Gut Microbiome and Regulation of Mucosal Immunity

Abstract

A large number of microorganisms, such as bacteria and fungi, coexist in the digestive tract and they play an essential role in the maintenance of homeostasis in the body. Gut microbiota in the gastrointestinal tract affect the host cells directly or indirectly through their metabolites. They also support the development of the host immune system and modify functions of the host. Bacteria coexist not only in the gastrointestinal lumen but also inside mucosa-associated lymphoid tissue (MALT), such as Peyer’s patches of the small intestine which have also been shown to affect the immune function of the host. Dietary components can alter the composition of intestinal flora and affect the gastrointestinal mucosal barrier and host immune function. Intestinal bacteria, the host-immune system, and diet influence each other to create and maintain homeostasis, and they also have critical roles in various pathological conditions. Molecules modified by glycosylation and metabolites produced by bacteria such as short-chain fatty acids act as mediators between host cells and microorganisms, playing a major role in determining the composition of gut microorganisms as well as mediating biological functions of the host.