Fig. 6. Butyrate suppresses immune responses and reduces joint inflammation and bone destruction in mice.

(A) Scheme of the experimental design for a butyrate-based preventive regimen using the classic CIA mouse model of RA. (B and C) Arthritis incidence and scores in CIA mice with or without butyrate (But) supplementation. CIA, n = 19; But, n = 19. (D) Arthritis and bone erosion of the paws by images of micro-CT (top and middle) and hematoxylin and eosin (H&E)–stained (bottom) analysis. (E) Histopathological scoring of the paws. Con, control. Scale bars, 200 μm. n = 10 per group. (F to H) Concentrations of serum IL-10 (F), IL-6 (G), and anti–collagen type II (CII) antibody (H). n = 19 per group. (I to L) Representative flow cytometry plots with graphs showing the frequency of CD4⁺CD44⁺CD25⁺Foxp3⁺ T_regs (I and J) and CD4⁺CD44⁺CXCR5⁺PD1⁺Bcl6⁺ T_FH cells (K and L). Con, n = 9; CIA, n = 8 to 14; But, n = 8 to 14. Data were pooled from two independent experiments and are here expressed as means ± SEM. Significance was determined using Kaplan-Meier analysis with log-rank test (B), two-way ANOVA followed by Tukey’s multiple comparisons test (C), or Mann-Whitney U test (E-L). *P < 0.05 and **P < 0.01.