Abstract
Defects in the intestinal barrier play a central role in disease pathogenesis. Recently we have demonstrated that children with ileal Crohn's disease show a reduced expression of small intestinal HD-5 at the age of onset suggesting that a compromised mucosal barrier function might be a key factor in the early disease pathogenesis. We also identified a disturbance of the Wnt signaling transcription factor TCF-4 as a major mechanism for this deficiency in children which might result in a compromised innate immune function of small intestinal Paneth cells via defensin secretion. Here we provide a summary on our recent findings and discuss the data in more detail especially focusing on the role of Paneth cell differentiation and function in the pathogenesis of pediatric ileal Crohn's disease.