miR-146a and miR-155 expression in PBMCs from patients with Sjögren's syndrome.

Background: An increasing number of studies have revealed that microRNA (miRNA) contributes to the pathogenesis of autoimmune diseases. The objective of this study is to investigate the miR-146a and miR-155 levels in peripheral mononuclear blood cells from patients with primary Sjögren's syndrome (pSS) who were not receiving medications and to examine the correlations between these miRNA levels and the clinical features of the disease.

Method: Using real-time polymerase chain reaction analysis of miRNAs, the miR-146a and miR-155 expression levels were assessed in peripheral mononuclear blood cells from 27 patients with pSS and 22 healthy controls, and the relationships between these miRNA levels and the visual analog scale (VAS) scores for dry mouth, dry eyes, and parotid gland swelling were investigated.

Results: Compared with the healthy controls, the miR-146a expression level was significantly increased in the patients with pSS (P = 0.0182) and was positively correlated with the VAS scores for parotid swelling (r = 0.4475, P = 0.0192) and dry eyes (r = 0.4051, P = 0.0361). Although the miR-155 expression level was significantly decreased in the patients with pSS (P = 0.0131), the miR-155 expression positively correlated with the VAS score for dry eyes (r = 0.4894, P = 0.0096).

Conclusion: Our results demonstrated miR-146a overexpression and miR-155 underexpression in the peripheral mononuclear blood cells of the patients with pSS. Furthermore, the expression levels of these miRNAs correlated with the patients' clinical features. Our data suggest that miR-146a and miR-155 might play important roles in the pathogenesis of pSS and that their expression levels may be useful for diagnosing pSS and for predicting disease activity and therapeutic responses.