Inflammasome Activation Triggers Systemic Coagulation in Sepsis

摘要 感染性休克总是与全身凝血有关，导致血栓形成。脓毒症相关 器官功能障碍被归因于微血管血栓形成。脓毒症患者死亡率翻一番 合并弥漫性血管内凝血(DIC)。DIC甚至被认为是“死亡即将来临”的标志。 已有研究表明组织因子(TF)在脓毒症相关DIC中的重要作用。 然而，导致脓毒症时引发全身凝血的转铁蛋白释放的机制尚不清楚。 最近的体外研究表明，细菌成分(鞭毛蛋白，III型分泌物的杆状蛋白) 系统(T3SS)，或内毒素)通过激活诱导巨噬细胞程序性死亡(称为下垂) 炎症性小体的路径。我们发现静脉注射T3SS杆状蛋白大肠杆菌EprJ可以诱导 组织中外周血单核细胞和巨噬细胞的耗竭。重要的是，注射EprJ或内毒素， 分别诱导典型和非典型炎症体激活，诱导全身凝血 激活，表现为凝血酶原时间(PT)延长，这是由于凝血因子消耗增加所致。 血小板减少，血浆凝血酶-抗凝血酶复合体(TAT)水平升高，血浆水平降低 纤维蛋白原水平。因此，我们的发现将体外观察和体内观察联系起来 提示单核/巨噬细胞下垂是脓毒症患者DIC的触发因素。此应用程序的目标是 描述炎症小体激活和下睑下垂在脓毒症中触发DIC的潜在机制。 特定目标1将炎症小体激活和下垂确立为DIC的常见机制 由细菌感染引起的。工作假说是细菌和细菌成分来自不同的 菌株通过炎症体激活和下垂诱导DIC。我们将使用各种不同的组合 基因缺陷小鼠阐明炎性小体激活和上睑下垂在革兰氏阴性菌所致DIC中的作用 细菌。特异性目标2是确定巨噬细胞释放转铁蛋白的分子机制 炎性小体激活。我们还将使用髓系特异性Tf基因敲除小鼠和低Tf小鼠模型 目的：阐明细菌成分引起的DIC是否依赖于巨噬细胞释放Tf。 具体目标3将证明炎性小体激活在脓毒症相关凝血障碍中的作用。我们会 采用盲肠结扎穿刺术(CLP)脓毒症模型和细菌输注脓毒症模型。 炎性小体激活和下垂在凝血中的作用。建议的研究完成后， 说明全身凝血的分子机制是脓毒症。这样的发现将具有深远的意义 败血症的致命并发症DIC的新药靶点确定的分支。

Abstract Septic shock is invariably associated with systemic coagulation leading to thrombus formation. Sepsis-related organ dysfunction has been attributed to microvascular thrombosis. Mortality rate doubles in septic patients with disseminated intravascular coagulation (DIC). DIC is even considered as a sign that “death is coming”. Previous studies have demonstrated the important roles of tissue factor (TF) in sepsis-associated DIC. However, the mechanism leading to TF release, which triggers systemic coagulation in sepsis, is unknown. Recent in vitro studies revealed that bacterial components (flagellin, the rod protein of the type III secretion system (T3SS), or LPS) induce programmed cell death (called pyroptosis) of macrophages through activation of inflammasome pathways. We show that intravenous injection of a T3SS rod protein E. coli, EprJ, induced depletion of peripheral monocytes and macrophages in tissues. Importantly, injection of EprJ or LPS, which elicit canonical and noncanonical inflammasome activation, respectively, induced systemic coagulation activation, as evident by prolonged prothrombin time (PT) due to increased consumption of coagulation factors, thrombocytopenia, increased plasma levels of thrombin-antithrombin complex (TAT), and reduced plasma fibrinogen levels. Thus, our findings made connections between the in vitro and in vivo observations and suggested monocyte/macrophage pyroptosis as a trigger of DIC in sepsis. The goal of this application is to delineate the underlying mechanisms by which inflammasome activation and pyroptosis trigger DIC in sepsis. Specific Aim 1 will establish inflammasome activation and pyroptosis as a common mechanism for DIC induced by bacterial infection. The working hypothesis is that bacteria and bacterial components from different strains elicit DIC through Inflammasome activation and pyroptosis. We will use a combination of various deficient mice to elucidate the role of inflammasome activation and pyroptosis in DIC elicited by Gram-negative bacteria. Specific Aim 2 is to identify the molecular mechanism of TF release from macrophages following inflammasome activation. We will also use the myeloid-specific TF knockout mice and a low TF mouse model to elucidate whether DIC elicited by the bacterial components depends on release of TF from macrophages. Specific Aim 3 will demonstrate the role of inflammasome activation in sepsis-associated coagulopathy. We will use the cecal ligation and puncture (CLP) sepsis model and bacterial infusion sepsis model to investigate the role of inflammasome activation and pyroptosis in coagulation. Completion of the proposed studies will demonstrate the molecular mechanism of systemic coagulation is sepsis. Such findings would have profound ramifications for the identification of new drug targets for DIC, the deadly complication of sepsis.