Visfatin/PBEF/Nampt induces EMMPRIN and MMP-9 production in macrophages via the NAMPT-MAPK (p38, ERK1/2)-NF-κB signaling pathway

Abstract

The adipocytokine visfatin is closely associated with metabolic disorders. This study explored the effects of visfatin on macrophage-induced inflammation in atheroma. The ability of visfatin to enhance extracellular matrix metalloproteinase inducer (EMMPRIN) expression, matrix metalloproteinase-9 (MMP-9) production and enzymatic activity in THP-1 derived macrophages as well as the mechanisms involved were investigated. EMMPRIN and MMP-9 mRNA levels were investigated by RT-PCR. EMMPRIN and MMP-9 protein levels, nuclear factor (NF)-κB -p65 protein levels, peroxisome proliferator-activated receptor γ (PPARγ) protein levels, and mitogen-activated protein kinase (MAPK) phosphorylation were determined by Western blotting. MMP-9 enzymatic activity was assayed by gelatin zymography. Visfatin (50-400 ng/ml) induced EMMPRIN and MMP-9 depending on the dosage used. Visfatin elicited the activation of NF-κB and MAPK (p38, ERK1/2). Exogenous nicotin-amide mononucleotide (NMN), the product of nicotinamide phosphoribosyltransferase (NAMPT) activity, mimicked the effects of visfatin on MAPK (p38, ERK1/2)-NF-κB activation and EMMPRIN/MMP-9 induction. Using the p38 inhibitor, SB203580, the ERK1/2 inhibitor PD98059, the NF-κB inhibitor, pyrrolidine dithiocarbamate and the NAMPT inhibitor FK866, we demonstrated that the visfatin pro-inflammatory action was through the NAMPT-MAPK (p38, ERK1/2)-NF-κB pathway. Furthermore, the visfatin pro-inflammatory action was not prevented by insulin receptor blockade or by a PPARγ agonist. Visfatin did not modulate PPARγ expression. Retinoid X receptor (RXR) agonist suppressed the effects of visfatin on EMMPRIN/MMP-9, NF-κB, but not on MAPK activation. In conclusion, we have demonstrated that visfatin enhances atheroma inflammation through the NAMPT-MAPK (p38, ERK1/2)-NF-κB-EMMPRIN/MMP-9 pathway, a key feature of atherosclerotic diseases linked to metabolic disorders.