MicroRNA-381 Favors Repair of Nerve Injury Through Regulation of the SDF-1/CXCR4 Signaling Pathway via LRRC4 in Acute Cerebral Ischemia after Cerebral Lymphatic Blockage

Abstract

Acute cerebral ischemia is a manifestation of cerebral vascular insufficiency and has a high mortality. However, the therapy for acute cerebral ischemia is still limited. This study aimed to investigate the effect of microRNA-381 (miR-381) on the repair of nerve injury in rats with acute cerebral ischemia after cerebral lymphatic blockage (CLB) by targeting leucine-rich repeat C4 protein (LRRC4) through the Stromal cell-derived factor-1/CXC chemokine receptor-4 signaling pathway. Rat models of CLB and middle cerebral artery occlusion (MCAO) were established, and 56 Wistar rats were divided into sham, MCAO, CLB + MCAO, CLB + MCAO + miR-381 inhibitor, CLB + MCAO + miR-381 mimic, CLB + MCAO + AMD3100 and CLB + MCAO + miR-381 mimic + AMD3100 groups. Modified neurological severity score (mNSS was used to determine nerve injury, TTC staining to measure infarction volume, terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) staining and flow cytometry to evaluate cell apoptosis, immunofluorescence to measure BrdU-positive cell number, enzyme-linked immunosorbent assay (ELISA) to determine contents of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), interleukin-6 (IL-6), interleukin-10 (IL-10), nerve growth factor (NGF) and neurite outgrowth inhibitor -A (Nogo-A), Reverse transcription quantitative polymerase chain reaction (RT-qPCR) and Western blotting to evaluate expression of miR-381, LRRC4, SDF-1, CXCR4, pERK, Slit2 and vascular endothelial growth factor (VEGF). LRRC4 was a target gene of miR-381. Compared with the results in the CLB + MCAO group, mNSS, infarction volume, apoptosis rate and TNF-α, IL-1β, IL-6 and Nogo-A contents as well as LRRC4 expression in the CLB + MCAO + miR-381 inhibitor and CLB + MCAO + AMD3100 groups were increased (those in the CLB + MCAO + AMD3100 group > those in the CLB + MCAO + miR-381 mimic + AMD3100 group), while BrdU-positive cell number, contents of NGF and IL-10, and expression of SDF-1, CXCR4, pERK, Slit2 and VEGF in brain tissues were decreased (those in the CLB + MCAO + AMD3100 group < those in the CLB + MCAO + miR-381 mimic + AMD3100 group). The results in the CLB + MCAO + mimic group were opposite of those in the CLB + MCAO + miR-381 inhibitor and CLB + MCAO + AMD3100 groups. Taken together, we concluded that up-regulation of miR-381 promoted nerve injury repair in acute cerebral ischemia rats after CLB by negatively regulating LRRC4 through activating the SDF-1/CXCR4 signaling pathway.