Urease prevents adherence of Helicobacter pylori to Kato III gastric epithelial cells

The role of urease in Helicobacter pylori adherence to and internalization by Kato III cells was investigated. Kato III cells were incubated with wild -type strains (N6 or P1), with isogenic mutants lacking urease (N6ureB::TnK m or P1ureA::TnMax5) or producing the inactive apoprotein (N6ureG::TnKm), a nd with urease-positive clones recovered after complementation of N6ureB::T nKm with ureAB. Bacteria were stained with the green fluorescent dye PKH2, and the bacteria load of cells was analyzed by flow cytometry. With mutants lacking urease, the bacteria load was considerably increased, in compariso n with the corresponding parental strains (P<.001). With clone K2(3), produ cing larger amounts of urease than N6, a significant reduction of bacteria load was observed, in comparison with the wild type (P<.001). N6ureG::TnKm showed adherence characteristics similar to those of N6. The role of urease in internalization was not clear. Thus, urease significantly inhibits H. p ylori adherence to Kato III cells by a mechanism largely independent of enz ymatic activity.