Atherogenic mechanism of lipid peroxidation-derived aldehydes

描述（由申请人提供）：该项目的总体目标是了解脂质过氧化衍生醛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，我们提出验证巨噬细胞中脂质衍生醛的积累诱导内质网（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的假设。该项目的具体目标是：(1)描述内质网应激和UPR对醛介导的巨噬细胞激活的贡献；(2)阐明UPR在动脉粥样硬化发生中的作用；(3)研究醛代谢在动脉粥样硬化病变中预防内质网应激和UPR的作用。为了实现这些目标，我们将研究小鼠骨髓源性巨噬细胞暴露于模型脂质衍生醛（HNE或POVPC）是否会诱导内质网应激和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激活，以及它们如何促进巨噬细胞激活、泡沫细胞形成和凋亡。为了研究内质网应激和UPR在动脉粥样硬化病变形成过程中的作用，我们将确定apoe缺失小鼠动脉病变中内质网应激和UPR的阶段特异性变化。为了探究因果关系，我们将研究是否使用化学伴侣治疗，帮助蛋白质折叠，会减少病变的形成和提高斑块的稳定性。此外，我们将测试激活因子3 （ATF3）的基因消融是否会增加病变进展和炎症，ATF3是一种由脂质醛显著诱导的ubr应答基因。为了阐明醛在动脉粥样硬化病变中诱导内质网应激中的作用，我们将研究醛糖还原酶（一种能够解毒HNE和POVPC的酶）的基因缺失或过表达如何影响醛糖诱导的巨噬细胞激活和泡沫细胞形成，以及apoe缺失小鼠动脉病变中内质网应激、UPR诱导的内质网应激。这个项目的成功完成可能会导致更好地理解脂质衍生醛影响动脉粥样硬化的机制，以及如何预防或治疗最小化这些醛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. 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.