FIG 1.

P. aeruginosa T3SS effector ExoU inhibits caspase-1 and IL-1β activation during infection. (A) Wild-type (WT) and caspase-1/11^−/− BMDMs were treated with sterile saline solution (C) or inoculated with P. aeruginosa strains as indicated (also see Table 1). Pro-caspase-1 (47 kDa), active caspase-1 (20 kDa), and active IL-1β (17 kDa; see also boxed section in the 60-min time point blots) were measured over time in TCA-concentrated supernatants by Western blotting. Note that in this and subsequent blots, the lanes immediately to the right of the molecular weight marker (MWM) spots are intentionally empty. (B) Pro-caspase-1, active caspase-1, active IL-1β, and β-actin (loading control) were measured in WT and caspase-1/11^−/− BMDM lysates collected under control or P. aeruginosa inoculation conditions. (C) Pro-caspase-1 and active caspase-1 were measured in WT BMDM TCA-concentrated supernatants from control or P. aeruginosa strains complemented with plasmids expressing either wild-type ExoU or activity-null ExoU (S142A). MOI, multiplicity of infection. All Western blots are representative of 3 independent experiments.