[Molecular biology background of inflammatory bowel disease]

The exact pathological background of inflammatory bowel disease has not been clarified yet. Many aspects of genetical and environmental factors, as well as certain alterations of the functions of epithelial cells and immunoregulation which may attenuate chronic inflammation in the gastrointestinal tract are known. These three components have many connecting points. Among the inflammatory bowel disease genes we know only the function of the NOD2/CARD gene, and we have some idea about the OCTN and DRG genes. The function of the intestinal epithelial cells is changed in inflammatory bowel disease. The latter two genes may have a role in the increased permeability, so as the tumor necrosis factor alpha, interferon gamma may play affect it. The interleukin-10 helps the mucosal integrity. The interleukin-6 production is elevated in these diseases, and the interleukin-8 level can be elevated in case of mutation of toll like receptor 5. The tumor necrosis factor alpha, interferon gamma and lymphotoxin-3-alpha increased the chemokine secretion and adhesion molecule expression also. The amount of certain cytokines are changed in inflammatory bowel disease. There were no association between the incidence and phenotype of Crohn's disease and cytokine gene polymorphisms, except the interleukin 6 gene. It seems that these alterations are secondary, and don't play a major role in the pathogenesis of inflammatory bowel disease.