Innate immune response of porcine gut associated lymphoid tissue to Salmonella enterica serovar Choleraesuis infection

Gut-associated lymphoid tissue (GALT), which includes Peyer's patches and mesenteric lymph nodes, is critical to the discrimination of pathogens from food antigens in the digestive tract of animals. Salmonella enterica is a significant cause of food-borne disease in humans and enteric and systemic disease in pigs. Salmonella actively invades cells, inducing secretion of cytokines and chemokines. The aim of this study was to describe the gene expression pattern of healthy Peyer's patch and characterize early responses of the porcine GALT to Salmonella infection. Changes in porcine GALT gene expression were measured by quantitative RT-PCR and microarray analysis.; Analysis of healthy pigs indicated that mesenteric lymph nodes and jejunal Peyer's patches have similar basal gene expression patterns. In addition, epithelial cell genes represent a "signature" set of genes expressed by jejunal Peyer's patch. Basal gene expression includes high levels of growth and apoptosis-related genes in juvenile pigs Peyer's patches compared to adults.; We studied Salmonella infection after intragastric inoculation in vivo and ex vivo by infection of mucosal sheets in an Ussing chamber. Inflammatory cytokine responses were rapidly and transiently increased after infection of jejunal Peyer's patch with virulent Salmonella serovar Choleraesuis. IL-1beta and IL-8 mRNA levels were consistently increased after Salmonella exposure, both ex vivo and in vivo. Both efficient Salmonella adherence and internalization is needed to induce the innate response. After intragastric infection, IL-1beta and IL-8 mRNA levels were significantly expressed by distal ileal Peyer's patch and positively associated with neutrophil infiltration of the mucosa.; We applied molecular analyses to examine gene expression patterns of intact Peyer's patch. We have utilized the Ussing chamber as an ex vivo method for controlled infection of intestinal mucosa with Salmonella. We have described for the first time the innate response of the porcine GALT to intragastric Salmonella infection. These studies indicate that both jejunal and ileal Peyer's patches can respond to Salmonella infection. However, early inflammatory gene expression in distal ileal Peyer's patch appears to be critical to host defense against Salmonella infection.