Plasma micro-RNA-22 is associated with disease activity in well-established rheumatoid arthritis

Micro-RNAs (miRNAs) are an endogenous small, single-stranded, non-coding RNAs with a 18-25 nucleotide long and have been reported as potential extracellular biomarkers of various diseases. They mainly decrease the gene expression by inhibiting the translation or cause mRNA destabilisation. The aim of our study was to identify miRNAs whose concentration may be associated with severity of rheumatoid arthritis (RA).

A total of 74 unrelated individuals, 50 with RA and 24 in a control group were enrolled to the study. Real-time PCR was used to evaluate the plasma concentration levels of 8 miRNAs: miR-26a, miR-125b, miR-20b, miR-22, miR-221, miR-17, miR-93, miR-106b.

The logistic regression results showed that miR-22 (p=0.0003) and miR-26a (p=0.049) may be the most important molecules distinguishing RA patients and healthy controls. Moreover, the quantity of miR-22 was different between rheumatoid factor (RF)-positive and RF-negative patients (p=0.04).

In this study we demonstrated for the first time that plasma concentration of miR-22 may be considered as a potential molecular marker associated with disease activity.