MicroRNA-150 and microRNA-155 as Molecular Biomarkers in Multiple Sclerosis

Multiple sclerosis (MS) is a chronic neurodegenerative autoimmune disease characterized by infiltration of immune cells into the central nervous system (CNS) with subsequent demyelination, axonal degeneration and neuronal death MS is the most common cause of non traumatic lifelong disability in young adults, affecting women almost three times as often as men

The incidence of MS is increasing worldwide, together with the socioeconomic impact of the disease There is no definite measure or laboratory marker for the diagnosis of MS yet In a patient presenting with an attack, the most important paraclinical test is magnetic resonance imaging (MRI) with intravenous (iv) contrast agent containing gadolinium. This can both present the nature of the lesions (inflammatory and demyelinating characteristics) for differential diagnosis, and the distribution of the lesions within the CNS (evidence of dissemination in time [DIT] and space [DIS] according to the latest McDonald Criteria (2017) Clinical and imaging findings that may be seen in MS, can also be mimicked by some infectious, neoplastic, genetic, metabolic, vascular and other idiopathic inflammatory demyelinating disorders (IIDD) Therefore, to identify MS-related attacks and determine the final diagnosis is vital for the correct treatment choice and longterm disability prevention.

The currently used biomarkers for diagnosing of MS include IgM and IgG antibodies , chemokines, glycoproteins and cell surface markers of inflammation . However, the disease course is very diverse and the heterogenesity in its phenotype not well correlated with biomarkers currently used thus, it is compulsory to identify new specific biomarkers that can help in distinguishing the different MS phenotypes , anticipate the progress of the disease and afford a correlate with the disability status

So, why are biomarkers for MS still arousing interest? Emerging biomarkers, such as circulating miRNAs, display several advantageous features in comparison with previous methods , The possibility to support the results of the clinical diagnosis distinguishing MS subtypes (PPMS, RRMS, etc.) and quantify MS severity , the fact that collecting blood miRNAs and measuring their expression is easy, poorly invasive, and cheap , the robustness of circulating miRNAs which are highly stable, and the accuracy using composite biomarkers rather than a single one.

MicroRNAs (miRNAs) are small non-coding RNA molecule (containing about 22 nucleotides) found in plants, animals and some viruses, that functions in RNA silencing and post-transcriptional regulation of gene expression.