Abnormal Promoter Methylation of Nucleotide-Binding Oligomerization Domain Containing 2 (NOD2) Gene in the Pathogenesis of Crohn’s Disease

Changes in the expression of nucleotide-binding oligomerization domain containing 2 (NOD2) play an important role in the pathogenesis of several autoimmune diseases, such as inflammatory bowel diseases (IBD), including Crohn’s disease (CD) and ulcerative colitis (UC). It seems that epigenetic modifications, including DNA methylation, have an important role in the suppression of gene activity. In this study, the relationship between DNA methylation patterns of the promoter region of the NOD2 gene and the pathogenesis of CD was assessed. Colonic mucosal samples were obtained from 15 Iranian patients with CD and 15 matched healthy controls with no history of autoimmune diseases. After bisulfite conversion of genomic DNA, the DNA methylation status of three CpG sites in the promoter region of the NOD2 gene was determined by the real-time quantitative multiplex methylation-specific PCR assay. Using this approach, we identified a decreased level of methylation of the NOD2 promoter in the colonic mucosa of patients with CD (0.128±0.093 vs. 0.025±0.016, unmethylated DNA in CD vs. healthy controls, respectively, P<0.000). According to our findings, promoter hypomethylation of the NOD2 gene in the colonic mucosa might contribute to the development and severity of CD.