Background: Evaluation of disease activity in children with Juvenile Idiopathic Arthritis (JIA) is primarily based on clinical examination and conventional parameters of inflammation. But, in daily clinical practice, these two findings often fail to be in accord, making therapeutic decisions difficult. The aim of our research was to evaluate the potential usefulness of IL-6, IL-1alpha and TNF-alpha in monitoring disease activity and severity in JIA.
Methods: In a 2-year prospective study, IL-6, IL-1alpha, and TNF-alpha levels were measured using ELISA in 63 serum samples for 40 JIA patients. The control population consisted of 18 healthy children. The data were correlated with disease activity and severity (quantified with JADAS-27 composite score).
Results: The patients with active disease had greater IL-6 levels than did the patients with inactive disease [47.2 pg/mL (2 to 578.7) vs. 2.6 pg/mL (2 to 8.3); p = 0.002] and controls [47.2 pg/mL (2 to 578.7) vs. 2.25 pg/mL (2 to 4); p = 0.006]. Differences between active disease and remission were also significant for every JIA subgroup. The cutoff value for IL-6 in the diagnosis of active disease obtained from the ROC curve analysis was 8.33 pg/mL. Levels of circulating IL-6 were elevated in patients with severe and moderate disease activity (JADAS-27 score > 10) compared with those of low disease activity (JADAS-27 score < or = 10) [80.1 pg/mL (2 to 578.7) vs. 7.41 (2 to 69); p = 0.010]. We found no correlation of serum TNF-alpha and IL-1alpha levels with disease activity in our patients. The most elevated levels of serum TNF-alpha were found in patients during clinical remission with Etanercept.
Conclusions: Serum IL-6 concentrations may serve as a biomarker of disease activity and severity in JIA, providing additional information in certain clinical situations with great discrepancy between clinical assessment and conventional laboratory tests. Upon treatment with Etanercept, although many JIA patients reached remission on medication, they developed increased circulating TNF-alpha levels.