Comparisons between miRNA concentrations in plasma and those in synovial fluid. A and B, Plasma and synovial fluid concentrations of miR-16, miR-132, miR-146a, miR-155 and miR-223 in RA (A) and OA (B). The average concentrations of these miRNAs were quite different. Significant differences between plasma and synovial fluid are indicated by * = P < 0.05, ** = P < 0.01.