MiR‑126 overexpression attenuates oxygen‑glucose deprivation/reperfusion injury by inhibiting oxidative stress and inflammatory response via the activation of SIRT1/Nrf2 signaling pathway in human umbilical vein endothelial cells.

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MicroRNA-126 (miR-126) has been reported to be implicated in the pathogenesis of cerebral ischemia/reperfusion (I/R) injury; however, its role is still unclear and requires further investigation. The objective of the present study was to determine the neuroprotective effect of miR-126 overexpression against oxygen-glucose deprivation/reoxygenation (OGD/R)-induced human umbilical vein endothelial cell (HUVEC) injury, an in vitro model of cerebral I/R injury, and to further explore the role of the NAD-dependent protein deacetylase sirtuin-1 (SIRT1)/nuclear factor erythroid 2-related factor 2 (Nrf2) signaling pathway in this process. The results of the present study revealed that miR-126 expression was markedly reduced in HUVECs subjected to OGD/R treatment. Functional experiments demonstrated that transfection with miR-126 mimics attenuated OGD/R-induced down-regulation of cell viability, and reversed OGD/R-induced up-regulation of lactate dehydrogenase release, apoptosis and caspase-3 activity in HUVECs. Notably, OGD/R reduced SIRT1 and heme oxygenase-1 expression, and induced the nuclear translocation of Nrf2, as demonstrated by the increase in cytoplasmic Nrf2 expression and the decrease in nuclear Nrf2 expression. Following transfection with miR-126 mimics, these effects of OGD/R were reversed, indicating that miR-126 overexpression promoted the SIRT1/Nrf2 signaling pathway. Additionally, miR-126 mimics attenuated OGD/R-induced cytotoxicity and apoptosis, which was blocked by inhibition of the SIRT1/Nrf2 signaling pathway followed by transfection with SIRT1-small interfering RNA (siRNA). Furthermore, miR-126 mimics decreased ROS generation and malondialdehyde content, and increased superoxide dismutase and glutathione peroxidase activity in HUVECs exposed to OGD/R, and these effects of miR-126 mimics were also blocked by SIRT1-siRNA. Additionally, the miR-126 mimics-induced the decreases in the levels of pro-inflammatory cytokines, including tumor necrosis factor-α, interleukin (IL)-1β and IL-6, and the miR-126 mimics-induced increase in anti-inflammatory cytokines, including IL-10, were reversed by SIRT1-siRNA. Overall, these results suggested that miR-126 overexpression attenuated OGD/R-induced neurotoxicity to HUVECs by alleviating oxidative stress and the inflammatory response via promotion of the SIRT1/Nrf2 signaling pathway.