(A) Polarized T84 cells were intoxicated with 3 nM toxin for 4 hr, and IL-6 and IL-8 were assessed by real-time qPCR. The TLR4 agonist LPS (applied basolaterally, bLPS) and the ER stress-inducing agent thapsigargin (Thap) were used as positive controls.
(B) Polarized Caco-2 cells treated as in (A).
(C) Polarized T84 cells treated as in (A) with or without brefeldin A (BFA) pretreatment and assayed for IL-6 by real-time qPCR.
Open bars represent negative controls. Gray bars represent positive controls. wt CT, wild-type CT; E/E, E110D/E112D mutant; R192G, R192G mutant; CTB, B subunit alone. Data are shown as means ± SEM. *p < 0.05 by ANOVA. See also Figure S1.