Figure 5. As₂O₃ inhibited histological damage in joints of CIA mice.

A. Hematoxylin and eosin staining of hind leg knee joint sections demonstrated no histological damage in normal control group (I), whereas synovial hyperplasia, pannus formation, massive joint destruction were observed in the knee joints of CIA control mice (II). CIA mice treated with MTX 1.5 mg/kg/week (VI) and As₂O₃ at doses of 1.0 mg/kg/day (III), 2.0 mg/kg/day (IV), and 5.0 mg/kg/day (V) demonstrated significantly diminished joint destruction, and this was particularly applied to CIA mice treated with MTX and As₂O₃ at doses of 2.0 and 5.0 mg/kg/day. Original magnification = ×4. B. Histological scores of CIA control mice (n = 6) increased significantly compared to normal control group (n = 6, p value not shown). CIA mice treated with MTX 1.5mg/kg/week (n = 6) and As₂O₃ at doses of 2.0 mg/kg/day (n = 6) and 5.0 mg/kg/day (n = 6) showed significant decrease in histological score compared to CIA control group (n = 6, *p < 0.05, **p < 0.01). Data are expressed as the mean ± S.E.M. NC = normal control mice. Con = CIA control mice. MTX = methotrexate.