MMP3 and rheumatoid arthritis: To assess the possibility of plasma and synovial fluid miRNAs as biomarkers of RA, we investigated the correlation of miRNAs with clinical variables including serum matrix metalloproteinase-3 (MMP-3), C-reactive protein (CRP), Erythrocyte Sedimentation Rate (ESR), 28-joint Disease Activity Score (DAS28), swollen joint count (SJC) and tender joint count (TJC).