Folcik V A, Nivar-Aristy R A, Krajewski L P, Cathcart M K
Department of Cell Biology, Cleveland Clinic Foundation, Ohio 44195, USA.
J Clin Invest. 1995 Jul;96(1):504-10. doi: 10.1172/JCI118062.
Oxidized LDL is present in human atherosclerotic lesions, but the mechanisms responsible for oxidation in vivo have not been definitively demonstrated. Circumstantial evidence has implicated the enzyme 15-lipoxygenase as a contributor to the formation of oxidized lipids in this disease. To assess whether oxidized lipids are indeed formed by the action of 15-lipoxygenase on polyunsaturated fatty acids (PUFAs) in vivo, we have used a sensitive and specific method (chiral phase HPLC) to analyze the lipid oxidation products present in human atherosclerotic lesions. Human 15-lipoxygenase is an omega-6 lipoxygenase that has previously been shown to oxidize esterified PUFA in a stereospecific manner, forming predominantly cholesteryl hydroperoxy-octadecadienoate (13(S)-HPODE) from cholesteryl linoleate substrate in LDL. This property allows its activity to be distinguished from nonenzymatic oxidation, which results in the formation of equal quantities of the S and R stereoisomers of the same oxidation product. A total of 80 specimens of human atherosclerotic plaque were analyzed. Esterified, oxidized linoleate was purified from human atherosclerotic lesions and from LDL oxidized by copper, and the chirality of these oxidation products was compared. There was significantly greater stereospecificity of oxidation in the oxidized linoleate from human atherosclerotic lesions. Even greater stereospecificity was detected in the HPODE derived from cholesteryl ester, purified from human lesions. Cholesteryl HPODE is the primary oxidation product from cholesteryl linoleate, the major esterified PUFA that accumulates in atherosclerotic vessels. Cholesteryl HPODE and its reduced form, cholesteryl hydroxy-octadecadienoate, were detected in all lesions analyzed. Neither the stereospecificity of oxidation nor the percentage of available substrate oxidized to primary oxidation products was correlated with the stage of disease of the lesions examined. We conclude that 15-lipoxygenase contributes to the formation of oxidized lipids in human atherosclerotic lesions.
氧化型低密度脂蛋白存在于人类动脉粥样硬化病变中，但体内氧化的机制尚未得到明确证实。间接证据表明，15-脂氧合酶是该疾病中氧化脂质形成的一个促成因素。为了评估氧化脂质是否确实是由15-脂氧合酶在体内对多不饱和脂肪酸（PUFA）的作用形成的，我们使用了一种灵敏且特异的方法（手性相高效液相色谱法）来分析人类动脉粥样硬化病变中存在的脂质氧化产物。人类15-脂氧合酶是一种ω-6脂氧合酶，此前已证明它能以立体特异性方式氧化酯化的PUFA，主要从低密度脂蛋白中的胆固醇亚油酸酯底物形成胆固醇氢过氧化十八碳二烯酸酯（13(S)-HPODE）。这一特性使其活性能够与非酶促氧化区分开来，非酶促氧化会导致形成等量的相同氧化产物的S型和R型立体异构体。总共分析了80份人类动脉粥样硬化斑块标本。从人类动脉粥样硬化病变和经铜氧化的低密度脂蛋白中纯化出酯化的、氧化的亚油酸酯，并比较这些氧化产物的手性。来自人类动脉粥样硬化病变的氧化亚油酸酯中的氧化立体特异性明显更高。在从人类病变中纯化出的胆固醇酯衍生的HPODE中检测到了更高的立体特异性。胆固醇氢过氧化十八碳二烯酸酯是胆固醇亚油酸酯的主要氧化产物，胆固醇亚油酸酯是在动脉粥样硬化血管中积累的主要酯化PUFA。在所有分析的病变中都检测到了胆固醇氢过氧化十八碳二烯酸酯及其还原形式胆固醇羟基十八碳二烯酸酯。氧化的立体特异性或氧化为主要氧化产物的可用底物百分比均与所检查病变的疾病阶段无关。我们得出结论，15-脂氧合酶促成了人类动脉粥样硬化病变中氧化脂质的形成。
