The Role of Gut Microbiota in Gastrointestinal Immune Homeostasis and Inflammation: Implications for Inflammatory Bowel Disease

Inflammatory bowel disease (IBD), a heterogeneous group of recurring inflammatory conditions of the digestive system that encompass both ulcerative colitis (UC) and Crohn’s disease (CD), pose a significant public health challenge, currently lacking a definitive cure. The specific etiopathogenesis of IBD is not yet fully understood, but a multifactorial interplay of genetic and environmental factors is suspected. A growing body of evidence supports the involvement of intestinal dysbiosis in the development of IBD, including the effects of dysbiosis on the integrity of the intestinal epithelial barrier, modulation of the host immune system, alterations in the enteric nervous system, and the perpetuation of chronic inflammation. A comprehensive understanding of these mechanisms is important to define preventive measures, to develop new effective and lasting treatments, and to improve disease outcome. This review examines the complex tri-directional relationship between gut microbiota, mucosal immune system, and intestinal epithelium in IBD. In addition, nonpharmacological and behavioral strategies aimed at restoring a proper microbial–immune relationship will be suggested.