IL17A and rheumatoid arthritis: As shown in Fig. 2, compared with that of HC, the sera of patients with RA was observed with higher levels of IFN-γ (14.98 ± 1.22, P = 0.0042), IL-4 (10.62 ± 1.43, P = 0.0006), IL-17A (34.27 ± 5.30, P < 0.0001), and IL-22 (197.00 ± 27.13, P = 0.0483) and lower level of IL-10 (5.43 ± 0.50, P = 0.043).