Association between miRNA-145 and miRNA-155 expression in peripheral blood mononuclear cells of patients with multiple sclerosis: a case-control study.

Introduction: MicroRNAs (miR or miRNA) are short regulatory RNAs, which modulate post-transcriptional gene expression. Dysregulation of these molecules contributes to pathogenicity of autoimmune disorders, such as multiple sclerosis (MS).

Aims: This study was conducted to investigate changed expression pattern of miRNA-145 and miRNA-155 in MS.

Methods: We collected blood samples of 75 patients with relapsing-remitting MS patients and 75 healthy controls. Ficoll-Hypaque density gradient method was used to isolate peripheral blood mononuclear cells. Also, total RNA was extracted and subjected to RT-PCR analysis. We used the Mann-Whitney U test to evaluate the differences in expression levels of target miRNAs between the groups.

Results: We found that expression of miRNA-145 (P = 0.012) and miRNA-155 (P = 0.005) were partly reduced in patients with relapse-remitting MS in comparison with healthy controls. The miRNA-145 had an area under curve (AUC) of 0.621 (P = 0.01) and miRNA-155 levels had an AUC of 0.625 (P = 0.008).

Conclusion: Decreased expression of miRNA-145 and miRNA-155 contributes to development of relapse-remitting MS, while further large scale observational studies and meta-analyses are required.