FSL-1 Induces MMP-9 Production through TLR-2 and NF-κB/AP-1 Signaling Pathways in Monocytic THP-1 Cells

Background: Matrix metalloproteinase-9 (MMP-9) is known to be implicated in the pathogenesis of many inflammatory disorders. FSL-1 (fibroblast-stimulating lipopeptide-1) induces cytokine production by monocytes/macrophages. However, it is unclear whether FSL-1 is also able to induce MMP-9 production. Herein, we determined whether FSL-1 could induce MMP-9 production, and if so, which signal transduction pathway(s) were involved. Methods: MMP-9 expression was assessed with real-time qPCR and ELISA. Signaling pathways were studied by using THP1-XBluer (TM) cells, THP1-XBlue (TM)-defMyD cells, anti-TLR2 mAb and pharmacological inhibitors. Phospho and total proteins were determined by Western blotting. Results: FSL-1 induces MMP-9 expression (P<0.001) at both mRNA and protein levels in human monocytic THP-1 cells. Elevated activity (P<0.001) of NF-kappa B/AP-1 was also observed in FSL-1-treated THP-1 cells. FSL-1-induced MMP-9 secretion was markedly suppressed either by neutralizing anti-TLR-2 antibody or by inhibiting clathrin-dependent endocytosis. Furthermore, MyD88(-/-) THP-1 cells did not express MMP-9 in response to FSL-1 treatment. By small interfering RNA-mediated knockdown, we also show that FSL-1-induced up-regulation of MMP-9 requires MyD88. Pre-treatment of THP-1 cells with inhibitors of JNK (SP600125), MEK/ERK (U0126; PD98056; XMD 8-92), p38 MARK (SB203580) and NF-kappa B (BAY11-7085, Triptolide, Resveratrol) significantly suppressed (P<0.05) MMP-9 gene expression and NF-kappa B/AP-1 transcription factors activity. Conclusion: These findings provide the first evidence that FSL-1 induces TLR-2-dependent MMP-9 gene expression which requires the recruitment of MyD88 and leads to activation of MEK1/2/ERK 1/2, MEK5/ERK5, JNK, p38 MARK and NF-kappa B/AP-1. Copyright (C) 2014 S. Karger AG, Basel.