Related Experiment Video
Updated: May 21, 2026
Characterization and Isolation of Mouse Primary Microglia by Density Gradient Centrifugation
Published on: February 16, 2018
Transformation from a neuroprotective to a neurotoxic microglial phenotype in a mouse model of ALS
Bing Liao1, Weihua Zhao, David R Beers
1Department of Neurology, Xiangya Hospital, Central South University, Changsha, 410008, China. biliao@utmb.edu
Abstract:
Neuroinflammation is a prominent pathological feature in the spinal cords of patients with amyotrophic lateral sclerosis (ALS), as well as in transgenic mouse models of inherited ALS, and is characterized by activated microglia. Earlier studies showed that activated microglia play important roles in both motoneuron protection and injury. More recent studies investigating the pathoprogression of disease in ALS mice have demonstrated that the in vivo activation states of microglia, including their anti- versus pro-inflammatory responses, are best characterized as a continuum between two extreme activation states which are represented as a neuroprotective M2 (alternatively-activated) phenotypic state or an injurious/toxic M1 (classically-activated) state; a more complete understanding and determination the temporal transformation of microglia activation states in the ALS disease pathoprogression is therefore warranted. In the current study, we demonstrated a phenotypic and functional transformation of adult ALS mice microglia that overexpress mutant superoxide dismutase (mSOD1). mSOD1 microglia isolated from ALS mice at disease onset expressed higher levels of Ym1, CD163 and BDNF (markers of M2) mRNA and lower levels of Nox2 (a marker of M1) mRNA compared with mSOD1 microglia isolated from ALS mice at end-stage disease. More importantly, when co-cultured with motoneurons, these mSOD1 M2 microglia were neuroprotective and enhanced motoneuron survival than similarly co-cultured mSOD1 M1 microglia; end-stage mSOD1 M1 microglia were toxic to motoneurons. Our study documents that adult microglia isolated from ALS mice at disease onset have an M2 phenotype and protect motoneurons whereas microglia isolated from end-stage disease ALS mice have adopted an M1 phenotype and are neurotoxic supporting the dual phenotypes of microglia and their transformation during disease pathoprogression in these mice. Thus, harnessing the neuroprotective potential of microglia may provide novel avenues for ALS therapies.
Insights
Microglia in amyotrophic lateral sclerosis (ALS) mice shift from a protective M2 state at disease onset to a toxic M1 state at end-stage. This transformation impacts motoneuron survival, offering potential therapeutic targets for ALS.
Area of Science:
- Neuroscience
- Immunology
- Neurodegenerative Diseases
Background:
- Neuroinflammation, characterized by activated microglia, is central to amyotrophic lateral sclerosis (ALS) pathology.
- Microglia exhibit a spectrum of activation states, broadly classified as M1 (pro-inflammatory, injurious) and M2 (anti-inflammatory, protective).
- The temporal dynamics of microglial activation states during ALS progression remain incompletely understood.
Purpose of the Study:
- To investigate the phenotypic and functional transformation of microglia in a mouse model of inherited ALS (mSOD1).
- To determine the temporal changes in microglial activation states from disease onset to end-stage.
- To assess the impact of different microglial activation states on motoneuron survival.
Main Methods:
- Isolation and characterization of microglia from mSOD1-mutant ALS mice at disease onset and end-stage.
- Quantitative analysis of M1 and M2 marker gene expression (Ym1, CD163, BDNF, Nox2).
- Co-culture experiments with isolated microglia and motoneurons to evaluate neuroprotection/toxicity.
Main Results:
- Microglia from early-stage ALS mice (disease onset) exhibited an M2 phenotype, expressing higher levels of M2 markers and lower M1 markers.
- Microglia from end-stage ALS mice displayed an M1 phenotype, with increased M1 markers and decreased M2 markers.
- Early-stage M2 microglia were neuroprotective to motoneurons, while end-stage M1 microglia were neurotoxic.
Conclusions:
- Microglia undergo a phenotypic and functional transformation during ALS progression in mSOD1 mice, shifting from a neuroprotective M2 state to a neurotoxic M1 state.
- This temporal shift in microglial activation correlates with motoneuron survival, highlighting their dual role in ALS.
- Targeting the neuroprotective functions of microglia presents a potential therapeutic strategy for ALS.
