IL-4 Can Inhibit IL-17 Production in Collagen Induced Arthritis

Background: IL-4 is a cytokine that induces differentiation of naive helper T cells into Th2 cells. Once activated by IL-4, Th2 cells subsequently produce additional IL-4. Objective: To examine the effect of IL-4 on IL-17 production and its effect in Collagen- Induced Arthritis (CIA) mice. Method: In this study, a chicken collagen-II-induced experimental arthritis (CIA) model was used in DBA/1 mice to investigate the relationship between IL-4 and IL-17 as well as other inflammatory factors. On the 38th day after the mice were induced with CIA, the expression of IL-17 and IL-4 as well as IFN-γ and IL-13 in sera of the mice was measured by QRT-PCR and ELISA. Result: The result of QRT-PCR analysis of IL-17 and IL-4 mRNA levels in the spleen showed that IL-17 is increased significantly at the onset of CIA in the spleen (p<0.01). Meanwhile, IL-17 is generally reduced at the peak of CIA but IL-4 is increased significantly at this peak in the spleen (p<0.05) when the weight of the animal was taken into consideration. Conclusion: IL-4 can be involved in the production of IL-17 at especially the peak of CIA. These results imply that the inhibition of IL-17 may decrease the expression of IL-1β and IL-6 production which will result in the aggravation of arthritis.