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: 9157553
• 负责人: Dorian McGavern
• 金额: $ 202.29万
• 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/9157553
• 关键词: Acute; Antioxidants; Astrocytes; B-Lymphocytes; Blood Vessels; Brain; Brain Injuries; CD4 Positive T Lymphocytes; CD8B1 gene; Cell Death; Cells; Central Nervous System Infections; Cerebral Malaria; Cerebrospinal Fluid; Data; Dendritic Cells; Disease; Drug Delivery Systems; Encephalitis; Environment; Extravasation; Focal Brain Injuries; Glutathione; Goals; Hour; Human; Immune; Immune response; Immune system; Infection; Infectious Agent; Inflammatory; Inflammatory Response; Injury; Kinetics; Laser Scanning Microscopy; Lesion; Life; Lymphocytic choriomeningitis virus; Meningeal; Meninges; Meningitis; Microbe; Microglia; Modeling; Molecular; Molecular Weight; Monitor; Nature; Neuraxis; Pathogenesis; Pathology; Pathway interactions; Plasmodium berghei; Process; Purinoceptor; Reaction; Reactive Oxygen Species; Receptor Signaling; Sterility; Subarachnoid Space; Symptoms; T-Lymphocyte; Therapeutic; Therapeutic Intervention; Time; Traumatic Brain Injury; Vesicular stomatitis Indiana virus; Viral; bone; brain tissue; cranium; driving force; human disease; injured; insight; interest; intravital imaging; macrophage; mild traumatic brain injury; monocyte; neurotoxicity; neutrophil; novel; novel strategies; pathogen; relating to nervous system; response; 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. 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) and parasitic (plasmodium berghei) infections to identify the similarities and differences in how the immune system responds to these unique 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. Use of fluorescent tags allows us to study the dynamics of 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. To gain novel insights into sterile immune responses in the brain, we recently developed a focal model of mild traumatic brain injury (mTBI) referred to as meningeal compression injury. Traumatic brain injuries in humans range from mild to severe and are quite diverse in nature. Our meningeal compression model reflects one type of injury among a broad spectrum. The injury is mild, focal, and occurs beneath a closed-skull. Importantly, this injury model is advantageous because it can be closely monitored by TPM and is readily amenable to local therapeutic manipulation. Using TPM we initially set out to define the pathology and innate immune reaction to focal brain injury in real-time. Following mTBI, we observed that meningeal blood vessels and macrophages were damaged within the first 30 minutes. Some vessels were occluded while others began to leak their contents into the subarachnoid space. Importantly, the vascular pathology was comparable to what was observed in humans following mTBI. We also showed that the glial limitans becomes porous following injury due to destruction of astrocytes, resulting in leakage of cerebral spinal fluid into the brain parenchyma. Destruction of the glial limitans may help explain the kinetics of cell death, which was first observed in the meninges and later spread into the parenchyma over time. The innate immune response to mTBI within the first 12 hours was characterized by a specialized microglia reaction in the brain parenchyma and the recruitment of myelomonocytic cells (monocytes and neutrophils) into the meninges. These responses were likely partitioned to maximize efficiency of the innate immune system as it attempted to deal separately with two injured, but anatomically distinct CNS environments: meninges and parenchyma. Both immune reactions were driven by purinergic receptor signaling and appeared to be neuroprotective. When the responses were inhibited, an increase in cell death was observed. To pharmacologically manipulate the mTBI reaction locally, we developed a new approached referred to as transcranial drug delivery. We discovered that the intact skull bone allows passage of low molecular weight compounds (<40,000 MW) into the underlying meninges and brain tissue. Using this approach we set out to identify and therapeutically eliminate the primary driver of mTBI lesion pathogenesis. We observed by TPM that reactive oxygen species (ROS) were generated almost immediately after injury. As a therapy, we applied the antioxidant, glutathione (GSH), transcranially (as late as 3 hours post-injury) and observed a >50% reduction in parenchyma cell death. This treatment also preserved meningeal macrophages, maintained integrity of the glial limitans, and markedly reduced the innate CNS inflammatory reaction. These exciting data demonstrate that ROS are a major driving force in mTBI pathogenesis and that there is a window of opportunity available for treatment of this condition. Delaying treatment increases the amount of irreparable brain damage and likely exposes the CNS to increasingly synergistic pathways of neurotoxicity.

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。 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（淋巴细胞绒毛膜炎病毒，囊泡性口腔炎病毒）和寄生虫（Berghei疟原虫）感染，以确定免疫系统如何应对这些独特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。荧光标签的使用使我们能够研究先天性的动力学（例如，小胶质细胞，巨噬细胞，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）免疫细胞随着疾病的发展而产生。我们还可以将治疗化合物施加到观看窗口（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。 为了获得对大脑无菌免疫反应的新见解，我们最近开发了一种轻度创伤性脑损伤（MTBI）的焦点模型，称为脑膜压缩损伤。 人类的创伤性脑损伤范围从轻度到重度，本质上是相当多样化的。 我们的脑膜压缩模型反映了广泛范围中的一种损伤。 损伤是轻度的，局灶性的，并且发生在封闭的库尔下。 重要的是，该损伤模型是有利的，因为它可以通过TPM密切监测，并且很容易受到局部治疗操作。 使用TPM，我们最初着手实时定义对局灶性脑损伤的病理和先天免疫反应。 MTBI之后，我们观察到脑膜血管和巨噬细胞在最初的30分钟内受损。 一些船只被阻塞，而另一些容器开始将其内容物泄漏到蛛网膜下腔中。 重要的是，血管病理与MTBI后人类观察到的血管病理相当。 我们还表明，由于星形胶质细胞破坏而受伤后，神经胶质极限变成多孔，导致脑脊髓液渗入脑实质中。 神经胶质极限的破坏可能有助于解释细胞死亡的动力学，该动力学首先在脑膜中观察到，然后随着时间的推移扩散到实质中。 头12小时内对MTBI的先天免疫反应的特征是在脑实质中有专门的小胶质细胞反应，并募集骨髓细胞细胞（单核细胞和嗜中性粒细胞）。 这些反应可能被分割了，以最大程度地提高先天免疫系统的效率，因为它试图分别处理两个受伤但解剖学上不同的CNS环境：脑膜和实质。 两种免疫反应均由嘌呤能受体信号传导驱动，并且似乎是神经保护作用。 当抑制反应时，观察到细胞死亡的增加。 为了在药理上操纵MTBI局部反应，我们开发了一种新方法，称为经颅药物递送。 我们发现完整的头骨骨可以将低分子量化合物（<40,000 mW）传递到潜在的脑膜和脑组织中。 使用这种方法，我们着手识别和治疗消除MTBI病变发病机理的主要驱动因素。 我们通过TPM观察到，受伤后几乎立即产生活性氧（ROS）。 作为一种疗法，我们应用了抗氧化剂，谷胱甘肽（GSH），经经颅（在伤害后3小时）进行，观察到实质细胞死亡的降低> 50％。 这种处理还保留了脑膜巨噬细胞，维持了胶质限极的完整性，并显着降低了先天中枢神经系统炎症反应。 这些令人兴奋的数据表明，ROS是MTBI发病机理中的主要驱动力，并且有机会可以治疗这种情况。 延迟治疗会增加无法弥补的脑损伤的量，并可能使CNS暴露于越来越多的神经毒性途径。