中文摘要：

本研究旨在探讨氧化低密度脂蛋白（oxidized low density lipoprotein,ox-LDL）对人脐静脉内皮细胞（human umbilical vein endothelial cells,HUVECs）色素上皮衍生因子（pigment epithelium-derived factor,PEDF）表达水平的作用。体外培养HUVECs,用不同浓度ox-LDL（6.25、12.5、25、50、100和150 mg/L）处理24 h后,形态学染色观察细胞凋亡,流式细胞仪检测细胞凋亡及细胞内活性氧（reactive oxygen species,ROS）水平,MTT法检测细胞活性,Western blot和RT-PCR分别检测PEDF蛋白和mRNA表达变化。结果显示,ox-LDL显著促进HUVECs凋亡、降低细胞活性、增加细胞内ROS含量,呈浓度依赖性地降低PEDF的蛋白和转录表达水平,与对照组相比,ox-LDL浓度达50 mg/L时,PEDF蛋白表达量显著降低（P〈0.05）,而ox-LDL浓度在25 mg/L时PEDF的mRNA表达水平已明显降低（P〈0.05）。以上结果表明,ox-LDL诱导PEDF表达降低,其机制可能与促进内皮细胞ROS生成有关。

英文摘要：

Pigment epithelium-derived factor （PEDF） is a multifunctional protein with anti-inflammatory, antioxidant and antithrom- botic properties and plays a protective role against atherosclerosis （AS）. The purpose of the present study is to explore the effects of oxidized low density lipoprotein （ox-LDL） on the expression of PEDF in cultured human umbilical vein endothelial cells （HUVECs）. HUVECs were cultured and incubated with ox-LDL at different concentrations （6.25, 12.5, 25, 50, 100 and 150 mg/L） for 24 h. Apoptosis of endothelial cells were assayed by morphological staining and flow cytometry. The intracellular reactive oxygen species （ROS） levels were measured by flow cytometry. Cell viability was assayed by MTT assay. PEDF protein and mRNA expressions in HUVECs were analyzed by Western blot and quantitative real-time PCR, respectively. The results showed that ox-LDL significantly induced apoptosis, reduced cell viability, increased intracellular ROS levels and decreased the PEDF expression in HUVECs in a concentration-dependent manner. Ox-LDL at 50 mg/L obviously decreased the PEDF protein expression compared with control group （P 〈 0.05）, whereas 25 mg/L ox-LDL already markedly reduced the PEDF mRNA expression （P 〈 0.05）. In conclusion, the results suggest that ox-LDL down-regulates the PEDF expression through an increased ox-LDL-induced intracellular production of ROS.