Zhi Kangkang, Li Maoquan, Bai Jun, Wu Yongfa, Zhou Sili, Zhang Xiaoping, Qu Lefeng
Department of Vascular and Endovascular Surgery, Changzheng Hospital, 415 Fengyang Road, Shanghai, 200003, China.
Department of Interventional Radiology, Tenth People's Hospital of Tongji University, 301 Yanchang Road, Shanghai, 200072, China.
Angiogenesis. 2016 Jul;19(3):311-24. doi: 10.1007/s10456-016-9504-y. Epub 2016 Mar 26.
Atherosclerosis is a disease resulting from impaired endothelial function, often caused by oxidant injury or inflammation. Endothelial progenitor cells (EPCs) play a critical role in repairing damaged endothelium and protecting against atherosclerosis. Quercitrin, a plant-derived flavonoid compound, displays antioxidant and anti-inflammatory activities. In this study, we showed that quercitrin treatment reduced the apoptosis of EPCs caused by oxidized low-density lipoprotein (ox-LDL) in a dose-dependent manner. Quercitrin improved tube formation, migration and adhesion of ox-LDL-treated EPCs. To determine the effect of quercitrin in vivo, EPCs treated with or without ox-LDL and quercitrin were locally injected into the ischemic hind limb muscle of nude mice. Those injected with EPCs treated with ox-LDL and quercitrin showed significantly increased local accumulation of EPCs, blood flow recovery and capillary density compared with the control and ox-LDL only groups. Furthermore, we showed that quercitrin enhanced autophagy and upregulated mitogen-activated protein kinase and ERK phosphorylation in a dose-dependent manner in vitro. Autophagy inhibitors, chloroquine and 3-methyladenine, abrogated quercitrin-enhanced autophagy caused by ox-LDL as evidenced by decreased numbers of branch points, migratory cells and adherent cells, and increased numbers of apoptotic cells. The ERK inhibitor PD98059 abrogated quercitrin-enhanced autophagy, as identified by decreased autophagosome formation and downregulated ERK phosphorylation. The inhibition of ERK did not affect the expression of Rac1, but enhanced phosphorylation of Akt. Quercitrin treatment also increased the expression of E-cadherin, and PD98059 abrogated the upregulation of E-cadherin induced by quercitrin. Our findings suggested that autophagy is a protective mechanism in EPCs exposed to oxidative damage. Quercitrin can promote autophagy through the activation of ERK and the ERK signaling pathway is therefore thought to play a pivotal role in mediating the protective effects on EPCs.
动脉粥样硬化是一种因内皮功能受损导致的疾病，常由氧化损伤或炎症引起。内皮祖细胞（EPCs）在修复受损内皮和预防动脉粥样硬化方面发挥着关键作用。槲皮苷是一种植物来源的黄酮类化合物，具有抗氧化和抗炎活性。在本研究中，我们发现槲皮苷处理以剂量依赖的方式减少了氧化型低密度脂蛋白（ox-LDL）诱导的EPCs凋亡。槲皮苷改善了ox-LDL处理的EPCs的管腔形成、迁移和黏附。为了确定槲皮苷在体内的作用，将经ox-LDL和槲皮苷处理或未处理的EPCs局部注射到裸鼠缺血后肢肌肉中。与对照组和仅ox-LDL组相比，注射经ox-LDL和槲皮苷处理的EPCs的小鼠局部EPCs积累显著增加，血流恢复和毛细血管密度增加。此外，我们发现槲皮苷在体外以剂量依赖的方式增强自噬并上调丝裂原活化蛋白激酶和ERK磷酸化。自噬抑制剂氯喹和3-甲基腺嘌呤消除了ox-LDL诱导的槲皮苷增强的自噬，表现为分支点、迁移细胞和黏附细胞数量减少，凋亡细胞数量增加。ERK抑制剂PD98059消除了槲皮苷增强的自噬，表现为自噬体形成减少和ERK磷酸化下调。ERK的抑制不影响Rac1的表达，但增强了Akt的磷酸化。槲皮苷处理还增加了E-钙黏蛋白的表达，而PD98059消除了槲皮苷诱导的E-钙黏蛋白上调。我们的研究结果表明，自噬是暴露于氧化损伤的EPCs中的一种保护机制。槲皮苷可通过激活ERK促进自噬，因此ERK信号通路被认为在介导对EPCs的保护作用中起关键作用。
