SIGNAL-TRANSDUCTION PATHWAYS INVOLVED IN ENTEROHEMORRHAGIC ESCHERICHIA COLI-INDUCED ALTERATIONS IN T84 EPITHELIAL PERMEABILITY

Enterohemorrhagic Escherichia coli (EHEC) infection is associated with watery diarrhea and can lead to complications, including hemorrhagic colitis and the hemolytic-uremic syndrome. The mechanisms by which the se organisms produce diarrheal disease remain to be elucidated. Change s in T84 epithelial cell electrophysiology were examined following EHE C infection. T84 cell monolayers infected with EHEC O157:H7 displayed a time-dependent decrease in transepithelial resistance. Increases in the transepithelial flux of both [H-3]mannitol and Cr-51-EDTA accompan ied the EHEC-induced decreases in T84 resistance. Altered barrier func tion induced by EHEC occurred at the level of the tight junction since immunofluorescent staining of the tight-junction-associated protein Z O-1 was disrupted when examined by confocal microscopy. Decreased resi stance induced by EHEC involved a protein kinase C (PKC)-dependent pat hway as the highly specific PKC inhibitor, CGP41251, abrogated the EHE C-induced drop in resistance. PKC activity was also increased in T84 c ells infected with EHEC. Calmodulin and myosin light chain kinase play ed a role in EHEC-induced resistance changes as inhibition of these ef fector molecules partially reversed the effects of EHEC on barrier fun ction. These studies demonstrate that intracellular signal transductio n pathways activated following EHEC infection link the increases in T8 4 epithelial permeability induced by this pathogen.