Differential expression of microRNAs in peripheral blood mononuclear cells of multiple sclerosis patients

MicroRNAs (miRNAs) are a class of short single-stranded RNAs that act as post-transcriptional regulators of gene expression and represent a major group of regulators potentially associated with human multifactorial diseases. Multiple sclerosis (MS) is a complex autoimmune disease of the central nervous system characterized by chronic inflammation, demyelination, and axonal damage. As miRNA-dependent alterations in gene expression in hematopoietic cells are critical for mounting an appropriate immune response, their deregulation may result in defects in immune tolerance. In this frame, we sought to explore the possible involvement of miRNAs in MS pathogenesis by monitoring the differential expression of 22 miRNAs (expressed in the immune system or transcribed from previously reported MS susceptibility loci) in peripheral blood mononuclear cells of MS patients and healthy controls by using a microbead-based technology. Four miRNAs resulted >3 folds up-regulated in MS vs controls, whereas only 1 resulted down-regulated. Interestingly, 2 of the most up-regulated miRNAs (mir-155, mir-146a) have been reported to be altered also in rheumatoid arthritis and systemic lupus erythematosus, suggesting shared pathogenic mechanisms with MS. To confirm mir-155 and mir-146a up-regulation, qPCR experiments will be performed. Moreover, the role of these miRNAs in MS susceptibility will be investigated by genotyping single nucleotide polymorphisms mapping in mir-155 and mir-146a regions.