Altered gene expression of miR-155 in peripheral blood mononuclear cells of Multiple sclerosis patients: Correlation with TH17 frequency, inflammatory cytokine profile and autoimmunity

•miR-155 is obviously upregulated in PBMCs of MS patients.•There is a positive correlation between miR-155 expression with increased frequency of Th17 cells in MS patients.•There is a positive correlation between miR-155 expression with increased secreted levels of Th17 related inflammatory cytokines including IL-6, IL-17 and IL-21 in serum of MS patients.•miR-155 can be targeted as a promising therapeutic strategy for the management and prevention of MS occurrence and progression. In the chronic, organ-specific autoimmune disorder known as multiple sclerosis (MS), the myelin sheath is attacked by immune cells, leading to damage to the central nervous system (CNS). It has been discovered that miRNAs are important in the etiology of MS, since deregulation of miRNAs can lead to defects in immune tolerance. In this study, we sought to investigate the involvement of miR-155 in MS disorder through examination of its altered expression in peripheral blood mononuclear cells (PBMCs) of patients with MS in compare with healthy controls. Furthermore, we investigated the frequency of T helper 17 cells (Th17) in MS patients and analyzed not only the expression of inflammatory cytokines including IL-6, IL-17 and IL-21 in patients’ PBMCs, but also their secreted levels in serum of patients suffering from MS. Subsequently, we assessed the correlation between miR-155 expression with Th17 frequency and levels of released cytokines in serum. Upregulated expression of miR-155 was detected in PBMCs of MS patients and the positive correlation between its expression with increased frequency of Th17 cells and their related inflammatory cytokine profile augmented secretion in serum were identified. In conclusion, our study revealed the significant association between Th17 frequency, increased level of cytokines related to Th17 differentiation and function with miR-155 augmented expression in PBMCs. So, our findings suggested that miR-155 and especially its expression in immune cells including effector T cells can be the target of future therapeutic strategies for the management and prevention of MS progression, however, further research is requisite before this approach can be utilized in clinical practice. [Display omitted] Created with biorender.com