TNFSF11 and osteoarthritis: Patients with AS had significantly higher serum levels of IL-34 (878.9 ± 116.4, P < 0.01) and RANKL (155.6 ± 13.8 pg/mL, P < 0.01) than patients with osteoarthritis (626.6 ± 79.0 and 138.1 ± 15.3 pg/mL respectively) or healthy controls (612.9 ± 61.1 and 104.9 ± 15.4 pg/mL, respectively) (Figure 1).