HMG-CoA reductase inhibition reduces monocyte CC chemokine receptor 2 expression and monocyte chemoattractant protein-1-mediated monocyte recruitment in vivo

Background - The migration of circulating monocytes to the arterial wall during atherogenesis is largely modulated by activation of the CC chemokine receptor 2 (CCR2), a dominant monocyte chemotaxis receptor. The present study investigated whether 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibition affects CCR2 gene expression and CCR2-dependent monocyte recruitment. Methods and Results - Competitive reverse transcription-polymerase chain reaction analysis and flow cytometry showed that simvastatin, an HMG-CoA reductase inhibitor, dose-dependently reduced monocyte CCR2 mRNA and protein expression. Treatment of 21 normocholesterolemic men with simvastatin (20 mg/d for 2 weeks) decreased CCR2 protein and mRNA expression in circulating monocytes. Promoter and electrophoretic mobility shift assays showed that simvastatin activated a peroxisome proliferator response element in THP-1 monocytes. Moreover, simvastatin-induced CCR2 downregulation was completely reversed by the synthetic peroxisome proliferator-activated receptor-γ antagonist GW9662. Simvastatin-treated monocytes showed little chemotaxis movement in response to monocyte chemoattractant protein-1 (MCP-1), a specific CCR2 ligand. Treatment of C57/BL6 mice with simvastatin (0.2 μg/g body weight IP, daily for 1 week) inhibited transmigration of CD80⁺ monocytes to the MCP-1-injected intraperitoneal space. Moreover, few circulating inflammatory cells from simvastatin-treated Sprague-Dawley rats (0.2 μg/g body weight IP, daily for 2 weeks) were recruited to the aortic wall of hypercholesterolemic littermates. Conclusions - The inhibition of CCR2/MCP-1-dependent monocyte recruitment by simvastatin may prevent excessive accumulation of monocytes in the arterial wall during atherogenesis.