Fungal Exposure and the Respiratory Tract Microbiome

描述（由申请人提供）：呼吸系统是一个中心宿主-环境界面，每天暴露于数十亿颗粒和病原体。呼吸道粘液对于清除沉积的环境因子和通过称为粘液纤毛清除（MCC）的过程限制病原体积累至关重要。粘液的产生和组成在许多肺部疾病中发生显著改变。最近的研究已经确定了哮喘和COPD中肺部微生物组的变化，但尚未测试MCC功能改变与呼吸道微生物组变化之间的直接联系。在这个探索性的拨款提案中，真菌毒素暴露导致上呼吸道和下呼吸道微生物组发生变化的机制将被确定，沿着这些变化的功能后果。这项工作的重点是气道粘液的主要大分子成分-粘蛋白糖蛋白编码的MUC 5AC和MUC 5 B基因。最近在哮喘和COPD患者中的研究表明，粘液产生的改变与MUC 5AC（上升）和MUC 5 B（保持稳定表达或下降）的差异调节有关。为了解决粘蛋白是否决定呼吸道微生物多样性，最近产生了Muc 5ac和Muc 5 b敲除小鼠。在没有炎症激发的情况下，Muc 5 b（而不是Muc 5ac）缺陷会导致自发性致死性感染，其标志是获得肺部金黄色葡萄球菌感染。因此，Muc 5 b对于控制肺中的稳态和病理微生物种群是必不可少的。在此，目的是实现该RFA的主要目的-在呼吸道炎症的小鼠模型中测试“环境暴露如何影响微生物组的组成和/或功能”。曲霉菌属真菌暴露是哮喘恶化和几种类型的过敏性肺炎（一种相关的职业性肺病）的主要原因。在初步研究中，暴露于气溶胶曲霉提取物（AOE）的野生型小鼠显示炎症，Muc 5ac增加，Muc 5 b表达减少，与哮喘患者相似。因此，假设AOE诱导的呼吸道微生物组组成的变化取决于Muc 5 b表达水平，并且这些变化影响疾病病理学和对机会性病原体感染的易感性。为了测试这一点，将野生型小鼠暴露于 雾化AOE。将测量上下呼吸道微生物群的变化，我们将评估炎症、组织病理学和对沙门氏菌易感性的变化。金黄色。将这些数据与Muc 5 b缺陷和Muc 5 b过表达小鼠中观察到的数据进行比较。总的来说，这些研究将用于开发一个框架，用于设计和分析小鼠和人类的后续研究。MUC 5 B在人类中的表达差异很大，常见的遗传多态性显著调节其表达。此外，吸入高渗盐水等治疗可有效增强MCC。因此，成功完成拟议的研究可能会在短期内对人类健康产生重大影响。

DESCRIPTION (provided by applicant): The respiratory system is a central host-environment interface that is exposed to billions of particles and pathogens daily. Airway mucus is critical fo eliminating deposited environmental agents and limiting pathogen accumulation through a process called mucociliary clearance (MCC). Mucus production and composition are dramatically altered in numerous lung diseases. Recent studies have identified changes in the lung microbiome in asthma and COPD, but direct links between altered MCC function and changes in the respiratory microbiome have not been tested. In this exploratory grant proposal, mechanisms by which fungal toxicant exposure elicits changes will be identified in the upper and lower respiratory tract microbiomes along with the functional consequences of these changes. This work focuses on the major macromolecular components of airway mucus - mucin glycoproteins encoded by the MUC5AC and MUC5B genes. Recent studies in patients with asthma and COPD show that alterations in mucus production are related to differential regulation of MUC5AC (which goes up) and MUC5B (which remains stably expressed or goes down). To address whether mucins determine respiratory microbial diversity, Muc5ac and Muc5b knockout mice were recently generated. In the absence of an inflammatory challenge, Muc5b (but not Muc5ac) deficiency causes spontaneous lethal infections marked by acquisition of pulmonary Staphylococcus aureus infection. Thus, Muc5b is essential for controlling homeostatic and pathological microbial populations in the lungs. Here, the intent is to accomplish the primary purpose of this RFA - to test "how environmental exposures impact the composition and/or function of the microbiome" - in mouse models of respiratory inflammation. Aspergillus fungal exposure is a major cause of asthma exacerbations and several types of hypersensitivity pneumonitis, a related occupational lung disease. In preliminary studies, wild type mice exposed to an aerosol Aspergillus oryzae extract (AOE) show inflammation, increased Muc5ac, and reduced Muc5b expression similar to that seen in humans with asthma. Thus, it is hypothesized that AOE-induced changes in respiratory microbiome composition are dependent upon Muc5b expression levels and that these changes affect disease pathology and susceptibility to opportunistic pathogen infection. To test this, wild type mice will be exposed to aerosolized AOE. Changes will be measured in the upper and lower airway microbiota, and we will assess changes in inflammation, histopathology, and susceptibility to S. aureus. These data will be compared to that seen in Muc5b deficient and Muc5b overexpressing mice. Collectively, these studies will be used to develop a framework for designing and analyzing subsequent investigations in mice and in humans. MUC5B expression varies significantly in humans, and common genetic polymorphisms significantly regulate its expression. In addition treatments such as inhaled hypertonic saline enhance MCC effectively. Thus, successful completion of the proposed studies may significantly impact human health in the near-term.