Background: Circulating microRNAs have emerged as novel multiple sclerosis (MS) biomarkers.

Objective: To assess the association between candidate miR expression in serum samples of patients with MS and the disease course.

Methods: Serum levels of ten microRNAs (ie, miR-199, miR-128-3p, miR-20a-5p, miR-27a-3p, miR-15b-5p, miR-325, miR-92a1-5p, miR-223-5p, miR-22-5p, and miR-23a-5p) were measured in 74 MS cases and 17 non-MS controls consecutively enrolled at Verona University Hospital. The association of microRNA expression with patients' clinical and MRI features was analyzed. Candidate microRNAs were detected by real-time PCR and expressed as ratio of each microRNA level to a normalizer.

Results: Serum miR-128-3p levels were higher in progressive than relapsing MS (median ratio 2.86 vs 0.73, P = .036). In addition, miR-128-3p was upregulated in patients without relapses after sample collection compared to cases who relapsed (1.64 vs 0.82; P = .014). miR-128-3p levels and relapse rate were inversely correlated (r = -.44, P = .008).

Conclusions: Serum levels of mir-128-3p could be related to biological mechanisms underlying MS activity and progression.