2557-P: Epigenetic Remodeling of Small Intestinal Epithelium by High-Fat Diet

Introduction and Objective: High-fat diet (HFD) is a critical contributor to metabolic disease, frequently triggering DNA hypermethylation in the small intestinal epithelium (SIE). While their specific influence on the expression and functionality of key genes is not fully understood. We elucidated HFD-altered DNA methylation in SIECs and its effect on functional gene regulation. Methods: C57BL/6 mice were fed a normal diet or HFD for 16 weeks. SIE tissues were harvested, and transcriptomic and methylomic profiles were generated using RNA-seq and RRBS. Integrative analysis identified hypermethylated, down-regulated molecules, whose functions were then explored. Results: We identified three genes encoding secreted proteins—Tgfb3, Pla2g5, and Prf1—that exhibited concurrent DNA hypermethylation and transcriptional downregulation. Notably, Prf1 displayed the most pronounced elevation in methylation level and the most significant downregulation. As a core cytotoxic effector molecule predominantly expressed in the granules of cytotoxic T lymphocytes (CTLs) and natural killer (NK) cells, Prf1 was further validated in human SIE transcriptome sequencing data, showing highest expression in CD16+CD56dim NK cells. In addition, genes encoding transcription factors (Prdm1, Pax5, and Aff3) were significantly hypermethylated and downregulated. Furthermore, we observed that genes encoding membrane proteins (Glp1r, Slc43a3, Selplg, Cd247, Rcsd1, and Plaur) displayed increased methylation and reduced expression. Conclusion: The HFD remodels DNA methylation patterns in SIECs, thereby leading to the downregulation of secreted proteins. This epigenetic alteration may significantly impact local immune homeostasis within the intestinal epithelium. Furthermore, the observed hypermethylation and concomitant suppression of Glp1r in SIECs provide a novel epigenetic perspective for understanding the pathogenesis of metabolic diseases. Disclosure R. Yang: None. X. Li: None. F. Sun: None. L. Jiang: None. R. Duan: None. Y. Zhao: None. J. Li: None. C. Wang: None. S. Liu: None. Funding Department of Science and Technology of Shanxi Province (202404010920011, 202304021301066, 202204051002029), Shanxi Bethune Hospital (2024AOXIANG03)