海参糖胺聚糖抑制血小板——内皮细胞粘附及调节血小板粘附分子表达

Effect of GAG on Platelet-Endothelial Cell Adhesion and Expression of Adhesion Molecules

目的：探讨玉足海参糖胺聚糖(GAG)对血小板与人脐静脉内皮细胞(HUVECs)粘附,及血小板粘附分子表达的调节作用。方法：应用流动小室模型检测GAG对活化血小板与HUVECs粘附反应的干预作用,通过激光共聚焦显微镜获取图像。采用流式细胞仪测定药物干预后活化血小板表面粘附分子GPⅡ_b/Ⅲ_a、GPⅠ_b的表达。结果：在高、低切变率作用下,不同浓度组GAG均可以抑制活化血小板与HUVECs的粘附反应,GAG5 mg/L组抑制作用最为明显,粘附率分别约为凝血酶组的35%和40%(P＜0.001,P＜0.001)。GAG可以显著抑制急性血栓形成小鼠血小板GPⅡ_b/Ⅲ_a的表达,虽然随着时间的延长GPⅡ_b/Ⅲ_a的表达呈上升趋势,但同对照组相比表达量仍低,有显著差异(P＜0.001)。同时GAG可以上调活化血小板GPⅠ_b的表达,表达量约为对照组的3倍(P＜0.001)。结论：GAG通过调节血小板粘附分子表达,抑制活化血小板与内皮细胞的粘附反应,因而可能是一种有效的抗血小板粘附剂。

Objective：The aim of this study was to assess the influence of holothurian glycosaminoglycan（GAG） on the adherence of thrombin-induced platelets to human umbilical vein endothelial cells（HUVECs） and the expression of adhesion molecules on activated platelets. Methods：Washed platelets and HUVECs were pre-induced by thrombin with or without different concentrations of GAG. The adhesion of activated platelets to HUVECs under different fluid shear stress conditions was measured in the flow chamber system and the photographs were obtained through laser scan confocal microscope（LSCM）. The expression of GPⅡb/Ⅲa ,GPIb on thrombin-induced platelets was tested by flow cytometry. Results：GAG （ l^10mg/L ） could inhibit the adhesion of activated platelets to HUVECs under both high and low fluid shear stress （ 1100s^-1 and 300s^-1 ,respectively ） . When GAG was at the concentration of 5mg/L, the inhibitive activity was most significant and the adhesion rates were about 35% and 40% of those in thrombin group respectively[（5. 24 ± 0. 26）% vs. （14. 85±0. 82） % and （6. 70 ±0. 29）% vs. （16.83 ± 0. 58）% ,respectively]. GAG could down-regulate the expression of platelet GPⅡb/Ⅲa on acute thromboembolism in mice. The inhibitory activity of GAG exhibited a weakening tendency forty minutes after the injection of thrombin, but the expression of GPⅡb/Ⅲa was still significantly lower in GAG group than in control group （ P〈0. 001 ） . About three- fold increase in the expression of GPL on thrombin-induced platelets was seen if co-cultured with GAG[（43.11 ±1.04） vs. （14.29±1.60）]. Conclusion：GAG might be an effective antiadhesive agent through modulating the expression of adhesion molecules on platelets and inhibiting the adhesion of platelets to endothelial cells.