Introduction

Protease activated receptors 1 (PAR1) and 4 (PAR4) agonists are used to study platelet activation. Data on platelet activation are extrapolated across experimental settings. C1-inhibitor (C1INH) is a protease inhibitor present in plasma but not in isolated platelet suspensions. Here we show that C1INH affects platelet activation through PAR1 and PAR4 agonists.

Methods

Platelets were isolated from healthy donor whole blood and then labeled with anti-CD62P and PAC1 antibodies. The platelet suspensions were exposed to PAR1 agonists SFLLRN, TFLLR and TFLLRN; PAR4 agonists AYPGKF and GYPGQV; ADP and thrombin. Flow-cytometric measurements were performed in 5, 10 and 15 min after activation.

Results

0.25 mg/ml C1INH addition made platelets to faster expose CD62P and glycoprotein IIb/IIIa complex after activation with PAR1 agonists. Conversely, C1INH addition led to inhibition of platelet activation with PAR4 agonists and thrombin. Activation with ADP was not affected by C1INH.

Conclusions

Our results suggest that C1INH can modify platelet activation in the presence of synthetic PAR agonists used in platelet research. These observations may be relevant to the development of new methods to assess platelet function.

中文翻译：

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C1抑制剂对凝血酶受体激动剂对血小板活化的影响

介绍

蛋白酶激活受体 1 (PAR1) 和 4 (PAR4) 激动剂用于研究血小板活化。关于血小板活化的数据在实验设置中外推。C1 抑制剂 (C1INH) 是一种蛋白酶抑制剂，存在于血浆中，但不存在于分离的血小板悬浮液中。在这里，我们显示 C1INH 通过 PAR1 和 PAR4 激动剂影响血小板活化。

方法

从健康供体全血中分离血小板，然后用抗 CD62P 和 PAC1 抗体标记。血小板悬浮液暴露于 PAR1 激动剂 SFLLRN、TFLLR 和 TFLLRN；PAR4 激动剂 AYPGKF 和 GYPGQV；ADP 和凝血酶。在激活后 5、10 和 15 分钟进行流式细胞仪测量。

结果

添加 0.25 mg/ml C1INH 可使血小板在用 PAR1 激动剂激活后更快地暴露 CD62P 和糖蛋白 IIb/IIIa 复合物。相反，C1INH 添加导致 PAR4 激动剂和凝血酶抑制血小板活化。ADP 的激活不受 C1INH 的影响。

结论

我们的结果表明，在血小板研究中使用的合成 PAR 激动剂存在的情况下，C1INH 可以改变血小板活化。这些观察结果可能与开发评估血小板功能的新方法有关。