Fig. 6

Catabolic effect of TNFα is partially mediated by ROS in AF cells. a Flow cytometry showed that ROS levels were significantly increased in AF cells after treatment with TNFα. b Reporter activity of the OKD48 construct was significantly induced by treatment with TNFα (10 and 50 ng/ml) in AF cells. c Real-time RT-PCR analysis. Treatment of NAC significantly attenuated TNFα-mediated induction of COX-2 mRNA expression and reduction of aggrecan in AF cells. Data presented as mean ± SD of three independent experiments performed in triplicate (n = 3). d α-Tocopherol significantly reduced MMP-3 mRNA expression and restored aggrecan mRNA expression in the TNFα-treated cells. Data presented as mean ± SD of five independent experiments performed in triplicate (n = 5). e Western blotting. NAC treatment inhibited the phosphorylation of p38, ERK, JNK, and p65 in TNFα-treated AF cells. *p <0.05. COX cyclooxygenase, ERK extracellular signal-regulated kinase, HPRT hypoxanthine phosphoribosyl transferase, JNK c-Jun N-terminal kinase, MMP matrix metalloprotease, NAC N-acetyl cysteine, ns not significant, TNF tumor necrosis factor