Role of Mucin in Lung Homeostasis and Pathophysiology

描述（由申请人提供）：粘液分泌过多和气道高反应性（AHR）是哮喘、囊性纤维化（CF）和慢性阻塞性肺疾病（COPD）的重要特征。尽管存在这些公认的病理关联，但呼吸道粘液的主要糖蛋白成分（分泌的聚合粘蛋白）介导AHR的机制尚不清楚。尸检研究表明，死于致命性哮喘的患者中，98%的呼吸道存在广泛的粘液堵塞。MUC5AC和MUC5B是主要的气道粘液蛋白。它们的产生（尤其是MUC5AC）在哮喘、CF和COPD以及这些疾病的动物模型中显著增加。此外，阻断粘液分泌可使AHR降低约80%。这些发现为本提案的总体目标提供了基础，即评估粘液分泌对肺功能的功能影响。该提案的中心假设是分泌Muc5ac和Muc5b通过促进粘液增厚、气道管腔阻塞和远端气道关闭在气道高反应性的发展中起重要作用。研究将在人气道上皮细胞培养和敲除小鼠中进行，以达到以下具体目的：目的1：确定聚合粘蛋白分泌在黏液层增厚中的作用。目的2：确定聚合粘蛋白分泌对AHR的功能影响。公共卫生相关性：粘液分泌过多和分泌过多是哮喘、囊性纤维化（CF）和慢性阻塞性肺疾病（COPD）的发病率和死亡率密切相关的主要特征。我们的研究旨在了解粘液是如何分泌的，它在肺部疾病中是如何改变的，以及它们的功能后果是什么，使用基因工程小鼠和培养细胞。这些目标的实现将为阻塞性肺疾病的新治疗方法提供见解。

DESCRIPTION (provided by applicant): Mucus hypersecretion and airway hyperreactivity (AHR) are significant features of asthma, cystic fibrosis (CF), and chronic obstructive pulmonary disease (COPD). In spite of these well-recognized pathological associations, the mechanisms by which AHR is mediated by the chief glycoprotein components of respiratory mucus, the secreted polymeric mucins, are unknown. Autopsy studies show that 98% of the airways of patients who die from fatal asthma have extensive mucus plugging. MUC5AC and MUC5B are the major secreted airway mucins. Their production (especially that of MUC5AC) increases significantly in asthma, CF, and COPD, and in animal models of these diseases. Furthermore, blockade of mucus secretion reduces AHR by ~80%. These findings provide the basis for the overall goal of this proposal, which is to assess the functional consequences of mucus secretion on lung function. The central hypothesis of this proposal is that secreted Muc5ac and Muc5b play essential roles in the development of airway hyperreactivity by promoting mucus thickening, airway lumen occlusion, and distal airway closure. Studies will be conducted in human airway epithelial cell cultures and knockout mice in order to achieve the following specific aims: Aim 1: Determine the role of polymeric mucin secretion in mucus layer thickening. Aim 2: Determine the functional consequences of polymeric mucin secretion on AHR. PUBLIC HEALTH RELEVANCE: Mucus overproduction and hypersecretion are cardinal features that are strongly associated with morbidity and mortality in asthma, cystic fibrosis (CF), and chronic obstructive pulmonary disease (COPD). Our studies are aimed at understanding how mucus is secreted, how it is altered in lung disease, and what the functional consequences of these are, using genetically engineered mice and cells grown in culture. Achievement of these goals will provide insights into novel treatments of obstructive lung diseases.