Oxidant resistant apoA1 in reverse cholesterol transport, inflammation and atherosclerosis

摘要 高密度脂蛋白胆固醇(高密度脂蛋白-胆固醇)水平高与心血管风险降低相关 流行病学研究中的疾病(CVD)。尽管几种机制可能在高密度脂蛋白的保护作用中发挥作用 效应，高密度脂蛋白及其主要蛋白质成分载脂蛋白AI(ApoA1)是反转的关键成分 胆固醇转运(RCT)途径，在该途径中，胆固醇从外周组织中被移除并转移到 用于排泄的肝脏。在RCT途径的第一步，低脂的apoA1作为细胞的受体 胆固醇和磷脂通过细胞膜蛋白ABCA1产生新生的高密度脂蛋白。然而，不是 所有的高密度脂蛋白都是相同的，几项研究报告说，患有冠状动脉疾病的人有 高密度脂蛋白“功能失调”，不再具有动脉粥样硬化保护作用。动脉粥样硬化是一种高度氧化的病变。 环境，人体损伤含有高水平的抗菌酶髓过氧化物酶(MPO)， 我们和其他人已经证明，它可以氧化载脂蛋白A1并损害其功能。我们确定这四个人 人载脂蛋白A1(h-apoA1)中的色氨酸残基是其MPO介导的胆固醇受体丢失的关键 功能。我们创造了一个新的4WF h-apoA1变异体，其中所有四个色氨酸残基都被 苯丙氨酸，它能抵抗MPO介导的功能丧失。我们创造并描述了转基因 表达高水平4WF h-apoA1亚型的小鼠，并发现这些小鼠对 发炎。我们还创造了人MPO转基因小鼠，它过度表达MPO，可以进一步 酵母多糖处理诱导的。在这里，我们建议表征h-apoA1修饰在小鼠模型和 如果这些受到炎性刺激的调节。我们还将测试抗氧化性4WF apoA1 异构体可以更好地预防炎症和脓毒症，促进胆固醇的反向运输，延缓 在过度表达MPO的小鼠中，促进动脉粥样硬化的消退，从而产生 一种与人体损伤相似的氧化环境。从机制上讲，我们将决定 4WF亚型保护小鼠免受急性期反应，并检查4WF亚型是否更好地防止 骨髓中髓系细胞的增殖和动员导致单核细胞增多和中性粒细胞增多 与动脉粥样硬化的进展有关。

Abstract High levels of high density lipoprotein-cholesterol (HDL-C) are associated with lowered risk for cardiovascular disease (CVD) in epidemiological studies. Although several mechanisms may play a role in HDL’s protective effect, HDL and its major protein constituent, apolipoprotein-AI (apoA1), are critical components of the reverse cholesterol transport (RCT) pathway, in which cholesterol is removed from peripheral tissues and transferred to the liver for excretion. In the first step of the RCT pathway, lipid-poor apoA1 acts as an acceptor for cell cholesterol and phospholipids via the cell membrane protein ABCA1, generating nascent HDL. However, not all HDL is equivalent, and several studies have reported that individuals with coronary artery disease have HDL that is “dysfunctional” and no longer atheroprotective. The atherosclerotic lesion is a highly oxidative environment, and human lesions contain high levels of the antimicrobial enzyme myeloperoxidase (MPO), which we and others have shown can oxidize apoA1 and impair its function. We determined that the four tryptophan residues in human apoA1 (h-apoA1) are crucial in its MPO mediated loss of cholesterol acceptor function. We created a novel 4WF h-apoA1 variant, in which all four tryptophan residues are replaced by phenylalanine, which is resistant to MPO-mediated loss of function. We created and characterized transgenic mice that express high levels of the 4WF h-apoA1 isoform and found that these mice were resistant to inflammation. We also created human MPO transgenic mice, which over express MPO that can be further induced by zymosan treatment. Here we propose to characterize h-apoA1 modifications in mouse models and if these are modulated by inflammatory stimuli. We will also test whether the oxidant resistant 4WF apoA1 isoform can better protect from inflammation and sepsis, promote reverse cholesterol transport, delay atherosclerosis progression, and promote atherosclerosis regression in mice that over express MPO, creating an oxidative environment similar to that found in human lesions. Mechanistically, we will determine how the 4WF isoform protects mice from an acute phase response, and examine if the 4WF isoform better prevents myeloid cell proliferation and mobilization from the bone marrow leading to monocytosis and neutrophilia that are associated with atherosclerosis progression.