Expression of antimicrobial peptides in atopic dermatitis and possible immunoregulatory functionsKopfnagel, Verena; Harder, Jürgen; Werfel, ThomasCurrent Opinion in Allergy & Clinical Immunology: October 2013 - Volume 13 - Issue 5 - p 531–536 doi: 10.1097/ACI.0b013e328364ddfd SKIN ALLERGY: Edited by Torsten Zuberbier and Thomas Werfel Abstract Author Information Purpose of review: To summarize the findings on the expression of antimicrobial peptides in the skin in inflammatory skin diseases and particularly in atopic dermatitis. Moreover, the literature addressing the functions of antimicrobial peptides (AMPs) beyond antimicrobial activities with impact on allergic skin inflammation is summarized as well. Recent findings: Although lower expressed than in psoriasis, most AMPs have been shown to be either constitutively expressed or upregulated in atopic dermatitis as well. A number of immunoregulatory functions which might impact on allergic skin inflammation have been described for several antimicrobial peptides, mainly for human β-defensins and the cathelicidin LL-37. Summary: From the recent literature, there is considerable evidence that AMPs are induced in the skin in atopic dermatitis. However, some studies suggest that the induction, release or mobilization of some AMPs in atopic dermatitis may not reach sufficient levels to provide adequate control of cutaneous microbial colonization. Th2 cytokines appear to negatively influence the expression and induction of some AMPs. A number of immunoregulatory functions have been described for several AMPs. Most of them point to a proinflammatory function of AMPs in addition to their antimicrobial activities. Further studies are needed to clarify the role of AMPs in atopic dermatitis. aDivision of Immunodermatology and Allergy Research, Department of Dermatology and Allergy, Hannover Medical School, Hanover bDepartment of Dermatology, University Hospital Schleswig-Holstein, Kiel, Germany *These authors contributed equally to this article. Correspondence to Verena Kopfnagel, Division of Immunodermatology and Allergy Research, Department of Dermatology and Allergy, Hannover Medical School, Hanover, Germany. Tel: +49 511 532 5054; e-mail: Kopfnagel.Verena@mh-hannover.de Copyright © 2013 Wolters Kluwer Health, Inc. All rights reserved.