Impact of microRNAs on the understanding and treatment of rheumatoid arthritis

Purpose of review It is becoming more and more obvious that epigenetic processes influence the development of rheumatic diseases as strongly as the genetic background. Research on the role of microRNAs (miRNAs) in rheumatic diseases, and especially in rheumatoid arthritis (RA), has been very active for the past 5 years. Most studies have reported the aberrant expression of miRNAs in the circulation or joint tissues, and the pathogenic role of a few of them has been investigated in the experimental models. Recent findings As inflammation and joint damage are the main hallmarks of RA, we focused on the three miRNAs, miR-146a, miR-155 and miR-223, whose functions have been studied in both the processes and the pathogenic role investigated in the experimental models. Summary Focusing on the role of miR-146a, miR-155 and miR-223 in RA pathogenesis emphasizes the intertwined relationships between bone homeostasis and immunity, and the prominent role of monocytes in RA. Studying the miRNAs in RA will shed light on the pathological processes and help in identifying novel drug candidates and biomarkers.