Molecular Basis of Oxidative Modification of LDL

大量证据表明，氧化改性剂的积累和随后的不良加工- 动脉壁巨噬细胞活化的低密度脂蛋白(OxLDL)在高血压的早期阶段起作用。 动脉粥样硬化的形成。低密度脂蛋白的氧化修饰涉及其组成成分载脂蛋白B的衍生化 由脂质过氧化的反应性醛分解产物，包括HNE。蛋白质化学 这些醛的加成反应非常复杂，而且包括交联键。新世纪的重大突破 目前的资助期是发现巨噬细胞摄取oxLDL在很大程度上可能是由 CD36对oxLDL中氧化磷脂的识别。我们进一步发现，类HNE产品 (及其衍生物)由花生四烯基链和亚油基链“镜像”氧化而成 磷脂作为CD36的配体。建议进行进一步的研究，以彻底定义 巨噬细胞识别和积聚oxLDL的结构基础。最近的试点研究 提示氧化低密度脂蛋白中的氧化成分不仅可能干扰体内的脂蛋白加工，而且 氧化低密度脂蛋白暴露下巨噬细胞的胆固醇外流。下一个资助期的一个主要新目标是 阐明oxLDL对胆固醇外流的抑制作用的本质。 我们的工作假设是，低密度脂蛋白的氧化变化有助于其摄取和缺乏 巨噬细胞内的加工，以及oxLDL本身或从其发出的成分抑制一个或多个 更多的胆固醇外流机制，所有这些共同成为泡沫细胞的重要决定因素 队形。我们将继续定义依赖于脂肪氧化的蛋白质加合化学，包括质量 鉴定对修饰特别敏感的巨噬细胞蛋白的光谱方法 这是这些细胞暴露于oxLDL的结果。后一个目标将得到持续发展的帮助。 特定加合物的免疫化学探针，也可用于识别晚期加合物的性质 存在于人类动脉粥样硬化中。拟议的新工作将继续利用汇集的专业知识 邻近研究机构的三名个人调查人员，特别是与申请有关的 用于细胞生物学研究的新型结构特异性试剂和工具。 与公共卫生的相关性 在动脉粥样硬化的初始阶段，血液中主要携带胆固醇的脂蛋白，低密度脂蛋白，变成 氧化损伤(OxLDL)，导致动脉壁内的细胞试图清除oxLDL 然后把它拆开。我们的研究旨在了解为什么人体内胆固醇会积聚 这些细胞无法有效地分解oxLDL并清除释放的胆固醇。

Substantial evidence suggests that the accumulation and subsequent poor processing of oxidatively modi- fied low density lipoprotein (oxLDL) by macrophages in the arterial wall contributes to the initial stages of atherogenesis. Oxidative modification of LDL involves the derivatization of its constituent apolipoprotein B by reactive aldehydic breakdown products of lipid peroxidation, including HNE. The chemistry of protein adduction by these aldehydes is highly complex and includes cross-linking. A major breakthrough of the current funding period was the finding that uptake of oxLDL by macrophages may be largely mediated by the recognition of oxidized phospholipids in oxLDL by CD36. We further discovered that the HNE-like products (and their derivatives) resulting from "mirror-image" oxidation of the arachidonyl and linoleyl chains of phospholipids serve as CD36 ligands. Further studies are proposed to bring thorough definition to the structural basis of oxLDL recognition by and accumulation within macrophage cells. Recent pilot studies suggest that oxidized constituents in oxLDL may interfere not only with lipoprotein processing within, but also cholesterol efflux from macrophage cells exposed to oxLDL. A major new aim of the next funding period is to clarify the nature of the inhibitory effects of oxLDL on cholesterol efflux. Our working hypothesis is that oxidative changes to LDL contribute to its uptake into and deficient processing within macrophage cells, and that oxLDL itself or constituents emanating from it inhibit one or more mechanisms of cholesterol efflux, all of which together act as an important determinant of foam cell formation. We will continue to define lipoxidation-dependent protein adduction chemistry, including mass spectrometric approaches to identifying macrophage proteins that are particularly susceptible to modification as a result of exposure of these cells to oxLDL. This latter aim will be aided by continued development of immunochemical probes for specific adducts, also useful for identifying the nature of late-stage adducts present in human atheroma. The new work proposed continues to take advantage of the pooled expertise of three individual investigators at neighboring research institutions, particularly with respect to the application of novel structurally-specific reagents and tools to cell biological studies. RELEVANCE TO PUBLIC HEALTH In the initial stages of atherosclerosis, the main cholesterol-carrying lipoprotein in blood, LDL, becomes oxidatively damaged (oxLDL), resulting in an attempt by cells lining the artery wall to scavenge the oxLDL and break it down. Our research is aimed at understanding why there is an accumulation of cholesterol in these cells because of their inability to efficiently break down the oxLDL and clear the released cholesterol.