Project 3: Membrane-bound mucins on the airway surface ensure efficient mucus clearance and lung health

项目 3：气道表面的膜结合粘蛋白确保有效的粘液清除和肺部健康

• 批准号: 10684209
• 负责人: BRIAN M BUTTON
• 金额: $ 54.43万
• 依托单位: UNIV OF NORTH CAROLINA CHAPEL HILL
• 依托单位国家: 美国
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-08-15 至 2027-07-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10684209
• 关键词: Acceleration; Address; Affect; Airway Disease; Asthma; Binding; CRISPR-mediated transcriptional activation; Cell surface; Cells; Chronic Obstructive Pulmonary Disease; Cilia; Cystic Fibrosis; Data; Defense Mechanisms; Disease; Distal; Ensure; Evolution; Failure; Force of Gravity; Gel; Glycocalyx; Goals; Health; Hydration status; Infection; Inhalation; Innate Immune System; Investigation; Link; Lung; Mediating; Membrane; Modeling; Molecular; Motion; Mucins; Mucociliary Clearance; Mucous Membrane; Mucous body substance; Pathogenesis; Penetration; Persons; Play; Polysaccharides; Power stroke; Production; Property; Pump; Role; Structure; Surface; System; Technology; Testing; Therapeutic; Virus; Virus Diseases; Viscosity; Water; airway epithelium; density; genetic approach; glycosylation; hydrodynamic flow; lung health; mucus clearance; mucus-associated lung diseases; novel; particle; pathogen; prevent; respiratory; transmission process; viscoelasticity; water flow

The healthy airway epithelial mucosal barrier is the center of a powerful innate immune system that protects the pulmonary surfaces from the constant onslaught of inhaled infectious and noxious substances. However, abnormalities in the mucus clearance system characterize a number of airway diseases, including cystic fibrosis, chronic obstructive lung disease, and asthma. The pathogenesis of these diseases is multi-factorial, but appears to include a common disease-initiating step, a reduction of mucus clearance. We have developed a novel paradigm describing the mucus transport system, referred to as the “two-gel” model, which highlights the role of the two mucin-containing layers on the airway surface: 1) the mucus layer, containing secreted mucins which bind inhaled particles; and 2) membrane-spanning tethered mucins – a layer referred to as the periciliary layer- glycocalyx (or PCL-G) which lines the airway surface. We have previously shown that the failure to regulate both layers is associated with a reduction in mucociliary clearance. However, it is currently unknown how the cilia and PCL-G are organized to facilitate the efficient clearance of mucus out of the lungs and protect against inhaled pathogens. The overarching goal of Project 3 of this PPG is to apply novel theoretical concepts and experimental approaches to answer key questions about the multiple roles of the PCL-G with respect to both mucus transport and the host barrier defense activities required to protect the airway surfaces. First, we seek to understand how the mucus layer actually is transported, i.e., how momentum is transferred from cilia to the mucus layer. In Aim 1, we will test the hypothesis that in the distal airways, where mucins are too low to generate a viscoelastic gel, water is “pumped out” of the periciliary space, providing hydrodynamic force sufficient to transport the dilute mucus layer. Studies in this aim are directed at quantifying the water pumping forces generated by cilia beating, assess whether they are sufficient to propel a low-viscosity mucus across airway surfaces, and understand the impact of gravity. In Aim 2, we will test the hypothesis that in the larger airways, where mucin concentrations are sufficient to form a viscoelastic gel, a second mode of cilia-mucus momentum transfer is required for efficient mucus transport. Here, we hypothesize that the highly glycosylated tethered mucins on the tips of cilia form weak/transient interactions with the mucus gel during the cilia power stroke and physically “thrust” the mucus gel forward. Studies here will assess the impact of modulating tethered mucins on the efficacy of mucus gel transport and how it is altered in disease. Studies in Aim 3 are directed at understanding the role that the densely packed tethered mucins play in airway protection. We will test the hypothesis that tethered mucins lining the airway surface form a physical barrier to prevent inhaled pathogens, including viruses, from penetrating the PCL-G space. We anticipate that results from these studies will lead to paradigm shifts in our understanding of how mucus clearance is maintained in health and aid in the discovery of therapeutic strategies which can accelerate/restore clearance in persons with muco-obstructive lung diseases.

健康的气道上皮粘膜屏障是强大的先天免疫系统的中心，可保护 肺部表面免受吸入的传染性和有毒物质的持续攻击。然而， 粘液清除系统异常是许多气道疾病的特征，包括囊性纤维化、 慢性阻塞性肺病和哮喘。这些疾病的发病机制是多因素的，但似乎 包括一个常见的疾病引发步骤，即粘液清除的减少。我们开发了一本小说 描述粘液运输系统的范式，称为“双凝胶”模型，它强调了粘液运输系统的作用 气道表面的两个含粘蛋白层：1）粘液层，含有分泌的粘蛋白， 结合吸入颗粒； 2）跨膜束缚粘蛋白——称为纤毛周围层的层—— 气道表面的糖萼（或 PCL-G）。我们之前已经表明，未能对两者进行监管 层数与粘膜纤毛清除率的降低有关。然而，目前尚不清楚纤毛和 PCL-G 的组织有助于有效清除肺部粘液并防止吸入 病原体。该 PPG 项目 3 的总体目标是应用新颖的理论概念和实验 回答有关 PCL-G 在粘液运输方面的多重作用的关键问题的方法 以及保护气道表面所需的宿主屏障防御活动。首先，我们试图了解如何 粘液层实际上是运输的，即动量如何从纤毛转移到粘液层。瞄准 1，我们将测试以下假设：在远端气道中，粘蛋白太低而无法生成粘弹性凝胶， 水被从纤毛周围空间“泵出”，提供足以输送稀释液的水动力 粘液层。此目的的研究旨在量化纤毛跳动产生的抽水力， 评估它们是否足以推动低粘度粘液穿过气道表面，并了解 重力的影响。在目标 2 中，我们将检验以下假设：在较大气道中，粘蛋白浓度为 足以形成粘弹性凝胶，需要第二种纤毛-粘液动量传递模式才能有效 粘液运输。在这里，我们假设纤毛尖端高度糖基化的束缚粘蛋白形成 在纤毛动力冲程期间与粘液凝胶微弱/短暂的相互作用并物理地“推动”粘液凝胶 向前。这里的研究将评估调节束缚粘蛋白对粘液凝胶运输功效的影响 以及它在疾病中如何改变。目标 3 中的研究旨在了解密集堆积的作用 束缚粘蛋白起到气道保护作用。我们将检验气道内壁粘蛋白的假设 表面形成物理屏障，防止吸入的病原体（包括病毒）穿透 PCL-G 空间。我们预计这些研究的结果将导致我们对如何理解的范式转变 维持健康的粘液清除并有助于发现可以治疗的策略 加速/恢复患有粘液阻塞性肺部疾病的人的清除率。