AAV1.NT-3 gene therapy in the SOD1KO mouse model of accelerated sarcopenia

IF 8.9 1区医学

Journal of Cachexia, Sarcopenia and Muscle Pub Date : 2023-08-08 DOI:10.1002/jcsm.13303

Lingying Tong, Burcak Ozes, Kyle Moss, Morgan Myers, Alicia Ridgley, Zarife Sahenk

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引用次数: 1

Abstract

Background

Sarcopenia, an age-related loss of muscle mass, is a critical factor that affects the health of the older adults. The SOD1KO mouse is deficient of Cu/Zn superoxide dismutase, used as an accelerated aging model. We previously showed that NT-3 improves muscle fibre size by activating the mTOR pathway, suggesting a potential for attenuating age-related muscle loss. This study assessed the therapeutic efficacy of AAV1.NT-3 in this accelerated aging model.

Methods

Twelve 6 months old SOD1KO mice were injected intramuscularly with a 1 × 10¹¹ vg dose of AAV1.tMCK.NT-3, and 13 age-matched SOD1KO mice were used as controls. The treatment effect was evaluated using treadmill, rotarod and gait analyses as well as histological studies assessing changes in muscle fibre, and fibre type switch, in tibialis anterior, gastrocnemius, and triceps muscles, and myelin thickness by calculating G ratio in sciatic and tibial nerves. Molecular studies involved qPCR experiments to analyse the expression levels of mitochondrial and glycolysis markers and western blot experiments to assess the activity of mTORC1 pathway.

Results

Treatment resulted in a 36% (154.9 vs. 114.1; P < 0.0001) and 76% increase (154.3 vs. 87.6; P < 0.0001) in meters ran, with treadmill test at 3 and 6 months post gene delivery. In addition, the treated cohort stayed on rotarod 30% (52.7 s vs. 40.4 s; P = 0.0095) and 54% (50.4 s vs. 32.7 s; P = 0.0007) longer, compared with untreated counterparts at 3 and 6 months post injection. Gait analysis, performed at endpoint, showed that stride width was normalized to wild type levels (29.3 mm) by an 11% decrease, compared with untreated cohort (28.6 mm vs. 32.1 mm; P = 0.0014). Compared with wild-type, SOD1KO mice showed 9.4% and 11.4% fibre size decrease in tibialis anterior and gastrocnemius muscles, respectively, which were normalized to wild type levels with treatment. Fibre diameter increase was observed prominently in FTG fibre type. G ratio analysis revealed hypomyelination in the tibial (0.721) and sciatic (0.676) nerves of SOD1KO model, which was reversed in the NT-3 cohort (0.646 and 0.634, respectively). Fibre size increase correlated with the increase in the p-S6 and p-4E-BP1 levels, and in the glycolysis markers in tibialis anterior. Alterations observed in the mitochondrial markers were not rescued with treatment. Overall, response to NT-3 was subdued in gastrocnemius muscle.

Conclusions

This study shows that AAV1.NT-3 gene therapy protected SOD1KO mouse from accelerated aging effects functionally and histologically. We further confirmed that NT-3 has potential to activate the mTOR and glycolytic pathways in muscle.

Abstract Image

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AAV1.NT-3基因治疗加速少肌症SOD1KO小鼠模型。

背景：肌肉萎缩是一种与年龄相关的肌肉质量损失，是影响老年人健康的关键因素。SOD1KO小鼠缺乏Cu/Zn超氧化物歧化酶，用作加速衰老模型。我们之前表明，NT-3通过激活mTOR途径改善肌肉纤维大小，这表明它有可能减轻与年龄相关的肌肉损失。本研究评估了AAV1.NT-3在这种加速衰老模型中的治疗效果。方法：12只6个月大的SOD1KO小鼠肌肉注射1×1011vg剂量的AAV1.tMCK.NT-3，13只年龄匹配的SOD1KO小鼠作为对照。使用跑步机、旋转杆和步态分析以及组织学研究来评估治疗效果，通过计算坐骨神经和胫骨神经的G比率来评估胫骨前肌、腓肠肌和三头肌的肌肉纤维和纤维类型转换的变化，以及髓鞘厚度。分子研究包括qPCR实验来分析线粒体和糖酵解标志物的表达水平，以及蛋白质印迹实验来评估mTORC1通路的活性。结果：治疗导致36%（154.9 vs.114.1；P结论：本研究表明，AAV1.NT-3基因治疗在功能和组织学上保护SOD1KO小鼠免受加速衰老的影响。我们进一步证实，NT-3有可能激活肌肉中的mTOR和糖酵解途径。

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来源期刊

Journal of Cachexia, Sarcopenia and Muscle Medicine-Orthopedics and Sports Medicine

自引率

12.40%

发文量

期刊介绍： The Journal of Cachexia, Sarcopenia, and Muscle is a prestigious, peer-reviewed international publication committed to disseminating research and clinical insights pertaining to cachexia, sarcopenia, body composition, and the physiological and pathophysiological alterations occurring throughout the lifespan and in various illnesses across the spectrum of life sciences. This journal serves as a valuable resource for physicians, biochemists, biologists, dieticians, pharmacologists, and students alike.