Epigenetic alterations in autoimmune rheumatic diseases.

The potential roles of epigenetic alterations in the pathogenesis of autoimmune rheumatic diseases are raising great expectations among clinicians and researchers. Epigenetic mechanisms regulate gene expression and are sensitive to external stimuli, bridging the gap between environmental and genetic factors. Considerable evidence of epigenetic changes, particularly altered patterns of DNA methylation, exists in diseases such as systemic lupus erythematosus (SLE) and rheumatoid arthritis. The importance of such changes in the pathology of rheumatic diseases has been demonstrated by examining the relationship between gene-specific methylation and SLE in monozygotic twins discordant for the disease, in whom genetic variability is excluded as a cause for discordance. Several studies have highlighted the importance of the tissue-specificity of DNA methylation changes, an aspect which-in contrast with genetic analysis-must be considered when designing epigenetic studies. Here I discuss the proposed mechanisms and implications of DNA methylation changes in the pathogenesis of autoimmune rheumatic diseases, the prospects for future epigenetic studies in rheumatology, the relevance of specific DNA methylation markers and the potential use of drugs with an epigenetic effect in the clinical management of these diseases.