Role of apolipoprotein E4 in the progression and regression of atherosclerosis

描述(申请人提供)：动脉粥样硬化及其并发症在美国仍然是导致死亡和残疾的主要原因。尽管促进动脉粥样硬化的消退已成为治疗动脉粥样硬化的一种有前景的策略，但协调这一临床相关过程的分子和细胞机制尚不清楚。此外，载脂蛋白4(ApoE4)等位基因诱发有症状的动脉粥样硬化的机制，以及它是否会损害其在降低血脂后的消退，在很大程度上仍不清楚。为了填补这些知识空白，我们提出了一系列实验，使用我们实验室开发的载脂蛋白E4、条件性载脂蛋白E表达、可逆性高脂血症和动脉粥样硬化消退的基因工程小鼠模型。ApoeR61h/h亚型小鼠表达水平降低的类apoE4形式的小鼠apoE(Arg-61 apoE)，复制了人类apoE4的一种独特的生物物理特征，称为“结构域相互作用”。我们以前的研究表明，Arg-61 apoE中的结构域相互作用足以在高脂血症小鼠血浆中复制人apoE4的VLDL结合偏好。此外，我们在ApoeR61h/h小鼠中条件表达apoE的研究最近证实，apoE除了降低血浆胆固醇水平外，还存在促进动脉粥样硬化消退的作用。 这项建议中详细介绍的实验将利用ApoeR61h/h小鼠以及该模型的新变体，来研究在高脂血症背景下，载脂蛋白E在血浆中的积累和巨噬细胞衍生的载脂蛋白E在皮损中调节动脉粥样硬化的发生和发展的机制。我们还将检验这一假设，即Arg-61 apoE中apoE4结构域的相互作用将加速动脉粥样硬化的进展，并在持续降脂后损害其消退。最后，我们将检验这一假设，即在动脉粥样硬化消退过程中，apoE表达水平影响单核细胞向已建立的病变的迁移，以及巨噬细胞以异构体特异性的方式从病变中流出。 我们的长期目标是阐明载脂蛋白E亚型调节动脉粥样硬化进展和消退的分子和细胞机制。更好地了解这些机制将有助于引入新一代分子疗法来对抗动脉粥样硬化，特别是在占全球人口20%的载脂蛋白E4携带者中。

DESCRIPTION (provided by applicant): Atherosclerosis and its complications remain leading causes of death and disability in the United States. Although promoting the regression of atherosclerosis has emerged as a promising treatment strategy for atherosclerosis, the molecular and cellular mechanisms that orchestrate this clinically relevant process are poorly understood. Moreover, the mechanisms by which the apolipoprotein 4 (apoE4) allele predisposes to symptomatic forms of atherosclerosis and whether it can impair its regression following plasma lipid lowering, remains largely unknown. To fill these gaps of knowledge, we propose a series of experiments with genetically engineered murine models of apoE4, conditional apoE expression, reversible hyperlipidemia, and atherosclerosis regression developed in our laboratory. Hypomorphic ApoeR61h/h mice express reduced levels of an apoE4-like form of murine apoE (Arg-61 apoE) that reproduces a unique biophysical feature of human apoE4 called "domain interaction". Our previous studies have shown that domain interaction in Arg- 61 apoE is sufficient to reproduce the VLDL-binding preference of human apoE4 in hyperlipidemic mouse plasma. Moreover, our studies of conditional expression of apoE in ApoeR61h/h mice has recently established the existence of a role for apoE in promoting the regression of atherosclerosis beyond lowering plasma cholesterol levels. Experiments detailed in this proposal will make use of ApoeR61h/h mice, as well as new variants of this model, to investigate mechanisms by which apoE accumulation in plasma and macrophage-derived apoE in lesions regulate the onset and progression of atherosclerosis in the setting of hyperlipidemia. We will also test the hypothesis that apoE4 domain interaction in Arg-61 apoE will accelerate the progression of atherosclerosis and impair its regression following sustained lipid lowering. Lastly, we will test the hypothesis that apoE expression levels influence the migration of monocytes into established lesions, and the egress of macrophages from lesions during the regression of atherosclerosis in an isoform-specific manner. Our long term goal is to clarify the molecular and cellular mechanisms by which apoE isoforms regulate the progression and regression of atherosclerosis. A better understanding of these mechanisms would help usher in a new generation of molecular therapies to fight atherosclerosis, particularly among apoE4 carriers who represent 20% of the global population.