The Role of Oxidative Stress in Endothelial Aging

描述(由申请人提供)： 与年轻的血管细胞相比，衰老的血管细胞对促动脉粥样硬化因子表现出更强的反应性。目前，与年龄相关的血管细胞对动脉粥样硬化刺激敏感性增加的机制还不完全清楚。有迹象表明，随着年龄的增长，活性氧物种(ROS)作为各种刺激的细胞内信使，在血管细胞中诱导动脉粥样硬化反应。在这个项目中，我们将使用过表达铜/锌-超氧化物歧化酶(SOD)或单独表达过氧化氢酶或联合过表达铜/锌-超氧化物歧化酶和过氧化氢酶的转基因小鼠模型来检验以下假设：ROS有助于内皮细胞对氧化脂质的敏感性随年龄的增加而增加。我们之所以选择测试内皮细胞对氧化脂质的敏感性，是因为氧化脂质已被证明具有多种致动脉粥样硬化的作用，例如，诱导EC死亡，增加白细胞与ECs的黏附，以及降低内皮一氧化氮(NO)。我们选择使用过表达铜/锌-超氧化物歧化酶和/或过氧化氢酶的小鼠，因为氧化脂质的动脉粥样硬化作用至少部分与其在内皮细胞中诱导ROS的能力有关，例如，超氧化物和过氧化氢。铜/锌-超氧化物歧化酶是细胞内超氧化物歧化为过氧化氢的主要酶，而过氧化氢酶通过将过氧化氢转化为水来破坏过氧化氢。本项目有三个具体的目标：1)研究铜/锌-超氧化物歧化酶和/或过氧化氢酶过表达是否能减轻与年龄相关的内皮细胞NO代谢的变化；2)研究铜/锌-超氧化物歧化酶和/或过氧化氢酶过表达是否能减少氧化脂质诱导的内皮细胞与内皮细胞黏附的增龄性增加；3)研究铜/锌-超氧化物歧化酶和/或过氧化氢酶过表达是否能减少氧化脂质诱导的内皮细胞凋亡的增龄性增加。如果上述假设是正确的，通过过量表达铜/锌-超氧化物歧化酶和/或过氧化氢酶来减少细胞内的超氧化物歧化和过氧化氢，将减弱与年龄相关的内皮细胞对氧化脂质敏感性的增加。这些信息对于理解ROS在与年龄相关的动脉粥样硬化发展中的作用是重要的，并可能导致潜在的动脉粥样硬化治疗策略。

DESCRIPTION (provided by applicant): Aged vascular cells show greater reactivity to pro-atherogenic factors as compared to their young counterparts. Currently, the mechanism responsible for the age-related increase in the sensitivity of vascular cells to atherogenic stimuli has not been fully understood. There are indicators that reactive oxygen species (ROS), which increase with age, function as intracellular messengers of various stimuli to induce atherogenic responses in vascular cells. In this project, we will use transgenic mouse models that overexpress Cu/Zn-superoxide dismutase (SOD) or catalase alone or overexpress Cu/Zn-SOD and catalase in combination to test the following hypothesis: ROS contribute to the age-related increase in the sensitivity of endothelial cells (ECs) to oxidized lipids. We have chosen to test the sensitivity of ECs to oxidized lipids because oxidized lipids have been shown to have various atherogenic actions, e.g., inducing EC death, increasing leukocyte adhesion to ECs and reducing endothelial nitric oxide (NO). We have chosen to use mice overexpressing Cu/Zn-SOD and/or catalase because the atherogenic action of oxidized lipids is, at least in part, associated with its ability to induce ROS, e.g., superoxide and hydrogen peroxide, in ECs. Cu/Zn-SOD is a major enzyme to convert intracellular superoxide to hydrogen peroxide, while catalase destroys hydrogen peroxide by converting it to water. This project contains three specific aims: 1) to study if overexpression of Cu/Zn-SOD and/or catalase attenuates age-related changes in endothelial NO metabolism; 2) to study if overexpression of Cu/Zn-SOD and/or catalase reduces age-related increase in oxidized lipid-induced adherence of leukocytes to ECs; 3) to study if overexpression of Cu/Zn-SOD and/or catalase reduces age-related increase in oxidized lipid-induced apoptosis in ECs. If the hypothesis described above is correct, reduction in intracellular superoxide and hydrogen peroxide by overexpression of Cu/Zn-SOD and/or catalase will attenuate the age-related increase in the sensitivity of ECs to oxidized lipids. Such information is important for understanding the role of ROS in the age-related development of atherosclerosis and could lead to potential strategies of therapy for atherosclerosis.