ROLE OF VEGF IN ATHEROGENESIS

免疫组织化学研究表明，人类早期动脉粥样硬化病变在增厚内膜的内皮下巨噬细胞丰富区域表现出强烈的血管内皮生长因子（VEGF）免疫反应性。在动脉粥样硬化斑块中，在脂质核心附近的泡沫细胞丰富区域或主要由平滑肌细胞组成的斑块新血管化的基底区域也观察到VEGF染色。高倍视野观察发现VEGF定位于细胞外间隙和巨噬细胞表面。这些观察结果提示氧化低密度脂蛋白（Ox-LDL）可能通过在巨噬细胞中诱导VEGF参与人动脉粥样硬化的发展。我们还证明了Ox-LDL在单核细胞系RAW 264细胞中以时间和浓度依赖的方式上调VEGF mRNA表达，并且Ox-LDL刺激细胞分泌VEGF蛋白。我们推测内皮下巨噬细胞丰富的血管内皮生长因子可能参与管腔内皮的维持和修复。为了验证我们的假设，我们研究了VEGF是否保护Ox-LDL对培养的牛主动脉内皮细胞（BAECs）的毒性。与VEGF预孵育的baec以预孵育时间和VEGF浓度依赖的方式阻止Ox-LDL毒性。与VEGF孵育的baec细胞内谷胱甘肽（GSH）以时间依赖性的方式增加。VEGF与GSH合成抑制剂l -丁硫氨酸亚砜胺联合添加可逆转GSH水平和VEGF对ox - ldl诱导的细胞毒性的保护作用。胎盘生长因子与VEGF Fit-1受体结合而不与KDR/Flk-1结合，不能阻止Ox-LDL毒性，对细胞内GSH水平无影响。抗KDR/Flk-1抗体完全阻断VEGF的这些活性。这些结果表明，VEGF通过KDR/Flk-1受体通过细胞内gsh依赖机制阻止ox - ldl诱导的内皮细胞损伤。少

Immunohistochemical studies showed that human early atherosclerotic lesions exhibited intensive vascular endothelial growth factor (VEGF) immunoreactivity in subendothelial macrophage-rich regions of thickened intima. In atherosclerotic plaques, VEGF staining was also observed in foam cell-rich regions adjacent to lipid core or neovascularized basal regions of plaque consisting predominantly of smooth muscle cells. High powered field observation revealed that VEGF was localized in extracellular space as well as macrophage cell surface. These observations suggest the possible involvement of oxidized loe density lipoprtein (Ox-LDL) in the development of human atherosclerosis through VEGF induction in macrophages. We also demonstrated that Ox-LDL upregulated VEGF mRNA expression in RAW 264 cells, monocytic cell line, in a time and concentration dependent manner, and that Ox-LDL stimulated the VEGF protein secretion from the cells.We hypothesized that VEGF in subendothelial macrophage-rich … More regions adjacent to endothelial cells at the luminal surface may participate in the maintenance and repair of the lumen endothelium. To test our hypothesis we examined whether VEGF protects the toxicity of Ox-LDL to cultured endothelial cells derived from bovine aorta (BAECs). BAECs preincubation with VEGF prevented Ox-LDL toxicity in a preincubation time- and VEGF concentration-dependent manner. Incubation of BAECs with VEGF increased intracellular glutathione (GSH) in a time-dependent manner. Combined addition of VEGF and L-buthionine sulfoximine, a GSH synthesis inhibitor, reversed GSH level and the protective effect of VEGF on Ox-LDL-induced cytotoxicity. Placenta growth factor, which ligates to VEGF Fit-1 receptor but not KDR/Flk-1, failed to prevent Ox-LDL toxicity and had no effect on intracellular GSH level. Anti- KDR/Flk-1 antibody completely blocked these activities of VEGF.These results suggest that VEGF prevents Ox-LDL-induced endothelial cell damage via intracellular GSH-dependent mechanism through KDR/Flk-1 receptor. Less