IL17A and rheumatoid arthritis: By analyzing the correlations between DAS28 and different parameters, we identified that DAS28 score positively correlated with plasma IL-22 (Fig. 6A; P < 0.0001, R = 0.8813), IL-17 (Fig. 6B; P = 0.0004, R = 0.4401) levels, and the frequencies of IL-22-producing Th cells, including Th22 (Fig. 6C; P = 0.0046, R = 0.6061), IL-22+Th1 (Fig. 6D; P = 0.0069, R = 0.3453), and IL-22+Th17 (Fig. 6E; P = 0.0012, R = 0.4094) in all RA patients before treatment.