The impact of mucociliary clearance on Mycobacterium tuberculosis pathogenesis

项目概要/摘要。2021年，超过100万人死于结核病。目前的治疗方法是 时间长，成本高，而且经常引起严重的副作用，但目前的疫苗在100多个国家没有得到改进， 年提高对影响肺结核发病机制的宿主因素的认识， 改善结核病控制和个体间的传播。在进入肺泡巨噬细胞之前， 遇到呼吸道粘蛋白。粘蛋白是糖基化的大分子，包括第一道防线 对抗病原体呼吸道粘蛋白MUC 5 B和MUC 5AC通过粘膜纤毛保护肺免受病原体的侵害 清除，直接抑制抗微生物生长和改变巨噬细胞信号传导。然而， 这些大分子如何影响结核病的易感性和严重性。在这个试点赠款中，我们将评估 呼吸道粘蛋白如何影响结核分枝杆菌发病机制的人类遗传学研究， 其作用机制通过重现Muc 5 b或Muc 5ac不足、缺乏或 过度表达我们的长期目标是确定在肺内有效杀死结核分枝杆菌的策略， 相关候选Mtb疫苗的粘膜递送。这项补助金的目的是描述 两种最常见的呼吸道粘蛋白MUC 5 B和MUC 5AC影响Mtb的机制 易感性和严重性。这项研究的基本原理是，呼吸道粘蛋白是 对粘膜纤毛清除必不可少，支持肺中大量的细胞外抗菌肽和蛋白质， 并包覆病原体以改变其在肺中的致病性。我们的初步数据显示， MUC 5 B启动子区的遗传变异与肺结核和MUC 5 B mRNA相关 肺中的表达，而MUC 5AC基因区域的变异与结核性脑膜炎死亡率相关 和MUC 5AC mRNA表达。中心假设是MUC 5 B和MUC 5AC是MUC 5 B和MUC 5AC的物理屏障。 感染且还调节巨噬细胞功能和全身免疫稳态以使TB疾病恶化 严重性。在这项资助中，我们将通过实现以下具体目标来测试这一假设：1）我们将定义 调节肺中MUC 5 B和MUC 5AC基因表达的功能性SNP，全身免疫应答 结核性脑膜炎，以及越南队列中结核病的易感性和严重性。2)康贝特人将以 Muc 5 b和Muc 5ac缺陷、敲除和过表达影响临床和 使用感染Mtb的遗传修饰小鼠对Mtb的免疫应答。这一贡献意义重大 因为粘蛋白代表抗Mtb感染的第一道防线，但它们在Mtb发病机制中的作用是 未知拟议的工作是创新的，因为我们将调查的机制和影响，一个已知的 结核病易感基因使用创新的小鼠疾病模型，结合结核病的遗传队列 易感性这些研究将提供证据表明，结核分枝杆菌宿主防御开始前巨噬细胞感染 并为免疫微环境对结核分枝杆菌结果的作用提供线索。

Project Summary/Abstract. Over one million people died from tuberculosis in 2021. Current treatments are long, costly, and often induce severe adverse effects, but the current vaccine has not been improved in over 100 years. Improved understanding of the host factors that influence Mtb pathogenesis in the lung may dramatically improve control and transmission of Mtb between individuals. Before entering the alveolar macrophage, Mtb encounters respiratory mucins. Mucins are glycosylated macromolecules that encompass the first line of defense against pathogens. Respiratory mucins MUC5B and MUC5AC protect the lung from pathogens via mucociliary clearance, directly inhibiting antimicrobial growth, and altering macrophage signaling. However, little is known about how these macromolecules influence Mtb susceptibility and severity. In this pilot grant, we will evaluate how respiratory mucins impact Mtb pathogenesis using human genetic studies, combined with interrogation of their mechanism of action via small animal models recapitulating Muc5b or Muc5ac insufficiency, deficiency, or overexpression. Our long-term goal is to identify strategies for effective Mtb killing within the lung and improve mucosal delivery of relevant candidate Mtb vaccines. The objective of this grant is to characterize the mechanisms by which MUC5B and MUC5AC, the two commonest respiratory mucins, influence Mtb susceptibility and severity in human populations. The rationale for this study is that respiratory mucins are essential for mucociliary clearance, support a host of extracellular antimicrobial peptides and proteins in the lung, and coats pathogens to alter their pathogenicity in the lung. Our preliminary data demonstrates that common genetic variants in the MUC5B promoter region are associated with pulmonary TB and MUC5B mRNA expression in the lung, while variation in the MUC5AC gene region is associated with TB meningitis mortality and MUC5AC mRNA expression. The central hypothesis is that MUC5B and MUC5AC are physical barriers to infection and also modulate macrophage function and systemic immune homeostasis to worsen TB disease severity. In this grant, we will test this hypothesis by achieving the following specific aims: 1) We will define the functional SNPs that regulate MUC5B and MUC5AC gene expression in the lung, systemic immune responses to TB meningitis, and susceptibility to and severity of TB in a Vietnamese cohort. 2) We will determine the mechanism by which Muc5b and Muc5ac deficiency, knockout, and overexpression influence clinical and immune responses to Mtb using genetically modified mice infected with Mtb. This contribution is significant because mucins represent the first line of defense against Mtb infection, but their role in Mtb pathogenesis is unknown. The proposed work is innovative because we will investigate the mechanisms and effects of a known TB susceptibility gene using innovative mouse models of disease, combined with the genetic cohorts of TB susceptibility. These studies will provide evidence that Mtb host defense begins prior to macrophage infection and provide clues toward the role of the immune microenvironment on Mtb outcomes.