Figure 5

Tumor necrosis factor α inhibitor treatment indirectly reduces hepcidin production in rheumatoid arthritis patients by reducing interleukin 6 levels. (A) Significant reductions in mean serum interleukin 6 (IL-6) concentrations were observed at two, four and sixteen weeks after treatment with tumor necrosis factor α (TNFα) inhibitors. (B) Effects of tocilizumab (TCZ; 25 μg/ml) and infliximab (IFX; 25 μg/ml) on hepcidin mRNA expression induced by IL-6 (10 ng/ml), TNFα (10 ng/ml), IL-1β (10 ng/ml) and their combinations in PLC/PRF/5 cells. Hepcidin mRNA was assayed by quantitative real-time PCR six hours after the stimulation. (C) IL-6 mRNA expression response to TNFα stimulation was determined in U937 cells grown in medium containing TNFα at final concentrations of 0.1, 1, 10 and 50 ng/ml. IL-6 expression increased in a dose-dependent manner. (D) Ferroportin mRNA expression response to TNFα stimulation was determined in U937 cells grown in medium containing TNFα at final concentrations of 0.1, 1, 10 and 50 ng/ml. Ferroportin expression decreased in a dose-dependent manner. The data represent means ± SD of triplicate measurements. The same experiment was repeated at least three times with consistent results, and representative data are shown. ^*P < 0.01 by paired t-test.