Fig. 1.

Commensal bacteria-derived butyrate ameliorates autoimmune arthritis

(a) The faecal concentration of acetate, propionate, and butyrate in healthy control and new-onset untreated rheumatoid arthritis (NORA) subjects (n= 41, 31).

(b-e) CIA incidence (b, d) and arthritis scores after booster immunization (c, e) in CIA mice fed the control HAMS, or HAMSB diet (n= 13–15; mean ± s.e.m. b, c), and CIA mice fed the control HAMS, HAMSA or HAMSP diet (n= 12; mean ± s.e.m. d, e). AUC was calculated in each mice for c, e.

(f) Arthritis scores for SKG mice fed the control HAMS or HAMSB diet after laminarin injection (n= 11; means ± s.e.m.). AUC was calculated in each mice.

(g–i) Micro-computed tomography (mCT) analysis of the calcaneus in ankle joint four weeks after booster immunization in CIA mice fed the control HAMS or HAMSB diet (n= 5). Representative mCT images (g). The eroded area is shown in Red. Scale bars: 1 mm. Eroded surface per bone surface (h,%) and eroded volume per bone volume (i,%).

Results show one representative experiment of at least two experiments for mouse study. *P< 0.05, **P< 0.01, ***P< 0.001 (A, Mann-Whitney test; c, f, h, i, Welch's t-test or unpaired two-tailed Student's t-test; b, d, Log-rank test; e, one-way ANOVA followed by Tukey's post-hoc test.