Battle and balance at mucosal surfaces--the story of Shigella and antimicrobial peptides.

Shigella is a major cause of morbidity and mortality for children in many developing countries. Emergence of antibiotic-resistance among Shigella demands the development of effective medicines. Antimicrobial peptides (AMPs) are expressed in phagocytes and at epithelial surfaces and are important effector molecules of innate immunity. We have found that pathogens are able to turn off the endogenous expression of AMPs, resulting in serious infections such as shigellosis. A therapeutic rationale to prevent microbial invasion would be to strengthen the epithelial line of defence through enhancing AMP expression. We have identified several inducers of AMP-production, including butyrate, phenylbutyrate and vitamin D, which have been investigated in animal models of shigellosis as well as in clinical trials. We believe that the conceptual framework presented here can be applied to additional clinical entities and that this novel approach can be an alternative or complement to traditional antibiotics in the future.