Claytor R Brannon, Michelson Alan D, Li Jian-Ming, Frelinger A L, Rohrer Michael J, Garnette Charles S C, Barnard Marc R, Krueger Lori A, Furman Mark I
Department of Surgery, Division of Vascular Surgery, and Center for Platelet Function Studies, University of Massachusetts Medical School, Worcester, Mass. 01655, USA.
J Vasc Surg. 2003 Feb;37(2):440-5. doi: 10.1067/mva.2003.129.
Platelet-endothelial cell adhesion is an important pathologic response to vessel injury or inflammation. On binding to its endothelial or platelet G protein-linked seven-transmembrane domain receptor, protease-activated receptor-1 (PAR1), thrombin releases a 41-amino acid peptide (TR(1-41)). We examined the effect of TR(1-41) on platelet activation and on platelet-endothelial cell adhesion.
A monolayer of confluent human saphenous vein endothelial cells was incubated with washed human platelets. Platelets were stimulated with either TR(1-41), TR(21-41), scrambled TR(1-41), adenosine diphosphate (ADP)-epinephrine (EPI), thrombin, or thrombin receptor activating peptide (TRAP). Platelet activation was identified with flow cytometry. The magnitude of platelet-endothelial cell adhesion was determined with a laser scanning cytometer that scanned the monolayer of endothelial cells and identified fluorescently bound platelets.
Maximal thrombin stimulation (0.1 U/mL) induced a threefold increase in platelets bound to endothelial cells compared with buffer alone. Stimulation with TR(1-41) (20 mmol/L) tripled the number of platelets bound to endothelial cells compared with thrombin. Scrambled sequence of TR(1-41) (20 mmol/L) and TR(21-41) (20 mmol/L), neither of which induces platelet activation, had minimal effect on platelet adhesion. Both TRAP (20 mmol/L) and ADP-EPI (20 mmol/L) induced less platelet-endothelial cell adhesion than did thrombin. TR(1-41)-induced platelet-endothelial cell adhesion was partially blocked by glycoprotein (GP)IIb-IIIa-specific monoclonal antibody, 10E5 (10 mg/mL).
TR(1-41), the cleaved peptide of PAR1, is a more potent stimulant of platelet-endothelial cell adhesion than is thrombin, TRAP, or ADP-EPI, and this adhesion is at least in part mediated by the platelet GPIIb-IIIa receptor.
血小板与内皮细胞的黏附是对血管损伤或炎症的一种重要病理反应。凝血酶与其内皮或血小板G蛋白偶联的七跨膜结构域受体蛋白酶激活受体-1（PAR1）结合后，会释放出一个41个氨基酸的肽段（TR(1 - 41)）。我们研究了TR(1 - 41)对血小板活化及血小板与内皮细胞黏附的影响。
将汇合的人隐静脉内皮细胞单层与洗涤后的人血小板共同孵育。用TR(1 - 41)、TR(21 - 41)、乱序TR(1 - 41)、二磷酸腺苷（ADP）-肾上腺素（EPI）、凝血酶或凝血酶受体激活肽（TRAP）刺激血小板。通过流式细胞术鉴定血小板活化情况。用激光扫描细胞仪测定血小板与内皮细胞的黏附程度，该仪器扫描内皮细胞单层并识别荧光标记的黏附血小板。
与单独使用缓冲液相比，最大凝血酶刺激（0.1 U/mL）使黏附于内皮细胞的血小板增加了两倍。与凝血酶相比，用TR(1 - 41)（20 mmol/L）刺激使黏附于内皮细胞的血小板数量增加了两倍。TR(1 - 41)的乱序序列（20 mmol/L）和TR(21 - 41)（20 mmol/L）均不诱导血小板活化，对血小板黏附的影响极小。TRAP（20 mmol/L）和ADP - EPI（20 mmol/L）诱导的血小板与内皮细胞黏附均少于凝血酶。TR(1 - 41)诱导的血小板与内皮细胞黏附被糖蛋白（GP）IIb - IIIa特异性单克隆抗体10E5（10 mg/mL）部分阻断。
PAR1的裂解肽TR(1 - 41)比凝血酶、TRAP或ADP - EPI更能有效刺激血小板与内皮细胞的黏附，且这种黏附至少部分由血小板GPIIb - IIIa受体介导。
