miR-34a alleviates spinal cord injury via TLR4 signaling by inhibiting HMGB-1.

The aim of the present study was to investigate the effect of microRNA (miR)-34a on spinal cord injury (SCI)-induced inflammation and the possible underlying mechanisms. The results indicated that miR-34a expression was downregulated in a rat model of SCI compared with the control group. Furthermore, miR-34a knockdown was demonstrated to aggravate inflammation, inhibit cell proliferation and enhance apoptosis in an in vitro model of SCI. MiR-34a inhibition was demonstrated to upregulate the expression of inducible nitric oxide synthase and nitric oxide, as well as inducing the expression of toll-like receptor 4 (TLR4) and high mobility group box-1 (HMGB-1) in an in vitro model of SCI. TLR4 inhibitor reduced the effects of miR-34a downregulation on inflammation and cell growth in SCI. Together, these results suggest that miR-34a is able to alleviate SCI via inhibiting HMGB-1 expression in TLR4 signaling.