Malle E, Waeg G, Schreiber R, Gröne E F, Sattler W, Gröne H J
Institute of Medical Biochemistry and Biochemistry, Karl-Franzens University Graz, Austria.
Eur J Biochem. 2000 Jul;267(14):4495-503. doi: 10.1046/j.1432-1327.2000.01498.x.
The 'oxidation theory' of atherosclerosis proposes that oxidation of low density lipoprotein (LDL) contributes to atherogenesis. Although the precise mechanisms of in vivo oxidation are widely unknown, increasing evidence suggests that myeloperoxidase (MPO, EC 1.11.1.7), a protein secreted by activated phagocytes, generates modified/oxidized (lipo)proteins via intermediate formation of hypochlorous acid (HOCl). In vitro generation of HOCl transforms lipoproteins into high uptake forms for macrophages giving rise to cholesterol-engorged foam cells. To identify HOCl-modified-epitopes in human plaque tissues we have raised monoclonal antibodies (directed against human HOCl-modified LDL) that do not cross-react with other LDL modifications, i.e. peroxynitrite-LDL, hemin-LDL, Cu2+-oxidized LDL, 4-hydroxynonenal-LDL, malondialdehyde-LDL, glycated-LDL, and acetylated-LDL. The antibodies recognized a specific epitope present on various proteins after treatment with OCl- added as reagent or generated by the MPO/H2O2/halide system. Immunohistochemical studies revealed pronounced staining for HOCl-modified-epitopes in fibroatheroma (type V) and complicated (type VI) lesions, while no staining was observed in aortae of lesion-prone location (type I). HOCl-oxidation-specific epitopes are detected in cells in the majority of atherosclerotic plaques but not in control segments. Staining was shown to be inside and outside monocytes/macrophages, endothelial cells, as well as in the extracellular matrix. A similar staining pattern using immunohistochemistry could be obtained for MPO. The colocalization of immunoreactive MPO and HOCl-modified-epitopes in serial sections of human atheroma (type IV), fibroatheroma (type V) and complicated (type VI) lesions provides further convincing evidence for MPO/H2O2/halide system-mediated oxidation of (lipo)proteins under in vivo conditions. We propose that MPO could act as an important link between the development of atherosclerotic plaque in the artery wall and chronic inflammatory events.
动脉粥样硬化的“氧化理论”提出，低密度脂蛋白（LDL）的氧化促进动脉粥样硬化的发生。尽管体内氧化的确切机制尚不清楚，但越来越多的证据表明，髓过氧化物酶（MPO，EC 1.11.1.7），一种由活化吞噬细胞分泌的蛋白质，通过次氯酸（HOCl）的中间形成产生修饰/氧化的（脂蛋白）。体外生成的HOCl将脂蛋白转化为巨噬细胞的高摄取形式，从而产生充满胆固醇的泡沫细胞。为了鉴定人斑块组织中HOCl修饰的表位，我们制备了不与其他LDL修饰交叉反应的单克隆抗体（针对人HOCl修饰的LDL），即过氧亚硝酸盐-LDL、血红素-LDL、Cu2+氧化的LDL、4-羟基壬烯醛-LDL、丙二醛-LDL、糖化-LDL和乙酰化-LDL。在用作为试剂添加的OCl-或由MPO/H2O2/卤化物系统产生的OCl-处理后，这些抗体识别存在于各种蛋白质上的特定表位。免疫组织化学研究显示，在纤维粥样瘤（V型）和复杂（VI型）病变中，HOCl修饰的表位有明显染色，而在易发生病变的部位（I型）的主动脉中未观察到染色。在大多数动脉粥样硬化斑块的细胞中检测到HOCl氧化特异性表位，但在对照节段中未检测到。染色显示在单核细胞/巨噬细胞、内皮细胞内部和外部以及细胞外基质中。使用免疫组织化学可以获得与MPO相似的染色模式。在人动脉粥样瘤（IV型）、纤维粥样瘤（V型）和复杂（VI型）病变的连续切片中，免疫反应性MPO和HOCl修饰的表位的共定位为体内条件下MPO/H2O2/卤化物系统介导的（脂蛋白）氧化提供了进一步令人信服的证据。我们提出，MPO可能是动脉壁中动脉粥样硬化斑块发展与慢性炎症事件之间的重要联系。
