Sodium Channels and Neuroprotection in Neuroinflammatory Disorders

神经炎症性疾病中的钠通道和神经保护

• 批准号: 8085198
• 负责人: Stephen Waxman
• 金额: --
• 依托单位: VA CONNECTICUT HEALTHCARE SYSTEM
• 依托单位国家: 美国
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-10-01 至 2014-09-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8085198
• 关键词: Acute; Anti-Inflammatory Agents; Anti-inflammatory; Astrocytes; Astrocytosis; Attenuated; Axon; Axotomy; Back; Carbamazepine; Cells; Cicatrix; Clinical; Clinical Research; Clinical Trials; Data; Demyelinations; Disease; Exhibits; Experimental Autoimmune Encephalomyelitis; Health; Human; Immune; In Vitro; Inflammation; Inflammatory; Inflammatory Response; Ion Channel; Knock-out; Laboratories; Lead; Lesion; Leukocytes; MAPK14 gene; MAPK8 gene; Mediating; Methods; Microglia; Mitogen-Activated Protein Kinases; Modeling; Molecular; Multiple Sclerosis; Multiple Sclerosis Lesions; Mus; Nerve Degeneration; Neuroprotective Agents; Pathway interactions; Phagocytosis; Phenytoin; Phosphoric Monoester Hydrolases; Play; Progress Reports; Property; Regulation; Role; Signal Pathway; Site; Sodium Channel; Sodium Channel Blockers; Spinal cord injury; Staging; Testing; Tissues; Up-Regulation; Veterans; Withdrawal; Work; axonal degeneration; channel blockers; cytokine; disability; in vivo; injured; interest; knock-down; macrophage; migration; mortality; neuroinflammation; neuroprotection; response; restoration; small hairpin RNA; transmission process; voltage

DESCRIPTION (provided by applicant): My laboratory is interested in neuroprotective approaches in neuroinflammatory disorders, including MS and SCI, where inflammation has been shown to occur within the injured spinal cord. In addition to studies that target axonal ion channels for axonal neuroprotection in disorders such as MS, we are interested in the contribution of voltage-gated Na channels within glial and immune cells to their functions in neuroinflammatory diseases, and in the effects of Na channel block in these cells. In this proposal, we focus on the following Specific Aims: I. Sodium Channel Blockers and Neuroprotection in Neuroinflammatory Disorders We have demonstrated that Na channel blockers have anti-inflammatory and neuroprotective effects in mice with EAE, but we observed acute worsening following Na channel blocker withdrawal. Several clinical studies of Na channel blockers in MS are ongoing. We will now determine whether exacerbation of EAE is unique to C57/BL6 mice and whether withdrawal of other Na channel blockers exacerbates EAE. II. Sodium Channel Nav1.5 and Functions of Astrocytes in Neuroinflammation We have demonstrated that human astrocytes express Na channels and that reactive astrocytes exhibit robust upregulation of Nav1.5 at the borders of, and within, MS lesions. We will now determine the contribution of Na channels to effector roles of astrocytes in neuroinflammatory disorders, using methods that include shRNA knock-down and Cre/lox knockouts. III. Sodium Channels and Functions of Microglia We have shown that Nav1.5 and Nav1.6 are present and functional within microglia / macrophages, and that Na channel blockade attenuates their migration and phagocytosis. However, the effects of Na channel blockade on other microglial/macrophage functions is less well understood, and there is a need to understand signaling pathways that control microglial/macrophage function. We have shown that ERK, p38 and JNK regulate migration of microglia, and that levels of phosphorylated ERK are attenuated in microglia following Na channel blockade. Recently, it was shown that induction of mitogen-activated protein kinase phosphatase (MPK), which dephosphorylates ERK, reduces migration of microglia. We will now examine the contribution of Na channels to multiple functions and signaling pathways of activated microglia. Injured axons in the CNS can undergo substantial retraction (die-back) from the initial site of axotomy. This can interfere with functional transmission along more proximal, initially uninjured axonal branches; or may lead to degeneration of sustaining collaterals and neuronal degeneration. We and others have demonstrated that microglia/macrophages can engulf transected axonal ovoids, but details of the role of microglia in axonal degeneration are not yet understood. We will therefore study the role of microglia/macrophages in axonal degeneration. IV. Studies in Human MS Tissue Building upon our prior studies on human MS tissue, we will extrapolate from our in vitro studies and studies with EAE to test the hypotheses in human MS lesions that astrocytes at the active edge of MS lesions show different properties in terms of Na channel expression compared to astrocytes in central parts of these lesions; that microglia/macrophages at the active border of MS lesions show different properties in terms of Na channel expression compared to microglia/macrophages in central parts of these lesions; and that microglia/ macrophages mediate axonal die-back in MS. PUBLIC HEALTH RELEVANCE: Multiple sclerosis (MS) and spinal cord injury (SCI) are major health challenges for the VA. There are currently 40,000 veterans with SCI and at least 23,000 veterans with MS. The inflammatory response in SCI and MS contributes significantly to demyelination and axonal degeneration, resulting in substantial disability. Na channels play pivotal roles in MS and SCI, both in the restoration of conduction following demyelination, and in a degenerative cascade that leads to axonal loss. Our recent work demonstrates that Na channels contribute to regulation of function in microglia/macrophages in neuroinflammatory disorders. Clinical studies of several Na channel blockers as potential neuroprotective agents in MS have been planned and/or launched. However, we have demonstrated that withdrawal of phenytoin and carbamazepine from mice with EAE results in acute exacerbation and inflammatory rebound associated with significant mortality. Thus, it is critically important to more fully understand the roles of Na channels, and of Na channel block, in neuro-inflammatory disorders.

描述（由申请人提供）： 我的实验室对神经炎性疾病的神经保护方法感兴趣，包括MS和SCI，其中炎症已被证明发生在受伤的脊髓内。除了针对轴突离子通道在MS等疾病中用于轴突神经保护的研究外，我们还对神经胶质细胞和免疫细胞内电压门控Na通道在神经炎症性疾病中的作用以及Na通道阻滞在这些细胞中的作用感兴趣。在本提案中，我们着重于以下具体目标：钠通道阻滞剂和神经炎性疾病中的神经保护我们已经证明Na通道阻滞剂在患有EAE的小鼠中具有抗炎和神经保护作用，但是我们观察到Na通道阻滞剂停药后急性恶化。MS中Na通道阻滞剂的几项临床研究正在进行中。我们现在将确定EAE的恶化是否是C57/BL 6小鼠所独有的，以及其他Na通道阻滞剂的停用是否会加重EAE。二.钠通道Nav1.5和星形胶质细胞在神经炎症中的功能我们已经证明，人类星形胶质细胞表达Na通道，并且反应性星形胶质细胞在MS病变的边缘和内部表现出强烈的Nav1.5上调。我们现在将使用包括shRNA敲除和Cre/lox敲除的方法来确定Na通道对星形胶质细胞在神经炎性疾病中的效应器作用的贡献。三.钠通道和小胶质细胞的功能我们已经表明，Nav1.5和Nav1.6是存在的和功能的小胶质细胞/巨噬细胞，钠通道阻断减弱他们的迁移和吞噬。然而，Na通道阻断对其他小胶质细胞/巨噬细胞功能的影响还不太清楚，需要了解控制小胶质细胞/巨噬细胞功能的信号通路。我们已经表明，ERK，p38和JNK调节小胶质细胞的迁移，磷酸化ERK的水平在Na通道阻断后的小胶质细胞中减弱。最近，有研究表明，诱导丝裂原活化蛋白激酶磷酸酶（MPK），使ERK去磷酸化，减少小胶质细胞的迁移。我们现在将研究Na通道对激活的小胶质细胞的多种功能和信号通路的贡献。CNS中受损的轴突可以从轴突切断的初始部位经历实质性回缩（死回）。这可能会干扰沿着更近端的、最初未受伤的轴突分支的功能传递;或者可能导致维持侧支的变性和神经元变性。我们和其他人已经证明，小胶质细胞/巨噬细胞可以吞噬横断的轴突卵形体，但小胶质细胞在轴突变性中的作用的细节还不清楚。因此，我们将研究小胶质细胞/巨噬细胞在轴突变性中的作用。四.在我们先前对人MS组织的研究的基础上，我们将从我们的体外研究和EAE研究中推断，以测试人MS病变中的假设，即与这些病变中心部分的星形胶质细胞相比，MS病变活动边缘的星形胶质细胞在Na通道表达方面显示出不同的性质; MS病变活动边界处的小胶质细胞/巨噬细胞与这些病变中心部分的小胶质细胞/巨噬细胞相比在Na通道表达方面显示出不同的性质;并且小胶质细胞/巨噬细胞介导MS中的轴突死亡。 公共卫生相关性： 多发性硬化症（MS）和脊髓损伤（SCI）是VA的主要健康挑战。目前有40，000名退伍军人患有SCI，至少有23，000名退伍军人患有MS。SCI和MS中的炎症反应显著促进脱髓鞘和轴突变性，导致严重残疾。Na通道在MS和SCI中起关键作用，既在脱髓鞘后恢复传导，又在导致轴突损失的退行性级联反应中。我们最近的工作表明，Na通道有助于调节神经炎症性疾病中小胶质细胞/巨噬细胞的功能。已经计划和/或启动了几种Na通道阻滞剂作为MS潜在神经保护剂的临床研究。然而，我们已经证明，从EAE小鼠中停用苯妥英钠和卡马西平会导致急性加重和炎症反弹，并伴有显著的死亡率。因此，更全面地了解Na通道和Na通道阻滞在神经炎性疾病中的作用至关重要。