Tehran University of Medical Sciences Immunology and Genetics Journal 2645-4831 6 3 2023 09 22 108 114 Golshid Sanati Department of Immunology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran Mehrdad Noruzinia Department of Medical Genetics, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran Davood Jafari Network of Immunity in Infection, Malignancy and Autoimmunity (NIIMA), Universal Scientific Education and Research Network (USERN), Boston, MA, USA Mohammad Ahmadvand Department of Medical Genetics, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran Shahram Teimourian Department of Immunology, School of Medicine, Zanjan University of Medical Sciences, Zanjan, Iran Naser Ebrahimi Daryani Department of Genetics, School of Medicine, Iran University of Medical Sciences, Tehran, Iran Sara Hanaei Department of Internal Medicine, Division of Gastroenterology, Imam Khomeini Hospital, Tehran University of Medical Sciences, Tehran, Iran Nima Rezaei Research Center for Immunodeficiencies, Pediatrics Center of Excellence, Children's Medical Center, Tehran University of Medical Sciences, Tehran, Iran; 4 Department of Immunology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran; Network of Immunity in Infection, Malignancy and Autoimmunity (NIIMA), Universal Scientific Education and Research Network (USERN), Tehran, Iran 2024 08 04 2024 08 09 Background: Changes in the expression of nucleotide-binding oligomerization domain containing 2 (NOD2) play an important role in the pathogenesis of a variety of autoimmune diseases including inflammatory bowel diseases (IBDs). Epigenetic modifications, including DNA methylation, are considered an important mechanism in the suppression of gene activity. In this study, we investigated the relationship between DNA methylation patterns of the promoter region of the NOD2 gene and the pathogenesis of Crohn’s disease (CD). Methods: Colonic mucosa samples were obtained from 15 Iranian patients with IBD and 15 age- and sex-matched healthy controls with no history of autoimmune disease. After the 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 (QM-MSP) assay. Results: Using this approach, we identified that IBD patients showed a decreased level of methylation of the NOD2 promoter in the colonic mucosa than did the healthy controls. (Unmethylated DNA in Crohn's disease vs. healthy controls; 0.128±0.093 vs. 0.025±0.016, P<0.000). Conclusion: According to our findings, promoter hypomethylation of the NOD2 gene in the colonic mucosa might contribute to the development and severity of CD. Furthermore, aberrant DNA methylation levels are expected to serve as a clinically useful risk marker. https://igj.tums.ac.ir/index.php/igj/article/view/142 https://igj.tums.ac.ir/index.php/igj/article/download/142/127