Genetic and mechanistic analysis of carbon dioxide tolerance in Cryptococcus pathogenesis

隐球菌发病机制中二氧化碳耐受性的遗传和机制分析

基本信息

批准号：
10335205
负责人：
Damian J Krysan
金额：
$ 66.35万
依托单位：
UNIVERSITY OF IOWA
依托单位国家：
美国
项目类别：
财政年份：
2020
资助国家：
美国
起止时间：
2020-02-18 至 2025-01-31
项目状态：
未结题

来源：
https://reporter.nih.gov/project-details/10335205
关键词：
AIDS/HIV problem Affect Air Anabolism Antineoplastic Agents Biological Carbon Carbon Dioxide Cessation of life Clinical Cryptococcal Meningitis Cryptococcus Cryptococcus neoformans Data Disease Drug Targeting Environment Event Evolution Future Gene Expression Profile Genes Genetic Genetic Polymorphism Genetic Screening Genetic Transcription Genomic approach Genomics Genotype Glycolysis Goals Growth HIV antiretroviral HIV diagnosis HIV therapy High temperature of physical object Homeostasis Human In Vitro Incidence Infection Lung Meningoencephalitis Metabolism Minority Modeling Molecular Molecular Target Mus Mutation Opportunistic Infections Outcome Pathogenesis Pathway interactions Patients Persons Phenotype Positioning Attribute Property Publishing Quantitative Trait Loci Resource-limited setting Role Sentinel Sphingolipids Symptoms Testing Tumor Biology Variant Virulence Virulent Yeasts antiretroviral therapy base burden of illness capsule deletion library design differential expression experience experimental study fitness genetic resource genome wide association study improved inhibitor mortality mouse model mutant new therapeutic target novel therapeutics pathogenic fungus patient population response trait transmission process

项目摘要

Abstract Cryptococcal meningoencephalitis (CME) is one of the most important opportunistic infections affecting people with HIV/AIDS. The importance of this disease is due not only to its high incidence and mortality in this and other patient populations but also to the fact that symptoms of CME are a common sentinel event leading to the diagnosis of HIV/AIDS. Thus, many patients must first survive CME before they can benefit from the advances in HIV therapy. Unfortunately, the outcomes for CME therapy are far from acceptable, particularly in resource-limited regions with high burdens of disease. Consequently, effective and widely available therapies for CME are an unmet clinical need of global importance. Cryptococcus spp. are basidiomycetous yeasts whose primary niche is the external environment. As such, only strains and species of Cryptococcus that can transition to, and replicate within, the human host are able to cause disease. Our central premise is that an understanding of the biological mechanisms required for Cryptococcus to survive in human beings could provide new targets for therapy in the same way as studying tumor biology informs the design of new anti- cancer drugs. An important environmental distinction between the human host and the natural niche of Cryptococcus is the concentration of carbon dioxide (CO2). We hypothesized that adaptation to host levels of CO2 may represent a critical step in Cryptococcus pathogenesis. To specifically test this hypothesis, we compared the growth of C. neoformans var. grubii strains under conditions that varied only in the concentration of CO2. Consistent with our hypothesis, the growth rate was reduced at concentrations of CO2 experienced in the host. Next, we tested the CO2 tolerance of a set of environmental strains with known virulence properties in a mouse model; strains with reduced growth in the presence of host concentrations of CO2 were avirulent while those with growth rates that matched clinical isolates from human patients were virulent. We, therefore, have discovered that CO2 tolerance is a previously unrecognized host environment-associated virulence attribute of C. neoformans. Accordingly, the goal of this proposal is to identify the genetic, transcriptional, and regulatory responses that allow specific strains of C. neoformans to respond to host concentrations of CO2 and, thereby, cause CME. To accomplish these goals, we propose the following specific aims: Aim 1. Characterize the virulence, transcriptional, and genomic distinctions between CO2- tolerant and -non-tolerant C. neoformans strains; Aim 2. Identify genes required for CO2 tolerance through targeted and large-scale genetic screening; and Aim 3. Determine the molecular mechanisms of genes required for C. neoformans CO2 response. Successful execution of these aims will not only further our understanding C. neoformans pathogenesis and host survival but also identify new molecular targets for future exploration as drug targets.

抽象的隐球菌性脑膜脑炎（CME）是影响人类的最重要的机会性感染之一患有艾滋病毒/艾滋病。这种疾病的重要性不仅在于其在该地区的高发病率和死亡率其他患者群体，而且还考虑到 CME 症状是一种常见的哨兵事件，导致艾滋病毒/艾滋病的诊断。因此，许多患者必须先熬过 CME，然后才能从 CME 中受益。 HIV治疗的进展。不幸的是，CME 治疗的结果远不能接受，特别是在资源有限、疾病负担高的地区。因此，有效且广泛可用的疗法对于 CME 来说，这是一个具有全球重要性的未满足的临床需求。隐球菌属是担子菌酵母其主要利基是外部环境。因此，只有隐球菌菌株和物种可以转移到人类宿主并在人类宿主内复制能够引起疾病。我们的中心前提是了解隐球菌在人类中生存所需的生物学机制可以提供新的治疗靶点，就像研究肿瘤生物学为设计新的抗肿瘤药物提供信息一样癌症药物。人类宿主和自然生态位之间的重要环境区别隐球菌是二氧化碳（CO2）的浓度。我们假设对宿主水平的适应 CO2 可能代表隐球菌发病机制中的关键步骤。为了具体检验这个假设，我们比较了 C. neoformans var. 的生长情况。 grubii 菌株在仅浓度变化的条件下二氧化碳。与我们的假设一致，在 CO2 浓度下生长速率降低主人。接下来，我们测试了一组具有已知毒力特性的环境菌株的 CO2 耐受性在小鼠模型中；在宿主浓度 CO2 存在下生长减少的菌株是无毒的而那些生长速度与人类患者临床分离株相匹配的病毒则具有毒性。因此，我们发现CO2耐受性与之前未被识别的宿主环境相关新型隐球菌的毒力属性。因此，该提案的目标是确定遗传、允许新型隐球菌特定菌株对宿主做出反应的转录和调节反应 CO2 浓度，从而引起 CME。为了实现这些目标，我们提出以下建议具体目标：目标 1. 表征 CO2- 之间的毒力、转录和基因组差异耐受和非耐受新型隐球菌菌株；目标 2. 通过以下方式识别 CO2 耐受性所需的基因有针对性的大规模基因筛查；目标 3. 确定基因的分子机制新型隐球菌 CO2 反应所需。这些目标的成功执行不仅将进一步推动我们了解新型隐球菌发病机制和宿主生存，同时也确定未来的新分子靶点探索作为药物靶点。