MiR-223-3p promote microglia "M2" polarization by targeting FOXO3a in subarachnoid hemorrhage.

OBJECTIVE

Exosome-derived micorRNAs (miRs) play important role in regulation the inflammatory response in subarachnoid hemorrhage (SAH). However, the ability of miR-223-3p, which is enriched in astrocyte-derived exosomes, to regulate FOXO3a in microglia is still unclear.

METHODS

MiR-223-3p in CSF from SAH patients was measured by qRT-PCR. Rats and BV2 cells were used to establish SAH model. Neurological function was evaluated by the mNSS, rotarod test, and Morris water maze. QRT-PCR and enzyme-linked immunosorbent assay (ELISA) were used to analyze oxidative stress and inflammatory factors interleukin-1β (IL-1β), IL-6 and tumor necrosis factor α (TNF-α). The levels of FOXO3a, TLR4, NLRP3, NF-κB, iNOS, Cox2, Nrf2 and HO-1 were detected by WB. The exosomes were labeled with KPH67, and uptaken by microglia, detecting by IF.

RESULTS

Among the miRs involved in SAH, miR-223-3p exhibited one of the greatest change. MiR-223-3p in the brain tissue of SAH rats was upregulated. Moreover, the upregulation of miR-223-3p significantly improved neurological deficits and reduced brain edema. Meanwhile, miR-223-3p reduced the inflammatory factors like IL-1β, IL-6, TNF-α, and decreased oxidative stress, inhibited the activation of NF-κB, TLR4/NLRP3 in microglia by targeting Foxo3a. The "M1" polarization marker, including iNOS, Cox2, TLR4, NLRP3 and NF-κB, in microglia decreased markedly after the overexpression of miR-223-3p. Moreover, miR-223-3p targets FOXO3a and inhibits it expression no matter in vitro or in vivo. In vitro, both miR-223-3p mimics and astrocyte-derived exosomes obviously increased the expression of miR-223-3p in microglia.

CONCLUSION

In SAH, astrocyte-derived exosomes rich in miR-223-3p may regulate the activation and phenotype of microglia by targeting FOXO3a, resulting in the inhibition of inflammatory injury.