Intraepithelial lymphocyte-derived interferon-γ evokes enterocyte apoptosis with parenteral nutrition in mice

Total parenteral nutrition (TPN) results in an increase in intraepithelial lymphocyte (IEL)-derived interferon-gamma (IFN-gamma) expression as well as an increase in epithelial cell (EC) apoptosis. This study examined the role that IEL-derived IFN-gamma has in the increase in EC apoptosis. Mice received either TPN or oral feedings for 7 days. Small bowel EC apoptosis significantly rose in mice receiving TPN. The administration of TPN also significantly increased IEL-derived IFN-gamma and Fas ligand (FasL) expression. EC apoptosis in IFN-gamma knockout (IFNKO) mice that received TPN was significantly lower than in wild-type TPN mice. Sensitivity of EC to Fas-mediated apoptosis in IFNKO mice was significantly lower than in wild-type TPN mice. Apoptosis in Fas-deficient and FasL-deficient mice that received TPN was significantly lower than in wild-type mice that received TPN. The TPN-induced increase in IFN-gamma expression appears to result in an increase in Fas-L expression and EC sensitivity to Fas, with a resultant increase in EC apoptosis. This may well be one of the mediators of increased EC apoptosis observed with TPN administration.