PANETH CELLS ALPHA DEFENSINS- PATHOGENETIC TARGET OF ADOPTIVE T CELL TRANSFER IBD MODEL

Abstract Background & Aims The pathogenesis of inflammatory bowel disease (IBD) remains unclear. Although several murine models of IBD exist, the specific pathological targets are still unknown. To explore the pathogenesis of IBD, this study aimed to analyze the intestinal transcriptome using the SAMP1 Crohn’s disease model and the CD4+ T cell adoptive transfer model. METHODS Model: Chronic ileitis was established in SCID mice by intraperitoneal transfer of CD4+ T cells derived from SAMP1 mice (Fig.1A, Oka, IBD 2014. donor SAMP1 mice: spontaneous ileitis model: Matsumoto, Gut 1998). As control, SCID mice received intraperitoneal PBS injection (no ileitis). Intestinal inflammation was evaluated by body weight (BW), fecal lipocalin-2 (ELISA), and blinded histological scoring (modified Rath score). Transcriptome analysis: Two and four weeks after cell transfer, RNA-stabilized terminal ileum samples were analyzed by microarray (N = 3/group). Paneth cell evaluation: Based on the transcriptome findings, Paneth cells were assessed histologically (cell number and degeneration score) (N = 7/group). RESULTS Transfer of SAMP1-derived CD4+ T cells resulted in BW loss 3 weeks after transfer and the development of ileitis by week 4 (Fig.1A). Transcriptome analysis of the ileum revealed marked downregulation of alpha-defensins (top 9 hits) (Fig.1B). In addition, Reg3a was the top 10 gene. These genes are closely related to Paneth cell function in mice. Therefore, Paneth cells were further evaluated histologically. Interestingly, prior to the onset of ileitis (week 2), Paneth cells showed degeneration, and their numbers were significantly reduced (Fig.1C). These results suggest that transferred CD4+ T cells may specifically target Paneth cells in this IBD model. CONCLUSION Our findings suggest a novel pathogenic mechanism in an IBD model. Paneth cells play a critical role in protecting intestinal stem cells and preventing dysbiosis within the crypt. Beyond IBD, other gastrointestinal disorders, such as graft-versus-host disease–related colitis, leaky gut syndrome, and colon cancer, are also associated with Paneth cell dysfunction. This study provides novel pathological and pharmacological insights into gastrointestinal research.