MiR-325-3p promotes locomotor function recovery in rats with spinal cord injury via inhibiting the expression of neutrophil elastase

OBJECTIVE: This study aims to investigate the potential function of miR-325-3p in vascular integrity and inflammatory response following spinal cord injury (SCI). MATERIALS AND METHODS: The protein levels of ANG-1, ANG-2, and caspase-3 in HUVECs incubated with 0, 100, 200, 400. and 800 ng/ml NE for 24 h were determined. The regulatory effect of overexpressed miR-325-3p on the protein levels of ANG-1 and ANG-2 was determined by Western blot. The SCI model in SD rats was established by spinal injury at T10. Subsequently, the relative levels of miR-325-3p. ANG-1. and ANG-2 were determined in SCI rats and controls. Furthermore, SCI rats were administrated with miR-325-3p mimics or negative control and the relative levels of miR-325-3p, ANG-1. and ANG2 were examined as well. At day 14, the protein levels of iNOS and GFAP in SCI rats and those overexpressing miR-325-3p were detected. BBB (Basso, Beattie, and Bresnahan) locomotor rating scale was applied for evaluating the locomotor function recovery at day 1, 3, 7, 14, 21, and 28 following SCI. RESULTS: NE treatment in HUVECs downregulated ANG-1 and upregulated ANG-2 and caspase-3 in a dose-dependent manner. The overexpression of miR-325-3p upregulated NE-induced decreased the level of ANG-1 and downregulated NE-induced increased level of ANG-2. After the establishment of the SCI model in rats, the miR-325-3p level gradually decreased in SCI rats relative to controls in a time-dependent manner. ANG-1 level in SCI rats decreased to the lowest on the first day following SCI. and gradually increased at day 3. 5. and 7. ANG-2 level was firstly upregulated and achieved the peak on day 3, and then decreased at at day 5 and 7. Moreover. SCI rats overexpressing miR-325-3p showed a higher level of ANG-1 and lower level of ANG-2 than those of SCI rats. Overexpression of miR-325-3p downregulated the protein levels of iNOS and GFAP in SCI rats. BBB scale showed elevated locomotor function recovery in SCI rats overexpressing miR-325-3p compared with SCI rats. CONCLUSIONS: MiR-325-3p protects the integrity of the vascular wall, reduces infiltration of inflammation, and improves locomotor function recovery at post-SCI.