Dai Shen, Liu Fengming, Ren Mi, Qin Zhongnan, Rout Namita, Yang Xiao-Feng, Wang Hong, Tomlinson Stephen, Qin Xuebin
Division of Comparative Pathology, Tulane National Primate Research Center, Covington, LA, United States.
Department of Microbiology and Immunology, Tulane University School of Medicine, New Orleans, LA, United States.
Front Cardiovasc Med. 2021 Sep 28;8:731315. doi: 10.3389/fcvm.2021.731315. eCollection 2021.
Previous studies have indicated an important role for complement in atherosclerosis, a lipid-driven chronic inflammatory disease associated to oxidative stress in the vessel wall. However, it remains unclear how complement is activated in the process of atherogenesis. An accepted general model for complement activation in the context of ischemia reperfusion injury is that ischemia induces the exposure of neoepitopes that are recognized by natural self-reactive IgM antibodies, and that in turn activate complement. We investigated whether a similar phenomenon may be involved in the pathogenesis of atherosclerosis, and whether interfering with this activation event, together with inhibition of subsequent amplification of the cascade at the C3 activation step, can provide protection against atherogenesis. We utilized C2scFv-Crry, a novel construct consisting of a single chain antibody (scFv) linked to Crry, a complement inhibitor that functions at C3 activation. The scFv moiety was derived from C2 IgM mAb that specifically recognizes phospholipid neoepitopes known to be expressed after ischemia. C2scFv-Crry targeted to the atherosclerotic plaque of mice, demonstrating expression of the C2 neoepitope. C2scFv-Crry administered twice per week significantly attenuated atherosclerotic plaque in the aorta and aortic root of mice fed with a high-fat diet (HFD) for either 2 or 4 months, and treatment reduced C3 deposition and membrane attack complex formation as compared to vehicle treated mice. C2scFv-Crry also inhibited the uptake of oxidized low-density-lipoprotein (oxLDL) by peritoneal macrophages, which has been shown to play a role in pathogenesis, and C2scFv-Crry-treated mice had decreased lipid content in the lesion with reduced oxLDL levels in serum compared to vehicle-treated mice. Furthermore, C2scFv-Crry reduced the deposition of endogenous total IgM in the plaque, although it did not alter serum IgM levels, further indicating a role for natural IgM in initiating complement activation. Neoepitope targeted complement inhibitors represent a novel therapeutic approach for atherosclerosis.
先前的研究表明补体在动脉粥样硬化中起重要作用，动脉粥样硬化是一种与血管壁氧化应激相关的脂质驱动的慢性炎症性疾病。然而，补体在动脉粥样硬化发生过程中如何被激活仍不清楚。在缺血再灌注损伤背景下，补体激活的一个公认的一般模型是，缺血诱导新表位暴露，这些新表位被天然自身反应性IgM抗体识别，进而激活补体。我们研究了类似现象是否可能参与动脉粥样硬化的发病机制，以及干扰这种激活事件并在C3激活步骤抑制后续级联反应的放大是否能提供抗动脉粥样硬化的保护作用。我们使用了C2scFv-Crry，这是一种新型构建体，由与Crry连接的单链抗体（scFv）组成，Crry是一种在C3激活时起作用的补体抑制剂。scFv部分源自C2 IgM单克隆抗体，该抗体特异性识别已知在缺血后表达的磷脂新表位。C2scFv-Crry靶向小鼠的动脉粥样硬化斑块，证明了C2新表位的表达。每周给药两次C2scFv-Crry可显著减轻高脂饮食（HFD）喂养2或4个月的小鼠主动脉和主动脉根部的动脉粥样硬化斑块，与载体处理的小鼠相比治疗减少了C3沉积和膜攻击复合物的形成。C2scFv-Crry还抑制了腹膜巨噬细胞对氧化低密度脂蛋白（oxLDL）的摄取，氧化低密度脂蛋白已被证明在发病机制中起作用，与载体处理小鼠相比，C2scFv-Crry处理的小鼠病变中的脂质含量降低，血清中oxLDL水平降低。此外，C2scFv-Crry减少了斑块中内源性总IgM的沉积，尽管它没有改变血清IgM水平，进一步表明天然IgM在启动补体激活中起作用。靶向新表位的补体抑制剂代表了一种治疗动脉粥样硬化的新方法。
