Down-regulation of circular RNA CDC14A peripherally ameliorates brain injury in acute phase of ischemic stroke

BACKGROUND: Inflammation is integral to the pathophysiology of ischemic stroke and a prime target for the development of new stroke therapies. The aim of the present study is to seek out the regulatory mechanism of circCDC14A in neuroinflammatory injury in tMCAO mice. METHODS: The expression level of circCDC14A in peri-infarct cortex and plasma of mice were detected by qPCR. The localization of circCDC14A in peripheral blood cells and peri-infarct cortex of tMCAO mice were explored by in situ hybridization and immunofluorescence colocalization staining. Lentivirus were microinjected into lateral ventricular of brain or injected into tail vein to interfere with the expression of circCDC14A, thus their effects on behavior, morphology, and molecular biology of tMCAO mice were analyzed. RESULTS: The expression of circCDC14A in plasma and peri-infarct cortex of tMCAO mice significantly increased, and circCDC14A was mainly localized in neutrophils peripherally while in astrocytes in peri-infarct cortex centrally. Tail vein injection of lentivirus to interfere with the expression of circCDC14A significantly reduced the infarct volume (P < 0.01) at 72 h after reperfusion and density of activated astrocytes in peri-infarct cortex at 3 days, 5 days and 7 days after tMCAO modeling (all P < 0.0001). Moreover, mNSS (P < 0.0001) and survival rate (P < 0.001) were significantly improved within 7 days in si-circCDC14A group compared to circCon group. Additionally, morphology analysis showed the volume and surface area of each activated astrocytes significantly decreased (P < 0.0001). Quantification analysis measured the percentage of N2 phenotype among infiltrated neutrophils in brain sections and found N2 ratio was significantly higher in si-circCDC14A group compared to circCon group (P < 0.001). CONCLUSION: Knocking down the expression of circCDC14A in peripheral blood cells relieved astrocytes activation in peri-infarct cortex, thereby relieved brain damage in the acute phase of ischemic stroke. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12974-021-02333-6.