Expression patterns of ciRS-7 and miR-7 in peripheral blood mononuclear cells of rheumatoid arthritis patients

Background: Non-coding RNAs (ncRNAs), including miR-7 and ciRS-7, are implicated in many autoimmune diseases, but their roles in rheumatoid arthritis (RA) stay largely unexplored. Aim of the work: To assess miR-7 and ciRS-7 as diagnostic biomarkers for RA by comparing their expression patterns in patients vs. controls and correlating their profiles with anti-cyclic citrullinated peptide (anti-CCP) levels and clinical findings. Patients and methods: Forty-five patients and 45 controls were enrolled. Enzyme-linked immunosorbent assay (ELISA) was performed to assess plasma anti-CCP levels, and reverse transcription polymerase chain reaction (RT-PCR) was conducted to determine miR-7 and ciRS-7 expression levels. Results: All cases were female with a mean age of 39.6 ± 10.2 years. Cases exhibited significantly lower levels of miR-7 expression than control (median, 0.51 vs. 1.03; p < 0.001), while a significant elevation in ciRS-7 was observed in cases (median, 4.29 vs. 0.93; p < 0.001). Neither miR-7 nor ciRS-7 showed a significant correlation with anti-CCP levels. Meanwhile, miR-7 and ciRS-7 levels significantly correlated with the duration of RA (r_s = 0.32, p = 0.03; r_s = 0.4, p = 0.01, respectively), while the anti-CCP levels demonstrated a significant negative correlation with disease duration (r_s= −0.33, p = 0.03). miR-7 and ciRS-7 significantly distinguish cases from controls at cut-off values of < 0.81 and > 1.7, respectively (AUC = 0.98 and 0.99; p < 0.001), and their combination achieved 100 % diagnostic accuracy, with an AUC of 1 (p < 0.001). Conclusions: miR-7 and ciRS-7 have an inverse relationship, suggesting that ciRS-7 could modulate miR-7 regulatory functions. Both miR-7 and ciRS-7 could be used as diagnostic biomarkers for RA, and their combination could improve RA prediction.