Understanding How Commensal Obligate Anaerobic Bacteria Regulate Immune Functions in the Large Intestine

The health of humans is impacted by the symbiotic relationship with their microbiota, while a dysbiosis of the resident microbiota is associated with various disorders, such as inflammatory bowel diseases [1–3], colorectal cancer [4,5], coeliac disease [6] and obesity [7]. The intestinal mucosa is in intimate contact with  commensal  microorganisms  and  food  antigens  but  also  faces  the  constant  risk  of  infection  by pathogens from the external environment. The challenging task for the intestinal immune system is to maintain  a  homeostatic  balance  between  tolerance  towards  harmless  agents  and  immunity  against pathogens.  This  is  achieved  through  various  regulatory  adaptations  in  the  cross-talk  between  the commensal bacteria, intestinal epithelial cells (IECs) and immune cells of the GIT.