Long-term effects of wildtype huntingtin lowering in the primate corticostriatal tract and thalamus

野生型亨廷顿蛋白降低对灵长类皮质纹状体束和丘脑的长期影响

• 批准号: 10610825
• 负责人: HEATHER A BOGER
• 金额: $ 56.57万
• 依托单位: UNIVERSITY OF KENTUCKY
• 依托单位国家: 美国
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-04-01 至 2025-03-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10610825
• 关键词: Adult; Affect; Age; Alleles; Animals; Autopsy; Axon; Behavior; Behavioral; Biosensor; Blinded; Brain; Brain region; Brain-Derived Neurotrophic Factor; Calcinosis; Calcium; Clinical Treatment; Clinical Trials; Collection; Corpus striatum structure; Data; Deposition; Development; Disease; Disease Progression; Dopamine; Evaluation; Future; Future Generations; Genes; Glutamates; Health; Health Status; Histology; Human; Huntington Disease; Huntington gene; Infusion procedures; Injections; Intervention; Knowledge; Long-Term Effects; Macaca mulatta; Magnetic Resonance Imaging; Measurement; Measures; Methods; Molecular; Monitor; Monkeys; Motor Activity; Mus; Nature; Neurodegenerative Disorders; Neurologic; Neurological status; Neurons; Neurotransmitters; Participant; Pathology; Patients; Periodicals; Primates; Production; Randomized; Reporting; Research; Resolution; Route; Serotyping; Structure; System; Thalamic structure; Time; Tissues; Treatment Efficacy; brain tissue; calcification; clinically significant; conditional knockout; end stage disease; experimental group; glutamatergic signaling; in vivo; mouse model; mutant; neuropathology; nonhuman primate; protein expression; putamen; retrograde transport; small hairpin RNA; therapeutic target; therapy adverse effect; tool; uptake; vector

PROJECT SUMMARY / ABSTRACT Most huntingtin-lowering treatments in development or clinical trials are not selective for the mutant allele, but also lower wildtype huntingtin expression. The purpose of this project is to fill critical gaps in our knowledge about the effects of wildtype huntingtin lowering in the primate brain over an extended period of time in brain regions relevant to Huntington’s disease (HD) and to the functions of wildtype huntingtin. Data from mouse models of HD indicate that lowering huntingtin in cortical neurons that are part of the corticostriatal system may be necessary for optimal therapeutic efficacy.1-3 Although prior research has established that lowering wildtype huntingtin by 45% in the primate striatum is well-tolerated for six months,4 this and other research5 has not lowered wildtype huntingtin in primate corticostriatal neurons whose axons comprise the corticostriatal tract. Huntingtin is involved in the rate of production6 and transport7 of BDNF (brain-derived neurotrophic factor) from cortical neurons to the striatum, on which striatal neurons depend.8 It is unknown whether reduction of wildtype huntingtin in corticostriatal neurons/tract of the primate brain will adversely affect the survival and functioning of striatal neurons. AIM 1 will assess the long-term tolerability of wildtype huntingtin lowering in the corticostriatal tract over 9 months by quantitatively measuring the effects of this lowering on locomotor activity, BDNF levels and neurotransmitter systems. As research tools, the project uses an shRNA already known to lower huntingtin in the primate4 and a serotype of AAV already known to retrogradely transduce cortical neurons from a striatal point of infusion.9 Treatment of the thalamus has been proposed as a means of enhancing vector distribution in the brain16. However, pathologic calcification of the thalamus has been reported in mice 9 months after partial, conditional knockout of wildtype huntingtin.10 AIM 2 will determine if reduction of wildtype huntingtin in the primate thalamus will result in an increased thalamic calcium accumulation, whether occurring incidentally from striatal infusion of vectors or directly by vector infusion targeting the thalamus. In the proposed studies, thirty- two (32) adult rhesus monkeys will be equally divided into four experimental groups (N= 8 animals/group) and randomly assigned to receive MRI-guided injections of AAV6 encoding a huntingtin-lowering shRNA or a control shRNA, directly into either the striatum (AIM 1) or thalamus (AIM 2). Monkeys will be assessed by periodic behavioral and neurological exams. In vivo glutamate signaling in the cortex, striatum and thalamus will be assessed 9 months after AAV administration. Post-mortem analysis will include assessments of dopamine turnover and BDNF levels in striatal tissue as well as calcium in the thalamus and neuropathological evaluations of coronal brain sections, including cortex, striatum and thalamus. The data obtained by this project in the nonhuman primate will provide information that cannot be readily obtained from human clinical trials of huntingtin-lowering treatments. This information will be pertinent to any current and future therapies for HD that use non-allele-specific means to lower huntingtin irrespective of the agent or route of delivery.

项目概要/摘要 大多数开发或临床试验中的亨廷顿蛋白降低治疗对突变等位基因没有选择性，但 也降低野生型亨廷顿蛋白表达。该项目的目的是填补我们知识方面的关键空白 关于野生型亨廷顿蛋白在灵长类动物大脑中长时间降低的影响 与亨廷顿病（HD）和野生型亨廷顿蛋白功能相关的区域。来自鼠标的数据 HD 模型表明，降低皮质纹状体系统一部分的皮质神经元中的亨廷顿蛋白可能 是获得最佳治疗效果所必需的。1-3 尽管先前的研究已证实降低野生型 灵长类纹状体中 45% 的亨廷顿蛋白在六个月内具有良好的耐受性，4 这项研究和其他研究 5 并未 灵长类皮质纹状体神经元的野生型亨廷顿蛋白降低，其轴突构成皮质纹状体束。 亨廷顿蛋白参与 BDNF（脑源性神经营养因子）的产生速率 6 和运输 7 皮层神经元到纹状体，纹状体神经元依赖纹状体。8 野生型的减少是否会减少尚不清楚 灵长类动物大脑皮质纹状体神经元/束中的亨廷顿蛋白会对神经元的生存和功能产生不利影响 纹状体神经元。 AIM 1 将评估野生型亨廷顿蛋白降低皮质纹状体的长期耐受性 通过定量测量这种降低对运动活动、BDNF 水平的影响，在 9 个月内进行治疗 和神经递质系统。作为研究工具，该项目使用已知可降低亨廷顿蛋白的 shRNA 在灵长类动物4中，AAV血清型已知可以从纹状体逆行转导皮质神经元 9 丘脑治疗已被提议作为增强载体分布的一种手段 大脑 16.然而，据报道，小鼠在部分、 野生型亨廷顿蛋白的条件性敲除。10 AIM 2 将确定是否减少野生型亨廷顿蛋白 灵长类丘脑会导致丘脑钙积累增加，无论是偶然发生的 纹状体输注载体或直接通过载体输注靶向丘脑。在拟议的研究中，三十 将两（32）只成年恒河猴平均分为四个实验组（N = 8只动物/组）并且 随机分配接受 MRI 引导的 AAV6 注射，该 AAV6 编码降低亨廷顿蛋白的 shRNA 或 控制 shRNA，直接进入纹状体 (AIM 1) 或丘脑 (AIM 2)。猴子将被评估 定期行为和神经学检查。皮质、纹状体和丘脑的体内谷氨酸信号传导 将在 AAV 给药后 9 个月进行评估。事后分析将包括评估 纹状体组织中的多巴胺周转率和 BDNF 水平以及丘脑中的钙和神经病理学 冠状脑切片的评估，包括皮质、纹状体和丘脑。由此得到的数据 非人类灵长类动物的项目将提供无法从人类临床中轻易获得的信息 降低亨廷顿蛋白治疗的试验。该信息将与任何当前和未来的治疗相关 HD 使用非等位基因特异性方法来降低亨廷顿蛋白，无论药物或递送途径如何。