Department of Neuromuscular Disease, UCL Queen Square Institute of Neurology, Queen Square, London, WC1N 3BG, UK.
The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK.
Brain. 2020 Feb 1;143(2):430-440. doi: 10.1093/brain/awz419.
Amyotrophic lateral sclerosis (ALS) is a fatal and incurable neurodegenerative disease caused by motor neuron loss, resulting in muscle wasting, paralysis and eventual death. A key pathological feature of ALS is cytoplasmically mislocalized and aggregated TDP-43 protein in >95% of cases, which is considered to have prion-like properties. Historical studies have predominantly focused on genetic forms of ALS, which represent ∼10% of cases, leaving the remaining 90% of sporadic ALS relatively understudied. Additionally, the role of astrocytes in ALS and their relationship with TDP-43 pathology is also not currently well understood. We have therefore used highly enriched human induced pluripotent stem cell (iPSC)-derived motor neurons and astrocytes to model early cell type-specific features of sporadic ALS. We first demonstrate seeded aggregation of TDP-43 by exposing human iPSC-derived motor neurons to serially passaged sporadic ALS post-mortem tissue (spALS) extracts. Next, we show that human iPSC-derived motor neurons are more vulnerable to TDP-43 aggregation and toxicity compared with their astrocyte counterparts. We demonstrate that these TDP-43 aggregates can more readily propagate from motor neurons into astrocytes in co-culture paradigms. We next found that astrocytes are neuroprotective to seeded aggregation within motor neurons by reducing (mislocalized) cytoplasmic TDP-43, TDP-43 aggregation and cell toxicity. Furthermore, we detected TDP-43 oligomers in these spALS spinal cord extracts, and as such demonstrated that highly purified recombinant TDP-43 oligomers can reproduce this observed cell-type specific toxicity, providing further support to a protein oligomer-mediated toxicity hypothesis in ALS. In summary, we have developed a human, clinically relevant, and cell-type specific modelling platform that recapitulates key aspects of sporadic ALS and uncovers both an initial neuroprotective role for astrocytes and the cell type-specific toxic effect of TDP-43 oligomers.
肌萎缩侧索硬化症（ALS）是一种由运动神经元丧失引起的致命和不可治愈的神经退行性疾病，导致肌肉萎缩、瘫痪和最终死亡。ALS 的一个关键病理学特征是细胞质中错误定位和聚集的 TDP-43 蛋白，在超过 95%的病例中，这被认为具有朊病毒样特性。历史研究主要集中在 ALS 的遗传形式上，这代表了约 10%的病例，而其余 90%的散发性 ALS 相对研究不足。此外，星形胶质细胞在 ALS 中的作用及其与 TDP-43 病理学的关系目前也不太清楚。因此，我们使用高度富集的人诱导多能干细胞（iPSC）衍生的运动神经元和星形胶质细胞来模拟散发性 ALS 的早期细胞类型特异性特征。我们首先证明通过将人 iPSC 衍生的运动神经元暴露于连续传代的散发性 ALS 死后组织（spALS）提取物中，可以引发 TDP-43 的聚集。接下来，我们表明与星形胶质细胞相比，人 iPSC 衍生的运动神经元对 TDP-43 聚集和毒性更敏感。我们证明这些 TDP-43 聚集体可以更容易地从运动神经元传播到共培养模型中的星形胶质细胞中。接下来，我们发现星形胶质细胞通过减少（错误定位的）细胞质 TDP-43、TDP-43 聚集和细胞毒性对运动神经元中的种子聚集具有神经保护作用。此外，我们在这些 spALS 脊髓提取物中检测到 TDP-43 低聚物，因此证明了高度纯化的重组 TDP-43 低聚物可以重现观察到的细胞类型特异性毒性，为 ALS 中的蛋白低聚物介导的毒性假说提供了进一步支持。总之，我们开发了一种具有临床相关性的人类细胞类型特异性建模平台，该平台再现了散发性 ALS 的关键方面，并揭示了星形胶质细胞的初始神经保护作用以及 TDP-43 低聚物的细胞类型特异性毒性作用。
