Unraveling Cryptococcus neoformans mechanisms of brain invasion and colonization

揭示新型隐球菌脑侵袭和定植机制

• 批准号: 10409726
• 负责人: Luis R Martinez
• 金额: $ 45.19万
• 依托单位: UNIVERSITY OF FLORIDA
• 依托单位国家: 美国
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-06-01 至 2024-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10409726
• 关键词: Acquired Immunodeficiency Syndrome; Actins; Address; Adhesions; Antifungal Agents; Area; Blood - brain barrier anatomy; Blood Circulation; Brain; Cell membrane; Cell physiology; Cells; Central Nervous System Infections; Cerebral Cryptococcosis; Cerebrospinal Fluid; Complex; Cryptococcal Meningitis; Cryptococcosis; Cryptococcus; Cryptococcus neoformans; Cytoskeleton; Data; Detection; Development; Diagnosis; Disease; Encapsulated; Endothelial Cells; Endothelium; Equus caballus; F2R gene; Fungal Meningitis; Goals; Growth; HIV-1; Human; Immune; Incidence; Infection; Inhalation; Intercellular Junctions; Interleukin-6; Invaded; Laboratories; Lymphatic System; MAP Kinase Gene; Meningoencephalitis; Microbe; Microglia; Molecular; Morbidity - disease rate; Neuraxis; Neurotropism; Pathogenesis; Pathologic; Patients; Penetration; Permeability; Phagocytes; Pharmacology; Phosphorylation; Polysaccharides; Predisposition; Preventive measure; Process; Production; Proteins; Purinoceptor; Role; Serum; Signal Transduction; Site; Structure of parenchyma of lung; TLR2 gene; Therapeutic; Tight Junctions; Yeasts; base; beta-arrestin; blood-brain barrier disruption; brain cell; brain endothelial cell; brain tissue; cadherin 5; capsule; cell motility; cerebral capillary; combat; cytokine; fungus; glucuronoxylomannan; in vivo; insight; junctional adhesion molecule; migration; mimetics; mortality; mouse model; novel; novel therapeutics; p38 Mitogen Activated Protein Kinase; palmidrol; polymerization; prevent; therapeutic target

Abstract The encapsulated fungus Cryptococcus neoformans (Cn) is the most common cause of fungal meningitis, with the highest rate of cryptococcosis found in AIDS patients. Despite antifungal treatment, cryptococcal meningitis is known for its high morbidity and mortality rates due to its difficult eradication from the brain. Cn’s capsule contributes directly to its pathogenesis; specifically, its main component, glucuronoxylomannan (GXM), has been associated with invasion of the brain. Studies in mouse models of cryptococcal meningoencephalitis have indicated that the portals of Cn invasion into the brain are the cerebral capillaries, which have been confirmed by pathological studies in human brain tissues. Cn can cross the blood brain barrier (BBB) as free yeast either transcellularly using the Trojan horse mechanism, and/or by paracellular passage. However, the fungal factor(s) supporting these invasive processes is/are not well-described. Therefore, the goal of this application is to dissect the cellular and signaling mechanisms by which Cn GXM dysregulates the BBB, allowing the fungus to invade the central nervous system (CNS). Furthermore, microglial (MG) cells are the main form of active immune defense in the CNS. These cells are critical for combating CNS-invading microbes, including Cn, but the specific function(s) of MG cells required to counteract GXM’s BBB damage and Cn invasion is/are poorly understood. Our central hypothesis is that GXM disrupts endothelial cells junctions and inhibits MG cell migration resulting in Cn invasion and colonization of the CNS. To address our hypothesis, we propose the following aims: (1) Determine the role of Cn GXM on BBB physical integrity in vivo; (2) Establish the cell signaling mechanisms by which Cn GXM induces human brain microvascular endothelial cell barrier permeability; and (3) Study the impact of GXM-induced inhibition of MG cell migration and control of Cn brain invasion in vivo. Identification of the mechanisms by which Cn GXM alters the BBB integrity and MG cell functions will provide novel insights into the neurotropism of this deadly infection and may offer new therapeutic opportunities and preventive measures for combating cerebral cryptococcosis, a disease that kills ~200,000 AIDS patients annually around the world.

抽象的 荚膜真菌新型隐球菌 (Cn) 是真菌性脑膜炎的最常见原因， 艾滋病患者中隐球菌病的发病率最高。尽管进行抗真菌治疗，隐球菌性脑膜炎 由于难以从大脑中根除，因此以其高发病率和死亡率而闻名。 CN的胶囊 直接促成其发病机制；具体来说，其主要成分葡萄糖醛酸木甘露聚糖（GXM）已被 与大脑的侵袭有关。隐球菌性脑膜脑炎小鼠模型的研究 表明Cn侵入大脑的门户是脑毛细血管，这一点已被证实 通过对人类脑组织的病理研究。 Cn 也可以作为游离酵母穿过血脑屏障 (BBB) 使用特洛伊木马机制跨细胞和/或通过细胞旁传代。然而，真菌因子 支持这些侵入性过程的描述尚不清楚。因此，该应用程序的目标是剖析 Cn GXM 失调 BBB 的细胞和信号传导机制，从而允许真菌侵入 中枢神经系统（CNS）。此外，小胶质细胞（MG）是主动免疫的主要形式 中枢神经系统的防御。这些细胞对于对抗中枢神经系统入侵微生物（包括 Cn）至关重要，但具体的 MG 细胞抵抗 GXM 的 BBB 损伤和 Cn 入侵所需的功能知之甚少。 我们的中心假设是 GXM 破坏内皮细胞连接并抑制 MG 细胞迁移，从而导致 CN 入侵和中枢神经系统定植。为了解决我们的假设，我们提出以下目标：（1） 确定Cn GXM对体内BBB物理完整性的作用； (2) 建立细胞信号传导机制 其中Cn GXM诱导人脑微血管内皮细胞屏障通透性； (3) 研究影响 GXM 诱导的 MG 细胞迁移抑制和体内 Cn 脑侵袭的控制。鉴定 Cn GXM 改变 BBB 完整性和 MG 细胞功能的机制将为了解 这种致命感染的神经向性，可能为以下疾病提供新的治疗机会和预防措施 对抗脑隐球菌病，这种疾病每年导致全世界约 200,000 名艾滋病患者死亡。