Inhibition of Rho proteins blocks LPS-induced IL-8 expression by endothelial cells.

Cells were preincubated with (A) 0.1 to 10 ng/mL TcdB-10463 (inhibitor of RhoA, Cdc42, and Rac) or (B) 1 to 100 ng/mL TcdB-1470 (inhibitor of Cdc42 and Rac) for 60 minutes prior to stimulation with 100 ng/ml LPS for 8 hours. Both toxins inhibited LPS-related IL-8 production in HUVEC cultures in a dose-dependent manner. (C) Inhibition of Rho proteins by 10 ng/mL TcdB-10463 prior to stimulation of cells with 100 ng/mL LPS for 4 hours reduced LPS-dependent IL-8 mRNA accumulation, as evidenced by Northern blot. Constitutively expressed message of GAPDH was shown to confirm equal RNA loading. Data presented are mean ± SEM of 4 separate experiments. A representative autoradiograph out of 3 independent experiments (C) is shown.