The oral anti-diabetic agent, gliclazide, inhibits oxidized LDL-mediated LOX-1 expression, metalloproteinase-9 secretion and apoptosis in human aortic endothelial cells

The mechanisms linking diabetes to plaque rupture and thrombotic occlusion remain largely speculative, yet matrix metalloproteinases (MMP) and endothelial apoptosis may represent central elements. Binding of oxidized low-density lipoprotein (oxLDL) to endothelial lectin-like oxidized LDL receptor-1 (LOX-1) induces oxidative stress, MMP expression and apoptosis. In the present study, we examined the effect of gliclazide, a second generation sulfonylurea with antioxidant properties, on LOX-1 expression and LOX-1-mediated MMP-9 expression and apoptosis in oxLDL-treated human aortic endothelial cells (HAECs). Incubation of HAECs with oxLDL increased LOX-1 expression and enhanced MMP-9 production by these cells. Treatment with an anti-LOX-1 antibody or with antioxidants, including gliclazide, inhibited these effects. Induction of LOX-1 and LOX-1-mediated MMP-9 production involved endothelin-1 production and nuclear factor-kappaB activation. These biological parameters were inhibited by gliclazide and anti-LOX-1 antibody treatment. In HAECs, oxLDL induced apoptosis, an effect associated with reduced protein kinase B (PKB) activity. Anti-LOX-1 antibody, antioxidants including gliclazide, as well as caspase inhibitors prevented oxLDL-induced apoptosis. The anti-apoptotic effect of gliclazide was associated with an increase in PKB activity and a decrease in caspase-3 and -9 activities. These results demonstrate that gliclazide inhibits endothelial LOX-1 expression and prevents LOX-1-mediated proatherogenic effects associated with endothelial dysfunction and plaque rupture.