Tiny RNA Molecule a Potential Diagnostic Biomarker for Ankylosing Spondylitis, Study Says

Levels of a tiny RNA molecule, called miR-214, correlate with ankylosing spondylitis disease activity and may be used as a noninvasive biomarker in diagnosing the disease, a study has found.

The study, “Serum miR‐214 as a novel biomarker for ankylosing spondylitis,” was published in the International Journal of Rheumatic Diseases.

Ankylosing spondylitis (AS) is a type of chronic inflammatory rheumatic disease that mainly affects the joints of the spine, causing chronic pain and lifelong physical disability.

Previous studies have found that microRNAs (miRs; tiny RNA molecules that control the expression of multiple genes) seem to be associated with AS development. More recently, a series of miRs found in patients’ serum (e.g., miR-34a, miR-32, or miR-16) have been suggested as AS biomarkers. However, these studies lacked proper controls for direct comparisons.

In this study, a team of Korean researchers analyzed the potential of serum miRs as diagnostic biomarkers for AS.

Researchers isolated RNA from serum samples of 65 AS patients, 25 rheumatoid arthritis (RA) patients, and 39 healthy individuals used as controls. Each RNA sample was then used as a source for the identification of circulating miRs. Candidate miRs were then validated by quantitative real-time polymerase chain reaction (qPCR) — a technique to measure the expression levels of genes, in this case, of each candidate miR.

Gene expression is the process by which information in a gene is synthesized to create a working product, such as a protein.

In total, 887 miRs were found in serum samples from all three patient groups. From these, the levels of miR-214 were consistently lower in serum samples from AS patients than in RA patients or controls. These findings were then confirmed by qPCR.

Further correlation analysis showed the levels of miR-214 were linked to AS disease activity, measured by the AS Disease Activity Score-C‐reactive protein, and to the amount of white blood cells and platelets present in patients’ serum.

No significant correlations were found between the levels of miR-214 and patients’ age, gender, disease duration, smoking, and use of non‐steroidal anti‐inflammatory drugs or tumor necrosis factor inhibitors.

Moreover, no significant associations were found between the levels of miR-214 and other medical conditions, including peripheral arthritis, enthesitis (inflammation of the tendons, the ligaments that connect muscles to bones), dacylitis (inflammation of fingers/toes), psoriasis, and inflammatory bowel disease.

“miRs are particularly attractive as biomarkers because they are relatively stable. In addition, they can be easily detected in serum or plasma from a single tube of blood, allowing repeated sampling for minimally invasive disease monitoring,” the researchers wrote.

“Results of this study suggest that the expression of serum miR-214 may serve as a new biomarker for the diagnosis of AS. Because of the sample size and clinical heterogeneity of AS, these data should be confirmed by larger studies,” they concluded.