Figure 5

Histologic analysis of bone erosions in mice with collagen-induced arthritis (CIA) after treatment with IFN-β. Mice were treated with the indicated concentrations of IFN-β for 7 days starting when the first clinical signs of arthritis were observed. Hind paws were taken for histology. (a) Bone erosions were scored in a blinded manner on a scale of 0 to 4 as described in Materials and methods. A significant reduction in bone erosions was observed in the animals treated with 2.5 μg and 1.25 μg IFN-β per injection/mouse in comparison with controls (P = 0.02); results are means ± SEM. Immunohistochemical analysis of the number of cells positive for RANKL (receptor activator of NF-κB ligand) and c-Fos after 7 days of IFN-β treatment in CIA mice. Sections were scored on a 4-point scale. (b) RANKL staining; a decrease of RANKL-positive cells was observed in the group of animals treated with 2.5 μg IFN-β, although not statistically significant (P = 0.07). (c) c-Fos staining; the number of c-Fos-positive cells was significantly reduced in the mice treated with daily 2.5 μg per injection IFN-β (P = 0.04). *Statistically significant difference. SEM, standard error of the mean.