Abstract:

Objective This study aims to investigate the regulatory effect of miR-let-7f on oxygen-glucose deprivation-induced inflammatory responses in microglia and its underlying molecular mechanism. Methods The murine microglial cell line BV2 was cultured to establish an oxygen-glucose deprivation/reoxygenation （OGD/R） cell model. miR-let-7f mimics and inhibitors were designed and synthesized. Quantitative real-time PCR （qPCR） and enzyme-linked immunosorbent assay （ELISA） were employed to quantify the expression levels of miR-let-7f， high mobility group AT-hook 2 （HMGA2）， and inflammatory cytokines across all treatment groups. Cellular immunofluorescence staining was conducted to visualize the subcellular localization and activation status of microglia. Results Transfection with miR-let-7f mimics and inhibitor significantly upregulated and downregulated miR-let-7f expression in BV2 cells， respectively （P < 0.000 1）. OGD/R treatment increased the expression of the pro-inflammatory protein HMGA2 and the inflammatory cytokines tumor necrosis factor-alpha （TNF-α） and interleukin-1 beta （IL-1β） （P < 0.05）， accompanied by increased nuclear translocation of NF-κB p65. Treatment with miR-let-7f mimics significantly reduced HMGA2 and inflammatory cytokine levels （P < 0.05） and decreased NF-κB p65 nuclear translocation. Following the addition of the miR-let-7f inhibitor， these inhibitory effects were significantly attenuated （P < 0.05）. Conclusions miR-let-7f exerts anti-inflammatory effects in BV2 microglia under OGD/R conditions. This bioactivity may be mediated via the regulation of HMGA2 expression and subsequent suppression of the NF-κB signaling pathway. The present study provides robust experimental evidence for the intervention of neuroinflammation secondary to cerebral ischemia and hypoxia.

Key words: oxygen-glucose deprivation, miR-let-7f, inflammation, nuclear factor kappa B