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Updated: Jun 10, 2025
Three-dimensional Confocal Analysis of Microglia/macrophage Markers of Polarization in Experimental Brain Injury
Published on: September 4, 2013
DHA plays a protective role in cerebral ischemia-reperfusion injury by affecting macrophage/microglia type
Yimin Jin1, Tiantian Pu2, Tongshuai Zhang2
1Department of Neurology, The First Affiliated Hospital of Harbin Medical University, Harbin, No. 23 Youzheng Street, Nangang District, Heilongjiang 150001, PR China.
Abstract:
A close correlation exists between the macrophage/microglia(MΦ/MG) polarization states and the development of cerebral ischemia and reperfusion (I/R). Therefore it is of great significance to research on how to modulate the MΦ/MG states for improved patient outcomes. In particular, regulatory mechanisms involved in this process remain to be identified. Hereby, we aim to shed light on how docosahexaenoic acid (DHA) actively modulates the switch between M1 and M2 macrophage states by restraining the NACHT-LRR-PYD-containing protein three inflammasome (NALP3). We found that NALP3-positive cells were detected in clinical human cerebral infarction tissue samples and the mouse tMCAO model. In mice after DHA treatment, the number of NALP3-positive cells was significantly reduced, significantly decreasing infarct volume and improving the postoperative physical status of mice. NALP3-positive cells were found to be MΦ/MG after co-staining with CD11b. By extracting peritoneal macrophages, it was verified that DHA inhibited the activation of NALP3 and regulated the transformation of M1 and M2 cells, thereby reducing I/R injury.
Insights
Docosahexaenoic acid (DHA) reduces brain injury after stroke by inhibiting the NALP3 inflammasome, shifting macrophage/microglia (MΦ/MG) from inflammatory M1 to protective M2 states.
Area of Science:
- Neuroscience
- Immunology
- Biochemistry
Background:
- Macrophage/microglia (MΦ/MG) polarization is closely linked to cerebral ischemia and reperfusion (I/R) injury.
- Understanding MΦ/MG modulation is crucial for improving patient outcomes after stroke.
- Regulatory mechanisms governing MΦ/MG polarization in I/R injury require further elucidation.
Purpose of the Study:
- To investigate how docosahexaenoic acid (DHA) modulates MΦ/MG polarization states.
- To explore the role of the NACHT-LRR-PYD-containing protein three inflammasome (NALP3) in DHA-mediated effects.
- To determine if DHA can mitigate I/R injury by targeting the NALP3 inflammasome.
Main Methods:
- Detection of NALP3-positive cells in human cerebral infarction tissues and a mouse tMCAO model.
- Administration of DHA to mice and assessment of NALP3-positive cell counts, infarct volume, and physical status.
- Co-staining of NALP3-positive cells with CD11b to identify them as MΦ/MG.
- In vitro experiments using peritoneal macrophages to verify DHA's effect on NALP3 activation and M1/M2 polarization.
Main Results:
- NALP3-positive cells were found in human stroke tissues and the mouse model.
- DHA treatment significantly reduced NALP3-positive cells, infarct volume, and improved physical function in mice.
- NALP3-positive cells were confirmed to be MΦ/MG.
- DHA inhibited NALP3 activation and modulated M1/M2 macrophage polarization in vitro.
Conclusions:
- Docosahexaenoic acid (DHA) plays a protective role in cerebral I/R injury.
- DHA mitigates I/R injury by restraining the NALP3 inflammasome.
- DHA promotes a shift from M1 to M2 macrophage polarization, reducing inflammation and tissue damage.
