Serum S100A12 may be a useful biomarker of disease activity in adult-onset Still's disease
S100A12 and soluble receptor for advanced glycation endproducts (sRAGE) have been suggested as biomarkers of disease activity in patients with systemic juvenile idiopathic arthritis. We investigated the clinical significance of these markers in adult-onset Still's disease (AOSD). Blood samples were collected from 37 patients with active AOSD and 38 healthy controls (HC). Of the patients with AOSD, followup samples were collected from 19 patients after resolution of disease activity. Serum S100A12 (547.9 ± 148.4 ng/ml) in patients with AOSD was higher than those of HC (272.3 ± 133 ng/ml, p < 0.001). The sRAGE levels of AOSD (514.1 ± 273.6 pg/ml) were lower than those of HC (850.3 ± 405.8 pg/ml, p < 0.001). Serum S100A12 correlated with serum sRAGE (r = -0.228, p = 0.049). Serum S100A12 correlated with erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), ferritin, and systemic score, whereas sRAGE did not correlate with any disease activity markers. In addition, the level of S100A12 was decreased after disease activity was resolved in followed-up patients with AOSD (505.7 ± 161.3 ng/ml vs 361.3 ± 162.5 ng/ml, p = 0.01). Further, the change of S100A12 was well correlated with that of ESR, CRP, and systemic score. S100A12 levels showed strong correlations with known disease activity markers such as ESR, CRP, ferritin, and systemic score. In the followup patients with AOSD, most patients showed decreased S100A12 levels after resolution of disease activity. These results suggest that serum S100A12 can be a reliable clinical marker for monitoring disease activity and treatment response.