font-style: italic;">FEMS microbiology letters, 254</span> (2), 226-31 PMID: <a rev="review" href="http://www.ncbi.nlm.nih.gov/pubmed/16445749">16445749</a></span>Unknownnoreply@blogger.com2tag:blogger.com,1999:blog-4724838399830873886.post-31126484221228144152011-10-04T05:47:00.000-07:002017-03-13T06:08:02.537-07:00Ketogenic diet and STZ-induced diabetes<div style="text-align: justify;"><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;"><a href="http://www.sciencedaily.com/releases/2011/08/110814141432.htm">High fat diets cause diabetes</a>. At least this is what we are told. Researchers frequently use <a href="http://en.wikipedia.org/wiki/Streptozotocin">streptozotocin</a> (STZ) to induce diabetes in experimental animals. So, following the logic, a low carbohydrate ketogenic diet (LCKD) plus STZ would make rats extremely diabetic, with a very reduced chance to survive in the long term. </span></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;"><br />
</span></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;">So let's see what happens when STZ-treated rats are fed a normal chow diet (ND), a LCKD and a high carbohydrate diet (HCHO) (<a href="http://www.ncbi.nlm.nih.gov/pubmed/21943927">1</a>). The macronutrient ratios for the latter were (C/F/P): LCKD 10/60/30 and HCHO 70/10/20.</span><br />
<br />
<span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;">Bodyweight remained constant in the LCKD group, while it was reduced significantly in the HCHO and ND groups. In the latter, after the administration of STZ, blood glucose (BG) increased from 105mg/dL at baseline to 650mg/dL at the end of the experimental period. In contrast, the LCKD group maintained BG levels around 100mg/dL. Food intake also was drastically increased in HCHO and ND groups, showing <a href="http://en.wikipedia.org/wiki/Polyphagia">polyphagia</a>. The LCKD rats showed a little increased in food intake, then decreased and remained constant during the whole study. Water intake was also constant in the LCKD compared to HCHO and ND. Urine output was also increased in the latter groups. (Remember the "three P's" of diabetes: polydipsia, polyphagia and polyurea). Glucosuria after STZ injection reached 1000mg/dL. However, LCKD showed negative glucosuria. Summing up: LCKD rats didnt show any marker of diabetes comared to HCHO and ND rats. They maintained calorie intake, weight and BG levels normal. No polydipsia, polyphagia or polyurea. </span></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;"><br />
</span></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;">One recent study warned about the mechanism by which high fat diets could cause diabetes and beta-cell dysfunction. Yes, this is the famous study by Ohtsubo et al (<a href="http://www.ncbi.nlm.nih.gov/pubmed/21841783">2</a>). For a more comprehensive review of this study please refer to the one written by <a href="http://www.marksdailyapple.com/does-a-high-fat-diet-cause-type-2-diabetes/">Denise Minger</a>. In a nutshell, what the authors found was that elevated concentration of free fatty acids (FFA) caused nuclear exclusion and reduced expression of FOXA2 and HNF1A transcription factors in beta cells. This resulted in depletion of GnT-4a glycosylation and glucose transporter expression, leading to beta-cell dysfunction. This is one mechanism by which lipotoxicity contributes to diabetes onset. However, STZ causes cell death in pancreatic beta-cells through methylation, the release of free radicals or by the formation of nitric oxide. The mechanism found by Ohtsubo might be reversible. Beta-cell destruction might not. This is one of the most important problems with advanced diabetes, and might be involved in the evolution of type 2 into type 1 diabetes (<a href="http://www.ncbi.nlm.nih.gov/pubmed/11742411">3</a>). Thus, studies using models of beta-cell destruction might be more relevant for understanding the basis of autoimmune or chronic uncontrolled diabetes.</span></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;"><br />
</span></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;">This leads us to the most interesting part of the resent study. The authors assessed the histology of the Langerhans islets in the different rats by <a href="http://en.wikipedia.org/wiki/H%26E_stain">H&E staining</a>. </span></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;"><br />
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<tr><td style="text-align: center;"><a href="http://4.bp.blogspot.com/-iQccZBX73Cg/Tojuc2R7d0I/AAAAAAAAAGw/Jnak9VTV9iA/s1600/HEstaining1.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="233" src="http://4.bp.blogspot.com/-iQccZBX73Cg/Tojuc2R7d0I/AAAAAAAAAGw/Jnak9VTV9iA/s400/HEstaining1.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span class="Apple-style-span" style="background-color: white; font-family: arial, verdana, helvetica, sans-serif; font-size: 12px;">Copyright © 2010 Elsevier GmbH. All rights reserved.</span></td></tr>
</tbody></table><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;"><br />
</span></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;">(a) and (b) show the sections of the pancreas from control HCHO and ND rats. Circles show islets of Langerhans and arrows show vacuoles. (d) and (e) are from diabetic HCHO and ND rats, respectively. As can be seen, there is almost no islet left after STZ administration. </span><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;">On the other hand, diabetic LCKD rats showed no reduction of islets compared to LCKD controls ((c) and (f)). </span></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;"><br />
</span></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;">To further assess the efect of the different diets on beta-cell destruction, the authors used Gomori's Chrome Alum Haematoxylin-Phloxine stain. </span></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;"><br />
</span></div><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://1.bp.blogspot.com/-PwQyviQAWLM/TojveGDDRZI/AAAAAAAAAG0/k8CP6wl80QY/s1600/HEstaining2.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="221" src="http://1.bp.blogspot.com/-PwQyviQAWLM/TojveGDDRZI/AAAAAAAAAG0/k8CP6wl80QY/s400/HEstaining2.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span class="Apple-style-span" style="background-color: white; font-family: arial, verdana, helvetica, sans-serif; font-size: 12px;">Copyright © 2010 Elsevier GmbH. All rights reserved.</span></td></tr>
</tbody></table><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;"><br />
</span></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;">Beta-cells are stained blue, alfa-cells are stained red and delta-cells are stained pink. (a), (b) and (c) are control ND, HCHO and LCKD; (d), (e) and (f) are diabetic ND, HCHO and LCKD, respectively. </span></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;"><br />
</span></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;">Overall, there was a clear protection against beta-cell destruction in the diabetic LCKD rats, compared to diabetic HCHO and ND rats. However, the number of beta-cells in control rats was not different between groups. </span></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;"><br />
</span></div><div class="separator" style="clear: both; text-align: center;"></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;">How can a ketogenic diet can prevent the onset of diabetes induced by STZ and a high-fat diet cause diabetes? Isnt a ketogenic diet a high-fat diet? First, a high-fat diet is not necessarily a ketogenic diet. The term "high-fat diet" is used without a consensus in the literature, so a high sugar-high fat diet might be promoted as a high-fat diet (this is why is EXTREMELY important to read the methods). Second, lipotoxicity is a major cause of metabolic dysfunction. However, lipotoxicity doesnt implies a high-fat diet. It implies dysregulation of lipid metabolism. If anything, a ketogenic diet should restore a normal lipid metabolism. Third, there is a difference in comparing <i>in vitro </i>results with <i>in vivo </i>results. I have highlighted the importance of this distinction <a href="http://www.lucastafur.com/2011/02/integrative-metabolism-physiology-case_03.html">before</a>. Finally, diabetes is a highly complex disease. I believe that the most serious cases have definitely an immune component, so there is targeted destruction of beta-cells. The authors speculated that the ketogenic diet prevented diabetes by the antioxidant effect of ketone bodies (because one of the cytotoxic effects of STZ in beta-cells is mediated by the increase in free radicals). </span></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;"><br />
</span></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;">In conclusion, saying that high-fat ketogenic diets cause diabetes is as silly as saying that high carbohydrate diets cause diabetes. There is an extreme metabolic flexibility present in <b>healthy</b> humans, which can adapt to a wide range of macronutrient ratios. Food toxins, as stressed by other authors are another source of problems, which can confound the effect of different diets. </span><br />
<span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;"><br />
</span><br />
<span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;">People with diabetes might benefit from low carbohydrate diets not only by the proximate effect of the diet (less dietary glucose, which treats the symptom, not the cause), but because of calorie restriction, which alleviates lipotoxicity. This can also be achieved with an hypocaloric high-carbohydrate diet. But with people in with autoimmune type I diabetes, <a href="http://en.wikipedia.org/wiki/Latent_autoimmune_diabetes">LADA</a>, or severe cases of type 2 diabetes, a ketogenic diet could prevent progression of the disease more efficiently, preventing oxidative stress-mediated cell death. </span></div><div style="text-align: justify;"><br />
</div><span style="float: left; padding-bottom: 5px; padding-left: 5px; padding-right: 5px; padding-top: 5px;"><a href="http://www.researchblogging.org/"><img alt="ResearchBlogging.org" src="http://www.researchblogging.org/public/citation_icons/rb2_large_gray.png" style="border: 0pt none;" /></a></span><span class="Z3988" title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.jtitle=Experimental+and+toxicologic+pathology+%3A+official+journal+of+the+Gesellschaft+fur+Toxikologische+Pathologie&rft_id=info%3Apmid%2F21943927&rfr_id=info%3Asid%2Fresearchblogging.org&rft.atitle=Low+carbohydrate+ketogenic+diet+prevents+the+induction+of+diabetes+using+streptozotocin+in+rats.&rft.issn=0940-2993&rft.date=2011&rft.volume=63&rft.issue=7-8&rft.spage=663&rft.epage=9&rft.artnum=&rft.au=Al-Khalifa+A&rft.au=Mathew+TC&rft.au=Al-Zaid+NS&rft.au=Mathew+E&rft.au=Dashti+H&rfe_dat=bpr3.included=1;bpr3.tags=Biology%2CNutrition%2C+Immunology%2C+Molecular+Biology">Al-Khalifa A, Mathew TC, Al-Zaid NS, Mathew E, & Dashti H (2011). Low carbohydrate ketogenic diet prevents the induction of diabetes using streptozotocin in rats. <span style="font-style: italic;">Experimental and toxicologic pathology : official journal of the Gesellschaft fur Toxikologische Pathologie, 63</span> (7-8), 663-9 PMID: <a href="http://www.ncbi.nlm.nih.gov/pubmed/21943927" rev="review">21943927</a></span>Unknownnoreply@blogger.com23tag:blogger.com,1999:blog-4724838399830873886.post-46200226654113207472011-10-02T12:12:00.000-07:002017-03-13T06:08:02.542-07:00Good worms<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: left; margin-right: 1em; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="http://upload.wikimedia.org/wikipedia/commons/2/28/Schistosome_Parasite_SEM.jpg" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="320" src="http://upload.wikimedia.org/wikipedia/commons/2/28/Schistosome_Parasite_SEM.jpg" width="257" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">(bioquicknews.com)</td></tr>
</tbody></table><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;"><i>Schistosoma mansoni</i> (left) is a very interesting worm. In fact, it is one of the "<a href="http://www.lucastafur.com/2011/09/old-friends-hypothesis.html">Old Friends</a>" with which we have co-evolved. This parasite is the responsible for the development of <a href="http://en.wikipedia.org/wiki/Schistosomiasis">schistosomiasis</a>, to which no vaccine has been developed yet. </span></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;"><br />
</span></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;">What seems most interesting about <i>S.mansoni</i> is its capacity to modulate the human immune system<i>. </i>While in the host, each adult worm pair releases 200-300 eggs each day, which maturate during 5-6 days. Maturation involves forming the Von Lichtenberg's envelope on the inside of the egg shell from which proteins are secreted. The host reacts to the eggs and the proteins secreted, mounting a Th2-type immune response. One group of proteins present in the egg are soluble egg antigens (SEA). The exact mechanism by which SEA and other proteins secreted affect the immune response is not entirely clear. Nevertheless, it seems to involve C-type lectin receptors (CLR), as most antigenic proteins identified so far are glycoproteins with some conserved glycans (<a href="http://www.ncbi.nlm.nih.gov/pubmed/21616068">1</a>). </span></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;"><br />
</span></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;">One characteristic of parasitic helminths like <i>S. mansoni</i> is that they have developed many strategies to supress the host response, thereby controlling the inflammatory response. This has been a mechanism acquired through co-evolution with its mammalian hosts, like humans. As parasite driven infection induces a Th2-type immune response, it can be hypothesized that some parasites can modulate the onset and progression of Th1-type autoimmune diseases, like type I diabetes. </span></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;"><br />
</span></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;"><a href="http://en.wikipedia.org/wiki/NOD_mice">NOD mice</a> is a model for autoimmune type I diabetes. When infected with <i>S.mansoni</i> or exposed to SEA, these mice do not develop diabetes (<a href="http://www.ncbi.nlm.nih.gov/pubmed/12731071">2</a>). To try to elucidate the mechanism, Zaccone et al (<a href="http://www.ncbi.nlm.nih.gov/pubmed/19291704">3</a>) examined the effect of SEA on Foxp3+ Treg levels. Now, Treg cells are very important for controlling the immune response (hence the name Treg-regulatory T cells). One of the most important roles of these cells is establishing self-tolerance. Any failure of self tolerance would potentially lead to the development of autoimmunity. What has been observed is that injection of SEA to NOD mice increases the population of CD4+Foxp3+T cells in the pancreas. SEA generates Foxp3+ T cells from naïve CD4 T cells in a TGF-b dependent fashion. This effect was shown to happen directly and indirectly (by upregulation of CLR on dendritic cells), which suggests a synergistic response. Specific CLR upregulated by SEA include galectins 1 and 3, SIGN-R1 and DEC-205. </span><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;">Moreover, SEA is capable to alternatively activate macrophages (<a href="http://www.ncbi.nlm.nih.gov/pubmed/20204176">4</a>), consistent with the effect of other helminths (<a href="http://www.ncbi.nlm.nih.gov/pubmed/17702561">5</a>). Depletion of CD25+ T cells from splenocytes of SEA-treated NOD mice restored their ability to transfer diabetes to recipient animals, supporting the role of Treg in diabetes prevention in SEA-treated NOD mice. In contrast, depletion of CD25+ T cells from splenocytes of serum worm antigen (SWA)-treated NOD mice did not restore the ability to transfer diabetes to recipient NOD mice. This suggests that SEA and SWA protect against diabetes by different mechanisms, and that protection from SEA is mediated primarily by Tregs.</span></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;"><br />
</span></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;">The protective effect of <i>S.mansoni</i> on other Th-1 type autoimmune diseases has also been observed. For instance, helminth infection seems to protect against the course of multiple sclerosis (MS) (<a href="http://www.ncbi.nlm.nih.gov/pubmed/17230481">6</a>). Although this study did not correlate infection with <i>S.mansoni</i> and the severity of MS exclusively, animal models of experimental autoimmune encephalitis (EAE) (an animal model for MS) infected with <i>S.mansoni</i> exhibit reduced levels of proinflammatory cytokines and CNS inflammation (<a href="http://www.ncbi.nlm.nih.gov/pubmed/12933842">7</a>, <a href="http://www.ncbi.nlm.nih.gov/pubmed/12502726">8</a>). Exposure to <i>S.mansoni</i> eggs and/or infection also protects mice from TBNS-induced colitis (animal model for Chron's disease) </span><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;">(<a href="http://www.ncbi.nlm.nih.gov/pubmed/12431903">9</a>, <a href="http://www.ncbi.nlm.nih.gov/pubmed/14684583">10</a>)</span><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;">, collagen-induced arthritis (animal model for rheumatoid arthritis) (<a href="http://www.ncbi.nlm.nih.gov/pubmed/18835272">11</a>), Grave's disease (<a href="http://www.ncbi.nlm.nih.gov/pubmed/15265954/">12</a>), and allergic diseases (<a href="http://www.ncbi.nlm.nih.gov/pubmed/17689595">13</a>, <a href="http://www.ncbi.nlm.nih.gov/pubmed/18824533/">14</a>). This challenges the Th1/Th2 dichotomy and suggests that there are other mechanisms by which <i>S.mansoni</i> modulates the immune system. </span></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;"><br />
</span></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;">The rise in inflammatory and autoimmune conditions may not only have a nutritional basis. Lack of exposure to some essential parasites for the development of the immune system by adoption of extreme hygiene practices during early infancy may increase the risk of allergic and autoimmune diseases. A healthy lifestyle should not only include avoiding industrialized foods, but also being exposed to different pathogens which help shape our immune system. </span></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;"><br />
</span></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;"><br />
</span></div><span style="float: left; padding-bottom: 5px; padding-left: 5px; padding-right: 5px; padding-top: 5px;"><a href="http://www.researchblogging.org/"><img alt="ResearchBlogging.org" src="http://www.researchblogging.org/public/citation_icons/rb2_large_white.png" style="border: 0;" /></a></span><span class="Z3988" title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.jtitle=European+journal+of+immunology&rft_id=info%3Apmid%2F19291704&rfr_id=info%3Asid%2Fresearchblogging.org&rft.atitle=Schistosoma+mansoni+egg+antigens+induce+Treg+that+participate+in+diabetes+prevention+in+NOD+mice.&rft.issn=0014-2980&rft.date=2009&rft.volume=39&rft.issue=4&rft.spage=1098&rft.epage=107&rft.artnum=&rft.au=Zaccone+P&rft.au=Burton+O&rft.au=Miller+N&rft.au=Jones+FM&rft.au=Dunne+DW&rft.au=Cooke+A&rfe_dat=bpr3.included=1;bpr3.tags=Health%2CBiology%2C+Nutrition">Zaccone P, Burton O, Miller N, Jones FM, Dunne DW, & Cooke A (2009). Schistosoma mansoni egg antigens induce Treg that participate in diabetes prevention in NOD mice. <span style="font-style: italic;">European journal of immunology, 39</span> (4), 1098-107 PMID: <a href="http://www.ncbi.nlm.nih.gov/pubmed/19291704" rev="review">19291704</a></span>Unknownnoreply@blogger.com1tag:blogger.com,1999:blog-4724838399830873886.post-43531598996639410812011-09-16T13:05:00.000-07:002017-03-13T06:08:59.843-07:00The "Old Friends" Hypothesis<span style="font-family: Georgia, 'Times New Roman', serif;">Modern humans (as all mammals) have co-evolved with different bacteria, viruses and parasites. Until the development of vaccines and hygiene, these organisms lived in the human body in relatively constant amounts, varying between geographical regions and specific events. Infectious diseases were, together with violent deaths and accidents, the main cause of death for primitive humans. Before the development of modern medical practices, most infectious diseases were lethal. Even while this reduced greatly the impact of different pathogens on death rates, infectious diseases are still in the top 10 causes of death in the world (<a href="http://www.who.int/mediacentre/factsheets/fs310/en/index.html">1</a>). </span><br />
<br />
<span style="font-family: Georgia, 'Times New Roman', serif;"><u><b>Mutualism and evolved dependence</b></u></span><br />
<br />
<span style="font-family: Georgia, 'Times New Roman', serif;">Mutualism refers to a type of biological interaction between two organisms in which each individual derives a fitness benefit. Putting it simply, both organisms benefit from the presence of the other. On the other hand, evolved dependence refers to the situation in which two organisms have evolved together, so they have adapted and become dependent on each other for survival and proper functioning. We can quantify this parameter as "the performance difference between the genotype that is adapted to the partner's absence and the genotype that is adapted to its presence, both measured in the absence of the partner"(<a href="http://onlinelibrary.wiley.com/doi/10.1111/j.0022-0477.2004.00952.x/full">2</a>). This is illustrated in the following figure (here mutualism is referred as "proximate mutualism/response"):</span><br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://4.bp.blogspot.com/-MeVTfAvQHj4/TnKC71uwtOI/AAAAAAAAAGc/UNADyo1wdlE/s1600/JEC_952_f1.gif" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="195" src="http://4.bp.blogspot.com/-MeVTfAvQHj4/TnKC71uwtOI/AAAAAAAAAGc/UNADyo1wdlE/s400/JEC_952_f1.gif" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span class="Apple-style-span" style="background-color: #e1e9eb; color: #105461; font-family: Arial, 'Lucida Grande', Geneva, Verdana, Helvetica, sans-serif; font-size: 11px; line-height: 14px;">Copyright © 1999–2011 John Wiley & Sons, Inc.</span></td></tr>
</tbody></table><br />
<span style="font-family: Georgia, 'Times New Roman', serif;">If we have this data, we can calculate:</span><br />
<br />
<span style="font-family: Georgia, 'Times New Roman', serif;">a. The proximate response of the organism to partner removal for individual genotypes: FGp/p - FGp/a (genotype adapted to the partner) and FGa/p</span> - <span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;">FGa/a</span> <span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;">(genotype adapted to the absence of the partner).</span><br />
<br />
<span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;">b. The ultimate response of the organism to removal of the partner: FGp/p - FGa/a. This reflects performance between genotypes. </span><br />
<br />
<span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;">c. Evolved dependence: FGa/a - FGp/a (performance difference in the absence of the partner). </span><br />
<br />
<span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;"><b><u>The Old Friends</u></b></span><br />
<br />
<span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;">Paleolithic populations carried several types of organisms as for example, "heirloom species" inherited from their primate ancestors. They would have also been exposed to zoonoses that they picked up during carrion scavenging. In addition, they would have consumed several miligrams of harmless environmental saprophytes daily. Rook has termed these organisms as "pseudocommensals" (or "the Old Friends") (<a href="http://www.ncbi.nlm.nih.gov/pubmed/21734378">3</a>). The shift to agriculture and husbandry will have had little effect on exposure to "pseudocommensals" or to the heirloom species, but the more sedentary lifestyle increased orofecal transmission and caused prolonged contact with animals. The latter led to adaptation to several animal viruses. However, evolved dependence between humans and neolithic viruses is unlikely, as Rook remarks:</span><br />
<blockquote><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;">"(...) the viruses acquired during the Neolithic era, such as influenza (B and C), smallpox, mumps and measles, cannot have become endemic until populations were large enough. This required communities of several hundreds of thousands, which did not occur until the appearance of cities 2,000–3,000 years ago. Since this represents only 100–150 generations, extremely strong selection pressure would have been required for evolved dependence to appear, and this seems unlikely. Moreover, most humans did not live in such large groups, and these viruses were, for example, absent from pre-Columbian American populations.</span><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;">"</span></blockquote><span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;">The neolithic transition did not result in loss of exposure to the Old Friends as until the modern era, more than 97% of the population still lived in rural environments, close to mud, animals and feces, which are the sources of these organisms. Since the mid-19th century, as public health measures and antibiotics appeared, the exposure to many of the old friends has been drastically diminished or delayed. </span><br />
<br />
<span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;"><b><u>Evolved dependence between humans and the Old Friends</u></b></span><br />
<br />
<span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;">The main evolutionary principle relevant for the Old Friends Hypothesis is that the presence of the Old Friends would have led to adaptations by the host. Rather than provoking damaging aggresive immune responses, an anti-inflammatory equilibrium is established. If an aggresive and exaggerated immune response is developed, the survival of both the host and parasite would be compromised. </span><br />
<br />
<span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;">Applying the concepts mentioned above, evolved dependence implies that a genotype has adapted to the partner. This is the case for human-parasite co-evolution. Accordingly, Fumagalli et al (<a href="http://www.ncbi.nlm.nih.gov/pubmed/19468064">4</a>) found a high frequency of SNPs in interleukin/interleukin receptor genes in geographical areas with the highest number of endemic helminth species. Additionally, they report that six of nine risk alleles for IBD and celiac disease were significantly correlated with micropathogen richness*. Of all interleukin genes analyzed, most members of the IL-1 signaling pathway correlated with pathogen richness. IL-1A and IL-1B are pleiotropic cytokines that play a central role in immunity and inflammation. Macropathogen richness also correlated strongly with <i>IL4</i>, <i>IL4R</i> and <i>IL10 </i>(Th2 response) and <i>IL19, IL20</i> (known to induce skin inflammatory responses) SNPs. Finally, SNPs in <i>IL2B, IL15 </i>and <i>IL15RA</i> were correlated with macropathogen richness. IL-2B and IL-RA are part of a trimeric complex which binds IL-15, which has been related to immune protection of gut tissues by stimulating tight junction formation. </span><br />
<br />
<span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;">This findings show that pathogens, and more specifically helminths are a major selective force for interleukin genes. The Old Friends modulate dendritic cells (DC) towards Treg, attenuating the immune response. The genetic variants and SNPs shown responsive to helminths suggest that the adaptation to the constitutive presence of these pathogens is reflected by an increase in pro-inflammatory cytokines, so the inflammation equilibrium is achieved. The lack of this background anti-inflammatory stimuli due to absence of pathogens by the modern lifestyle shifts the balance towards excessive inflammation. </span><br />
<br />
<span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;"><b><u>Mutualism and gut flora</u></b></span><br />
<br />
<span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;">Human gut microbiota is the perfect example of mutualism. The composition of gut flora is dynamic, responsive to environmental factors and geographical location. Bacteria are also transmitted between humans and other animals, shaping the composition of microbial communities in populations and families. </span><br />
<br />
<span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;">Many attributes that were assumed to be human traits might in fact be the result of human-microbe interactions. Ongoing research is demonstrating the importance of the composition of gut microbial communities for human health. There is more that we dont know than what we know about specific bacteria in the human gut. This is why for example, prebiotics and probiotics (applies to also the so-called "probiotic diets") assumed to be healthy by increasing the population of certain species might not be healthy in the long term, because the effect on other species is not known. This also affects the human gut virome, which is a very recent area of research. Finally, interactions between different pathogens (ie. helminths) with gut microbiota/viruses represent another potential factor for immune regulation. </span><br />
<br />
<span class="Apple-style-span" style="font-family: Georgia, 'Times New Roman', serif;">* Pathogen richness refers to the number of different pathogen species/genera in a specific geographic location. In the study, micropathogens included bacteria, viruses, fungi and protozoa. Macropathogens included insects, arthropods and helminths, but because parasitic worms were the most abundant class (90% of species/genera), the term basically meant helminths. </span>Unknownnoreply@blogger.com8tag:blogger.com,1999:blog-4724838399830873886.post-70669831421037283692011-09-03T14:18:00.001-07:002017-03-13T06:08:59.859-07:00Fruit and ketoacidosis<span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;">One more reason to go easy on fruit. You might end like <a href="http://www.ncbi.nlm.nih.gov/pubmed/21519781">this guy</a>. </span><br /><br /><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;">From the paper:</span><br /><blockquote><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;">"During the last decade, our patient had being suffering from a <b>progressive eating disorder</b>, starting with a lacto-ovovegetarian diet followed by a<b> strict vegetarian diet, complying with all the alimentary habits that involve fruitarianism</b>. <b>After a week of complete fasting, patient was brought to our hospital by his family, alerted by his noticeable behavioural alteration</b>. Previous week strict fasting was the cause that triggered severe ketoacidosis."</span></blockquote><blockquote><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;">"In our clinical experience, <b>followers of this way of life [fruitarianism] are vulnerable not only to suffer nutritional deficiencies</b>, but also to develop <b>serious metabolic impairments that may be life-threatening</b>, as occurred in our patient."</span></blockquote><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;">This is the first case of ketoacidosis associated with fruitarianism (at glance, sounds like an oxymoron). The trigger was one week of fasting, which produces a metabolic milieu completely different from that of somebody eating a high sugar diet. </span><br /><blockquote><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;">"A 35 year old male patient with a medical history of <b>three previous admissions to psychiatric units</b> was brought to the Emergency Room via ambulance, presenting with behavioural disturbances, including <b>aggressiveness</b> and voluntary complete fasting for over a week. In the last 10 years, the patient followed a strict vegetarian diet that leads him progressively to restrict his diet only to fruit. On presentation, <b>patient was ill appearing with psychomotor impairment and incoherent speech</b>. On physical examination, he was hemodynamically stable and he had a <b>body mass index (BMI) of 16</b>."</span></blockquote><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;">The biochemical markers can be seen in the full text (its free). When admitted, the patient had several markers abnormal, seen in cases of malnutrition. He showed some responses to refeeding similar to that of the "<a href="http://en.wikipedia.org/wiki/Refeeding_syndrome">Refeeding Syndrome</a>" (see Table I). </span><br /><blockquote><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;">"<b>Patient motivation for eating only fruits was based on the desire to avoid harming animals and vegetables</b>. He only allowed himself to eat fruit because it was produced by a plant, and consumption of the fruit did not kill the plant. <b>The patient refused to receive tube feeding claiming that "receiving enteral nutrition won´t allow him to follow his dietary habit"</b>, a subclavian central venous line was placed and total parenteral nutrition was initiated with supplemental phosphate, potassium, calcium and magnesium. A psychiatric consult was requested, and a diagnosis of undetermined psychotic disorder was given. Patient remained hemodynamically stable with normal urine output."</span></blockquote><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;">Sounds like a "hardcore" dogma follower (although this is not exclusive for vegetarianism).</span><br /><blockquote><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;">"Even though, the patient underwent strict fasting for only a week, <b>he showed a protein-calorie malnourished state</b>, as revealed biochemical markers of nutritional status that were obtained plasma albumine level, 2.3 g/dl; retinol-binding protein (RBP) 2.85 mg/dl; transferrin 108 mg/dl and prealbumin, 12.6 mg/dl. Also levels of vitamins were obtained B<sub>12</sub> 464.00 pg/ml (200.00-732.00); folate 2.10 ng/ml (2.80-13.50) and Vitamin D of 17 (30ng/ml). These findings and patient´s underweight alert us of starvation as the possible cause of his ketoacidotic state. Intravenous fluid replacement and parenteral nutrition were discontinued and enteral feedings were started on hospital day 3. Also, the acidosis was resolved, and following cessation of insulin infusion, patient remained normoglycemic."</span></blockquote><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;">Normally, it takes weeks or even months for malnutrition and micronutrient deficiencies to start to appear. The fact that it only took him 1 week to develop ketoacidosis reflects that this patient had severe macro and micronutrient deficiencies developed over the time. This is important because some people think their diet is OK because they feel normal, while there is a severe underlying subclinical nutrition deficiency. </span><br /><br /><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;">Bottomline: say no to dietary non-sense and eat your meat. </span><br /><br /><span style="float: left; padding: 5px;"><a href="http://www.researchblogging.org"><img alt="ResearchBlogging.org" src="http://www.researchblogging.org/public/citation_icons/rb2_large_white.png" style="border:0;"/></a></span><span class="Z3988" title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.jtitle=Nutricion+hospitalaria+%3A+organo+oficial+de+la+Sociedad+Espanola+de+Nutricion+Parenteral+y+Enteral&rft_id=info%3Apmid%2F21519781&rfr_id=info%3Asid%2Fresearchblogging.org&rft.atitle=Severe+ketoacidosis+secondary+to+starvation+in+a+frutarian+patient.&rft.issn=0212-1611&rft.date=2010&rft.volume=25&rft.issue=6&rft.spage=1049&rft.epage=52&rft.artnum=&rft.au=Causso+C&rft.au=Arrieta+F&rft.au=Hern%C3%A1ndez+J&rft.au=Botella-Carretero+JI&rft.au=Muro+M&rft.au=Puerta+C&rft.au=Balsa+JA&rft.au=Zamarron+I&rft.au=V%C3%A1zquez+C&rfe_dat=bpr3.included=1;bpr3.tags=Health%2CBiology%2C+Nutrition">Causso C, Arrieta F, Hernández J, Botella-Carretero JI, Muro M, Puerta C, Balsa JA, Zamarron I, & Vázquez C (2010). Severe ketoacidosis secondary to starvation in a frutarian patient. <span style="font-style: italic;">Nutricion hospitalaria : organo oficial de la Sociedad Espanola de Nutricion Parenteral y Enteral, 25</span> (6), 1049-52 PMID: <a rev="review" href="http://www.ncbi.nlm.nih.gov/pubmed/21519781">21519781</a></span>Unknownnoreply@blogger.com2tag:blogger.com,1999:blog-4724838399830873886.post-5086998129785034172011-08-31T20:04:00.001-07:002017-03-13T06:08:59.851-07:00Dietary fat, CCK and the cholinergic antiinflammatory pathway<span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"><u>Background</u></span><br /><br /><div style="text-align: right;"></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;">One of the most important antiinflammatory pathways is mediated by the vagus nerve. Vagal stimulation increases the release of acetylcholine, which then interacts with the alpha 7 subunit of the nicotinic receptor on macrophages, activating the Jak2-STAT3 signaling pathway (<a href="http://www.ncbi.nlm.nih.gov/pubmed/16025117/">1</a>). This interaction inhibits macrophage activation and thus reduces inflammation. This pathway is known as the cholinergic antiinflammatory pathway (CAP)*. Stimulation of CAP has been shown to reduce TNF-a, IL-1b, IL-6 and IL-18 levels during endotoxemia (<a href="http://www.ncbi.nlm.nih.gov/pubmed/10839541">2</a>) and NF-kB activation (<a href="http://www.ncbi.nlm.nih.gov/pubmed/19675277">3</a>). The autonomic nervous system controls inflammation by the adrenergic pro-inflammatory pathway and the CAP (<a href="http://www.ncbi.nlm.nih.gov/pubmed/18802444">4</a>):<br /><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"> </span><span class="Apple-style-span" style="color: #7c7c7c;"><i><br /></i></span></span></div><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody><br /><tr><td style="text-align: center;"><a href="http://www.nature.com/nri/journal/v8/n10/images/nri2402-f4.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="340" src="http://www.nature.com/nri/journal/v8/n10/images/nri2402-f4.jpg" width="400" /></a></td></tr><br /><tr><td class="tr-caption" style="text-align: center;">Nature Reviews Immunology 8, 776-787</td></tr><br /></tbody></table><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"><br /></span>Although there are different ways to stimulate the CAP, most research has been done either using electrical stimulation (or acetylcholine receptor agonists) or vagotomy in laboratory animals. As nutrition is a determinant factor contributing or reducing inflammation, it seems plausible to speculate about the role of different nutrients modulating the CAP. </span></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"></span></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"><br /><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;">Luyer et al (<a href="http://www.ncbi.nlm.nih.gov/pubmed/16216887">5</a>) tested the ability of dietary fat to modulate inflammation, by stimulating the release of cholecystokinin (CCK). They induced hemorragic shock in Sprague-Dawley rats, in order to increase proinflammatory cytokines such as IL-6 and TNF-a. They fed them either a low fat or high fat enteral nutrition, or fasting. Additionally, high-fat fed rats were </span></span><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;">vagotomized (VGX) or <a href="http://en.wikipedia.org/wiki/Sham_surgery">sham</a> vagotomized (Sham). </span></span><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;">Nutritional composition of both diets was as follows, as percentage of total energy:</span></span></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"></span></span></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"></span></span></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"><br /></span><u>High fat:</u> 6.9% protein, 40.9% carbohydrate, 52.2% fat.</span></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"><u>Low fat:</u> 6.9% protein, 75.4% carbohydrate, 16.7% fat.</span></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"></span></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"><br /><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;">Proteins were derived from lean milk and carbohydrates from a mixture of sucrose and corn starch. The lipid source was vegetable oil, cointaining 8.1% SFA, 58.9% MUFA (57.4% oleic acid), 28.2% PUFA (23% linoleic acid). The amount of n-3 and n-6 in the high fat nutrition was less than 5% of the total fat content. They found that:</span></span></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"></span></span></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"><br /></span>- High-fat enteral nutrition reduced hemorragic shock-induced TNF-a and IL-6 in Sham rats, compared to low-fat and fasted controls. Vagotomy nearly abolished the fat-induced reduction in these proinflammatory cytokines (TNF-a: 205 +/-11 pg/ml [VGX] vs. 5 +/-1 pg/ml [Sham]; IL-6: 80 +/-5 pg/ml [VGX] vs. 19 +/-9 pg/ml [Sham]).</span></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"> <br /><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;">Intestinal barrier function was assessed by a. bacterial translocation to distant organs, b. leakage of horseradish peroxidase (HRP) in isolated ileum-segments and c. plasma endotoxin levels. Increased intestinal permeability and impairment of gut barrier function is observed after induction of hemorragic shock. According to the reduction in proinflammatory cytokines, the high-fat nutrition reduced endotoxemia, permeability of ileum segments for HRP and bacterial translocation to distant organs, compared to fasted and low-fat Sham rats. Vagotomy reversed the protection of the high-fat diet, elevating plasma endotoxin levels (from 12 +/- 2 pg/ml to 28 +/-1 pg/ml), increasing leakage of HRP (from 1.1 +/- 0.7ug/ml to </span></span><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;">2.3 +/- 0.5ug/ml) and bacterial translocation (from 16 CFU/g tissue to 328 CFU/g). </span></span></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"><br /></span></span></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"></span></span></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"></span></span></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;">Using CCK-A and CCK-B receptor antagonists (or vehicle) in high-fat fed Sham rats, they showed that the protection from a high fat nutrition was mediated by CCK, as inhibition of CCK-A and CCK-B enhanced plasma TNF-a and IL-6 after hemorragic shock induction, as well as endotoxemia, HRP permeability and bacterial translocation to distant organs, compared to vehicle animals. Moreover, administration of <a href="http://en.wikipedia.org/wiki/Chlorisondamine">chlorisondamine</a> abrogated the inhibitory effects of a high-fat nutrition on the parameters previously evaluated, suggesting that inhibition of inflammation was mediated by stimulation of nicotinic receptors by way of efferent vagal fibers. The authors proposed the following model for explaining their observations:</span></span></div><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"><br /></span></span><br /><div class="separator" style="clear: both; text-align: center;"><a href="http://1.bp.blogspot.com/-H-GwsD1Ca0U/TlvUP4GXXNI/AAAAAAAAAGM/8eeW960sprM/s1600/CCK.PNG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="298" src="http://1.bp.blogspot.com/-H-GwsD1Ca0U/TlvUP4GXXNI/AAAAAAAAAGM/8eeW960sprM/s320/CCK.PNG" width="320" /></a></div><div class="separator" style="clear: both; text-align: center;"></div><br /><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;">The author's description is as follows:</span><br /><div style="text-align: justify;"><blockquote><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;">"Ingestion of high amounts of fat induces release of cholecystokinin (CCK) that binds to CCK-A and CCK-B receptors (CCK-r) located centrally or on peripheral vagal afferents. Activation of CCK-receptors triggers vagal efferents leading to an increase of acetylcholine (Ach), the principal parasympathetic neurotransmitter. Release of inflammatory cytokines such as TNF-a and IL-6 after activation of Toll-like receptors by bacterial products is inhibited by way of binding of acetylcholine to a-7 nicotinic (a7-nAch) receptors."</span></span></blockquote><span style="font-family: 'Trebuchet MS', sans-serif;">The findings of this study are remarkable, but as far as I can see, there was not much practical application after it was published. It isnt surprising. The same authors have published studies showing that a high-fat enteral nutrition protects the liver from the remote effects of hemorragic shock (high-fat treated animals had minimal liver injury, no evidence of mtDNA damage and significantly lower expression of stress proteins) (<a href="http://www.ncbi.nlm.nih.gov/pubmed/17566822">6</a>) and exposure to bacterial DNA (<a href="http://www.ncbi.nlm.nih.gov/pubmed/19070388">7</a>), and have proposed the utilization of a high-fat enteral nutrition after sever trauma to attenuate the inflammatory response (<a href="http://www.ncbi.nlm.nih.gov/pubmed/18948813">8</a>) and to treat inflammatory conditions (<a href="http://www.ncbi.nlm.nih.gov/pubmed/20585240">9</a>). </span><br /><br /><span style="font-family: 'Trebuchet MS', sans-serif;">Short after the publication of this paper, Tracey (<a href="http://www.ncbi.nlm.nih.gov/pubmed/16230472">10</a>) expanded the findings of Luyer et al., proposing fat-induced activation of the CAP for the treatment of inflammatory diseases:</span><br /><br /><div class="separator" style="clear: both; text-align: center;"><a href="http://jem.rupress.org/content/202/8/1017/F1.medium.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="400" src="http://jem.rupress.org/content/202/8/1017/F1.medium.jpg" width="318" /></a></div><br /><br /><span style="font-family: 'Trebuchet MS', sans-serif;">But controlled trials using this information is lacking. How can dietary fat, which is supposed to be inflammatory, can be anti-inflammatory? I guess that most nutrition researchers just ignore the awkward. Even recent papers dealing with the subject and the hypothesis of vagal nerve stimulation for treatment of inflammatory diseases do not mention anything about a high fat diet increasing the CAP. Moreover, you can find gems like this one, from a paper published in Medical Hypotheses recently by Undurti N. Das (<a href="http://www.ncbi.nlm.nih.gov/pubmed/21144670">11</a>), called "Vagus nerve stimulation as a strategy to prevent and manage metabolic syndrome":</span><br /><blockquote><span style="font-family: 'Trebuchet MS', sans-serif;">"It is proposed that consumption of energy dense food leads to acute raise in plasma glucose levels that triggers increased production of IL-6, TNF-a, and IL-18 by peripheral leukocytes, monocytes and macrophages [11]. Simultaneously, gut produces cholecystokinin that, in turn, enhances vagal tone and induces the release of acetylcholine [39]. Acetylcholine and the acute raise in plasma glucose levels trigger the release of insulin from pancreatic b cells that decrease plasma glucose levels and inhibit IL-6, TNF-a, and IL-18 secretion and thus, homeostasis is restored. However, <b>this regulatory system quickly fades in the face of continued ingestion of a fat-rich</b> and/or energy-dense diet. <b>Thus, fat-rich (especially saturated fat rich) and energy-dense foods promote insulin resistance, obesity, type 2 diabetes mellitus and the metabolic syndrome, in </b></span><span style="font-family: 'Trebuchet MS', sans-serif;"><b>part, by impairing nutrient-sensing systems that exist in the gut, liver and hypothalamus that are originally designed to limit food intake and enhance insulin sensitivity.</b>"</span></blockquote><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;">I find the statement "fat-rich (especially saturated fat rich) (...) foods promote..." misleading to say the least. In this regard, CCK could be a previously uncharacterized indirect antiinflammatory molecule. At the moment, this is highly speculative because the overall inflammation balance depends on several factors and not only stimulation of the CAP. </span><br /><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"><br /></span></div><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"> <span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;">* Or "inflammatory reflex".</span></span><br /><br /><span style="float: left; padding: 5px;"><a href="http://www.researchblogging.org"><img alt="ResearchBlogging.org" src="http://www.researchblogging.org/public/citation_icons/rb2_large_white.png" style="border:0;"/></a></span><span class="Z3988" title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.jtitle=The+Journal+of+experimental+medicine&rft_id=info%3Apmid%2F16216887&rfr_id=info%3Asid%2Fresearchblogging.org&rft.atitle=Nutritional+stimulation+of+cholecystokinin+receptors+inhibits+inflammation+via+the+vagus+nerve.&rft.issn=0022-1007&rft.date=2005&rft.volume=202&rft.issue=8&rft.spage=1023&rft.epage=9&rft.artnum=&rft.au=Luyer+MD&rft.au=Greve+JW&rft.au=Hadfoune+M&rft.au=Jacobs+JA&rft.au=Dejong+CH&rft.au=Buurman+WA&rfe_dat=bpr3.included=1;bpr3.tags=Health%2CBiology%2C+Nutrition">Luyer MD, Greve JW, Hadfoune M, Jacobs JA, Dejong CH, & Buurman WA (2005). Nutritional stimulation of cholecystokinin receptors inhibits inflammation via the vagus nerve. <span style="font-style: italic;">The Journal of experimental medicine, 202</span> (8), 1023-9 PMID: <a rev="review" href="http://www.ncbi.nlm.nih.gov/pubmed/16216887">16216887</a></span>Unknownnoreply@blogger.com5tag:blogger.com,1999:blog-4724838399830873886.post-32084478596777561852011-08-16T22:21:00.001-07:002017-03-13T06:08:59.840-07:00ChREBP: The forgotten factor<span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;">The discussion between Taubes and Guyenet has revived the long-life debate about the influence of carbohydrates/insulin in the pathogenesis of obesity and MetSyn. I think both hypotheses (carbohydrate excess and food reward) are complementary to each other. The problems associated with Taubes hypothesis are obvious and had been reviewed elsewhere. The food reward hypothesis, on the contrary, is very well documented in the literature and most researchers have shown consistent results. The question is, can food reward be a dominant factor in obesity in the absence of sugar? Generally, people get obese consuming high energy diets both high in sugar and fat. If we exclude sugar from the equation, would then the same people get obese? The food reward associated with junk food would be the same in the absence of sugar (assuming that there is sugar-free junk food)? Is high sugar (and probably veggie oils) the ultimate cause of leptin resistance and food reward? Is palatability only relevant when talking about high fat-high sugar foods? </span><br />
<br />
<span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;">I think this is why maybe the two hypotheses are complementary. I have yet to see any evidence of someone getting obese eating a low carbohydrate high fat diet. Sure, you can gain weight with a low carbohydrate diet, and you can regain the weight lost after a period of calorie restriction eating a low carbohydrate diet. But can you get obese in the absence of sugar? We will never see any formal evidence of this theory, but I think is a valid speculation.</span><br />
<br />
<span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;">Anyways, on to the topic of the post. As a nerd as I am, I like to look at physiological processes deep inside. When discussing about the role of sugar/carbohydrates in obesity, the transcription factor carbohydrate response element-binding protein (ChREBP) is hardly mentioned. This transcription factor binds to the carbohydrate response element (ChoRE) located in the promoter of target genes and stimulates transcription. ChREBP is a member of the basic helix-loop-helix/leucine zipper (bHLH/ZIP) family of transcription factors and its expression is ubiquitous, being most abundant in lipogenic organs such as liver, brown and white adipose tissues, small intestine, kidney and muscle. </span><br />
<br />
<span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;">Insulin and glucose both coordinate the transcription of key enzymes involved in de novo lipogenesis and glycolysis, the former by activation of SREBP1c and LXR. Both regulate different pathways which are integrated in the response to a high carbohydrate load (in this case, in the hepatocyte):</span><br />
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<tr><td class="tr-caption" style="text-align: center;"><span class="Apple-style-span" style="font-family: verdana, arial, sans-serif; font-size: 12px; line-height: 17px;">Copyright © 2011, The American Society for Clinical Investigation.</span></td></tr>
</tbody></table><span class="Apple-style-span" style="font-family: verdana, arial, sans-serif;"><span class="Apple-style-span" style="font-size: 12px; line-height: 17px;"><br />
</span></span><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;">At low blood glucose concentrations, ChREBP is located in the cytoplasm, phosphorylated at the Ser196 residue. When blood glucose levels rise, glucose enters the hepatocyte and is phosphorylated by glucokinase and then converted to xylulose-5-phosphate (Xu-5-P) in the hexose monophosphate shunt (HMS). Xu-5-P activates protein phosphatase 2A delta (PP2A delta) and dephosphorylates ChREBP*, which can then enter the nucleus and stimulate transcription by dimerizing with Mlx. On the other hand, insulin stimulates transcription of both <i>ChREBP</i> and <i>SREBP1c</i>. Although Xu-5-P has been proposed as the key regulator of ChREBP, glucose itself can activate ChREBP through its GRACE (glucose response activation conserved element) domain, by unkown mechanisms. ChREBP activity seems to be controlled mainly at the post-transcriptional level. </span><br />
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<span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;">Inhibition of ChREBP is mediated by phosphorylation of Ser196 (inactivating nuclear import) and Thr666 (preventing DNA binding) by PKA and AMPK. </span><br />
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<span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;">Target enzymes regulated by ChREBP include Liver Type Pyruvate Kinase (L-PK), the NADPH supply system (glucose-6-phosphate dehydrogenase, transketolase, malic enzyme, etc.), glucose 6 phosphatase (G6P), Acetyl CoA Carboxylase (ACC) and Fatty Acid Synthase (FAS). </span><br />
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<span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"><u>Studies with ChREBP knockout mice</u></span><br />
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<span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;">Iizuka et al (<a href="http://www.ncbi.nlm.nih.gov/pubmed/15118080?dopt=Abstract">1</a>) tested the importance of ChREBP for induction of several enzymes implicated in glycolysis, fatty acid synthesis and de novo lipogenesis.<i> ChREBP -/- </i>mice had slightly elevated glucose and insulin levels, deposited a large amount of glycogen in liver (but not in muscle), had almost half the plasma FFA of wild type (WT) mice and less adipose tissue, when fed a standard diet. Compared to WT mice, the level of LPK mRNA in </span><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"><i>ChREBP -/- </i>mice was only 27% of that measured in age-matched WT. ACL, ACC1 and FAS mRNA levels were also lower in KO mice. Levels of mRNA for <a href="http://www.biology-online.org/dictionary/Malic_enzyme">malic enzyme</a> showed the greatest reduction (59%). When mutant mice were fed a high-sucrose diet, plasma FFA were markedly reduced and mice experienced progressive hypothermia, culminating in death in less than 1 week (>50% of the </span><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"><i>ChREBP -/- </i>mice). When fed a high-fructose diet, they became moribund in a few days. This last observation was explained by low levels of fructokinase and triose kinase. </span><br />
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<span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;">To induce glycolysis and lipogenesis, they fed the mice a high starch diet. This diet increased levels of blood glucose compared to the standard diet, in both WT and KO mice. Plasma insulin in </span><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"><i>ChREBP -/- </i>mice fed the high starch diet was significantly higher than any other group. They were moderately insulin-resistant (assessed by glucose tolerance tests) and had 40% greater liver weights than WT (from increased glycogen storage). Despite having increased glucose and insulin levels, </span><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"><i>ChREBP -/- </i>mice</span><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"> fed the high starch diet showed reductions in liver mRNA for ACL, ACC1, FAS, malic enzyme, SCD-1 and LCE. This resulted in hepatic fatty acid synthesis rates that were 65% lower compared to WT. LPK remained lower in </span><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"><i>ChREBP -/- </i>mice even when fed the high starch diet, and Glut-2 mRNA was <10% of that measured in WT. Glucose 6-Pase and PEPCK were also reduced**. </span><br />
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<span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;">Inhibition of ChREBP expression in <i>ob/ob</i> mice <i>in vivo </i>using a RNA-interference technique improves hepatic steatosis by decreasing lipogenic rates, leading to decreased levels of triglycerides and NEFA, and improving insulin signaling in liver, skeletal muscle and white adipose tissue (<a href="http://www.ncbi.nlm.nih.gov/pubmed/16873678?dopt=Abstract">2</a>). Using a double mutant model (<i>ob/ob </i></span><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"><i>ChREBP -/-</i>) (leptin deficient-ChREBP deficient)</span><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;">, Iizuka et al (<a href="http://www.ncbi.nlm.nih.gov/pubmed/16705063?dopt=Abstract">3</a>) observed that inactivation of ChREBP expression reduced fat synthesis and obesity (body weight was very similar between </span><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"><i>ChREBP -/-</i>, WT and </span><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"><i>ob/ob </i></span><span class="Apple-style-span"><i><span style="font-family: 'Trebuchet MS', sans-serif;">ChREBP</span> -/-</i>)</span><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;">, and improved glucose tolerance and appetite control in </span><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"><i>ob/ob </i>mice. Thus, deletion of ChREBP was able to override some phenotypic characteristics of leptin-deficient mice. According to this, it has been suggested that reducing ChREBP might protect against beta-cell dysfunction in type 2 diabetes because it inhibits the expression of <i>Pdx-1</i>, <i>MafA</i>, <i>GcK</i> and <i>insulin</i> (<a href="http://www.ncbi.nlm.nih.gov/pubmed/20934404/">4</a>), as well as PPARa (<a href="http://www.ncbi.nlm.nih.gov/pubmed/21282101">5</a>). </span><br />
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<span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"><u>Pleiotropic properties of ChREBP</u></span><br />
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<span style="font-family: 'Trebuchet MS', sans-serif;">Although ChREBP is a key regulator of glycolysis, fatty acid synthesis, gluconeogenesis and de novo lipogenesis, it seems that it has other important roles. Yun-Seung et al (<a href="http://www.ncbi.nlm.nih.gov/pubmed/21811631">6</a>) tried to identify ChREBP target genes and gene expression patterns using ChIP-seq. They treated HepG2 cells with 25mM glucose for 8 hours. They found 783 target genes involved in different pathways. The most enriched pathway was lipid metabolism, followed by gluconeogenesis, as suspected. Nevertheless, there were other target genes that are associated with diverse functions, such as protein dimerization, embryonic development, among others. </span><br />
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<span style="font-family: 'Trebuchet MS', sans-serif;">One very intesting study was published by Tong et al (<a href="http://www.ncbi.nlm.nih.gov/pubmed/19995986?dopt=Abstract">7</a>). They investigated the role of ChREBP in cancer cell proliferation and metabolism using HCT116 colorectal cancer cells and HepG2 hebatoblastoma cells. It was seen that these cells require ChREBP to maintain their proliferative state and is rapidly upregulated upon growth factor stimulation. Moreover, comparison between HCT116 cells transfected with ChREBP siRNA and without transfection showed that inhibition of ChREBP caused a reduction in glucose uptake and lactate production, and increased oxygen consumption rates. This reflects increased mitochondrial respiration and decreased aerobic glycolysis. Transfected HCT116 cells also showed a reduction in glucose flux through the pentose phosphate pathway and de novo lipid biosynthesis. These observations were confirmed by 13C NMR. RNA microarray analysis of transfected cells showed an increase in the expression of p21, MDM2 and TIGAR, all of which are p53-dependent targets. Although the level of total p53 was the same in ChREBP deficient and non-deficient cells, the level of p53 that was phosphorylated in Ser-15 increased as ChREBP expression declined, effect that was explained by increased ROS concentrations. Supression of ChREBP resulted also in G1 and G2/M arrest. The authors finally showed that when injected to nude mice, ChREBP knockdown cells formed smaller tumors in vivo compared with control cells. </span><br />
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<span style="font-family: 'Trebuchet MS', sans-serif;"><u>Relevance to humans</u></span><br />
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<span style="font-family: 'Trebuchet MS', sans-serif;">Using animal studies to propose novel hypotheses can be fun. However, we cannot extrapolate findings directly. This is important when discussing metabolic pathways and the effect of different diets. For instance, mice have a basal metabolic rate that is 7 times greater than humans, so a 40% calorie restriction in mice mimics a therapeutic fasting in humans (<a href="http://www.ncbi.nlm.nih.gov/pubmed/16709251/">8</a>).There is evidence that mRNA levels of several lipogenic enzymes are different between rats and humans. In general, the lipogenic capacity of adipose tissue is lower in humans than rats, which may be explained by decreased ChREBP mRNA expression and lower abundance of SREBP1c </span><span style="font-family: 'Trebuchet MS', sans-serif;">(<a href="http://www.ncbi.nlm.nih.gov/pubmed/12897191?dopt=Abstract">9</a>)</span><span style="font-family: 'Trebuchet MS', sans-serif;">. But it is interesting to note that expression of ChREBP differs in adipose tissue and liver. In obese subjects, hepatic ChREBP expression increases while decreasing in adipose tissue, and there is a significant increase of ChREBP mRNA and protein levels during preadipocyte differentiation (<a href="http://www.ncbi.nlm.nih.gov/pubmed/21840420">10</a>). Differences between lean and obese subjects are shown below (A) in liver, omental and subcutaneous fat, as well as expression versus lean liver (considered as 1) </span><span style="font-family: 'Trebuchet MS', sans-serif;">(B)</span><span style="font-family: 'Trebuchet MS', sans-serif;">.</span><br />
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<div class="separator" style="clear: both; text-align: center;"><a href="http://2.bp.blogspot.com/-YWn1PWnUpUk/Tkr59fR2DMI/AAAAAAAAAFs/Jo0QYKifkB0/s1600/Chrebp.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="320" src="http://2.bp.blogspot.com/-YWn1PWnUpUk/Tkr59fR2DMI/AAAAAAAAAFs/Jo0QYKifkB0/s320/Chrebp.jpg" width="192" /></a></div><br />
<span style="font-family: 'Trebuchet MS', sans-serif;">We can see that lean people have less levels of ChREBP mRNA in liver, both have higher levels in both omental and subcutaneous adipose tissue. Because we know that we cant make conclusive statements only with mRNA levels (see <a href="http://www.ketotic.org/2011/08/of-chimps-and-men.html">here</a>), we must look at protein levels to see the full picture:</span><br />
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<div class="separator" style="clear: both; text-align: center;"><a href="http://2.bp.blogspot.com/-EZGxEg3hk1w/Tkr8IMoPTDI/AAAAAAAAAFw/-58gEFV43Z8/s1600/chrebp2.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="176" src="http://2.bp.blogspot.com/-EZGxEg3hk1w/Tkr8IMoPTDI/AAAAAAAAAFw/-58gEFV43Z8/s200/chrebp2.jpg" width="200" /></a></div><br />
<span style="font-family: 'Trebuchet MS', sans-serif;">Western Blot analysis of hepatic tissues of both lean and obese subjects (A) revealed the pressence of ChREBP (95 kDa) in obese but not in lean samples. Comparison to b-actin is shown in B. Protein concentration could not be detected in adipose tissue samples (indicating low absolute values and correlation between ChREBP mRNA and protein abundance). If there is a relevance for ChREBP and obesity-MetSyn in humans, we must look then at the liver, which is central to the disease. </span><br />
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<span style="font-family: 'Trebuchet MS', sans-serif;">We have seen in studies mentioned above that inhibition of ChREBP reduces hepatic steatosis, confirming the role of lipogenesis and de novo lipogenesis in the process. It is often stated that de novo lipogenesis is very low in humans and has no physiological relevance. I differ. It might be not relevant to adiposity directly, but indirectly by promoting hepatic insulin resistance and steatosis (<a href="http://www.ncbi.nlm.nih.gov/pubmed/15864343/">11</a>). M</span><span style="font-family: 'Trebuchet MS', sans-serif;">aybe this is why very low carbohydrate diets work very well treating NAFLD (<a href="http://www.ncbi.nlm.nih.gov/pubmed/16940371">12</a>,<a href="http://www.ncbi.nlm.nih.gov/pubmed/17219068">13</a>)</span><span style="font-family: 'Trebuchet MS', sans-serif;">, as hepatic DNL is increased with a high carbohydrate-low fat diet (<a href="http://www.ncbi.nlm.nih.gov/pubmed/12499321">14</a>). This should also amielorate hepatic insulin resistance and subsequently hyperglycemia, not only by decreasing dietary glucose, but by restoring hepatic insulin signaling. A high fat diet should also reduce ChREBP liver activity, thereby reducing hepatic steatosis (<a href="http://www.ncbi.nlm.nih.gov/pubmed/11724780">15</a>). </span><br />
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<span style="font-family: 'Trebuchet MS', sans-serif;"><u>Summing up</u></span><br />
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<span style="font-family: 'Trebuchet MS', sans-serif;">There is not much human research with ChREBP but until now, the evidence supports its importance in the pathogenesis of obesity and MetSyn. For me, it seems that a chronic high sugar diet could influence development of obesity and MetSyn by chronic stimulation of ChREBP. This creates an obsogenic environment in which lipids begin to accumulate in the liver, leading to loss of hepatic insulin signaling. ChREBP overexpression in beta-cells could also contribute to insulin resistance and diabetes onset. These effects could be further exacerbated by excessive fructose consumption, as fructose has been shown to increase ChREBP DNA binding (<a href="http://www.ncbi.nlm.nih.gov/pubmed/19799862">16</a>). This might explain why some high carbohydrate diets (ie. paleoish) do not cause obesity or MetSyn, compared with high sugar diets. Gut flora's effect on lipid metabolism and obesity might also include upregulating hepatic ChREBP, as shown with conventionalization of germ-free mice with normal microbiota from conventionally raised animals (<a href="http://www.ncbi.nlm.nih.gov/pubmed/15505215/">17</a>).<br />
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<span style="font-family: 'Trebuchet MS', sans-serif;">In conclusion, ChREBP might be the connection between high carbohydrate/sugar diets and obesity/MetSyn, as it promotes lipogenesis. This transcription factor directly links glucose/fructose to metabolic dysregulation and probably other "kind" of diseases, like cancer. The ability to improve the metabolic state of </span><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;"><i>ob/ob</i> mice suggests that a dietary treatment which reduces ChREBP activity should be the default treatment (at least initially) to MetSyn and leptin resistance. Especially when fructose seems to be the bioactive compound behind leptin resistance in a Western-type diet (<a href="http://www.ncbi.nlm.nih.gov/pubmed/21418711">18</a>). Moreover, this could explain why <u>maybe</u> a high carbohydrate diet can predispose to obesity. But as always, more research is needed. </span><br />
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<span style="font-family: 'Trebuchet MS', sans-serif;">* <a href="http://www.ncbi.nlm.nih.gov/pubmed/21835137">Recent research</a> points out to G6P as the relevant molecule for ChREBP activation.<br />
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<span style="font-family: 'Trebuchet MS', sans-serif;">** Which suggests that increased liver glycogen was not by gluconeogenesis. </span><br />
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<span style="float: left; padding-bottom: 5px; padding-left: 5px; padding-right: 5px; padding-top: 5px;"><a href="http://www.researchblogging.org/"><img alt="ResearchBlogging.org" src="http://www.researchblogging.org/public/citation_icons/rb2_large_white.png" style="border: 0;" /></a></span><span class="Z3988" title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.jtitle=Biochimica+et+biophysica+acta&rft_id=info%3Apmid%2F21840420&rfr_id=info%3Asid%2Fresearchblogging.org&rft.atitle=ChREBP+expression+in+the+liver%2C+adipose+tissue+and+differentiated+preadipocytes+in+human+obesity.&rft.issn=0006-3002&rft.date=2011&rft.volume=&rft.issue=&rft.spage=&rft.epage=&rft.artnum=&rft.au=Del+Pozo+CH&rft.au=Vesperinas-Garc%C3%ADa+G&rft.au=Rubio+MA&rft.au=Corripio-S%C3%A1nchez+R&rft.au=Torres-Garc%C3%ADa+AJ&rft.au=Obregon+MJ&rft.au=Calvo+RM&rfe_dat=bpr3.included=1;bpr3.tags=Health%2CBiology%2C+Nutrition">Del Pozo CH, Vesperinas-García G, Rubio MA, Corripio-Sánchez R, Torres-García AJ, Obregon MJ, & Calvo RM (2011). ChREBP expression in the liver, adipose tissue and differentiated preadipocytes in human obesity. <span style="font-style: italic;">Biochimica et biophysica acta</span> PMID: <a href="http://www.ncbi.nlm.nih.gov/pubmed/21840420" rev="review">21840420</a></span><br />
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<span class="Z3988" title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.jtitle=Endocrine+journal&rft_id=info%3Apmid%2F18490833&rfr_id=info%3Asid%2Fresearchblogging.org&rft.atitle=ChREBP%3A+a+glucose-activated+transcription+factor+involved+in+the+development+of+metabolic+syndrome.&rft.issn=0918-8959&rft.date=2008&rft.volume=55&rft.issue=4&rft.spage=617&rft.epage=24&rft.artnum=&rft.au=Iizuka+K&rft.au=Horikawa+Y&rfe_dat=bpr3.included=1;bpr3.tags=Biology%2CHealth">Iizuka K, & Horikawa Y (2008). ChREBP: a glucose-activated transcription factor involved in the development of metabolic syndrome. <span style="font-style: italic;">Endocrine journal, 55</span> (4), 617-24 PMID: <a href="http://www.ncbi.nlm.nih.gov/pubmed/18490833" rev="review">18490833</a></span>Unknownnoreply@blogger.com12tag:blogger.com,1999:blog-4724838399830873886.post-64796079847515256492011-08-10T22:45:00.001-07:002017-03-13T06:08:59.855-07:00Advanced cancer and the ketogenic diet<span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;">A new pilot trial about cancer-ketogenic diet has recently been published (<a href="http://www.ncbi.nlm.nih.gov/pubmed/21794124">1</a>).</span> <span style="font-family: 'Trebuchet MS', sans-serif;">This german group evaluated specifically the feasibility of a KD and its influence on the quality of life of patients with advanced metastatic tumors. The full text is free, so anyone can go and check the details and methodology used. The nutritional intervention was basically an <i>ad libitum </i>KD (<70g/CHO/day), plus extra omega-3 fatty acids. </span><br /><br /><span style="font-family: 'Trebuchet MS', sans-serif;">Dietary guidelines for the patients were (Table 2):</span><br /><ol><li><span style="font-family: 'Trebuchet MS', sans-serif;">Avoid all types of bread, cake, processed snacks, sweets, potatoes, pasta,<br />rice, polenta, vegetables rich in starch (corn, beans, peas) and cereals.</span></li><li><span style="font-family: 'Trebuchet MS', sans-serif;">Be aware of hidden sources of CHO in sugar sweetened drinks, candy,<br />chewing gum with sugar, milk and milk products, lunch meat and some<br />cheeses as well as in most “low fat” products.</span></li><li><span style="font-family: 'Trebuchet MS', sans-serif;">Fruits are rich in CHO, therefore always calculate the amount and select<br />those which are low in CHO.</span></li><li><span style="font-family: 'Trebuchet MS', sans-serif;">Vegetables are often rich in CHO - but mainly in dietary fiber, therefore<br />calculate the usable CHO only.</span></li><li><span style="font-family: 'Trebuchet MS', sans-serif;">If possible, prefer cold-water fish and meat from grazing cattle as protein<br />sources, because of their preferable fatty acid pattern.</span></li><li><span style="font-family: 'Trebuchet MS', sans-serif;">Vegetables and the few fruits allowed should be grown organic </span></li><li><span style="font-family: 'Trebuchet MS', sans-serif;"> As nibbles, select oil-rich nuts (walnuts, brazil nuts, macadamia nuts) and<br />seeds (sunflower), and only occasionally chocolate with very high cacao<br />content (min. 85%). </span></li></ol><span style="font-family: 'Trebuchet MS', sans-serif;">This guidelines look very paleoish to me (whatever that means). Some things I found interesting are points 5 and 6. Not seen emphasized commonly. Additionally, patients were told to drink two liquid meals as snacks. Components of this shake were provided to the patients and included: 250ml of highly fermented yogurt-drink, 8ml vegetable oil mixture and 10g of protein preparation. Ingredients of the components can be seen in Table 3. </span><br /><br /><span style="font-family: 'Trebuchet MS', sans-serif;">Because of problems with compliance to the diet, from 16 initial participants, only 5 remained until the end of the study (31%). Two patients dropped out during the first week, one because of inability to adhere to the diet and the other because of personal problems. Two patients died from their malignant disease during the study, one patient dropped out because he suffered excessive weight loss and weakness, one patient quit because he felt he wasnt able to stick to the dietary guidelines, one because resuming chemotherapy and four due to progress of their advanced cancer situation. The compliance problem is common. Adopting a ketogenic diet involves a lifestyle change. Something even advanced cancer patients can't do. This reminds me of a study in which some cancer patients wouldnt adopt a KD because that meant "giving up the candies and ice cream", despite the fact that it could improve their condition. To complicate things further, the acceptance of the diet varied greatly. One patient said that after 3 days on the diet it was not feasible at all and stopped the diet. Two patients rate feasibility as "very good", seven patients rate it "good", three "moderate" and one "poor". This was after 2 weeks of dieting so included the 16 initial participants. </span><br /><br /><span style="font-family: 'Trebuchet MS', sans-serif;">Quality of life was measured by the <a href="http://groups.eortc.be/qol/downloads/modules/specimen_20qlq_c30.pdf">EORTC QLQ-C30</a> questionnaire. Global scores remained relatively stable during the evaluation time. Physical and role functioning worsened slightly over time and constipation was reported by most patients. Because of the advanced cancer stage of the patients, fatigue, pain or dyspnoea increased over time. Nevertheless, emotional functioning increased slightly and insomina improved. </span><br /><br /><span style="font-family: 'Trebuchet MS', sans-serif;">Of those who completed the whole 12 weeks of dieting, 60% reached a stable ketonuria, predominantly being 1.5-4.0mM. Among blood parameters, only some patients had available data. Overall, CRP levels increased slighlty over time, considering the initial values were high. Two patients initially had elevated glucose, which returned to normal. In other patients, cholesterol levels were "normalized" (meant by reduced to conventionally accepted levels), as well as triglycerides in one patient and ALT in other patient. Total leukocyte count significantly increased during the intervention (even though one patient with initial low leukocyte counts showed a further reduction). </span><br /><br /><span style="font-family: 'Trebuchet MS', sans-serif;">Patients lost an average of 2kg. Progress of the disease occured in 5 patients who then discontinued the diet, while 5 patients who adhered to the diet had stable disease progression.</span><br /><br /><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;">Overall, the percentage of days in ketosis (>0.5mmol/l) was not correlated with the results of the study. We can see in table 4 that for example, patient 6 reached 97% of days in ketosis, but because of impaired food intake only completed 6 weeks and showed progress in the disease. On the other hand, patient 16 reached 100% days in ketosis, completed the trial and showed no progress in the disease. Both patients 5 and 11 only reached 25% of days in ketosis, but completed the trial and maintained their condition. </span><br /><br /><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;">The limitations of this study were:</span><br /><br /><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;">- Patients had advanced stage cancer. While a KD might help preventing and/or treating some cancers, there is no much left to do when the disease is too severe.</span><br /><br /><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;">- Most patients werent from the author's hospital. Blood samples and laboratory parameters had to be provided by their family doctors or local oncologists.</span><br /><br /><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;">- Short sample and short intervention time. </span><br /><br /><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;">Being fair, at the time the study was done (2007) guidelines to apply a KD for cancer treatment were scarce. The only premise was that reducing carbohydrates (hence sugar and cancer's fuel) would reduce progression of tumors. Since then, there is more information available which suggest how to implement the KD for these patients. Overall, evidence suggest that the diet should be not only ketogenic, but calorie restricted. This is for achieving low blood glucose levels and increased KB. In the study reviewed in this post, calories were <i>ad libitum</i> and with a carbohydrate intake limited to 70g/day. Glucose should be ideally around 55-65mg/dl and KB 4-7mM. Checking the study data, most patients had much higer BG (mean 93) and only mild ketosis. Therapeutic fasting is another valuable tool, but harder to comply with. Another factor to take into account is the cancer phenotype. A restricted KD should be more efficient in predominantely glucose-consuming tumors, which can be assessed using some phenotypic markers. Serum LDH levels, for instance, have been shown to be correlated with activation of HIF related genes (<a href="http://www.ncbi.nlm.nih.gov/pubmed/18086000">2</a>), which include glycolytic enzymes (<a href="http://www.ncbi.nlm.nih.gov/pubmed/19689405">3</a>). Or using the more conventional FDG-PET. Finally, utilization of gluconeogenesis and glycolysis inhibitors (ie. 2-Deoxyglucose or metformin) with the KD has also been proposed (<a href="http://www.ncbi.nlm.nih.gov/pubmed/21530093">4</a>,<a href="http://www.ncbi.nlm.nih.gov/pubmed/20656475">5</a>).</span><br /><br /><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;">Recent evidence suggests that this metabolic therapy is promising. One case report (<a href="http://www.ncbi.nlm.nih.gov/pubmed/20412570/">6</a>) has shown a rapid regression of glioblastoma multiforme in an old patient using the guidelines proposed by Seyfried et al (<a href="http://www.ncbi.nlm.nih.gov/pubmed/20804725">7</a>). This patient started the metabolic therapy with a water-only fast, switching then to a restricted KD which delivered 600kcal/day for 14 days. Dexamethasone was also eliminated (because high dosage steroid medication increases gluconeogenesis and blood glucose levels, while enhancing apoptosis resistance in tumor cells). Because of development of mild hiperuricemia, the KD was changed for a non-ketogenic calorie-restricted diet which also delivered 600kcal/day. Aside from the complete regression in such a short time (2-2.5 months), the most surprising finding in my opinion was the recurrence of the tumor after discontinuing the metabolic therapy, which strongly suggests that the therapy itself was the most infulential factor in cancer regression.</span><br /><br /><span class="Apple-style-span" style="font-family: 'Trebuchet MS', sans-serif;">It seems that controlling blood glucose levels is the more important part of the metabolic therapy. Achieving blood glucose levels of 55-65mg/dl and 4-7mM of ketone bodies has been termed as "the zone of metabolic management":</span><br /><br /><div class="separator" style="clear: both; text-align: center;"><a href="http://i56.tinypic.com/9q9v12.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="308" src="http://i56.tinypic.com/9q9v12.png" width="320" /></a></div><br /><span style="font-family: 'Trebuchet MS', sans-serif;">This resembles the results from the study on the GB patient: </span><br /><br /><div class="separator" style="clear: both; text-align: center;"><a href="http://2.bp.blogspot.com/-N2fUTP3Z7R8/TkNipN1pYxI/AAAAAAAAAFg/x-JxQPsAOts/s1600/GB.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="320" src="http://2.bp.blogspot.com/-N2fUTP3Z7R8/TkNipN1pYxI/AAAAAAAAAFg/x-JxQPsAOts/s320/GB.png" width="298" /></a></div><br /><span style="font-family: 'Trebuchet MS', sans-serif;">Although target blood glucose levels were not achieved, the reduction observed was sufficient for controlling disease progression. The other difference was the method of detection of ketosis, urinary ketones, which doesnt always correlate to blood ketone levels. </span><br /><br /><span style="float: left; padding-bottom: 5px; padding-left: 5px; padding-right: 5px; padding-top: 5px;"><a href="http://www.researchblogging.org/"><img alt="ResearchBlogging.org" src="http://www.researchblogging.org/public/citation_icons/rb2_large_white.png" style="border: 0;" /></a></span><span class="Z3988" title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.jtitle=Nutrition+%26+metabolism&rft_id=info%3Apmid%2F21794124&rfr_id=info%3Asid%2Fresearchblogging.org&rft.atitle=Effects+of+a+ketogenic+diet+on+the+quality+of+life+in+16+patients+with+advanced+cancer%3A+A+pilot+trial.&rft.issn=&rft.date=2011&rft.volume=8&rft.issue=1&rft.spage=54&rft.epage=&rft.artnum=&rft.au=Schmidt+M&rft.au=Pfetzer+N&rft.au=Schwab+M&rft.au=Strauss+I&rft.au=Kammerer+U&rfe_dat=bpr3.included=1;bpr3.tags=Health%2CBiology%2C+Nutrition">Schmidt M, Pfetzer N, Schwab M, Strauss I, & Kammerer U (2011). Effects of a ketogenic diet on the quality of life in 16 patients with advanced cancer: A pilot trial. <span style="font-style: italic;">Nutrition & metabolism, 8</span> (1) PMID: <a href="http://www.ncbi.nlm.nih.gov/pubmed/21794124" rev="review">21794124</a></span>Unknownnoreply@blogger.com15