Homocysteine Promotes Migration of Adventitial Fibroblasts via Angiotensin II type 1 Receptor Activation to Aggravate Atherosclerosis

Abstract

BackgroundHyperhomocysteinemia (HHcy) is an independent risk factor for atherosclerosis. However, the mechanisms of HHcy-induced arteriosclerosis are largely unknown. Objective:To clarify the effect of Hcy on adventitial fibroblasts (AFs) and its relation with angiotensin II type 1 receptor (AT1R).Method:The apolipoprotein E gene-deficient mice (Apoe−/−) were used as the murine model for atherosclerosis. HHcy was induced and treated by feeding them 1.5% methionine and telmisartan (gavage 10 mg/kg/d) for 12 weeks, respectively. The AFs and HEK293A cells transfected with the AT1R plasmid were used to investigate the interaction between Hcy and AT1R. All data were expressed as mean ± SEM. The data were analyzed by one-way ANOVA or repeated measurement ANOVA.Results:HHcy aggravated the plaque area of the aortic root and increased the expression of IL-6, MCP-1, and the macrophage marker Mac3 in the plaque and adventitia of the aorta, whereas telmisartan improved this effect. Hyperhomocysteinemia induced the occurrence of the AFs marker protein ER-TR7 in the plaque and the entire layer of the aorta, whereas telmisartan also improved this effect, indicating that hyperhomocysteinemia induced AFs migration and that AT1R mediated this process. Hcy increased the production of AFs H2O2, ROS, and IL-6 of AFs, indicating that Hcy activated the oxidative stress and inflammatory reactions, which may induce cell migration. The subsequent scratch and transwell experiments confirmed that Hcy induced the AFs migration and that telmisartan inhibited this effect. Hcy increased the expression of AFs AT1R and the phosphorylation levels of PKC and ERK1/2 in the AF and HEK293A cells transfected with the AT1R plasmid, whereas telmisartan inhibited this effect, indicating that Hcy activated AT1R intracellular signaling pathway.Conclusion:Hcy promoted adventitial inflammation, induced AFs migration, and aggravated atherosclerosis by activating AT1R.

Calciprotein Particles

“… 184 Stimulated by atherogenic and proinflammatory signaling molecules, adventitial fibroblasts acquire a motile myofibroblastic phenotype 185 , 186 and migrate into the forming neointima. 187 , 188 Myofibroblast are professional extracellular matrix producing cells, that facilitate neointimal growth by the secretion of collagens and other matrix components. 189 Moreover, myofibroblasts secrete a variety of proinflammatory cytokines, 190 which enhance endothelial dysfunction, inflammatory cell recruitment into the neointima, 191 – 193 and smooth muscle cell proliferation.…”