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AB0017 COMPARISON BETWEEN THE ALTERED PERIPHERAL BLOOD MIRNA EXPRESSION IN PATIENTS WITH RHEUMATOID ARTHRITIS AND SYSTEMIC LUPUS ERYTEMATOSUS

Background: MicroRNAs (miRNAs) are a class of small, non-coding RNAs that negatively regulate gene expression at posttranscriptional level. Altered miRNA expression in the circulation has been described in inflammatory joint diseases such as rheumatoid arthritis (RA) as well as in systemic rheumatic diseases, such as systemic lupus erythematosus (SLE). miR-146a and miR-155 have been found to regulate key signaling pathways involved in the pathogenesis of RA and SLE [1-2]. Objectives: To compare the expression levels of miR-146a and miR-155 in peripheral blood (PB) from RA and SLE patients in regard to their use as disease biomarkers. Methods: 63 RA patients and 40 SLE were included in the study. The expression levels of miR-146a and miR-155 in whole PB were determined by qPCR (SybrGreen technology) and compared to healthy controls (HCs). Relative changes of gene expression levels of the studied miRNAs were calculated by 2-ΔΔCt method. SPSS was used for statistical analysis. Results: 29 (46.03%) of the RA patients showed overexpression of miR-146a in the PB when compared to HCs, but the levels were not statistically significant to differentiate patients from HCs (p=0.365). 34 (53.97%) of the RA patients didn’t show a statistically significant expression of miR-155 in the PB when compared to HCs and PB expression of miR-155 couldn’t be used for differentiating RA from HCs (p=0.074). In the group of SLE patients the PB levels of miR-146a were overexpressed in 25 (62.5%) and levels of miR-155 were increased in 20 (50.0%) of the patients (p<0.05). Conclusion: Although miR-146a and miR-155 are involved in key signaling pathways in the pathogenesis of RA their whole PB expression could not fully reflect the local pathological process and thus to differentiate patients from HCs. The expression of both miRNAs in whole PB of SLE samples showed a possibility for discriminating patients from HCs. Further analysis with larger sets is needed to confirm if altered systemic miRNA expression levels could be used in the clinical practice as disease biomarkers. References [1] Honarpisheh M, Köhler P, von Rauchhaupt E, Lech M. The Involvement of MicroRNAs in Modulation of Innate and Adaptive Immunity in Systemic Lupus Erythematosus and Lupus Nephritis. J Immunol Res. 2018; 2018:4126106. [2] Zhou Q, Haupt S, Kreuzer JT, et al. Decreased expression of miR-146a and miR-155 contributes to an abnormal Treg phenotype in patients with rheumatoid arthritis. Anna Rheum Dis. 2015; 74:1265-1274. Acknowledgement: The study was supported by Grant 60/2013 and Grant 51/2014 and funded by Medical University-Sofia. Disclosure of Interests: None declared