Description
The β-defensins (beta-defensins) are an integral part of the congenital immune system and contribute with their antimicrobial effect to the barrier function of intestinal epithelial cells.
Defensins exert a variable degree of antimicrobial activity against bacteria, fungi, and some enveloped viruses. Vertebrate defensins are classified as alpha- or beta-defensins, based on their pattern of disulfide bridges. Nine human defensins of epithelial origin have been found, three of them being beta-defensins (HBD-1, -2 and -3). The expression of beta-defensins is induced by the pro-inflammatory cytokines and also through microorganisms (e.g. E. coli, H. pylori or P. aeruginosa). For example, A beta-defensin 2 deficiency can be observed in the intestinal mucous of patients with Crohn’s disease. The defense system of the mucous membrane is therefore restricted and allows an increased invasion of bacteria, which could possibly lead to a typical infection in Crohn’s disease patients. Whether the beta-defensin 2 deficiency could even play a role in the development of Crohn’s disease is currently being researched as well as the possibility that it is the probiotic bacterium, which produces beta-defensin. Reduced β-defensin levels are associated with Crohn’s disease (HBD-2) and increased β-defensin levels are associated with Colitis Ulcerosa (HBD-2).
