Research Paper Volume 11, Issue 22 pp 10513—10531

Astaxanthin protects against osteoarthritis via Nrf2: a guardian of cartilage homeostasis

Figure 4. Nrf2 signaling mediated protective effects of Ast on OA chondrocytes. Chondrocytes were cultured with vehicle or Ast (5, 10 and 20 μM) for 2 h, then stimulated with IL-1β (5 ng/ml), TNF-α (5 ng/ml) or TBHP (100 μM). (AC) Levels of Nrf2 signaling pathway proteins, including Nrf2, HO-1, and NQO1 were determined by western blotting and quantified. To knock down Nrf2 expression, chondrocytes were transfected with Nrf2 siRNA using Lipofectamine 3000. (D) Transfection efficiency was evaluated by detecting Nrf2 expression using western blotting. After 24h of transfection, chondrocytes were treated with vehicle or Ast (10 μM) for 2 h followed by stimulation with IL-1β (5 ng/ml) for 24 h. (E, F) The expression of Collagen II, ADAMTS5, MMP3, and MMP13 was measured by western blotting and quantified. The data are presented as dot plots from three independent experiments. Significant differences among different groups are indicated as *p<0.05 vs. control; **p<0.01 vs. control; ***p<0.001 vs. control; ****p<0.0001 vs. control. #p < 0.05 vs. IL-1β or TNF-α or TBHP group; ##p < 0.01 vs. IL-1β or TNF-α or TBHP group; ###p < 0.001 vs. IL-1β or TNF-α or TBHP group; ####p < 0.0001 vs. IL-1β or TNF-α or TBHP group. &p < 0.05 vs. (IL-1β or TNF-α or TBHP) + Ast group; &&p < 0.01 vs. (IL-1β or TNF-α or TBHP) + Ast group; &&&p < 0.001 vs. (IL-1β or TNF-α or TBHP) + Ast group.