MicroRNAs (miRNAs) regulate the expression of many genes and may be involved in regulating the immune response. Expression of microRNA 146a (miRNA 146a) in peripheral blood mononuclear cells was studied by real-time polymerase chain reaction in 70 patients with rheumatoid arthritis (RA), 45 patients with knee osteoarthritis (OA), and 60 healthy controls. Disease activity of RA was assessed using disease activity score (DAS) 28 and physical disability using the Improved Health Assessment Questionnaire.
miRNA 146a expression was significantly higher in patients with RA than in those with OA and in controls (p<0.0001) but did not differ between the latter two groups (p=0.06). Tumor necrosis factor-alpha (TNF-α) was significantly higher in RA than in OA and controls (p<0.0001) and in OA than controls (p=0.001). In patients with RA, miRNA 146a positively correlated with TNF-α (p=0.0003), erythrocyte sedimentation rate (ESR) (p=0.022), and DAS 28 (p=0.009). miRNA 146a expression did not differ between patients with RA receiving anti TNF-α and those receiving conventional therapy (p>0.05).
miRNA 146a expression is upregulated in patients with RA and may be a potentially useful marker of disease activity in these patients. Lack of overexpression of miRNA 146a in the presence of increased TNF-α in OA requires further investigation.