IN VIVO STUDIES OF MECHANISMS OF ATHEROGENESIS

动脉粥样硬化机制的体内研究

• 批准号: 3735934
• 负责人: THOMAS E CAREW
• 金额: --
• 依托单位: UNIVERSITY OF CALIFORNIA, SAN DIEGO
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/3735934
• 关键词: antioxidants; atherosclerosis; blood lipoprotein metabolism; butylated hydroxytoluene; cell adhesion; chemotaxis; cholesterol; dietary lipid; electron microscopy; genetic strain; immunocytochemistry; in situ hybridization; laboratory rabbit; lipoxygenase; low density lipoprotein; macrophage; monocyte; nutrition related tag; oxidation; oxidoreductase inhibitor; pathogenic diet; peroxidation; receptor; tocopherols; vascular endothelium

Recent studies from our laboratory and from others have added considerable strength to the oxidative modification hypothesis of atherosclerosis. There is now reasonably strong evidence that lipid peroxidation reactions occur in atherosclerotic lesions in animals and In humans, and that at least some of the LDL in atherosclerotic lesions is oxidatively modified. We have shown that probucol, a potent antioxidant, can slow the rate of degradation of LDL In foam cell-rich lesions of WHHL rabbits and, perhaps most importantly, slows the progression of atherosclerosis in these animals. We propose to focus our efforts on critically testing the oxidative modification hypothesis in vivo. Most directly, we will determine the effect of inhibitors of oxidative modification on the extent of atherosclerosis in WHHL and cholesterol-fed rabbits, by treatment with lipoxygenase inhibitors, treatment with a diet that alters LDL fatty acid composition, and treatment with antioxidants. If oxidative modification of LDL occurs In the artery, it should result in a more rapid uptake and degradation of the modified lipoprotein via scavenger receptors on macrophage foam cells. We propose studies to measure the rate of LDL degradation in atherosclerotic lesions in vivo, using the 'trapped label' method, to determine If Interventions which inhibit modification, such as those listed above, slow the rate of LDL degradation in lesions. Also, using competitive inhibition of scavenger receptors by, for example, maleylated albumin, we propose to quantify the contribution of scavenger receptor(s) in lesions in mediating the degradation of injected labeled native LDL. Our previous studies are consistent with the idea, but do not prove, that high concentration of LDL accumulates within the artery at lesion-susceptible sites, undergoes oxidation and generates a chemotactic stimulus for monocytes to penetrate into the subendothelial space. Using immunohistochemical, biochemical and molecular biology techniques, we will examine the natural history of the lesion to define when LDL modification may begin, which pro-oxidant enzymes may be present, with what cell types they are associated, whether inhibition of oxidative modification decreases the number of monocytes penetrating into the subendothelial space, etc. Finally, we have shown immunostaining of atherosclerotic lesions with antibodies against oxidation-specific epitopes on oxidized LDL and propose to characterize these lipid-protein adducts, specifically, if the staining in the extracellular matrix and adventitia are associated with lipoproteins, or are associated with specific matrix proteins.

我们实验室和其他实验室的最新研究补充了 氧化修饰假说具有相当大的说服力 动脉粥样硬化。 现在有相当有力的证据表明脂质 过氧化反应发生在动物和人类的动脉粥样硬化病变中 人类，并且动脉粥样硬化病变中至少有一些 LDL 是 氧化修饰。 我们已经证明普罗布考是一种有效的抗氧化剂， 可以减缓 WHHL 富含泡沫细胞的病变中 LDL 的降解速度 兔子，也许最重要的是，减缓了病情的进展 这些动物的动脉粥样硬化。 我们建议将重点放在 严格测试体内氧化修饰假说。 最多 我们将直接确定氧化抑制剂的效果 WHHL 和胆固醇喂养的动脉粥样硬化程度的改变 兔子，通过脂氧合酶抑制剂治疗，饮食治疗 改变低密度脂蛋白脂肪酸的组成，并用抗氧化剂治疗。 如果 LDL 的氧化修饰发生在动脉中，则应导致 通过更快速地摄取和降解修饰的脂蛋白 巨噬细胞泡沫细胞上的清道夫受体。 我们建议研究 测量体内动脉粥样硬化病变中 LDL 降解率， 使用“陷阱标签”方法来确定是否进行干预 抑制修饰，例如上面列出的修饰，减缓 LDL 的速率 病变退化。 此外，利用清除剂的竞争性抑制 例如，马来酰化白蛋白受体，我们建议量化 病变中清道夫受体在介导 注射的标记天然低密度脂蛋白的降解。 我们之前的研究是 符合这个想法，但不能证明，高浓度 LDL 在动脉内的病变易感部位积聚，经历 氧化并产生趋化刺激单核细胞渗透 进入内皮下空间。 使用免疫组织化学、生化 和分子生物学技术，我们将研究自然历史 损伤来定义 LDL 修饰何时可以开始，其中促氧化剂 可能存在酶，它们与什么细胞类型相关，是否 抑制氧化修饰会减少单核细胞的数量 渗透到内皮下空间等。最后，我们展示了 使用抗体对动脉粥样硬化病变进行免疫染色 氧化 LDL 上的氧化特异性表位并建议表征 这些脂质-蛋白质加合物，具体来说，如果染色 细胞外基质和外膜与脂蛋白相关，或 与特定的基质蛋白相关。