IL18 and infection: Pretreatment of Caco-2 cells with the pan-caspase inhibitor Z-VAD(OH)-FMK (ZVAD) prior to infection with Δ6 Yptb completely abrogated IL-18 release and cell death compared to the vehicle control (Fig. 2A and B), indicating that caspases mediate inflammasome activation downstream of Δ6 Yptb infection in human IECs.