Antimicrobial peptides

Abstract

The skin is traditionally viewed as a physical barrier to environmental insults. Its role in immunity goes beyond its role as simply a barrier, as it plays a dynamic role in regulating immune responses and controlling microbial populations, notably through the use of antimicrobial peptides (AMPs). In 1987, Zasloff and colleagues were one of the first to describe the existence of potent AMPs on the skin of vertebrates. Since then, numerous AMPs have been identified and characterized in human skin. AMPs are a heterogeneous group of small proteins with a wide spectrum of antimicrobial activity against bacteria, fungi, and viruses. These peptides are almost all positively charged and amphipathic, allowing for the peptides to be soluble in an aqueous environment while still retaining an ability to bind bacterial membranes and walls. Once bound to the target membrane, the peptides kill through various mechanisms that involve both the physical perforation of pathogens and triggering of the host immune response. This chapter will focus on known AMPs present in human skin, with special focus given to defensins, cathelicidins, granulysins, S100 proteins, and ribonucleases; and their involvements in the etiology of dermatologic diseases.