Beauchamp P, Richard V, Tamion F, Lallemand F, Lebreton J P, Vaudry H, Daveau M, Thuillez C
IFRMP 23, INSERM E9920, VACOMED, the Department of Pharmacology, Rouen University Medical School, INSERM U78, INSERM U413, Rouen, France.
Circulation. 1999 Aug 3;100(5):541-6. doi: 10.1161/01.cir.100.5.541.
Preconditioning with brief periods of ischemia protects the coronary endothelium against acute and chronic reperfusion injury, but the mechanisms of this endothelial protection remain unknown. We hypothesized that preconditioning protects endothelial cells through a decreased production of endothelial adhesion molecules such as intercellular adhesion molecule-1 (ICAM-1), leading to a lesser adhesion of neutrophils to the endothelium.
Cultured rat aortic endothelial cells were subjected to 6-hour anoxia followed by various durations of reoxygenation. Preconditioning was induced by 1-hour anoxia and 1-hour reoxygenation. ICAM-1 gene expression was measured by polymerase chain reaction, and the percentage of cells expressing ICAM-1 was assessed by confocal laser fluorescence microscopy. Anoxia/reoxygenation increased expression of ICAM-1, with a peak occurring after 6 hours of reoxygenation for mRNA and 9 hours for protein. Preconditioning prevented the increase in ICAM-1. Similar reductions were observed with the free radical scavenger N-2 mercaptopropionyl glycine (MPG). The inhibitory effect of preconditioning on ICAM-1 expression was abolished by an inhibitor of protein kinase C, an inhibitor of nitric oxide synthesis, and by MPG but was not affected by an adenosine receptor antagonist. Finally, both preconditioning and MPG partially prevented the increased adhesion of human neutrophils to reoxygenated endothelial cells.
Preconditioning prevented reoxygenation-induced, free radical-mediated expression of ICAM-1 by a mechanism involving activation of protein kinase C and production of nitric oxide and free radicals, and this is associated with a lesser adhesion of neutrophils to endothelial cells. Such prevention of neutrophil adhesion may contribute to the protective effect of preconditioning against reperfusion-induced endothelial injury.
短暂缺血预处理可保护冠状动脉内皮细胞免受急性和慢性再灌注损伤，但其内皮保护机制尚不清楚。我们推测预处理通过减少内皮黏附分子如细胞间黏附分子-1（ICAM-1）的产生来保护内皮细胞，从而减少中性粒细胞与内皮的黏附。
培养的大鼠主动脉内皮细胞先经历6小时缺氧，然后进行不同时长的复氧。预处理通过1小时缺氧和1小时复氧诱导。采用聚合酶链反应检测ICAM-1基因表达，并用共聚焦激光荧光显微镜评估表达ICAM-1的细胞百分比。缺氧/复氧增加了ICAM-1的表达，mRNA在复氧6小时后达到峰值，蛋白质在复氧9小时后达到峰值。预处理可防止ICAM-1的增加。自由基清除剂N-2-巯基丙酰甘氨酸（MPG）也观察到类似的降低。蛋白激酶C抑制剂、一氧化氮合成抑制剂和MPG可消除预处理对ICAM-1表达的抑制作用，但不受腺苷受体拮抗剂影响。最后，预处理和MPG均部分阻止了人中性粒细胞与复氧内皮细胞黏附的增加。
预处理通过涉及蛋白激酶C激活、一氧化氮和自由基产生的机制，防止了复氧诱导的、自由基介导的ICAM-1表达，这与中性粒细胞与内皮细胞的黏附减少有关。这种对中性粒细胞黏附的预防可能有助于预处理对再灌注诱导的内皮损伤的保护作用。
