Effect and mechanism of microRNA-126-3p on inflammatory response after spinal cord injury in rats

Abstract

Objective To investigate the effect and mechanism of microRNA (miRNA, miR)-126-3p on inflammatory response after spinal cord injury in rats. Methods The SD rat model of spinal cord injury was established. The relative expression of miR-126 in the spinal cord tissues of 3, 7 and 14 d after spinal cord injury in rats was detected by real-time fluorescent quantitative polymerase chain reaction (FQ-PCR). The effect of agomir-126 injection on the motor function of rats with acute spinal cord injury was evaluated by Basso-Beattie-Bresnahan (BBB) scoring method, and the online target gene was used to predict the database Targetscan. The target gene of miR-126-3p was predicted and the target gene of agomir-126 was verified by double luciferase reporter gene. After transfecting NEURO-2A cells to 150 nmol/L concentration miR-126-3p mimics for 24 hours, Western blotting was used to detect the change of the expression level of interleukin (IL)-7 protein, and Western blotting was used to detect the agomir-126 administration group. In the negative control group (agomir-NC), the expression level of inflammation related factors in spinal cord injured rats was changed. Results The expression level of miR-126 in spinal cord tissue of model group (2.13±0.44) in 3 days was lower than that of control group (3.69±0.59, t=2.769, P=0.021). The expression level of miR-126 in spinal cord tissue of model group (1.85±0.42) in 7 days was lower than that of control group (3.77±0.88, t=2.485, P=0.026). The expression level of miR-126 in spinal cord tissue of model group (1.33±0.28) in 14 days was lower than that of control group (3.82±0.92, t=3.388, P=0.019). The BBB score of 3 days in the agomir-126 group (4.690±0.530) was higher than that of the control group (3.650±0.350, t=3.661, P=0.006); The BBB score of 7 days in the agomir-126 group was higher than that of the control group (3.690±0.650, t=5.452, P=0.001), and agomir-126 administration group 14 days (6.720±0.770) was higher than that of the control group (3.770±0.470, t=7.320, P=0.001). The luciferase activity ratio of IL-7-WT-3’UTR and miR-126-3p mimic co-transfection group (6.92±0.556) was significantly lower than that of the control group (13.69±0.925, t=10.870, P=0.001). The expression of IL-7 protein in miR-126 mimic transfection group (0.23±0.14) NEURO-2A cells was lower than that in the control group (0.86±0.17, t=4.955, P=0.009). The expression of IL-7 protein in the spinal cord of the drug group (0.369±0.093) SCI rats was lower than that of the control group (0.956±0.124, t=6.559, P=0.003), and the expression of IL-1 beta protein in the spinal cord of the administration group (0.572±0.085) SCI rats was lower than that of the control group (0.764±0.086, t=2.750, P=0.026), and the spinal cord of the drug group (0.133±0.009) SCI rat ridges The expression of TGF- beta protein was lower than that in the control group (0.257±0.028, t=7.303, P=0.002). Conclusion The expression of miR-126-3p in spinal cord injury is reduced, and up regulation of miR-126-3p can protect the spinal cord injury. The mechanism may be related to the inflammatory response of the spinal cord injury mediated by the key target gene IL-7. Key words: Spinal cord injury; MicroRNA-126; Interleukin-7; Inflammatory response