Abstract: Abstract：Objective To investigate the expression of TWEAK and Fn14 in nucleus pulposus of human degenerated lumbar discs and evaluate their clinical significance. Methods The mRNA and protein expression of TWEAK and Fn14 in the experimental group（30 fresh pulpy nucleus of patients with lumbar disc herniation)and the control group(10 fresh pulpy nucleus of patients with traumatic lumbar vertebrae) were detected by semi-quantitative RT-PCR and immunohistochemical staining. Results The mRNA expression of TWEAK was significantly higher in the experimental group when compared with that of the control group( 0.949士0.0931 VS 0.653士0.110 ,P＜0.01); It was same to TWEAK protein (0.682士0.126 VS 0.397士0.057 ,P＜0.01); Fn14 mRNA (0.936士0.125 VS 0.632士0.059,P＜0.01); and Fn14 protein (0.540士0.051 VS 0.344士0.072 ,P＜0.01). Conclusions The increased expression of TWEAK and Fn14 in degenerate lumbar discs indicates that TWEAK and Fn14 may be involved in the process of lumbar intervertebral disc degeneration（IDD）.

Key words: tumor necrosis factor-like weak inducer of apoptosis, fibroblast growth factor-inducible 14, intervertebral disc