Exosomal microRNAs as Early Transition Biomarkers from Recurrent-Remissive to Secondary Progressive Multiple Sclerosis.

Multiple sclerosis (MS) is a chronic, immune-mediated disease that affects young adults, leading to neurological disability. Regardless of the studies and the research involved in developing an efficient disease-modifying therapy (DMT), relapsing-remitting multiple sclerosis (RRMS) will transition to a progressive multiple sclerosis phenotype. The moment of transition from RRMS to secondary progressive multiple sclerosis (SPMS) is difficult to predict, and the diagnosis is based on the accumulation of disabilities in the evolution of the disease. Research on microRNAs' (miRNAs) role in MS began in the early 2000s, with miR-155 frequently cited for its link to blood-brain barrier dysfunction and neurodegeneration, making it an early transition biomarker from RRMS to SPMS. The purpose of this review is to reveal the importance of finding a biomarker from the molecular field that will be able to identify the transition phase so patients can receive high-efficacy treatments and to cease the clinical progression.