Activation of GPER1 alleviates white matter injury by promoting microglia M2 polarization through EGFR/Stat3 pathway in intracerebral hemorrhage mice

Background

White matter injury (WMI) is a major pathophysiological process after intracerebral hemorrhage (ICH). G protein-coupled estrogen receptor 1 (GPER1) has been validated to exert a crucial role in regulating neuroinflammation and microglia polarization. Our previous report reveals activation of GPER1 improves the neurological deficits after ICH via inhibition of A1 astrocytes. However, the role of GPER1 on the protection of WMI and modulation of microglia polarization after ICH remains unclear.

Methods

In present study, ICH mice model was induced by autologous whole blood injection and in vitro ICH model was established via treatment BV2 cells with FeSO₄. Mice were treated with GPER1 agonist G1, antagonist G15 and BV2 cells were treated with G1, G15 or EGFR inhibitor AG1478. Besides, BV2 conditional medium was used to intervene MO3.13 oligodendrocytes. Immunostaining, immunoblots, transmission electron microscope and PI staining were used to determine the WMI, microglia polarization and potential molecular mechanism after ICH, respectively.

Results

Our data showed treatment with G1 ameliorated the WMI on the day 3 after ICH. Besides, activation of GPER1 reduced the release of IL-1β, TNF-α and increased the produce of IL-4, IL-10 as well as shifting microglia from proinflammatory M1 to anti-inflammatory M2 phenotype in vivo and in vitro. Meanwhile, MO3.13 cells treated with BV2 conditional medium validated GPER1 alleviated oligodendrocytes death via mitigating neuroinflammation and modulating microglia polarization. Mechanistic study demonstrated EGFR/Stat3 signaling pathway was involved in the protection of WMI and modulation microglia polarization after ICH.

Conclusion

Collectively, our findings demonstrated activation of GPER1 alleviated WMI via modulating microglia M2 polarization after ICH through EGFR/Stat3 signaling pathway.