A2 reactive astrocyte-derived exosomes alleviate cerebral ischemia-reperfusion injury by delivering miR-628.

Ischemia and hypoxia activate astrocytes into reactive types A1 and A2, which play roles in damage and protection, respectively. However, the function and mechanism of A1 and A2 astrocyte exosomes are unknown. After astrocyte exosomes were injected into the lateral ventricle, infarct volume, damage to the blood-brain barrier (BBB), apoptosis and the expression of microglia-related proteins were measured. The dual luciferase reporter assay was used to detect the target genes of miR-628, and overexpressing A2-Exos overexpressed and knocked down miR-628 were constructed. qRT-PCR, western blotting and immunofluorescence staining were subsequently performed. A2-Exos obviously reduced the infarct volume, damage to the BBB and apoptosis and promoted M2 microglial polarization. RT-PCR showed that miR-628 was highly expressed in A2-Exos. Dual luciferase reporter assays revealed that NLRP3, S1PR3 and IRF5 are target genes of miR-628. After miR-628 was overexpressed or knocked down, the protective effects of A2-Exos increased or decreased, respectively. A2-Exos reduced pyroptosis and BBB damage and promoted M2 microglial polarization through the inhibition of NLRP3, S1PR3 and IRF5 via the delivery of miR-628. This study explored the mechanism of action of A2-Exos and provided new therapeutic targets and concepts for treating cerebral ischemia.