SIGNALING MOLECULES IN ACUTE LUNG INJURY

炎症机制参与了炎症的启动、放大， 成人呼吸窘迫综合征的传播和解决 （ARDS）。 中性粒细胞在ARDS患者的肺部积聚， 释放颗粒酶和其他毒素，介导细胞损伤 肺泡-毛细血管膜的损伤， 活体实验动物。 类似的信号分子，如 白细胞介素和生物活性脂质，直接激活PMN 并诱导颗粒内容物的移动， 自由基和其他功能改变由内皮细胞表达 和其他细胞。 这些信号的身份 分子仍然是未知的，导致这种分子的机制 以一种失调的、有害的方式表达， 一种自我平衡的、保护性的方式，仍然不明确。 这方面的广泛目标 项目是表征不同的中性粒细胞信号分子， 类，定义调节其表达的机制，以及 确定失调的机制。 我们将在这里重点介绍 诱导中性粒细胞增殖的信号分子的表征 脱粒，因为这一事件似乎是特别重要的 在ARDS发病机制中的作用。 在初步的实验中，我们发现， 细胞因子IL-1和TNF α或与LPS一起合成信号分子 诱导PMN分泌乳铁蛋白，一种特殊的颗粒标记物， 弹性蛋白酶，初级颗粒蛋白酶，进入流体相。 最大 脱粒信号的产生与表面分离， 介导PMN粘附和迁移的分子的表达。 这些特征表明，脱粒因子不参与 中性粒细胞的生理性迁移。 这些特征表明， 脱粒因子不参与生理靶向事件。 此外，内皮细胞单层在孵育时被破坏， 与PMN在存在的脱粒活性，这表明， 由该因子诱导的弹性蛋白酶或其它PMN蛋白酶的释放 介导内皮损伤。 我们的假设是人类内皮细胞产生并释放一种 一种新的刺激PMN脱颗粒的信号分子。 PMN颗粒 蛋白酶放大肺泡毛细血管膜的损伤， 在ARDS中发生的血管破坏的关键介质。 失调 内皮细胞表达信号分子是一个基本的 急性肺损伤的病理生理机制 我们的具体目标是：1）纯化，表征，测序和克隆 新的脱粒因子。2)为了表征生物活性， 反颗粒化因子。3)为了表征合成和 分泌因子，并确定其与其他信号传导的关系 分子。 4)为了确定是否存在脱粒因子， 在急性、亚急性和急性期， ARDS的修复阶段。

Inflammatory mechanisms are involved in the initiation, amplification, propagation, and resolution of Adult Respiratory Distress Syndrome (ARDS). Neutrophils accumulate in the lungs of patients with ARDS, release granular enzymes and other toxins that mediate damage to cells of the alveolar-capillary membrane in vitro, and injure lungs of experimental animals in vivo. Similarly signaling molecules, such as interleukin and biologically-active lipids, that directly activate PMNs and induced mobilization of granular contents, generation of oxygen radicals, and other functional alterations are expressed by endothelium and other cells in ARDS. The identities of many of these signaling molecules remain unknown, and the mechanisms that cause such molecules to become expressed in a dysregulated, injurious fashion, as opposed to a homeostatic, protective fashion, remain undefined. Broad goals of this project are to characterize neutrophil signaling molecules of different classes, define the mechanisms that regulate their expression, and determine mechanisms of dysregulation. We will focus here on characterization of a signaling molecule that induces neutrophil degranulation, because this event appears to be of particular importance in the pathogenesis of ARDS. In preliminary experiments, we found that endothelial cells treated with the cytokines IL-1 and TNFa or with LPS, synthesize a signaling molecule that induces PMN to secrete lactoferrin, a specific granule marker, and elastase, primary granule protease, into the fluid phase. Maximal generation of the degranulating signal is dissociated from surface expression of molecules that mediate adhesion and transmigration of PMN. These features suggest that the degranulating factor is not involved in physiologic transmigration of PMN. These features suggest that the degranulating factor is not involved in physiologic targeting events. Furthermore, endothelial cell monolayers are disrupted when incubated with PMN in the presence of the degranulating activity, suggesting that release of elastase or other PMN proteases induced by this factor mediates endothelial injury. Our hypotheses are that human endothelial cells generate and release a novel signaling molecule that stimulates PMN degranulation. PMN granular proteases amplify injury to the alveolar capillary membrane and may be key mediators of vascular destruction that occurs in ARDS. Dysregulated expression of signaling molecules by endothelial cells is a fundamental pathophysiologic mechanism in acute lung injury. Our specific aims are: 1) To purify, characterize, sequence, and clone the new degranulating factor. 2) To characterize the biologic activities of the degranulating factor. 3) To characterize the synthesis and secretion of the factor and define its relationship to other signaling molecules. 4) To determine if the degranulating factor is found in the blood or lung tissue of patients during the acute, subacute, and reparative phases of ARDS.