Regulation of Inflammation by the Fibrinolytic System

止血和免疫是高度相关的系统。止血、血栓形成和紊乱的调节失调 输精血管内凝血(DIC)是创伤、无菌患者常见的严重并发症 组织损伤、全身炎症和败血症。这项研究项目的重点是一种新的途径，通过它 纤溶活性的主要血管内激活剂--组织型纤溶酶原激活剂(TPA)控制着先天的血压升高。 社交化和炎症。低密度脂蛋白受体相关蛋白-1(LRP1)是一种内吞和细胞信号受体 对于tPA。当LRP1在小鼠髓系细胞中有条件地缺失时，对脂多糖的炎症反应- 糖类/内毒素(LPS)的作用大大加剧。在LRP1缺陷的巨噬细胞中，NFκB被激活并 促炎症细胞因子的表达显著增加。MicroRNA-155的表达也增加， 它可以维持炎症，就像蛇酶纤溶抑制物、纤溶酶原激活剂的表达一样 抑制物-1(PAI-1)和PAI-2，它们有助于血栓前状态。在表达LRP1的巨噬细胞中， 与LRP1结合的不同配体对巨噬细胞的表型和基因表达有相反的影响 我们假设反映了巨噬细胞共受体的配体特异性募集的现象，包括N- 甲基-D-天冬氨酸受体。TPA与LRP1的结合具有抗炎作用。酶失活tPA(EI-tPA) 阻断内毒素对野生型小鼠的毒性。TPA的抗炎活性代表了一种新的和 FDA批准的药物的意外活性。这项拨款申请的主要目的是澄清 组织型纤溶酶原激活剂在炎症中的活性及其抗血栓形成的新途径 组织损伤和败血症。提出了三个具体目标。在具体目标1中，我们应用了系统生物学 巨噬细胞EI-tPA与LRP1结合激活抗炎信号通路的研究进展 噬菌体。将特别注意识别辅助受体，即发挥功能的信号蛋白系统。 同时调节基因表达，以及SOCS1和SOCS3等基因产物，它们可能 确定tPA对炎症的影响是否持续。在具体目标2中，我们检验了假设 TPA通过检测两个可供选择的模型系统抑制对多种刺激的炎症反应 在小鼠中，脂磷壁酸攻击和被动的K/BxN血清转移性关节炎模型中，先天免疫。 免疫功能由Fc受体和补体因子激活。在具体目标3中，我们检验了Ei-Ei- 在创伤和脓毒症等情况下，TPA可能通过以下方式对抗血栓前状态的发展 控制巨噬细胞中的基因表达。在特定目标中提出的实验3侧重于平衡 纤溶酶原激活剂及其抑制物与促进纤溶酶原的细胞表面受体之间的关系 由tPA激活。总体而言，这个项目提供了一个机会来加深我们对 纤溶和控制炎症的细胞系统。正在研究的新途径可能会产生 慢性炎症和止血药物开发的新靶点。

Hemostasis and immunity are highly interrelated systems. Dysregulation of hemostasis, thrombosis, and dis- seminated intravascular coagulation (DIC) are serious complications observed in patients with trauma, sterile tissue injury, systemic inflammation, and sepsis. This research project focuses on a novel pathway by which the major intravascular activator of fibrinolysis, tissue-type Plasminogen Activator (tPA), controls innate im- munity and inflammation. LDL Receptor-related Protein-1 (LRP1) is an endocytic and cell-signaling receptor for tPA. When LRP1 is deleted conditionally in myeloid cells in mice, the inflammatory response to lipopoly- saccharide/endotoxin (LPS) is greatly exacerbated. In LRP1-deficient macrophages, NFκB is activated and expression of pro-inflammatory cytokines is robustly increased. microRNA-155 expression also is increased, which may sustain inflammation, as is expression of the Serpin fibrinolysis inhibitors, plasminogen activator inhibitor-1 (PAI-1) and PAI-2, which contribute to a pro-thrombotic state. In macrophages that express LRP1, different ligands that bind to LRP1 have opposite effects on macrophage phenotype and gene expression, a phenomenon that we hypothesize reflects ligand-specific recruitment of macrophage co-receptors, including N- methyl-D-aspartate Receptor. tPA-binding to LRP1 is anti-inflammatory. Enzymatically-inactive tPA (EI-tPA) blocks the toxicity of LPS in wild-type mice. The anti-inflammatory activity of tPA represents a novel and unanticipated activity of an FDA-approved drug. The major objective of this grant application is to elucidate the activity of tPA in inflammation and a novel pathway by which tPA may counteract development of thrombosis in tissue injury and sepsis. Three specific aims are proposed. In Specific Aim 1, we apply a systems biology approach to elucidate the anti-inflammatory signaling pathway activated by EI-tPA-binding to LRP1 in macro- phages. Specific attention will be dedicated to identifying co-receptors, systems of signaling proteins that func- tion concomitantly to regulate gene expression, and gene products such as SOCS1 and SOCS3, which may determine whether the effects of tPA on inflammation are sustained. In Specific Aim 2, we test the hypothesis that tPA suppresses inflammation in response to multiple stimuli by examining two alternative model systems in mice, lipoteichoic acid challenge and the passive K/BxN serum-transfer arthritis model, in which innate im- munity is activated by Fc receptors and complement factors. In Specific Aim 3, we test the hypothesis that EI- tPA may counteract development of pro-thrombotic states in conditions such as trauma and sepsis by controlling gene expression in macrophages. Proposed experiments in Specific Aim 3 focus on the balance between plasminogen activators and their inhibitors and on cell-surface receptors that promote plasminogen activation by tPA. Overall, this project offers an opportunity to further our understanding of crosstalk between fibrinolysis and cellular systems that control inflammation. The novel pathways under investigation may yield new targets for drug development in chronic inflammation and hemostasis.