Human VCP mutant ALS/FTD microglia display immune and lysosomal phenotypes independently of GPNMB

Benjamin E Clarke; Oliver J Ziff; Giulia Tyzack; Marija Petrić Howe; Yiran Wang; Pierre Klein; Claudia A Smith; Cameron A Hall; Adel Helmy; Michael Howell; Gavin Kelly; Rickie Patani

doi:10.1186/s13024-024-00773-1

Human VCP mutant ALS/FTD microglia display immune and lysosomal phenotypes independently of GPNMB

Mol Neurodegener. 2024 Nov 26;19(1):90. doi: 10.1186/s13024-024-00773-1.

Authors

Benjamin E Clarke^#^{1

2}, Oliver J Ziff^#^{3

4

5}, Giulia Tyzack^{6

7}, Marija Petrić Howe^{6

7}, Yiran Wang^{6

7}, Pierre Klein^{6

7}, Claudia A Smith⁸, Cameron A Hall⁸, Adel Helmy⁸, Michael Howell⁷, Gavin Kelly⁷, Rickie Patani^{9

10

11}

Affiliations

¹ Department of Neuromuscular Diseases, Queen Square Institute of Neurology, University College London, London, WC1N 3BG, UK. [email protected].
² The Francis Crick Institute, 1 Midland Road, London, NW1 1AT, UK. [email protected].
³ Department of Neuromuscular Diseases, Queen Square Institute of Neurology, University College London, London, WC1N 3BG, UK. [email protected].
⁴ The Francis Crick Institute, 1 Midland Road, London, NW1 1AT, UK. [email protected].
⁵ National Hospital for Neurology and Neurosurgery, University College London NHS Foundation Trust, London, WC1N 3BG, UK. [email protected].
⁶ Department of Neuromuscular Diseases, Queen Square Institute of Neurology, University College London, London, WC1N 3BG, UK.
⁷ The Francis Crick Institute, 1 Midland Road, London, NW1 1AT, UK.
⁸ Division of Neurosurgery and Wolfson Brain Imaging Centre, Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK.
⁹ Department of Neuromuscular Diseases, Queen Square Institute of Neurology, University College London, London, WC1N 3BG, UK. [email protected].
¹⁰ The Francis Crick Institute, 1 Midland Road, London, NW1 1AT, UK. [email protected].
¹¹ National Hospital for Neurology and Neurosurgery, University College London NHS Foundation Trust, London, WC1N 3BG, UK. [email protected].

^# Contributed equally.

Abstract

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.

MeSH terms

Amyotrophic Lateral Sclerosis* / genetics
Amyotrophic Lateral Sclerosis* / metabolism
Amyotrophic Lateral Sclerosis* / pathology
Animals
Astrocytes / metabolism
Frontotemporal Dementia* / genetics
Frontotemporal Dementia* / metabolism
Frontotemporal Dementia* / pathology
Humans
Induced Pluripotent Stem Cells* / metabolism
Lysosomes* / metabolism
Membrane Glycoproteins* / genetics
Membrane Glycoproteins* / metabolism
Mice
Microglia* / metabolism
Motor Neurons / metabolism
Motor Neurons / pathology
Mutation / genetics
Phenotype
Valosin Containing Protein* / genetics
Valosin Containing Protein* / metabolism

Substances

Membrane Glycoproteins
Valosin Containing Protein
GPNMB protein, human
VCP protein, human