Pathogenesis of viral meningitis

病毒性脑膜炎的发病机制

基本信息

批准号：
8557083
负责人：
Dorian McGavern
金额：
$ 207.67万
依托单位：
NATIONAL INSTITUTE OF NEUROLOGICAL DISORDERS AND STROKE
依托单位国家：
美国
项目类别：
财政年份：
资助国家：
美国
起止时间：
至
项目状态：
未结题

来源：
https://reporter.nih.gov/project-details/8557083
关键词：
Accounting Acute Adult Age Age-Years Antigen-Presenting Cells Antiviral Response Arboviruses B-Lymphocytes Blood Blood Vessels Brain CCL3 gene CD4 Positive T Lymphocytes CD8B1 gene Cell Cycle Cell Cycle Stage Cell division Cells Central Nervous System Diseases Central Nervous System Infections Cerebrospinal Fluid Child Climate Cryptococcus neoformans infection Data Dendritic Cells Disease Disorder by Site Encephalitis Enterovirus Epidemiologic Studies Fever Goals HIV-1 Headache Herpesviridae Human Image Immune Immune response Immune system Immunocompromised Host Incidence Infection Infectious Agent Inflammatory Inflammatory Response Injury Institutes Laser Scanning Microscopy Left Life Lymphocyte Lymphocyte Count Lymphocytic choriomeningitis virus Lymphoid Tissue Mediator of activation protein Meningeal Meninges Meningitis Microbe Microglia Mitosis Modeling Molecular Mumps virus Myelitis Neck Neuraxis Neurologic Pathogenesis Peptide/MHC Complex Persons Plasmodium berghei Positioning Attribute Process Reaction Recruitment Activity Route Seizures Signal Transduction Site Sterility Symptoms T-Cell Proliferation T-Lymphocyte Therapeutic Therapeutic Intervention Thinking Time Tissues Traumatic Brain Injury Vesicular stomatitis Indiana virus Viral Viral meningitis Virus Virus Diseases base chemokine cytotoxic disability human disease injured insight interest macrophage monocyte mortality neutrophil novel pathogen programs relating to nervous system two-photon

项目摘要

Many inflammatory processes directly impact the function of the central nervous system (CNS) and give rise to human diseases. For example, acute infection of the CNS can induce a variety of disease states such as meningitis and encephalitis. Meningitis occurs when microbes infect the lining of the brain, whereas encephalitis is usually caused by infection of the brain itself. Epidemiological studies estimate that viral meningitis is induced with a peak monthly incidence of 1 in 100,000 persons, particularly in temperate climates. The disease is associated with symptoms that include fever, headache, stiffness of the neck, and seizures. Enteroviruses are the most common cause of viral meningitis, accounting for approximately 75-90% of the cases. Other meningitis-inducing viruses in humans include herpesviruses, human immunodeficiency virus-1, arbovirus, mumps virus, and lymphocytic choroimeningitis virus (LCMV). While complications associated with enterovirus-induced meningitis (the most common viral meningitis) in adults are rare, and are often seen in the immunocompromised, studies have shown that infection of children less than one year of age can result in mild to moderate neurological disability by the age of 5. At the other end of the spectrum, herpesviruses induce an array of CNS disorders that include encephalitis, myelitis, and meningitis, and these disorders have a very high mortality rate if left untreated. Because so many microbes have the capacity to infect and injure the CNS, it is important to uncover potential routes to pathogenesis. One of our main interests is to mechanistically define the impact of acute infections on the CNS and establish treatments to ameliorate adverse symptoms associated with these infections. We study viral (lymphocytic choriomeningitis virus, vesicular stomatitis virus), parasitic (plasmodium berghei), and fungal (cryptococcus neoformans) infections to identify the similarities and differences in how the immune system responds to these different challenges. We also study sterile inflammatory responses (i.e., traumatic brain injury) to provide insights into how CNS immune cells respond to damage in the absence of an infectious agent. To advance our understanding of neural-immune interactions during CNS inflammatory diseases, we utilize a contemporary approach referred to as intravital two-photon laser scanning microscopy (TPLSM), which allows us to watch immune cells operate in the living brain in real time. This is accomplished by using fluorescently tagged immune cells and pathogens. By using fluorescent tags, the position of the pathogen can be studied in relation to innate (e.g. microglia, monocytes, macrophages, neutrophils, dendritic cells) and adaptive (e.g. microbe-specific CD8 T cells, CD4 T cells, B cells) immune cells as a disease develops. We can also administer therapeutic compounds into the viewing window and watch how this influences the inflammatory process in real time. This powerful approach allows us to evaluate the efficacy of potential therapeutics at the site of disease. Using the LCMV model of viral meningitis, we have recently demonstrated by TPLSM that virus-specific cytotoxic lymphocytes (CTL) drive acute onset seizures during meningitis by massively recruiting myelomonocytic cells (monocytes and neutrophils), which damage meningeal blood vessels and compromise the blood-cerebral spinal fluid (CSF) barrier. Virus-specific CTL participate in myelomonocytic cell recruitment by directly producing chemokines (CCL3, 4, and 5) that attract them. These data revised our thinking about viral meningitis by demonstrating that CTL do not always cause pathogenesis by releasing of cytotoxic effector molecules; rather, they can also contribute to CNS disease by recruiting pathogenic innate immune cells. Based on our studies of other models of infection, breakdown of CNS vasculature by innate immune cells appears to be a general inflammatory reaction, and we are in the process of identifying the molecular mediators that cause this to occur. Another novel finding that emerged from our TPLSM studies pertains to division programming of T cells. Starting from a simple dynamic observation of virus-specific CTL undergoing mitosis in the LCMV infected meninges, we developed a new conceptual understanding of the T cell division programming. We elucidated a novel mechanism that gives the immune system the ability to respond more appropriately to a viral infection, and infected tissues the ability to control CTL numbers locally. The traditional view of T cell proliferation is that it is a hardwired program instituted primarily in secondary lymphoid tissues by dendritic cells. This program is quite slow, often requiring up to 24 hrs before the first round of division is observed. Even at the peak of an anti-viral response, T cell division is estimated to require 6-8 hrs, and during this time, virus continues to replicate unchecked. Interestingly, during LCMV meningitis, CTL depart lymphoid tissues and migrate through the blood while still in cell cycle. In fact, up to one third of anti-viral CTL in the blood remained in active stages of cell cycle. Using TPLSM we demonstrated that upon arrival at a site infection (meninges), CTL can engage antigen presenting cells (APCs) and undergo mitosis within just 15 minutes. We further demonstrated that the CTL division program is not hardwired, but can be influenced by APCs at the site of infection. Interactions with local APCs and cognate peptide-MHC I can advance CTL through stages of cell cycle. These data support the novel concept that the CTL division program is cumulative and results from the summation of signals accumulated systemically following viral infection. Overall, our study is the first to highlight that CTL migrate while still in cell cycle, that CTL division programming is cumulative and can be modified at the site of viral infection by interactions with APCs, and that the CNS meninges is a site permissive to CTL division. We are now in the process of devising strategies to modulate CTL division programming as a therapy to mitigate CNS diseases following infection.

许多炎症过程直接影响中枢神经系统（CNS）的功能，并引起人类疾病。例如，中枢神经系统的急性感染会诱导多种疾病状态，例如脑膜炎和脑炎。当微生物感染大脑的内膜时，脑膜炎发生，而脑炎通常是由大脑本身感染引起的。流行病学研究估计，病毒性脑膜炎是在每月100,000人中的1个峰值发病率诱导的，尤其是在温带气候中。该疾病与包括发烧，头痛，颈部僵硬和癫痫发作有关的症状有关。肠病毒是病毒性脑膜炎的最常见原因，约占病例的75-90％。人类中的其他引起脑膜炎的病毒包括疱疹病毒，人类免疫缺陷病毒-1，Arbovirus，腮腺炎病毒和淋巴细胞蛋白粘膜肾上腺炎病毒（LCMV）。 While complications associated with enterovirus-induced meningitis (the most common viral meningitis) in adults are rare, and are often seen in the immunocompromised, studies have shown that infection of children less than one year of age can result in mild to moderate neurological disability by the age of 5. At the other end of the spectrum, herpesviruses induce an array of CNS disorders that include encephalitis, myelitis, and如果未治疗，脑膜炎和这些疾病的死亡率很高。由于如此多的微生物具有感染和伤害中枢神经系统的能力，因此很重要的是发现潜在的发病机理途径。我们的主要利益之一是机械地定义急性感染对中枢神经系统的影响，并建立治疗方法以减轻与这些感染相关的不良症状。我们研究病毒（淋巴细胞欺骗性炎病毒，囊泡性气孔病毒），寄生虫（berghei疟原虫）和真菌（Neoformans）感染，以确定免疫系统如何应对这些不同的挑战的相似性和差异。我们还研究无菌炎症反应（即脑外伤），以洞悉CNS免疫细胞在没有感染剂的情况下如何响应损害。为了促进我们对中枢神经系统炎症性疾病期间神经免疫相互作用的理解，我们利用一种现代方法，称为静脉内两光子激光扫描显微镜（TPLSM），这使我们能够观察免疫细胞实时在活体大脑中运行。这是通过使用荧光标记的免疫细胞和病原体来完成的。通过使用荧光标签，可以研究病原体的位置与先天性（例如微胶质细胞，单核细胞，巨噬细胞，中性粒细胞，树突状细胞）和适应性（例如，微生物特异性CD8 T细胞，CD4 T细胞，B细胞，B细胞）免疫细胞是一种疾病而发展的。我们还可以在观看窗口中施用治疗化合物，并观察这如何实时影响炎症过程。这种强大的方法使我们能够评估疾病部位潜在治疗剂的功效。使用TPLSM，我们使用了病毒性脑膜炎的LCMV模型表明，病毒特异性细胞毒性淋巴细胞（CTL）驱动脑膜炎期间急性发作通过大量募集的脊髓细胞细胞（单亲细胞和中性粒细胞），损害脑部和组合血细胞的血细胞造成血液的血细胞和血细胞造成的（造成血液）的血细胞。病毒特异性的CTL通过直接产生吸引它们的趋化因子（CCL3、4和5）来参与脊髓细胞细胞的募集。这些数据通过证明CTL并不总是通过释放细胞毒性效应子分子来修改我们对病毒脑膜炎的思考。相反，它们也可以通过募集致病性先天免疫细胞来为中枢神经系统疾病做出贡献。基于我们对其他感染模型的研究，先天免疫细胞对CNS脉管系统的分解似乎是一种普遍的炎症反应，我们正在识别导致这种情况的分子介质。从我们的TPLSM研究中出现的另一个新颖的发现与T细胞的分裂编程有关。从对LCMV感染脑膜中有丝分裂的病毒特异性CTL进行简单的动态观察开始，我们对T细胞分裂编程有了新的概念理解。我们阐明了一种新型机制，该机制使免疫系统能够对病毒感染做出更适当的反应，并感染组织在局部控制CTL数量的能力。 T细胞增殖的传统观点是，它是一个硬连线程序，主要由树突状细胞在次级淋巴组织中产生。该程序非常慢，通常需要在观察到第一轮划分之前最多需要24小时。即使在抗病毒反应的峰值上，估计T细胞分裂需要6-8小时，在此期间，病毒继续不受检查。有趣的是，在LCMV脑膜炎期间，CTL脱离淋巴组织，并在仍处于细胞周期的同时通过血液迁移。实际上，在细胞周期的活跃阶段，血液中多达三分之一的抗病毒CTL。使用TPLSM，我们证明了到达现场感染（脑膜）后，CTL可以在短短15分钟内参与抗原呈递细胞（APC）并进行有丝分裂。我们进一步证明，CTL分区计划不是硬连线，而是在感染部位受APC的影响。与局部APC和同源肽-MHC I的相互作用可以通过细胞周期阶段提高CTL。这些数据支持了CTL分裂程序是累积性的新概念，并且是由于在病毒感染后全身累积的信号总结而产生的。总体而言，我们的研究是第一个强调CTL仍在细胞周期中迁移的研究，CTL分裂编程是累积性的，可以通过与APC的相互作用在病毒感染部位进行修改，并且CNS脑膜是CTL分裂的位点。现在，我们正在制定策略来调节CTL分区编程，以作为一种减轻感染后CNS疾病的疗法。