High concentrations of active plasminogen activator inhibitor-1 in porcine coronary artery thrombi
High concentrations of active plasminogen activator inhibitor-1 in porcine coronary artery thrombi
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DOI：
10.1161/01.atv.16.10.1277
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发表时间：
1996-10-01
影响因子：
8.7
通讯作者：
Owen, WG
中科院分区：
文献类型：
--
作者：
Fay, WP;Murphy, JG;Owen, WG
在纤维蛋白凝块中加入外源性纤溶酶原激活物抑制物-1(PAI-1)可抑制体内的纤溶。然而，目前尚不清楚产生这种抗纤溶作用所必需的局部浓度的活性PAI-1是否可以通过内源性机制招募到急性动脉血栓中。我们检测了猪急性血管损伤后形成的冠状动脉血栓中PAI-1的活性和抗原。血栓(n=5)中PAI-1平均活性为36+/-5.1微克/毫升，是正常猪血浆浓度的2000倍。免疫活性分析和在血栓提取物中加入I-125-尿激活酶后形成了稳定的十二烷基硫酸钠复合体，证实了血栓中活性PAI-1的浓度显著升高。通过Western blotting和尿激酶抑制实验对PAI-1抗原的比较分析表明，大约三分之一的血栓相关PAI-1是活性的。冠状动脉血栓的组织学检查显示，血栓主要由致密的血小板聚集体和散布的纤维蛋白岛组成，这与心肌梗死和不稳定型心绞痛患者血栓的组织学形态非常相似。从外周血中制备的洗涤猪血小板含有足够的PAI-1抗原和活性，可以解释冠状动脉血栓中观察到的浓度。然而，人血小板PAI-1的比活性低于猪血小板PAI-1的比活性(分别为2%和50%)，人血小板在体外对纤溶的抑制程度低于猪血小板。这些结果表明，活性PAI-1在猪冠状动脉血栓中积聚的浓度明显高于血浆中的浓度，PAI-I可能是已知的富含血小板的血栓抵抗组织型纤溶酶原激活剂溶解的一个重要决定因素。这些研究还强调了在比较人类血栓形成的动物模型和急性冠状动脉血栓形成时，考虑蛋白质功能可能存在的物种差异的重要性。
Addition of exogenous plasminogen activator inhibitor-1 (PAI-1) to fibrin clots inhibits fibrinolysis in vivo. However, it is unknown whether the localized concentrations of active PAI-1 necessary to produce this antifibrinolytic effect can be recruited to acute arterial thrombi by endogenous mechanisms. We measured PAI-1 activity and antigen in porcine coronary artery thrombi that formed in response to acute vascular injury. Mean PAI-1 activity in thrombi (n=5) was 36+/-5.1 mu g/mL, which is >2000 times its concentration in normal porcine plasma. The presence of markedly elevated concentrations of active PAI-1 in thrombi was confirmed by an immunoactivity assay and by demonstrating formation of sodium dodecyl sulfate-stable complexes after addition of I-125-urokinase to thrombus extracts. Comparative analysis of PAI-1 antigen by Western blotting and urokinase inhibition assay suggested that approximately one third of thrombus-associated PAI-1 was active. Histological examination of coronary thrombi revealed that they consisted predominantly of dense aggregates of platelets with interspersed islands of fibrin, which closely resemble the histological appearance of thrombi in patients with myocardial infarction and unstable angina pectoris. Washed porcine platelets prepared from peripheral blood contained sufficient PAI-1 antigen and activity to account for the concentrations observed in coronary artery thrombi. However, the specific activity of human platelet PAI-1 was lower than that of porcine platelet PAI-1 (2% versus 50% active, respectively), and human platelets inhibited in vitro fibrinolysis to a lesser extent than did porcine platelets. These results indicate that active PAI-1 accumulates in porcine coronary artery thrombi in concentrations markedly higher than those present in plasma and that PAI-I may be an important determinant of the known resistance of platelet-rich thrombi to lysis by tissue-type plasminogen activator. These studies also underscore the importance of considering possible species differences in protein function when comparing animal models of thrombosis to acute coronary thrombosis in humans.