Figure 4.

Autophagy inhibition abrogates the anti-inflammatory and chondroprotective effects of curcumin in inflammatory chondrocytes. Chondrocytes were pretreated with or without curcumin (20 µM) for 2 h, followed by treatment with or without H₂O₂ (20 µM) for 24 h. Chondrocytes were then treated with 3-MA (50 nM), curcumin (20 µM) or 3-MA+curcumin. (A) IL-1β, (B) IL-6 and (C) iNOS mRNA expression was measured by reverse transcription-quantitative PCR. GAPDH was used as an internal control. (D and E) IL-1β, IL-6 and iNOS protein expression was determined using western blot analysis. (D) Representative western blot and (E) quantified protein levels. (F) The production of IL-1β and IL-6 was detected by ELISA. Values are expressed as the mean ± standard deviation (n=3). One-way ANOVA followed by Tukey's post-hoc test was used for statistical analysis. ^*P<0.05, ^**P<0.01, ^***P<0.001, ^****P<0.0001 vs. H₂O₂ treatment group; ^##P<0.01, ^###P<0.001 vs. curcumin + H₂O₂ treatment group. iNOS, inducible nitric oxide synthase; 3-MA, 3-methyladenine.