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.
Project description:Gut microbiota-derived peptidoglycan fragments (PGNs) are key signaling molecules that regulate multiple aspects of the host’s health. Yet the exact structures of natural PGNs in hosts have not been fully elucidated. Herein, we developed an LC-HRMS/MS analytical platform for global quantification and profiling of natural PGN subtypes in host gut and sera, unexpectedly revealing the abundance of PGN-derived saccharide moieties that do not resemble canonical ligands of mammalian NOD1/2 receptors. Focusing on the disaccharide GlcNAc-MurNAc (GM), which does not activate NOD1/2 yet still exhibits immunostimulatory effects in host immune cells, we established GM as a mild TLR4 agonist, illustrating an alternate PGN sensing mechanism other than NOD signaling. Importantly, the administration of GM mitigates colonic inflammation in the DSS-induced colitis model in mice via a TLR4-dependent manner, highlighting the in vivo significance of gut microbiota-derived PGN saccharides in maintaining host intestinal homeostasis.
Project description:In the presented study, in order to unravel gut microbial community multiplicity and the influence of maternal milk nutrients (i.e., IgA) on gut mucosal microbiota onset and shaping, a mouse GM (MGM) was used as newborn study model to discuss genetic background and feeding modulation on gut microbiota in term of symbiosis, dysbiosis and rebiosis maintenance during early gut microbiota onset and programming after birth. Particularly, a bottom-up shotgun metaproteomic approach, combined with a computational pipeline, has been compred with a culturomics analysis of mouse gut microbiota, obtained by MALDI-TOF mass spectrometry (MS).
Project description:The gut microbiota, immune system, and enteric nervous system interact to regulate adult gut physiology. Yet the mechanisms establishing gut physiology during development remain unknown. We report that in developing zebrafish, enteroendocrine cells produced IL-22 in response to microbial signals before lymphocytes populate the gut. In larvae, IL-22 shaped the gut microbiota, increased Lactobacillaceae abundance and ghrelin expression to promote gut motility. Impaired motility and ghrelin expression were restored in il22-/- zebrafish by transfer of microbiota from wild-type zebrafish or by monoassociation with Lactobacillus plantarum. IL-22-deficient mice had impaired gut motility and reduced ghrelin expression in early life too, indicating a conserved function. Thus, before immune system maturation, enteroendocrine cells regulate early-life gut function by controlling the microbiota via IL-22.
Project description:We have previously demonstrated that the gut microbiota can play a role in the pathogenesis of conditions associated with exposure to environmental pollutants. It is well accepted that diets high in fermentable fibers such as inulin can beneficially modulate the gut microbiota and lessen the severity of pro-inflammatory diseases. Therefore, we aimed to test the hypothesis that hyperlipidemic mice fed a diet enriched with inulin would be protected from the pro-inflammatory toxic effects of PCB 126.
Project description:Gut microbiota are known to influence oral drug disposition, yet the specific host pathways they affect remain poorly characterized. This study provides a transcriptome-wide characterization of how physiological gut microbiota regulate the expression of intestinal transporters, phase I and phase II metabolic enzymes, and barrier machinery relevant to oral drug disposition. By identifying microbiota-responsive processes, this work defines the scope of inter-individual variability attributable to gut microbial effects.
Project description:Here we exploited a Han Chinese population-based cohort with extensive host metadata established in the Pinggu (PG) district of Beijing, and investigated gut microbiota from 2,338 adults (26-76 years) by metagenomic sequencing, revealing associations of the gut microbiota with sex, sex hormones, age, and a number of clinical and metabolic parameters.