FIG. 1.
Effect of P. aeruginosa on integrity of primary cultured mouse tracheal epithelial cell layers. A. Transepithelial resistance (Rt) of MTEC incubated with P. aeruginosa. PAO1 (106 to 107 CFU) was applied to the apical surface of MTEC (2 × 105 cells) for up to 10 h. Values are the means ± standard deviations (n = 3 to 9 samples/time). The dashed line represents the lower limit of Rt corresponding to maintenance of tight junctions (46). Mechanical injury (mech inj) induced by scraping an uninfected cell layer is shown as a reference. A significant difference at 10 h (P < 0.05) compared to other times is indicated (*). B. Scanning EM of cells obtained 10 h after inoculation with control medium or P. aeruginosa (Pa) as in panel A. The boxed region (center panel) showing bacteria either entering or emerging from the apical membrane of cells is enlarged in the right panel. Bars = 5 μm (left and center panels); 1 μm (right panel).