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Updated: Sep 22, 2025
Three-dimensional Confocal Analysis of Microglia/macrophage Markers of Polarization in Experimental Brain Injury
Published on: September 4, 2013
JAK2/STAT3 Axis Intermediates Microglia/Macrophage Polarization During Cerebral Ischemia/Reperfusion Injury
Yi Zhong1, Lijuan Gu2, Yingze Ye1
1Department of Neurosurgery, Renmin Hospital of Wuhan University, China.
Background:
Subtypes of microglia/macrophage regulate the inflammation in the opposite direction during ischemic stroke. JAK2/STAT3 signaling pathway participates in the development of stroke-related inflammation via ischemic stimulation. However, the relationship between JAK2/STAT3 pathway and microglia/macrophage phenotype transformation is unclear.
Methods:
This study established a transient middle cerebral artery occlusion (tMCAO) model in male STAT3f/f and STAT3f/f LysMcre+ mice and evaluated the neurological deficit on the 3rd day using Longa score. The brains were stained by TTC to determine the infarction volume. Western blotting and QPCR were used to determine the expression of JAK2/STAT3 pathway and microglia/macrophage-related markers. Immunofluorescence staining was used to detect the levels of polarization-related indexes. QPCR also assessed the effect of STAT3 knockout on inflammatory factors in the infarction. Moreover, established the OGD/R model using BV2 cells to further verify the role of STAT3 on microglia/macrophage polarization.
Results:
For the conditioned STAT3-KO mice, the infarction was significantly increased after MCAO, accompanied by the aggravation of neurological deficit. Higher expression of iNOS and CD16/32 than Arg-1, Ym-1, and CD206 in vivo and in vitro, and decreased p-STAT3/STAT3 ratio in STAT3f/f LysMcre+ mice, while the p-JAK2/JAK2 ratio increased. In addition, increased M1/M2 ratio and elevated expression of IL-1β, IL-6, TNF-α with STAT3 deletion, as well as increased CD68+/iNOS+ cell numbers.
Conclusion:
Collectively, these results reveal that JAK2/STAT3 signaling pathway regulates the microglia/macrophage polarization (skewing toward the M2 polarization) during the CIRI, thus alleviating brain damage. Therefore, approaches targeting JAK2/STAT3 activation are promising therapies for ischemic stroke.
Insights
The JAK2/STAT3 pathway promotes M2 microglia/macrophage polarization, reducing brain damage in ischemic stroke. Targeting this pathway offers a promising therapeutic strategy for stroke recovery.
Area of Science:
- Neuroscience
- Immunology
- Molecular Biology
Background:
- Microglia/macrophage subtypes differentially regulate inflammation in ischemic stroke.
- The JAK2/STAT3 signaling pathway is implicated in stroke-related inflammation.
- The precise role of JAK2/STAT3 in microglia/macrophage phenotype modulation remains unclear.
Purpose of the Study:
- To investigate the role of the JAK2/STAT3 signaling pathway in microglia/macrophage polarization during ischemic stroke.
- To determine the therapeutic potential of targeting JAK2/STAT3 for ischemic stroke.
Main Methods:
- Established a transient middle cerebral artery occlusion (tMCAO) model in mice with STAT3 knockout in microglia/macrophages.
- Assessed neurological deficits, infarct volume, and protein/gene expression of inflammatory and polarization markers.
- Utilized an oxygen-glucose deprivation/reoxygenation (OGD/R) model in BV2 cells to confirm findings.
Main Results:
- STAT3 knockout exacerbated neurological deficits and infarct volume post-MCAO.
- STAT3 deletion led to increased M1 (pro-inflammatory) markers (iNOS, CD16/32) and decreased M2 (anti-inflammatory) markers (Arg-1, Ym-1, CD206).
- STAT3 deletion increased pro-inflammatory cytokines (IL-1β, IL-6, TNF-α) and reduced the p-STAT3/STAT3 ratio, while increasing the p-JAK2/JAK2 ratio.
Conclusions:
- The JAK2/STAT3 signaling pathway promotes M2 microglia/macrophage polarization, which is protective against ischemic brain damage.
- Targeting JAK2/STAT3 activation represents a potential therapeutic strategy for ischemic stroke.
