Clinical Significance of Myeloid-Related Protein 8/14 as a Predictor for Biological Treatment and Disease Activity in Rheumatoid Arthritis.

Objectives: To investigate the serum level of Myeloid-Related Protein 8/14 complex (MRP8/14) and to predict and monitor the response to biologic treatment in rheumatoid arthritis (RA) patients.

Methods: Each patient underwent clinical examination and blood sampling for assessment of serum high-sensitivity C-reactive protein (hs-CRP) levels, erythrocyte sedimentation rate (ESR), rheumatoid factors (RF), anti-cyclic citrullinated protein antibodies (anti-CCP), and serum concentrations of MRP8/14 protein complexes (myeloid-related proteins, MRP8/14) were measured at baseline, and weeks 4 and 12 (after initiation of treatment).

Results: Serum MRP8/14 protein complex levels correlated with DAS28 and anti-CCP antibody. MRP8/14 protein complex levels decreased significantly after 12 weeks treatment with biological therapy: mono-rhTNFR-Fc active group. rhTNFR-Fc plus methotrexate (MTX) decreased MRP8/14 protein complex levels from 11839±1849 ng/ml to 5423±1130 ng/ml (<0.01) a reduction of 54.2% compared with 32.9% in the rhTNFR-Fc group.

Conclusions: MRP8/14 protein complex levels were increased in active stage RA patients. MRP8/14 levels were decreased with rhTNFR-Fc treatment, suggesting serum concentrations of MRP8/14 protein complex might be a promising biomarker to predict responses to biological therapy in active RA patients at baseline and could be used to monitor responses to treatment across different mechanisms of action.