Role of monocyte chemoattractant protein-1 in cardiovascular remodeling induced by chronic blockade of nitric oxide synthesis

Background-Chronic inhibition of endothelial nitric oxide (NO) synthesis by the administration of N-omega-nitro-L-arginine methyl ester (L-NAME) to ra ts induces early vascular inflammatory changes (monocyte infiltration into coronary vessels and monocyte chemoattractant protein-1 [MCP-1] expression) as well as subsequent arteriosclerosis (medial thickening and perivascular fibrosis) and cardiac fibrosis. However, the role of MCP-1 in this process is not known. Methods and Results-We investigated the effect of a specific monoclonal ant i-MCP-1 neutralizing antibody in rats treated with L-NAME to determine the role of monocytes in the regulation of cardiovascular remodeling. We found increased expression of MCP-1 mRNA in vascular endothelial cells and monocy tes in inflammatory lesions, Cotreatment with an anti-MCP-1 antibody, but n ot with control IgG, prevented the L-NAME-induced early inflammation and re duced late coronary vascular medial thickening. In contrast, the anti-MCP-1 antibody did not decrease the development of perivascular fibrosis, the ex pression of transforming growth factor (TGF)-beta (1) mRNA, or systolic pre ssure overload induced by L-NAME administration. Conclusions-These results suggest that MCP-1 is necessary for the developme nt of medial thickening as well as monocyte recruitment, In contrast, the p athogenesis of fibrosis may involve other factors, such as TGF-beta (1).