Edinburgh Medical School: Biomedical Sciences, University of Edinburgh, Edinburgh, UK.
Euan MacDonald Centre for Motor Neuron Disease Research, Edinburgh, UK.
Neuropathol Appl Neurobiol. 2023 Aug;49(4):e12925. doi: 10.1111/nan.12925.
Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease with complex aetiology. Despite evidence of neuromuscular junction (NMJ) denervation and 'dying-back' pathology in models of SOD1-dependent ALS, evidence in other genetic forms of ALS is limited by a lack of suitable animal models. TDP-43, a key mediator protein in ALS, is overexpressed in neurons in Thy1-hTDP-43 mice. We therefore aimed to comprehensively analyse NMJ pathology in this model of ALS.
Expression of TDP-43 was assessed via western blotting. Immunohistochemistry techniques, alongside NMJ-morph quantification, were used to analyse motor neuron number, NMJ denervation status and terminal Schwann cell morphology.
We present a time course of progressive, region-specific motor neuron pathology in Thy1-hTDP-43 mice. Thy1-driven hTDP-43 expression increased steadily, correlating with developing hindlimb motor weakness and associated motor neuron loss in the spinal cord with a median survival of 21 days. Pronounced NMJ denervation was observed in hindlimb muscles, mild denervation in cranial muscles but no evidence of denervation in either forelimb or trunk muscles. NMJ pathology was restricted to motor nerve terminals, with denervation following the same time course as motor neuron loss. Terminal Schwann cells were lost from NMJs in hindlimb muscles, directly correlating with denervation status.
Thy1-hTDP-43 mice represent a severe model of ALS, with NMJ pathology/denervation of distal muscles and motor neuron loss, as observed in ALS patients. This model therefore provides an ideal platform to investigate mechanisms of dying-back pathology, as well as NMJ-targeting disease-modifying therapies in ALS.
肌萎缩侧索硬化症（ALS）是一种具有复杂病因的致命神经退行性疾病。尽管在 SOD1 依赖性 ALS 的模型中已经有证据表明神经肌肉接头（NMJ）去神经支配和“退行性”病理学，但在其他遗传形式的 ALS 中，由于缺乏合适的动物模型，证据有限。TDP-43 是 ALS 中的关键中介蛋白，在 Thy1-hTDP-43 小鼠的神经元中过度表达。因此，我们旨在全面分析该 ALS 模型中的 NMJ 病理学。
通过 Western blot 评估 TDP-43 的表达。使用免疫组织化学技术以及 NMJ 形态定量分析，分析运动神经元数量、NMJ 去神经支配状态和末端 Schwann 细胞形态。
我们展示了 Thy1-hTDP-43 小鼠中进行性、区域特异性运动神经元病理学的时间进程。Thy1 驱动的 hTDP-43 表达稳步增加，与后肢运动无力相关，并伴有脊髓运动神经元丢失，中位生存时间为 21 天。在后肢肌肉中观察到明显的 NMJ 去神经支配，在前肢或躯干肌肉中则观察到轻度去神经支配，但在任何前肢或躯干肌肉中均未观察到去神经支配。NMJ 病理学仅限于运动神经末梢，去神经支配与运动神经元丢失具有相同的时间进程。末端 Schwann 细胞从后肢肌肉的 NMJ 中丢失，与去神经支配状态直接相关。
Thy1-hTDP-43 小鼠代表了一种严重的 ALS 模型，具有 NMJ 病理学/远端肌肉去神经支配和运动神经元丢失，这与 ALS 患者的情况相似。因此，该模型为研究退行性病理的机制以及针对 NMJ 的疾病修饰治疗 ALS 提供了理想的平台。
