Antimicrobial peptides in human skin.

Human skin is permanently exposed to a wide variety of potential harmful microorganisms. Despite these microbial threats, skin is surprisingly highly resistant against infections. Various studies in the last decade discovered a chemical cutaneous defense system based on the production of antimicrobial proteins. These antimicrobial proteins act as a first defense line through their broad spectrum of potent antimicrobial activity. In addition to constitutively expressed antimicrobial proteins, production of various antimicrobial proteins in keratinocytes is induced by bacterial compounds as well as proinflammatory cytokines. The resulting local accumulation of antimicrobial proteins offers a fast and very efficient way to prevent microbes from establishing an infection. In this review we summarize the current status of our knowledge of expression of antimicrobial proteins in human skin.