Telomere Dysfunction as a cause of Chronic Lung Allograft Dysfunction

项目摘要 对于患有终末期肺部疾病的患者来说，肺移植是一个潜在的挽救生命的选择，例如 特发性肺纤维化(IPF)。然而，肺移植后的中位存活率低于 六年，主要受限于慢性同种异体肺移植功能障碍(CLAD)。新出现的数据表明， 端粒功能障碍，即在细胞复制过程中保护染色体的核蛋白帽，可以 导致IPF。目前尚不清楚端粒功能障碍是否也在CLAD中起作用。如果是这样的话， 同样需要移植的病理生理学也可能是它失败的原因。我们的初步数据 研究表明，肺移植供者外周血中端粒较短预示着肺内存活率下降 同种异体移植受者。我们还发现，气道祖细胞的端粒功能障碍足以 在实验性小鼠模型中诱导包裹体的病理特征。在人类中，祖细胞如 AS II型肺泡上皮细胞(AEC2)可以增殖和分化，以恢复上皮的完整性 受伤。因此，在端粒功能障碍的驱动下，AEC2的失效可能会导致肺泡上皮剥离，即 取而代之的是纤维组织。在这个奖项的支持下，我们将检验端粒的创新假设 功能障碍是CLAD的分子驱动因素。在研究目标1中，我们将评估端粒之间的联系 在一个庞大的、既定的、多中心的肺移植受者队列中，存在着遗传变异和包裹体。普普通通 导致端粒变短的遗传变异将被测序，端粒长度将由以下因素决定 定量聚合酶链式反应。我们将使用调整后的COX比例风险模型来评估供者之间的联系 端粒长度或基因型与无包膜存活时间的关系。这些发现将有助于区分这些贡献 先天和后天端粒功能障碍与移植后不良结局的关系。研究目标2将测试 纵向队列中同种异体移植AEC2短端粒与无包膜存活的关系。AEC2 端粒长度将通过与端粒特异探针(TELO-1)的荧光原位杂交来确定。 FISH)在与AEC2标记物表面活性蛋白C共同标记的经支气管镜活检组织上。 移植后60天内AEC2端粒长度与无包膜存活的关系 使用调整后的COX模型。这一目标将直接评估早期AEC2端粒功能障碍之间的联系 衣冠楚楚。在研究目标3中，我们将确定移植相关的肺损伤和淋巴细胞 炎症与包被时间有关，使用一种新的端粒介导包衣的小鼠模型 病理学。总体而言，这项拟议的调查有可能挑战我们对概念的理解 穿戴整齐，告知前沿的治疗干预措施。将端粒功能障碍作为一种分子 CLAD的驱动力将是新的范式，潜在地改变临床方法，从而改进 终末期肺部疾病患者的预后。

Project Summary Lung transplantation is a potentially lifesaving option for patients with end-stage lung diseases, such as idiopathic pulmonary fibrosis (IPF). However, the median survival following lung transplantation is less than six years, limited primarily by chronic lung allograft dysfunction (CLAD). Emerging data suggest that dysfunction of telomeres, the nucleoprotein caps that protect chromosomes during cellular replication, can result in IPF. It is unknown whether telomere dysfunction also plays a role in CLAD. Were that to be the case, the same pathophysiology that necessitated transplant might also underlie its failure. Our preliminary data show that shorter telomeres in peripheral blood of lung allograft donors predict decreased survival in lung allograft recipients. We also have found that telomere dysfunction in airway progenitor cells is sufficient to induce the pathologic hallmarks of CLAD in an experimental murine model. In humans, progenitor cells such as type II alveolar epithelial cells (AEC2) can proliferate and differentiate to restore epithelial integrity following injury. Thus, AEC2 failure, driven by telomere dysfunction, could lead to denuded alveolar epithelium that is replaced by fibrotic tissue. With the support of this award, we will test the innovative hypothesis that telomere dysfunction is a molecular driver of CLAD. In Study Aim 1, we will evaluate the associations between telomere genetic variants and CLAD in a large, established, multi-center cohort of lung transplant recipients. Common genetic variants resulting in short telomeres will be sequenced, and telomere length will be determined by quantitative PCR. We will use adjusted Cox proportional hazards models to evaluate the links between donor telomere length or genotype and CLAD-free survival time. These findings will help distinguish the contributions of innate and acquired telomere dysfunction to poor post-transplant outcomes. Study Aim 2 will test the association between short allograft AEC2 telomeres and CLAD-free survival in a longitudinal cohort. AEC2 telomere length will be determined by fluorescence-in situ hybridization with a telomere-specific probe (Telo- FISH) on transbronchial biopsy tissues co-labeled with the AEC2 maker, surfactant protein C. We will test the association between AEC2 telomere length within the first 60 days post-transplant and CLAD-free survival using adjusted Cox models. This aim will directly assess the link between early AEC2 telomere dysfunction and CLAD. In Study Aim 3, we will determine whether transplant-associated lung injury and lymphocytic inflammation are associated with time to CLAD, using a novel murine model of telomere-mediated CLAD pathology. Overall, this proposed investigation has the potential to challenge our conceptual understanding of CLAD and inform cutting edge therapeutic interventions. Establishing telomere dysfunction as a molecular driver of CLAD would be new paradigm, potentially transforming clinical approaches and thus improving outcomes for patients with end-stage lung disease.