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的疾病，通常是致命的，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，但太多的炎症会引发一连串的病理生理过程，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75万例脓毒症病例，死亡率从20%到50%不等。重要的是，最近的研究表明，脓毒症的发病率正在上升，并预计随着人口老龄化而持续下去。因此，了解调节免疫对抗细菌感染的机制和途径是当务之急。基于我们对这些与脓毒症相关的机制的初步研究，我们假设，肥大细胞特异性蛋白酶--糜酶可以限制针对细菌的炎症反应的幅度，并降低严重脓毒症的风险。具体地说，我们的数据表明，糜酶能够限制促炎介质的净负面影响，如肿瘤坏死因子？-通过蛋白水解性切割限制肿瘤坏死因子？体内水平和受体激活-盲肠结扎和穿孔(CLP)脓毒症模型。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识别新的凝乳酶调节的介体，作为我们努力阐明凝乳酶在脓毒症期间改变免疫反应和调节炎症的作用的一部分。因此，我们提出了一项研究计划，旨在剖析凝乳酶在脓毒症中保护宿主的机制，并确定限制这种保护作用的因素。在目标1中，我们将定义使凝乳酶能够调节炎症和促进脓毒症患者存活的因素。具体地说，我们将确定脓毒症中诱导肥大细胞激活和乳糜酶释放的机制。在目标2中，我们将评估糜酶介导的肿瘤坏死因子下调的程度？在脓毒症中可归因于直接的蛋白分解。在目标3中，我们将确定与凝乳酶相关的生理蛋白分解底物，以确定该酶在脓毒症中的总体作用。总之，这些研究有可能提供定义脓毒症炎症反应的“蛋白质信号”，并可用于这种复杂疾病的更有效的诊断和治疗。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失调炎症反应并导致严重脓毒症患者多器官功能障碍和死亡的一连串事件。 与公共卫生相关：拟议的研究将提供肥大细胞糜酶调节宿主对细菌感染的炎症反应的机制的基本信息。这些信息将为未来旨在了解导致脓毒症的一连串事件的项目奠定基础，并可能有助于设计新的战略来诊断和/或预防脓毒症。

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.