Intestinal Ralstonia pickettii augments glucose intolerance in obesity

An altered intestinal microbiota composition has been implicated in the pathogenesis of metabolic disease including obesity and type 2 diabetes mellitus (T2DM). Low grade inflammation, potentially initiated by the intestinal microbiota, has been suggested to be a driving force in the development of insulin resistance in obesity. Here, we report that bacterial DNA is present in mesenteric adipose tissue of obese but otherwise healthy human subjects. Pyrosequencing of bacterial 16S rRNA genes revealed that DNA from the Gram-negative species Ralstonia was most prevalent. Interestingly, fecal abundance of Ralstonia pickettii was increased in obese subjects with pre-diabetes and T2DM. To assess if R. pickettii was causally involved in development of obesity and T2DM, we performed a proof-of-concept study in diet-induced obese (DIO) mice. Compared to vehicle-treated control mice, R. pickettii-treated DIO mice had reduced glucose tolerance. In addition, circulating levels of endotoxin were increased in R. pickettii-treated mice. In conclusion, this study suggests that intestinal Ralstonia is increased in obese human subjects with T2DM and reciprocally worsens glucose tolerance in DIO mice.Peer reviewe

Data from: Intestinal Ralstonia pickettii augments glucose intolerance in obesity

An altered intestinal microbiota composition has been implicated in the pathogenesis of metabolic disease including obesity and type 2 diabetes mellitus (T2DM). Low grade inflammation, potentially initiated by the intestinal microbiota, has been suggested to be a driving force in the development of insulin resistance in obesity. Here, we report that bacterial DNA is present in mesenteric adipose tissue of obese but otherwise healthy human subjects. Pyrosequencing of bacterial 16S rRNA genes revealed that DNA from the Gram-negative species Ralstonia was most prevalent. Interestingly, fecal abundance of Ralstonia pickettii was increased in obese subjects with pre-diabetes and T2DM. To assess if R. pickettii was causally involved in development of obesity and T2DM, we performed a proof-of-concept study in diet-induced obese (DIO) mice. Compared to vehicle-treated control mice, R. pickettii-treated DIO mice had reduced glucose tolerance. In addition, circulating levels of endotoxin were increased in R. pickettii-treated mice. In conclusion, this study suggests that intestinal Ralstonia is increased in obese human subjects with T2DM and reciprocally worsens glucose tolerance in DIO mice

Data from: Intestinal Ralstonia pickettii augments glucose intolerance in obesity

An altered intestinal microbiota composition has been implicated in the pathogenesis of metabolic disease including obesity and type 2 diabetes mellitus (T2DM). Low grade inflammation, potentially initiated by the intestinal microbiota, has been suggested to be a driving force in the development of insulin resistance in obesity. Here, we report that bacterial DNA is present in mesenteric adipose tissue of obese but otherwise healthy human subjects. Pyrosequencing of bacterial 16S rRNA genes revealed that DNA from the Gram-negative species Ralstonia was most prevalent. Interestingly, fecal abundance of Ralstonia pickettii was increased in obese subjects with pre-diabetes and T2DM. To assess if R. pickettii was causally involved in development of obesity and T2DM, we performed a proof-of-concept study in diet-induced obese (DIO) mice. Compared to vehicle-treated control mice, R. pickettii-treated DIO mice had reduced glucose tolerance. In addition, circulating levels of endotoxin were increased in R. pickettii-treated mice. In conclusion, this study suggests that intestinal Ralstonia is increased in obese human subjects with T2DM and reciprocally worsens glucose tolerance in DIO mice

Dietary components of the HFD.

<p>Dietary components of the HFD.</p

<i>Ralstonia pickettii</i> levels correlate with insulin resistance and T2DM in obese subjects.

<p>(A) Bacterial DNA is present in mesenteric-visceral adipose tissue from otherwise healthy obese subjects that underwent laparoscopic surgery. Each lane depicts bacterial amplicons in a single mesenteric adipose tissue specimen of a subset of 6 patients. Arrow depicts the dominant amplicon of <i>Ralstonia</i> spp. as identified by Sanger sequencing of isolated bands. M = standard. (B) Pyrosequencing revealed presence of different species (percentage of total bacterial DNA) in human mesenteric visceral adipose tissue specimen (n = 12 subjects) with <i>Ralstonia</i> spp. being the most abundant Gram-negative bacteria. (C) Fecal 16S rRNA <i>R</i>. <i>pickettii</i> levels in obese postmenopausal women with normal glucose tolerance (NGT) (n = 42), impaired glucose tolerance (IGT) (n = 45) and type 2 diabetes mellitus (T2DM) (n = 47). (D) Correlation between fecal <i>R</i>. <i>pickettii</i> and plasma adiponectin in obese postmenopausal women with NGT, IGT and T2DM (population mixed in this figure). Error bars are represented as mean ± SEM. Mann-Whitney U testing (two sided) was performed to analyze the difference between clinical groups (C) and Spearman rank test (two sided) was used to calculate correlation coefficients (D). P-values < 0.05 (indicated by *) were considered statistically significant (using GraphPad Prism 5.1 and SPSS).</p

<i>Ralstonia pickettii</i> supplementation reduces glucose tolerance and augments inflammatory tone in DIO mice.

<p>(A) Oral glucose tolerance testing (OGTT) revealed that (HI)-<i>R</i>. <i>pickettii</i> treatment decreased glucose tolerance compared to glycerol treatment in DIO-mice. Area under the curve (AUC) is represented in the insert. (B) Plasma endotoxin levels (EU/ml) were increased in <i>R</i>. <i>pickettii</i>-treated mice compared with glycerol and HI <i>R</i>. <i>pickettii</i>-treated counterparts. (C) Relative mRNA expression of <i>Tlr1</i>, <i>Tlr2</i>, <i>Tlr4</i>, <i>Tlr5</i>, <i>IL1B</i>, <i>IL10</i>, <i>TNFα</i>, <i>F4/80</i>, <i>CD68</i> and <i>IFNγ</i> in mesenteric white adipose tissue (mWAT) of mice treated with glycerol, HI <i>R</i>. <i>pickettii</i> and <i>R</i>. <i>pickettii</i>. Gene expression was normalized using <i>36B4</i> as a housekeeping gene. N = 10 mice per group. Error bars are represented as mean ± SEM; p values were determined by Mann-Whitney U test or two-way ANOVA testing with Bonferroni post-test for multiple-comparison analysis (for OGTT). P-values < 0.05 (indicated by *) or < 0.01 (indicated by **) were considered statistically significant (using GraphPad Prism 5.1 and SPSS).</p