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症性疾病（包括多发性硬化症和脊髓损伤）的神经保护方法感兴趣，这些疾病已被证明炎症发生在受损的脊髓内。除了针对多发性硬化症等疾病中轴突离子通道进行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 通道对其在神经炎症疾病中的功能的贡献以及 Na 通道阻断的影响感兴趣在这些细胞中。在本提案中，我们重点关注以下具体目标： I. 钠通道阻滞剂和神经炎症性疾病中的神经保护 我们已经证明钠通道阻滞剂对 EAE 小鼠具有抗炎和神经保护作用，但我们观察到钠通道阻滞剂后病情急性恶化撤回。 Na 通道阻滞剂治疗多发性硬化症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/BL6 小鼠所特有的，以及其他 Na 通道阻滞剂的停用是否会加剧 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 病变的边界和内部表现出 Nav1.5 的强劲上调。我们现在将使用 shRNA 敲低和 Cre/lox 敲除等方法确定 Na 通道对神经炎症性疾病中星形胶质细胞效应器作用的贡献。三．小胶质细胞的钠通道和功能 我们已经证明，Nav1.5 和 Nav1.6 在小胶质细胞/巨噬细胞内存在并发挥功能，并且钠通道阻断会减弱它们的迁移和吞噬作用。然而，Na通道阻断对其他小胶质细胞/巨噬细胞功能的影响尚不清楚，因此需要了解控制小胶质细胞/巨噬细胞功能的信号通路。我们已经证明 ERK、p38 和 JNK 调节小胶质细胞的迁移，并且在 Na 通道阻断后，小胶质细胞中磷酸化 ERK 的水平减弱。最近，研究表明，诱导丝裂原激活蛋白激酶磷酸酶 (MPK) 使 ERK 去磷酸化，可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。中枢神经系统中受损的轴突可能会从轴索切断术的初始部位大幅回缩（枯死）。这会干扰沿着更近端、最初未受伤的轴突分支的功能传递；或可能导致络脉退化和神经元退化。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圆形，但小胶质细胞在轴突变性中的作用细节尚不清楚。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．人类多发性硬化症组织的研究 基于我们之前对人类多发性硬化症组织的研究，我们将从我们的体外研究和 EAE 研究中进行推断，以测试人类多发性硬化症病变的假设，即多发性硬化症病变活动边缘的星形胶质细胞在以下方面表现出不同的特性：与这些病变中心部分的星形胶质细胞相比，Na 通道表达；与这些病变中心部分的小胶质细胞/巨噬细胞相比，多发性硬化症病变活动边缘的小胶质细胞/巨噬细胞在Na通道表达方面表现出不同的特性；小胶质细胞/巨噬细胞介导多发性硬化症中的轴突死亡。 公共卫生相关性： 多发性硬化症 (MS) 和脊髓损伤 (SCI) 是退伍军人管理局面临的主要健康挑战。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 中的炎症反应显着导致脱髓鞘和轴突变性，从而导致严重残疾。 Na 通道在 MS 和 SCI 中发挥着关键作用，无论是在脱髓鞘后的传导恢复中，还是在导致轴突丢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。几种 Na 通道阻滞剂作为多发性硬化症潜在神经保护剂的临床研究已经计划和/或启动。然而，我们已经证明，从患有 EAE 的小鼠体内停用苯妥英和卡马西平会导致急性加重和炎症反弹，并导致显着的死亡率。因此，更全面地了解 Na 通道和 Na 通道阻滞在神经炎症性疾病中的作用至关重要。