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Biomed Environ Sci. 2013 Apr;26(4):277-83. doi: 10.3967/0895-3988.2013.04.006.

Increase of TNFα-stimulated osteoarthritic chondrocytes apoptosis and decrease of matrix metalloproteinases 9 by NF-κB inhibition.

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  • 1Department of general surgery, Beijing Tiantan Hospital, Capital Medical University, Beijing 100050, China.



To investigate the in vitro effect of caffeic acid phenethyl ester (CAPE), a NF-κB inhibitor, on the apoptosis of osteoarthritic (OA) chondrocytes and on the regulation of the gelatinases matrix metalloproteinase 2 (MMP-2) and matrix metalloproteinase 9 (MMP-9).


Annexin V-FITC/propidium iodide (PI) labeling and western blotting were used to observe and determine the apoptosis in TNFα-stimulated primary cultured osteoarthritic chondrocytes. Also, gelatin zymography was applied to examine MMP-2 and MMP-9 activities in supernatants.


It was confirmed by both flow cytometry and western blotting that chondrocytes from OA patients have an apoptotic background. Use of CAPE in combination with 10 ng/mL of TNFα for 24 h facilitated the apoptosis. MMP-9 in the supernatant could be autoactivated (from proMMP-9 to active MMP-9), and the physiologic calcium concentration (2.5 mmol/L) could delay the autoactivation of MMP-9. The activities of MMP-2 and MMP-9 in the fresh supernatant increased significantly in response to stimulation by 10 ng/mL of TNFα for 24 h. The stimulatory effect of TNFα just on proMMP-9 was counteracted significantly by CAPE.


NF-κB could prevent chondrocytes apoptosis though its activation was attributed to the increase of proMMP-9 activity induced by TNFα (a pro-apoptotic factor). Therefore, therapeutic NF-κB inhibitor was a 'double-edged swords' to the apoptosis of chondrocytes and the secretion of MMP-9.

Copyright © 2013 The Editorial Board of Biomedical and Environmental Sciences. Published by China CDC. All rights reserved.


Apoptosis; Chondrocytes; Gelatinase; NF-κB; Tumor necrosis factor α

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