van Aalst John A, Burmeister William, Fox Paul L, Graham Linda M
Department of Surgery, Case Western Reserve University, Cleveland, OH, USA.
J Vasc Surg. 2004 Jan;39(1):229-37. doi: 10.1016/s0741-5214(03)01038-3.
Endothelial cell (EC) migration is essential for healing areas of arterial injury and angioplasty sites. Iron or copper-oxidized low-density lipoprotein (oxLDL(Cu)) inhibits EC migration in vitro, but the effect of physiologically relevant monocyte/macrophage-oxidized LDL (oxLDL(cell)) is unknown. We postulated that oxLDL(cell) would inhibit EC migration and that this inhibition would be reversed by antioxidants.
The effect of oxLDL(Cu) and oxLDL(cell) on EC migration was studied by using a razor scrape assay, and migration was assessed after 24 hours. In addition, ECs were incubated with various antioxidants, including butylated hydroxytoluene (BHT), probucol, or alpha-tocopherol, for 1 hour prior to initiation of the scrape assay and application of oxLDL.
Both oxLDL(Cu) and oxLDL(cell) inhibited migration. The antioxidants did not alter the antimigratory activity of oxLDL(Cu), but alpha-tocopherol preserved EC migration in the presence of oxLDL(cell). The lack of effect of BHT or probucol suggested that the effect of alpha-tocopherol resided not in its antioxidant activity but in its membrane-stabilizing properties. To test this theory, the effect of oxLDL and alpha-tocopherol on relative cell membrane fluidity was assessed by fluorescence recovery after photobleaching. Both oxLDL(Cu) and oxLDL(cell) increased relative membrane fluidity. Preincubation with alpha-tocopherol inhibited the increase in membrane fluidity of ECs incubated in oxLDL(cell) but not in oxLDL(Cu).
These studies show that alpha-tocopherol preserves EC migration in oxLDL(cell) and hastens restoration of the endothelial monolayer after injury by inhibiting changes in membrane integrity caused by oxLDL.
Recent studies find that vitamin E is not efficacious in the secondary prevention of cardiovascular events, perhaps because vitamin E does not efficiently block oxidation pathways known to be operative in atherosclerotic arteries. "Non-antioxidant" properties of vitamin E, however, could be important in the primary prevention of atherosclerosis and its complications. Our in vitro studies show that alpha-tocopherol can preserve endothelial migration in the presence of cell-oxidized LDL. This effect might improve the healing of endothelial injuries at sites of arterial repair or angioplasties, especially in lipid-laden arterial walls.
内皮细胞（EC）迁移对于动脉损伤区域和血管成形术部位的愈合至关重要。铁或铜氧化的低密度脂蛋白（oxLDL（Cu））在体外抑制EC迁移，但生理相关的单核细胞/巨噬细胞氧化的低密度脂蛋白（oxLDL（细胞））的作用尚不清楚。我们推测oxLDL（细胞）会抑制EC迁移，并且这种抑制作用会被抗氧化剂逆转。
使用剃须刮擦试验研究oxLDL（Cu）和oxLDL（细胞）对EC迁移的影响，并在24小时后评估迁移情况。此外，在开始刮擦试验和应用oxLDL之前，将EC与各种抗氧化剂（包括丁基化羟基甲苯（BHT）、普罗布考或α-生育酚）孵育1小时。
oxLDL（Cu）和oxLDL（细胞）均抑制迁移。抗氧化剂未改变oxLDL（Cu）的抗迁移活性，但α-生育酚在oxLDL（细胞）存在的情况下保留了EC迁移。BHT或普罗布考缺乏作用表明α-生育酚的作用不在于其抗氧化活性，而在于其膜稳定特性。为了验证这一理论，通过光漂白后的荧光恢复评估oxLDL和α-生育酚对相对细胞膜流动性的影响。oxLDL（Cu）和oxLDL（细胞）均增加了相对膜流动性。用α-生育酚预孵育可抑制在oxLDL（细胞）中孵育的EC的膜流动性增加，但不能抑制oxLDL（Cu）中的增加。
这些研究表明，α-生育酚在oxLDL（细胞）中保留EC迁移，并通过抑制oxLDL引起的膜完整性变化来加速损伤后内皮单层的恢复。
最近的研究发现维生素E在心血管事件的二级预防中无效，可能是因为维生素E不能有效地阻断已知在动脉粥样硬化动脉中起作用的氧化途径。然而，维生素E的“非抗氧化”特性在动脉粥样硬化及其并发症的一级预防中可能很重要。我们的体外研究表明，α-生育酚在细胞氧化的低密度脂蛋白存在的情况下可以保留内皮迁移。这种作用可能会改善动脉修复或血管成形术部位内皮损伤的愈合，特别是在富含脂质的动脉壁中。
