ag-490 and Dermatitis--Atopic

Atopic dermatitis (AD), a chronic, pruritic, inflammatory skin disease, is histopathologically characterized by epidermal hyperplasia and infiltration of T cells, mast cells, and eosinophils. Clinical study and basic research have established that IL-4 plays an important role in the pathogenesis of AD. In this report, using HaCat cells, we show that CCL26, a chemokine for eosinophils, is up-regulated by IL-4 at both the mRNA and protein levels. IL-4 also enhances CCL26 promoter activity. Serial 5' deletion of the promoter and mutagenesis study reveal that the proximal Stat site is the key response element for IL-4 regulation of CCL26. Although IL-4 increases phosphorylation of both Stat3 and Stat6, it only activates Stat6 as shown by dominant negative studies. In addition, we found that IL-4 induces Stat6 nuclear translocation and stimulates phosphorylation of Jak1 and Jak2 but not Tyk2. IL-4 up-regulation of CCL26 can be suppressed by Jak inhibitors in a dose-dependent manner. Taken together, results of this investigation reveal that IL-4 signals through the Jak1, 2/Stat6 pathway in keratinocytes to stimulate CCL26 expression and this may provide an explanation for the pathogenesis of AD.

Topics: Active Transport, Cell Nucleus; Blotting, Western; Cell Line; Cell Nucleus; Chemokine CCL26; Chemokines, CC; Dermatitis, Atopic; Dose-Response Relationship, Drug; Enzyme Inhibitors; Gene Expression; Humans; Immunohistochemistry; Interleukin-4; Janus Kinase 1; Janus Kinase 2; Keratinocytes; Luciferases; Phosphorylation; Promoter Regions, Genetic; Response Elements; Reverse Transcriptase Polymerase Chain Reaction; Signal Transduction; STAT6 Transcription Factor; Tyrphostins; Up-Regulation