Fang X, Weintraub N L, Rios C D, Chappell D A, Zwacka R M, Engelhardt J F, Oberley L W, Yan T, Heistad D D, Spector A A
Department of Biochemistry, University of Iowa College of Medicine, Iowa City 52242, USA.
Circ Res. 1998 Jun 29;82(12):1289-97. doi: 10.1161/01.res.82.12.1289.
Oxidation of LDL in the subendothelial space has been proposed to play a key role in atherosclerosis. Endothelial cells produce superoxide anions (O2.-) and oxidize LDL in vitro; however, the role of O2.- in endothelial cell-induced LDL oxidation is unclear. Incubation of human LDL (200 microg/mL) with bovine aortic endothelial cells (BAECs) for 18 hours resulted in a 4-fold increase in LDL oxidation compared with cell-free incubation (22.5+/-1.1 versus 6.3+/-0.2 [mean+/-SEM] nmol malondialdehyde/mg LDL protein, respectively; P<0.05). Under similar conditions, incubation of LDL with porcine aortic endothelial cells resulted in a 5-fold increase in LDL oxidation. Inclusion of exogenous copper/zinc superoxide dismutase (Cu/ZnSOD, 100 microg/mL) in the medium reduced BAEC-induced LDL oxidation by 79%. To determine whether the intracellular SOD content can have a similar protective effect, BAECs were infected with adenoviral vectors containing cDNA for human Cu/ZnSOD (AdCu/ZnSOD) or manganese SOD (AdMnSOD). Adenoviral infection increased the content and activity of either Cu/ZnSOD or MnSOD in the cells and reduced cellular O2.- release by two thirds. When cells infected with AdCu/ZnSOD or AdMnSOD were incubated with LDL, formation of malondialdehyde was decreased by 77% and 32%, respectively. Two other indices of LDL oxidation, formation of conjugated dienes and increased LDL electrophoretic mobility, were similarly reduced by SOD transduction. These data suggest that production of O2.- contributes to endothelial cell-induced oxidation of LDL in vitro. Furthermore, adenovirus-mediated transfer of cDNA for human SOD, particularly Cu/ZnSOD, effectively reduces oxidation of LDL by endothelial cells.
已提出内皮下空间中低密度脂蛋白（LDL）的氧化在动脉粥样硬化中起关键作用。内皮细胞可产生超氧阴离子（O2.-）并在体外氧化LDL；然而，O2.-在内皮细胞诱导的LDL氧化中的作用尚不清楚。将人LDL（200μg/mL）与牛主动脉内皮细胞（BAECs）孵育18小时，与无细胞孵育相比，LDL氧化增加了4倍（分别为22.5±1.1与6.3±0.2[平均值±标准误]nmol丙二醛/mg LDL蛋白；P<0.05）。在相似条件下，将LDL与猪主动脉内皮细胞孵育，LDL氧化增加了5倍。培养基中加入外源性铜/锌超氧化物歧化酶（Cu/ZnSOD，100μg/mL）可使BAEC诱导的LDL氧化降低79%。为了确定细胞内超氧化物歧化酶含量是否具有类似的保护作用，用含有人Cu/ZnSOD（AdCu/ZnSOD）或锰超氧化物歧化酶（AdMnSOD）cDNA的腺病毒载体感染BAECs。腺病毒感染增加了细胞中Cu/ZnSOD或MnSOD的含量和活性，并使细胞O2.-释放减少了三分之二。当用AdCu/ZnSOD或AdMnSOD感染的细胞与LDL孵育时，丙二醛的形成分别减少了77%和32%。LDL氧化的另外两个指标，共轭二烯的形成和LDL电泳迁移率的增加，也因超氧化物歧化酶转导而类似地降低。这些数据表明，O2.-的产生在体外有助于内皮细胞诱导的LDL氧化。此外，腺病毒介导的人超氧化物歧化酶cDNA的转移，特别是Cu/ZnSOD，可有效减少内皮细胞对LDL的氧化。
