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。 公共卫生相关性：氧化脂质被认为在动脉粥样硬化病变的形成中起着关键作用，然而，这些脂质或其产物诱导血管损伤、促进斑块形成或破裂的机制尚不清楚。我们的研究旨在验证巨噬细胞中脂质衍生的醛类积累诱导内质网（ER）应激并触发未折叠蛋白反应（UPR）的假设。我们认为，脂质衍生的醛类诱导转录因子3（ATF 3），这是与报警相关联的UPR和遗传消融的ATF 3加剧和药理学抑制ER应激减少动脉粥样硬化形成。要检查醛确实是因果关系参与ER应激和动脉粥样硬化，我们将检查是否巨噬细胞特异性过表达或缺失的醛糖还原酶，将有毒的醛转化为无害的醇，影响其致动脉粥样硬化的作用。从这个项目中获得的结果将有助于更好地理解，并可能，减少或管理动脉粥样硬化的新的治疗策略。

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. PUBLIC HEALTH RELEVANCE: Oxidized lipids have been suggested to play a pivotal role in the formation of atherosclerotic lesions, nevertheless, the mechanisms by which these lipids or their products induce vascular injury, and promote plaque formation or rupture are unknown. Our studies are designed to test the hypothesis that accumulation of lipid-derived aldehydes in macrophages induces endoplasmic reticular (ER) stress and triggers unfolded protein response (UPR). We propose that lipid-derived aldehydes induce the transcription factor 3 (ATF3), which is associated with the alarm phase of UPR and genetic ablation of ATF3 exacerbates and pharmacological inhibition of ER-stress decreases atherogenesis. To examine that aldehydes are indeed causally involved in ER-stress and atherogenesis, we will examine whether macrophage specific overexpression or deletion of aldose reductase, which converts toxic aldehydes to innocuous alcohols, affects their atherogenic effects. Results obtained from this project will help in developing a better understanding, and potentially, novel therapeutic strategies for decreasing or managing atherosclerosis.