title: Maintenance of gut homeostasis by the mucosal immune system.
abstract: Inflammatory bowel diseases (IBD) are represented by ulcerative colitis (UC) and Crohn's disease (CD), both of which involve chronic intestinal inflammation. Recent evidence has indicated that gut immunological homeostasis is maintained by the interaction between host immunity and intestinal microbiota. A variety of innate immune cells promote or suppress T cell differentiation and activation in response to intestinal bacteria or their metabolites. Some commensal bacteria species or bacterial metabolites enhance or repress host immunity by inducing T helper (Th) 17 cells or regulatory T cells. Intestinal epithelial cells between host immune cells and intestinal microbiota contribute to the separation of these populations and modulate host immune responses to intestinal microbiota. Therefore, the imbalance between host immunity and intestinal microbiota caused by host genetic predisposition or abnormal environmental factors promote susceptibility to intestinal inflammation.
authors.affiliation: Laboratory of Immune Regulation, Department of Microbiology and Immunology, Graduate School of Medicine, WPI Immunology Frontier Research Center, Osaka University.
authors.forename: Ryu
authors.initials: R
authors.lastname: Okumura
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Takeda
mesh_terms: D000818:Animals; D004847:Epithelial Cells / Q000166:cytology; D041981:Gastrointestinal Tract / Q000276:immunology* / Q000382:microbiology; D006706:Homeostasis / Q000276:immunology*; D006801:Humans; D007107:Immune System; D007113:Immunity, Innate; D064307:Microbiota