The Expression and Regulation of Interleukin-33 in Human Epidermal Keratinocytes: A New Mediator of Atopic Dermatitis and Its Possible Signaling Pathway

Interleukin (IL)-33 is a novel member of the IL-1 superfamily of cytokines that has recently become a focal point for research into the pathogenesis of atopic dermatitis (AD). However, the expression and regulation of IL-33 in human epidermal keratinocytes have not well been delineated. The aim of this study was to evaluate IL-33 and its receptor ST2L expression in skin lesions of AD patients and explored the signal transduction mechanisms leading to the IL-33 expression and of the IL-33’s pharmacological action in keratinocytes from AD patients (ADKs) and those from healthy controls (NHEKs). We performed immunocytochemistry, reverse transcription-polymerase chain reaction, Western blotting, and enzyme-linked immunosorbent assay to investigate ADKs compared with NHEKs. We found that IL-33/ST2L were positively expressed in the skin lesions of AD patients and a high expression of IL-33 was induced in keratinocytes by IL-4 plus interferon [IFN]-γ or IFN-γ alone at the mRNA and protein levels. Meanwhile, IFN-...