Critical role of chymase in the regulation of inflammation and survival in sepsis

描述（由申请人提供）：败血症是一种极其普遍且通常致命的疾病，可由宿主对细菌感染的免疫反应失调引起。作为抵御感染的第一道防线，炎症是健康免疫反应的必要组成部分，但过多的炎症会引发一系列病理生理过程，而受影响的患者无法充分补偿，从而导致败血症的诊断。据估计，每年有75万例败血症病例，死亡率在20-50%之间。重要的是，最近的研究表明，脓毒症的发病率正在上升，并预计将继续随着人口老龄化。因此，了解调节细菌感染免疫的机制和途径是必要的。基于我们对脓毒症相关机制的初步调查，我们假设乳糜酶，一种肥大细胞特异性蛋白酶，限制了对细菌的炎症反应的强度，降低了严重脓毒症的风险。具体来说，我们的数据表明，酶能够限制促炎介质如肿瘤坏死因子（TNF）的净负面影响。-通过蛋白水解裂解限制TNF？脓毒症盲肠结扎和穿刺（CLP）模型的体内水平和受体激活。此外，我们的初步研究表明，我们可以使用蛋白质组学方法来鉴定新的乳糜酶调节介质，作为我们阐明乳糜酶在脓毒症期间改变免疫反应和调节炎症中的作用的一部分。因此，我们提出了一项研究计划，旨在剖析乳糜酶在败血症中保护宿主的机制，并确定限制这种保护作用的因素。在Aim 1中，我们将定义使乳糜酶调节炎症和促进脓毒症生存的因素。具体来说，我们将确定在败血症中诱导肥大细胞活化和乳糜酶释放的机制。在Aim 2中，我们将评估乳糜酶介导的TNF？在败血症中可归因于直接蛋白水解。在Aim 3中，我们将确定与糖化酶生理相关的蛋白水解底物，以确定该蛋白酶在败血症中的整体作用。总之，这些研究有可能提供定义脓毒性炎症反应的“蛋白质特征”，并可用于更有效地诊断和治疗这种复杂疾病。我们相信这些研究将为未来的项目奠定基础，这些项目旨在了解引发炎症反应失调并导致严重败血症中多器官功能障碍和死亡的级联事件。

DESCRIPTION (provided by applicant): Sepsis is an extremely prevalent and often fatal disorder that can arise from dysregulation in a host's immune response to bacterial infection. Being the first line of defense against infection, inflammation is a necessary part of a healthy immune response, but too much inflammation can trigger a cascade of pathophysiological processes for which the affected patient cannot adequately compensate, resulting in a diagnosis of sepsis. There are an estimated 750,000 cases of sepsis per year, with mortality rates ranging from 20-50%. Importantly, recent studies indicate that the incidence of sepsis is rising and is projected to continue as the population ages. Understanding the mechanisms and pathways regulating immunity against bacterial infection, then, is imperative. Based on our preliminary investigations into such mechanisms as they pertain to sepsis, we hypothesize that chymase, a mast cell-specific protease, limits the magnitude of the inflammatory response against bacteria and reduces the risks of severe sepsis. Specifically, our data indicate that chymase is able to limit the net negative effects of pro-inflammatory mediators like tumor necrosis factor (TNF)?-through proteolytic cleavage limiting TNF? levels and receptor activation in vivo-in the cecal ligation and puncture (CLP) model of sepsis. Moreover, our preliminary studies indicate that we can use proteomics approaches to identify novel chymase-regulated mediators as part of our effort to elucidate the roles of chymase in altering the immune response and regulating inflammation during sepsis. Accordingly, we propose a research plan aimed at dissecting the mechanisms by which chymase protects its host in sepsis and at defining the factors that can limit this protective effect. In Aim 1, we will define the factors that enable chymase to regulate inflammation and promote survival in sepsis. Specifically, we will determine the mechanisms that induce mast cell activation and chymase release in sepsis. In Aim 2, we will assess the extent to which chymase-mediated down-regulation of TNF? in sepsis can be attributed to direct proteolysis. In Aim 3, we will identify physiologically relevant proteolytic substrates for chymase to establish the overall role of this protease in sepsis. Together, these studies have the potential to provide "protein signatures" that define the septic inflammatory response and can be used for more effective diagnosis and treatment of this complex disorder. We are confident that these studies will lay the groundwork for future projects aimed at understanding the cascade of events that initiate a dysregulated inflammatory response and lead to multiple organ dysfunction and death in severe sepsis. PUBLIC HEALTH RELEVANCE: The proposed studies will provide essential information on the mechanisms by which mast cell chymase regulates the host inflammatory response against bacterial infection. This information will lay the groundwork for future projects aimed at understanding the cascade of events that lead to sepsis and may facilitate the design of new strategies to diagnose and/or prevent sepsis.