RESUMO
Objective To observe the expression of aggrecanase 2 and a tissue inhibitor of metalloproteinase 3 (TIMP-3) in degenerate human lumbar intervertebral discs and their role in degeneration of the nucleus pulposus.Methods Pfirrmann classification was used to class degenerate intervertebral discs observed through MRI.They were divided into three groups:a control group (Pfirrmann grade Ⅰ-Ⅱ),a degeneration group (Pfirrmann grade Ⅲ-Ⅳ),and a severe degeneration group (Pfirrmann grade Ⅴ).A total of 45 cases accepted lumbar spine surgery for removing nucleus pulposus specimens.Each group contained 15 cases.After formalin-fixation and paraffin embedding,immunohistochemistry was used to detect aggrecanase 2 and TIMP-3 expression in the nucleus pulposus cells.Results The percentages of cells positive for aggrecanase 2 were (13.58 ± 7.76) ％,(33.48 ± 13.95) ％ and (56.00 ± 18.39) ％ in the control,degeneration and severe degeneration groups respectively.These differences had statistical significance.The percentages of cells positive for TIMP-3 were (34.78 ± 13.80) ％,(46.77 ± 10.98) ％ and (50.65 ± 16.45) ％,and these differences were again statistically significant.The aggrecanase 2/TIMP-3 ratios were also significantly different.Conclusion As the degree of degeneration of the nucleus pulposus increased,the expression of aggrecanase 2 and TIMP-3 rose,which indicates that both changes were closely connected with the degeneration.Their ratio was correlated with the degree of degeneration of the nucleus pulposus.