Figure 2.

Staphylococcus aureus alters the permeability of cultured RPE cells to fluorophore-conjugated dextrans. Intact monolayers of human RPE cells in 0.4-μm transwells were infected with S. aureus 8325-4 at a concentration of 10⁴ cfu/mL (MOI = 0.01), and diffusion of 4-kDa FITC- dextran (A) and 70-kDa FITC-dextran (B) across the monolayer was assessed by fluorescence spectrometry of the bottom chamber at 4, 6, and 8 hours after bacterial inoculation of the top chamber. No significant differences were observed between the uninfected wells and infected wells after 4 and 6 hours. However, after 8 hours the fluorescence intensity in the bottom chamber was significantly higher (P < 0.0001) than in the uninfected groups. Values represent the mean concentration of the conjugate in the bottom chamber ± SD (N ≥ 3 at each time point), based on extrapolation from a standard curve of the fluorimetry of known FITC-dextran concentrations.