Non-oxidative Resistance to A. fumigatus by Alveolar Macrophages

肺泡巨噬细胞对烟曲霉的非氧化抗性

• 批准号: 7449490
• 负责人: JAMES B BURRITT
• 金额: $ 18.63万
• 依托单位: UNIVERSITY OF WISCONSIN STOUT
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-05-27 至 2011-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7449490
• 关键词: Address; Alveolar Macrophages; Animals; Antifungal Agents; Aspergillosis; Aspergillus fumigatus; Bioprobe; Breathing; Cause of Death; Cells; Conflict (Psychology); Data; Development; Environment; Event; Gene Expression; Generations; Germination; Goals; Harvest; Host Defense; Human; Immune; Immunity; Immunocompromised Host; In Vitro; Individual; Infection; Inflammatory Response; Life; Lung; Mediating; Medical; Methods; Molecular; Mouse Strains; Mus; NADPH Oxidase; Natural Immunity; Nutrient; Organism; Oxidants; Oxidases; Patients; Phagocytes; Phagocytosis; Phagolysosome; Process; Production; Protein Kinase C; Reporting; Reproduction spores; Research; Resistance; Respiratory Burst; Risk; Role; Superoxides; System; Testing; Time; Up-Regulation; Work; Zymosan; deprivation; design; fungus; in vivo; killings; microbicide; mouse model; neutrophil; particle; pathogen; public health relevance; response; therapeutic target

DESCRIPTION (provided by applicant): Infections caused by Aspergillus fumigatus are a leading cause of death in immune compromised individuals. A. fumigatus is also a threat to those lacking a functional NADPH oxidase system, a defensive oxidant-generating system of phagocytic immune cells. Alveolar macrophages (AM) are phagocytes known to be important in the early innate defense against A. fumigatus conidia, and have been reported to produce oxidants to kill engaged pathogens. However, many details about the molecular mechanisms by which AM kill A. fumigatus are not well understood. With conflicting data about the antifungal mechanisms of AM, and the role of NADPH oxidase in this process, we proposed to better define the microbicidal mechanism of AM that protects from infections by A. fumigatus. The overall hypothesis being investigated is that the AM-derived resistance to A. fumigatus conidia is mediated by NADPH oxidase-independent microbicidal mechanisms that involve nutrient sequestration, leading to conidial killing. Three aims proposed to address this goal are: 1) to compare the conidiacidal activity of AM from normal and gp91phox-/- mice that lack a functional phagocyte oxidase, using both in vitro and in vivo analyses. Reports on the role of NADPH oxidase of AM in protecting humans from IPA are conflicting, and our data do not indicate the respiratory burst in AM is necessary for a resistance to aspergillosis, as we have shown it is in neutrophils. This information will provide a better understanding of how the NADPH oxidase is applied in aspergillosis immunity. 2) to compare NADPH oxidase-dependent superoxide liberation by AM from normal C57Bl/6 and gp91phox-/- mice to describe the capabilities of oxidant production of AM in these mouse strains. Our preliminary data suggest that oxidant production in AM from normal and gp91phox-/- mice is not significantly different when triggered by oxidant-triggering stimulants, or by phagocytosis of fungal particles. This information will provide a better understanding of the capacity of oxidant generation by AM, and 3) to compare transcriptional responses of conidia exposed to AM from normal C57Bl/6 mice, to those in conidia subjected to low nutrient conditions. This aim will test whether nutrient sequestration is a conidiacidal mechanism of AM. If oxidative killing of conidia is not utilized by AM, then the use of A. fumigatus conidia as a bioprobe of the conidiacidal environment of the AM should be suggested by transcriptional responses of internalized conidia. This information will provide a better understanding of the antifungal mechanism of AM that kills A. fumigatus conidia. The long-term goal of these approaches is to identify potential therapeutic targets to augment the natural immunity that protects from infections by A. fumigatus. PUBLIC HEALTH RELEVANCE: Aspergillus fumigatus is an inhaled fungus that can infect human patients with various types if immune suppression. At this time, most individuals that become infected by this organism do not survive, despite aggressive medical management. The long- term goal of this work is to identify molecular mechanisms that enable alveolar macrophages to kill the spore-like conidial form of A. fumigatus, so that natural immunity can be augmented in those at risk.

描述（由申请人提供）：烟曲霉引起的感染是免疫受损个体死亡的主要原因。烟曲霉对那些缺乏功能性NADPH氧化酶系统的人也是一种威胁，NADPH氧化酶系统是吞噬免疫细胞的一种防御性氧化剂生成系统。肺泡巨噬细胞（AM）是一种已知的吞噬细胞，在早期对烟芽胞杆菌的先天防御中起重要作用，并且有报道称其产生氧化剂来杀死参与的病原体。然而，AM杀灭烟曲霉的分子机制的许多细节尚不清楚。由于AM的抗真菌机制和NADPH氧化酶在这一过程中的作用存在矛盾，我们提出更好地定义AM保护烟曲霉感染的杀微生物机制。目前正在研究的总体假设是，am对烟曲霉分生孢子的抗性是由不依赖于NADPH氧化酶的杀微生物机制介导的，该机制涉及营养隔离，导致分生孢子被杀死。为了实现这一目标，提出了三个目标：1)通过体外和体内分析，比较正常小鼠和缺乏功能性吞噬细胞氧化酶的gp91phox-/-小鼠AM的分生孢子活性。关于AM的NADPH氧化酶在保护人类免受IPA的作用的报道是相互矛盾的，我们的数据并没有表明AM的呼吸爆发对于抵抗曲霉病是必要的，正如我们在中性粒细胞中所显示的那样。这一信息将更好地理解NADPH氧化酶是如何应用于曲霉病免疫的。2)比较正常C57Bl/6小鼠和gp91phox-/-小鼠的AM对NADPH氧化酶依赖性超氧化物的释放，以描述这些小鼠品系AM产生氧化剂的能力。我们的初步数据表明，正常小鼠和gp91phox-/-小鼠AM中氧化剂的产生在氧化触发刺激物或真菌颗粒吞噬作用下没有显著差异。这一信息将有助于更好地了解AM产生氧化剂的能力，3)比较正常C57Bl/6小鼠暴露于AM的分生孢子与低营养条件下的分生孢子的转录反应。本研究旨在验证营养固存是否为AM的分生机制。如果AM没有利用氧化杀死分生孢子，那么利用烟曲霉分生孢子作为AM分生环境的生物探针应该是由内化分生孢子的转录反应提出的。这一信息将为AM杀灭烟曲霉分生孢子的抗真菌机制提供更好的理解。这些方法的长期目标是确定潜在的治疗靶点，以增强保护免受烟曲霉感染的天然免疫力。