Downregulation of miR-15b-5p Attenuates Brain Injury After Ischemic Stroke via Targeting HSPA8

Ischemic stroke (IS) is a prevalent cerebrovascular disease characterized by rapid onset and poor treatment outcomes. miR-15b-5p was discovered to be dysregulated in IS. Yet, the relation between miR-15b-5p and IS is unknown. To investigate the role of miR-15b-5p on IS and the associated molecular mechanisms. RT-qPCR was employed to measure the levels of miR-15b-5p and HSPA8. The modified neurological severity scores (mNSS) and rotarod test were performed to evaluate the neurological damage. Dual-luciferase reporter assay was designed to validate the targeting relationship. ELISA was conducted to check the levels of inflammatory factors and oxidative stress markers. The miR-15b-5p level was elevated in 1–7 days postoperative middle cerebral artery occlusion (MCAO) rats. Furthermore, the MCAO rats were more severely neurologically impaired by mNSS scores and rotarod test. After 48 h post-surgery, the levels of TNF-α and IL-6 were elevated while IL-10 was reduced in the MCAO group. The levels of GSH-Px and SOD were declined while MDA was elevated in the MCAO group. Subsequently, a target site of miR-15b-5p, HSPA8, was identified. HSPA8 was down-regulated in 1–7 days postoperative MCAO rats. Moreover, down-regulated miR-15b-5p attenuated the neurological damage in MCAO rats, which was reversed by suppressing HSPA8. Inhibition of miR-15b-5p mitigated the inflammatory response and oxidative stress in MCAO rats, which down-regulation of HSPA8 partially reversed. Down-regulated miR-15b-5p attenuates the neurological damage, inflammation and oxidative stress in IS rats by negatively modulating HSPA8.