MicroRNAs in rheumatoid arthritis: Altered expression and diagnostic potential

• MicroRNAs are reported to contribute to rheumatoid arthritis pathogenesis.
• During natural course of rheumatoid arthritis microRNAs are primarily overexpressed.
• MicroRNAs 16, 146a/b, 150, 155, and 223 are systemically up-regulated.
• Circulating microRNAs are promising biomarkers in rheumatoid arthritis.
• Serum microRNAs 24 and 125a-5p are diagnostic for RA even in ACPA-negative patients.

Rheumatoid arthritis (RA) is a polygenic disease characterized by autoimmunity and systemic inflammation with progressive impairment of joints that results in lifelong disability and increased mortality. Early diagnosis and therapeutic intervention or treatment can prevent severe disease manifestations in patients suffering from RA. The use of appropriate predictive biomarkers may improve the efficiency of RA therapy. The general aim of this review is to highlight the most recent findings on miRNAs expression profiles in RA patients and to discuss their potential as new biomarkers for diagnostic purposes. The current literature demonstrates that a variety of miRNAs is frequently dysregulated in RA patients. To date, the majority of miRNAs have been found to be overexpressed during the natural course of RA. MiR-16, miR-146a/b, miR-150, miR-155, and miR-223 described here were shown to be overexpressed at the systemic level: in both the periphery and RA joints. Circulating peripheral blood miRNAs, especially miR-16, miR-21, miR-24, miR-26a, miR-125a-5p, miR-125b, miR-126-3p, miR-223, and miR-451, which are elevated in the plasma or serum, are considered to be the most promising non-invasive biomarkers for the detection of RA.