Identification of circulating miR-22-3p and let-7a-5p as novel diagnostic biomarkers for rheumatoid arthritis.

Objectives: Early and correct diagnosis would be beneficial for outcomes of rheumatoid arthritis (RA), but there are some limitations in current diagnostic tools. In this study, we aimed to evaluate the diagnostic value of circulating miR-22-3p and let-7a-5p in RA.

Methods: Seventy-six RA patients, 30 systemic lupus erythematosus patients, 32 Sjögren's syndrome patients and 36 healthy donors recruited at the First Affiliated Hospital of Fujian Medical University (China) were included in this study. Circulating miR-22-3p and let-7a-5p in plasma were measured using reverse transcriptase quantitative PCR and serum cytokines were detected by cytometric bead array. The participants' clinical materials were also collected. Receiver operating characteristic curve analysis and correlation analysis were performed to assess the potential value of circulating miRNAs in RA.

Results: Circulating miR-22-3p and let-7a-5p are significantly increased in RA patients and able to distinguish RA patients from other populations. Circulating let-7a-5p has been shown to improve the diagnostic ability of current laboratory indicators anti-cyclic citrullinated peptide antibodies and rheumatoid factor. Moreover, the discriminatory capacity of both circulating miRNAs contribute to complement the diagnosis for seronegative RA. Meanwhile, correlation analysis reveals that circulating miR-22-3p positively correlates with haemoglobin, serum bilirubin, albumin and IL-17 but negatively correlates with mean platelet volume as well as let-7a-5p.

Conclusions: The increased circulating miR-22-3p and let-7a-5p levels in RA patients, especially in seronegative RA patients, may provide potential promising diagnostic biomarkers for RA in clinical practice.