Efficacy of MRP8/14 as a Marker of Disease Activity in Rheumatoid Arthritis

Objective: Early and accurate evaluation of the presence and activity of synovitis is extremely important in the diagnosis and treatment of rheumatoid arthritis. Myeloid related protein 8/14 (MRP8/14), also known as calprotectin or S100A8/A9 is considered as a sensitive marker for local inflammatory activity in rheumatoid arthritis. The aim of this study is to demonstrate the efficacy of MRP8/14 as a marker of disease activity in RA. Methods: Thirty-one patients with diagnosis of RA who received treatment without biological drugs at our institution were included in this study. Serum MRP8/14, CRP and MMP-3 were tested in all patients. Disease activity was evaluated using DAS28-CRP and SDAI. Ultrasonography was performed on the wrists and MCP joints of both hands using semi-quantitative scale of power Doppler signal. The sum of scales in joints was calculated as the PD score. The correlation of MRP8/14 with serum biomarkers, disease activity and ultrasonography examination was investigated. Result: Serum MRP8/14 was strongly correlated with CRP (r = 0.63) and MMP-3 (r = 0.69). A correlation was observed between serum MRP8/14 and DAS28-CRP (r = 0.53) and SDAI (r = 0.66). No significant correlation was found between PD scores and MRP8/14. Conclusion: This study demonstrated that MRP8/14 is correlated with evaluated disease activity and markers of serum inflammatory response in patients not using biological drugs. MRP8/14 is considered an effective new method for objective evaluation of synovitis in RA.