Immunological homeostasis for understanding inflammatory bowel diseases

Inflammatory bowel diseases are thought to be caused by a complex interaction of genetic, immunological, and environmental factors. The involvement of immunological factors in the etiology of inflammatory bowel diseases is suggested by various facts, such as 1) the effectiveness of immunosuppressive agents, steroids, and anti-TNF-α antibody; 2) the presence of autoantibodies, and 3) the spontaneous development of chronic colitis in mice lacking a single immunity-related gene, e.g., IL-2 or TGF-β. In particular, the treatment of Crohn's disease using anti-TNF-α antibody has been applied to clinical practice with satisfactory clinical results all over the world. This article describes the immunological pathology of inflammatory bowel diseases as autoimmune diseases, and outlines prospective new treatment methods based on the nature of the disease.