Paneth cells and the innate immune response.

PURPOSE OF REVIEW: To review recently published studies presenting novel and relevant information on Paneth cells and their function. RECENT FINDINGS: Paneth cells are secretory epithelial cells which are predominantly found in the small-intestinal crypts of Lieberkühn. Their most abundant products are alpha-defensins, which are endogenous antibiotics with activity against gram-negative and gram-positive bacteria, fungi, viruses and protozoa. The differentiation from stem-cell progenitors to Paneth cells is regulated by Wnt signalling via a complex gene programme, terminally including defensins. A disturbance of Paneth-cell differentiation and function may predispose to intestinal infections and appears to be a critical factor in the pathogenesis of ileal Crohn's disease, an inflammatory disease of the intestinal tract. SUMMARY: It is conceivable that these recent findings together with a better understanding of underlying mechanisms involved in the regulation and biology of Paneth cells will open up new therapeutic avenues for preventing infection as well as for causally treating inflammatory bowel diseases.