Koga Takuro, Kwan Paul, Zubik Ligia, Ameho Clement, Smith Donald, Meydani Mohsen
Vascular Biology Laboratory, Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University, 711 Washington Street, Boston, MA 02111, USA.
Atherosclerosis. 2004 Oct;176(2):265-72. doi: 10.1016/j.atherosclerosis.2004.05.034.
Suppression of cell adhesion molecule expression and macrophage accumulation by the endothelium is believed to play an important role in preventing the development of atherosclerosis. Earlier, we have shown that in vitro supplementation of human aortic endothelial cells with Vitamin E dose-dependently reduced expression of adhesion molecules and monocyte adhesion. Here, we report the in vivo down-regulation of endothelial cell adhesion molecules expression and macrophage accumulation in the aortas of hypercholesterolemic rabbits supplemented with Vitamin E. To this end, New Zealand White rabbits were fed a semi-purified diet containing 30 (control) or 1000 IU/kg Vitamin E. After 4 weeks, both groups' diets were switched to an atherogenic diet (0.3% cholesterol, 9% hydrogenated coconut oil, and 1% corn oil) containing the respective levels of Vitamin E and fed for 2, 4, and 6 weeks. Vitamin E supplemented rabbits had significantly higher levels of Vitamin E in their plasma and aortas. Frozen aorta sections were fixed and stained by an avidin-biotin complex method using Rb2/3 and Rb1/9 monoclonal antibodies against rabbit ICAM-1 and VCAM-1, respectively, and with RAM-11 for macrophage and von Willebrand factor for endothelial cells, followed by staining with secondary antibodies and counterstaining and evaluation under the microscope. At 6 weeks on atherogenic diet treatment, a trend (P = 0.08) toward a lower score of ICAM-1 expression by endothelial cells was observed in the aorta of Vitamin E treated rabbits compared to the control. However, a decrease in the score of VCAM-1 expression by endothelial cells in Vitamin E treated rabbits did not reach to a statistical significance. At 4 and 6 weeks on atherogenic diet, Vitamin E supplementation also significantly (P = 0.003) inhibited the accumulation of macrophages in the aorta. These results support the concept that down-regulation of adhesion molecule expression and suppression of monocyte/macrophage activation by Vitamin E in vivo is one of the potential mechanisms by which Vitamin E may suppress the development of aortic lesions in a rabbit model of atherosclerosis.
内皮细胞对细胞粘附分子表达的抑制及巨噬细胞的聚集被认为在预防动脉粥样硬化发展中起重要作用。此前，我们已表明，在体外用人主动脉内皮细胞补充维生素E可剂量依赖性地降低粘附分子的表达及单核细胞粘附。在此，我们报告在补充维生素E的高胆固醇血症兔主动脉中，内皮细胞粘附分子表达及巨噬细胞聚集在体内的下调情况。为此，给新西兰白兔喂食含30（对照）或1000 IU/kg维生素E的半纯化饮食。4周后，两组的饮食都换成含相应水平维生素E的致动脉粥样硬化饮食（0.3%胆固醇、9%氢化椰子油和1%玉米油），并喂养2、4和6周。补充维生素E的兔子血浆和主动脉中的维生素E水平显著更高。将冷冻的主动脉切片固定，并用抗兔ICAM-1的Rb2/3和抗兔VCAM-1的Rb1/9单克隆抗体，以及用于巨噬细胞的RAM-11和用于内皮细胞的血管性血友病因子，通过抗生物素蛋白-生物素复合物法进行染色，随后用二抗染色、复染并在显微镜下评估。在致动脉粥样硬化饮食治疗6周时，与对照组相比，在维生素E处理的兔子主动脉中观察到内皮细胞ICAM-1表达得分有降低趋势（P = 0.08）。然而，维生素E处理的兔子内皮细胞VCAM-1表达得分的降低未达到统计学显著性。在致动脉粥样硬化饮食4周和6周时，补充维生素E也显著（P = 0.003）抑制了主动脉中巨噬细胞的聚集。这些结果支持这样的观点，即维生素E在体内下调粘附分子表达及抑制单核细胞/巨噬细胞活化是维生素E可能在兔动脉粥样硬化模型中抑制主动脉病变发展的潜在机制之一。
