Bone active resorption. A and B, Representative sections of the bone-pannus interface region with cathepsin K-positive cells shows bone resorbing activity in chronic antigen-induced arthritis (AIA) rabbits (A) and HFD + AIA rabbits (B), original magnification x200, scale bar = 50 µm. C, Illustration of the region of interest evaluated in each femoral condyle at the posterior bone-pannus interface region. Contact surface and invasive areas were analysed in hematoxylin and eosin (H-E) stained sections and then photographed in chronic antigen-induced arthritis (AIA) rabbits (upper sections) and HFD + AIA rabbits (lower sections) (left side: H-E stained sections, right side: photographed sections, original magnification x400, scale bar = 100 µm). D, Densitometric analysis of cathepsin K-positive staining in the synovium of both groups of animals. Bars show the mean and SEM (n = 7 to 9 rabbits per group). E and F, Densitometric analysis of contact surface and invasive areas of AIA and HFD + AIA rabbits. White bars correspond to AIA group and black bars to AIA + HFD group; both show the mean and SEM (n = 7 to 9 rabbits per group).