Background S100A12 is a calcium binding protein of extracellular receptor for advance glycation end products-binding protein (EN-RAGE). S100A12 is secreted in inflamed tissues or in the bloodstream by activated neutrophils. S100A12 mediates the proinflammatory effects on lymphocytes, endothelial cells, and neutrophils. Soluble RAGE (sRAGE) acts as a naturally occurring inhibitor of RAGE by neutralizing proinflammatory ligands including S100A12.
Objectives S100A12 and sRAGE have been suggested as biomarkers of disease activity in patients with systemic juvenile idiopathic arthritis. We investigated the clinical significance of these in adult onset Still's disease (AOSD).
Methods Blood samples were collected from 37 active AOSD patients and 38 normal controls (NC). Of the AOSD patients, follow-up samples were collected from 19 patients after resolution of disease activity.
Results Serum S100A12 (547.9±148.4 ng/mL) in AOSD patients was higher than those of NC (272.3±133 ng/mL, p<0.001). The sRAGE levels of AOSD (514.1±273.6 pg/mL) were lower than those of NC (850.3±405.8 pg/mL, p<0.001). Serum S100A12 correlated with serum sRAGE (ρ=-0.228, p=0.049). Serum S100A12 correlated with erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), ferritin, and systemic score, however the sRAGE did not correlate with any disease activity markers. In addition, S100A12 was decreased after disease activity was resolved in followed-up AOSD patients (505.7±161.3 ng/mL vs. 361.3±162.5 ng/mL, p=0.01). Furthermore, the change of S100A12 was well correlated with that of ESR, CRP, and systemic score.
Conclusions The data suggest that serum S100A12 may be a useful biomarker for evaluating disease activity in AOSD patients. Furthermore, inverse regulation of both sRAGE and its proinflammatory ligand S100A12 could contribute to promoting systemic inflammation of AOSD.
Disclosure of Interest None declared