Pathogenesis of inflammatory bowel disease.

The causes of IBD (inflammatory bowel disease), ulcerative colitis and Crohn's disease, have not been elucidated. It is thought that the pathogenesis involves genetic predisposition, environmental factors and host immune response to food antigens and microbiota. Most of IBD susceptiblity genes are related to function of immune cells, maintenance of homeostasis of epithelial cells, autophagy, ER stress and so on. These genetic abnormalities may induce abnormal immune response to antigens and intestinal bacteria, which are modified by diet habit and hygiene environment. Recently, the interrelationship between intestinal bacteria and hosts has dramatically been elucidated, and breakdown of the homeostatic mechanisms at the cellular level is revealed to have an important role in the onset of IBD.