Research Paper Volume 11, Issue 22 pp 10513—10531

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

Figure 5. Effects of Ast on IL-1β-induced inflammatory response. Chondrocytes were treated with Ast (5, 10, and 20 μM) for 2 h followed by stimulation with vehicle or IL-1β (5 ng/mL) for 24 h. (A) Expression of iNOS and COX-2 protein assessed by western blotting and quantified. (B) To detect altered phosphorylation within the MAPK signaling pathway, chondrocytes were serum-starved for 6 h followed by treatment with vehicle or Ast (5,10, and 20 μM) for 2 h. Cells were then stimulated with IL-1β (5 ng/mL) for 30 min. MAPK activation was examined using western blotting and quantified. (C) Phosphorylation of ERK was detected by western blotting after chondrocytes were pre-treated with vehicle or PD0325901 (a MEK inhibitor) for 2 h, followed by stimulation with IL-1β (5 ng/ml). (D) Chondrocytes were treated as indicated for 24 h. The expression of COX2, Collagen II, and MMP3 was determined using 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 group; ##p < 0.01 vs. IL-1β group; ###p < 0.001 vs. IL-1β group; ####p < 0.0001 vs. IL-1β group.