Food-induced immune responses as origin of bowel disease?

Food-induced immune responses cause or influence a number of intestinal diseases. Food antigens may either directly affect the mucosal immune system, or food modulate the intestinal flora, which may alter the immune response. The system preventing food-induced immune responses is complex: The mucosal barrier is the primary mechanism of host defense. Secondly, the innate immune system can neutralize some of the pathogens or food antigens. Thirdly, the adaptive immune system normally is in a state of unresponsiveness called oral tolerance. Only if these mechanisms fail, can immune reactions be observed. There are diseases where food is the primary factor in the pathogenesis, such as food allergy and gluten-sensitive enteropathy. Both diseases are mediated by different types of immune reactions. Furthermore, allergic reactions may play a role in eosinophilic esophagitis and eosinophilic gastroenteritis. In chronic inflammatory bowel disease food influences the disease by the modulation of various factors such as intestinal bacterial flora or the inflammatory cascade. Yeast antigens, especially in people with a defect in the innate immune system, such as MBL-deficiency may lead to an enhanced immune reactivity to mannan antigens of yeast. This may have some significance in the perpetuation of intestinal inflammatory processes in patients with Crohn's disease.