Background: The effect of a calcium channel blocker (CCB) on the expression of monocyte chemoattractant protein (MCP)-1 was explored in inflammatory vascular injury, focusing on the role of nuclear factor (NF)-kappaB.
Methods: Vascular injury was induced by cuff placement. Expression of MCP-1 was determined by real-time RT-PCR. NF-kappaB expression and its activity were detected by Western blot and electrophoretic mobility shift assay.
Results: Polyethylene cuff placement around the mouse femoral artery increased MCP-1 expression, together with proliferation of vascular smooth muscle cells and neointimal formation in the injured artery. The content of NF-kappaB was decreased in the cytosolic fraction but increased in the nuclear fraction prepared from the injured artery. In the nuclear fraction, the binding activity of NF-kappaB to the promoter region of MCP-1 was markedly increased. On the other hand, IkappaB content in the cytosolic fraction was decreased in the injured artery after cuff placement, accompanied by an increase in IkappaB kinase (IKK) phosphorylation. Treatment of mice with a CCB, nifedipine, at a dose of 5 mg/kg/day, significantly decreased vascular smooth muscle cell proliferation and neointimal formation without affecting blood pressure. This dose of nifedipine inhibited the increase in MCP-1 expression in the injured artery. Moreover, nifedipine reduced the nuclear content and DNA-binding activity of NF-kappaB in the injured artery. In contrast, the decrease in IkappaB content and the increase in IKK phosphorylation in the cytosolic fraction were attenuated by nifedipine.
Conclusions: These results indicate that MCP-1 expression in inflammatory vascular injury is regulated by activation of NF-kappaB. The results also suggest that nifedipine attenuates MCP-1 expression in the injured artery via inhibition of the nuclear translocation and DNA-binding activity of NF-kappaB, and thereby improves vascular remodeling.