IN VIVO STUDIES OF MECHANISMS OF ATHEROGENESIS

我们实验室和其他实验室最近的研究增加了 氧化修饰假说有相当大的说服力 动脉硬化。现在有相当有力的证据表明， 过氧化反应发生在动物的动脉粥样硬化病变和 至少动脉粥样硬化病变中的部分低密度脂蛋白是 氧化改性。我们已经证明了普罗布考，一种有效的抗氧化剂， 可以减缓WHHL泡沫细胞丰富的病变中低密度脂蛋白的降解速度 而且，也许最重要的是，它减缓了 这些动物的动脉粥样硬化。我们建议将我们的努力集中在 在体内批判性地检验氧化修饰假说。多数 我们将直接确定氧化抑制剂的效果 高脂饮食和高胆固醇饮食对动脉粥样硬化程度的影响 兔，用脂氧合酶抑制剂治疗，用饮食治疗 这会改变低密度脂蛋白的脂肪酸组成，并用抗氧化剂进行治疗。 如果低密度脂蛋白的氧化修饰发生在动脉中，应该会导致 通过更快地吸收和降解修饰的脂蛋白 巨噬细胞泡沫细胞上的清道夫受体。我们建议进行研究以 测量体内动脉粥样硬化病变中低密度脂蛋白的降解率， 使用“陷阱标签”方法，以确定哪些干预措施 抑制修饰，如上面列出的那些，减缓低密度脂蛋白的速率 病变中的降解。此外，使用清道夫的竞争抑制 例如，通过顺丁烯二酸化白蛋白，我们建议量化 清道夫受体(S)在皮损中的作用 注射标记的天然低密度脂蛋白的降解。我们之前的研究是 与这个想法一致，但不能证明，高度集中的 低密度脂蛋白在动脉中聚集在病变易感部位，经历 氧化并产生趋化刺激使单核细胞穿透 进入内皮下间隙。利用免疫组织化学、生化 和分子生物学技术，我们将研究自然历史 定义何时可以开始低密度脂蛋白修饰的病变，哪种促氧化剂 酶可能存在，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 穿透到内皮下间隙等。最后，我们展示了 抗动脉粥样硬化病变的抗体免疫染色 氧化型低密度脂蛋白的氧化特异性表位及其特征 具体地说，这些脂质-蛋白质加合物，如果在 细胞外基质和外膜与脂蛋白有关，或 与特定的基质蛋白有关。

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.