Therapeutic Targeting of PTPN13 in Idiopathic Pulmonary Fibrosis

 描述(由申请人提供)： 项目摘要特发性肺纤维化(IPF)是一种致命的纤维性肺部疾病，其损害了肺泡内的气体交换。确诊后的中位生存期约为3年，几乎没有有效的治疗方法。虽然IPF的具体原因尚不清楚，但吸入粉尘、香烟烟雾和有毒化学物质是已知的患上这种疾病的风险因素，这种疾病通常发生在男性进入60多岁和70多岁时。鉴于这些风险因素，退伍军人事务部越来越担心以前部署的美国退伍军人发展IPF的潜力。肺间质纤维化的主要特征之一是成纤维细胞在肺泡和肺泡间隔内积聚和持续存在。参与动态平衡修复过程的成纤维细胞在修复过程完成时会发生细胞凋亡。相比之下，IPF患者肺成纤维细胞对凋亡具有抵抗力。我们的实验室长期以来一直对成纤维细胞的凋亡和死亡受体Fas在这一过程中的作用感兴趣。本研究的重点在于IPF患者肺成纤维细胞对细胞凋亡的抵抗机制。在初步研究中，我们已经确定蛋白酪氨酸磷酸酶PTPN13(在小鼠中也称为PTP-BL)是人肺成纤维细胞抵抗Fas诱导的细胞凋亡的中央调节因子。PTPN13通过与Fas的C末端细胞质区域结合来抑制细胞凋亡，从而阻止所需的死亡信号分子FADD和caspase-8的募集。我们的初步研究表明，PTPN13是一个治疗靶点，当被拮抗时，将克服纤维化肺成纤维细胞对Fas诱导的细胞凋亡的抵抗。我们假设，干扰PTPN13功能将恢复纤维化肺成纤维细胞经历Fas诱导的凋亡的能力，导致肺成纤维细胞数量的进行性减少，从而解决已建立的纤维化。这一假设将通过三个具体目标进行检验。在目的1中，我们建议研究PTP-BL(人PTPN13的小鼠同源基因)的遗传缺陷对小鼠肺纤维化消退和未消退模型的影响。使用为这一建议开发的特定分析方法，包括成纤维细胞谱系追踪，我们建议调查PTP-BL缺陷对肺成纤维细胞数量和纤维化消退的影响。接下来，虽然PTP-BL的遗传缺陷是一个有用的实验工具，但我们的目标是将我们的工作迅速转化为人类。因此，我们开发了一条治疗流水线，以确定Fas和PTPN13之间相互作用的小分子抑制剂。使用高通量分析筛选20,831个小分子和FDA批准的药物，我们已经识别出3个分子，它们的行为类似于Fas序列，负责其与PTPN13的相互作用。这些小分子竞争性地抑制Fas和PTPN13之间的相互作用，并使肺成纤维细胞对Fas诱导的细胞凋亡敏感。此外，其中一个分子是FDA批准的药物，缩短了治疗开发的流水线。在目标2中，我们建议测试该药物在人源化小鼠模型中使成纤维细胞凋亡和解决已建立的肺纤维化的能力。最后，在目标3中，我们提出了研究PTPN13表达的调控机制。我们的初步研究表明，肺“僵硬”是这一事件的一个重要因素。综上所述，拟议的研究应该对成纤维细胞在肺纤维化中的持久性有新的理解，解决一个新的治疗靶点(PTPN13)，并提供FDA批准的重新调整用途的药物的概念验证数据，该药物被预测通过拮抗PTPN13功能来增加肺成纤维细胞的凋亡，并解决已建立的肺纤维化。

 DESCRIPTION (provided by applicant): Project summary Idiopathic pulmonary fibrosis (IPF) is a fatal fibrotic lung disease that compromises gas exchange in the alveoli. The median survival following diagnosis is approximately 3 years and there are few effective therapies. Although the specific causes of IPF are unknown, inhalation of dust, cigarette smoke and toxic chemicals are known risk factors for developing the disease, which most commonly develops in males as they enter their 60s and 70s. In view of these risk factors, the Department of Veterans Affairs has become increasingly concerned about the potential for previously deployed US Veterans to develop IPF. One of the cardinal features of IPF is the accumulation and persistence of fibroblasts in the alveoli and alveolar septa. Fibroblasts participating in homeostatic repair processes undergo apoptosis at the completion of the repair process. In contrast, fibroblasts from the lungs of IPF patients are resistant to apoptosis. Our lab has had a long-standing interest in fibroblast apoptosis and the role of the death receptor Fas in this process. This proposal is focused on the mechanisms that cause the resistance of lung fibroblasts from IPF patients to apoptosis. In preliminary studies, we have identified the protein tyrosine phosphatase, PTPN13 (also called PTP-BL in mice), as a central mediator of the resistance of human lung fibroblasts to Fas-induced apoptosis. PTPN13 inhibits apoptosis by binding to the C-terminal cytoplasmic region of Fas, thereby preventing recruitment of the required death signaling molecules FADD and caspase-8. Our preliminary studies suggest that PTPN13 is a therapeutic target, which, when antagonized, will overcome the resistance of fibrotic lung fibroblasts to Fas-induced apoptosis. We hypothesize that interfering with PTPN13 function will restore the ability of fibrotic lung fibroblasts to undergo Fas-induced apoptosis, leading to a progressive reduction in lung fibroblast numbers a resolution of established fibrosis. This hypothesis will be tested with 3 specific aims. In aim 1, we propose investigating the consequence of genetic deficiency of PTP-BL (the murine orthologue of human PTPN13) on resolving and non-resolving models of pulmonary fibrosis in mice. Using specific analytic methods developed for this proposal, including fibroblast lineage tracing, we propose investigating the effect of PTP-BL deficiency on lung fibroblast numbers and fibrosis resolution. Next, while genetic deficiency of PTP-BL is a useful experimental tool, our goal is to rapidly translate our work into humans. Consequently we have developed a therapeutic pipeline to identify small molecule inhibitors of the interaction between Fas and PTPN13. Using a high throughput assay to screen 20,831 small molecules and FDA-approved drugs, we have identified 3 molecules that behave as mimetics of the Fas sequence responsible for its interaction with PTPN13. These small molecules competitively inhibit the interaction between Fas and PTPN13 and sensitize lung fibroblasts to Fas-induced apoptosis. Furthermore, one of the molecules is an FDA-approved drug, shortening the pipeline for therapeutic development. In aim 2, we propose testing this drug for its ability to enable fibroblas apoptosis in a humanized mouse model and resolve established pulmonary fibrosis. Lastly, in aim 3 we proposed investigating the mechanisms controlling PTPN13 expression. Our preliminary studies suggest that lung "stiffness" is an important factor in this event. Collectivel, the proposed studies should innovative understanding of fibroblast persistence in pulmonary fibrosis, address a novel therapeutic target (PTPN13) and provide proof-of-concept data about a repurposed FDA-approved drug that by antagonizing PTPN13 function is predicted to augment lung fibroblast apoptosis and resolve established pulmonary fibrosis.