Effect of interleukin-6 on apoptosis of human nucleus pulposus cells.

[Objective]To investigate the effects of IL-6 on apoptosis of human nucleus pulposus cells.[Methods]The human nucleus pulposus cells were cultured.The cells were divided into 4 groups at random:the group treated with IL-6,the group treated with IL-6+20μmol/L SB203580,the group treated with IL-6 +20μmol/L SP600125 and the control group.The density of human nucleus pulposus cells of apoptosis was detected by flow cytometric assay and TUNEL method for each group.The expression and cellular localization of P-P38MAPK and P-JNK/SAPK were investigated by immunohistochemistry.The expression of total JNK /SAPK,P38MAPK and their phosphorylations were investigated by Western blotting.[Results]There was higher density of human nucleus pulposus cells of apoptosis in IL-6 group than that in the control group and those in inhibition groups(P0.01).The expression of phosphorylations of P38MAPK and JNK /SAPK was increased after treatment with IL-6.The expression of phosphorylations of P38MAPK or JNK /SAPK was significantly inhibited after pretreatment with SB203580 or SP600125 compared with that in the IL-6 group in immunofluorescence analysis and Western blotting.Immunofluorescence analysis also demonstrated that P-P38MAPK and P-JNK/SAPK were expressed and distributed mainly in cytoplasm and nucleus,however,no P-P38MAPK and P-JNK/SAPK in the control group.[Conclusion]IL-6 induces the apoptosis of human nucleus pulposus cells via P38MAPK and JNK/SAPK pathway.