Project description:Gut microbiota dysbiosis characterizes systemic metabolic alteration, yet its causality is debated. To address this issue, we transplanted antibiotic-free conventional wild-type mice with either dysbiotic (“obese”) or eubiotic (“lean”) gut microbiota and fed them either a NC or a 72%HFD. We report that, on NC, obese gut microbiota transplantation reduces hepatic gluconeogenesis with decreased hepatic PEPCK activity, compared to non-transplanted mice. Of note, this phenotype is blunted in conventional NOD2KO mice. By contrast, lean microbiota transplantation did not affect hepatic gluconeogenesis. In addition, obese microbiota transplantation changed both gut microbiota and microbiome of recipient mice. Interestingly, hepatic gluconeogenesis, PEPCK and G6Pase activity were reduced even once mice transplanted with the obese gut microbiota were fed a 72%HFD, together with reduced fed glycaemia and adiposity compared to non-transplanted mice. Notably, changes in gut microbiota and microbiome induced by the transplantation were still detectable on 72%HFD. Finally, we report that obese gut microbiota transplantation may impact on hepatic metabolism and even prevent HFD-increased hepatic gluconeogenesis. Our findings may provide a new vision of gut microbiota dysbiosis, useful for a better understanding of the aetiology of metabolic diseases. all livers are from NC-fed mice only.
Project description:Bariatric surgery is associated with improved breast cancer (BC) outcomes, including greater immunotherapy effectiveness in a pre-clinical BC model. A potential mechanism of bariatric surgery-associated protection is through the gut microbiota. Here, we demonstrate the dependency of improved immunotherapy response on the post-bariatric surgery gut microbiome via fecal microbial transplant. Cecal contents were isolated from either obese controls that received sham surgery or formerly obese mice following bariatric surgery-induced weight loss and transferred by FMT to lean recipients. Response to αPD-1 immunotherapy was significantly improved following FMT from formerly obese bariatric-surgery treated mice. Microbes can impact tumor burden through microbially derived metabolites produced or modified by gut microbiota including branched chain amino acids (BCAA). Circulating BCAA correlated significantly with NK T cell content in the tumor microenvironment in both donor mice after bariatric surgery and in FMT recipients of donor cecal content after bariatric surgery compared to obese sham controls. Findings implicate a role of microbially-derived BCAA in activating anti-tumor immunity that is dependent upon bariatric surgery. Importantly, when stool from a patient who exhibited 25% weight loss post-bariatric surgery was transplanted into recipient mice and compared to the patient’s pre-bariatric surgery stool transplant. Patient samples post bariatric surgery significantly reduced tumor burden by 2.4-fold and immunotherapy effectiveness was doubled. Taken together, findings suggest that reinvigorating anti-tumor immunity may be dependent upon microbially derived metabolites such as BCAA.
Project description:Obesity is a risk factor for Osteoarthritis (OA), the greatest cause of disability in the US. The impact of obesity on OA is driven by systemic inflammation, now understood to be caused by an altered gut microbiome. Oligofructose, a non-digestible prebiotic fiber, can correct the obese gut microbiome, suggesting a novel approach to treat the OA of obesity. Here we report that in the obese murine gut, beneficial Bifidobacteria are lost while key proinflammatory species gain in abundance. A downstream systemic inflammatory signature culminates with accelerated knee OA. Oligofructose supplementation corrects the obese gut microbiome in part by supporting key commensal microflora, particularly Bifidobacterium pseudolongum. This leads to reduced inflammation in the colon, circulation and knee, and protection from OA. This novel recognition of a gut microbiome-OA connection sets the stage for discovery of new OA therapeutics targeting specific microbes inhabiting the intestinal space to inhibit disease pathology.
Project description:Gut microbiome research is rapidly moving towards the functional characterization of the microbiota by means of shotgun meta-omics. Here, we selected a cohort of healthy subjects from an indigenous and monitored Sardinian population to analyze their gut microbiota using both shotgun metagenomics and shotgun metaproteomics. We found a considerable divergence between genetic potential and functional activity of the human healthy gut microbiota, in spite of a quite comparable taxonomic structure revealed by the two approaches. Investigation of inter-individual variability of taxonomic features revealed Bacteroides and Akkermansia as remarkably conserved and variable in abundance within the population, respectively. Firmicutes-driven butyrogenesis (mainly due to Faecalibacterium spp.) was shown to be the functional activity with the higher expression rate and the lower inter-individual variability in the study cohort, highlighting the key importance of the biosynthesis of this microbial by-product for the gut homeostasis. The taxon-specific contribution to functional activities and metabolic tasks was also examined, giving insights into the peculiar role of several gut microbiota members in carbohydrate metabolism (including polysaccharide degradation, glycan transport, glycolysis and short-chain fatty acid production). In conclusion, our results provide useful indications regarding the main functions actively exerted by the gut microbiota members of a healthy human cohort, and support metaproteomics as a valuable approach to investigate the functional role of the gut microbiota in health and disease.