Enteric Salmonella Infection Inhibits Paneth Cell Antimicrobial Peptide Expression

Abstract

Paneth cells, highly secretory epithelial cells found at the bases of small intestinal crypts, release a variety of microbicidal molecules, including α-defensins and lysozyme. The secretion of antimicrobials by Paneth cells is thought to be important in mucosal host defense against invasion by enteric pathogens. We explored whether enteric pathogens can interfere with this arm of defense. We found that oral inoculation of mice with wild-typeSalmonella entericaserovar Typhimurium decreases the expression of α-defensins (called cryptdins in mice) and lysozyme. Oral inoculation withSalmonellaserovar Typhimurium strains that are heat killed, lack the PhoP regulon, and lack the SPI1 type III secretion system or withListeria monocytogenesdoes not have this effect.Salmonellamay gain a specific survival advantage in the intestinal lumen by decreasing the expression of microbicidal peptides in Paneth cells through direct interactions betweenSalmonellaand the small intestinal epithelium.