Search bioRxiv⌕ Search

Biology subjects

Bretin, A.

Publications and source records attributed to Bretin, A..

2 recordsLinked to original sources

PSYLLIUM FIBER PROTECTS MICE AGAINST WESTERN DIET-INDUCED METABOLIC SYNDROME VIA MICROBIOTA-DEPENDENT MECHANISM

We sought to identify semi-purified fibers that broadly promote gut and metabolic health and, moreover, identify the mechanisms by which they do so. Screening an array of purified fibers led us o appreciate that, of all fibers tested, psyllium was unique in that it strongly protected mice against both colitis and metabolic syndrome. Further investigation led us to appreciate that psylliums mechanism of action is quite distinct. Specifically, data we report in a manuscript under review indicates that low doses of psyllium protect mice against colitis via increasing serum bile acids that activate FXR. Here, we report that higher doses of psyllium protect mice against diet-induced obesity/metabolic syndrome by a FXR-independent mechanism that requires presence of at least a minimal microbiota.

microbiology↗

Sphingolipid production by gut Bacteroidetes regulates glucose homeostasis

Levels of Bacteroidetes in the gut microbiome are positively associated with insulin resistance (IR) in humans. Considering that IR is promoted by elevations in hepatic sphingolipids (SL), particularly ceramides, and that Bacteroidetes are the only microbiome phylum possessing genes encoding serine palmitoyltransferase (SPT), which mediates SL synthesis, we investigated a potential link between bacterial SL production, host SL metabolism, and IR. In vitro, bacterial SLs entered colonocytes and were metabolized into complex SL, including ceramides. In mice, administration of WT Bacteroides thetaiotaomicron, but not a SPT-deficient mutant, resulted in elevated levels of liver ceramides and reduced responsiveness to exogenously administered insulin. This work establishes bacterial SLs as a new class of microbiome-derived molecule capable of impacting host metabolism.\n\nOne Sentence SummarySL production by gut Bacteroidetes regulates liver ceramide levels and insulin sensitivity.

microbiology↗