Severe Trauma Provokes Pathologic Continuum of Plasmin Activation

项目概述：严重创伤是导致死亡和残疾的重要原因。在康复初期，它会引起出血、血栓形成和多器官功能障碍综合征;在康复后期，它会促使病理组织修复和体内平衡，从而阻止恢复日常生活活动。严重创伤相关的死亡和残疾与凝血（创伤诱导的凝血病（TIC））和炎症（全身炎症反应综合征（SIRS））的病理激活的激活程度直接相关，表明减轻TIC和/或SIRS将减少严重创伤引起的并发症。关于严重创伤后TIC和SIRS的分子引发剂存在关键的知识缺口。我们的初步数据支持一个变革性的假设，即纤溶酶的不适当的早期激活，纤溶酶是组织修复和体内平衡所必需的纤溶系统的主要蛋白酶，是引发TIC和SIRS的关键事件，也导致纤溶酶活性的长期丧失，破坏组织修复和体内平衡。预防措施：在孤立创伤后，纤溶酶原激活受到严格调节并局限于伤口部位。然而，在严重创伤后，纤溶酶被全身激活（纤维蛋白溶解亢进），随后是纤溶酶活性的长期缺乏（纤维蛋白溶解减退），这两者都与不良结局相关。我们的中心假设是：（i）严重创伤后的早期纤溶亢进是TIC和SIRS的主要促进因素，（ii）早期纤溶亢进通过耗尽纤溶酶原导致纤溶功能减退，以及（iii）获得性纤溶酶原缺乏是病理组织稳态和修复的驱动因素。方法和途径：采用小鼠烧伤作为严重创伤的代表性模型，我们将在目的1中确定早期纤溶亢进是否加速TIC和SIRS，在目的2中确定早期纤溶亢进是否导致晚期持续纤溶减退。纤溶酶活性将被抑制/增强，并使用新的分子工具进行测量。将通过对已建立的生物标志物、血小板功能和器官特异性NF-κB定量的系列分析评估TIC和SIRS，作为多器官功能障碍综合征的替代指标。将通过定量其单个元素、蛋白酶抑制剂复合物、纤维蛋白降解产物和活性测定来评估纤溶系统。接下来，在目标3中，我们将联合收割机将鼠烧伤模型与股骨骨折和骨骼肌损伤模型相结合，以评估晚期低纤维蛋白溶解是否引起骨相关的病理学;特别是骨折愈合受损、肌肉异位骨化和创伤诱导的骨质疏松症。在分子水平上，我们将确定恢复纤溶酶活性是否可以预防这些骨并发症，以及骨病理过程在多大程度上是由于纤维蛋白或纤维蛋白介导的炎症。总之，如果属实，这些发现将支持1）在早期恢复期抑制纤溶酶原活化，以部分预防TIC和SIRS，和2）在晚期恢复期复苏纤溶酶原，或促进纤维蛋白溶解的替代方法，以保持骨骼健康。

Project Summary: Severe trauma is a significant cause of death and disability. Early in convalescence, it causes bleeding, thrombosis and multi-organ dysfunction syndrome; later in convalescence, it instigates pathologic tissue repair and homeostasis, which prevents return to activities of daily living. Severe trauma related death and disability is directly correlated with the degree of activation of pathologic activation of coagulation (trauma- induce coagulopathy (TIC)) and inflammation (systemic inflammatory response syndrome (SIRS)) suggesting that mitigating TIC and/or SIRS would reduce complications caused by severe trauma. There is a key knowledge gap regarding the molecular instigators of TIC and SIRS following severe trauma. Our preliminary data support a transformative hypothesis that implicates inappropriate early activation of plasmin, the principle protease of the fibrinolytic system essential for tissue repair and homeostasis, as a key event that initiates TIC and SIRS, that also results in a prolonged loss of plasmin activity that disrupts tissue repair and homeostasis. Premise: Following an isolated trauma, plasminogen activation is tightly regulated and restricted to the wound site. However, following a severe trauma, plasmin is systemically activated (hyperfibrinolysis) followed by a prolonged deficit of plasmin activity (hypofibrinolysis), both of which are associated with poor outcomes. Our central hypothesis is that (i) early hyperfibrinolysis following severe trauma is a primary accelerant of TIC and SIRS, (ii) early hyperfibrinolysis causes hypofibrinolysis by exhausting plasminogen, and that (iii) the acquired plasminogen deficiency is a driver of pathologic tissue homeostasis and repair. Methods & Approach: Employing a murine burn injury as a representative model of severe trauma, we will determine in Aim 1 whether early hyperfibrinolysis accelerates TIC and SIRS and in Aim 2 whether early hyperfibrinolysis causes late sustained hypofibrinolysis. Plasmin activity will be pharmacologically inhibited/enhanced and measured using novel molecular tools. TIC and SIRS will be assessed with serial analysis of established biomarkers, platelet function, and organ specific NF-κB quantification as a surrogate measure of multiorgan dysfunction syndrome. The fibrinolytic system will be assessed by quantifying its individual elements, protease-inhibitor complexes, fibrin degradation products, and activity assays. Next, in Aim 3 we will combine the murine burn model with a femur fracture and skeletal muscle injury model to assess whether late hypofibrinolysis causes bone-related pathologies; specifically impaired fracture healing, heterotopic ossification in muscle, and trauma-induced osteoporosis. At the molecular level, we will determine if restoring plasmin activity prevents these bone complications and to what extent of the bone pathologic processes are due to fibrin, or fibrin mediated inflammation. Taken together, if true, these findings would provide support for 1) inhibition of plasminogen activation during the early convalescence to prevent, in part, TIC and SIRS and 2) resuscitation of plasminogen, or alternative means of promoting fibrinolysis, during late convalescence, to preserve bone health.