Antifungal Immunity and the Mechanism of Fungal Programmed Cell Death

抗真菌免疫和真菌程序性细胞死亡机制

基本信息

批准号：
10538624
负责人：
Robert Andrew Cramer
金额：
$ 65.3万
依托单位：
SLOAN-KETTERING INST CAN RESEARCH
依托单位国家：
美国
项目类别：
财政年份：
2019
资助国家：
美国
起止时间：
2019-01-22 至 2024-12-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/10538624
关键词：
Antifungal Agents Apoptosis Apoptosis Inhibitor Apoptosis Regulation Gene Apoptotic Applications Grants Aspergillosis Aspergillus fumigatus Aspergillus nidulans Baculoviruses Biochemical Biochemistry Biological Models Candida albicans Candidiasis Cartoons Caspase Cell Death Cell Death Induction Cells Collaborations Complement DNA Fragmentation Data Defect Development Disease Disease Outcome Enzymes Essential Genes Etiology Eukaryota Family Fungal Genes Fungal Proteins Fungal Spores Genetic Genetic study Germination Goals Histones Homologous Gene Host Defense Human Hyphae Immune Immunity Immunologic Surveillance Immunologics Immunology Induction of Apoptosis Inhalation Innate Immune System Knowledge Laboratories Lung Mediating Modeling Molds Myelogenous NADPH Oxidase Oxidative Stress Pathogenesis Pathway interactions Patient-Focused Outcomes Patients Phagocytes Pharmacology Study Physiology Play Pneumonia Post-Translational Regulation Predisposition Process Proteins Regulation Reporter Reporting Reproduction spores Research Personnel Resistance Respiratory Burst Role Stress System Tertiary Protein Structure Testing Therapeutic Tissues Virulence Visualization Work experience fungal genetics immune checkpoint immune function improved in vivo innovation insight member new therapeutic target novel novel therapeutic intervention pathogenic fungus pharmacologic predictive modeling prevent respiratory response

项目摘要

PROJECT SUMMARY Humans inhale fungal conidia (i.e, vegetative spores) on a daily basis. The ability of the respiratory innate immune system to prevent germination of inhaled conidia into tissue-invasive hyphae represents a critical immunologic checkpoint. Using Aspergillus fumigatus, the most common etiologic agent of invasive aspergillosis, as a model system for human fungal pathogens, we discovered that conidia undergo programmed cell death with apoptosis-like features during interactions with innate immune cells. This finding was facilitated by a novel fluorescent reporter of fungal physiology that enables visualization and quantitation of fungal apoptosis markers, including histone degradation, caspase activation, and DNA fragmentation. Our work demonstrates that A. fumigatus conidia express an essential and druggable anti-apoptotic protein, termed Bir1, that counters host induction of apoptosis-like programmed cell death by the action of phagocyte NADPH oxidase. Genetic and pharmacologic studies demonstrate that Bir1 expression and activity underlie conidial susceptibility to host apoptosis-like programmed cell death, and in turn, host susceptibility to invasive aspergillosis. These findings indicate that mammalian fungal immune surveillance exploits a fungal apoptosis- like programmed cell death pathway to maintain barrier immunity in the lung. In this collaborative proposal with two co-investigators, we seek to determine the mechanism through which Bir1 regulates anti-apoptotic activity during fungal-host cell encounters. Our preliminary data support a model in which Bir1 exerts anti-apoptotic activity via two conserved BIR domains, underlies post-translational regulation in response to pro-apoptotic stress, regulates candidate fungal caspase-like enzymes as apoptosis effectors, and demonstrates functional conservation across human pathogenic fungi. Based on these observations, our model predicts that fungal apoptosis-like programmed cell death is a general feature of fungal-host cell encounters and central to the establishment of invasive fungal disease. We explore this model in the following aims: (1) define the functional domains and post-translational regulation of Bir1 critical for resistance to host induction of apoptosis-like programmed cell death, (2) define the mechanism of Bir1- mediated resistance to host induction of apoptosis-like programmed cell death, with an emphasis on regulation of a candidate fungal caspase-like activity, and (3) define the role of apoptosis-like programmed cell death and Bir1 homologs following Aspergillus nidulans and Candida albicans challenge. The proposed studies are significant and innovative because they identify a novel mechanism of immune surveillance and demonstrate that higher eukaryotes can exploit programmed cell death in lower eukaryotes for the purpose of sterilizing immunity. This work will provide a mechanistic understanding of Bir1 function in regulating host-fungal encounters. Knowledge gained from these studies will inform strategies that target fungal Bir1 homologs and exploit fungal apoptosis-like programmed cell death for therapeutic gain.

项目摘要人类每天吸入真菌分生孢子（即营养孢子）。呼吸与先天性的能力免疫系统防止吸入的分生孢子在组织侵入性菌丝中发芽是关键的免疫学检查点。使用曲霉富马图斯，这是最常见的侵入性病因学剂曲霉病，作为人类真菌病原体的模型系统，我们发现分生孢子经历在与先天免疫细胞相互作用期间，具有类似细胞凋亡特征的程序性细胞死亡。这个发现真菌生理学的新型荧光记者促进了可视化和定量真菌细胞凋亡标记物，包括组蛋白降解，caspase激活和DNA碎片。我们的工作表明，烟曲霉分生孢子表达了一种必不可少的抗凋亡蛋白，称为BIR1，该反理通过吞噬细胞的作用来对抗凋亡样细胞死亡的宿主诱导 NADPH氧化酶。遗传学和药理学研究表明，BIR1表达和活性是基础分生孢子易感性宿主凋亡样式细胞死亡，而宿主对侵入性的敏感性曲霉病。这些发现表明，哺乳动物真菌免疫监测利用了真菌凋亡 - 就像程序性细胞死亡通路一样，以维持肺中的屏障免疫。在与两个共同评估者的合作提议中，我们试图确定 BIR1调节真菌宿主遇到的抗凋亡活性。我们的初步数据支持模型其中BIR1通过两个保守的BIR结构域发挥抗凋亡活性，这是翻译后的基础调节促凋亡应激，调节候选真菌caspase样酶为凋亡效应子，并在人类致病真菌中展示功能保护。基于这些观察结果，我们的模型预测，真菌凋亡样式细胞死亡是真菌 - 宿主细胞遇到的，是建立侵入性真菌疾病的中心。我们探索这个模型在以下目的中：（1）定义BIR1的功能域和翻译后调节抗宿主诱导凋亡样细胞死亡的抗性，（2）定义BIR1-的机制介导的宿主诱导类细胞凋亡样细胞死亡的抗性，重点是调节候选真菌caspase样活性，（3）定义凋亡样细胞死亡和 BIR1同源物在曲霉菌和白色念珠菌挑战之后。拟议的研究是重要而创新的，因为它们确定了一种新颖的免疫监视机制并证明较高的真核生物可以利用较低真核生物中的程序性细胞死亡进行消毒免疫。这项工作将对BIR1功能的机械理解在调节宿主 - 宿主方面相遇。从这些研究中获得的知识将告知针对真菌BIR1同源物和的策略利用真菌细胞凋亡样细胞死亡，以获得治疗性增加。