The in vitro and in vivo effects of microRNA-133a on intervertebral disc destruction by targeting MMP9 in spinal tuberculosis.

AIMS: We aim to investigate the role of microRNA-133a (miR-133a) in intervertebral disc destruction by targeting MMP9 in spinal tuberculosis (TB).

MAIN METHODS: Rabbit models with spinal TB were established and assigned to the blank, miR-133a mimic, miR-133a inhibitor and negative control (NC) groups. Primary notochordal cells were extracted and separately transfected with miR-133a mimics, miR-133a inhibitor, miR-nonsense sequence control (NC), si-NC and si-MMP9. QRT-PCR and Western blot assay were used to detect the expression of MMP-9, Collagen I, Collagen II and Collagen-X. Gelatin Zymography was performed to detect MMP9 activity. Immunohistochemistry was used to detect the expression of Collagen I, Collagen II and Collagen-X proteins. Osteoclast morphology and the number of osteoclast cells were observed after Tartrate resistant acid phosphatase staining.

KEY FINDINGS: MMP9, Collagen-X and Collagen I expression and MMP9 activity were higher while the expression of Collagen II was lower in the miR-133a mimic group than the miR-NC group. MMP9, Collagen-X Collagen I and MMP9 activities were lower and Collagen II expression was higher in the miR-133a inhibitor group than the miR-NC group. Compared with the si-NC group, the si-MMP9 group showed increased Collagen II expression but decreased expression of MMP9, Collagen-X and Collagen I and MMP9 activity. A reduced amount of osteoclast cells exhibited in the miR-133a mimic group while an increased number was seen in the miR-133a inhibitor group compared to the blank group.

SIGNIFICANCE: MiR-133a could inhibit Collagen degradation by down-regulating MMP-9 expression to attenuate the destructive effects of spinal TB on intervertebral disc.