Heinecke J W, Baker L, Rosen H, Chait A
J Clin Invest. 1986 Mar;77(3):757-61. doi: 10.1172/JCI112371.
Extracellular superoxide was detected in cultures of monkey and human arterial smooth muscle cells as indicated by superoxide dismutase inhibitable reduction of cytochrome c. Superoxide production by these cells in the presence of Fe or Cu resulted in modification of low density lipoprotein (LDL). The degree of LDL modification was directly proportional to the rate of superoxide production by cells. Superoxide dismutase (100 micrograms/ml), and the general free radical scavengers butylated hydroxytoluene and butylated hydroxyanisole (50 microM), inhibited Fe- and Cu-mediated modification of LDL by monkey smooth muscle cells, while catalase (100 micrograms/ml) and mannitol (25 mM) had no effect. The chelators desferrioxamine and diethylenetriamine pentaacetic acid completely inhibited Fe- and Cu-promoted modification of LDL, while EGTA had no inhibitory effect. EDTA stimulated Fe-promoted modification in the 1-100 microM range while inhibiting Cu-mediated modification of LDL. LDL modified by smooth muscle cells in the presence of 10 microM Fe or Cu stimulated [14C]oleate incorporation into cholesteryl ester by human macrophages and murine J774 cells to a degree comparable to that produced by acetylated LDL. LDL incubated with smooth muscle cells and metal ions in the presence of superoxide dismutase failed to enhance macrophage cholesteryl ester accumulation. Thus, arterial smooth muscle cells in culture generate superoxide and modify LDL by a superoxide-dependent, Fe or Cu catalyzed free radical process, resulting in enhanced uptake of the modified LDL by macrophages. Neither hydroxyl radicals nor H2O2 are likely to be involved. Superoxide-dependent lipid peroxidation may contribute to biological modification of LDL, resulting in foam cell formation and atherogenesis.
如细胞色素c的超氧化物歧化酶可抑制性还原所示，在猴和人动脉平滑肌细胞培养物中检测到细胞外超氧化物。在铁或铜存在的情况下，这些细胞产生的超氧化物导致低密度脂蛋白（LDL）发生修饰。LDL的修饰程度与细胞产生超氧化物的速率直接成正比。超氧化物歧化酶（100微克/毫升）以及通用自由基清除剂丁基羟基甲苯和丁基羟基茴香醚（50微摩尔）可抑制猴平滑肌细胞对铁和铜介导的LDL修饰，而过氧化氢酶（100微克/毫升）和甘露醇（25毫摩尔）则无作用。螯合剂去铁胺和二乙烯三胺五乙酸完全抑制铁和铜促进的LDL修饰，而乙二醇双四乙酸则无抑制作用。乙二胺四乙酸在1 - 100微摩尔范围内刺激铁促进的修饰，同时抑制铜介导的LDL修饰。在10微摩尔铁或铜存在的情况下，经平滑肌细胞修饰的LDL刺激人巨噬细胞和鼠J774细胞将[14C]油酸掺入胆固醇酯的程度与乙酰化LDL产生的程度相当。在超氧化物歧化酶存在的情况下，与平滑肌细胞和金属离子一起孵育的LDL未能增强巨噬细胞胆固醇酯的积累。因此，培养的动脉平滑肌细胞产生超氧化物，并通过超氧化物依赖性、铁或铜催化的自由基过程修饰LDL，导致巨噬细胞对修饰后的LDL摄取增加。羟基自由基和过氧化氢可能均未参与其中。超氧化物依赖性脂质过氧化可能导致LDL的生物修饰，从而导致泡沫细胞形成和动脉粥样硬化。
