Tie2 Activation for the Treatment of Chemical-Induced Acute Lung Injury

说明(申请人提供)：光气是一种常见的有毒工业化学品，用于制造塑料和工业材料。暴露在光气中会引起主要针对肺泡的急性肺损伤(ALI)，导致急性肺水肿和致命的急性呼吸窘迫综合征。在这方面，它类似于其他针对肺泡的药剂，如氯苦和全氟异丁烯。目前还没有有效的疗法来治疗光气性ALI，它被认为是一个重大的化学威胁风险。血管生成素(Ang)-1/Tie2信号通路是炎症、血管内皮生长因子(又称血管通透因子)、5-羟色胺和组胺等多种刺激诱导的血管完整性和防止血管渗漏的最有效的介质之一，提示该信号通路非特异性地抑制血管通透性。Ang-1/Tie2信号转导受天然产生的拮抗配体Ang-2的负调控。大量证据表明，在脓毒症等多种病理条件下，Ang-2的表达上调在促进肺血管渗漏中起关键作用，抑制Ang-2或激活Ang-1/Tie2可以防止肺血管通透性，降低死亡率。最近，Ang-2在光气性ALI中的表达增加，表明Angiopoietin/Tie2通路是治疗化学性肺损伤的潜在靶点。除Ang-2外，Tie2还受到血管内皮细胞蛋白酪氨酸磷酸酶(VE-PTP)的负调控。我们小组的初步研究表明，用高选择性小分子化合物抑制VE-PTP可显著激活Tie2并增强内皮屏障功能。在肺血管渗漏导致高发生率休克和死亡的小鼠模型中，给予VE-PTP的小分子抑制剂完全阻断这些不良影响。基于这些结果，我们假设，使用高选择性和有效的VE-PTP小分子抑制剂激活Tie2将防止光气诱导的血管渗漏、肺水肿和死亡率。为了验证这一假说，这项建议的具体目的是：1)建立和表征光气诱导的急性肺损伤的小鼠模型；2)在体外找出最有效的VE-PTP抑制剂；以及3)确定VE-PTP抑制剂在预防光气诱导的小鼠肺血管渗漏、肺水肿、缺氧和死亡方面的有效性。完成这些目标将导致确定潜在的治疗性小分子，这些小分子可用于随后的药理学/毒理学测试和开发，作为吸入光气和类似有毒工业化学品造成的急性肺损伤的治疗方法。

DESCRIPTION (provided by applicant): Phosgene is a common toxic industrial chemical used in the manufacture of plastics and industrial materials. Exposure to phosgene gas causes acute lung injury (ALI) that primarily targets alveoli, resulting in acute pulmonary edema and fatal acute respiratory distress syndrome. In this respect, it is similar to other agents that target alveoli such as chloropicrin and perfluoroisobutylene. No effective therapies currently exist to treat phosgene-induced ALI, and it is considered a significant chemical threat risk. The Angiopoietin (Ang)-1/Tie2 signaling pathway is one of the most potent mediators of vascular integrity and prevention of vascular leak induced by a variety of stimuli, including inflammation, vascular endothelial growth factor (a.k.a., vascular permeability factor), serotonin, and histamine, suggesting that this pathway non-specifically inhibits vascular permeability. Ang-1/Tie2 signaling is negatively regulated by the naturally occurring antagonistic ligand, Ang-2. Substantial evidence now demonstrates that upregulation of Ang-2 plays a key role in promoting pulmonary vascular leak in a variety of pathological conditions, such as sepsis, and inhibition of Ang-2 or activation of Ang-1/Tie2 can prevent pulmonary vascular permeability and reduce mortality in sepsis models. Recently, Ang- 2 expression has been shown to be increased in phosgene-induced ALI, highlighting the Angiopoietin/Tie2 pathway as a potential therapeutic target in chemical-induced lung injury. In addition to Ang-2, Tie2 is negatively regulated by vascular endothelial protein tyrosine phosphatase (VE-PTP). Preliminary studies from our group demonstrate that inhibition of VE-PTP with highly selective small molecule compounds results in dramatic Tie2 activation and enhanced endothelial barrier function. In a mouse model of pulmonary vascular leak that causes a high incidence of shock and death, administration of a small molecule inhibitor of VE-PTP completely blocks these adverse effects. Based on these results, we hypothesize that activation of Tie2 using highly selective and potent small molecule inhibitors of VE-PTP will prevent phosgene-induced vascular leakage, pulmonary edema, and mortality. To test this hypothesis, the Specific Aims of this proposal are to: 1) Develop and characterize a mouse model of phosgene-induced acute lung injury; 2) Identify the most potent VE-PTP inhibitors with the greatest efficacy in vitro; and 3) Determine the efficacy of VE-PTP inhibitors in preventing phosgene-induced pulmonary vascular leak, pulmonary edema, hypoxia, and mortality in a mouse model. Completion of these Aims will lead to the identification of potentially therapeutic small molecules that can be advanced to subsequent pharmacology/toxicology testing and development as treatments for acute lung injury resulting from the inhalation of phosgene and similar toxic industrial chemicals.