凝血酶引发血小板α-颗粒脱颗粒，导致活性纤溶酶原激活物抑制剂-1（PAI-1）释放。
Thrombin Provokes Degranulation of Platelet α-Granules Leading to the Release of Active Plasminogen Activator Inhibitor-1 (PAI-1).
机构信息
Department of Surgery, University of Colorado, Aurora, Colorado.
Department of Surgery, Denver Health Medical Center, Denver, Colorado.
出版信息
Shock. 2018 Dec;50(6):671-676. doi: 10.1097/SHK.0000000000001089.
BACKGROUND
The balance of fibrinolytic mediators is crucial to the survival of the critically ill patient, with tissue plasminogen activator (t-PA) and plasminogen activator inhibitor-1 (PAI-1) playing significant roles. While elevated levels of PAI-1 are associated with increased morbidity and mortality, the source of this PAI-1 remains elusive. Platelets contain 90% of circulating plasma PAI-1, however, their ability to release active PAI-1 is controversial. We hypothesize platelets contain active PAI-1 in α-granules capable of immediate degranulation when exposed to high concentrations of thrombin.
METHODS
In vitro apheresis platelets were stimulated with thrombin (1 IU/mL, 5 IU/mL) followed by the collection of supernatant (5-120 min). Supernatant and lysate PAI-1 was measured by ELISA. The experiment was repeated in the presence of t-PA followed by measurement of t-PA:PAI-1 complex measurement by ELISA. Finally, healthy whole blood underwent dilution with control and thrombin-treated platelet lysate followed by thrombelastography (TEG) in a t-PA-stimulated TEG.
RESULTS
Thrombin provoked immediate near-complete degranulation of PAI-1 from α-granules (median 5m 5 IU/mL thrombin 125.1 ng/mL, 1 IU/mL thrombin 114.9 ng/mL, control 9.9 ng/mL). The released PAI-1 rapidly complexed with t-PA, with a 4-fold increase in complex formation in the thrombin-treated supernatant. Conversely, PAI-1 in the control lysate demonstrated a 6-fold increase in complex formation compared with thrombin lysate. Last, control platelet lysate inhibited t-PA-induced fibrinolysis by TEG (median LY30 control 15m 7.9%), while thrombin-treated platelet lysates, after PAI-1 degranulation, were unable to affect the fibrinolysis profile (median LY30 5 IU/mL 28.5%, 1 IU/mL 12.4%).
CONCLUSION
Thrombin provokes rapid α-degranulation of active PAI-1, capable of complexing with t-PA and neutralizing t-PA-induced fibrinolysis by TEG.
背景
纤维蛋白溶解介质的平衡对危重病患者的生存至关重要，组织型纤溶酶原激活物（t-PA）和纤溶酶原激活物抑制剂-1（PAI-1）起着重要作用。虽然 PAI-1 水平升高与发病率和死亡率增加有关，但这种 PAI-1 的来源仍不清楚。血小板含有循环血浆 PAI-1 的 90%，然而，它们释放有活性的 PAI-1 的能力存在争议。我们假设血小板在α-颗粒中含有有活性的 PAI-1，当暴露于高浓度的凝血酶时，这些 PAI-1 能够立即脱颗粒。
方法
用凝血酶（1IU/mL，5IU/mL）刺激体外分离的血小板，然后收集上清液（5-120 分钟）。通过 ELISA 测量上清液和裂解物中的 PAI-1。在 t-PA 存在的情况下重复该实验，然后通过 ELISA 测量 t-PA:PAI-1 复合物的测量。最后，用对照和凝血酶处理的血小板裂解物稀释健康全血，然后在 t-PA 刺激的血栓弹力图（TEG）中进行 TEG。
结果
凝血酶迅速引发了 PAI-1 从α-颗粒的几乎完全脱颗粒（中位数 5m 5IU/mL 凝血酶 125.1ng/mL，1IU/mL 凝血酶 114.9ng/mL，对照 9.9ng/mL）。释放的 PAI-1 迅速与 t-PA 形成复合物，在凝血酶处理的上清液中复合物形成增加了 4 倍。相反，对照裂解物中的 PAI-1 与凝血酶裂解物相比，复合物形成增加了 6 倍。最后，对照血小板裂解物通过 TEG 抑制 t-PA 诱导的纤维蛋白溶解（中位数 LY30 对照 15m 7.9%），而在 PAI-1 脱颗粒后，凝血酶处理的血小板裂解物无法影响纤维蛋白溶解谱（中位数 LY30 5IU/mL 28.5%，1IU/mL 12.4%）。
结论
凝血酶迅速引发有活性的 PAI-1 的α-脱颗粒，能够与 t-PA 形成复合物，并通过 TEG 中和 t-PA 诱导的纤维蛋白溶解。
Zotero 插件