WORTMANNIN BLOCKS YERSINIA INVASIN-TRIGGERED INTERNALIZATION, BUT NOTINTERLEUKIN-8 PRODUCTION BY EPITHELIAL-CELLS

In response to bacterial infection epithelial cells up-regulate expres sion and secretion of proinflammatory cytokines. Previous work from ou r laboratory showed that basolateral infection of polarized T84 cells with Yersinia enterocolitica induces interleukin-8 (IL-8) secretion in the absence of significant invasion. Here we studied Y. enterocolitic a-induced IL-8 secretion by epithelial HeLa cells as a function of Yer sinia invasion or adhesion. For this pur pose we tried to separated in duction of IL-8 secretion from invasion by treating HeLa cells with si gnal transduction inhibitors prior to infection. While staurosporin an d genistein inhibited both Yersinia invasion and Yersinia-triggered IL -8 secretion, wortmannin, an inhibitor of the phosphatidylinositol-3-p hosphate kinase (PI3-K), blocked invasion of Y. enterocolitica into He La cells but did not show any effect on IL-8 secretion. These results suggest that Yersinia adhesion might be sufficient to induce IL-8 secr etion by epithelial cells. Further analysis demonstrated the requireme nt of the Yersinia invasion locus inv for adhesion-mediated induction of IL-8 secretion. Thus, HeLa cells infected with an E. coli strain ex pressing the Y. enterocolitica inv locus induced IL-8 secretion in the presence and absence of wortmannin. Reverse transcription-polymerase chain reaction analysis revealed that adhesion of inv-expressing Y. en terocolitica or E. coli results in the transcriptional activation of t he IL-8 gene. These results suggest that Y. enterocolitica adhesion to host cells via Inv activates de novo synthesis and secretion of IL-8.