Data_Sheet_1_Differential Role for Activating FcγRIII in Neointima Formation After Arterial Injury and Diet-Induced Chronic Atherosclerosis in Apolipoprotein E-Deficient Mice.pdf

Atherogenesis and arterial remodeling following mechanical injury are driven by inflammation and mononuclear cell infiltration. The binding of immune complexes (ICs) to immunoglobulin (Ig)-Fc gamma receptors (FcγRs) on most innate and adaptive immune cells induces a variety of inflammatory responses that promote atherogenesis. Here, we studied the role of FcγRIII in neointima formation after arterial injury in atherosclerosis-prone mice and compared the outcome and mechanism to that of FcγRIII in diet-induced “chronic” atherosclerosis. FcγrIII–/–/Apoe–/– and control Apoe–/– mice were subjected to wire-induced endothelial denudation of the carotid artery while on high-fat diet (HFD). FcγrIII deficiency mitigated neointimal plaque formation and lesional macrophage accumulation, and enhanced neointimal vascular smooth muscle cell (VSMC) numbers. This went along with a reduced expression of tumor necrosis factor-α (TNF-α), monocyte chemoattractant protein-1 (MCP-1/CCL2), and vascular cell adhesion molecule-1 (VCAM-1) in the neointimal lesions. Interestingly, in a chronic model of diet-induced atherosclerosis, we unraveled a dichotomic role of FcγRIII in an early versus advanced stage of the disease. While FcγrIII deficiency conferred atheroprotection in the early stage, it promoted atherosclerosis in advanced stages. To this end, FcγrIII deficiency attenuated pro-inflammatory responses in early atherosclerosis but promoted these events in advanced stages. Analysis of the mechanism(s) underlying the athero-promoting effect of FcγrIII deficiency in late-stage atherosclerosis revealed increased serum levels of anti-oxidized-LDL immunoglobulins IgG2c and IgG2b. This was paralleled by enhanced lesional accumulation of IgGs without affecting levels of complement-activated products C5a or C5ar1, FcγRII, and FcγRIV. Moreover, FcγrIII-deficient macrophages expressed more FcγrII, Tnf-α, and Il-1β mRNA when exposed to IgG1 or oxLDL-IgG1 ICs in vitro, and peripheral CD4+ and CD8+ T-cell levels were altered. Collectively, our data suggest that deficiency of activating FcγRIII limits neointima formation after arterial injury in atherosclerosis-prone mice as well as early stage chronic atherosclerosis, but augments late-stage atherosclerosis suggesting a dual role of FcγRIII in atherogenic inflammation.

动脉损伤后，动脉重塑与粥样硬化形成受炎症和单核细胞浸润驱动。免疫复合物（ICs）与多数先天性和适应性免疫细胞上的免疫球蛋白（Ig）-Fcγ受体（FcγRs）结合，诱导一系列炎症反应，这些反应促进粥样硬化进程。本研究旨在探讨FcγRIII在动脉粥样硬化易感小鼠动脉损伤后新内膜形成中的作用，并将其结果和机制与饮食诱导的“慢性”粥样硬化中FcγRIII的作用进行比较。在给予高脂肪饮食（HFD）的同时，FcγrIII–/–/Apoe–/–和对照Apoe–/–小鼠接受了由电线诱导的颈动脉内皮剥脱。FcγrIII的缺乏减轻了新内膜斑块的形成和损伤部位的巨噬细胞积累，并增加了新内膜血管平滑肌细胞（VSMC）的数量。这伴随着新内膜损伤中肿瘤坏死因子-α（TNF-α）、单核细胞趋化蛋白-1（MCP-1/CCL2）和血管细胞粘附分子-1（VCAM-1）表达的降低。有趣的是，在饮食诱导的粥样硬化的慢性模型中，我们揭示了FcγRIII在疾病早期与晚期之间的对立作用。尽管FcγrIII缺乏在早期阶段提供了粥样硬化保护，但在晚期阶段却促进了粥样硬化的发展。为此，FcγrIII缺乏减轻了早期粥样硬化的促炎反应，但在晚期阶段却促进了这些事件。分析FcγrIII缺乏在晚期粥样硬化中促进粥样硬化的潜在机制，发现血清中抗氧化的低密度脂蛋白（LDL）免疫球蛋白IgG2c和IgG2b水平升高。这与损伤部位IgGs的累积增强相伴随，而不影响补体激活产物C5a或C5ar1、FcγRII和FcγRIV的水平。此外，在体外暴露于IgG1或oxLDL-IgG1 ICs时，FcγrIII缺陷型巨噬细胞表达更多的FcγrII、Tnf-α和Il-1β mRNA，并且外周CD4+和CD8+ T细胞水平发生改变。综上所述，我们的数据表明，激活型FcγRIII的缺乏可限制动脉粥样硬化易感小鼠动脉损伤后以及早期慢性粥样硬化阶段的新内膜形成，但会加剧晚期粥样硬化，表明FcγRIII在粥样硬化性炎症中具有双重作用。