Endogenous Antimicrobial Peptides and Skin Infections in Atopic Dermatitis

Staphylococcal infections of the skin are more common in patients with atopic dermatitis than they are in normal persons or patients with psoriasis. In this study, the investigators hypothesized that the elevated rate of skin infections in atopic dermatitis could be attributed to reduced levels of the endogenous antimicrobial peptides LL-37 and human β-defensin 2. They found that the levels of these peptides were lower in skin from patients with atopic dermatitis. The skin's first line of defense against invasion by microbial agents is the stratum corneum, a nonviable, desiccated layer of the epidermis. 1 However, this physical barrier is susceptible to injuries that allow the entry of opportunistic microbial agents into the skin. The innate immune system can immediately respond to this intrusion by helping to prevent further invasion. This immune response includes phagocytosis by neutrophils and macrophages and their production of reactive oxygen intermediates that kill microbial agents. 2 A number of endogenous antimicrobial peptides have been shown to play an integral part in innate immunity. 3 Two major classes of peptides in . . .