Abstract:

BACKGROUND: Tumor necrosis factor (TNF) superfamily plays an important role in apoptosis. However, the role of TNF on nucleus pulposus cells remains poorly understood.
OBJECTIVE: To investigate the effects of TNF-α on apoptosis of human nucleus pulposus cell from pathways of P38MAPK and stress-activated protein kinase/c-Jun NH2-terminal kinase (JNK/SAPK).
METHODS: The human nucleus pulposus cells were cultured in vitro and randomly divided into 4 groups: TNF-α, P38MAPK inhibition, P-JNK/SAPK inhibition and control groups. The apoptosis of nucleus pulposus cells was detected by TUNEL; the expression and location of P38MAPK and P-JNK/SAPK were determined by immumofluorescence method; and the expression of P38MAPK, JNK/SAPK, and their phosphorylations were measured by Western Blot.
RESULTS AND CONCLUSION: TUNEL results showed that there was higher density of apoptotic nucleus pulposus cells in the TNF-α group than that of the other groups (P < 0.01). Immunofluorescence showed that, compared with inhibition groups and control group, the expressions of phosphorylations of P38MAPK and JNK / SAPK were increased after treatment with TNF-α (P < 0.01). Western Blot analysis also demonstrated that P38MAPK and P-JNK / SAPK were expressed and distributed mainly in cytoplasmic and nuclear, however, there was only P-JNK / SAPK expression in the TNF–α group, but no expression could be found in the inhibition groups. TNF-α induces the apoptosis of human nucleus pulposus cell via P38MAPK and JNK / SAPK pathway.