BACKGROUND: Recent studies identified a set of differentially expressed miRNAs in whole blood that may discriminate neuromyelitis optica spectrum disorders (NMOSD) from relapsing-remitting multiple sclerosis (RRMS). This study invalidated 9 known miRNAs in Chinese patients.

MATERIAL AND METHODS: The levels of miRNAs in whole blood were assayed in healthy controls (n=20) and patients with NMOSD (n=45), RRMS (n=17) by quantitative real-time polymerase chain reaction (qRT-PCR), and pairwise-compared between groups. They were further analyzed for association with clinical features and MRI findings of the diseases.

RESULTS: Compared with healthy controls, miR-22b-5p, miR-30b-5p and miR-126-5p were down-regulated in NMOSD, in contrast, both miR-101-5p and miR-126-5p were up-regulated in RRMS. Moreover, the levels of miR-101-5p, miR-126-5p and miR-660-5p, were significantly higher in RRMS than in NMOSD (P=0.04, 0.01 and 0.02, respectively). The level of miR-576-5p was significantly higher in patients underwent relapse for ≤3 times than those for ≥4 times. In addition, its level was significantly higher in patients suffered from a severe visual impairment (visual sight ≤0.1). Moreover, the levels of each of the 9 miRNAs were lower in NMOSD patients with intracranial lesions (NMOSD-IC) than those without (NMOSD-non-IC). Despite correlations of miRNAs with these disease subtypes, all AUCs of ROC generated to discriminate patients and controls, as well as intracranial lesions, were <0.8.

CONCLUSIONS: Certain miRNAs are associated with RRMS and NMOSD. They are also related to the clinical features, especially intracranial lesions of NMOSD. However, none of the miRNAs alone or in combination was powerful to ensure the diagnosis and differentiation of the 2 disease subtypes.

Keywords: Multiple Sclerosis, Neuromyelitis Optica