RIPK1 ablation in T cells results in spontaneous enteropathy and TNF-driven villus atrophy

RIPK1 is a crucial regulator of cell survival, inflammation and cell death. Human RIPK1 deficiency leads to early-onset intestinal inflammation and peripheral T cell imbalance, though its role in αβT cell-mediated intestinal homeostasis remains unclear. In this study, we demonstrate that mice with RIPK1 ablation in conventional αβT cells (Ripk1^ΔCD4) developed a severe small intestinal pathology characterized by small intestinal elongation, crypt hyperplasia, and duodenum-specific villus atrophy. Using mixed bone marrow chimeras reveals a survival disadvantage of αβT cells compared to γδT cells in the small intestine. Broad-spectrum antibiotic treatment ameliorates crypt hyperplasia and prevents intestinal elongation, though villus atrophy persists. Conversely, crossing Ripk1^ΔCD4 with TNF receptor 1 Tnfr1^-/- knockout mice rescues villus atrophy but not intestinal elongation. Finally, combined ablation of Ripk1^∆CD4 and Casp8^∆CD4 fully rescues intestinal pathology, revealing that αβT cell apoptosis in Ripk1^∆CD4 drives the enteropathy. These findings demonstrate that RIPK1-mediated survival of αβT cells is essential for proximal small intestinal homeostasis. In Ripk1^∆CD4 mice, the imbalanced T cell compartment drives microbiome-mediated intestinal elongation and TNF-driven villus atrophy.