Regulation of granulocyte-derived elastase-dependent fibrinolysis

根据以下观察，我们推测纤溶酶原激活物-纤溶酶依赖性纤溶系统与粒细胞源性弹性酶依赖性纤溶系统之间可能存在一种串扰：1、先天性纤溶酶原缺乏患者无血管内嗜血栓发作。这些患者血浆中粒细胞源性弹性蛋白酶水平比正常人高10-100倍。此外，输注纯化的纤溶酶原可使其水平降至正常范围。2、严重脓毒症合并弥散性血管内凝血患者纤溶酶原激活物-纤溶酶依赖性纤溶系统可能因纤溶酶原激活物抑制剂-1显著升高而关闭。采用针对人纤维蛋白的粒细胞源性弹性酶片段D种特异性单克隆抗体的ELISA系统，我们发现弹性酶纤维蛋白消化在这些患者中大多升高。为了支持这一假设，我们使用了合成弹性酶抑制剂的纤溶酶原缺陷小鼠（KO小鼠）。7周后，19%的KO小鼠由于微循环血管内血栓形成而发生直肠脱垂。出乎意料的是，给药弹性蛋白酶抑制剂保护KO小鼠免受直肠脱垂。此外，脂多糖负荷后肺内白细胞浸润量和纤维蛋白沉积量也因同时抑制弹性酶而减少。这些结果表明，两个系统之间的串扰更为复杂，需要更多地了解弹性蛋白酶在替代纤溶系统中的作用。

We have hypothesized that there might be a kind of cross-talk between plasminogen activator-plasmin dependent fibrinolytic system and granulocyte-derived elastase dependent one, according to the following observations : 1, congenital plasminogen-deficient patients have no intravascular thrombophilic episodes. The granulocyte-derived elastase level of these patients in plasma is 10-100 times higher than that of the normal. Moreover, infusion of purified plasminogen decreases the level to a normal range. 2, plasminogen activator-plasmin dependent fibrinolytic system is supposed to be shutdown by remarkable increase of plasminogen activator inhibitor-1 in patient with disseminated intravascular coagulation associated with severe sepsis. Using ELISA system employing a monoclonal antibody specific to the granulocyte-derived elastase-fragment D species of human fibrin, we found that the elastase fibrin-digests were mostly elevated in these patients.To support this hypothesis, we used plasminogen-deficient mice (KO mice) with synthetic elastase inhibitor. After the age of 7 weeks, 19% of KO mice develop rectal prolapse due to intravascular thrombosis in microcirculation. Unexpectedly, administration of elastase inhibitor protected KO mice from rectal prolapse. In addition, the amount of leukocyte infiltration and a fibrin deposit in the lung after lipopolysacharride loading were also decreased by concomitant elastase inhibition. These results suggest a cross-talk between two systems is more complicated and much more needs to be learned about the role of elastase in relation to alternative fibrinolytic system.