Altered expression of microRNAs may predict therapeutic response in rheumatoid arthritis patients

Background: Epigenetic alternations of microRNAs (miRNAs) can contribute to the pathogenesis and progression of rheumatoid arthritis (RA). This study aimed to measure the expression level of peripheral blood miRNAs, as well as their target mRNAs, in RA patients and healthy controls (HCs), and to evaluate the potential of miRNAs as promising non-invasive biomarkers of treatment response. Methods: The peripheral expression of miRNAs, including miR-146a, miR-146b, miR-150, miR-155, miR-125a5p, miR-223, miR-26a, and miR-21, as well as their target mRNAs, was analyzed in 90 RA patients and 30 HCs via quantitative real-time polymerase chain reaction (RT-PCR) assay. We compared differences between the patients in terms of good response (GR; n = 55) and poor response (PR; n = 35) to the conventional therapeutic approach. Results: All miRNAs were significantly overexpressed in RA patients. The expression of miR-155, miR-150, miR-146a, miR-146b, miR-125a-5p, and miR-223 increased in both groups of RA patients, compared to HCs, and miR-26a and miR-21 were the only upregulated miRNAs in the GR group versus HCs. Among the upregulated miRNAs, miR-125a-5p expression significantly changed in GR and PR patients (P = 0.047). The ROC curve analysis indicated the potential involvement of miR-125a-5p in the pathogenesis of RA. We also observed the downregulated expression of GATA3, RORC, FOXP3, TBX21, STAT1, and TRAF6 in RA patients versus HCs. Conclusion: Our findings indicated that different expression levels of miR-125a-5p in the GR and PR groups of patients may serve as a therapeutic response biomarker, which can be also used as a target for therapeutic interventions.