Pediatric Rheumatology Online Journal → June 2003 → Health-Related Quality of Life, Disease Activity and Outcome Assessments→ Abstract #35

S100A12 (EN-RAGE) IS A UNIQUE SERUM MARKER FOR DISEASE ACTIVITY IN JUVENILE IDIOPATHIC ARTHRITIS

D. Foell,¹ I. Hammerschmidt,¹ H. Wittkowski,¹ M. Frosch,¹ T. Vogl,² J. Roth.¹

¹Department of Pediatrics, University of Muenster, Muenster, Germany; ²Institute of Experimental Dermatology, University of Muenster, Muenster, Germany

Remission can be induced in most of the patients with juvenile idiopathic arthritis (JIA) using combined anti-inflammatory treatment. However, about half of the patients have relapses after discontinuation or reduction of therapy. To date, we have no means to identify clinically inactive patients at special risk for relapses. S100A12 exhibits pro-inflammatory properties via interaction with the multiligand receptor for advanced glycation end products (RAGE). We investigated S100A12 in oligo- and polyarticular JIA, and analyzed the correlation of its serum levels with disease activity. We analyzed S100A12 in patients in remission and looked for its predictive value for the risk of relapses.
Methods: S100A12 serum concentrations were determined in 37 healthy controls and 63 patients with JIA. 48 patients were followed up over a mean time of 2.8 years (0.5 6.9). S100A12, CRP and ESR were analyzed. All in all 344 serum samples were obtained. We correlated serum markers with ACR criteria for disease activity.
Results: Mean S100A12 serum level in healthy controls was 50 (SEM 4) ng/ml. Samples from JIA patients in active disease revealed a mean level of 385 (36) ng/ml.. There was a strong correlation of S100A12 to active joints count (r=0.46;p0.001). The mean S100A12 serum levels of 25 relapsers were higher (mean 141 ng/ml) than serum levels of non-relapsers (mean 74 ng/ml). Likelihood ratio (LR+) for the risk of relapse in the presence of S100A12 levels above 90 ng/ml was 2.6. CRP and ESR showed no differences between both groups.
Conclusions: Our study indicates that S100A12 is a potent biological marker for the disease activity of oligo- and polyarticular JIA. Moreover, it could serve as predictive serum marker for stable remission in clinically inactive JIA, thus helping to decide about tapering or withdrawing medication. On the other hand, higher levels might point to patients at special risk for occult disease activity even in the absence of other abnormal observations.