Host microbiota and airway mucus: a novel paradigm for lung defense and immune homeostasis during early post-natal development

气道粘液清除是肺的主要防御机制， 代表肺健康的关键“易感性窗口”。围产期变化的关键组成部分， 粘液清除系统已定性描述，但这些细节和功能意义， 变化未知。我们在小鼠和人类中的初步数据表明：1）气道粘液成分是 发育调节;和2）粘液清除系统的组成部分受以下状态的影响： 宿主的微生物我们已经确定了一种可测试的机制，将宿主微生物群与 新生儿气道粘液生物学和肺内稳态，即，IL-22+ ILC 3介导的肠-肺轴。我们也 证实人类在有助于气道粘液清除的关键因素方面表现出年龄依赖性变化， 例如，在一个实施例中，MUC 5AC水平。为了验证这些假设，我们提出了以下目标：1）测试宿主是否 微生物群生态失调或IL-22+ ILC 3介导的肠-肺轴的阻断影响丰度， 新生小鼠与成年小鼠中气道粘液的组成和功能。在无菌环境中饲养的同类小鼠 或无特定病原体的疾病，无论是初治还是接受抗生素治疗，都将在纳塔尔后进行评估 （PND）10和PND 66用于：1）支气管肺泡灌洗（BAL）蛋白质组成、粘液浓度，和 分泌的粘蛋白定量; 2）气道粘膜纤毛清除;和3）肺mRNA测序。具体 将评估IL-22信号传导和结果在气道表面脱水背景下的作用 分别使用IL-22 KO小鼠和Scnn 1b-Tg小鼠。宿主微生物群的变化将由 细菌16 S核糖体RNA基因定量。2)为了测试CF样宿主微生物群生态失调是否 影响新生小鼠中正常的IL-22+ ILC 3介导的肠-肺轴的建立。同类系 在PND 10时，将使用未经处理或接受抗生素治疗的BNF 508 CF小鼠和WT同窝小鼠研究 参考其肠道微生物群的定量分析，IL 22 + ILC 3细胞流入肺。同时，肺 和BAL样品，以评估CF肠道生态失调对早期肺转录组的影响， 新生儿呼吸道分泌物的组成。与Scnn 1b-Tg小鼠的杂交将用于加剧 CF 508 CF肺表型。3)为了测试“健康”气道粘液的组成是否代表年龄- 依赖性的数量差异。从气管插管中采集的气道粘液样本 用于无以下病史或症状的新生儿/婴儿/儿童（0-5岁）和成人（25-40岁） 将分析呼吸道疾病的粘蛋白和蛋白质组成。组织学标本来自 肺MAP 生物储存库（BRINDL） 将探测特定粘液的mRNA和蛋白质表达 标记。完成这些目标将建立一个新的概念框架，并提供急需的 实验证据，以研究发病机制，开发治疗方法，并占主机 微生物群对“早期”肺部健康和早发性粘膜阻塞性肺病的影响。

Airway mucus clearance is a primary lung defense mechanism and the early neonatal period represents a critical “window of susceptibility” for lung health. Perinatal changes in key components of the mucus clearance system have been qualitatively described, but the details and functional significance of these changes are unknown. Our preliminary data in mice and humans indicate that: 1) airway mucus composition is developmentally regulated; and 2) components of the mucus clearance system are affected by the status of the host microbiota in early life. We have identified a testable mechanism to link the host microbiota with neonatal airway mucus biology and lung homeostasis, i.e., the IL-22+ILC3-mediated gut-lung axis. We also posit that humans exhibit age-dependent changes in key elements contributing to airway mucus clearance, e.g., MUC5AC levels. To test these hypotheses, we propose the following aims: 1) To test whether host microbiota dysbiosis or blockade of the IL-22+ILC3-mediated gut-lung axis affect the abundance, composition, and function of airway mucus in neonatal vs. adult mice. Congenic mice raised in germ-free or specific-pathogen free conditions, either naïve or treated with antibiotics, will be assessed at post natal day (PND)10 and PND66 for: 1) bronchoalveolar lavage (BAL) protein composition, mucus concentration, and secreted mucins quantification; 2) airway mucociliary clearance; and 3) lung mRNA sequencing. Specific contributions of IL-22 signaling and outcomes in the context of airway surface dehydration will be assessed using IL-22 KO mice and Scnn1b-Tg mice, respectively. Changes in host microbiota will be determined by bacterial 16S ribosomal RNA gene quantification. 2) To test whether CF-like host microbiota dysbiosis affects the establishment of the normal, IL-22+ILC3-mediated gut-lung axis in neonatal mice. Congenic ∆F508 CF mice and WT littermates, either naïve or treated with antibiotics, will be used at PND10 to study the influx of IL22+ILC3 cells into the lung referenced to quantitative analysis of their gut microbiota. In parallel, lung and BAL samples will be collected to assess the effect of CF gut dysbiosis on the early lung transcriptome and the composition of neonatal airway secretions. Crosses with Scnn1b-Tg mice will be used to exacerbate the ∆F508 CF lung phenotype. 3) To test whether the composition of “healthy” airway mucus presents age- dependent, quantitative differences in humans. Airway mucus samples harvested from endotracheal tubes used in neonates/infants/children (0-5 years old) and adults (25-40 years old) with no history or symptoms of respiratory diseases will be analyzed for mucin and protein composition. Histologic specimens obtained from the LungMAP Biorepository (BRINDL) will be probed for mRNA and protein expression of specific mucus markers. Completion of these aims will establish a new conceptual framework and provide much needed experimental evidence to study the pathogenesis, develop therapeutic approaches, and account for host microbiota influences on “early” lung health and early onset muco-obstructive lung diseases.