When treating the symptoms of juvenile idiopathic arthritis, also called juvenile idiopathic arthritis (JIA), disease-modifying anti-rheumatic drugs (DMARDs) and anti-tumor necrosis factor (TNF) are often used. These include methotrexate (MTX), Enbrel and Humira.

Around one-third of patients with juvenile idiopathic arthritis fail to respond to MTX or TNF therapy. Even fewer achieve the American College of Rheumatology Pediatric 70% criteria for response.

In this new research, printed in The Journal of Rheumatology in January 2018, the researchers evaluated whether measuring blood levels of the protein S100A12 could be a suitable predictor for treatment outcomes in JIA patients.

Because change in serum S100-protein myeloid-related protein complex 8/14 (MRP8/14) is associated with therapeutic response, we tested granulocyte-specific S100-protein S100A12 as a potential biomarker for treatment response.

Methods
S100A12 serum concentration was determined by ELISA in 163 patients treated with MTX or anti-TNF at baseline and follow up. Treatment response achievement of inactive disease, and improvement in Juvenile Arthritis Disease Activity Score were recorded. ELISA is enzyme-linked immunosorbent assay - a test that uses antibodies and color change to identify a substance.

Results
Researchers found that when compared to non-responders, patients who responded to the administrated therapies had significantly higher baseline levels of blood S100A12.

Conclusion
People who will respond to MTX or anti-TNF treatment can be identified by pre-treatment S100A12 serum concentration levels.