Ascorbylation of Oxidized Lipids and Atherosclerosis

描述(由申请人提供)：脂质过氧化(LPO)过程与动脉粥样硬化的起始和早期进展阶段密切相关。维生素C的抗氧化活性有助于终止自由基介导的LPO过程。然而，抗坏血酸也通过脂质氢过氧化物的单电子还原促进细胞毒性和潜在的致动脉粥样硬化的LPO产物的形成。因此，维生素C在自由基介导的脂质过氧化过程中的总体作用仍有待确定。 这项应用的目的是确定维生素C在脂质过氧化过程中的作用，以及这种作用如何促进血管内皮细胞和血管平滑肌细胞对氧化应激的总体反应。需要评估的中心假设是，维生素C通过抗坏血酸(共轭形成)消除有害的LPO产物，如4-羟基-2-壬烯醛(HNE)，从而在血管壁上产生全面的抗动脉粥样硬化作用。我们进一步假设，在健康的人受到急性氧化应激伤害后，抗坏血酸会导致这些维生素C结合物的血浆水平升高，而在慢性氧化应激条件下，如吸烟和冠心病，抗坏血酸会受到影响。 我们的三个具体目标是：(1)确定抗坏血酸HNE的生物来源，并表征其处置、代谢和排泄，(2)表征氧化脂质及其抗坏血酸结合物在人主动脉内皮细胞(HAECs)和血管平滑肌细胞(VSMCs)中引发的致动脉粥样硬化反应，以及(3)确定吸烟者、补充和不补充维生素C以及冠状动脉造影证实的冠状动脉疾病患者中抗坏血酸LPO产物水平与氧化应激的关系。 这项应用中提出的研究意义重大，因为通过抗坏血酸化消除亲电性LPO产物将对目前对由脂质过氧化过程加剧的疾病的理解产生深远影响，如动脉粥样硬化。这个项目有助于我们确定脂质过氧化在炎症和年龄相关疾病中的作用，以及如何通过治疗或饮食干预来调节其影响。

DESCRIPTION (provided by applicant): Lipid peroxidation (LPO) processes are closely associated with the initiation and early progression stages of atherosclerosis. The antioxidant activity of vitamin C contributes to the termination of radical-mediated LPO processes. However, ascorbic acid also promotes the formation of cytotoxic and potentially atherogenic LPO products via one-electron reduction of lipid hydroperoxides. Thus, the overall role of vitamin C in radical- mediated lipid peroxidation processes remains to be established. The objective for this application is to determine the role of vitamin C in lipid peroxidation processes and how this role contributes to the overall response of vascular endothelial cells and vascular smooth muscle cells to oxidative stress. The central hypothesis to be evaluated is that vitamin C eliminates harmful LPO products, such as 4-hydroxy-2-nonenal (HNE), through ascorbylation (conjugate formation), resulting in an overall anti-atherogenic effect on the vascular wall. We further hypothesize that ascorbylation leads to enhanced plasma levels of these vitamin C conjugates after an acute oxidative stress insult in healthy individuals, whereas ascorbylation is compromised under conditions of chronic oxidative stress, such as smoking and coronary heart disease. Our three Specific Aims are: (1) Identify the biological source of ascorbylated HNE and characterize its disposition, metabolism and excretion, (2) Characterize the atherogenic responses elicited by oxidized lipids and their ascorbyl conjugates in human aortic endothelial cells (HAECs) and in vascular smooth muscle cells (VSMCs), and (3) Determine the relationship between ascorbylated LPO product levels and oxidative stress in smokers, with and without vitamin C supplementation, and in patients with angiographically confirmed coronary artery disease. The research proposed in this application is significant, because elimination of electrophilic LPO products through ascorbylation will have a profound impact on the current understanding of diseases that are exacerbated by lipid peroxidation processes, such as atherosclerosis. This project contributes to our long- term goal to determine the role of lipid peroxidation in inflammatory and age-related disease and how its effects can be modulated by therapeutic or dietary intervention.