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。在恢复期早期，它会导致出血、血栓形成和多器官功能障碍综合症；在恢复期后期，它会促进病理组织修复和动态平衡，从而阻止恢复日常生活活动。严重创伤相关死亡和残疾与凝血和炎症(全身炎症反应综合征(SIRS))的病理激活程度直接相关，提示减轻TIC和/或SIRS可减少严重创伤引起的并发症。关于严重创伤后TIC和SIRS的分子煽动者，有一个关键的知识缺口。我们的初步数据支持一种变革性的假说，即纤溶酶的不适当早期激活是启动TIC和SIRS的关键事件，纤溶酶是组织修复和稳态所必需的主要蛋白酶，这也会导致纤溶酶活性的长期丧失，从而扰乱组织修复和稳态。前提：在孤立的创伤后，纤溶酶原的激活受到严格的调控，并仅限于伤口部位。然而，在严重创伤后，纤溶酶被系统激活(纤溶功能亢进)，随后纤溶酶活性长期缺乏(纤溶功能低下)，这两者都与不良预后有关。我们的中心假设是：(I)严重创伤后早期纤溶亢进是TIC和SIRS的主要促进剂，(Ii)早期纤溶亢进通过耗尽纤溶酶原而导致纤溶低下，(Iii)获得性纤溶酶原缺乏是病理组织动态平衡和修复的驱动因素。方法与方法：采用小鼠烧伤作为严重创伤的典型模型，目的1确定早期纤溶亢进是否加速TIC和SIRS，目的2确定早期纤溶亢进是否导致晚期持续性纤溶低下。纤溶酶活性将被药物抑制/增强，并使用新的分子工具进行测量。TIC和SIRS将通过已建立的生物标记物、血小板功能和器官特异性NF-κB定量的系列分析来评估，作为多器官功能障碍综合征的替代指标。纤溶系统将通过量化其单独的成分、酶抑制物复合体、纤维蛋白降解产物和活性分析来进行评估。接下来，在目标3中，我们将结合小鼠烧伤模型和股骨骨折和骨骼肌损伤模型来评估晚期纤溶低下是否会导致骨相关的病理改变，特别是骨折愈合受损、肌肉异位骨化和创伤诱发的骨质疏松症。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骼并发症，以及骨骼病理过程在多大程度上是由纤维蛋白或纤维蛋白介导的炎症引起的。综上所述，如果这些发现属实，这些发现将支持1)在早期康复期间抑制纤溶酶原激活，以部分防止TIC和SIRS，以及2)在晚期康复期间复苏纤溶酶原，或促进纤溶的替代方法，以保护骨骼健康。

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.