MiR-543-3p promotes locomotor function recovery after spinal cord injury by inhibiting the expression of tumor necrosis factor superfamily member 15 in rats

OBJECTIVE: To explore the effect of miR-543-3p on the recovery of locomotor function after spinal cord injury (SCI) by regulating tumor necrosis factor superfamily member 15 (TNFSF15) mediated inflammation and apoptosis. MATERIALS AND METHODS: Macrophages were isolated from the abdominal cavity of 2-3 months old Sprague-Dawley (SD) rats and cultured. The levels of miR-543-3p, tumor necrosis factor superfamily member 15 (TNFSF15), TNF-like molecule 1A (TL1A) and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-.B) after transfection of miR-92b-5p into activated macrophages were detected by quantitative Real-time polymerase chain reaction (qRT-PCR). Moreover, the mRNA expressions of miR-543-3p, TNFSF15, TL1A and NF-kappa B after SCI in rats were detected by qRT-PCR. Meanwhile, the protein expressions of tumor necrosis factor (TNF-alpha), interleukin-1 beta (IL-1 beta) and Caspase8 were detected by Western blot. After intrathecal injection of miR-543-3p mimics, the mRNA expressions of miR-543-3p, TNFSF15, TL1A and NF-kappa B and the protein expressions of TNF-alpha, IL-1 beta and Caspase8 in spinal cord injured area of mice were measured by qRT-PCR and Western blot, respectively. Basso Beattie Bresnahan (BBB) locomotor rating scale was used to determine the recovery of locomotor function after spinal cord injury and injection of miR-543-3p mimics. RESULTS: Compared with inactivated cells, the expression of miR-543-3p in activated macrophages was significantly declined. However, the levels of TNFSF15, TL1A and NF-kappa B were significantly elevated. The expressions of TNFSF15, TL1A and NF-kappa B were remarkably downregulated after transfection of miR-543-3p. In addition, the level of miR-543-3p was significantly downregulated, accompanied by an increase in TNFSF15, TL1A and NF-kappa B in SCI rats. Accordingly, the protein levels of TNF-alpha and IL-1 beta and Caspase8 were also significantly increased. However, the expressions of TNFSF15, TL1A and NF-kappa B were significantly down-regulated in rats injected with miR-543-3p mimics, whereas the protein levels of TNF-alpha and IL-1 beta and Caspase8 were significantly suppressed. Finally, compared with SCI group, the recovery of locomotor function in miR-543-3p mimics administration group was significantly improved. CONCLUSIONS: After SCI, miR-543-3p can inhibit the activity of NF-kappa B by suppressing the inflammatory aggravation of TNFSF15 and decreasing its product TL1A. MiR-543-3p leads to the improvement of neuron protection and locomotor function via attenuating inflammatory reaction and cell apoptosis.