Evaluation of Selected MicroRNAs Expression in Remission Phase of Multiple Sclerosis and Their Potential Link to Cognition, Depression, and Disability.

Accumulating data suggests that miRNAs might play a major role in neuroinflammatory processes. Therefore, our study aimed to first estimate the levels of miR-155, miR-326, and miR-301a in serum of RR-MS patients in the remission phase and then compare the levels of the examined miRNAs at different times after relapse. In this study, 36 RR-MS patients in the remission phase took part. We analyzed two subgroups of RR-MS: one, 1 to 2 months after completing steroid treatment during relapse (post-acute; n = 13) and the other, over 2 years without any relapse (stable; n = 23). Moreover, we made correlations between these biochemical results and clinical parameters of cognitive impairment, depression, and disability. The obtained results presented downregulation of miR-155 and miR-301a (in 94% and 51% samples, respectively) and overexpression of miR-326 (in 72% samples) in RR-MS patients. Moreover, we observed a positive correlation between the relative expression of miRNAs and BDI (Beck Depression Index) for miR-326 (rho = 0.385459, p = 0.022210; Spearman's rank correlation) and miR-301a (rho = 0.435131, p = 0.008991; Spearman rank correlation). We also observed the differences in expression levels between the post-acute and stable phases of RR-MS. The expression levels of miR-301a and miR155 were higher in the post-acute vs. stable phase of remission (2.385 vs. 0.524 and 0.594 vs. 0.147; respectively). Our study, for the first time, presents miRNA expression differences in two stages of remission: post-acute and stable.