Figure 4. Expression of IDO in HGFs after stimulation with IL-17, IFN-
, or combined cytokines. HGF cultures were stimulated with indicated concentrations of IL-17, IFN-
, and combined cytokines. Culture medium was used as a control. Stimulated HGFs were harvested, and mRNA expression of IDO was analyzed by RT-PCR. GAPDH mRNA was used as an internal control. Data are representative of 4 separate experiments (A). Mean relative expression of IDO:GAPDH ± SEM from 4 separate experiments is shown (*P < 0.05, compared with the sum of IL-17 and IFN-
[1 U/mL] stimulation; **P < 0.05, compared with the sum of IL-17 and IFN-
[5 U/mL] stimulation; ***P < 0.05, compared with the sum of IL-17 and IFN-
[25 U/mL] stimulation) (B). To assess IDO activity, we determined the concentrations of kynurenine in culture supernatants. Data shown are mean concentrations of kynurenine ± SEM from 4 separate experiments (*P < 0.05, compared with the sum of IL-17 and IFN-
[1 U/mL] stimulation; **P < 0.05, compared with the sum of IL-17 and IFN-
[5 U/mL] stimulation; ***P < 0.05, compared with the sum of IL-17 and IFN-
[25 U/mL] stimulation) (C).