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: 8531849
• 负责人: Jordi B Torrelles
• 金额: $ 35.84万
• 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/8531849
• 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.结核病通过空气传播，杆菌沉积在肺的肺泡腔中。传统观点认为M.结核病在初始感染过程中有些“静止”，不诱导免疫应答，并且它被非活化的肺泡巨噬细胞（AM）摄取，所述非活化的肺泡巨噬细胞（AM）充当感染的重要储库。然而，我们假设在肺泡腔M沉积后。肺结核进入动态阶段，在那里它遇到肺表面活性剂，该表面活性剂含有改变M.结核菌细胞壁这些水解酶释放生物活性M。结核病碎片进入局部环境，刺激肺泡内的各种肺细胞，改变肺微环境，从而改变感染的结果。我们最近发表了人肺表面活性物质中存在的水解酶显著改变了M.结核病在感染期间将细胞壁碎片释放到肺环境中。由于这些M。通过细胞壁修饰，杆菌与人巨噬细胞的结合显著减少，随后吞噬体-溶酶体融合增加，这转化为M. TB在这些细胞内的细胞内存活和炎性细胞因子产生的增加导致感染的更好控制。除了改造M。tb细胞壁，我们推测M.肺结核细胞壁对人肺表面活性物质水解酶的反应所释放的碎片将影响感染结果。我们的初步数据表明，释放的M。在与肺表面活性水解酶接触时产生的TB细胞壁碎片能够激活原代人肺泡隔室细胞。此外，暴露于这些片段的人巨噬细胞能够更好地控制M。肺结核感染。这些发现为肺环境对M.结核-宿主相互作用在感染的不同阶段，如在感染的初始阶段;从裂解的巨噬细胞释放后;当M.肺结核是在肺腔中的细胞外发现的。在所有这些阶段，M。结核病与含有水解酶的细胞外宿主分泌物密切接触，水解酶将改变结核病的细胞壁并释放碎片。为了解决我们的假设，我们建议：i）确定M的结构。tb细胞壁片段暴露于人肺泡水解酶后释放; ii）确定M.表面活性剂水解酶产生的细胞壁修饰和释放的细胞壁碎片影响M.使用人原代肺泡隔室细胞进行体外结核感染;和iii）确定M.表面活性剂水解酶产生的细胞壁修饰和释放的细胞壁碎片影响M.体内结核感染。该应用在研究肺表面活性物质和M之间重要而鲜为人知的关系方面是创新和独特的。结核感染和挑战我们现有的知识，宿主-病原体相互作用，已阐明在体外。肺内环境在M.在感染过程中遇到的结核病还没有得到充分研究，关于它对结核病的贡献也知之甚少。结核病发病机制。