Crohn’s disease-Defect in innate defence

Figure 1 Proposed model for the pathogenesis of ileal and colonic Crohn's disease. In the healthy ileal and colonic mucosa, luminal microbes are sufficiently eliminated by an adequate secretion of antimicrobials peptides (A). In ileal Crohn's disease, a reduction of the Wnt transcription factor TCF4 leads to a decreased alpha-defensin secretion. In colonic Crohn´s disease a reduced HBD2 copy number causes a weakened antimicrobial barrier mediated by the beta-defensins. Both changes may allow the luminal microbes to attach and invade in the mucosa triggering the inflammation (B).