Signal Transduction and Nuclear Responses in Staphylococcus aureus- Induced Expression of Human β-Defensin 3 in Skin Keratinocytes

Publisher Website
Google Scholar
Abstract
The human β-defensin 3 (hBD-3) is an inducible epithelial peptide antibiotic that has potent antistaphylococcal activity. Infection of skin epithelial cells with viable Staphylococcus aureus , a common skin pathogen, induces increased gene expression of hBD-3 and other antimicrobial peptides. The aim of this study was to identify signaling pathways and nuclear responses that contribute to the gene expression of hBD-3 in primary human keratinocytes upon contact with S. aureus . Increased hBD-3 peptide was observed by immunofluorescence microscopy in keratinocytes exposed to S. aureus and to lipoteichoic acid (LTA). Both are ligands for the cell surface Toll-like receptor 2 (TLR2), and thus the contribution of TLR2 signaling in hBD-3 expression was examined. Functional inhibition of TLR2 prior to S. aureus stimulation significantly decreased hBD-3 mRNA levels by 37%, attesting to the involvement of this surface receptor in the initial recognition and downstream signaling for hBD-3 expression. Treatment of keratinocytes with a p38 mitogen-activated protein kinase (MAPK) inhibitor prior to either S. aureus or LTA stimulation was associated with reduced hBD-3 mRNA transcripts and peptide. We also propose a role for the MAPK-regulated transcriptional activating protein 1 in S. aureus -induced hBD-3 gene expression. Combined, these studies indicate a role for TLR2 signaling and MAPK activation in the upregulation of hBD-3 and demonstrate the innate immune capacity of skin keratinocytes under conditions of S. aureus challenge to enhance the local expression of this antistaphylococcal peptide antibiotic.

This publication has 27 references indexed in Scilit: