Sphingosylphosphorylcholine-induced interleukin-6 production is mediated by protein kinase C and p42/44 extracellular signal-regulated kinase in human dermal fibroblasts

Background: Sphingosylphosphorylcholine (SPC) has been reported as a novel lipid mediator that exerts various actions on wound heating process. Objective: The aim of this study is to evaluate the involvement of interleukin-6 (IL-6) in SPC-induced wound heating acceleration. Methods: We performed immunohistochemical analysis to demonstrate the IL-6 induction by SPC. To analyze the signaling events, skin fibroblasts were treated with SPC, and then RT-PCR, ELISA and Western blot analyses were carried out. Results: SPC markedly induced interleukin-6 (IL-6) expression in rabbit ear wound. SPC also induced IL-6 expression at both the mRNA and protein levels in human dermal fibroblasts cultured in vitro. SPC rapidly phosphorylated p42/44 extracellular signal-regulated kinase (ERK). Pretreatment with PD 98059, a specific MAPK kinase 1/2 inhibitor, markedly suppressed SPC-induced IL-6 expression in a dose-dependent manner. Protein kinase C (PKC) activation by phorbol myristate acetate (PMA) potentiated IL-6 mRNA expression, whereas PKC inhibition by bisindolytmaleimide blocked SPC-induced p42/44 ERK phosphorylation and IL-6 expression. Over-expression of PKC alpha markedly induced the IL-6 expression and p42/44 ERK activation. Conclusion: These results suggest that SPC-induced IL-6 production is mediated by PKC-dependent p42/44 ERK activation in human dermal fibroblasts cultured in vitro. (C) 2007 Japanese Society for Investigative Dermatology. Published by Elsevier Ireland Ltd. All rights reserved.