The butyrate treatment alleviated arthritis severity.IL-1β, IL-6, and IL-17A were significantly downregulated in the butyrate group. In contrast, butyrate upregulated the mRNA expression level of IL-10 in synovial tissues.Butyrate promoted the polarization of Treg but not Th17 cells. The gene discussed is IL17A; the disease is arthritic joint disease.