Slimy partners: the mucus barrier and gut microbiome in ulcerative colitis

Ulcerative colitis (UC) is a chronic recurrent intestinal inflammatory disease characterized by high incidence and young onset age. Recently, there have been some interesting findings in the pathogenesis of UC. The mucus barrier, which is composed of a mucin complex rich in O-glycosylation, not only provides nutrients and habitat for intestinal microbes but also orchestrates the taming of germs. In turn, the gut microbiota modulates the production and secretion of mucins and stratification of the mucus layers. Active bidirectional communication between the microbiota and its ‘slimy’ partner, the mucus barrier, seems to be a continually performed concerto, maintaining homeostasis of the gut ecological microenvironment. Any abnormalities may induce a disorder in the gut community, thereby causing inflammatory damage. Our review mainly focuses on the complicated communication between the mucus barrier and gut microbiome to explore a promising new avenue for UC therapy. Gut microbiome: Slimy symbiosis Gaining a better understanding of the bidirectional communication between the gut microbiome and the colon’s mucus layer, which covers and protects intestinal tissue, could aid in developing effective treatments for ulcerative colitis (UC). Increasing evidence links gut microbiome imbalance to UC, a form of inflammatory bowel disease. Xiaohong Zhang at Ningbo University in China and co-workers have reviewed gut microbiome–mucus layer interactions. They report that the mucus layer, comprised of a firm sterile inner layer, and a loose, densely colonized outer layer, nourishes and provides a home for ‘good’ microbes, while excluding pathogens. In turn, good microbes promote mucus layer production and stratification. Without adequate dietary fiber, gut microbes over-consume the mucus layer, exposing intestinal tissue and causing inflammation. This article provides clue for investigating treatments for inflammatory bowel diseases, including UC.