Microparticulate Caspase-1 mediated Lung Injury.

 描述(申请人提供)：急性肺损伤(ALI)及其更严重的形式，急性呼吸窘迫综合征(ARDS)，是与严重脓毒症相关的最常见的临床综合征，是美国发病率和死亡率的重要原因，死亡率为40%。虽然对ALI/ARDS的细胞损伤和死亡的发病机制有很多了解，但我们的认识存在一些空白，因此目前还没有有效的药物治疗方法。在这种情况下，被称为半胱氨酸天冬氨酸酶的酶对于完成凋亡程序是必不可少的。吞噬细胞，特别是单核/巨噬细胞，被认为是肺部炎症和免疫反应的主要成分，并富含caspase，尤其是caspase-1。最近发现，caspase-1的功能超越了对IL-1和IL-18的处理和激活，还包括对核因子-kB的调节和诱导细胞凋亡。本项目旨在扩展我们最近的观察，即微粒子caspase-1可以从单核吞噬细胞中释放出来，对靶细胞产生远距离的影响。本项目旨在研究一种新的假说，将包裹在循环小泡中的凋亡酶caspase-1与肺细胞损伤和细胞凋亡联系起来。中心假说是靶向特定微粒中释放的单核/巨噬细胞caspase-1可促进肺细胞凋亡，增强肺损伤。该项目为研究ARDS患者内皮细胞损伤和血管功能障碍的机制提供了一个亟需的努力和框架，以加深我们对细胞损伤的分子机制的理解，并为阻止ALI/ARDS患者的细胞损伤提供新的治疗机会。因此，为了确定这一新途径的特异性，我们提出了以下具体目标：1)发现单核细胞来源的胞外caspase-1损伤肺血管内皮细胞的详细机制；2)表征危重患者血清中循环caspase-1的存在形式；3)确定靶细胞如何摄取胞外caspase-1。这个项目提供了一个机会来研究caspase-1在单核细胞/内皮细胞相互作用和细胞凋亡的复杂生物学中的作用。这项工作的成功完成将揭示微粒子和caspase-1介导的炎症体信号转导的关键成分，增强我们对细胞损伤的分子机制的理解，并为阻止脓毒症患者ALI/ARDS的肺破坏提供新的治疗机会。

 DESCRIPTION (provided by applicant): Acute lung injury (ALI) and its more severe form, the acute respiratory distress syndrome (ARDS), are the most prevalent clinical syndromes associated with severe sepsis and are important causes of morbidity and mortality in United States with a mortality rate of 40%. Although much is known about the pathogenesis of cell injury and death in ALI/ARDS, there are several gaps in our knowledge; as a result of which there is currently no effective pharmacologic therapy. In this context, enzymes known as caspases are essential for completion of the apoptotic program. Phagocytes, in particular monocyte/macrophages, are recognized as major components of inflammatory and immunologic reactions in the lung and are rich reservoirs of caspases, especially caspase-1. The function of caspase-1 has recently been recognized to extend beyond the processing and activation of IL-1ß and IL-18 to include regulation of NF-kB and induction of apoptosis. The present project seeks to expand upon our recent observation that microparticulate caspase-1 can be released from mononuclear phagocytes to have distant effects on target cells. The present project seeks to investigate a novel hypothesis that links apoptotic enzyme, caspase-1, encapsulated in circulatory vesicles, to lung cell injury and apoptosis. The central hypothesis is that monocyte/macrophage caspase-1 released in target specific microparticles can promote lung cell apoptosis, enhancing lung injury. This project provides a much needed effort and framework to study the poorly understood mechanism of endothelial cell injury and vascular dysfunction in ARDS patients, to enhance our understanding of the molecular mechanisms underlying the cell injury and provide new therapeutic opportunities to halt the cell injury in ALI/ARDS patients. Therefore, to determine the specifics of this novel pathway, we propose the following specific aims: 1) To discover the detailed mechanisms by which monocyte derived extracellular caspase-1 injures lung vascular endothelial cells, 2) To characterize the forms of circulating caspase-1 present in the serum of critically ill patients and 3) To determine how extracellular caspase-1 is taken up by target cells. This project provides an opportunity to examine the role of caspase-1 in the complex biology of monocyte/endothelial cell interactions and apoptosis. Successful completion of this work will uncover critical components of microparticles and caspase-1 mediated inflammasome signaling, enhance our understanding of the molecular mechanisms underlying the cell injury and provide new therapeutic opportunities to halt the lung destruction in septic patients with ALI/ARDS.