PAR SIGNALING AND PROTECTIVE PATHWAYS IN INFLAMMATION AND SEPSIS

凝血级联的内在信号方面已成为全身性炎症和败血症的主要贡献者和调节剂。我们的实验揭示了树突状细胞（dc）上一个意想不到的凝血酶蛋白酶激活受体（PAR） 1信号通路，该信号通路是导致败血症致死的系统性炎症反应综合征加重的原因。凝血酶激活的PAR1独特地与S1P受体3 （S1P3）偶联，促进dc依赖性炎症，诱导内皮功能障碍和血管渗漏。矛盾的是，内源性或治疗性给予活化蛋白C （aPC）的PAR1信号具有脓毒症保护作用。我们的数据表明，aPC的治疗作用既针对dc依赖性炎症，也针对血管渗漏，排除了“PAR1悖论”可以简单地归结为细胞类型特异性信号传导效应。我们提出验证PAR1与S1P受体亚型和调节共受体的偶联是在体内观察到的PAR激活的蛋白酶信号特异性的关键决定因素的总体假设。未来两年的实验将通过关注PAR1信号在dc和内皮细胞中的作用来推进这些概念。目的1是确定凝血酶和aPC信号在严重脓毒症中调节先天免疫功能的特定靶细胞群。这些实验促进了我们对固有免疫细胞受凝血级联内在信号控制的认识，并为测试DCs促炎PAR1-S1P3信号通路的药理调节新概念奠定了基础。在Aim 2中，我们使用血管内凝血剂平衡的遗传和药理学扰动来进一步表征PAR1在败血症中作为屏障破坏和屏障保护受体的双重作用。这些实验扩大了我们对PAR1信号的共受体如何促进血管屏障功能调节的认识，并为进一步测试改善炎症性疾病和败血症血管功能障碍的新治疗策略奠定了基础。

The intrinsic signaling aspects of the coagulation cascade have emerged as major contributors and regulators of systemic inflammation and sepsis. Our experiments uncovered an unexpected thrombin-protease activated receptor (PAR) 1 signaling pathway on dendritic cells (DCs) that is responsible for exacerbated systemic inflammatory response syndromes leading to sepsis lethality. Thrombin-activated PAR1 uniquely couples to sphingosine 1 phosphate (S1P) receptor 3 (S1P3) to promote DC-dependent inflammation and to induce endothelial dysfunction and vascular leakage. Paradoxically, PAR1 signaling by endogenous or therapeutically administered activated protein C (aPC) is sepsis protective. Our data indicate that therapeutic action of aPC targets both DC-dependent inflammation and vascular leakage, excluding that the “PAR1 paradox” can simply be reduced to cell type specific signaling effects. We propose to test the overall hypothesis that coupling of PAR1 to S1P receptor subtypes and regulatory co-receptors are the key determinants for the observed protease signaling specificity of PAR activation in vivo. The experiments in the upcoming two years will advance these concepts by focusing on the role of PAR1 signaling in DCs and endothelial cells. Aim 1 is to define the specific cell populations that are the target for thrombin and aPC signaling to regulate innate immune function in severe sepsis. These experiments advance our understanding of the innate immune cells that are controlled by the intrinsic signaling of the coagulation cascade and lay the foundation for testing new concepts of pharmacological modulation of the pro-inflammatory PAR1-S1P3 signaling pathway of DCs. In Aim 2, we use genetic and pharmacological perturbations of the intravascular coagulant balance to further characterize the dual role of PAR1 as a barrier disruptive and barrier protective receptor in sepsis. These experiments expand our knowledge of how co-receptors of PAR1 signaling contribute to the regulation of vascular barrier function and set the stage for further testing of new therapeutic strategies that improve vascular dysfunction in inflammatory disorders and sepsis. 3.