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Updated: Jun 14, 2026
Primary Cultures of Rat Astrocytes and Microglia and Their Use in the Study of Amyotrophic Lateral Sclerosis
Published on: June 23, 2022
C9orf72-ALS human iPSC microglia are pro-inflammatory and toxic to co-cultured motor neurons via MMP9
Björn F Vahsen1,2, Sumedha Nalluru1, Georgia R Morgan1
1Oxford Motor Neuron Disease Centre, Nuffield Department of Clinical Neurosciences, University of Oxford, John Radcliffe Hospital, Oxford, OX3 9DU, UK.
Abstract:
Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease characterized by progressive motor neuron loss, with additional pathophysiological involvement of non-neuronal cells such as microglia. The commonest ALS-associated genetic variant is a hexanucleotide repeat expansion (HRE) mutation in C9orf72. Here, we study its consequences for microglial function using human iPSC-derived microglia. By RNA-sequencing, we identify enrichment of pathways associated with immune cell activation and cyto-/chemokines in C9orf72 HRE mutant microglia versus healthy controls, most prominently after LPS priming. Specifically, LPS-primed C9orf72 HRE mutant microglia show consistently increased expression and release of matrix metalloproteinase-9 (MMP9). LPS-primed C9orf72 HRE mutant microglia are toxic to co-cultured healthy motor neurons, which is ameliorated by concomitant application of an MMP9 inhibitor. Finally, we identify release of dipeptidyl peptidase-4 (DPP4) as a marker for MMP9-dependent microglial dysregulation in co-culture. These results demonstrate cellular dysfunction of C9orf72 HRE mutant microglia, and a non-cell-autonomous role in driving C9orf72-ALS pathophysiology in motor neurons through MMP9 signaling.
Insights
Amyotrophic lateral sclerosis (ALS) involves motor neuron loss and microglial dysfunction. C9orf72 mutation causes microglia to release MMP9, harming motor neurons, a key factor in ALS.
Area of Science:
- Neuroscience
- Immunology
- Genetics
Background:
- Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease with motor neuron loss.
- Microglia, immune cells in the brain, are implicated in ALS pathology.
- The C9orf72 hexanucleotide repeat expansion (HRE) is the most common genetic cause of ALS.
Purpose of the Study:
- To investigate the functional consequences of the C9orf72 HRE mutation on human microglia.
- To determine the role of C9orf72-mutant microglia in ALS pathogenesis.
Main Methods:
- Utilized human induced pluripotent stem cell (iPSC)-derived microglia.
- Performed RNA-sequencing to analyze gene expression changes.
- Co-cultured microglia with motor neurons and assessed neuronal survival.
Main Results:
- C9orf72 HRE mutant microglia exhibit heightened immune activation pathways, especially after LPS priming.
- Increased expression and release of matrix metalloproteinase-9 (MMP9) by LPS-primed mutant microglia.
- Mutant microglia are toxic to motor neurons, a toxicity reduced by MMP9 inhibition.
Conclusions:
- C9orf72 HRE mutation leads to microglial cellular dysfunction.
- Dysfunctional microglia contribute to ALS pathophysiology through MMP9-mediated motor neuron toxicity.
- Dipeptidyl peptidase-4 (DPP4) release serves as a marker for this MMP9-dependent microglial dysregulation.
