Circulating microRNAs as biomarkers in progressive multiple sclerosis

Background: In multiple sclerosis (MS), microRNA (miRNA) dysregulation is mostly reported in different immune cells, but less information is available on circulating miRNAs that exert strong biomarker potential due to their exceptional stability in body fluids. Objective: The aim of this study was to profile expression of circulating miRNAs in primary progressive multiple sclerosis (PPMS) and secondary progressive multiple sclerosis (SPMS) and assess their association with neurological worsening. Methods: The expressions of 84 different miRNAs were profiled in serum of 83 subjects (62 MS and 21 controls) using miScript miRNA techniques. First, they were screened on 18 PPMS and 10 controls; thereafter, 10 most aberrantly expressed miRNAs were validated on a larger cohort. Results: In comparison with controls, upregulation of miR-191-5p was found in both progressive MS subtypes, while miR-376c-3p was overexpressed only in PPMS. Additionally, upregulation of miR-128-3p and miR-24-3p was detected in PPMS when compared to controls and SPMS. Progression index correlated with miR-128-3p in PPMS and miR-375 in SPMS. Conclusion: We detected overexpression of four miRNAs that have not been previously associated with progressive forms of MS. The increased expression of circulating miR-191-5p seems to be associated with progressive forms of MS, while miR-128-3p seems to be associated mostly with PPMS.