Methotrexate ameliorates pristane-induced arthritis by decreasing IFN-γ and IL-17A expressions

Objective: This study was carried out to test the effects of methotrexate (MTX) and black seed oil (BSO) on pristane-induced arthritis (PIA) in rats. Methods: Inbred dark agouti (DA) rats were induced by a single subcutaneous injection of pristane, and then treated with MTX or BSO. Arthritis severity was evaluated macroscopically and microscopically. Plasma nitric oxide (NO) concentration was determined by the Griess method and cytokine mRNA expression in the spleen was detected by the real-time reverse transcription-polymerase chain reaction (RT-PCR). Results: The clinical arthritis severity was decreased after MTX treatment, while the BSO groups did not show significant changes compared with the disease group. The plasma NO level of the MTX group was significantly decreased compared with the disease group, but the BSO groups showed no difference from the disease group in plasma NO levels. The interferon-γ (IFN-γ) and interleukin-17A (IL-17A) mRNA expressions in the spleens were significantly decreased in the MTX group, but only showed a declining trend in the BSO groups compared with the disease group. Neither MTX nor BSO had an effect on the mRNA expressions of IL-4, transforming growth factor β (TGF-β), and tumor necrosis factor-α (TNF-α) in the spleen. Conclusions: MTX, but not BSO, can reduce the arthritis severity and decrease the mRNA expressions of IFN-γ and IL-17A in pristane-induced arthritis of rats.