Abstract:

Objective To investigate the effects and mechanism of visfatin on matrix metalloproteinases-9 (MMP-9) expression and invasive activity in macrophages. Methods THP-1 monocytes were induced into macrophages. To investigate the effects of visfatin on MMP-9, cells were divided into 2 groups: ①macrophages+visfatin 12 h；②macrophages+visfatin 24 h. The concentrations of visfatin in each group were：0（control）, 50, 100, 200, 400 ng/mL. MMP-9 mRNA and protein expression were analysed by RT-PCR and Western blotting, and MMP-9 invasive activity was assayed by gelatin zymography. To investigate the mechanism of visfatin on MMP-9, cells were divided into 5 groups: ①macrophages without stimulation (control); ②macrophages pretreated with MAPK p38, ERK1/2, JNK pathway inhibitor for 1 h, then stimulated with visfatin （200 ng/mL）for 24 h; ③macrophages pretreated with retinoid X receptors (RXR) nature ligand or peroxisome proliferators activated receptor γ （PPARγ） natural/synthetic ligand for 1 h，then stimulated with visfatin（200 ng/mL）for 24 h; ④macrophages stimulated with visfatin (200 ng/mL) for 24 h; ⑤macophages+visfatin （200 ng/mL）for different time（5, 10, 15, 30, 60 min）. MMP-9 expression, PPARγ expression, and the effect of visfatin on MAPK phosphorylation were analysed by Western blotting. Results Visfatin not only significantly enhanced MMP-9 mRNA and protein expression in macrophages（P<0.05, P<0.01）, but also up-regulated MMP-9 invasive activity（P<0.01）. p38 MAPK inhibitor, ERK1/2 MAPK inhibitor and RXR ligand significantly blocked visfatin activity. Visfatin activated the phosphorylation of p38 MAPK and ERK1/2 MAPK, while had no effect on expression of PPARγ protein. Conclusion Visfatin enhances inflammatory factors expression and activity in macrophages which is related with ERK1/2 MAPK and p38 MAPK, and RXR may mediate visfatin activity.

Key words: visfatin, matrix metalloproteinase, mitogen-activated protein kinase, retinoid X receptors, atherosclerosis