The Mechanism Study of Regulation of Neuroinflammation After Subarachnoid Hemorrhage by Esculin via GSK-3β/C/EPB-β

Introduction: Subarachnoid hemorrhage (SAH) is a severe subtype of stroke, with ruptured aneurysm as the primary cause, high prehospital mortality, and poor prognosis. After SAH, the infiltration of peripheral blood leukocytes appears earlier, and the infiltrated neutrophils will stimulate the residing microglia and activate the innate immune response, which is the key to the inflammatory response of the brain after SAH. GSK-3β is a serine/threonine protein kinase. It mediates microglial polarization through the C/EBP-β signaling pathway, but the role of this pathway in acute brain injury with SAH is unknown. Esculin regulates C/EBP-β phosphorylation by decreasing GSK-3β phosphorylation. This study focused on whether esculin regulates post-SAH neuroinflammation by regulating microglial polarization through the GSK-3β /C/ EBP-β pathway.

Methods: In vitro experiment，the expression levels of M1 and M2 biomarkers in BV2 cells were detected by WB. The polarization of microglia M1/M2 was detected by flow cytometry, Q-PCR was used to detect the mRNA expression of inflammatory factors and target proteins. The expression of microglia was detected by immunofluorescence staining and TUNEL.
In vivo experiment，SAH model was constructed by carotid artery puncture in mice, and do the same experimentas as above to detect the corresponding indicators.

Results: After SAH, the expression of GSK-3β showed an upward trend, while the expression of p-GSK-3β decreased. After the administration of esculin, the expression of p-GSK-3β increased, and meanwhile, the phosphorylation level of C/EBP-β was regulated. By regulating the GSK-3β/C/ EBP-β pathway, esculin could adjust the polarization state of microglia. The neuroinflammatory injury after SAH can be effectively alleviated.

Conclusion : These results suggest that esculin can regulate microglial polarization through GSK-3β/C/EPBβ pathway, reduce neuroinflammation after SAH, and provide a possible drug target for the treatment of SAH.