Vibrio cholerae-induced cellular responses of polarized T84 intestinal epithelial cells are dependent on production of cholera toxin and the RTX toxin

To study the utility of in vitro-polarized intestinal cell monolayers for m odeling Vibrio cholerae-host cell interactions, we added live V. cholerae b acteria to the apical surfaces of polarized T84 cell monolayers and monitor ed changes in electrical properties. We found that both classical and El To r strains produce cholera toxin after addition to the monolayer, but induct ion is most likely due to medium components rather than bacterium-cell inte ractions. We also found that the RTX toxin is produced by El Tor strains. T his toxin caused a loss of the barrier function of the paracellular tight j unction that was measured as a decrease in transepithelial resistance. This decrease occurred when bacteria were added to either the apical or basolat eral surfaces, indicating that the RTX toxin receptor is expressed on both surfaces. These results are discussed with regard to the applicability of t he polarized T84 cell monolayers as an in vitro model of host-pathogen inte ractions.