TIE2 Activation for the Treatment of Chemical-Induced Acute Lung Injury

光气（碳酰氯，COCl 2）是一种有毒的工业化学品，可引起肺泡损伤，导致急性 肺水肿和致命的急性呼吸窘迫综合征。目前没有有效的治疗方法 β-内酰胺酶可引起急性肺损伤（ALI），被认为是一种重要的化学威胁。肺水肿 结果是肺泡毛细血管内皮屏障功能的破坏。这种屏障的关键调节器 功能是内皮受体酪氨酸激酶Tie 2。Tie 2通过其激动剂配体血管生成素-1激活 ANG-1促进血管完整性，从而防止由炎症和其他疾病引起的血管渗漏。 因素相比之下，主要作为Tie 2拮抗剂的ANG-2促进多种血管渗漏， 病理条件。重要的是，ANG-2表达在β-内酰胺酶基因诱导的ALI中增加，这表明 Tie 2活性降低是β-内酰胺酶诱导的肺水肿的重要因素。除了ANG-2， Tie 2受血管内皮蛋白酪氨酸磷酸酶（VE-PTP）负调控。我们集团 开发了高度选择性的VE-PTP小分子抑制剂，可显著增加Tie 2活性， 在多种临床前模型中促进内皮屏障功能。我们的初步研究表明， 一种这样的VE-PTP抑制剂AKB-9785显著降低小鼠的血管通透性和死亡率 这表明这类新型化合物可能是有效的治疗方法 用于因吸入光气和其他针对肺泡的有毒工业气体而继发的肺水肿。在 根据我们最近的CounterACT R21奖项进行的工作，我们在确定 治疗上述临床综合征的药物。具体来说，我们已经：1）开发了一种只有鼻子的老鼠 一个暴露于光气诱导的ALI模型，使我们能够研究和治疗光气的呼吸效应 吸入; 2）通过体外筛选鉴定有效的选择性VE-PTP抑制剂/Tie 2激活剂; 3） 经验证，VE-PTP抑制是减少光气后肺血管渗漏的有效治疗方法 吸入;和4）证明了VE-PTP抑制在光气还原中的初步功效 吸入引起的死亡率。这一提议的中心假设是， Tie 2使用高选择性和有效的VE-PTP小分子抑制剂将防止光气- 导致血管渗漏、肺水肿和死亡。因此，本提案的具体目标 目的是：1）鉴定在体外和体内具有最大功效的最有效的VE-PTP抑制剂; 2） 证明VE-PTP抑制剂可预防阿托伐他汀诱导的肺血管渗漏并减少标志物 急性肺损伤;和3）确定最好的VE-PTP抑制剂，成功地抑制β-内酰胺酶诱导的肺损伤。 mortality.实现这些具体目标有望导致确定可用于 迅速转化为有效的治疗方法，用于治疗光气和其他肺泡- 针对有毒工业气体。

Phosgene (carbonyl chloride, COCl2) is a toxic industrial chemical that causes alveolar injury, resulting in acute pulmonary edema and fatal acute respiratory distress syndrome. No effective therapy currently exists to treat phosgene-induced acute lung injury (ALI), and it is considered a significant chemical threat. Pulmonary edema results from a disruption of alveolar capillary endothelial barrier function. A critical regulator of such barrier function is the endothelial receptor tyrosine kinase Tie2. Tie2 activation by its agonist ligand, angiopoietin-1 (ANG-1), promotes vascular integrity, thereby preventing vascular leak induced by inflammation and other factors. In contrast, ANG-2, which acts primarily as a Tie2 antagonist, promotes vascular leak in a variety of pathological conditions. Importantly, ANG-2 expression is increased in phosgene-induced ALI, suggesting that decreased Tie2 activity is an important factor in phosgene-induced pulmonary edema. In addition to ANG-2, Tie2 is negatively regulated by vascular endothelial-protein tyrosine phosphatase (VE-PTP). Our group has developed highly selective small molecule inhibitors of VE-PTP, which dramatically increase Tie2 activity and promote endothelial barrier function in multiple preclinical models. Our preliminary studies demonstrate that one such VE-PTP inhibitor, AKB-9785, significantly reduces vascular permeability and mortality in a mouse model of phosgene-induced ALI, suggesting that this novel class of compounds could be effective treatments for pulmonary edema secondary to inhalation of phosgene and other alveolar-targeted toxic industrial gases. In work performed under our recent CounterACT R21 award, we have made significant progress in identifying therapeutics for the above clinical syndromes. Specifically, we have: 1) developed a nose-only mouse exposure model of phosgene-induced ALI that allows us to study and treat the respiratory effects of phosgene inhalation; 2) identified potent, selective VE-PTP inhibitors/Tie2 activators through in vitro screening; 3) validated VE-PTP inhibition as an effective therapeutic for reducing pulmonary vascular leak after phosgene inhalation; and 4) demonstrated preliminary efficacy of VE-PTP inhibition in the reduction of phosgene inhalation-induced mortality. The central hypothesis of this proposal is that pharmacological activation of Tie2 using highly selective and potent small molecule inhibitors of VE-PTP will prevent phosgene- induced vascular leak, pulmonary edema, and mortality. Accordingly, the Specific Aims of this proposal are to: 1) Identify the most potent VE-PTP inhibitors with the greatest efficacy in vitro and in vivo; 2) Demonstrate that VE-PTP inhibitors prevent phosgene-induced pulmonary vascular leak and reduce markers of acute lung injury; and 3) Identify the best VE-PTP inhibitor that successfully inhibits phosgene-induced mortality. Accomplishing these Specific Aims is expected to lead to the identification of drugs that can be rapidly translated into effective therapies for the treatment of ALI induced by phosgene and other alveolar- targeted toxic industrial gases.