Ligustrazine Prevents Intervertebral Disc Degeneration Via Suppression Of Aberrant Tgf Beta Activation In Nucleus Pulposus Cells

Objectives. Aberrant transforming growth factor beta (TGF beta) activation is detrimental to both nucleus pulposus (NP) cells and cartilage endplates (CEPs), which can lead to intervertebral disc degeneration (IDD). Ligustrazine (LIG) reduces the expression of inflammatory factors and TGF beta 1 in hypertrophic CEP to prevent IDD. In this study, we investigate the effects of LIG on NP cells and the TGF beta signaling. Design. LIG was injected to the lumbar spinal instability (LSI) mouse model. The effect of LIG was evaluated by intervertebral disc (IVD) score in the LSI mouse model. The expression of activated TGF beta was examined using immunostaining with pSmad2/3 antibody. The upright posture (UP) rat model was also treated and evaluated in the same manner to assess the effect of LIG. In ex vivo study, IVDs from four-week old mice were isolated and treated with 10(-5), 10(-6), and 10(-7) M of LIG. We used western blot to detect activated TGF beta expression. TGF beta-treated human nucleus pulposus cells (HNPCs) were cotreated with optimized dose of LIG in vitro. Immunofluorescence staining was performed to determine pSmad2/3, connective tissue growth factor (CCN2), and aggrecan (ACAN) expression levels. Results. IVD score and the percentage of pSmad2/3+ NP cells were low in LIG-treated LSI mice in comparison with LSI mice, but close to the levels in the Sham group. Similarly, LIG reduced the overexpression of TGF beta 1 in NP cells. The inhibitory effect of LIG was dose dependent. A dose of 10(-5) M LIG not only strongly attenuated Smad2/3 phosphorylation in TGF beta-treated IVD ex vivo but also suppressed pSmad2/3, CCN2, and ACAN expression in TGF beta-treated NP cells in vitro. Conclusions. LIG prevents IDD via suppression of TGF beta overactivation in NP cells.