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Updated: Jun 6, 2025
Isolation of Cortical Microglia with Preserved Immunophenotype and Functionality From Murine Neonates
Published on: January 30, 2014
Human VCP mutant ALS/FTD microglia display immune and lysosomal phenotypes independently of GPNMB
Benjamin E Clarke1,2, Oliver J Ziff3,4,5, Giulia Tyzack6,7
1Department of Neuromuscular Diseases, Queen Square Institute of Neurology, University College London, London, WC1N 3BG, UK. ben.clarke@crick.ac.uk.
Background:
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.
Methods:
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.
Results:
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.
Conclusions:
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.
Insights
VCP mutant microglia show immune and lysosomal dysfunction in ALS/FTD. These cells impact motor neurons and astrocytes via the JAK-STAT pathway, independent of GPNMB.
Area of Science:
- Neuroscience
- Immunology
- Genetics
Background:
- Microglia are vital for brain health but implicated in ALS and FTD.
- The precise function of microglia in ALS/FTD pathogenesis is not fully understood.
Purpose of the Study:
- To investigate the cell-autonomous and non-cell-autonomous roles of VCP mutant microglia in ALS pathogenesis using human induced pluripotent stem cells (hiPSCs).
Main Methods:
- Generated hiPSC-derived VCP mutant microglia cultures.
- Utilized RNA-sequencing, proteomics, and functional assays.
- Examined effects on hiPSC-derived motor neurons and astrocytes.
Main Results:
- VCP mutant microglia exhibit immune and lysosomal dysfunction.
- These cells show partial overlap with LPS-stimulated microglia but distinct inflammatory pathway activation.
- Conserved gene expression changes noted across VCP mutant microglia, SOD1 mutant mouse microglia, and postmortem ALS tissue.
- Secreted factors from VCP mutant microglia activate the JAK-STAT pathway in motor neurons and astrocytes.
Conclusions:
- VCP mutant microglia undergo cell-autonomous reactive transformation with immune and lysosomal dysfunction, recapitulating ALS phenotypes.
- These changes occur independently of GPNMB.
- VCP mutant microglia induce non-cell-autonomous responses in motor neurons and astrocytes via the JAK-STAT pathway.
