Bacillus Calmette Guerin Injection Improves Hindlimb Motor Function and Alleviates Inflammation through Upregulating Foxp3 Expression in Rats with Spinal Cord Injury

Background: Immune and inflammatory reactions are important factors leading to secondary spinal cord injury. Aim: This study aimed to investigate the effect of BCG on behavior after acute spinal cord injury in rats and its related mechanisms. Methods: Rats with spinal cord injury were generated according to modified Allen’s method. Rats were divided into the BCG group (rats with spinal cord injury intraperitoneally injecting with BCG), Model group (rats with spinal cord injury intraperitoneally injecting with normal saline), and Sham group (normal rats intraperitoneally injecting with normal saline). Basso, Beattie, and Bresnahan (BBB) scoring system was used for evaluating behavioral outcomes. Foxp3 expression in spinal cord tissues was evaluated using immunofluorescence analysis. HE staining was used for assessing the injury of spinal cord tissues. Results: BBB scores of the Model group were remarkably lower compared to that of the Sham group (P<0.05). Foxp3 expression was significantly downregulated in the Model group compared with that of the Sham group (P<0.05). BBB scores of the BCG group were significantly higher compared to that of the Model group at 3, 5, 7, and 14 days post-treatment (P<0.05). In the BCG group, there were fewer inflammatory cells, smaller cavities, and a complete structural arrangement than in the Model group. BCG treatment significantly reduced the spinal cord injury score compared to that of the Model group (P<0.05). Post BCG treatment, Foxp3 expression was predominantly enhanced compared with that of the Model group (P<0.05). Conclusion: BCG could affect inflammation after spinal cord injury through upregulating the expression of Foxp3 and further promote the recovery of hindlimb motor function in rats with spinal cord injury.