Department of Neuromuscular Diseases, Queen Square Institute of Neurology, University College London, London, WC1N 3BG, UK.
The Francis Crick Institute, 1 Midland Road, London, NW1 1AT, UK.
Mol Neurodegener. 2024 Nov 26;19(1):90. doi: 10.1186/s13024-024-00773-1.
Microglia play crucial roles in maintaining neuronal homeostasis but have been implicated in contributing to amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). However, the role of microglia in ALS/FTD remains incompletely understood.
Here, we generated highly enriched cultures of VCP mutant microglia derived from human induced pluripotent stem cells (hiPSCs) to investigate their cell autonomous and non-cell autonomous roles in ALS pathogenesis. We used RNA-sequencing, proteomics and functional assays to study hiPSC derived VCP mutant microglia and their effects on hiPSC derived motor neurons and astrocytes.
Transcriptomic, proteomic and functional analyses revealed immune and lysosomal dysfunction in VCP mutant microglia. Stimulating healthy microglia with the inflammatory inducer lipopolysaccharide (LPS) showed partial overlap with VCP mutant microglia in their reactive transformation. LPS-stimulated VCP mutant microglia displayed differential activation of inflammatory pathways compared with LPS-stimulated healthy microglia. Conserved gene expression changes were identified between VCP mutant microglia, SOD1 mutant mice microglia, and postmortem ALS spinal cord microglial signatures, including increased expression of the transmembrane glycoprotein GPNMB. While knockdown of GPNMB affected inflammatory and phagocytosis processes in microglia, this was not sufficient to ameliorate cell autonomous phenotypes in VCP mutant microglia. Secreted factors from VCP mutant microglia were sufficient to activate the JAK-STAT pathway in hiPSC derived motor neurons and astrocytes.
VCP mutant microglia undergo cell autonomous reactive transformation involving immune and lysosomal dysfunction that partially recapitulate key phenotypes of microglia from other ALS models and post mortem tissue. These phenotypes occur independently of GPNMB. Additionally, VCP mutant microglia elicit non cell autonomous responses in motor neurons and astrocytes involving the JAK-STAT pathway.
小胶质细胞在维持神经元内稳态方面发挥着关键作用，但也被认为与肌萎缩侧索硬化症（ALS）和额颞叶痴呆（FTD）有关。然而，小胶质细胞在 ALS/FTD 中的作用仍不完全清楚。
在这里，我们从人类诱导多能干细胞（hiPSC）中生成了高度富集的 VCP 突变小胶质细胞培养物，以研究它们在 ALS 发病机制中的细胞自主和非细胞自主作用。我们使用 RNA 测序、蛋白质组学和功能测定来研究 hiPSC 衍生的 VCP 突变小胶质细胞及其对 hiPSC 衍生的运动神经元和星形胶质细胞的影响。
转录组、蛋白质组和功能分析显示 VCP 突变小胶质细胞存在免疫和溶酶体功能障碍。用炎性诱导剂脂多糖（LPS）刺激健康小胶质细胞显示出与 VCP 突变小胶质细胞在反应性转化中的部分重叠。与 LPS 刺激的健康小胶质细胞相比，LPS 刺激的 VCP 突变小胶质细胞显示出炎症途径的差异激活。在 VCP 突变小胶质细胞、SOD1 突变小鼠小胶质细胞和死后 ALS 脊髓小胶质细胞特征之间，鉴定到保守的基因表达变化，包括跨膜糖蛋白 GPNMB 的表达增加。虽然 GPNMB 的敲低影响小胶质细胞中的炎症和吞噬过程，但这不足以改善 VCP 突变小胶质细胞中的细胞自主表型。VCP 突变小胶质细胞分泌的因子足以激活 hiPSC 衍生的运动神经元和星形胶质细胞中的 JAK-STAT 通路。
VCP 突变小胶质细胞经历细胞自主的反应性转化，涉及免疫和溶酶体功能障碍，部分再现了其他 ALS 模型和死后组织中小胶质细胞的关键表型。这些表型独立于 GPNMB 发生。此外，VCP 突变小胶质细胞在运动神经元和星形胶质细胞中引发非细胞自主反应，涉及 JAK-STAT 通路。
