Inhibition of MCP-1/CCR2 signaling pathway is involved in synergistic inhibitory effects of irbesartan with rosuvastatin on vascular remodeling

Abstract

Additional beneficial effects of angiotensin II type 1 (AT₁) receptor blockers beyond AT₁ receptor blockade have been highlighted. Irbesartan is reported to act as an antagonist of the monocyte chemoattractant protein-1 (MCP-1) receptor, C-C chemokine receptor 2 (CCR2). We examined the possible synergistic effects of the combination of irbesartan with rosuvastatin on preventing vascular remodeling focusing on the MCP-1/CCR2 pathway. We observed that administration of irbesartan and CCR2 antagonist, propagermanium, at noneffective doses, decreased the neointima with a decrease in PCNA labeling index in the injured mouse femoral artery induced by cuff placement. We also observed that administration of a noneffective dose of rosuvastatin with propagermanium decreased the neointima area, suggesting that the inhibitory effect of rosuvastatin on neointima formation is at least partly attributable to blockade of the MCP-1/CCR2 pathway. Moreover, we demonstrated that the combination of irbesartan with rosuvastatin decreased neointima formation. MCP-1 mRNA level was significantly increased in injured femoral arteries, and administration of irbesartan with rosuvastatin decreased the mRNA levels of MCP-1, TNFα, and IL-1β, and increased PPARγ mRNA expression. These results suggest that the synergistic inhibitory effects of irbesartan with rosuvastatin on neointima formation may involve attenuation of MCP-1/CCR2 signaling.

Introduction

Vascular inflammation plays a crucial role in atherosclerosis, and its regulation is important to prevent cardiovascular disease.¹ Angiotensin II (Ang II) type 1 (AT₁) receptor-mediated actions exert vascular remodeling through both direct effects to increase blood pressure and indirectly via enhancement of vascular inflammation.² AT₁ receptor blockers (ARBs) have been widely used as antihypertensive drugs with the expectation of vascular protective effects. We have previously reported that blockade of the AT₁ receptor attenuated vascular remodeling induced by inflammatory vascular injury after polyethylene cuff placement, indicating involvement of AT₁ receptor stimulation in vascular remodeling.3, 4

Recently, additional beneficial effects of ARBs have been highlighted.5, 6 Some ARBs, such as telmisartan and irbesartan, have been reported to have a partial peroxisome proliferator-activated receptor (PPAR)-γ agonistic action.7, 8 In addition, irbesartan is reported to have higher affinity for C-C chemokine receptor 2 (CCR2), the monocyte chemoattractant protein-1 (MCP-1) receptor, than other ARBs, such as losartan, based on molecular modeling.⁹ It was also reported that irbesartan inhibited MCP-1 production more strongly than did losartan.¹⁰ This effect of irbesartan could be attributable to inhibitory effects on nuclear factor-kappa B (NF-κB) activation and was independent of AT₁ receptor blockade. Consistent with these results, we recently reported that irbesartan, together with propagermanium, an MCP-1 receptor antagonist, exerted beneficial effects on ischemic brain damage at least owing to its inhibitory effects on MCP-1/CCR2 signaling beyond AT₁ receptor blockade.¹¹

The MCP-1/CCR2 pathway is a major key player in vascular inflammation and remodeling. The roles of the MCP-1/CCR2 pathway in vascular remodeling have been well studied in many experimental animal models.¹² MCP-1 and CCR2 are upregulated in vascular wall cells and cooperate in recruitment of inflammatory cells, such as monocytes and leukocytes, to the injured artery.¹³ In different animal models of arterial injury, inhibition of the MCP-1/CCR2 pathway significantly reduced intimal hyperplasia.¹⁴ For instance, anti-MCP-1 gene therapy inhibited early vascular inflammation, including monocyte infiltration, increased expression of MCP-1, and inflammatory cytokines, resulting in late neointimal formation.¹⁵ These results suggest that inhibition of the MCP-1/CCR2 pathway is important in preventing vascular inflammation and consequent remodeling.

The anti-inflammatory and antiatherogenic effects of 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (statins) have been extensively studied.¹⁶ Statins have been shown to inhibit MCP-1 expression in the atherogenic arterial wall¹⁷ and MCP-1/CCR2-dependent monocyte recruitment.¹⁸ Yano et al.¹⁹ demonstrated that statins induced a cyclooxygenase (COX)-2-dependent increase in intracellular 15-deoxy-Δ-12, 14-prostaglandin J₂ (15d-PGJ₂) level through both a RhoA- and Cdc42-dependent p38 mitogen-activated protein kinase (MAPK) pathway and a RhoA- and Cdc42-independent extracellular signal regulated kinase (ERK) 1/2 pathway, thereby activating PPAR-γ. In a recent large clinical study, rosuvastatin significantly reduced the incidence of major cardiovascular events in healthy persons without hyperlipidemia but with higher high-sensitivity C-reactive protein levels, suggesting additional beneficial effect of rosuvastatin in addition to its lipid-lowering effect.²⁰ Another recent clinical study using intravascular ultrasonography also showed that maximal doses of rosuvastatin showed significant benefit in atherosclerotic disease regression assessed by total atheroma volume.²¹ These results led us to examine the possibility that irbesartan could exert beneficial effects on vascular remodeling via possible synergistic actions with rosuvastatin by inhibition of the MCP-1/CCR2 cascade.