Epigenetics in multiple sclerosis

Abstract

The development of multiple sclerosis (MS) is based on complex interactions between genetic and environmental factors. Epigenetic regulation is a biological phenomenon defined as the modification of gene expression without alteration of the DNA sequence, and is currently thought to underlie the interactions between the genetic and environmental risks of MS. The molecular mechanisms of epigenetics include DNA methylation, histone modification, and microRNAs. Observational data obtained from epidemiological studies of MS, such as the parent-of-origin effect and the longitudinal increase in female patients, suggest that epigenetic mechanisms are involved in MS development, although the molecular basis remains unclear. Interestingly, environmental factors related to the development of MS, such as Epstein-Barr virus, smoking, and Vitamin D, have been shown to regulate gene expression through epigenetic mechanisms in some experimental settings. One study showed no reproducible differences among DNA methylation profiles in peripheral blood CD4+ T cells between three monozygotic twin pairs discordant for MS. However, several studies have shown that dysregulated DNA methylation of genes is related to abnormal immune reactions and post-translational modifications of myelin proteins in MS brain samples. In addition, abnormal microRNA profiles have been reported in brain tissues and peripheral blood immune cells obtained from MS patients. In this article, we will review the studies on the epigenetics of MS and discuss the perspectives for future research.