Related Experiment Video
Updated: Apr 21, 2026
Isolation of Cortical Microglia with Preserved Immunophenotype and Functionality From Murine Neonates
Published on: January 30, 2014
Abnormal microglial activation in the Cstb(-/-) mouse, a model for progressive myoclonus epilepsy, EPM1
Olesya Okuneva1, Inken Körber, Zhilin Li
1Folkhälsan Institute of Genetics, Haartmaninkatu 8, 00014, Helsinki, Finland; Haartman Institute, Department of Medical Genetics and Research Program's Unit, Molecular Neurology, University of Helsinki, Haartmaninkatu 8, 00014, Helsinki, Finland; Neuroscience Center, University of Helsinki, Viikinkaari 4, 00014, Helsinki, Finland.
Abstract:
Progressive myoclonus epilepsy of Unverricht-Lundborg type (EPM1) is an autosomal-recessively inherited neurodegenerative disorder characterized by severely incapacitating myoclonus, seizures, and ataxia, and caused by loss-of-function mutations in the cystatin B gene (CSTB). A central neuropathological finding in the Cstb(-/-) mouse, an animal model for EPM1, is early microglial activation, which precedes astroglial activation, neuronal loss, and onset of myoclonus, thus implying a critical role for microglia in EPM1 pathogenesis. Here, we characterized phenotypic and functional properties of microglia from Cstb(-/-) mice utilizing brain tissue, microglia directly isolated from the brain, and primary microglial cultures. Our results show significantly higher Cstb mRNA expression in microglia than in neurons and astrocytes. In Cstb(-/-) mouse brain, expression of the inflammatory marker p-p38 MAPK and the proportion of both pro-inflammatory M1 and anti-inflammatory M2 microglia is higher than in control mice. Moreover, M1/M2 polarization of microglia in presymptomatic Cstb(-/-) mice is, compared to control mice, skewed towards M2 type at postnatal day 14 (P14), but towards M1 type at P30, a time point associated with onset of myoclonus. At this age, the high expression of both pro-inflammatory inducible nitric oxide synthase (iNOS) and anti-inflammatory arginase 1 (ARG1) in Cstb(-/-) mouse cortex is accompanied by the presence of peripheral immune cells. Consistently, activated Cstb(-/-) microglia show elevated chemokine release and chemotaxis. However, their MHCII surface expression is suppressed. Taken together, our results link CSTB deficiency to neuroinflammation with early activation and dysfunction of microglia and will open new avenues for therapeutic interventions for EPM1.
Insights
Progressive myoclonus epilepsy (EPM1) is linked to cystatin B gene mutations. This study reveals early microglial activation and dysfunction in EPM1 mouse models, suggesting new therapeutic targets for neuroinflammation.
Area of Science:
- Neuroscience
- Immunology
- Genetics
Background:
- Progressive myoclonus epilepsy of Unverricht-Lundborg type (EPM1) is a severe neurodegenerative disorder caused by mutations in the cystatin B gene (CSTB).
- Early microglial activation is a key neuropathological finding in EPM1 mouse models, preceding neuronal loss and disease symptoms.
Purpose of the Study:
- To characterize the phenotypic and functional properties of microglia in a mouse model of EPM1.
- To investigate the role of microglia in the pathogenesis of EPM1.
Main Methods:
- Analysis of microglial properties using brain tissue, isolated microglia, and primary microglial cultures from Cstb(-/-) mice.
- Assessment of gene expression (CSTB, p-p38 MAPK, iNOS, ARG1) and cell surface markers (MHCII).
- Evaluation of microglial inflammatory markers, polarization (M1/M2), chemokine release, and chemotaxis.
Main Results:
- CSTB mRNA expression is significantly higher in microglia than in neurons and astrocytes.
- Cstb(-/-) mice exhibit increased inflammatory markers (p-p38 MAPK) and altered M1/M2 microglial polarization, shifting towards M1 at disease onset.
- Activated Cstb(-/-) microglia show enhanced chemokine release and chemotaxis but suppressed MHCII expression, with evidence of peripheral immune cell infiltration.
Conclusions:
- CSTB deficiency is associated with early microglial activation, dysfunction, and neuroinflammation in EPM1.
- These findings highlight microglia as critical players in EPM1 pathogenesis.
- The study opens new avenues for therapeutic interventions targeting microglial dysfunction in EPM1.
