Temporal variability of serum miR-191, miR-223, miR-128, and miR-24 in multiple sclerosis: A 4-year follow-up study

Background: Circulating microRNAs (miRNA) are suggested to be a promising biomarker for multiple sclerosis (MS). Previously, miR-128-3p, miR-24-3p, miR-191-5p and miR-223-3p have been reported to associate with MS pathology. However, their longitudinal changes and association with the disease activity have not been studied. Objectives: To evaluate the serum temporal variability of miR-128-3p, miR-191-5p, miR-24-3p, and miR-223-3p and their association with disability and disease activity in MS. Methods: The expression of four miRNAs in serum was studied in 57 MS patients, 18 clinically isolated syndrome patients, and 32 healthy controls over the four-year follow-up. Results: At the baseline, miR-191-5p was overexpressed in RRMS in comparison to controls, and its levels correlated positively with EDSS and progression index (PI) in RRMS. Increased levels of miR-128-3p were detected in PPMS in comparison to controls, and increased levels correlated with EDSS and PI in RRMS. The expression of miR-24-3p and miR-223-3p did not differ between the subtypes, but miR-223-3p correlated negatively with T1 lesions volumes in SPMS and PPMS. Over the four-years follow-up period, the expression of miR-128-3p and miR-24-3p was stable longitudinally, while temporal changes of miR-191-5p and miR-223-3p were observed in MS. Temporal changes in miR-191-5p were observed to be associated with an increase of EDSS or MRI activity, while the variability of miR-223-3p was associated with relapses. Conclusion: Temporal variability of miR-191-5p and miR-223-3p are associated with changes in disability accumulation and disease activity. While, miR-128-3p was stably expressed and associated with the PPMS subtype and correlated with disability accumulation.