Pathogenesis of CNS infection and injury

中枢神经系统感染和损伤的发病机制

• 批准号: 8746841
• 负责人: Dorian McGavern
• 金额: $ 151.32万
• 依托单位: NATIONAL INSTITUTE OF NEUROLOGICAL DISORDERS AND STROKE
• 依托单位国家: 美国
• 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/8746841
• 关键词: Accounting; Acute; Adult; Adverse effects; Age; Age-Years; Antigen-Presenting Cells; Arboviruses; Arenavirus; B-Lymphocytes; Blood; Blood Vessels; Brain; CCL3 gene; CD4 Positive T Lymphocytes; CD8B1 gene; Cells; Central Nervous System Diseases; Central Nervous System Infections; Central Nervous System Parasitic Infections; Cerebrospinal Fluid; Child; Climate; Cryptococcus neoformans infection; Data; Dendritic Cells; Development; Disease; Disorder by Site; Encephalitis; Enterovirus; Epidemiologic Studies; Fever; Gene Cluster; Gene Expression; Gene Expression Profile; Genes; Genomics; Goals; HIV-1; Headache; Herpesviridae; Homeostasis; Human; Image Analysis; Immune; Immune response; Immune system; Immunity; Immunocompromised Host; Incidence; Infection; Infectious Agent; Inflammatory; Inflammatory Response; Injury; Interferon Type I; Interferons; Laser Scanning Microscopy; Left; Life; Link; Lymphocyte; Mediator of activation protein; Meningeal; Meninges; Meningitis; Microbe; Microglia; Modeling; Molecular; Mumps virus; Myelitis; Myelogenous; Myeloid Cells; Neck; Neuraxis; Neurologic; Outcome; Pathogenesis; Pathology; Pathway interactions; Pattern; Persons; Plasmodium berghei; Positioning Attribute; Process; Reaction; Recruitment Activity; Route; Seizures; Sentinel; Signal Transduction; Staging; Sterility; Symptoms; T-Lymphocyte; Therapeutic; Therapeutic Intervention; Thinking; Time; Translating; Traumatic Brain Injury; Vesicular stomatitis Indiana virus; Viral; Viral Load result; Viral meningitis; Virus; Virus Diseases; cell killing; chemokine; cytotoxic; disability; human disease; injured; insight; interest; intravital imaging; macrophage; monocyte; mortality; nervous system disorder; neurotropic virus; neutrophil; novel; pathogen; programs; relating to nervous system; response; response to injury; tissue repair; two-photon

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 (LCMV, 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 (TPM), 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 (transcranial delivery) and watch how this locally 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 demonstrated by TPM 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. Breakdown of vasculature by innate immune cells appears to be a general inflammatory reaction induced by CNS infection, as we have observed similar pathology following encephalitic virus (e.g. vesicular stomatitis virus) and parasitic (e.g. plasmodium berghei) infection. We are in the process of determining whether viral and parasitic CNS infections share common molecular mediators of vascular breakdown and also attempting to therapeutically disconnect the pathogenic link between innate and adaptive immune cells that results in vascular pathology. We also recently discovered that type I interferon (IFN-I) is an overarching master regulator of CNS immunity and may be amenable to therapeutic manipulation following infection. The CNS is inhabited by an elaborate network of specialized antigen presenting cells that include microglia, macrophages, and dendritic cells. These cells participate in CNS homeostasis, and when prompted, can initiate vigorous inflammatory responses associated with outcomes varying from tissue repair to neurological disease. Deciphering the innate pathways that trigger these cells to respond dynamically in the living brain is critical to the development of CNS immunomodulatory therapies. We sought novel mechanistic insights into how the brain responds innately to the establishment of a viral infection by conducting the first comprehensive genomic and real-time imaging analyses of a pure innate immune response mounted against a noncytopathic arenavirus (i.e., LCMV). LCMV does not kill the cells it infects, thus eliminating release of damage associated molecular pattern molecules that drive sterile injury responses. To determine how the brain responded innately to a noncytopathic virus, we analyzed patterns of gene expression at different stages of viral persistence. This revealed that the brain initially mounts a robust innate immune response (585 differentially regulated genes) that is silenced over time. Many of these were type I interferon stimulated genes (ISGs) that clustered into an interactive network indicative of coordinated anti-viral programming. To determine how this program translated into innate immune cell dynamics, we used TPM to visualize myeloid sentinels in real-time as they mounted their response to infection. Myeloid sentinels responded vigorously to infection through enhanced vascular patrolling and morphological transformations that promoted viral sequestration. Interestingly, this entire innate program (at the genomic and dynamic levels) was silenced as virus established widespread persistence in the brain. These data suggested that LCMV was able to quench the anti-viral program over time and that the brain contained a bottleneck in its innate program. This bottleneck was determined to be IFN-I signaling. To our surprise, we revealed that all myeloid cell dynamics and innate gene expression were completely silenced in the absence of IFN-I signaling, despite elevated viral loads. Importantly, we have identified an Achilles heel in the brains innate defense to a noncytopathic viral infection. The program has no redundancy and is linked exclusively to IFN-I. If IFN-I signaling is deactivated, the innate response is completely silenced, which likely explains why so many neurotropic viruses have acquired strategies to dampen the IFN-I pathway. Our results also suggest that it should also be possible to therapeutically dampen IFN-I signaling and ameliorate some of the adverse effects associated with CNS 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（LCMV，囊泡口腔炎病毒），寄生虫（Berghei疟原虫）和真菌（新生虫的加密摄氏）感染，以识别免疫系统如何应对这些不同挑战的免疫系统的相似性和差异。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，我们利用一种当代方法，称为静脉内两光子激光扫描显微镜（TPM），这使我们能够观察免疫细胞实时在活大脑中运行。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。我们还可以将治疗化合物施用到观看窗口（经颅输送）中，并观察该化合物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。 Using the LCMV model of viral meningitis, we demonstrated by TPM 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.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。 先天性免疫细胞对脉管系统的分解似乎是CNS感染引起的一般炎症反应，因为我们观察到脑性病毒（例如囊泡气孔病毒）和寄生虫（例如疟原虫berghei）感染后观察到的类似病理。 我们正在确定病毒和寄生中枢神经系统感染是否具有血管崩溃的常见分子介质，并且还试图通过治疗性断开与先天性和适应性免疫细胞之间的致病联系，从而导致血管病理。 我们最近还发现，I型干扰素（IFN-I）是CNS免疫的总体调节剂，可能会在感染后接受治疗操作。 中枢神经系统由包括小胶质细胞，巨噬细胞和树突状细胞在内的专门抗原呈现细胞的精细网络居住。 这些细胞参与中枢神经系统稳态，并在提示时可以发起与结局相关的剧烈炎症反应，从组织修复到神经系统疾病。 破译触发这些细胞在活大脑中动态反应的先天途径对CNS免疫调节疗法的发展至关重要。 我们寻求新的机械洞察力，即大脑如何通过对针对非脊椎病毒的纯天生免疫反应进行首次全面的基因组和实时成像分析来天生对病毒感染的反应（即LCMV）。 LCMV不会杀死其感染的细胞，从而消除了驱动无菌损伤反应的损伤相关分子模式分子的释放。 为了确定大脑天生对非肿瘤病毒的反应，我们在病毒持久性的不同阶段分析了基因表达的模式。 这表明大脑最初安装了稳健的先天免疫反应（585个差异调节的基因），随着时间的流逝会被沉默。 其中许多是I型干扰素刺激基因（ISG），它们聚集在指示协调的反病毒编程的交互式网络中。 为了确定该程序如何转化为先天免疫细胞动力学，我们使用TPM实时可视化髓样前哨，因为它们安装了对感染的反应。 髓样哨兵通过增强的血管巡逻和形态转化，对促进病毒隔离的形态转化产生了积极的反应。 有趣的是，随着病毒在大脑中建立了广泛的持久性，整个先天程序（在基因组和动态水平上）被沉默。 这些数据表明，LCMV能够随着时间的流逝而消除抗病毒计划，并且大脑在其先天程序中包含瓶颈。 该瓶颈被确定为IFN-I信号传导。令我们惊讶的是，我们透露，尽管病毒负荷升高，但在没有IFN-I信号传导的情况下，所有髓样细胞动力学和先天基因表达都被完全沉默。 重要的是，我们已经确定了大脑天生防御的致命弱点，以表现为非肿瘤病毒感染。 该程序没有冗余，并且仅链接到IFN-I。 如果取消IFN-I信号传导，那么先天反应将完全沉默，这很可能解释了为什么如此多的神经性病毒已经获得了抑制IFN-I途径的策略。 我们的结果还表明，还应该可以在治疗上抑制IFN-I信号传导并改善与CNS感染相关的一些不良反应。