Differential down-regulation of COX-2 and MMP-13 in human skin fibroblasts by glucosamine-hydrochloride

BackgroundEvidence suggests anti-inflammatory effects of glucosamine (GS) on inflammatory diseases. COX-2 is an enzyme to produce prostaglandins. MMPs are the family of matrix metalloproteinases degradable of ECM. Excess expression of COX-2 or MMPs involves in skin inflammation.ObjectiveWe evaluated whether GS–HCl modulates expression of COX-2 and/or MMPs by IL-1β or PMA in human skin fibroblasts (HSF) or keratinocytes (HaCaT).MethodsHSF or HaCaT cells were exposed to IL-1β or PMA without or with GS–HCl. COX-2 or MMPs protein and mRNA expression, respectively, were analyzed by Western blot and RT-PCR. MTS assay was utilized to assess the cytotoxicity of GS–HCl on HSF cells.ResultsIn HSF cells, IL-1β treatment induced COX-2 and MMP-13 expressions in association with activation of ERKs, p38 MAPK, JNKs, and NF-κB. PMA treatment also induced COX-2 and MMP-13 expressions in association with p38 MAPK activation. Of interest, treatment with GS–HCl (10 mM) led to blockage of p38 MAPK activation, accumulation of 66 kDa COX-2 protein variant (without affecting COX-2 mRNA expression), and transcriptional down-regulation of MMP-13 in the IL-1β- or PMA-treated HSF cells. Distinctly, pharmacological inhibition of p38 MAPK with SB203580 was associated with transcriptional down-regulation of COX-2 and MMP-13 in the IL-1β- or PMA-treated HSF cells. In addition, the GS–HCl-mediated COX-2 protein modification was observed in both endogenous and PMA-induced COX-2 in HaCaT cells.ConclusionsGS–HCl differentially down-regulates COX-2 and MMP-13 expression in the IL-1β- or PMA-treated human skin fibroblasts via the p38 MAPK-independent COX-2 translational inhibition and the p38 MAPK-dependent MMP-13 transcriptional suppression, respectively.