White Matter Protection in Cerebral Ischemia

脑缺血中的白质保护

• 批准号: 9105419
• 负责人: GUODONG CAO
• 金额: $ 33.69万
• 依托单位: UNIVERSITY OF PITTSBURGH AT PITTSBURGH
• 依托单位国家: 美国
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-07-01 至 2018-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9105419
• 关键词: Accounting; Affect; Animals; Area; Blood; Blood - brain barrier anatomy; Brain; Brain Diseases; Cause of Death; Cell Death; Cells; Cerebral Ischemia; Cerebral cortex; Cerebrum; Cessation of life; Clinic; Clinical; Clinical Treatment; Communication; Cytosol; Demyelinations; Doctor of Philosophy; Endothelin-1; Enzymes; Extracellular Space; Glucose; Goals; Health; Human; Infarction; Injury; Internal Capsule; Intervention; Ischemia; Ischemic Brain Injury; Ischemic Stroke; Lead; Lesion; Light; Mediating; Microglia; Microinjections; Middle Cerebral Artery Occlusion; Molecular; Mus; Myelin; Natural regeneration; Neurological outcome; Neurons; Nicotinamide Mononucleotide; Nicotinamide adenine dinucleotide; Oligodendroglia; Oxygen; Phagocytosis; Pilot Projects; Play; Principal Investigator; Production; Proteins; Quality of life; Recombinant Proteins; Recombinants; Research; Role; Signal Pathway; Signal Transduction; Source; Stem cells; Stroke; Synapses; System; Testing; Therapeutic; Toxic effect; Transgenic Mice; Transgenic Organisms; brain dysfunction; clinically relevant; deprivation; disability; enzyme biosynthesis; extracellular; functional disability; functional outcomes; gray matter; improved; in vivo; ineffective therapies; insight; macrophage; neglect; neuroprotection; neurotransmission; nicotinamide phosphoribosyltransferase; novel; overexpression; post stroke; programs; promoter; protective effect; therapeutic target; treatment trial; vector; white matter; white matter injury

DESCRIPTION (provided by applicant): Cerebral white matter is highly vulnerable to cerebral ischemia13 and white matter injury (WMI) is a major cause of functional disability in stroke, the nation's third leading cause of death and the leading cause of permanent disability. Thus, interventions targeted at WMI, an area that remains relatively understudied and poorly understood, may significantly improve post-stroke quality of life. Nicotinamide phosphoribosyltransferase (NAMPT) primarily localizes in the cytosol and functions as the rate-limiting enzyme for the biosynthesis of nicotinamide adenine dinucleotide (NAD)14. NAMPT is neuroprotective against cerebral ischemia15,16. In non-CNS systems, NAMPT can be found in the extracellular space (eNAMPT) and circulates systemically in the blood. Whether the CNS also has eNAMPT and the role of this eNAMPT remains unknown. In our pilot studies, we first detected that neural cells secrete NAMPT into the extracellular space and that eNAMPT, but not its intracellular counterpart (iNAMPT), is selectively induced after ischemia, implying that extracellular NAMPT may play a role in ischemia. Increased NAMPT levels are present in the extracellular space and in white matter after ischemia in neuron-specific transgenic mice. Most importantly, in addition to gray matter protection, we found that NAMPT transgenic overexpression protects against WMI after ischemia. These findings lead us to speculate that extracellular NAMPT may mediate white matter protection after ischemia. In line with this, we found that recombinant NAMPT protein protects oligodendrocytes against ischemia-like injury induced by oxygen glucose deprivation (OGD) and AMPA toxicity. More importantly, we found that exogenously administered NAMPT protein can cross the blood brain barrier and protect against ischemic WMI in vivo. Further studies found that recombinant NAMPT protein protects against cell death of oligodendrocytes and its progenitor cells (OPCs) induced by ischemia, and enhances the differentiation of OPCs into mature oligodendrocytes. These findings suggest that NAMPT may directly protect against WMI via inhibiting oligodendrocyte death and enhancing the maturation of OPCs. We found that NAMPT also enhances microglial myelin phagocytosis. This is important because damaged myelin is believed to suppress the maturation of OPCs and cause demyelination in many pathological conditions. Thus NAMPT may indirectly enhance oligodendrogenesis via modulating microglial myelin phagocytosis. The objective of this project is to further test the white matter protective effect of NAMPT and its underlying mechanisms, and to develop a novel and clinically relevant therapeutic approach for white matter protection after cerebral ischemia. The central hypothesis to be tested is that NAMPT protects against WMI via enhancing oligodendrocytic protection/ regeneration and microglia-mediated myelin phagocytosis. Focal ischemia will be induced in mice by middle cerebral artery occlusion (MCAO) The following Specific Aims are proposed: Aim 1: Test the hypothesis that systemic administration of NAMPT protein protects against WMI induced by focal ischemia. The proposed study will test the potential translational value of NAMPT in treating WMI induced by focal cerebral ischemia. NAMPT recombinant protein will be administrated intraperitoneally to mice and the effect of NAMPT on ischemic brain injury will be quantitatively evaluated. The endpoints for assessment include infarct volume, WMI, and neurological outcomes. Aim 2: Test the hypothesis that NAMPT protects against WMI by inhibiting oligodendrocytic death and enhancing oligodendrogenesis after cerebral ischemia. The proposed study will test whether systemic administration of NAMPT protein reduces oligodendrocyte death after focal ischemia. We will also test whether NAMPT stimulates the regeneration of oligodendrocytes after ischemia. Aim 3: Test the hypothesis that NAMPT protects against WMI by enhancing microglial myelin phagocytosis. Two approaches will be used to elevate NAMPT levels: systemic administration of NAMPT protein and microglia-targeted NAMPT overexpression via an AAV9 vector driven by microglia/macrophage specific F4/80 promoter. The effect of NAMPT on microglial myelin phagocytosis, oligodendrogenesis, WMI, and functional outcomes after ischemia will be evaluated. PHS 398/2590 (Rev. 06/09) Page Continuation Format Page

描述（由申请人提供）：脑白色物质极易受到脑缺血13的影响，白色物质损伤（白质损伤）是中风功能性残疾的主要原因，是美国第三大死亡原因和永久性残疾的主要原因。因此，针对脑卒中这一研究相对不足和了解不多的领域的干预措施可能会显著改善卒中后生活质量。 烟酰胺磷酸核糖基转移酶（NAMPT）主要定位于细胞溶质中，并作为烟酰胺腺嘌呤二核苷酸（NAD）14生物合成的限速酶发挥作用。NAMPT对脑缺血具有神经保护作用15，16。在非CNS系统中，NAMPT可以在细胞外间隙（eNAMPT）中发现，并在血液中全身循环。CNS是否也有eNAMPT以及这种eNAMPT的作用仍然未知。在我们的初步研究中，我们首先检测到神经细胞分泌NAMPT进入细胞外空间，并且在缺血后选择性地诱导eNAMPT，而不是其细胞内对应物（iNAMPT），这意味着细胞外NAMPT可能在缺血中起作用。神经元特异性转基因小鼠缺血后细胞外间隙和白色物质中NAMPT水平升高。最重要的是，除了灰质保护外，我们发现NAMPT转基因过表达可保护缺血后的脑缺血。这些发现使我们推测细胞外NAMPT可能介导缺血后的白色物质保护。与此一致，我们发现重组NAMPT蛋白保护少突胶质细胞免受氧葡萄糖剥夺（OGD）和AMPA毒性诱导的缺血样损伤。更重要的是，我们发现外源性给予NAMPT蛋白可以穿过血脑屏障并在体内防止缺血性WMI。进一步的研究发现，重组NAMPT蛋白能保护缺血诱导的少突胶质细胞及其祖细胞（OPCs）的细胞死亡，并促进OPCs向成熟少突胶质细胞的分化。这些结果表明，NAMPT可能通过抑制少突胶质细胞的死亡和促进OPCs的成熟来直接保护细胞免受损伤。我们发现，NAMPT也增强小胶质细胞髓鞘吞噬作用。这是重要的，因为据信受损的髓鞘抑制OPC的成熟并在许多病理状况下引起脱髓鞘。因此，NAMPT可能通过调节小胶质细胞髓鞘吞噬作用间接增强少突胶质细胞的发生。本项目的目的是进一步测试NAMPT的白色保护作用及其潜在机制，并开发一种新的和临床相关的脑缺血后白色保护治疗方法。待检验的中心假设是NAMPT通过增强少突胶质细胞保护/再生和小胶质细胞介导的髓鞘吞噬作用来保护免受髓鞘损伤。通过大脑中动脉闭塞（MCAO）将在小鼠中诱导局灶性缺血。提出以下具体目的：目的1：检验NAMPT蛋白的全身施用对抗局灶性缺血诱导的脑缺血的假设。该研究将测试NAMPT在治疗由局灶性脑缺血引起的脑缺血中的潜在转化价值。将NAMPT重组蛋白腹腔内给予小鼠，定量评价NAMPT对缺血性脑损伤的作用。评估的终点包括梗死体积、梗死面积和神经学结局。目标二：验证NAMPT通过抑制脑缺血后少突胶质细胞死亡和增强少突胶质细胞生成来保护脑缺血的假设。该研究将测试全身给予NAMPT蛋白是否减少局灶性缺血后少突胶质细胞死亡。我们还将测试NAMPT是否刺激缺血后少突胶质细胞的再生。目的3：检验NAMPT通过增强小胶质细胞髓鞘吞噬作用来保护免受神经胶质细胞损伤的假设。将使用两种方法来提高NAMPT水平：全身施用NAMPT蛋白和经由由小胶质细胞/巨噬细胞特异性F4/80启动子驱动的AAV 9载体的小胶质细胞靶向NAMPT过表达。将评价NAMPT对小胶质细胞髓鞘吞噬作用、少突胶质细胞生成、神经再生和缺血后功能结局的影响。PHS 398/2590（Rev.06/09）