Alterations of epithelial permeability by Helicobacter and IL-1beta in vitro: protective effect of rebamipide

Infection with Helicobacter increases the transcellular passage of macromolecules across the epithelium, and this effect can be prevented by a gastroprotective agent rebamipide. The aim was to gain insight into the mechanisms involved. The HT29-19A intestinal epithelial cells grown on microporous filters as monolayers were incubated in the presence or absence of rebamipide (1 or 2 mM) with: (1) suspension of a wild H. pylori strain, (2) IL-1beta (0.5 ng/ml) + IFN-gamma (2 units/ml). After incubation, the monolayers were submitted to evaluation of apoptosis by using the apoptotic cell death detection ELISA kit and to assessment of epithelial permeability in Ussing chamber where the ionic conductance (G), fluxes of mannitol (J(Man)) and of horseradish peroxidase in both intact (J(HRPi))- and degraded (J(D)) form, were measured. H. pylori increased the intact HRP fluxes across the barrier (J(HRPi) = 17 +/- 20 vs 97 +/- 70 ng/hr/cm2, P < 0.007), an effect prevented by rebamipide (J(HRPi) = 33 +/- 34 ng/hr/cm2, P < 0.006). IL-1beta increased the ionic conductance (G = 5.5 +/- 1.0 and 21.0 +/- 7.0 mS/cm2, P < 0.006), the intact HRP fluxes (J(HRPi) = 18 +/- 15 and 476 +/- 344 ng/hr/cm2, P < 0.006), and the apoptotic index of the cells (AI = 1 +/- 0 vs 3.7 +/- 0.8), all effects prevented by rebamipide (G = 12 +/- 4.9 mS/cm2, J(HRPi) = 79 +/- 38, AI = 1.6 +/- 0.6, P < 0.03 as compared to IL-beta-treated cells). In basal conditions, rebamipide increased the integrity of the barrier (G = 7.5 +/- 2.3 vs 6.0 +/- 1.8 mS/cm2 for controls, P < 0.007). In conclusion, H. pylori as well as IL-1beta, may alter epithelial permeability and rebamipide may exert its protective effect on gastric mucosa by reinforcing the epithelial barrier in normal conditions and by counteracting the deleterious effect of Helicobacter pylori and IL-1beta on macromolecular permeability.