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Nathan Goodyear

PLOS ONE: Microbial Dysbiosis in Colorectal Cancer (CRC) Patients - 0 views

  • differences in the colon microbiota in individuals with colon cancer versus those with a normal colonoscopy
  • qPCR revealed significant elevation of the Bacteroides/Prevotella population in cancer patients that appeared to be linked with elevated IL17 producing cells in the mucosa of individuals with cancer.
  • Bacteroides genus populations and more specifically those of Bacteroides fragilis, have recently been shown to produce a metalloprotease in colon cancer patients, but not in controls [12] suggesting this species sub population might favor carcinogenesis
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  • It is noteworthy that among the many mechanisms that may mediate associations between microbiota and human health [21]–[22], pro-inflammatory and immune cell activation in colon mucosa are of great importance in relation to malignancy
  • B. fragilis has been shown to induce mucosal regulatory T-cell responses in the intestine involving TH17 cell recruitment in experimental models
  • the elevations of Bacteroides in the stool and/or IL17 immunoreactive cells in the normal mucosa appear to be promising sensitive markers
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    A relationship between dysbiosis and colon cancer appears to be present.  Particularly an increase in Bacteroidetes and Prevotella species were found in those with colon cancer versus those without.  An inflammatory up regulation of IL-17 appears to be involved.  Whether this is a cause or effect is yet to be determined, but the presence of elevated Bacteroidetes species with increased IL17 could be used as sensitive biomarkers.
Nathan Goodyear

Tight Junctions, Intestinal Permeability, and Autoimmunity Celiac Disease and Type 1 Di... - 0 views

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    this study from 2009 showed how disrupted/imbalanced gut flora leads to leaky gut.  This case, high bacteroides relative to bifidobacterium and lactobacillus resulted in disruption of the zonulin pathway and thus lncreased intestinal permeability.
Nathan Goodyear

BMC Microbiology | Full text | The Firmicutes / Bacteroidetes ratio of the human microb... - 0 views

  • The microbiota of the large intestine plays an important role in host metabolism and maintenance of host health
  • Our results defining a standard adult profile, together with previous reports, showed that C. leptum, C. coccoides, Bacteroides and Bifidobacterium represent the four dominant groups of the adult fecal microbiota
  • Sub-dominant groups are Lactobacilli Enterobacteriaceae, Desulfovibrio, Sporomusa, Atopobium as well as other bacterial groups including Clostridium clusters XI, XIVb, and XVIII
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  • In infant fecal microbiota, we observed Bifidobacterium as the dominant group
  • this observation is strongly related to diet, being enhanced by breast feeding
  • Significant higher numbers of Bifidobacterium were observed in infants versus adults and seniors
  • the gastrointestinal tract is first colonized by facultative anaerobes, such as E. coli
  • Strict anaerobes, such as Clostridium, colonize at later stages, as can be seen by the relatively low levels of C. leptum and C. coccoides in infants
  • diet change must be considered among the primary causes for such a shift of microbiota between infants and adults.
  • In the case of elderly subjects, our qPCR results indicated a significant increase in the counts of E. coli when compared to adults. This data is consistent with other publications indicating that elderly subjects harbor a different E. coli microbiota profile compared to younger adults
  • a number of authors reported a reduction in the numbers and diversity of many protective commensal anaerobes, such as Bacteroides and Bifidobacteria
  • The Firmicutes to Bacteroidetes ratio was already shown to be of significant relevance in signaling human gut microbiota status
  • Our measurements of the Firmicutes/Bacteroidetes ratio in adults obtained by our species-specific qPCR are in agreement with those obtained by Ley et al
  • Compared with young adults, the elderly have a different digestive physiology, characterized at a physiological level by a reduction in transit and of digestive secretions
  • The Firmicutes/Bacteroidetes ratio undergoes an increase from birth to adulthood and is further altered with advanced age
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    Good discussion of the gut microbiome.  Age effects the gut bacteria balance.  The Firmicutes/Bacteroidetes ratio increases from young, to young adult, to the elderly in this study.  Is this simply a reflection of aging or is the a biomarker that can be changed through diet and targeted probiotics?
Nathan Goodyear

The Firmicutes/Bacteroidetes ratio of the human microbiota changes with age | BMC Micro... - 0 views

  • C. leptum, C. coccoides, Bacteroides and Bifidobacterium represent the four dominant groups of the adult fecal microbiota
  • Lactobacilli Enterobacteriaceae, Desulfovibrio, Sporomusa, Atopobium as well as other bacterial groups including Clostridium clusters XI, XIVb, and XVIII
  • The Firmicutes/Bacteroidetes ratio undergoes an increase from birth to adulthood and is further altered with advanced age
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    good review/discussion of gut microbiota, including the firmicutes:bacteroidetes ratio.
Nathan Goodyear

Normal Flora - Medical Microbiology - NCBI Bookshelf - 0 views

  • Concentrations of 109 to 1011 bacteria/g of contents are frequently found in human colon
  • more than 400 species have been identified
  • 95 to 99 percent belong to anaerobic genera such as Bacteroides, Bifidobacterium, Eubacterium, Peptostreptococcus, and Clostridium
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  • hese genera proliferate, occupy most available niches, and produce metabolic waste products such as acetic, butyric, and lactic acids
  • Anaerobic bacteria can then deconjugate bile acids in this region and bind available vitamin B12 so that the vitamin and fats are malabsorbed
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    normal flora of the body
Nathan Goodyear

Diet-Induced Dysbiosis of the Intestinal Microbiota and the Effects on Immunity and Dis... - 0 views

  • The gut microbiota participates in the body’s metabolism by affecting energy balance, glucose metabolism, and low-grade inflammation associated with obesity and related metabolic disorders
  • Firmicutes and Bacteroidetes represent the two largest phyla in the human and mouse microbiota and a shift in the ratio of these phyla has been associated with many disease conditions, including obesity
  • In obese humans, there is decreased abundance of Bacteroidetes compared to lean individuals
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  • weight loss in obese individuals results in an increase in the abundance of Bacteroidetes
  • there is conflicting evidence on the composition of the obese microbiota phenotype with regards to Bacteroidetes and Firmicutes ratios
  • Bifidobacteria spp. from the phyla Actinobacteria, has been shown to be depleted in both obese mice and human subjects
  • While it is not yet clear which specific microbes are inducing or preventing obesity, evidence suggests that the microbiota is a factor.
  • targeted manipulation of the microbiota results in divergent metabolic outcomes depending on the composition of the diet
  • The microbiota has been linked to insulin resistance or type 2 diabetes (T2D) via metabolic syndrome and indeed the microbiota of individuals with T2D is also characterized by an increased Bacteroidetes/Firmicutes ratio, as well as an increase in Bacillus and Lactobacillus spp
  • It was also observed that the ratio of Bacteriodes-Prevotella to C. coccoides-E. rectale positively correlated with glucose levels but did not correlate with body mass index [80]. This suggests that the microbiota may influence T2D in conjunction with or independently of obesity
  • In humans, high-fat Western-style diets fed to individuals over one month can induce a 71% increase in plasma levels of endotoxins, suggesting that endotoxemia may develop in individuals with GI barrier dyfunction connected to dysbiosis
  • LPS increases macrophage infiltration essential for systemic inflammation preceding insulin resistance, LPS alone does not impair glucose metabolism
  • early treatment of dysbiosis may slow down or prevent the epidemic of metabolic diseases and hence the corresponding lethal cardiovascular consequences
  • increased Firmicutes and decreased Bacteroidetes, which is the microbial profile found in lean phenotypes, along with an increase in Bifidobacteria spp. and Lactobacillus spp
  • mouse and rat models of T1D have been shown to have microbiota marked by decreased diversity and decreased Lactobacillus spp., as well as a decrease in the Firmicutes/Bacteroidetes ratio
  • microbial antigens through the innate immune system are involved in T1D progression
  • The microbiota appears to be essential in maintaining the Th17/Treg cell balance in intestinal tissues, mesenteric and pancreatic lymph nodes, and in developing insulitis, although progression to overt diabetes has not been shown to be controlled by the microbiota
  • There is evidence that dietary and microbial antigens independently influence T1D
  • Lactobacillus johnsonii N6.2 protects BB-rats from T1D by mediating intestinal barrier function and inflammation [101,102] and a combination probiotic VSL#3 has been shown to attenuate insulitis and diabetes in NOD mice
  • breast fed infants have higher levels of Bifidobacteria spp. while formula fed infants have higher levels of Bacteroides spp., as well as increased Clostridium coccoides and Lactobacillus spp
  • the composition of the gut microbiota strongly correlates with diet
  • In mice fed a diet high in fat, there are many key gut population changes, such as the absence of gut barrier-protecting Bifidobacteria spp
  • diet has a dominating role in shaping gut microbiota and changing key populations may transform healthy gut microbiota into a disease-inducing entity
  • “Western” diet, which is high in sugar and fat, causes dysbiosis which affects both host GI tract metabolism and immune homeostasis
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    Nice discussion of how diet, induces gut bacterial change, that leads to metabolic endotoxemia and disease.
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