Molecular pathogenesis of inflammatory bowel disease: relevance for novel therapies

The immense load of microorganisms within the gastrointestinal tract is a great challenge for the mucosal immune system. Whereas the vast majority of commensal bacteria should be tolerated, pathogenic organisms have to be attacked. During inflammatory bowel disease, the balanced interaction between the mucosal flora and the intestinal immune system is disturbed. Various defective components of this complex interaction have been described, such as different susceptibility genes, impaired innate immune responses and environmental factors, suggesting that inflammatory bowel diseases are multifactorial diseases. Based on new insights into the pathogenesis of inflammatory bowel disease, various targets for future drugs have been identified and new substances are emerging. The following article will review the current understanding of inflammatory bowel disease pathogenesis in context with genetic risk factors, imbalanced innate and acquired immune responses, and altered barrier function. Clinical treatment of the diseases will be summarized and emerging therapies as well as individual management based on recent insights into pathogenesis will be discussed.