Scientific Publications
Regulation of enteroendocrine cell networks by the major human gut symbiont Bacteroides thetaiotaomicron
Frontiers in Microbiology, Unknown
Gut microbes have critical roles in maintaining host physiology, but their effects on epithelial chemosensory enteroendocrine cells (EEC) remain unclear. We investigated the role that the ubiquitous commensal gut bacterium Bacteriodes thetaiotaomicron (Bt) and its major fermentation products, acetate, propionate, and succinate (APS), have in shaping EEC networks in the murine gastrointestinal tract (GIT). The distribution and numbers of EEC populations were assessed in tissues along the GIT by fluorescent immunohistochemistry in specific pathogen free (SPF), germfree (GF) mice, GF mice conventionalized by Bt or Lactobacillus reuteri (Lr), and GF mice administered APS. GF mice up-regulated their EEC network, in terms of a general EEC marker chromogranin A (ChrA) expression, numbers of serotonin-producing enterochromaffin cells, and both hormone-producing K- and L-cells, with a corresponding increase in serum glucagon-like peptide-1 (GLP-1) levels. Bt conventionalization restored EEC numbers to levels in SPF mice with regional specificity; the effects on ChrA and L-cells were mainly in the small intestine, the effects on K-cells and EC cells were most apparent in the colon. By contrast, Lr did not restore EEC networks in conventionalized GF mice. Administration of APS mimicked to a large extent the effects of Bt in GF mice. After withdrawal of APS, the changes in EEC were maintained and, in some cases, greater than during APS treatment. This data provides evidence of microbiota influences on regulating EEC networks, with a single microbe, Bt, recapitulating its role in a process that may be dependent upon its fermentation products.
Frontiers in Microbiology, Unknown
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