Project 1: Mechanism of action of mucolytics in improving mucus clearance in lung disease

患有粘膜阻塞性肺病（CF、COPD和哮喘）的患者遭受粘液清除能力降低 这是由于在他们的气道中积累了粘性的、粘附的粘液。为了了解其发病机制， 对于这些疾病，有必要了解介导有效粘液清除的机制， 健康以及该系统的改变如何导致这些疾病中的每一种的粘液清除失败。我们 总体假设是，疾病中粘液清除减少是由于多个改变的结果， 气道粘液的组成和物理性质。根据我们的初步数据， 粘液性质是由于：1）疾病相关的粘液浓度增加，2） MUC5AC（主要哮喘粘蛋白）与MUC5B（主要CF/COPD粘蛋白）的比率，和/或3） 粘蛋白的氧化导致额外的交联。我们假设粘液层的这种变化 将产生更"粘"（更粘稠、粘附、抗撕裂）的粘液， 纤毛跳动和咳嗽的动作。目前还不知道这种变化是如何发生的。 粘液改变了粘液的生物物理学性质，以及这些变化如何导致粘液清除率降低。 为了回答这些问题，目标1中的研究旨在测试改变粘液浓度的影响， 和MUC5AC：MUC5B比率对粘液生物物理性质（流变学、粘附和内聚强度，以及 摩擦）以及这些改变如何影响咳嗽和纤毛跳动引起的粘液清除率。一旦 已经确定了疾病如何改变粘液清除，我们的目标，以支持tPPG临床项目3和4 是确定如何最好地恢复粘液阻塞患者的粘液清除。我们假设 有两种独立但互补的方法来从气道清除粘附的粘液。的 最简单的是通过水合作用降低粘液浓度。第二是打破结构， 通过使用还原剂降低粘蛋白分子量来减少粘液。重要的是，我们假设， 这些方法可以是相加的/协同的。在目标2中，我们将通过将减少 药物介导的粘蛋白分子量/大小变化与水化介导的粘液变化相结合 浓度对粘液生物物理性质变化的影响，并评估这些变化对 刺激纤毛和咳嗽介导的粘液清除。在目标3中，我们将评估炎症的作用- 介导的粘液氧化，形成渗透性的、非溶胀性的粘液凝胶， 限制与气道的间隙。我们将测试的假设，水化方法本身是不够的，但一个 需要水合剂加还原剂的组合来恢复粘液清除。总体而言，研究 项目1中的技术支持，通过提高我们对机制的理解来支持其他tPPG项目 疾病中有缺陷的粘液清除，并确定最有效的治疗组合， 和还原剂，以最大限度地恢复CF、COPD和哮喘患者的粘液清除。

Patients with muco-obstructive lung diseases (CF, COPD, and asthma) suffer from reduced mucus clearability due to accumulation of sticky, adherent, mucus in their airways. In order to understand the pathogenesis of these diseases, it is necessary to understand both the mechanisms that mediate efficient mucus clearance in health and how alterations in this system leads to failed mucus clearance in each of these disorders. Our overarching hypothesis is that reduced mucus clearance in disease is a result of multiple alterations in the composition and physical properties of the airway mucus. Based on our preliminary data, such changes in mucus properties come as a result of: 1) disease-related increases in mucus concentration, 2) alteration in the ratio of MUC5AC (the dominant asthma mucin) vs. MUC5B (the dominant CF/COPD mucin), and/or 3) oxidation of mucins resulting in additional cross-links. We hypothesize that such alterations in the mucus layer will produce a more “sticky” (more viscous, adherent, tear-resistant) mucus that will be harder to be cleared by the action of cilia beating and coughing. There is currently a lack of knowledge of how such changes in the mucus alter the biophysics properties of the mucus and how such changes lead to reduced mucus clearance. To answer these questions, studies in Aim 1 are designed to test the effect of altering mucus concentration and MUC5AC:MUC5B ratio on mucus biophysical properties (rheology, adhesion and cohesion strength, and friction) and how such alterations affect the rate of mucus clearance by cough and cilia beating. Once it has been established how disease alters mucus clearance, our goal, in support of the tPPG clinical projects 3 & 4 is to determine how best to restore mucus clearance in patients with mucus obstructions. We hypothesize that there are two separate, but complementary, approaches to clear adherent mucus from the airways. The simplest is to reduce the mucus concentration, via hydration. The second is by breaking down the structure of mucus through reduction in mucin molecular weight using reducing agents. Importantly, we hypothesize that such approaches may be additive/synergistic. In Aim 2 we will test these hypotheses by correlating reducing agent-mediated changes in mucin molecular weight/size combined with hydration-mediated changes in mucus concentration on changes in mucus biophysical properties and assess the impact of these changes on stimulating both cilia- and cough-mediated mucus clearance. In Aim 3, we will assess the role of inflammation- mediated oxidation of mucus in the formation of a permeant, non-swellable, mucus gel, which can severely limit clearance from the airways. We will test the hypothesis that hydration method alone is not sufficient, but a combination of hydrator plus a reducing agent is required to restore the mucus clearance. Overall, the studies in Project 1 are expected to support other tPPG Projects by advancing our understanding of the mechanism(s) of defective mucus clearance in disease and identifying the most effective therapeutic combination of hydrating and reducing agents to maximally restore mucus clearance in patients with CF, COPD, and asthma.