Fig. 1

Treatment with EC-18 ameliorated the severity of experimental arthritis. The vehicle only, tofacitinib (15 mg/kg), baricitinib (3 mg/kg), or EC-18 (250 mg/kg) was orally administered to mice once daily from day 21 after the first immunization (n = 10/group). A A graphic scheme of CIA induction and drug administration. B Arthritis development was assessed based on the arthritis score (left) and incidence (right) (n = 10/group). The severity of arthritis was assessed on a scale of 0–4 according to the criteria and incidence was calculated as 25% for one foot with arthritis symptoms. *P < 0.05, **P < 0.01, ***P < 0.001 vs. vehicle-treated control group by two-way ANOVA (Bonferroni posttests). C At 60 days after the first immunization with type II collagen (CII), sections of ankle joint tissue of subjects with the average arthritis score of each group (n = 5/group) were stained with hematoxylin and eosin (H&E) (original magnification ×40) and safranin O (original magnification ×200). Joint tissue from normal mice was used as a control. Representative histological features are shown. Two independent, blinded observers assessed the cartilage damage, inflammation, and bone damage was assessed on a scale of 0–4 according to the criteria. D At 60 days after the first immunization, serum level of IgG2a was measured via enzyme-linked immunosorbent assay (ELISA). *P < 0.05, **P < 0.01, ***P < 0.001 vs. vehicle-treated control group