Epigenetics and Autoimmune Thyroid Diseases.

Fabio Coppedè

doi:10.3389/fendo.2017.00149

Abstract

Increasing evidence suggests that epigenetic modifications, including changes in DNA methylation, covalent modifications of histone tails, and gene silencing mediated by non-coding RNA molecules, play a substantial role in the pathogenesis of autoimmune disorders and might be seen as the result of environmental insults that trigger these conditions. Studies in cells and tissues of patients with autoimmune thyroid diseases (AITD), and particularly in Graves’ disease (GD) and Hashimoto’s thyroiditis (HT), are increasingly revealing altered epigenetic marks and resultant deregulation of gene expression levels, but the available data are still limited to be translated into the clinical settings. Particularly, genome-wide methylation and histone tail modification screenings are limited to a few studies in GD patients, and the diagnostic values of the observed epigenetic changes or their potential prognostic utility are still unclear. Similarly, data concerning microRNA expression in AITD patients are largely descriptive and not yet translated into the clinics. In addition, studies relating certain environmental exposures to specific epigenetic changes in AITD and studies evaluating the crosstalk between different epigenetic mechanisms are largely missing. In summary, despite that there is a clear evidence of epigenetic impairment in AITD, further research is required for a better understanding of the epigenetic networks involved in disease pathogenesis, thereby opening the way for potential diagnostic and prognostic tools, as well as for epigenetic interventions in the patients.

Highlights

Epigenetics is an umbrella term referred to heritable and reversible marks, such as DNA methylation or covalent modifications of histone tails, that regulate the chromatin structure and switch genes “on” and “off ” without changing the primary DNA sequence [1]
Autoimmune thyroid disease patients can be clinically categorized into those with hyperthyroidism (GD), those with hypothyroidism (HT), and euthyroid subjects harboring thyroid autoantibodies [7]. Despite their phenotypic differences, it is believed that autoimmune thyroid diseases (AITD) patients share some common etiological factors [7], and genetic studies have revealed that if certain genes are unique for Graves’ disease (GD) or Hashimoto’s thyroiditis (HT), others are common to both disorders or to AITD and other autoimmune diseases [10]
Different AITD phenotypes are often seen in members of the same family [7], and a significant increase in the prevalence of certain other autoimmune disorders has been reported in AITD patients [9]

Summary

Introduction

Epigenetics is an umbrella term referred to heritable and reversible marks, such as DNA methylation or covalent modifications of histone tails, that regulate the chromatin structure and switch genes “on” and “off ” without changing the primary DNA sequence [1]. Recent studies have clearly demonstrated a significant increased risk of other autoimmune diseases in patients with AITD and there is evidence of genetic factors that influence the association of different autoimmune disorders [9].

Results

Conclusion