血小板激活因子介导过氧化氢引起的白细胞-内皮细胞粘附

Platelet-activating Factor Mediates Hydrogen Peroxide Induced Endothelial-leukocyte Adhesion

用体外培养的牛肺动脉内皮细胞单层(EC)研究过氧化氢(H_2O_2)对内皮细胞-中性粒细胞(EC-PMN)粘附的影响及其机理。不同浓度H_2O_2(10^(-3),10^(-2),10^(-1) mol/L)促进EC侬赖性的PMN粘附,10^(-2)mol/L作用最强,使PMN粘附率增加1.3倍。血小板激活因子(PAF)受体拮抗剂SRI 63-441预处理PMN对H_2O_2引起的EC-PMN粘附没有影响,预处理EC可显著降低粘附率。磷脂酶A_2抑制剂对溴苯酰基溴、钙调蛋白抑制剂氯丙嗪和钙离子螯合剂EGTA预处理EC都能显著降低H_2O_2引起的EC-PMN粘附。结果提示H_2O_2激活EC,细胞外Ca^(2+)内流,同时可能有细胞贮存Ca^(2+)释放,并与鲺调蛋白结合,激活磷脂酶A_2,起动PAF合成代谢,促进EC-PMN粘附。

The effects of hydrogen peroxide (H2O2) on endothelial-polymorphonuclear cells (EC-PMN) adhesion and their mechanisms wsre studied in cultured bovine pulmonary artery endothelial monolayers in vitro. H2O2 at various concentrations (10-1, 10-2, 10-3mol/L respectively) stimulated EC dependent PMN adhesion, of which l02mol/L H2O2 was the most potent one, increasing adhesion to 2.3 times that of the control. Pretreatment of PMNs with SRI 63-441, a platelet-activating factor (PAF) receptor antagonist, had no effect on H2O2 induced EC-PMN adhesion. Pretreatment of ECs with SRI 63-441 before H2O2 exposure significantly decreased PMN adherence to ECs. Pretreatment of ECs with phospholipase A2 inhibitor p-bromophenacyl-bromide or cahnodulin antagonist chlorpromazine and aildum ion chelate EGTA obviously decreased H2O2 induced increment of EC-PMN adhesion. These results suggest that H2O2 may activate ECs, causing the inflow of extracellular calcium or the release of calcium from intracellular deposits. Increased intracellular Ca2+ may bind with calmodulin to activate phospholipase A2 thus initiating PAF synthesis and promoting EC-PMN adhesion.