Etiopathogenesis of chronic inflammatory bowel diseases. Role of the immune system

The challenge of the mucosal immune system is to develop tolerance toward intestinal antigens. Considering the quantity of bacteria that continuously attack the intestinal barrier, one can only imagine the complexity involved. To master this task, a tight network between the intestinal microbiota, the barrier, immune cells of the lamina propria as well as the adjacent mesenteric fat tissue is required. The key pathways involved have been revealed by the genome-wide association studies as well as functional data from experimental models. However, although knowledge with regard to the pathogenesis of chronic inflammatory bowel disease has been increasing continuously over recent decades, the current therapeutic strategies are limited to controlling the pro-inflammatory effector phase rather than achieving cure. The best example is cytokine neutralizing antibodies. The present review aims to describe the role of the various cell populations within the intestinal wall for disease pathogenesis and, thus, identify possible therapeutic strategies.