Zhenbao Pill reduces Treg cell proportion in acute spinal cord injury rats by regulating TUG1/miR-214/HSP27 axis

Background: Acute spinal cord injury (SCI) is one of the weakest pathologies that seriously affect the quality of life of patients. Objective: To study the mechanism of how Zhenbao Pill reduces Treg cell proportion and improves acute SCI. Methods: A rat SCI model was established. Flow cytometry analysis was performed to determine the Treg cell proportion. RNA immunoprecipitation (RIP) and RNA pull-down were applied in confirming taurine up-regulated gene 1 (TUG1) and miR-214 binding. Intrathecal injection of TUG1 siRNA was also conducted to determine the effect of TUG1 in vivo. Results: Zhenbao Pill promoted the expression of TUG1 and heat shock protein 27 (HSP27) protein, and reduced the expression of miR-214 and forkhead box protein p3 (Foxp3) as well as Treg cell proportion in a concentration-dependent manner in SCI rats or in vitro cultured CD4(+) T cells. Knockdown of TUG1 reversed the high protein expression of HSP27 and the inhibition of Treg cell proportion as well as Foxp3 protein induced by Zhenbao Pill, and miR-214 inhibitor canceled the TUG1 knockdown effect. Further, miR-214 mimic reversed the inhibition of Treg cell proportion and Foxp3 protein expression by Zhenbao Pill, which was abolished by the overexpression of HSP27. The mechanism was validated in animal experiments. Conclusion: Zhenbao Pill regulated TUG1/miR-214/HSP27 signaling pathway to reduce Treg cell proportion and thus relieve acute SCI.