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炎症和脓毒症的主要贡献者和调节者。我们的实验揭示了树突状细胞(DC)上一条意想不到的凝血酶-蛋白酶激活受体(PAR)1信号通路，该信号通路导致全身炎症反应综合征加剧，导致脓毒症致死。凝血酶激活的PAR1与鞘氨醇1磷酸(S1P)受体3(S1P3)特异性偶联，促进DC依赖的炎症反应，诱导内皮功能障碍和血管渗漏。矛盾的是，内源性或治疗性应用活化蛋白C(APC)的PAR1信号对脓毒症具有保护作用。我们的数据表明，APC的治疗作用针对DC依赖的炎症和血管渗漏，排除了“PAR1悖论”可以简单地归结为细胞类型特定的信号效应。我们建议检验PAR1与S1P受体亚型和调节共受体的偶联是体内观察到的PAR激活的蛋白水解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重点研究PAR1信号在DC和内皮细胞中的作用来推进这些概念。目的1是确定在严重脓毒症中凝血酶和APC信号调节先天免疫功能的特定细胞群。这些实验促进了我们对受凝血级联固有信号控制的先天免疫细胞的理解，并为测试DCs促炎症信号通路PAR1-S1P3的药理调节新概念奠定了基础。在目标2中，我们利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在脓毒症中作为屏障干扰性和屏障保护性受体的双重作用。这些实验扩大了我们对PAR1信号的共同受体如何有助于调节血管屏障功能的了解，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.