Function of human lung mucosal hydrolases during M. tuberculosis infection

结核分枝杆菌感染期间人肺粘膜水解酶的功能

• 批准号: 8702074
• 负责人: Jordi B Torrelles
• 金额: $ 38.13万
• 依托单位: OHIO STATE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-08-20 至 2016-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8702074
• 关键词: Acid Phosphatase; Address; Alkaline Phosphatase; Alveolar; Alveolar Macrophages; Alveolus; Bacillus (bacterium); Biochemical; Cell Communication; Cell Wall; Cells; Cytolysis; Data; Deposition; Environment; Enzymes; Epithelial Cells; Exposure to; Goals; Human; Hydrolase; Immune response; In Vitro; Infection; Infection Control; Inflammatory; Knowledge; Lead; Lung; Lysosomes; Modeling; Modification; Mus; Mycobacterium tuberculosis; Outcome; Pathogenesis; Persons; Phagosomes; Phase; Production; Property; Publishing; Pulmonary Surfactants; Role; Staging; Structure; TNF gene; Techniques; Translating; Tuberculosis; antimicrobial; carboxylesterase; cell envelope; cytokine; extracellular; immune function; in vivo; innovation; killings; macrophage; neutrophil; pathogen; public health relevance; response; surfactant; transmission process

DESCRIPTION (provided by applicant): When Mycobacterium tuberculosis (M. tb) infection occurs by airborne transmission, bacilli are deposited in the alveolar spaces of the lungs. The traditional view is that M. tb is somewhat "static" during initial infection, does not induce an immune response, and it is taken up by non-activated alveolar macrophages (AMs) that serve as an important reservoir for infection. However, we hypothesize that upon deposition in the alveolar space M. tb enters a dynamic phase where it encounters pulmonary surfactant that contains homeostatic and antimicrobial enzymes (hydrolases) which alter the M. tb cell wall. These hydrolases release biologically active M. tb fragments into the local milieu and stimulate a variety of lung cells within the alveoli that changes the pulmonary microenvironment, and thus the outcome of infection. We recently published that hydrolases present in the human lung surfactant dramatically alter the cell envelope of M. tb during infection releasing cell wall fragments into the lung milieu. As a result of these M. tb cell wall modifications, bacilli had a significant decrease in association with human macrophages followed by an increase in phagosome-lysosome fusion, which translated to a significant decrease in M. tb intracellular survival within these cells and an increase in inflammatory cytokine production leading to better control of infection. In addition to remodeling of the M. tb cell wall by host lung hydrolases, we hypothesize that M. tb cell wall fragments released in response to human lung surfactant hydrolases will influence the infection outcome. Our preliminary data show that released M. tb cell wall fragments generated upon contact with lung surfactant hydrolases are capable of activating primary human alveolar compartment cells. Moreover, human macrophages exposed to these fragments are better able to control M. tb infection. These findings add a new concept to the contribution of the lung environment to M. tb-host interactions at different stages of infection such as at the initial stage of infection; following release from lysed macrophages; and when M. tb is found extracellularly within lung cavities. In all of these stages, M. tb is in intimte contact with extracellular host secretions containing hydrolases that will alter its cell wall and release fragments. To address our hypothesis we propose to: i) Determine the structure of M. tb cell wall fragments released following exposure to the human alveolar hydrolases; ii) Determine how M. tb cell wall modifications and released cell wall fragments generated by surfactant hydrolases influence the establishment of M. tb infection in vitro using human primary alveolar compartment cells; and iii) Determine how M. tb cell wall modifications and released cell wall fragments generated by surfactant hydrolases influence the course of M. tb infection in vivo. This application is innovative and unique in examining an important and little known relationship between lung surfactant and M. tb infection and challenges our existing knowledge of host-pathogen interactions that have been elucidated in vitro. The role of the lung environment that M. tb encounters during infection is understudied and very little is known about its contribution t M. tb pathogenesis.

描述（由申请人提供）：当结核分枝杆菌（M.tb）通过空气传播感染时，杆菌沉积在肺部的肺泡腔中。传统观点认为，结核分枝杆菌在初始感染过程中有些“静态”，不会引起免疫反应，并且被作为重要感染储存库的非活化肺泡巨噬细胞（AM）吸收。然而，我们假设结核分枝杆菌在肺泡腔沉积后进入动态阶段，在此阶段它遇到含有稳态和抗菌酶（水解酶）的肺表面活性剂，从而改变结核分枝杆菌细胞壁。这些水解酶将具有生物活性的结核分枝杆菌片段释放到局部环境中，并刺激肺泡内的各种肺细胞，从而改变肺部微环境，从而改变感染的结果。我们最近发表了人类肺表面活性剂中存在的水解酶在感染过程中显着改变结核分枝杆菌的细胞包膜，将细胞壁碎片释放到肺环境中。由于这些结核分枝杆菌细胞壁修饰，杆菌与人类巨噬细胞的关联显着减少，随后吞噬体-溶酶体融合增加，这转化为结核分枝杆菌在这些细胞内的胞内存活率显着下降，并增加炎症细胞因子的产生，从而更好地控制感染。除了宿主肺水解酶对结核分枝杆菌细胞壁的重塑之外，我们假设响应人肺表面活性剂水解酶而释放的结核分枝杆菌细胞壁碎片也会影响感染结果。我们的初步数据表明，与肺表面活性剂水解酶接触时产生的释放的结核分枝杆菌细胞壁碎片能够激活原代人肺泡室细胞。此外，接触这些碎片的人类巨噬细胞能够更好地控制结核分枝杆菌感染。这些发现为肺环境在感染的不同阶段（例如感染的初始阶段）对结核分枝杆菌与宿主相互作用的贡献增加了一个新概念；从裂解的巨噬细胞释放后；当在肺腔内的细胞外发现结核分枝杆菌时。在所有这些阶段中，结核分枝杆菌与含有水解酶的细胞外宿主分泌物密切接触，水解酶将改变其细胞壁并释放片段。为了解决我们的假设，我们建议： i) 确定暴露于人类肺泡水解酶后释放的结核分枝杆菌细胞壁碎片的结构； ii) 使用人原代肺泡隔室细胞确定结核分枝杆菌细胞壁修饰和表面活性剂水解酶产生的释放细胞壁碎片如何影响体外结核分枝杆菌感染的建立； iii)确定结核分枝杆菌细胞壁修饰和表面活性剂水解酶产生的释放细胞壁碎片如何影响体内结核分枝杆菌感染的过程。该应用在检查肺表面活性物质与结核分枝杆菌感染之间重要且鲜为人知的关系方面具有创新性和独特性，并挑战了我们对体外已阐明的宿主与病原体相互作用的现有知识。结核分枝杆菌在感染过程中遇到的肺部环境的作用尚未得到充分研究，并且对其对结核分枝杆菌发病机制的贡献知之甚少。