Upregulated miR-146a Expression in Peripheral Blood Relates to Th17 and Treg Imbalance in Elder Rheumatoid Arthritis Patients

Background: The expression level of microRNA-146a (miR-146a) increased in peripheral blood and synovialis tissue of rheumatoid arthritis (RA) patient, and it may play an important role in the pathological process of RA. We investigated its possibility as a diagnostic marker and the correlation with T helper 17 (Th17) and Treg cells in elder RA patients. Methods: Blood samples were collected from 38 active RA patients, 38 inactive RA patients, and 40 healthy controls. RNA expression levels of miR-146a were detected from the peripheral blood samples. The proportion of Th17 and Treg cells were analyzed, as well as their cell-specific transcription factor retinoic acid-related orphan receptor variant 2 (RORc) and forkhead box protein 3 (FOXP3). Furthermore, secretion of pre-inflammatory and anti-inflammatory factors was detected. Correlations between miR-146a and these factors were also analyzed. Results: Compared with healthy control, expression levels of miR-146a in inactive and active groups were significantly higher, with the highest level in active group. The expression of miR-146a and the RA severity, Th17 cell ratio, RORc expression, IL-17 level showed a significant positive correlation, while it showed a significantly negative correlation with Treg cell ration, FOXP3 expression, and TGF-β1 secretion. Conclusions: These results suggested that miR-146a may be used as a disease progression marker in the peripheral blood of elder RA patients.