Project description:Specific gut microbiota is critically involved in metabolic diseases, including obesity. Through analysis of gut microbiota in diabetic patients and animal models, it was found that Romboutsia ilealis is closely associated with obesity. Here, our findings show that oral administration of Romboutsia ilealis significantly alleviates diet-induced obesity and metabolic dysfunction. Interestingly, this effect occurs not through modulation of food intake or energy expenditure, but by regulating lipid absorption and metabolism in the gut. Additionally, metabolomics analysis identified 2-oxindole-3-acetic acid (OAA) as the key metabolite involved in the regulation of obesity by Romboutsia ilealis. Its regulatory effect on intestinal lipid absorption was further validated both in vitro and in vivo. Mechanistically, using biotin-labeled OAA combined with proteomic analysis, we found that OAA directly interacts with the deubiquitin enzyme PSMD3, increasing the ubiquitination level of m6A binding protein YTHDF2 and reducing its protein stability, thereby enhancing intestinal lipid absorption. Furtherly, through m6A-seq, we discovered that YTHDF2 negatively regulates the expression of RXRB by recognizing the m6A sites on its mRNA, which in turn downregulates the expression of lipid absorption and transport proteins CD36 and FABP2, ultimately inhibiting intestinal lipid absorption. In summary, our findings reveal that Romboutsia ilealis and OAA regulate obesity-associated lipid accumulation through PSMD3-mediated deubiquitination of YTHDF2, suggesting that they represent novel prebiotics and probiotics with potential as therapeutic agents against obesity.
Project description:It has been reported that Cryptosporidium parvum, a species of a protozoan frequently isolated from humans and animals, is able to induce digestive adenocarcinoma in a rodent model. Consistently, some epidemiological studies have reported an association with cryptosporidiosis in patients with colorectal adenocarcinoma. However, the correlation between cryptosporidiosis and human digestive cancer remains unclear at this time, and it is not known whether this intracellular parasite, considered an opportunistic agent, is able to induce gastrointestinal malignancies in humans. In order to add new arguments for a probable association between cryptosporidiosis and digestive human cancer, the main aim of this study is to determine prevalence and to identify species of Cryptosporidium among a French digestive cancer population.
Project description:Trimethylamine (TMA) is an important gut microbial metabolite strongly associated with human disease. There are prominent gaps in our understanding of how TMA is produced from the essential dietary nutrient L-carnitine, particularly in the anoxic environment of the human gut where oxygen-dependent L-carnitine-metabolizing enzymes are likely inactive. Here, we elucidate the chemical and genetic basis for anaerobic TMA generation from the L-carnitine-derived metabolite γ-butyrobetaine (γbb) by the human gut bacterium Emergencia timonensis. We identify a set of genes upregulated by γbb and demonstrate that the enzymes encoded by the induced γbb utilization (bbu) gene cluster convert γbb to TMA. The key TMA-generating step is catalyzed by a previously unknown type of TMA-lyase enzyme that utilizes a flavin cofactor to catalyze a redox neutral transformation. We identify additional cultured and uncultured host-associated bacteria that possess the bbu gene cluster, providing insights into the distribution of anaerobic γbb metabolism. Lastly, we present genetic, transcriptional, and metabolomic evidence that confirms the relevance of this metabolic pathway in the human gut microbiota. These analyses indicate that the anaerobic pathway is a more substantial contributor to TMA generation from L-carnitine in the human gut than the previously proposed aerobic pathway. The discovery and characterization of the bbu pathway provides the critical missing link in anaerobic metabolism of L-carnitine to TMA, enabling investigation into the connection between this microbial function and human disease.
Project description:The indigenous human gut microbiota is a major contributor to the human superorganism with established roles in modulating nutritional status, immunity, and systemic health including diabetes and obesity. The complexity of the gut microbiota consisting of over 1012 residents and approximately 1000 species has thus far eluded systematic analyses of the precise effects of individual microbial residents on human health. In contrast, health benefits have been shown upon ingestion of certain so-called probiotic Lactobacillus strains in food products and nutritional supplements, thereby providing a unique opportunity to study the global responses of a gut-adapted microorganism in the human gut and to identify the molecular mechanisms underlying microbial modulation of intestinal physiology, which might involve alterations in the intestinal physico-chemical environment, modifications in the gut microbiota, and/or direct interaction with mucosal epithelia and immune cells. Here we show by transcriptome analysis using DNA microarrays that the established probiotic bacterium, L. plantarum 299v, adapts its metabolic capacity in the human digestive tract for carbohydrate acquisition and expression of exo-polysaccharide and proteinaceous cell surface compounds. This report constitutes the first application of global gene expression profiling of a gut-adapted commensal microorganism in the human gut. Comparisons of the transcript profiles to those obtained for L. plantarum WCFS1 in germ-free mice revealed conserved L. plantarum responses indicative of a core transcriptome expressed in the mammalian gut and provide new molecular targets for determining microbial-host interactions affecting human health. Hybridization of the samples against a common reference of gDNA isolated from L. plantarum 299v
Project description:Emerging evidences have shown that gut microbiota have played roles in the modulation of chemotherapy agents for cancer patients receiving chemotherapy. Probiotics are gut microbiota beneficial to human body. However, little was known about the role of probiotics for cancer patients receiving chemotherapy. Lactobacillus rhamnosus TCELL-1 is a kind of probiotics which were isolated from the gut mucosa of healthy Taiwanese. The aim of the study was to evaluate the effect of Lactobacillus rhamnosus TCELL-1 upon staged III colorectal cancer patients receiving adjuvant chemotherapy.