LAUSR

Background Micro-ribonucleic acids (microRNAs) comprise a class of small non-coding RNAs that regulate gene expression on post transcriptional level. Levels of miR-124 have been found to be decreased in rheumatoid arthritis (RA) synoviocytes and in vivo studies have shown that treatment with pre-miR-124 suppresses the progression of joint damage1. Objectives To evaluate the expression levels of miR-124–3 p in plasma of RA patients and to determine its possible role as biomarker for diagnosis and disease activity. Methods 34 RA patients according to the 1987 ACR criteria were included in the study. Expression levels of miR-124–3 p in the plasma were determined by PCR (SYBR Green technology). 2-ΔΔCt method was used for analysis. 10 healthy donors were used as controls. Results Expression levels of miR-124–3 p were upregulated in the plasma of 33 (97.06%) of the patients when compared to controls. Receiver operating characteristic curve analysis was conducted in order to evaluate the diagnostic accuracy of the expression levels of the studied miRNA in the plasma. Area under the curve for miR-124–3 p was 0.879 (95% CI=0.740–1.00), p=0.303 × 10–3. When the relative quantification (RQ) cut value was 2.89, the sensitivity was 91.2% and the specificity was 80%. Levels of miR-124–3 p in plasma correlated with the diagnosis (p=0.106 × 10–3), with markers of inflammation – ESR (p=0.0497) and CRP (p=0.047) as well as with the immunological activity – the presence of RF (p=0.007), RF IgM (p=0.004), RF IgG (p=0.004), RF IgA (p=0.005) and anti-CCP antibodies in the serum (p=0.025). Conclusions In contrary to the literature data that report levels of miR-124 to be decreased in RA synovial fibroblasts we found increased expression of miR-124–3 p in the plasma of RA patients which might reflect the pathophysiological response to the inflammation, the effect of the treatment regimen or the presence of miR-124a gene promotor hypermethylation in the synovial tissue which might downregulate miR-124 locally.1 2 To our knowledge this is the first study to evaluate the diagnostic accuracy of plasma levels of miR-124 in RA patients as well as the possibility of using miR-124 as biomarker for disease activity but larger set is needed to confirm these results in the clinical practice. References [1] Nakamachi Y, et al. MicroRNA-124a is a key regulator of proliferation and monocyte chemoattractant protein 1 secretion in fibroblast-like synoviocytes from patients with rheumatoid arthritis, Arthritis Rheum2009;60(5):1294–1304. [2] Zhou Q, et al. Research of the Methylation Status of miR-124a Gene Promoter among Rheumatoid Arthritis Patients. Clin Dev Immunol2013(2013):524204. Acknowledgements The study was supported by Grant 76/2016 funded by Medical University – Sofia, Bulgaria. Disclosure of Interest None declared