White Matter Protection in Cerebral Ischemia

脑缺血中的白质保护

基本信息

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
项目类别：
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

项目摘要

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）：大脑白质极易发生脑缺血13，而白质损伤（WMI）是中风功能障碍的主要原因，中风是美国第三大死因，也是永久残疾的主要原因。因此，针对 WMI（一个研究相对较少且了解甚少的领域）的干预措施可能会显着改善中风后的生活质量。烟酰胺磷酸核糖基转移酶 (NAMPT) 主要定位于细胞质中，并作为烟酰胺腺嘌呤二核苷酸 (NAD) 生物合成的限速酶发挥作用14。 NAMPT 对脑缺血具有神经保护作用15,16。在非 CNS 系统中，NAMPT 存在于细胞外空间 (eNAMPT) 并在血液中全身循环。 CNS是否也有eNAMPT以及该eNAMPT的作用仍不清楚。在我们的初步研究中，我们首先检测到神经细胞将 NAMPT 分泌到细胞外空间，并且在缺血后选择性诱导 eNAMPT，而不是其细胞内对应物 (iNAMPT)，这意味着细胞外 NAMPT 可能在缺血中发挥作用。神经元特异性转基因小鼠缺血后，细胞外间隙和白质中的 NAMPT 水平增加。最重要的是，除了灰质保护之外，我们发现 NAMPT 转基因过表达可以预防缺血后的 WMI。这些发现使我们推测细胞外 NAMPT 可能介导缺血后的白质保护。与此相符，我们发现重组 NAMPT 蛋白可保护少突胶质细胞免受氧糖剥夺 (OGD) 和 AMPA 毒性引起的缺血样损伤。更重要的是，我们发现外源施用的NAMPT蛋白可以穿过血脑屏障并在体内预防缺血性WMI。进一步研究发现，重组NAMPT蛋白可防止缺血诱导的少突胶质细胞及其祖细胞（OPC）死亡，并增强OPC向成熟少突胶质细胞的分化。这些发现表明，NAMPT 可能通过抑制少突胶质细胞死亡和促进 OPC 成熟来直接预防 WMI。我们发现 NAMPT 还增强小胶质细胞髓磷脂的吞噬作用。这很重要，因为受损的髓磷脂被认为会抑制 OPC 的成熟，并在许多病理状况下导致脱髓鞘。因此，NAMPT 可能通过调节小胶质细胞髓磷脂吞噬作用来间接增强少突胶质细胞发生。该项目的目的是进一步测试NAMPT的白质保护作用及其潜在机制，并开发一种新颖的、具有临床意义的脑缺血后白质保护治疗方法。待测试的中心假设是 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磷脂吞噬作用来预防 WMI。通过大脑中动脉闭塞(MCAO)将在小鼠中诱发局灶性缺血。提出了以下具体目标：目标1：测试全身施用NAMPT蛋白可防止局灶性缺血诱发的WMI的假设。拟议的研究将测试 NAMPT 在治疗局灶性脑缺血引起的 WMI 中的潜在转化价值。将NAMPT重组蛋白腹腔注射给小鼠，定量评估NAMPT对缺血性脑损伤的作用。评估终点包括梗塞体积、WMI 和神经系统结果。目标 2：检验 NAMPT 通过抑制少突胶质细胞死亡和增强脑缺血后少突胶质细胞生成来预防 WMI 的假设。拟议的研究将测试全身施用 NAMPT 蛋白是否可以减少局灶性缺血后少突胶质细胞的死亡。我们还将测试 NAMPT 是否刺激缺血后少突胶质细胞的再生。目标 3：检验 NAMPT 通过增强小胶质细胞髓磷脂吞噬作用来预防 WMI 的假设。将使用两种方法来提高 NAMPT 水平：系统施用 NAMPT 蛋白和通过由小胶质细胞/巨噬细胞特异性 F4/80 启动子驱动的 AAV9 载体进行小胶质细胞靶向 NAMPT 过表达。将评估 NAMPT 对小胶质细胞髓磷脂吞噬作用、少突胶质细胞生成、WMI 和缺血后功能结果的影响。 PHS 398/2590（修订版 06/09）页面延续格式页面