A systematic review of the role of DNA methylation on inflammatory genes in ulcerative colitis

Background: Ulcerative colitis (UC) is an idiopathic disease of the large intestine with evidence pointing to the role of epigenetic changes. Methods: Searches were performed in three databases (EMBASE, MEDLINE and Web of Science), following PRISMA protocol. DNA methylation was the only epigenetic mechanism affecting genes linked to inflammatory response in UC. Results: A total of 25 differentially methylated inflammatory genes were identified. Hypermethylation of miR-1247 significantly correlates (p = 0.0006) with refractory UC while PAR2 hypermethylation correlates (p = 0.007) with corticosteroid dependence. Conclusion: Evidence points to a step-wise increase in methylation status of the genome between a healthy colon, quiescent UC and when inflamed. Inflammatory genes (which are aberrantly methylated), have also been implicated in cancer development in UC.