Figure 1
TNF-α and IL-1β protect chondrocytes from sodium-nitro-prusside (SNP)–induced cell death. A, Isolated chondrocytes were pretreated with different concentrations of TNF-α (10–30 ng/ml) for 24 hours. SNP at the indicated concentrations was then added for an additional 24 hours. Cell survival was estimated by 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) test, and results were expressed as percent of surviving cells compared with control nontreated cells (100%). *a, Statistically different from the nontreated control (p < 0.05); *b, statistically different from SNP-treated cells in the absence of TNF-α (p < 0.05). B, Chondrocyte survival after 30 minutes to 18 hours of TNF-α (10 ng/ml) pretreatment, followed by 24 hours of SNP treatment. *a, Statistically different from the nontreated control (p < 0.05); *b, statistically different from SNP-treated cells in the absence of TNF-α (p < 0.05). C, Experiment was performed as in A, except that cells were pretreated with IL-1β (5 ng/ml) instead of TNF-α. *a, Statistically different from the nontreated control (p < 0.05); *b, statistically different from SNP-treated cells in the absence of IL-β (p < 0.05). D, Cartilage explants were pretreated with TNF-α (10 ng/ml) for 24 hours. SNP (0.5 mm) was then added for an additional 24 hours. Cell survival was determined as in A. *a, Statistically different from the nontreated control (p < 0.05); *b, statistically different from SNP-treated cells in the absence of TNF-α (p < 0.05).
