Atherogenic mechanism of lipid peroxidation-derived aldehydes

描述（由申请人提供）：本项目的总体目标是了解脂质过氧化物衍生的醛类在动脉粥样硬化中的作用。醛类如4-羟基壬烯醛（HNE）和1-棕榈酰-2-（5-氧代戊酰）-3-甘油-磷脂酰胆碱（POVPC）是LDL氧化产生的主要生物活性产物。基于支持性的初步研究，我们建议检验假设，即在巨噬细胞中脂质衍生的醛类的积累诱导内质网（ER）应激并触发未折叠蛋白反应（UPR），导致细胞因子产生和泡沫细胞形成。本项目的具体目标是：（1）描述ER应激和UPR对过氧化物介导的巨噬细胞活化的贡献;（2）阐明UPR在调节动脉粥样硬化形成中的作用;（3）检查醛代谢在预防动脉粥样硬化病变中的ER应激和UPR中的作用。为了实现这些目标，我们将研究小鼠骨髓衍生的巨噬细胞暴露于模型脂质衍生的醛- HNE或POVPC是否诱导ER应激和UPR。我们将确定这种反应的程度和性质，并确定哪些特定的UPR依赖性信号通路被醛类激活，以及它们如何促进巨噬细胞活化，泡沫细胞形成和凋亡。为了研究ER应激和UPR在动脉粥样硬化病变形成过程中的作用，我们将确定apoE基因敲除小鼠动脉病变中ER应激和UPR的阶段特异性变化。为了探讨因果关系，我们将研究是否治疗与化学分子伴侣，这有助于蛋白质折叠，将减少病变的形成和改善斑块的稳定性。此外，我们将测试激活因子3（ATF 3）的基因消融是否会增加病变进展和炎症，ATF 3是一种由脂质醛显著诱导的UPR应答基因。为了阐明醛类在动脉粥样硬化病变中诱导ER应激的作用，我们将研究醛糖还原酶（一种能解毒HNE和POVPC的酶）的基因缺失或过表达如何影响apoE基因缺失小鼠动脉病变中的ER应激、UPR诱导以及培养中的雌二醇诱导的巨噬细胞活化和泡沫细胞形成。该项目的成功完成可能会导致更好地了解脂质衍生的醛类影响动脉粥样硬化形成的机制，以及如何预防或治疗这些醛类的影响，以减少动脉粥样硬化。

DESCRIPTION (provided by applicant): The overall goal of this project is to understand the role of lipid peroxidation-derived aldehydes in atherosclerosis. Aldehydes such as 4-hydroxynonenal (HNE) and 1-palmitoyl-2-(5-oxovaleroyl)-3- glycero- phosphatidyl choline (POVPC) are the major bioactive products generated from the oxidation of LDL. Based on supportive preliminary studies, we propose to test hypothesis that accumulation of lipid-derived aldehydes in macrophages induces endoplasmic reticulum (ER) stress and triggers the unfolded protein response (UPR), leading to cytokine production and foam cell formation. The specific aims of this project are to: (1) delineate the contribution of ER stress and UPR to aldehyde-mediated macrophage activation; (2) elucidate the role of UPR in regulating atherogenesis; and (3) examine the role of aldehyde metabolism in preventing ER stress and UPR in atherosclerotic lesions. To accomplish these aims, we will examine whether exposure of murine bone marrow derived macrophages to model lipid-derived aldehydes - HNE or POVPC induces ER stress and UPR. We will determine the extent and the nature of this response and identify which specific UPR-dependent signaling pathways are activated by aldehydes and how they contribute to macrophage activation, foam cell formation, and apoptosis. To examine the role of ER-stress and UPR during atherosclerotic lesion formation, we will determine stage-specific changes in ER stress and UPR in the arterial lesions of apoE-null mice. To probe causality, we will examine whether treatment with chemical chaperones, which assist protein folding, would decrease lesion formation and improve plaque stability. In addition, we will test whether genetic ablation of activating factor 3 (ATF3), a UPR-responsive gene, which is dramatically induced by lipid aldehydes, increases lesion progression and inflammation. To elucidate the role of aldehydes in inducing ER stress in atherosclerotic lesions, we will examine how genetic deletion or overexpression of aldose reductase, an enzyme which detoxifies both HNE and POVPC, affects aldehyde-induced macrophage activation and foam cell formation in culture and ER stress, UPR induction in the arterial lesions of apoE-null mice. Successful completion of this project may lead to a better understanding of the mechanisms by which lipid-derived aldehydes affect atherogenesis and how the effects of these aldehydes could be prevented or therapeutically minimized to decrease atherosclerosis.