title: Effect of wild-type Shigella species and attenuated Shigella vaccine candidates on small intestinal barrier function, antigen trafficking, and cytokine release.
abstract: Bacterial dysentery due to Shigella species is a major cause of morbidity and mortality worldwide. The pathogenesis of Shigella is based on the bacteria's ability to invade and replicate within the colonic epithelium, resulting in severe intestinal inflammatory response and epithelial destruction. Although the mechanisms of pathogenesis of Shigella in the colon have been extensively studied, little is known on the effect of wild-type Shigella on the small intestine and the role of the host response in the development of the disease. Moreover, to the best of our knowledge no studies have described the effects of apically administered Shigella flexneri 2a and S. dysenteriae 1 vaccine strains on human small intestinal enterocytes. The aim of this study was to assess the coordinated functional and immunological human epithelial responses evoked by strains of Shigella and candidate vaccines on small intestinal enterocytes. To model the interactions of Shigella with the intestinal mucosa, we apically exposed monolayers of human intestinal Caco2 cells to increasing bacterial inocula. We monitored changes in paracellular permeability, examined the organization of tight-junctions and the pro-inflammatory response of epithelial cells. Shigella infection of Caco2 monolayers caused severe mucosal damage, apparent as a drastic increase in paracellular permeability and disruption of tight junctions at the cell-cell boundary. Secretion of pro-inflammatory IL-8 was independent of epithelial barrier dysfunction. Shigella vaccine strains elicited a pro-inflammatory response without affecting the intestinal barrier integrity. Our data show that wild-type Shigella infection causes a severe alteration of the barrier function of a small intestinal cell monolayer (a proxy for mucosa) and might contribute (along with enterotoxins) to the induction of watery diarrhea. Diarrhea may be a mechanism by which the host attempts to eliminate harmful bacteria and transport them from the small to the large intestine where they invade colonocytes inducing a strong inflammatory response.
authors.affiliation: Mucosal Immunology and Biology Research Center, Massachusetts General Hospital, Charlestown, Massachusetts, United States of America.
authors.forename: Maria
authors.initials: M
authors.lastname: Fiorentino
authors.affiliation: Center for Vaccine Development and the Departments of Pediatrics and Medicine, University of Maryland School of Medicine, Baltimore, Maryland, United States of America.
authors.forename: Myron M
authors.initials: MM
authors.lastname: Levine
authors.affiliation: Center for Vaccine Development and the Departments of Pediatrics and Medicine, University of Maryland School of Medicine, Baltimore, Maryland, United States of America.
authors.forename: Marcelo B
authors.initials: MB
authors.lastname: Sztein
authors.affiliation: Mucosal Immunology and Biology Research Center, Massachusetts General Hospital, Charlestown, Massachusetts, United States of America.
authors.forename: Alessio
authors.initials: A
authors.lastname: Fasano
mesh_terms: D018938:Caco-2 Cells; D002470:Cell Survival; D015169:Colony Count, Microbial; D054884:Host-Pathogen Interactions; D006801:Humans; D007249:Inflammation / Q000276:immunology / Q000382:microbiology; D016209:Interleukin-8 / Q000276:immunology / Q000378:metabolism; D007422:Intestines / Q000382:microbiology; D008954:Models, Biological; D010539:Permeability; D022281:Shigella Vaccines / Q000276:immunology; D012762:Shigella dysenteriae / Q000472:pathogenicity / Q000502:physiology*; D012763:Shigella flexneri / Q000472:pathogenicity / Q000502:physiology*; D019108:Tight Junctions / Q000276:immunology / Q000382:microbiology*; D014613:Vaccines, Attenuated
chemical_list: D016209:Interleukin-8; D022281:Shigella Vaccines; D014613:Vaccines, Attenuated