Interferon regulation of the blood brain barrier during West Nile encephalitis

摘要/摘要 这项建议的目的是阐明I型干扰素(干扰素)在血脑中的调节作用。 西尼罗河病毒脑炎期间的屏障(BBB)。西尼罗河病毒是一种由蚊子传播的黄病毒，现在流行于 北美。在过去的十年里，西尼罗河病毒导致了致命的病毒性脑炎在中国的流行。 美国。西尼罗河病机，尤其是病原体如何侵入中枢神经系统 (CNS)，人们对此仍知之甚少。在正常情况下，中枢神经系统受到保护，不受 血脑屏障的循环，由脑微血管内皮细胞(BMEC)紧密连接的界面 连接，并由相邻的星形细胞端足支撑[1]。然而，西尼罗河病毒能够通过 机制未知，并在神经元和其他实质中枢神经组织中建立感染[2，3]。氯化萘 感染导致免疫激活，从而失调血脑屏障，便于获得必要的抗病毒药物 在感染期间将白细胞输送到中枢神经系统；然而，将感染的白细胞输送到中枢神经系统也可能提供 西尼罗河病毒侵袭神经的机会[4，5]。此外，尽管跨血脑屏障免疫贩运对于 CNS病毒清除、CNS对损伤的脆弱性及其有限的修复能力可导致 抗病毒免疫反应中的显著旁观者损伤和免疫病理学。因此，血脑屏障必须是 在中枢神经系统感染期间受到严格控制，并在促进抗病毒白细胞进入部位之间取得平衡 保护中枢神经系统免受免疫介导的损害和潜在的病原体暴露 循环病毒和受感染的宿主免疫细胞。 抗病毒细胞因子信号可能是实现这种平衡的一种机制。作为一名少校 西尼罗河病毒的系统免疫反应的组成部分，I型干扰素家族的天然免疫细胞因子 在通过直接抗病毒保护CNS和外周组织免受感染方面至关重要 适应性免疫反应的活动和促进[6-8]。有趣的是，I型干扰素已经另外 在中枢神经系统自身免疫的背景下，显示在血脑屏障发挥抗炎特性，增强 内皮屏障的完整性和阻碍白细胞结合内皮细胞和迁移到 CNS[9，10]。然而，在病毒性脑炎期间，I型干扰素在血脑屏障的作用尚未得到证实。 调查过了。我们实验室使用体外血脑屏障模型进行的初步研究表明， 西尼罗河病毒感染后BMEC和星形胶质细胞中I型干扰素信号的诱导增强 内皮屏障功能和减少跨内皮细胞病毒和免疫运输。在这些基础上构建 体外发现，我们建议使用已建立的WNV脑炎小鼠模型，该模型具有细胞特异性 为了更好地了解内皮细胞或星形胶质细胞中I型干扰素受体(IFNAR)的缺失 血脑屏障上的I型干扰素信号影响神经侵袭和中枢神经系统病毒的发病机制。此外，我们还将 检测I型干扰素对中枢抗病毒免疫转运及随后病毒的潜在调节作用 清除和/或免疫病理学。我们假设I型干扰素是血脑屏障的关键调节因子。 西尼罗河病毒感染，保护屏障完整性，限制西尼罗河病毒进入中枢神经系统，并限制中枢神经系统 西尼罗河病毒脑炎时的免疫渗透和损伤。

Summary/Abstract The goal of this proposal is to elucidate a regulatory role for type-I interferon (IFN) at the blood brain barrier (BBB) during West Nile virus (WNV) encephalitis. WNV is a mosquito-borne flavivirus, now endemic in North America. Over the past decade, WNV has caused a growing epidemic of lethal viral encephalitis in the United States. West Nile pathogenesis, particularly how the pathogen infiltrates the central nervous system (CNS), remains poorly understood. Under normal conditions, the CNS is protected from pathogens in the circulation by the BBB, an interface consisting of brain microvascular endothelial cells (BMEC's) joined by tight junctions and supported by adjacent astrocyte endfeet [1]. However, WNV is able to cross the BBB through unknown mechanisms, and establishes infection in neurons and other parenchymal CNS tissues [2, 3]. CNS infection results in immune activation which dysregulates the BBB, facilitating the access of essential antiviral leukocytes to the CNS during infection; however, trafficking of infected leukocytes to the CNS may also provide an opportunity for neuroinvasion by WNV [4, 5]. Moreover, while trans-BBB immune trafficking is necessary for CNS viral clearance, the vulnerability of the CNS to damage and its limited capacity for repair can result in significant bystander injury and immunopathology during antiviral immune responses. Thus, the BBB must be tightly regulated during CNS infection, with a balance between facilitating access of antiviral leukocytes to sites of infection and protecting the CNS from immune-mediated damage and potential pathogen exposure from circulating virus and infected host immune cells. Antiviral cytokine signaling is a likely mechanism by which this balance is achieved. As a major component of the systemic immune response to WNV, the innate immune cytokines of the type-I IFN family are of critical importance in protecting both CNS and peripheral tissues from infection, via both direct antiviral activity and promotion of adaptive immune responses [6-8]. Interestingly, type-I IFN's have additionally been shown to exert anti-inflammatory properties at the BBB in the context of CNS autoimmunity, strengthening endothelial barrier integrity and impeding the ability of leukoyctes to bind endothelium and migrate into the CNS [9, 10]. However, the actions of type-I IFN at the BBB during viral encephalitis have not yet been investigated. Preliminary studies in our laboratory using in vitro models of the BBB have shown that the induction of type-I IFN signaling in both BMEC's and astrocytes after WNV infection results in enhanced endothelial barrier function and decreased transendothelial viral and immune trafficking. Building on these in vitro findings, we propose to use an established murine model of WNV encephalitis in mice with cell-specific deletions of the type-I IFN receptor (IFNAR) in endothelial cells or astrocytes in order to better understand how type-I IFN signaling at the BBB impacts neuroinvasion and CNS viral pathogenesis. In addition, we will examine potential regulatory effects of type-I IFN on CNS antiviral immune trafficking and consequent viral clearance and/or immunopathology. We hypothesize that type-I IFN is a key regulator of the BBB during WNV infection, preserving barrier integrity, restricting access of WNV to the CNS, and limiting CNS immune infiltration and damage during WNV encephalitis.