[Pathogenesis of chronic inflammatory bowel diseases]

Genetic predisposition, nutritional and environmental influences, intestinal pathogens, psychological stress, and disturbed intestinal barrier function have been accepted as important factors in the pathogenesis of chronic inflammatory bowel diseases. Uncontrolled reactions of T-cells and proinflammatoric cytokines are the common denominator of all factors contributing to pathogenesis. The detection of NOD2 gene mutation in about 25% of patients with Crohn's disease was an important step towards an understanding of the molecular background of the disease. The NOD2 proteins functions as an intracellular sensor of bacterial cell membrane constituents and is a crucial part of the innate immune system. In Crohn's disease, the secretion of defensins, naturally occurring antimicrobial peptides, is disturbed. There is evidence that several pathways involved in the reaction of the innate immune system may be disturbed in CED, ultimately leading to an uncontrolled activity of the adaptive immune system.