DKK1 and enthesitis-related juvenile idiopathic arthritis: As shown in Figure 2A, ERA patients showed significantly higher plasma levels of IL-6 (21.04 ± 40.80 pg/ml) and OPG (4.31 ± 2.25 pmol/L) and lower plasma levels of DKK1 (37.02 ± 32.86 pmol/L) than HC (IL-6: 2.51 ± 1.63 pg/ml, p = 0.0006; OPG: 2.65 ± 2.11 pmol/L, p = 0.0002; DKK1: 55.48 ± 32.70 pmol/L, p = 0.0048), whereas RANKL plasma levels were comparable.