Effects of Dex on GAG loss and chondrocyte biosynthesis in bovine cartilage treated with combinations of mechanical injury, TNFα and IL-6/sIL-6R. A) Percentage of GAG loss in bovine cartilage in response to six-day treatments. The mean ± SEM total GAG content was 466.3 ± 21.5 μg GAG/disk in the untreated control group. 10 nM DEX significantly reduced GAG loss from conditions involving TNFα plus IL-6/sIL-6R, mechanical injury or both. B) Chondrocyte biosynthetic rates measured by 35S-sulfate incorporation during days 4 to 6. TNFα, either with or without IL-6/sIL-6R and mechanical injury, significantly lowered biosynthesis of proteoglycan, while the addition of DEX to these conditions blocked the biosynthesis reductions. Values in A and B are presented as mean ± SEM. N = 10 cartilage disks in no-treatment control, DEX, TNFα, and DEX + TNFα conditions. N = 5 cartilage disks in the remaining conditions.* = P < 0.05 (only comparisons from selected hypothesis are shown). DEX, dexamethasone; GAG, glycosaminoglycans; IL-6, interleukin-6; SEM, standard error of the mean; sIL-6R, soluble interleukin-6 receptor; TNFα, tumor necrosis factor alpha.