REQUIREMENT OF THE SHIGELLA-FLEXNERI VIRULENCE PLASMID IN THE ABILITYTO INDUCE TRAFFICKING OF NEUTROPHILS ACROSS POLARIZED MONOLAYERS OF THE INTESTINAL EPITHELIUM

Attachment of an array of enteric pathogens to epithelial surfaces is accompanied by recruitment of polymorphonuclear leukocytes (PMN) acros s the intestinal epithelium. In this report, we examine how Shigella-i ntestinal epithelium interactions evoke the mucosal inflammatory respo nse. We modeled these interactions in vitro by using polarized monolay ers of the human intestinal epithelial cell line, T84, isolated human PMNs, and Shigella flexneri. We show that Shigella attachment to T84-c ell basolateral membranes was a necessary component in the signaling c ascade for induction of basolateral-to-apical directed transepithelial PMN migration, the direction of PMN transepithelial migration in vivo . In contrast, attachment of Shigella to the T84-cell apical membrane failed to stimulate a directed PMN transepithelial migration response. Importantly, the ability of Shigella to induce PMN migration across e pithelial monolayers was dependent on the presence of the 220-kb virul ence plasmid, Moreover. examination of Shigella genes necessary to sig nal subepithelial neutrophils established the requirement of a functio nal type III secretion system. Our results indicate that the ability o f Shigella to elicit transepithelial signaling to neutrophils from the basolateral membrane of epithelial cells represents a mechanism invol ved in Shigella-elicited enteritis in humans.