Combined neuroprotection and metabolic correction to treat leukodystrophies

联合神经保护和代谢校正治疗脑白质营养不良

基本信息

批准号：
8131096
负责人：
Ernesto Roque Bongarzone
金额：
$ 33.16万
依托单位：
UNIVERSITY OF ILLINOIS AT CHICAGO
依托单位国家：
美国
项目类别：
财政年份：
2009
资助国家：
美国
起止时间：
2009-09-01 至 2014-08-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8131096
关键词：
Address Affect Alzheimer&apos s Disease Animal Model Anti-Arrhythmia Agents Axon Axonal Transport Binding Biochemical Biological Assay Birth Blood - brain barrier anatomy Bone Marrow Cell Transplantation Bone Marrow Transplantation Brain Calcium Cells Childhood Clinical Complement Complex Confocal Microscopy Consensus Defect Demyelinating Diseases Demyelinations Deterioration Development Diffusion Disease Ensure Enzymes Evaluation Flecainide Functional disorder Genetic Globoid cell leukodystrophy Hematogenous Homeostasis Human Imagery Individual Inherited Injection of therapeutic agent Intervention Intravenous Laboratories Life Light Link Lysosomal Storage Diseases Magnetic Resonance Imaging Mediating Metabolic Microscope Modeling Molecular Multiple Sclerosis Mus Myelin Nerve Nerve Degeneration Nervous system structure Neural Conduction Neurodegenerative Disorders Neuroglia Neurologic Neuronal Dysfunction Neurons Newborn Infant Nicotinic Receptors Outcome Parkinson Disease Pathogenesis Pathology Patients Pharmaceutical Preparations Protein phosphatase Psychosine Rabies virus Ranvier&apos s Nodes Role Small Interfering RNA Sodium Channel Structure Swelling Symptoms Testing Therapeutic Time Transgenic Organisms axonopathy base biological adaptation to stress design enzyme deficiency experience fast axonal transport galactosylceramidase improved in vivo insight leukodystrophy macrophage mutant myelination neuron loss neuroprotection novel novel therapeutics postnatal prevent public health relevance reconstitution research study therapeutic enzyme traditional therapy

项目摘要

DESCRIPTION (provided by applicant): Galactosylceramidase (GALC) deficiency in Krabbe disease (KD) causes toxic accumulation of galactosylsphingosine (psychosine) in myelin-forming cells, leading to demyelination of the nervous system. To reduce demyelination, current therapies seek to provide the missing enzyme to myelinating glia via infiltrating macrophages after the transplantation of bone marrow cells (BMT) from healthy donors into affected patients. Although the experience gained from this approach supports the use of BMT, KD patients suffer neurological sequelae. This suggests that the pathogenic mechanisms in KD are more complex than previously thought and that new therapeutic strategies are needed to cure KD. Experiments in our laboratory using the Twitcher mouse, a natural model for KD, indicate: 1) BMT- treated mice show neuronal and axonal damage by the time sufficient therapeutic enzyme accumulates in the nervous system [1]; 2) psychosine is also produced and accumulates in neurons in the absence of mutant glia, causing the blockage of fast axonal transport via the activity of protein phosphatase 1 (PP1); and 3) mutant neurons show abnormal intracellular levels of Ca linked to deregulated expression of the Na+ Ca exchanger (NCX1). These observations suggest that GALC-deficient neurons mount a stress response that contributes to the pathology and that PP1 and NCX1 are two potential key components in the mechanism that mediates axonal defects in KD. Thus, we hypothesize that the deficiency of GALC in KD not only affects myelination but also triggers intrinsic and contemporaneous defects in neurons. To test this hypothesis we propose specific experiments to modulate PP1 and NCX1 activities in Twitcher neurons. These experiments will provide proof-of-concept that neuroprotective strategies can synergize with/improve the therapeutic benefits of traditional BMT-based treatments. Specifically, we will: 1) determine whether controlled and specific reduction of neuronal PP1 activity using siRNA specific silencing protects axonal transport in mutant neurons; 2) determine whether flecainide, an antiarrhythmic drug with a proven ability to reduce sodium channel firing and NCX1 activity, improves NCX1-mediated influx of calcium in axons; and 3) determine whether these neuroprotective strategies combined with metabolic correction after BMT in newborn Twitcher mice improve clinical outcome. Results from these experiments will shed light on the molecular role of PP1 and NCX1 activity mediating neuronal dysfunction in KD and will provide a unique opportunity to improve the current BMT-based metabolic corrective strategies used to treat this leukodystrophy. The insight obtained will be relevant to other lysosomal storage disorders, which like KD are associated with aggressive neurological deterioration and for which there are no available cures. PUBLIC HEALTH RELEVANCE: Krabbe disease is a lysosomal storage disease that results in demyelination of the brain and nerves in affected individuals. Some Krabbe patients are treated with hematogenous cell replacement, which delays the onset of symptoms. However, a definitive and complete cure for this disease has not been achieved and treated patients continue to undergo deterioration and neurological deficits. The role of neuronal loss in Krabbe disease is not completely understood, but a consensus is emerging that dysfunction of axons and neurons leads to permanent neurological deficits in several neurodegenerative disorders, including multiple sclerosis, Alzheimer disease, Parkinson disease and others. Our preliminary studies provide evidence that Krabbe disease is compounded by axonal defects. In addition to the loss of myelin, neurodegeneration is likely a limiting factor in reducing the efficiency of traditional therapies. Thus, a combined therapy that provides not only enzyme replacement but also neuroprotection is likely to synergize or enhance the therapeutic benefits. Our objective is to examine whether two novel neuroprotective strategies targeting specific aspects of neurodegeneration in Krabbe disease can be combined with traditional bone marrow transplantation to fully prevent development of the disease. Results of the proposed experiments will provide proof-of-concept for the design of combined neuroprotective therapies to treat human Krabbe patients and the rational basis for studies of other leukodystrophies that involve degeneration of axons and myelin.

描述（由申请人提供）：Krabbe疾病（KD）中的半乳糖基酶酶（GALC）缺乏，导致髓磷脂形成细胞中半乳糖基肾上腺素（Psychosine）的毒性积累，从而导致神经系统脱髓鞘。为了减少脱髓鞘，当前的疗法试图通过渗透巨噬细胞向骨髓细胞（BMT）从健康供体移植到受影响的患者后，通过浸润巨噬细胞为髓鞘胶质细胞提供缺失的酶。尽管从这种方法获得的经验支持BMT的使用，但KD患者患有神经后遗症。这表明KD中的致病机制比以前认为的更为复杂，并且需要新的治疗策略来治愈KD。使用Twitcher小鼠（一种自然的KD模型）在我们实验室进行的实验表明：1）BMT处理的小鼠在时间上表现出神经元和轴突损伤，这是在神经系统中积累的足够的治疗酶[1]； 2）在没有突变神经胶质的情况下，还会产生心理素并在神经元中积聚，从而通过蛋白质磷酸酶1的活性（PP1）引起快速轴突转运的阻塞； 3）突变神经元显示出与Na+ Ca交换器不受调节表达相关的细胞内水平（NCX1）。这些观察结果表明，galc缺陷型神经元安装了有助于病理的应力反应，并且PP1和NCX1是介导KD中轴突缺陷的机制中的两个潜在的关键成分。因此，我们假设galc在KD中的缺乏不仅会影响髓鞘形成，而且还会触发神经元中的内在和同时缺陷。为了检验该假设，我们提出了特定的实验，以调节抽搐神经元中的PP1和NCX1活性。这些实验将提供概念证明，即神经保护策略可以与传统基于BMT的治疗的治疗益处协同/改善。具体而言，我们将：1）确定使用siRNA特异性沉默对神经元PP1活性的受控和特异性降低是否可以保护突变神经元中的轴突转运； 2）确定氟卡尼是一种抗心律失常药物，具有降低钠通道发射和NCX1活性的能力，可改善轴突中钙的NCX1介导的钙的流入； 3）确定这些神经保护策略是否与新生儿抽搐小鼠BMT后的代谢校正结合起来是否可以改善临床结果。这些实验的结果将阐明介导KD中神经元功能障碍的PP1和NCX1活性的分子作用，并将为改善用于治疗这种白细胞病的当前基于BMT的代谢纠正策略提供独特的机会。获得的洞察力将与其他溶酶体储存障碍有关，这些溶酶体储存障碍与KD一样与侵略性神经系统恶化有关，并且没有可用的治疗方法。公共卫生相关性：Krabbe病是一种溶酶体储存疾病，导致受影响个体的大脑和神经脱髓鞘。一些Krabbe患者接受血源性细胞置换治疗，这延迟了症状的发作。但是，尚未达到这种疾病的确定而完全治愈的治疗方法，并且治疗的患者继续发生恶化和神经缺陷。神经元丧失在Krabbe疾病中的作用尚不完全了解，但是达成共识的是，轴突和神经元的功能障碍导致多种神经退行性疾病的永久神经缺陷，包括多发性硬化症，阿尔茨海默氏病，帕金森氏病等。我们的初步研究提供了证据，表明克拉布疾病因轴突缺陷而复杂。除了失去髓磷脂外，神经变性可能是降低传统疗法效率的限制因素。因此，一种合并的疗法不仅提供酶替代酶，而且神经保护可能会协同或增强治疗益处。我们的目标是检查针对Krabbe疾病中神经退行性特定方面的两种新型神经保护策略是否可以与传统的骨髓移植相结合以完全防止疾病的发展。拟议的实验的结果将为设计综合治疗人Krabbe患者的组合设计提供概念概念，并为涉及轴突变性和髓磷脂变性的其他白细胞营养不良的研究的合理基础。