Epigenetic process involved in multiple sclerosis pathophysiology with emphasis in miRNAs function

Abstract

Multiple sclerosis (MS) is a neurodegenerative autoimmune disease of the central nervous system (CNS). The pathophysiology is characterized by intense inflammatory activity and involvement of immune cells (CD4 +, CD8 + and B cells); glial cells and disrupted permeability of the blood brain barrier (BBB). Currently, its etiology remains unknown; it is believed that environmental factors and genetic predisposition are responsible for the autoimmunity. Discrepancies in genetic inheritance patterns of disease, prevalence of gender and low concordance rate between homozygous twins suggest participation of epigenetic processes in multiple sclerosis. Epigenetic processes are responsible for gene expression without causing changes in the genetic code and are highly sensitive to environmental variations. In addition, they are preserved between cell division and interfere in different biological processes; however they can be reversed. The three most studied processes are DNA methylation, histone acetylation and gene silencing by miRNAs. miRNAs are specifically being studied since they regulate one third of gene expression in mammals. These small RNA segments of approximately 22 nucleotides have elucidated several aspects of MS and seem to interact and regulate immune system and CNS; they may become valuable biomarkers for that disease.