Fig. 1.

N-3-(oxododecanoyl)-homoserine lactone (C12-HSL), but not N-butyryl homoserine lactone (C4-HSL), increases paracellular permeability across Caco-2 monolayers. Caco-2 cells grown on collagen-coated Transwell filters (12-mm diameter, 0.4-μm pore size) were incubated with the indicated concentrations of C12-HSL (A) or C4-HSL (C) for 4 h. In separate experiments, cells were incubated with 200 μM C12-HSL (B) or 200 μM C4-HSL (D) for the indicated times. Controls were either untreated (CTL) or incubated with vehicle (0.4% DMSO, Veh). Epithelial permeability was determined by measuring paracellular passage of FITC-dextran 20 from the apical side to the basolateral side across Caco-2 monolayers. Values (means ± SD) are expressed as fold change compared with CTL or Veh; n ≥ 4. **P < 0.01 vs. control.