Background MicroRNAs (miRNAs) are small noncoding RNA molecules that negatively regulate gene expression via degradation or translational repression of their targeted mRNAs. It is known that miRNAs are present in human plasma in a stable form and they can be potential non-invasive biomarkers for early detection of cancers or some other diseases. Recent reports showed that the expression of miR-146a, miR-155, miR-132, miR-16 inRA peripheral blood mononuclear cells (PBMC) was higher than healthy control.

Objectives In this study, the expression of miR-155 and miR-146a is determined in PBMC and plasma from rheumatoid arthritis (RA) patients.

Methods PBMC and plasma were separated from peripheral blood of 34 RA patients and 15 healthy individuals. Total RNAs were isolated and miRNAs were purified. The levels of miR-155 and miR-146a were determined by quantitative reverse transcription PCR (qRT-PCR). U6 was used as housekeeping control. The amount of target miRNA was normalized relative to the amount of U6 (ΔCt =ΔCt_miRNA-ΔCt_U6). Relative expression levels were expressed as 2^{-Δ Ct}. The 2-sample t-test was used for all 2 sample comparisons (SPSS, version 13.0). P<0.05 was considered significant.

Results The expression of PBMC and plasma miR-155 was higher in the RA patients than that in the healthy control individuals (0.08±0.08 vs 0.05±0.03, P<0.05; 5.90±6.70 vs 1.27±2.00, P<0.05). The expression of miR-146a in PBMC and plasma in RA patients and controls is 1.33±1.19 vs 0.79±0.55 (P<0.05)and 741.43±1000.64 vs 299.81±294.92 (P>0.05). According to their DAS28 value, RA patients were divided into high activity group (23 cases, DAS28≥5.0) and low activity group (11 cases, DAS28<5.0). The plasma miR-155 and miR-146a expression was significantly higher in high activity group than that in low activity group. There was no significantly difference in the expression of PBMC miR-155 and miR-146a between the two groups.

Conclusions The expression of PBMC and plasma miR-155 and miR-146a is higher in RA patients. The expression of plasma miR-155 and miR-146a is associated with RA patients’ activity. Plasma miR-155 and miR-146a may be potential non-invasive biomarkers for RA diagnosis and RA activity assessment.

Disclosure of Interest None Declared