The role of TLR9 on Aspergillus fumigatus phagosomes

TLR9对烟曲霉吞噬体的作用

• 批准号: 8704869
• 负责人: Jatin M Vyas
• 金额: $ 41.72万
• 依托单位: MASSACHUSETTS GENERAL HOSPITAL
• 依托单位国家: 美国
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-07-23 至 2017-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8704869
• 关键词: Antigens; Aspergillosis; Aspergillus fumigatus; Biological Process; Breathing; C Type Lectin Receptors; Carbohydrates; Cell Wall; Cells; Chitin; Confocal Microscopy; DNA; Development; Distal; Endothelial Cells; Environment; Glucans; Hematopoietic stem cells; Host Defense; Hydrolase; Hyphae; Image; Immune; Immune response; Immune system; Immunocompromised Host; Industrial fungicide; Infection; Inflammatory; Inflammatory Response; Knowledge; Laboratories; Lead; Learning; Life; Ligands; Link; Lung; Mechanics; Mediating; Molds; Molecular; Mus; Organ Transplantation; Organism; Pathogenesis; Pathway interactions; Patients; Pattern; Phagocytosis; Phagosomes; Polysaccharides; Polystyrenes; Prevention; Production; Protein Dynamics; Proteins; Receptor Signaling; Recruitment Activity; Regulation; Reproduction spores; Rest; Role; Shapes; Signal Transduction; Solid; Stem cell transplant; Surface; Swelling; T cell response; TLR2 gene; TLR4 gene; Therapeutic; Time; Toll-Like Receptor 2; Toll-like receptors; Viral; Virulence; Work; adaptive immunity; asexual; cellular imaging; cytokine; dectin 1; extracellular; fungus; galactomannan; imaging modality; insight; macrophage; mutant; novel; optical traps; outcome forecast; particle; pathogen; public health relevance; receptor; response; trafficking; uptake

DESCRIPTION (provided by applicant): Aspergillus fumigatus is a saprophytic filamentous fungus whose asexual spores called conidia are widespread in the environment, acquired through inhalation and small enough to reach the distal airways. Approximately 10% of patients with hematopoietic stem cell transplants or solid organ transplants will develop invasive aspergillosis, a life-threatening infection. Despite the development of effective fungicidal agents the prognosis for disseminated infection is quite poor, indicating that knowledge of the rules that govern the host defense against A. fumigatus is critical for development of new prevention and therapeutic strategies. Evidence for the importance of innate immune mechanisms in fungal defense is mounting. The fungal ¿-1,3 glucan receptor Dectin1 is essential in pulmonary defense against A. fumigatus and collaborates with TLR2 and TLR4 in providing critical immune signals that coordinate cytokine secretion and development of the adaptive immunity. When challenged with A.fumigatus, TLR9-deficient mice are incapable of mounting an antigen-specific T cell response, directly implicating the involvement of TLR9 in the host defense against this fungal pathogen. However, the cell biological processes underlying TLR9-mediated A.fumigatus immune responses are still largely unresolved. In order to understand better the role of TLR9 in host defense against A. fumigatus, we have made the following key observations that are the rationale for our proposed work: 1) the presence of A. fumigatus phagosomes in macrophages results in a dramatic change of the subcellular distribution of TLR9 from the ER to a bright, ring-shaped compartment around the fungus 2) macrophages lacking Dectin-1 fail to recruit TLR9, indicating that the presence of Dectin-1 is required for proper TLR9 trafficking to the fungal phagosome 3) polystyrene beads with purified, fungal-derived ¿-1,3-glucan attached covalently to the surface can mimic fungal particles during phagocytosis. We hypothesize that a component of the A. fumigatus cell wall mediates TLR9 recruitment and that Dectin-1 controls the trafficking of TLR9 to the fungal phagosome. We propose to: 1) determine the role of Dectin-1 in TLR9 recruitment to A. fumigatus phagosomes in APCs. 2) determine the molecular requirement for TLR9 recruitment to phagosomes containing fungal-like particles. 3) dissect the differences in immunological responses to RC, SC, H, ¿-1,3 glucan and galactomannan beads by macrophages using optical trap. We will apply advanced imaging modalities including live cell imaging using spinning disk confocal microscopy and optical trapping to control spatial interactions between host cell and pathogen. Knowledge gained regarding the mechanism of regulation of TLR9 trafficking to fungal phagosomes will be important in furthering our understanding of the innate immune response to A. fumigatus, and could lead to novel insights on how to modulate the host defense against this deadly pathogen.

描述（由申请方提供）：烟曲霉是一种嗜盐丝状真菌，其称为分生孢子的无性孢子在环境中广泛分布，通过吸入获得，并且足够小以到达远端气道。大约10%的造血干细胞移植或实体器官移植患者会发生侵袭性曲霉病，这是一种危及生命的感染。尽管开发了有效的杀真菌剂，但传播性感染的预后相当差，这表明对规则的了解， 控制宿主对A的防御。烟曲霉对开发新的预防和治疗策略至关重要。先天免疫机制在真菌防御中的重要性的证据越来越多。真菌<$-1，3葡聚糖受体Dectin 1在肺防御A.在烟曲霉中表达，并与TLR 2和TLR 4合作提供协调细胞因子分泌和适应性免疫发展的关键免疫信号。当用烟曲霉攻击时，TLR 9缺陷型小鼠不能产生抗原特异性T细胞应答，直接暗示TLR 9参与宿主对这种真菌病原体的防御。然而，TLR 9介导的烟曲霉免疫应答背后的细胞生物学过程仍然在很大程度上未得到解决。为了更好地了解TLR 9在宿主防御A.通过对烟曲霉（A. fumigatus）的研究，我们发现了以下关键的观察结果，这些观察结果是我们所提出的工作的基本原理：1）A. 2）缺乏Dectin-1的巨噬细胞不能募集TLR 9，表明Dectin-1的存在是正确的TLR 9运输到真菌吞噬体所必需的; 3）具有纯化的真菌衍生的聚苯乙烯珠，共价连接到表面的β-1，3-葡聚糖在吞噬作用期间可以模拟真菌颗粒。我们假设A. Fumigatus细胞壁介导TLR 9募集，Dectin-1控制TLR 9向真菌吞噬体的运输。1）确定Dectin-1在TLR 9向A. APC中的烟曲霉吞噬体。2)确定TLR 9募集到含有真菌样颗粒的吞噬体的分子要求。3)利用光学陷阱分析巨噬细胞对RC、SC、H、<$-1，3葡聚糖和半乳甘露聚糖珠的免疫应答的差异。我们将应用先进的成像方式，包括活细胞成像，使用旋转盘共聚焦显微镜和光学捕获来控制宿主细胞和病原体之间的空间相互作用。关于TLR 9运输到真菌吞噬体的调节机制的知识对于进一步理解对A.烟曲霉，并可能导致新的见解如何调节宿主防御这种致命的病原体。