Microbial interactions with the intestinal epithelium and beyond: Focusing on immune cell maturation and homeostasis.

Microbial metabolites influence the function of epithelial, endothelial and immune cells in the intestinal mucosa. Microbial metabolites like SCFAs and B complex vitamins direct macrophage polarization whereas microbial derived biogenic amines modulate intestinal epithelium and immune response. Aberrant bacterial lipopolysaccharide-mediated signaling may be involved in the pathogenesis of chronic intestinal inflammation and colorectal carcinogenesis. Our perception of human microbes has changed from that of opportunistic pathogens to active participants maintaining intestinal and whole body homeostasis. This review attempts to explain the dynamic and enriched interactions between the intestinal epithelial mucosa and commensal bacteria in homeostasis maintenance.