DR3 Regulates Intestinal Epithelial Homeostasis and Regeneration After Intestinal Barrier Injury

Abstract

TNF superfamily member TL1A has been associated with susceptibility and severity of inflammatory bowel diseases. However, the function of TL1A and its receptor DR3 in the development of intestinal inflammation is incompletely understood. We investigated the role of DR3 expressed by intestinal epithelial cells (IEC) during intestinal homeostasis, tissue injury, and regeneration. Clinical phenotype and histological inflammation were assessed in C57BL/6 (WT), Tl1a-/-, and Dr3-/- mice in dextran sulfate sodium (DSS)-induced colitis. We generated mice with an IEC-specific deletion of DR3 (Dr3ΔIEC) and assessed intestinal inflammation and epithelial barrier repair. In vivo intestinal permeability was assessed by Fluorescein isothiocyanate dextran uptake. Proliferation of IEC was analyzed by Bromodeoxyuridine incorporation. Expression of DR3 mRNA was assessed by fluorescent in situ hybridization. Small intestinal organoids were used to determine ex vivo regenerative potential. Dr3-/- mice developed more severe colonic inflammation than WT mice in DSS-induced colitis with significantly impaired IEC regeneration. Homeostatic proliferation of IEC was increased in Dr3-/- mice but blunted during regeneration. Cellular localization and expression of the tight junction proteins Claudin-1 and zonula occudens-1 (ZO-1) was altered leading to increased homeostatic intestinal permeability. Dr3ΔIEC mice recapitulated the phenotype observed in Dr3-/- mice with increased intestinal permeability and IEC proliferation under homeostatic condition and impaired tissue repair and increased bacterial translocation during DSS-induced colitis. Impaired regenerative potential and altered ZO-1 localization was also observed in Dr3ΔIEC enteroids. Our findings establish a novel function of DR3 in IEC homeostasis and post-injury regeneration independent of its established role in innate lymphoid cells and T helper cells.