Prostaglandin D2 induces the production of human β-defensin-3 in human keratinocytes

The antimicrobial peptide human beta-defensin-3 (hBD-3) is produced by epidermal keratinocytes and protects the skin from infections. This peptide induces the release of a lipid mediator, prostaglandin D-2 from dermal mast cells. Prostaglandin D-2 binds to cell-surface G protein-coupled receptors, D prostanoid receptor, and chemoattractant receptor-homologous molecule expressed on T helper cell type 2 (CRTH2). Both receptors are detected on epidermal keratinocytes. It is reported that prostaglandin D-2 is involved in cutaneous allergy, however, its role in antimicrobial defense is unknown. We examined the in vitro effects of prostaglandin D-2 on hBD-3 production in normal human keratinocytes. Prostaglandin D-2 enhanced hBD-3 secretion and mRNA expression in human keratinocytes. Prostaglandin D-2-induced hBD-3 production was suppressed by the CRTH2 antagonist ramatroban and by antisense oligonucleotides against c-Jun and c-Fos, components of a transcription factor, activator protein-1 (AP-1). Prostaglandin D-2 enhanced the transcriptional activity and DNA binding of AP-1, expression, phosphorylation, and DNA binding of c-Fos proteins in keratinocytes. Prostaglandin D-2-induced hBD-3 production, AP-1 activity, and c-Fos expression and phosphorylation were suppressed by 00126, PP2, and pertussis toxin, which are inhibitors of mitogen-activated protein kinase kinase (MEK), src, and G; proteins, respectively. The phosphorylation of extracellular signal-regulated kinase (ERK), downstream kinase of MEK, was induced by prostaglandin D-2, and suppressed by ramatroban, pertussis toxin, PP2, and U0126. These results suggest that prostaglandin D-2 induces hBD-3 production in human keratinocytes by activating AP-1 through the expression and phosphorylation of c-Fos via the CRTH2/G(i)/src/MEK/ERK pathway. Prostaglandin D-2 may promote cutaneous antimicrobial activity via hBD-3. (C) 2009 Elsevier Inc. All rights reserved.