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: 8295651
• 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/8295651
• 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; 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. PUBLIC HEALTH RELEVANCE: One third of the world is infected with Mycobacterium tuberculosis (M. tb) killing one person worldwide every 14 seconds. This application will determine how mucosal degradative enzymes of the human lung surfactant alter the cell wall of M. tb influencing the immune response of the host and impacting the course of M. tb infection.

描述（由申请人提供）：当结核分枝杆菌（M. TB）感染是通过空气传播发生的时，杆菌沉积在肺的肺泡空间中。传统观点是，M。TB在初始感染过程中有些“静态”，不会诱导免疫反应，并且它被非激活的肺泡巨噬细胞（AMS）所吸收，这些肺泡巨噬细胞（AMS）是感染的重要储层。然而，我们假设在肺泡空间中沉积时，M。TB进入一个动态相，在该相中遇到肺表面活性剂，其中包含稳态和抗菌酶（水解酶），改变了M. TB细胞壁。这些水解酶释放出具有生物活性的M. TB片段到局部环境中，并刺激肺泡内的各种肺细胞，从而改变了肺微环境，从而改变了感染的结果。我们最近发表了，存在于人肺表面活性剂中的水解酶在感染中急剧改变了M. Tb的细胞包膜，从而释放出细胞壁碎片到肺部环境中。由于这些M. TB细胞壁的修饰，杆菌与人类巨噬细胞的相关性显着降低，然后增加了吞噬体 - 溶酶体融合融合，这转化为M. TB的细胞内生存率显着降低，并增加了炎症细胞因子产生的增加，从而可以更好地控制感染。除了通过宿主肺水解酶对M. TB细胞壁进行重塑外，我们假设M. TB细胞壁碎片响应于人类肺表面活性剂水解酶会影响感染结果。我们的初步数据表明，在与肺表面活性剂水解酶接触后产生的M. TB细胞壁碎片能够激活原代人肺泡室细胞。此外，暴露于这些碎片的人类巨噬细胞可以更好地控制M. TB感染。这些发现为在感染的不同阶段（例如在感染的初始阶段）在肺部环境中对肺部环境的贡献增加了一个新概念；从裂解巨噬细胞释放后；当在肺部腔内发现细胞内M. TB时。在所有这些阶段中，M。TB与含有会改变其细胞壁并释放片段的水解酶的细胞外宿主分泌物接触。为了解决我们的假设，我们建议：i）确定暴露于人牙槽水解酶后释放的M. TB细胞壁碎片的结构； ii）确定M. TB细胞壁的修饰和释放由表面活性剂水解酶产生的细胞壁碎片如何使用人类原发性肺泡室细胞在体外影响M. TB感染的建立； iii）确定M. TB细胞壁修饰和释放由表面活性剂水解酶产生的细胞壁碎片如何影响体内M. TB感染的过程。该应用在研究肺表面活性剂和M. TB感染之间的重要且鲜为人知的关系方面具有创新性和独特性，并挑战了我们现有的对宿主 - 病原体相互作用的知识，这些知识已阐明了体外。 M. TB在感染过程中遇到的肺部环境的作用被研究研究了，对其贡献t M. TB发病机理知之甚少。 公共卫生相关性：世界三分之一感染了结核分枝杆菌（M. TB），每14秒在全球杀死一个人。该应用将确定人肺表面活性剂的粘膜降解酶如何改变M. TB的细胞壁影响宿主的免疫反应并影响M. TB感染的过程。