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Updated: Mar 19, 2026
Three-dimensional Confocal Analysis of Microglia/macrophage Markers of Polarization in Experimental Brain Injury
Published on: September 4, 2013
Neuronal Soluble Fas Ligand Drives M1-Microglia Polarization after Cerebral Ischemia
Hai-Lan Meng1, Xiao-Xi Li1, Yan-Ting Chen1,2,3,4,5
1Department of Neurology, Drum Tower Hospital, Medical School of Nanjing University, Nanjing, Jiangsu, China.
Aims:
This study explored sFasL expression in neurons and the potential role of neuronal sFasL in modulating the microglial phenotypes.
Methods:
In vivo, middle cerebral artery occlusion (MCAO) was induced in both FasL-mutant (gld) and wild-type (wt) mice. In vitro, primary cortical neuron or microglia or coculture from wt/gld mice was subjected to oxygen glucose deprivation (OGD). sFasL level in the supernatant was evaluated by ELISA. Neuronal-conditioned medium (NCM) or exogenous sFasL was applied to primary microglia with or without FasL neutralizing antibody. Protein expression of JAK2/STAT3 and NF-κB pathways were determined by Western blot. The effect of microglia phenotype from wt/gld mice on the fate of ischemic neurons was further elucidated.
Results:
In vivo, compared with wild-type mice, M1 markers (CD16, CD32 and iNOS) were attenuated in gld mice after MCAO. In vitro, post-OGD neuron released more sFasL. Both post-OGD NCM and exogenous sFasL could trigger M1-microglial polarization. However, this M1 phenotype shift was partially blocked by utilization of FasL neutralizing antibody or gld NCM. Consistently, JAK2/STAT3 and NF-κB signal pathways were both activated in microglia after exogenous sFasL treatment. Compared with wild-type mice, M1-conditioned medium prepared from gld mice protected neuron against OGD injury.
Conclusions:
Ischemic neurons release sFasL, which contributes to M1-microglial polarization. The underlying mechanisms may involve the activation of JAK2/STAT3 and NF-κB signaling pathways.
Insights
Ischemic neurons release soluble Fas Ligand (sFasL), promoting M1 microglial polarization via JAK2/STAT3 and NF-κB pathways. This neuronal sFasL contributes to stroke injury.
Area of Science:
- Neuroscience
- Immunology
- Cell Biology
Background:
- Microglial polarization is crucial in neuroinflammation and stroke pathogenesis.
- Soluble Fas Ligand (sFasL) is implicated in immune responses, but its role in neuronal-microglial interactions during ischemia is unclear.
Purpose of the Study:
- To investigate the expression of sFasL by neurons.
- To determine the role of neuronal sFasL in modulating microglial phenotypes.
- To elucidate the underlying molecular mechanisms and impact on ischemic neuronal injury.
Main Methods:
- Middle cerebral artery occlusion (MCAO) in wild-type and FasL-mutant mice.
- Oxygen-glucose deprivation (OGD) in primary neuronal and microglial cultures.
- ELISA for sFasL quantification.
- Western blot for JAK2/STAT3 and NF-κB pathway analysis.
- Treatment with conditioned medium and neutralizing antibodies.
Main Results:
- Ischemic neurons released increased sFasL.
- Exogenous sFasL and post-OGD neuronal-conditioned medium induced M1 microglial polarization.
- JAK2/STAT3 and NF-κB pathways were activated by sFasL in microglia.
- Reduced M1 markers and neuroprotection were observed with FasL deficiency.
Conclusions:
- Ischemic neurons release sFasL, driving M1 microglial polarization.
- JAK2/STAT3 and NF-κB signaling pathways mediate sFasL's effects on microglia.
- Neuronal sFasL contributes to ischemic brain injury by promoting detrimental microglial phenotypes.
