Figure 4.

Effects of recombinant PGRN on chondrocytes catabolism induced by TNFα. a and b, chondrocytes were cultured in the presence of graded concentrations of recombinant PGRN (0–200 ng/ml) for 48 h. At the end of the culture period, the expression of MMP13 and ADAMTS5 were analyzed by Western blotting and real-time PCR. One-way ANOVA and Tukey's multiple comparison test. c and d, chondrocytes were treated with or without 10 ng/ml TNFα for 24 h, PGRN expression and secretion were detected by real-time PCR and ELISA. Unpaired two-tailed Student's t tests. e, the activity of SIRT1 was detected in chondrocytes treated with or without 10 ng/ml TNFα for 48 h. One-way ANOVA and Tukey's multiple comparison test. f and g, chondrocytes were cultured in the absence or presence of 100 ng/ml PGRN and combination with or without 10 ng/ml TNFα for 48 h, levels of MMP13 and ADAMTS5 were analyzed by Western blotting and real-time PCR. Brown-Forsythe and Welch ANOVA test with Dunnett's T3 multiple comparison test. h and i, chondrocytes were treated with 10 ng/ml TNFα, transfected with control siRNA or SIRT1 siRNA cultured in the absence or presence of 100 ng/ml PGRN. The expression of MMP13 and ADAMTS5 was detected by Western blotting and real-time PCR. One-way ANOVA and Tukey's multiple comparison test. Data were expressed as mean ± S.D. in each scatter plot. *, p < 0.05; **, p < 0.01; ***, p < 0.001.