Mechanistic evaluation of a novel Wnt-responsive adult alveolar epithelial progenitor population during regeneration after diffuse alveolar damage

项目摘要 哺乳动物肺的肺泡区域是一种复杂的、精确结构的组织，其是肺的主要功能所需的。 呼吸系统、气体交换和组织氧合的功能。肺泡上皮损伤 在包括急性呼吸窘迫综合征（ARDS）在内的人类肺部疾病中起着核心作用， 流行的、高影响的临床疾病，影响了美国5%的机械通气患者， 发达世界。急性呼吸窘迫综合征（ARDS）的死亡率接近40%，存活者的康复率为100%。 艰苦，多系统残疾的巨大负担持续5年或更长时间， 住院重要的是，虽然许多ARDS幸存者恢复了肺功能，但仍有一部分患者发展为 肺功能持续异常、肺部瘢痕形成的影像学证据和肺部症状 即使是在ARDS之后的几年。到目前为止，还没有关于指导ARDS恢复的机制的数据。 发展改善ARDS后恢复和促进肺再生的策略的关键要求是 了解肺中的祖细胞群体，以及它们在复杂的，区域化的肺疾病中的具体作用。 损伤后的再生我们已经发现了一组独特的Wnt反应性AT2细胞。这些细胞包括 不同的祖细胞亚系，我们称之为AEP（Axin2+肺泡上皮祖细胞）。AEP能够 在体内和体外产生AT 1和AT 2细胞，在肺泡稳态期间稳定9个月， 并且在弥漫性肺泡损伤后迅速扩张以再生大部分肺泡上皮。 重要的是，我们已经鉴定了一种AEP富集的细胞表面受体，其标记小鼠和小鼠中的AEP。 人肺，其允许人AEP作为祖细胞谱系的功能验证。 直接比较小鼠和人的AEP的能力提供了对可能的 AEP功能所需的上游信号和下游效应物。这项提案的科学目的是 直接评估肺内AEP生物学中几个候选因子的要求和作用， 再生，特别强调Wnt和Fgf信号在促进AEP中的组合作用 功能该提案的目的是：1）定义AEP生物学中Wnt信号传导的要求， 肺泡再生和2）确定FGFR 2信号传导和ETS转录因子在AEP中的功能。 这项建议的另一个重要目标是提供一个结构化、重点突出的培训计划， 主要研究员开发再生生物学研究技术的先进设备 并允许成功过渡到独立。

PROJECT SUMMARY The alveolar region of the mammalian lung is a complex, precisely structured tissue required for the primary functions of the respiratory system, gas exchange and tissue oxygenation. Damage to the alveolar epithelium plays a central role in human lung diseases including Acute Respiratory Distress Syndrome (ARDS), a prevalent, high impact clinical disorder that affects up to 5% of mechanically ventilated patients in the developed world. The mortality rate of ARDS approaches 40%, and the recovery for ARDS survivors is arduous, with a substantial burden of multi-system disability continuing 5 or more years following hospitalization. Critically, while many ARDS survivors recover lung function, a subset of patients develops persistently abnormal pulmonary function, imaging evidence of pulmonary scarring, and pulmonary symptoms even years after ARDS. To date, no data exists regarding the mechanisms that guide ARDS recovery. A key requirement for developing strategies to improve recovery after ARDS and promote lung regeneration is to understand progenitor populations in the lung, and their specific roles in the complex, regionalized nature of regeneration after injury. We have found a distinct group of Wnt-responsive AT2 cells. These cells comprise a distinct progenitor sublineage, which we call AEPs (Axin2+ Alveolar Epithelial Progenitors). AEPs are capable of generating both AT1 and AT2 cells in vivo and in vitro, are stable for 9 months during alveolar homeostasis, and expand rapidly to regenerate a majority of the alveolar epithelium after diffuse alveolar damage. Importantly, we have identified an AEP-enriched cell surface receptor that marks AEPs in both mouse and human lung, which has allowed functional validation of human AEPs as a progenitor lineage. The ability to directly compare AEPs from mouse and human has provided specific insight into possible upstream signals and downstream effectors required for AEP function. The scientific objective of this proposal is to directly evaluate the requirement and role for several such candidate factors in AEP biology during lung regeneration, with a specific emphasis on the combinatorial role of Wnt and Fgf signals in promoting AEP function. The Aims of the proposal are 1) Define the requirement for Wnt signaling in AEP biology during alveolar regeneration and 2) Determine the function of FGFR2 signaling and ETS transcription factors in AEPs. The other crucial objective of this proposal is to provide for a structured, focused training plan to allow the primary investigator to develop an advanced armamentarium of research techniques in regenerative biology and allow for a successful transition to independence.