MicroRNA-146a expression as a potential biomarker for rheumatoid arthritis in Egypt

MicroRNAs (miRNAs) are small non-coding RNAs, whose role in regulating diverse immune functions, suggests they might play a role as biomarkers for immune mediated disorders. Studies showed that miRNA-146a (miR-146a) expression is increased by proinflammatory cytokines and is an important modulator of differentiation and function of cells of innate and adaptive immunity. The current study aimed to evaluate the expression of miR-146a as a potential biomarker for diagnosis of rheumatoid arthritis (RA) and to explore its association with disease activity. The study enrolled 50 Egyptian subjects divided into a patient group, which comprised 25 RA patients, and a control group which comprised 25 healthy individuals. The disease activity for the patients' group was determined by simplified disease activity index. Relative quantification of miR-146a expression in whole blood was determined using reverse transcriptase quantitative real time polymerase chain reaction. There were highly significant statistical differences between patients and healthy controls as regards miR-146a relative expression, erythrocyte sedimentation rate (ESR) and anti-cyclic citrullinated peptide (anti-CCP) (p < 0.001). Highly significant statistical differences (p < 0.001) were also found between different patients' subgroups as regards miR-146a relative expression and ESR. miR-146a levels correlated positively with those of ESR, C-reactive protein and anti-CCP (p < 0.001). miR-146a illustrated best performance in diagnosing RA, showing the highest sensitivity and specificity (96% and 100%, respectively) (AUC: 0.992 at a cut off value of ⩾2.16) compared to anti-CCP (sensitivity: 68%, specificity: 100% and AUC: 0.87 at a cut off value of ⩾ 22 U/ml) and RF (sensitivity: 56%, specificity: 80% and AUC: 0.992 at a cut off value of ⩾13 U/ml). This study demonstrated that miR-146a expression was highly significantly elevated in whole blood of patients with RA. Its diagnostic performance was better than anti-CCP and RF and its level of expression correlates with disease activity.