Mechanisms of Effector-mediated Host Defense

效应器介导的宿主防御机制

• 批准号: 10397677
• 负责人: Stephanie Rochelle Shames
• 金额: $ 23.5万
• 依托单位: KANSAS STATE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-06-01 至 2025-04-30
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10397677
• 关键词: Address; Aerosols; Alveolar Macrophages; Animal Model; Attenuated; Bacteria; Bacterial Infections; Bacterial Proteins; Biochemistry; Cells; Cellular biology; Communicable Diseases; Cytokine Receptors; Cytosol; Data; Defense Mechanisms; Detection; Disease; Disease Outbreaks; Etiology; Event; Extravasation; Flagellin; Genetic; Genetic Techniques; Goals; Homologous Gene; Host Defense; Host Defense Mechanism; Human Activities; Image; Immune; Immune Evasion; Immune response; Immune system; Immunity; Immunologic Receptors; Immunologics; Immunology; Impairment; Infection; Infectious Agent; Inflammatory; Inhalation; Innate Immune System; Integration Host Factors; Investigation; Laboratories; Legionella; Legionella longbeachae; Legionella pneumophila; Legionnaires' Disease; Lipids; Lung; Mammals; Mediating; Methods; Modeling; Molecular; Mus; Outcome; Pathogen detection; Pathogenesis; Pathogenicity; Pathway interactions; Persons; Phagocytes; Prevalence; Proteins; Proteomics; Protozoa; Public Health; Research; Salvelinus; Signal Transduction; System; Testing; Therapeutic; Therapeutic Intervention; Type IV Secretion System Pathway; United States National Institutes of Health; Virulence; Virulent; Work; Zoonoses; attenuation; combat; contaminated water; cytokine; disorder prevention; experimental study; fitness; global health; human pathogen; immune activation; immune clearance; innovation; insight; lung pathogen; macrophage; mouse model; novel; novel therapeutic intervention; pathogen; pathogenic bacteria; pathogenic microbe; prevent; pulmonary function; response; targeted treatment; therapy development; tool; transmission process; treatment strategy

Project Summary: Emerging and zoonotic infectious diseases (EZIDs) cause global health devastation and are increasing in prev- alence due to human activity and other factors that facilitate disease spread. Often, the etiological agents of EZIDs are difficult to study due to lack of established tools and genetic systems to perform hypothesis-driven research. The objective of this proposal is to use bacteria of the genus Legionella as model pathogens to char- acterize host defense mechanisms applicable to EZIDs. Legionella species are natural pathogens of protozoa and accidental human pathogens that can cause disease upon inhalation of contaminated aerosols and subse- quent bacterial replication within alveolar macrophages. As transmission between mammals is rare, Legionella has not acquired sophisticated immune evasion mechanisms, and are, therefore, excellent model pathogens to reveal host immune defense mechanisms. Legionella replication within phagocytic cells is facilitated by a Dot/Icm type IV secretion system (T4SS), which translocates a repertoire of bacterial proteins called effectors into in- fected host cells. Although effector translocation is required for intracellular replication, effector functions can also impair Legionella fitness in mammals. The overall objective is to elucidate mechanisms by which effector function contributes to pathogen clearance by the innate immune system and determine whether these can be used to enhance defense against other pathogens. The central hypothesis is that LegC4 interacts with host factors to enhance cytokine-mediated host defense. To test the central hypothesis, we will test the following specific aims. Aim 1 is to define the mechanism of LegC4-mediated attenuation of bacterial replication in mac- rophages; Aim 2 is to identify host factors modulated by LegC4; and Aim 3 is to determine if LegC4 is able to protect mice from infection with a highly virulent Legionella species that does not naturally encode LegC4. Through this work, we will elucidate the function of the effector LegC4 and further determine if LegC4 is sufficient to promote host defense against non-pneumophila pathogens. To address these questions, we will use cell biology, imaging, immunology, biochemistry, genetic techniques and animal models. The proposed project is innovative and has potential to positively impact public health. Mechanisms by which the mammalian immune system detects and eradicates pathogens can be harnessed to treat and prevent infectious diseases. The ben- efits of studying innate immune activation by effectors are (1) previously uncharacterized pathogen detection strategies may be identified and targeted for therapeutic intervention; and (2) the effectors can be used as ther- apeutics to enhance immune clearance of pathogenic microbes. Ultimately, the work will culminate in enhanced understanding of host defense strategies and provide the means to develop therapeutics that will be effective against a broad range of infectious agents. This is especially important to limit disease outbreaks and decrease the global health burden associated with EZIDs. This work will provide preliminary data required for a successful R01 application to investigate mechanisms of effector-mediated host immune restriction of bacterial pathogens.

项目概要： 新出现的人畜共患传染病（EZID）造成全球健康破坏，并且在前几年不断增加。 由于人类活动和其他促进疾病传播的因素而造成的疾病。通常， 由于缺乏既定的工具和遗传系统来执行假设驱动，EZID很难研究 research.本提案的目的是使用军团菌属的细菌作为模式病原体， 适用于EZID的入侵主机防御机制。军团菌属是原生动物的天然病原体 以及在吸入受污染的气溶胶后可能导致疾病的意外人类病原体， 肺泡巨噬细胞内的细菌复制。由于哺乳动物之间的传播是罕见的， 没有获得复杂的免疫逃避机制，因此是极好的模式病原体， 揭示宿主免疫防御机制。军团菌在吞噬细胞内的复制由Dot/Icm促进 IV型分泌系统（T4 SS），它将一系列称为效应子的细菌蛋白质易位到体内， 感染的宿主细胞。尽管效应子易位是细胞内复制所必需的，但效应子功能可以 也会削弱军团菌在哺乳动物中的适应性。总体目标是阐明效应子 功能有助于先天免疫系统清除病原体，并决定这些功能是否可以 用于增强对其他病原体的防御。核心假设是LegC 4与宿主相互作用 因子，以增强甜菜碱介导的宿主防御。为了检验中心假设，我们将检验以下内容 明确的目标。目的1是确定在mac中LegC 4介导的细菌复制衰减的机制， 目的2是鉴定由LegC 4调节的宿主因子;目的3是确定LegC 4是否能够 保护小鼠免受不天然编码LegC 4的高毒性军团菌属的感染。 通过这项工作，我们将阐明效应子LegC 4的功能，并进一步确定LegC 4是否足够 以促进宿主防御非嗜肺病原体。为了解决这些问题，我们将使用cell 生物学、成像学、免疫学、生物化学、遗传技术和动物模型。拟建项目 具有创新性，有可能对公共卫生产生积极影响。哺乳动物的免疫机制 系统检测和根除病原体可以用来治疗和预防传染病。本- 研究效应子对先天免疫激活的作用有以下几点：（1）以前未鉴定的病原体检测 可以确定治疗干预的策略和靶向策略;以及（2）效应物可以用作治疗药物。 增强病原微生物的免疫清除的药剂。最终，这项工作将在增强 了解宿主防御策略，并提供开发有效治疗方法的手段 对抗各种各样的传染源这对于限制疾病爆发和减少 与EZID相关的全球健康负担。这项工作将提供成功的研究所需的初步数据。 R 01在研究细菌病原体的效应子介导的宿主免疫限制机制中的应用。