Airway Submucosal Glands and Cystic Fibrosis Disease

描述(申请人提供)：囊性纤维化(CF)是由cAMP激活的阴离子通道-囊性纤维化跨膜电导调节因子(CFTR)编码基因的有害突变引起的。许多器官系统在CF中受到影响，但死亡通常是由肺部疾病引起的，其典型特征是产生异常稠密的粘液、严重的慢性细菌感染和支气管扩张。不幸的是，导致这种病理模式的潜在事件序列尚不清楚，也存在争议。我们长期以来的假设是，CFTR介导了气管-支气管腺黏膜下腺的液体分泌，这对于水合腺分泌物的大分子成分并将这种物质通过腺管冲洗到呼吸道表面是重要的。因此，在CF中，CFTR功能的丧失将导致腺体分泌过厚的粘液，并导致呼吸道表面睫状液的枯竭。因此，粘液纤毛运输中断，使呼吸道易于细菌定植。我们以前对猪呼吸道的研究表明，抑制阴离子和液体分泌会复制许多CF的肺部病理，包括粘液阻塞粘膜下腺、浓缩粘液分泌、睫状液耗竭和粘液纤毛运输障碍。通过目前的应用，我们提出了一系列研究，我们预计这些研究将加强这一假设。以猪呼吸道为模型，我们将为生理上重要的内源性分泌物定义细胞内信号转导元件的关键方面，这将有助于定义分泌是如何调节的，阐明CFTR所起的作用，并确定治疗操作的可能靶点。我们将获得并研究人类CF呼吸道，以证明在这种疾病中，哪些腺体分泌途径是失活的或完整的。我们将继续开发一种体外技术，通过利用shRNA来减少呼吸道组织外植体中CFTR的表达，从而在猪呼吸道中建立CF模型。使用阴离子和液体分泌抑制剂模拟猪呼吸道CF缺陷，我们将检查厚粘液对铜绿假单胞菌在呼吸道粘膜定植的影响。我们相信，这些研究将提供关键的新信息，关于气道腺在CF呼吸道疾病的肺部发病机制中的作用。毫无疑问，未来对CF治疗策略的发展将取决于对疾病过程的根本原因的更好理解。

DESCRIPTION (provided by applicant): Cystic Fibrosis (CF) is caused by deleterious mutations in the gene that codes for the cystic fibrosis transmembrane conductance regulator (CFTR), a cAMP-activated anion channel. Numerous organ systems are affected in CF, but death typically results from the lung disease which is typified by the production of unusually thick mucus, severe chronic bacterial infections, and bronchiectasis. Unfortunately, the underlying sequence of events which leads to this pattern of pathology is unclear and controversial. Our longstanding hypothesis is that CFTR mediates liquid secretion by tracheobronchial submucosal glands which is important for hydrating the macromolecular component of gland secretion and flushing this material through the gland ducts to the airway surface. Thereby, in CF, loss of CFTR function would lead to secretion of overly thick mucus from glands and depletion of periciliary fluid at the airway surface. Disruption of mucociliary transport thus occurs, predisposing the airways to bacterial colonization. Our previous studies of pig airways demonstrated that inhibition of anion and liquid secretion reproduces much of the lung pathology of CF including mucus occlusion of submucosal glands, secretion of inspissated mucus, depletion of periciliary fluid, and impaired mucociliary transport. With the present application, we propose a series of studies which we anticipate will strengthen this hypothesis. Using pig airways as a model, we will define critical aspects of the intracellular signal transduction elements for physiologically important endogenous secretogogues that will help define how secretion is regulated, clarify the role played by CFTR, and identify possible targets for therapeutic manipulation. We will obtain and study human CF airways to document which gland secretion pathways are disabled or intact in this disease. We will pursue development of an in vitro technique to model CF in porcine airways by utilizing shRNA to reduce CFTR expression in explants of airway tissue. Using anion and liquid secretion inhibitors to model the CF defect in pigs airways, we will examine the consequences of thick mucus on Pseudomonas aeruginosa colonization of the airway mucosa. We believe that these studies will provide crucial new information regarding the role of airway glands in the pulmonary pathogenesis of CF airway disease. Without doubt, development of future treatment strategies for CF will depend upon a better understanding of the underlying causes of the disease process.