Targeting the Foam Cell to Prevent Atherosclerosis

描述（由申请人提供）：概述脂质巨噬细胞或“泡沫细胞”在动脉粥样硬化的所有阶段起着至关重要的作用，从病变开始到斑块破裂。然而，我们目前的治疗武器库缺乏主要针对泡沫细胞来预防动脉粥样硬化发展的药物。巨噬细胞通过摄取修饰的低密度脂蛋白（mLDL）并在细胞质脂滴（ld）中积累脂质（主要是胆固醇（CHOL）酯（CE））而成为泡沫细胞。ld由中性脂质的核心组成，由磷脂、游离CHOL （FC）和蛋白质组成。主要的ld相关蛋白是pat家族的成员，在巨噬细胞中，最丰富的pat蛋白是脂肪分化相关蛋白（ADFP）。我们已经证明ADFP在泡沫细胞形成中起着关键作用，它的缺失严重限制了巨噬细胞在体外和体内成为泡沫细胞的能力。ADFP在人和小鼠动脉粥样硬化病变中上调，在载脂蛋白e -缺失（apoE-/-）小鼠中ADFP消融具有动脉粥样硬化保护作用。增强巨噬细胞的CHOL外排，例如通过增加血浆中CHOL受体的浓度或通过上调CHOL外排转运蛋白的表达，可以防止动脉粥样硬化。这似乎也是与ADFP缺乏相关的动脉粥样硬化保护机制，因为ADFP缺乏的巨噬细胞不会在ld中以CE的形式积累那么多的CHOL，并且会向细胞外受体排出更多的CHOL。该提案的总体目标是深入了解ADFP在LD生物学，泡沫细胞形成和动脉粥样硬化发展中的作用。在第一个目标中，我们将在体外测试在高脂质应激条件下培养的adfp缺陷巨噬细胞在炎症和凋亡方面的反应。我们还将检查在喂食常规食物的ADFP-/-小鼠中观察到的动脉粥样硬化保护是否也在喂食高脂肪/高胆固醇饮食的小鼠中观察到。在第二个目标中，我们将使用辅助依赖性腺病毒（HDAd）载体系统增加CHOL受体载脂蛋白A1 （apoA1）的血浆浓度，并评估两种不同的增加CHOL外排的方法（即增加细胞外受体和限制细胞储存CHOL的能力）是否具有附加的动脉粥样硬化保护作用。在第三个目标中，我们将进行蛋白质组学分析，以在脂质储存和脂质流出条件下培养的巨噬细胞中找到主要的ld相关蛋白和ADFP相互作用物。我们还将对从表达或不表达ADFP的小鼠病变中直接分离的泡沫细胞进行全局基因表达分析，以确定泡沫细胞如何适应ADFP的缺乏。通过对ADFP在泡沫细胞形成和动脉粥样硬化中的作用的广泛分析，我们希望获得广泛的理解，这可能有助于为针对泡沫细胞预防动脉粥样硬化发展的新策略奠定基础。

DESCRIPTION (provided by applicant): Summary Lipid-laden macrophages or "foam cells" play crucial roles in all the stages of atherogenesis, from lesion initiation to plaque rupture. However, our current therapeutic arsenal lacks of drugs primarily targeting the foam cell to prevent atherosclerosis development. Macrophages become foam cells by the uptake of modified low- density lipoproteins (mLDL) and accumulation of their lipids, mostly cholesterol (CHOL) esters (CE), in cytoplasmic lipid droplets (LDs). LDs consist of a core of neutral lipid stabilized and circumscribed by phospholipids, free CHOL (FC) and proteins. The main structural LD-associated proteins are the members of the PAT-family, and in macrophages the most abundant PAT-protein is adipose differentiation-related protein (ADFP). We have shown that ADFP plays a key role in foam cell formation, and its absence severely restricts the ability of macrophages to become foam cells in vitro and in vivo. ADFP is upregulated in human and mouse atherosclerotic lesions, and ADFP ablation in apolipoprotein E-null (apoE-/-) mice is atheroprotective. Enhancing CHOL efflux from macrophages, e.g. by increasing the concentration in plasma of CHOL acceptors or by upregulating the expression of CHOL efflux transporters, protects against atherosclerosis. This also seems to be the atheroprotective mechanism associated to the lack of ADFP, since ADFP-deficient macrophages do not accumulate as much CHOL in the form of CE in LDs, and efflux more CHOL to extracellular acceptors. The broad goal of this proposal is to gain insight on the role of ADFP in LD biology, foam cell formation and atherosclerosis development. In the first aim, we will test in vitro the response, in terms of inflammation and apoptosis, of ADFP-deficient macrophages cultured under high lipid stress conditions. We will also check if the atheroprotection observed in ADFP-/- mice fed regular chow is also observed when mice are challenged with a high fat/high CHOL diet. In the second aim, we will increase the plasma concentration of the CHOL acceptor apolipoprotein A1 (apoA1) with a helper-dependent adenovirus (HDAd) vector system, and assess whether two different approaches to increase CHOL efflux (i.e. increasing extracellular acceptors and limiting the cell's ability to store CHOL) will have additive atheroprotective effects. In the third aim, we will perform proteomic analyses to find the main LD-associated proteins and ADFP interactors in macrophages cultured under lipid-storing and lipid-efflux conditions. We will also perform a global gene expression analysis in foam cells directly isolated from lesions of mice that do or do not express ADFP to determine how the foam cell adjusts to the lack of ADFP. From this broad-based analysis of the role of ADFP in foam cell formation and atherosclerosis we expect to obtain a breadth of understanding that may help to set- up the bases for novel strategies to target the foam cell to prevent atherosclerosis development.