Fig. 1.

P. copri RA colonization exacerbated arthritis. A Illustration of the colonization experiments with P. copri RA (PC) and B. thetaiotamicron (BT). B Confirmation of P. copri RA and B. thetaiotamicron colonization by agarose gel electrophoresis. gPC indicates P. copri genomic DNA (gPC), and B. thetaiotaomicron genomic DNA (gBT) was used as a positive control; PC, BT, and CON represent total bacterial DNA exacted from the feces of the corresponding group; M, DNA ladder. C Clinical scores of collagen-induced arthritis in the PC (n = 4), BT (n = 4) and CON (n = 3) groups. D Serum anti-bovine type II collagen IgG level. E Representative histology of joints. The black arrow indicates synovial lining-cell hyperplasia, and the blue box indicates stromal cells. F Histological scores of joints. G Levels of fecal IgA. H Serum LPS levels. Each symbol in (D, F, G, and H) represents an animal. Error bars indicate the SEM (C, D, F–H). P values were determined by two-way ANOVA (C), one-way ANOVA (D, F, G, H). *p < 0.05, **p < 0.01, ***p < 0.001, ^#p < 0.05, ^##p < 0.01, ^###p < 0.001