P828 DNA methylation profile defines epigenetic characteristics and molecular targets of Crohn’s disease

Abstract

Abstract Background Inflammatory bowel disease(IBD) is known to be caused by a genetic predisposition involving multiple genes; however, there is growing evidence that abnormal interaction with environmental, particularly epigenetic, factors can have a significant contribution during the development of IBD. Although many studies, particularly genome-wide association studies (GWAS), have been performed to identify the genetic changes underlying the pathogenesis of Crohn’s disease (CD), the role of epigenetic changes in the development of complications arising from CD is poorly understood. Methods Here, we employed an unbiased approach to define DNA methylation alteration in CD patients using the Human Methylation 450K Bead Chip platform. Compared to normal controls, the majority of differential DNA methylation in CD patient samples was in the promoter, intergenic, and gene body regions. Results The DNA methylation profile in CD revealed 134 probes (23 hypermethylated and 111 hypomethylated probes) that were differentially methylated. We validated the methylation levels of 19 genes that showed hypermethylation in CD patients compared with normal control. Technical validation was performed using quantitative MSP analysis and we finally identified that the Fragile Histidine Triad (FHIT) genes were hypermethylated in a disease-specific manner. Using a large cohort for CD patients samples (n = 207), we found that FHIT is frequently methylated in CD patients (71%) by MSP and significantly increasing methylation level in CD patient samples. In addition, we confirmed the methylation level of FHIT gene between normal colon and CD patients. Due to hypermethylation of FHIT gene promoter in CD patients, we observed that the level of FHIT protein is downregulated in CD patient samples compared with normal by IHC analysis. Gene network analysis by GO and metascape for hypermethylated genes in CD patients suggested putative cellular and molecular interactions relevant to IBD pathology. Conclusion Overall, our DNA methylation profile identifies newly hypermethylated genes in CD, as well as paves the way to a better understanding of the role of epigenetics in the pathogenesis of CD, and provides direction for future research in the diagnosis/prognosis or therapeutic treatments for CD.