Antibacterial peptides and gastrointestinal diseases.

Defensins and cathelicidins are small cationic peptides produced by neutrophils and epithelial cells. They are highly expressed during infection. The role of constitutive and inducible antibacterial peptides has been extensively studied over the recent years; especially in the gastrointestinal (GI) tract, where the balance between the luminal bacteria and antibacterial peptides is crucial in the maintenance of a healthy GI tract. There are reports showing that the expressions of defensins and cathelicidins in the gut are dysregulated in various disease states. They could participate in the development of different disorders ranging from inflammation to cancer. Experimental findings showed that supplementation with animal cathelicidin promoted gastric ulcer healing in rats and suppressed tumorigenesis of gastric cancer in mice. Mouse cathelicidin could alleviate murine colitis by preserving mucus content and suppression of apoptosis. Other clinical applications for these antibacterial peptides are awaiting for further studies.