Effect of anti-TNFα, anti-IL-1, or anti-RANKL therapy on bone mineral density. Effects of PEGylated soluble TNF receptor type I (TNFRI), IL-1 receptor antagonist (IL-1Ra) or osteoprotegerin (OPG)-Fc on areal bone mineral density (BMD) of the (a), (b) ankle and (c), (d) lumbar vertebrae. Baseline BMD measures were obtained by dual X-ray absorptiometry on the day of onset for clinical arthritis (day 0). Treatments were initiated on day 4, and final BMD was measured on day 14 post onset. Data represent means ± standard error of the means, n = 8/group. cSignificantly different from control (nonarthritic) rats, P < 0.05. vSignificantly different from vehicle (Veh)-treated arthritic rats, P < 0.05. oSignificantly different from OPG-treated arthritic rats, P < 0.05. AIA, adjuvant-induced arthritis; CIA, collagen-induced arthritis.