Understanding the Mechanism and Preventing the Unique Neuropathology of Arginase Deficiency

了解精氨酸酶缺乏的机制并预防独特的神经病理学

• 批准号: 10080755
• 负责人: Gerald S Lipshutz
• 金额: $ 34.13万
• 依托单位: UNIVERSITY OF CALIFORNIA LOS ANGELES
• 依托单位国家: 美国
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-04-15 至 2023-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10080755
• 关键词: Acids; Acute; Address; Adoption; Anatomy; Animals; Arginine; Birth; Brain; Bystander Effect; Cells; Cerebral cortex; Cessation of life; Chronic; Clinical; Clinical Trials; Congenital neurologic anomalies; Creatine; Data; Disease; Electrophysiology (science); Enzymes; Etiology; Exposure to; Failure to Thrive; Functional disorder; Gene Expression; Goals; Growth; Health; Hepatic; Hyperammonemia; Hyperargininemia; Impairment; Inborn Errors of Metabolism; Inequality; Interneurons; Intervention; Knock-out; Knockout Mice; Laboratories; Life; Liver; Measurable; Measures; Mediating; Metabolism; Microcephaly; Motor; Mus; Myelin; Neonatal; Nervous System Trauma; Neuraxis; Neurologic; Neuronal Dysfunction; Neuronal Injury; Neurons; Oligodendroglia; Pathogenesis; Patients; Periodicity; Peripheral; Pharmacology; Plasma; Play; Psyche structure; Recombinant adeno-associated virus (rAAV); Research; Resolution; Role; Seizures; Slice; Synapses; Synaptic Transmission; Taurine; Testing; Toxin; Urea cycle disorders; arginase; base; central nervous system injury; density; dysmyelination; excitatory neuron; experimental study; gene therapy; improved; infancy; knockout animal; leukodystrophy; mouse model; myelination; nervous system disorder; neuropathology; novel therapeutics; patch clamp; postnatal; prevent; response; restoration; spasticity; transmission process; urea cycle

Project Summary/Abstract The overall goals of this project are to 1) investigate the etiology of the unique neuropathology associated with arginase 1 (A1) deficiency, a disorder of the urea cycle, and 2) to extensively demonstrate that AAV-based hepatic gene therapy is effective in preventing the features of this disorder as a prelude to a clinical trial. A1 deficiency results in chronic hyperargininemia characterized by progressive mental impairment, spasticity, and growth retardation, with only periodic episodes of hyperammonemia. Recent and preliminary findings from our laboratory with the A1-deficient mouse have demonstrated substantial anatomical, ultrastructural and electro- physiological differences between knockouts and wild types. A1 deficiency led to decreased intrinsic excita- bility, altered functional synaptic transmission, decreased dendritic arborization, dysmyelination and decreased synaptic density. The most likely mechanism causing these neuronal abnormalities is hyperarginine- or guani- dino compound-mediated dysfunction of neurons and oligodendrocytes. Controlling plasma arginine and guani- dino compounds following administration of liver-specific AAV-based gene therapy resulted in much of these measures being substantially improved. The finding abnormalities at the neuron, synapse, myelin, and circuit level have begun to elucidate the functional deficits in A1 deficiency. The identification of the proximate toxin and mechanism of neurodysfunction will open doors to potential pharmacological interventions for A1 deficiency in addition to gene therapy, and may open avenues to new therapies for other disorders where dysmyelination is a feature. Preliminary data: Our research group has (amongst other findings): 1) constructed and characterized the A1-deficient mouse; 2) demonstrated long-term survival with liver-specific recombinant AAV; 3) demonstrated that only low-level ureagenesis is necessary for survival; 4) shown that gene therapy- treated A1 knockout mice lack gross nervous system abnormalities; 5) shown that peripheral metabolism results in control of circulating plasma arginine; and 6) shown that loss of A1 gene expression results in abnormalities of intrinsic excitability, synapse type and number, myelination and the dendritic arbor of neurons. In Aim 1, the hypothesis that oligodendrocyte dysfunction and death result in dysmyelination and is in part the cause of neuronal dysfunction in A1 deficiency will be tested. In Aim 2, the hypothesis that elevated guanidino compounds can induce alterations in intrinsic excitability and synaptic transmission that are similar to those seen in A1 deficient animals will be tested. In Aim 3, it will be determined if A1 deficiency causes an imbalance in excitation and inhibition, and if this inequality is mainly through effects on perisomatic inhibition. Completion of these studies will provide a greater understanding of and the mechanism(s) behind the alterations in the brain, neurons, and synapses in A1 deficiency and hyperargininemia while demonstrating the efficacy of hepatic A1 gene therapy in preventing these abnormalities, providing strong evidence for this therapy as a prelude to its clinical adoption in patients with this progressive neurological disorder.

项目概要/摘要 该项目的总体目标是 1) 研究与以下疾病相关的独特神经病理学的病因学： 精氨酸酶 1 (A1) 缺乏症，一种尿素循环障碍，以及 2) 广泛证明基于 AAV 的 作为临床试验的前奏，肝脏基因治疗可有效预防这种疾病的特征。 A1 缺乏会导致慢性高精氨酸血症，其特征是进行性精神障碍、痉挛和 生长迟缓，仅伴有周期性高氨血症。我们的最新和初步调查结果 实验室对 A1 缺陷小鼠的研究已经证明了其显着的解剖学、超微结构和电学特征。 敲除型和野生型之间的生理差异。 A1 缺乏导致内在兴奋性下降 能力、功能性突触传递改变、树突分枝减少、髓鞘形成障碍和减少 突触密度。导致这些神经元异常的最可能的机制是高精氨酸或鸟嘌呤 恐龙化合物介导的神经元和少突胶质细胞功能障碍。控制血浆精氨酸和鸟嘌呤 施用基于肝脏特异性 AAV 的基因治疗后的恐龙化合物导致了其中大部分 措施明显完善。发现神经元、突触、髓磷脂和回路异常 水平已开始阐明 A1 缺乏症的功能缺陷。邻近毒素的鉴定 神经功能障碍的机制将为 A1 的潜在药物干预打开大门 除了基因疗法之外，还可能为其他疾病的新疗法开辟途径 髓鞘发育不良是一个特征。初步数据：我们的研究小组（除其他发现外）：1）构建 并对 A1 缺陷小鼠进行了表征； 2) 证明肝脏特异性重组可以长期存活 腺病毒； 3）证明只有低水平的尿素生成对于生存是必要的； 4）表明基因治疗- 经治疗的 A1 基因敲除小鼠缺乏明显的神经系统异常； 5)表明外周代谢 控制循环血浆精氨酸的结果；和 6) 表明 A1 基因表达缺失会导致 内在兴奋性、突触类型和数量、髓鞘形成和神经元树突状结构的异常。 在目标 1 中，假设少突胶质细胞功能障碍和死亡导致髓鞘形成障碍，并且部分是 将测试 A1 缺乏症神经元功能障碍的原因。在目标 2 中，假设提高胍基 化合物可以诱导内在兴奋性和突触传递的改变，类似于那些 在 A1 缺陷动物中观察到的情况将进行测试。在目标 3 中，将确定 A1 缺乏是否会导致失衡 兴奋和抑制，如果这种不平等主要是通过对体周抑制的影响。完成 这些研究将提供对这些变化背后的机制的更深入的了解 A1 缺乏症和高精氨酸血症中的大脑、神经元和突触，同时证明了 肝 A1 基因疗法可以预防这些异常，为该疗法作为一种治疗方法提供了强有力的证据。 为这种进行性神经系统疾病患者的临床采用奠定了基础。