Defective FGFR2 Signaling in the Small Airway Basal Progenitor Cells in COPD

 描述(申请人提供)：小气道的病理变化是慢性阻塞性肺疾病(COPD)发病的关键因素，因为它们先于肺气肿的发展，并导致慢性阻塞性肺疾病的标志-进行性不可逆气流阻塞。然而，人类慢性阻塞性肺疾病相关小气道疾病的具体分子机制和细胞起源仍很大程度上尚不清楚。根据小鼠研究的知识，在远端呼吸道上皮祖细胞中通过成纤维细胞生长因子受体(FGFR)2的信号转导对于肺发育过程中远端肺上皮结构和分支形态的建立至关重要，我们的初步证据表明，在吸烟者和吸烟者COPD患者的小气道上皮(SAE)中，FGFR2途径下调与抑制远端肺表型的关键分子特征有关，并且FGFR2表达在基本细胞(BC)中，即呼吸道上皮的干/祖细胞，在那里它被吸烟和吸烟相关的表皮生长因子(EGF)和转化生长因子(TGF)-β抑制。该项目的中心假设是，吸烟依赖抑制COPD吸烟者SAE BC干/祖细胞中的FGFR2信号，使这些细胞产生正常分化的SAE的能力降低，并降低通过SAE修复和再生维持小气道完整性的能力。基于我们最近开发的从人类SAE中分离BC并在体外鉴定这些细胞的干/祖细胞功能的方法，本项目的目标是通过解决以下特定目标来验证这一中心假设：1.评估COPD吸烟者SAE中BC产生正常分化SAE和损伤后再生SAE的能力降低的假设，但相反，产生与体内COPD吸烟者SAE中存在的SAE类似的改变的SAE表型。目的2.验证FGFR2信号对人SAE BC与成人SAE分化和维持相关功能的重要作用的假设，以及吸烟相关因素抑制SAE BC将导致SAE BC表型改变的假设，与目标1中定义的COPD吸烟者SAE BC的表型相似。目的3.评估慢病毒载体介导的FGFR2过表达使COPD吸烟者SAE BC中FGFR2信号正常化的假设，应用FGFR2激活信号和抑制吸烟诱导的EGF和TGF-β通路将恢复这些细胞产生和维持正常分化SAE的能力。如果证实正确，恢复COPD吸烟者SAE BC中的FGFR2信号可能是一种新的治疗方法，可以在早期阶段防止COPD相关小气道疾病的进展。

 DESCRIPTION (provided by applicant): Pathologic changes in the small airways represent the key element in the pathogenesis of chronic obstructive pulmonary disease (COPD), as they precede the development of emphysema and contribute to progressive irreversible airflow obstruction, the hallmark of COPD. However, specific molecular mechanisms and cellular origin of COPD-associated small airway disorder in humans remain largely unknown. Based on the knowledge from murine studies that signaling via fibroblast growth factor receptor (FGFR) 2 in distal airway epithelial progenitors is critical for the establishment of distal lung epithelial architecture and branching morphogenesis during lung development, and our preliminary evidence that FGFR2 pathway is down-regulated in the small airway epithelium (SAE) of smokers and smokers with COPD in association with suppression of the key molecular features of the distal lung phenotype, and that FGFR2 is expressed in basal cells (BC), the stem/progenitor cells of the airway epithelium, where it is suppressed by smoking and smoking-associated epidermal growth factor (EGF) and transforming growth factor (TGF)-beta, the central hypothesis of this project is that smoking-dependent suppression of FGFR2 signaling in SAE BC stem/progenitor cells of COPD smokers renders these cells less potent in generating normally differentiated SAE and less capable of maintaining small airway integrity via SAE repair and regeneration. Capitalized on our recently developed methodology to isolate BC from the human SAE and characterize stem/progenitor functions of these cells in vitro, the goal of this project is to test this central hypothesis by addressing the following Specific Aims: Aim 1. T evaluate the hypothesis that BC from the SAE of COPD smokers have reduced capacity to generate normally differentiated SAE and regenerate SAE after injury but, instead, produce an altered SAE phenotype similar to that present in the SAE of COPD smokers in vivo. Aim 2. To test the hypothesis that FGFR2 signaling is important for human SAE BC function relevant to differentiation and maintenance of the adult human SAE and that suppression of SAE BC FGFR2 by smoking-related factors will result in an altered SAE BC phenotype similar to that exhibited by SAE BC of COPD smokers as defined in Aim 1. Aim 3. To assess the hypothesis that normalization of FGFR2 signaling in SAE BC of COPD smokers by lentiviral vector-mediated FGFR2 overexpression, application of FGFR2-activating signals and suppression of smoking-induced EGF and TGF-beta pathways will restore the capacity of these cells to generate and maintain normally differentiated SAE. If proven correct, restoration of FGFR2 signaling in SAE BC of COPD smokers could be a novel therapeutic approach to prevent progression of COPD-associated small airway disorder at the earliest stages.