Inflammation and Inhibition of Cholesterol Transport

描述(申请人提供)：本提案旨在阐明高密度脂蛋白载脂蛋白A-L在胆固醇反向转运中的作用，因为它与预防炎症和动脉粥样硬化的进展有关。我们建立并鉴定了一种新的双基因敲除动物模型，即低密度脂蛋白受体-/-和载脂蛋白A-I-/-小鼠，以研究和阐明高密度脂蛋白载脂蛋白A-1刺激外周组织胆固醇清除、调节炎症和防止动脉粥样硬化进展的机制。先前对高胆固醇血症小鼠的研究表明，高密度脂蛋白载脂蛋白A-I扮演着两个重要的角色。第一，涉及从外周组织中去除胆固醇，防止在动脉壁内积聚。其次，载脂蛋白A-L调节动脉内皮细胞黏附分子的表达，并调节氧化应激和炎症的诱导。我们小组的初步研究表明，喂食含有0.1%胆固醇和10%脂肪的西方饮食的低密度脂蛋白受体-/-，载脂蛋白A-I-/-小鼠，与只吃低密度脂蛋白受体/-小鼠相比，周围组织中胆固醇的积累大约增加了12倍。因此，在这项提议中，我们计划检验我们的主要假设，即在没有血浆高密度脂蛋白apoA-I的情况下，胆固醇向肝脏的反向运输受到严重限制，允许泡沫细胞衍生的胆固醇酯在周围组织中显著积累，炎症的发生，以及动脉粥样硬化的发展。为了验证这一假设，我们计划测量体内的胆固醇流量，包括摄食和饮食喂养的低密度脂蛋白受体-/-和apoA-I-/-小鼠的吸收、肝脏胆固醇合成和分泌、肝外胆固醇合成、获取和胆固醇周转，并与只喂饲低密度脂蛋白受体-/-和apoA-I-/-的小鼠进行比较。我们还计划通过使用辅助依赖腺病毒技术恢复低密度脂蛋白受体-/-，载脂蛋白A-L-/-小鼠的血浆高密度脂蛋白载脂蛋白A-I浓度，来检验这一假说：抑制低密度脂蛋白受体-/-，载脂蛋白A-I-/-小鼠的胆固醇反向转运和炎症的发生是可逆的。我们相信，这些研究将带来关于载脂蛋白A-L在动脉粥样硬化发展初期的作用的重要新信息，并明确高胆固醇血症与炎症之间的联系以及它们在动脉粥样硬化发病机制中的各自作用。

DESCRIPTION (provided by applicant): This proposal is focused on elucidating the role of high density lipoprotein apolipoprotein A-l in reverse cholesterol transport as it relates to the prevention of inflammation and progression of atherosclerosis. We have produced and characterized a new double knockout animal model, the LDL receptor -/- and apoA-I -/- mouse in order to study and elucidate mechanisms by which HDL apoA-1 stimulates the removal of peripheral tissue cholesterol, modulates inflammation, and prevents the progression of atherosclerosis. Previous studies in hypercholesterolemic mice indicate that HDL apoA-I plays two important roles. The first, involves the removal of cholesterol from peripheral tissues preventing accumulation within the artery wall. Secondly, apoA-l serves to modulate the expression of adhesion molecules on endothelial cells lining the artery and modulates the induction of oxidative stress and inflammation. Preliminary studies from our group have shown that LDL receptor -/-, apoA-I -/- mice fed a Western diet containing 0.1% cholesterol and 10% fat show an approximate approximately 12-fold greater accumulation of cholesterol in peripheral tissues when compared to LDL receptor -/- only mice. Therefore, in this proposal we plan to test our main hypothesis that in the absence of plasma HDL apoA-I reverse cholesterol transport to the liver is severely limited, allowing for dramatic accumulation of foam cell derived cholesterol ester in peripheral tissues, the onset of inflammation, and the development of atherosclerosis. To test this hypothesis, we plan to measure cholesterol flux in vivo including; absorption, hepatic cholesterol synthesis and secretion, extrahepatic cholesterol synthesis, acquisition and cholesterol turnover in chow and diet-fed LDL receptor -/-, apoA-I -/- mice and compare to LDL receptor -/- and apoA-I -/- only mice. We also plan to test the hypothesis that inhibition of reverse cholesterol transport and the onset of inflammation in LDL receptor -/-, apoA-I-/- mice is reversible by restoring plasma HDL apoA-I concentration to LDL receptor -/-, apoA-l -/- mice using helper-dependent adenoviral technology. We believe that these studies will lead to important new information regarding the role of apoA-l in the initial stages of atherosclerosis development and define the link between hypercholesterolemia and inflammation and their respective roles in the pathogenesis of atherosclerosis.