The role of inositol in Cryptococcus biology and pathogenesis

肌醇在隐球菌生物学和发病机制中的作用

基本信息

批准号：
10054979
负责人：
Chaoyang Xue
金额：
$ 64.97万
依托单位：
RBHS-NEW JERSEY MEDICAL SCHOOL
依托单位国家：
美国
项目类别：
财政年份：
2016
资助国家：
美国
起止时间：
2016-11-24 至 2023-10-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/10054979
关键词：
AIDS/HIV problem Animal Model Astrocytes Attenuated Binding Biological Biological Assay Biological Models Biology Blood Blood - brain barrier anatomy Brain Catabolism Cell surface Cells Central Nervous System Infections Cessation of life Chemotactic Factors Complex Cryptococcal Meningitis Cryptococcosis Cryptococcus Cryptococcus neoformans Development Disease Endothelium Environment Exhibits Extravasation Fungal Meningitis Gene Expression Regulation Genetic Transcription Goals Group Structure Growth Human Hyaluronic Acid Immune Evasion Immune response Immunity Immunocompromised Host In Vitro Infection Inositol Inositol Metabolism Pathway Knowledge Life Ligands Mediating Medical Meningitis Metabolic Pathway Metabolism Mission Modeling Modification Molecular Mus Mutagenesis Neuraxis Neurotropism Nutrient Oryctolagus cuniculus Pathogenesis Pathway interactions Patients Phospholipids Plants Play Polysaccharides Process Production RNA Role Signal Transduction Signaling Molecule Source Structure Surface System Testing Tight Junctions Time United States National Institutes of Health Virulence Virulence Factors base blood-brain barrier crossing blood-brain barrier penetration capsule cell component structure disorder control disorder prevention fungus human model human pathogen imaging approach in vitro Model in vivo in vivo Model insight monolayer mouse model mutant novel pathogen pathogenic fungus receptor transcription factor uptake whole animal imaging

项目摘要

Cryptococcus neoformans is a deadly fungal pathogen that exhibits pronounced neurotropism: it is the most common cause of fungal meningitis, particularly in immunocompromised patients, resulting in over 620,000 deaths annually. How C. neoformans cells traverse the blood-brain barrier (BBB) to infect the central nervous system (CNS) remains poorly understood. Our recent studies implicate inositol – one of the most abundant metabolites in the brain – in this process. In particular, we find that growth of C. neoformans under inositol-rich conditions enhances fungal virulence and that fungal mutants defective in inositol uptake exhibit reduced virulence, reduced capacity to transmigrate from the blood into the brain, and reduced ability to traverse a model BBB in vitro. We also find that C. neoformans compromises tight-junction integrity in vitro, promoting inositol leakage through the brain microvascular endothelial monolayer. Furthermore, we show that inositol induces the expression of fungal cell surface factors involved in virulence, including the polysaccharide capsule, a major fungal virulence factor, and hyaluronic acid (HA), a ligand important for fungal binding to the BBB. Finally, we find that growth on inositol promotes the production of capsule structures involved in immune evasion and that, conversely, C. neoformans mutants defective in inositol uptake elicit enhanced protective immunity during brain infection. Based on these results, we hypothesize that C. neoformans senses and utilizes host inositol to modify the fungal cell surface in a way that promotes penetration of the BBB and development of cryptococcal meningitis. Interestingly, C. neoformans contains an unusually complex inositol uptake system and catabolic pathway, which likely evolved from its utilization of the inositol stores of its plant reservoirs. Thus, this fungus may be uniquely adapted to thrive in the inositol-rich environment of the CNS and to utilize inositol-dependent pathways for pathogenesis. The overarching goal of this proposal is to obtain a detailed understanding of the mechanism by which C. neoformans acquires and utilizes host inositol to establish human brain infection. We propose three Specific Aims: 1) Define inositol sensing and metabolic pathways required for modifying fungal cell surface structure by using a combination of fungal mutagenesis analysis, enzymatic assays, and polysaccharide structural analysis; 2) Characterize the mechanism of inositol- mediated promotion of C. neoformans BBB crossing and CNS infection by using an in vitro BBB model system and in vivo animal models; and 3) Define the transcriptional circuits regulating inositol-dependent processes during cryptococcal brain infection by analyzing the expression and localization of fungal inositol factors and identifying transcription factors regulating their expression during infection. Together, these studies will elucidate a novel contribution of a brain metabolite, inositol, to the development of life-threatening fungal meningitis. As such, these studies promise to provide substantial insight into mechanisms by which pathogens cross the BBB and establish CNS infections.

隐孢子虫是一种致命的真菌病原体，表现出明显的神经性神经：它是最多的真菌性脑膜炎的常见原因，特别是在免疫功能低下的患者中，导致超过620,000 每年死亡。 Neofors C. Neofors细胞如何穿越血脑屏障（BBB）以感染中枢神经系统系统（中枢神经系统）仍然了解不足。我们最近的研究暗示肌醇 - 最丰富的肌醇之一在此过程中，大脑中的代谢产物。特别是，我们发现在肌醇富含肌醇下的Neoformans的生长疾病增强了真菌病毒，而真菌突变体在肌醇摄取中有缺陷降低病毒，从血液传播到大脑的能力降低，并降低遍历A的能力体外BBB模型。我们还发现，梭状芽胞杆菌在体外损害了紧密结的完整性，促进肌醇通过脑微血管内皮单层泄漏。此外，我们表明肌醇诱导病毒中涉及的真菌细胞表面因子的表达，包括多糖胶囊，一种主要的真菌病毒因子和透明质酸（HA），这是一种对真菌结合至关重要的配体 BBB。最后，我们发现肌醇增长会促进与免疫相关的胶囊结构的产生相反，逃避和相反，肌醇摄取中有缺陷的新角菌突变体引起了增强的保护性大脑感染期间的免疫力。基于这些结果，我们假设NeoFormans的感觉和利用宿主肌醇来修饰真菌细胞表面，以促进BBB的穿透和隐球菌脑膜炎的发展。有趣的是，C。Neoformans包含异常复杂的肌表示吸收系统和分解代谢途径，可能是由于其植物的肌醇存储而发展而来的水库。这是在CNS的肌醇丰富环境中壮成长的，这种真菌可以独特地适应利用肌醇依赖性途径进行发病机理。该提议的总体目标是获得详细了解C. Neoformans获得并利用宿主iNositel的机制建立人脑感染。我们提出了三个具体目标：1）定义肌醇灵敏度和代谢通过使用真菌诱变的组合修饰真菌细胞表面结构所需的途径分析，酶测定和多糖结构分析； 2）表征肌醇的机理使用体外BBB模型系统介导的Neoformans C. Neoformans BBB交叉和中枢神经系统感染和体内动物模型； 3）定义调节肌醇依赖性过程的转录电路通过分析真菌肌醇因子的表达和定位和确定转录因子在感染过程中调节其表达。这些研究将在一起阐明脑代谢物（肌醇）对威胁生命真菌的发展的新颖贡献脑膜炎。因此，这些研究有望提供对病原体的机制的实质性见解越过BBB并建立中枢神经系统感染。