Effects of lectin-like oxidized low density lipoprotein on MMP-9 in human monocyte-macrophage-derived foam cells

Objective To investigate how ox-LDL affects expression and activity of MMP-9 secreted by human monocyte-macrophage-derived foam cells and role of LOX-1 in this procedure. Methods The second to sixth passages of human monocyte-derived macrophages cultured in vitro were used in this experiment. The macrophages were allocated to several groups depending on incubation with 20, 40 or 80 mg/ L ox-LDL for 24 hours, or 40 mg/ L ox-LDL for 1, 12 or 24h. In addition, an intervention group was set where macrophages were incubated with polyinosinic acid (Poly I), a LOX-1 blocker. The expressions of MMP-9 mRNA and Lox-1 mRNA were determined with RT-PCR, and the activity of MMP-9 by zymography. Results Expressions of LOX-1 and MMP-9 mRNA and secretion and activity of MMP-9 were increased by ox-LDL in a concentration-and time-dependent manner (P0.05); Inhibition with polyinosinic acid was clearly associated with a decline in, expressions and activity of MMP-9 mRNA (P0.05). Conclusion LOX-1 as a specific receptor of ox-LDL may be responsible for ox-LDL mediated up-regulation of LOX-1 and MMP-9 expressions and activity in monocyte/macrophages.