PAR SIGNALING AND PROTECTIVE PATHWAYS IN INFLAMMATION AND SEPSIS

凝血级联的内在信号方面已经成为全身性炎症和脓毒症的主要贡献者和调节剂。我们的实验发现了一个意想不到的凝血酶-蛋白酶激活受体（PAR）1信号通路的树突状细胞（DC），是负责加重全身炎症反应综合征，导致败血症致死。凝血酶激活的PAR 1独特地偶联至1磷酸鞘氨醇（S1 P）受体3（S1 P3）以促进DC依赖性炎症并诱导内皮功能障碍和血管渗漏。有趣的是，通过内源性或治疗性施用的活化蛋白C（aPC）的PAR 1信号传导是脓毒症保护性的。我们的数据表明aPC的治疗作用靶向DC依赖性炎症和血管渗漏，排除了“PAR 1悖论”可以简单地归结为细胞类型特异性信号传导效应。我们建议测试的总体假设，PAR 1耦合到S1 P受体亚型和调节辅助受体是观察到的蛋白酶信号传导特异性PAR激活在体内的关键决定因素。未来两年的实验将通过关注PAR 1信号在DC和内皮细胞中的作用来推进这些概念。目的1是确定作为凝血酶和aPC信号传导的靶点的特异性细胞群，以调节严重脓毒症中的先天免疫功能。这些实验推进了我们对先天免疫细胞的理解，这些先天免疫细胞由凝血级联的内在信号传导控制，并为测试DC的促炎PAR 1-S1 P3信号传导通路的药理学调节的新概念奠定了基础。在目标2中，我们利用血管内凝血平衡的遗传和药理学扰动来进一步表征PAR 1作为脓毒症中屏障破坏性和屏障保护性受体的双重作用。这些实验扩展了我们对PAR 1信号传导的共受体如何促进血管屏障功能调节的知识，并为进一步测试改善炎症性疾病和脓毒症中血管功能障碍的新治疗策略奠定了基础。 3.

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.