Suppression of microRNA-320 Induces Cerebral Protection Against Ischemia/Reperfusion Injury by Targeting HMGB1/NF-κB Axis

Abstract

MicroRNAs have been shown to potentially function in cerebral ischemia/reperfusion (IR) injury. This study aimed to examine the expression of microRNA-320 (miR-320) in cerebral IR injury and its involvement in cerebral mitochondrial function, oxidative stress, and inflammatory responses by targeting the HMGB1/ NF-κB axis. Sprague-Dawley rats were subjected to middle cerebral artery occlusion to simulate cerebral IR injury. The cerebral expression of miR-320 was assessed using qRT-PCR. Neurological function, cerebral infarct volume, mitochondrial function, oxidative stress, and inflammatory cytokines were evaluated using relevant methods, including staining, fluorometry, and ELISA. HMGB1 expression was analyzed through Western blotting. The levels of miR-320, HMGB1, neurological deficits, and cerebral infarction were significantly higher after IR induction. Intracerebral overexpression of miR-320 resulted in substantial neurological deficits, increased infarct volume, elevated levels of 8-isoprostane, NF-κBp65, TNF-α, IL-1β, ICAM-1, VCAM-1, and HMGB1 expression. It also promoted the loss of mitochondrial membrane potential and ROS levels while reducing MnSOD and GSH levels. Downregulation of miR-320 and inhibition of HMGB1 activity significantly reversed the outcomes of cerebral IR injury. MiR-320 plays a negative role in regulating cerebral inflammatory/oxidative reactions induced by IR injury by enhancing HMGB1 activity and modulating mitochondrial function.