IN VIVO STUDIES OF MECHANISMS OF ATHEROGENESIS

我们实验室和其他机构最近的研究补充说， 相当大的力量氧化修饰假说， 动脉粥样硬化 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中， 人，并且动脉粥样硬化病变中至少有一些LDL是 氧化改性的。 我们已经证明普罗布考，一种有效的抗氧化剂， 可减缓WHHL泡沫细胞丰富病变中LDL的降解速率 兔子，也许最重要的是， 动脉粥样硬化。 我们建议将工作重点放在 严格测试体内氧化修饰假说。 最 直接，我们将确定氧化抑制剂的效果， 在WHHL和胆固醇喂养的大鼠中动脉粥样硬化程度的改变 兔，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组成，以及抗氧化剂治疗。 如果低密度脂蛋白的氧化修饰发生在动脉中， 在修饰的脂蛋白的更快速的吸收和降解中， 巨噬细胞泡沫细胞上的清道夫受体。 我们建议进行研究， 测量体内动脉粥样硬化病变中LDL降解的速率， 使用“捕获标签”方法，以确定是否存在 抑制修饰，如上面列出的那些，减缓LDL的速率 损伤的降解。 此外，利用清除剂的竞争性抑制， 受体，例如，马来酰化白蛋白，我们建议量化 损伤中清道夫受体在介导 注射的标记天然LDL的降解。 我们以前的研究是 这与这一想法相一致，但不能证明，高浓度的 低密度脂蛋白积聚在动脉内病变敏感部位， 氧化并产生单核细胞的趋化刺激， 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 病变，以确定何时LDL修饰可能开始开始， 酶可能存在，与什么样的细胞类型，他们是相关的，是否 抑制氧化修饰减少单核细胞的数量 渗透到内皮下空间等。最后，我们已经表明， 用抗-HLA-IgM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-蛋白加合物，特别是，如果染色在 细胞外基质和外膜与脂蛋白相关，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.