Regional IFNgamma expression is insufficient for efficacious control of food-borne bacterial pathogens at the gut epithelial barrier.

IFNgamma is critical for host defence against various food-borne pathogens including Salmonella enterica and Listeria monocytogenes, the causative agents of salmonellosis and listeriosis, respectively. We investigated the impact of regional IFNgamma expression at the intestinal epithelial barrier on host invasion by salmonellae and listeriae following oral challenge. Transgenic mice (IFNgamma-gut), generated on an IFNgamma knock-out (KO) background, selectively expressed IFNgamma in the gut driven by the modified liver fatty acid-binding protein (Fabpl(4x at -132)) promoter. Infections with attenuated S. enterica Typhimurium or with L. monocytogenes did not differ significantly in IFNgamma-KO, IFNgamma-gut and wild-type mice. Further, Listeria-specific CD4+ and CD8+ T cells were not altered in IFNgamma-gut mice. Thus, this model indicates that local IFNgamma expression by non-immunological cells in the distal part of the small intestine, caecum and colon is insufficient for prevention of gut penetration by S. enterica Typhimurium and L. monocytogenes.