Cellular microRNAs (miRNAs) and Sjögren's syndrome: candidate regulators of autoimmune response and autoantigen expression.

MicroRNAs (miRNAs) are small non-coding RNA molecules that suppress gene expression at post-transcriptional level. miRNAs are considered as fine-tuning regulators of diverse biological processes, including the development and function of the immune system. Emerging data have implicated the deregulated expression of certain miRNAs or miRNA networks in the pathogenesis of autoimmune diseases. Sjögren's syndrome (SS) is a common chronic autoimmune disease, characterized by destruction and dysfunction of the exocrine glands (predominantly of the salivary and lachrymal glands). Humoral autoimmune responses observed in the disease, primarily target Ro/SSA and La/SSB ribonucleoproteins, whilst aberrantly increased expression of these autoantigens has been described in the salivary glands (SG) and the salivary gland epithelial cells (SGEC) of SS patients. Comparative array analysis of miRNA expression in the SGs of SS and control subjects had revealed distinctive miRNA signatures in SS patients, associated with glandular inflammation and dysfunction. Furthermore, the expression analysis of miRNAs that are predicted to target Ro/SSA and La/SSB autoantigens revealed differential expression of certain miRNAs in the SG tissues, SGECs and peripheral blood mononuclear cells (PBMC) of SS patients and controls. Although these association data implicate miRNAs in SS pathogenesis, thorough functional studies are needed to delineate their role in disease.