Preface: The Epidermal Skin Barrier: Aspects of Biology and Dysfunction

Preface: The Epidermal Skin Barrier: Aspects of Biology and Dysfunction Epithelial barrier function has emerged as a critical driving force in the development and progression of allergic diseases. Invading pathogens and environmental allergens engage the epithelial barrier as an initial line of defense imparted by the host. This response is important in shaping the adaptive immune response that ensues. Recent publications documenting a role for the epidermal skin barrier in driving inflammation in atopic dermatitis have risen to the forefront of research in allergic diseases, because it is likely that a similar principle is found in localization of allergic respiratory responses in asthma or allergic rhinitis and the gut mucosa in food allergy. During the past year, the Journal has published several outstanding reviews and original articles that address various aspects of the epithelial immune response and the role of barrier function in the pathobiology of atopic dermatitis. In the current supplement, Alan Irvine and his colleagues present a compelling body of data that supports an important role for loss-of-function mutations in

the skin structural protein filaggrin as a major risk factor for atopic dermatitis and the atopic march. Importantly, the article by Howell et al demonstrates that TH2 responses can downregulate filaggrin, suggesting a more global mechanism by which allergen sensitization could contribute to skin inflammation in atopic dermatitis. Schauber and Gallo examine the mechanisms by which antimicrobial peptides protect the skin from infection and raise the interesting possibility that oral vitamin D supplementation may augment the skin innate immune response. Finally, Jensen et al report on the effects of anti-inflammatory therapies on the skin barrier in atopic dermatitis. We are pleased to present this collection of articles from the Journal in a single supplement that highlights the lab bench to bedside implications of research in this area. Donald Y. M. Leung, MD, PhD Denver, Colo

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