Therapeutic Targeting of PTPN13 in Idiopathic Pulmonary Fibrosis

 描述（由申请人提供）： 特发性肺纤维化（IPF）是一种致命的纤维化肺部疾病，损害肺泡中的气体交换。诊断后的中位生存期约为3年，有效的治疗方法很少。虽然IPF的具体原因尚不清楚，但吸入灰尘、香烟烟雾和有毒化学物质是已知的发病风险因素，最常见于60多岁和70多岁的男性。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生IPF的可能性。IPF的主要特征之一是成纤维细胞在肺泡和肺泡隔中的积聚和持续存在。参与稳态修复过程的成纤维细胞在修复过程完成时经历凋亡。相反，来自IPF患者肺的成纤维细胞对细胞凋亡具有抗性。我们的实验室长期以来一直对成纤维细胞凋亡和死亡受体Fas在此过程中的作用感兴趣。该提案重点关注导致IPF患者肺成纤维细胞对细胞凋亡抵抗的机制。在初步的研究中，我们已经确定了蛋白酪氨酸磷酸酶，PTPN 13（也称为PTP-BL在小鼠），作为一个中央调解人肺成纤维细胞Fas诱导的细胞凋亡的阻力。PTPN 13通过与Fas的C-末端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和半胱天冬酶-8的募集。我们的初步研究表明，PTPN 13是一个治疗靶点，当被拮抗时，它将克服纤维化肺成纤维细胞对Fas诱导的凋亡的抵抗。我们假设干扰PTPN 13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。将通过3个具体目标对该假设进行检验。在目的1中，我们提出研究PTP-BL（人PTPN 13的小鼠直向同源物）的遗传缺陷对小鼠肺纤维化的消退和非消退模型的后果。使用为此提议开发的特定分析方法，包括成纤维细胞谱系追踪，我们建议研究PTP-BL缺乏对肺成纤维细胞数量和纤维化解决的影响。接下来，虽然PTP-BL的遗传缺陷是一种有用的实验工具，但我们的目标是将我们的工作快速转化为人类。因此，我们已经开发了一种治疗管道来鉴定Fas和PTPN 13之间相互作用的小分子抑制剂。使用高通量测定筛选20，831种小分子和FDA批准的药物，我们已经鉴定了3种分子，其表现为负责其与PTPN 13相互作用的Fas序列的模拟物。这些小分子竞争性抑制Fas和PTPN 13之间的相互作用，并使肺成纤维细胞对Fas诱导的凋亡敏感。此外，其中一种分子是FDA批准的药物，缩短了治疗开发的管道。在目标2中，我们建议测试这种药物在人源化小鼠模型中使纤维化细胞凋亡并解决已建立的肺纤维化的能力。最后，在目标3中，我们提出研究控制PTPN 13表达的机制。我们的初步研究表明，肺“僵硬”是一个重要因素，在这一事件。总的来说，所提出的研究应该创新性地理解肺纤维化中的成纤维细胞持久性，解决新的治疗靶点（PTPN 13），并提供关于FDA批准的药物的概念验证数据，该药物通过拮抗PTPN 13功能，预计可增加肺成纤维细胞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.