(A) hMDM incubated with conditioned supernatant from toxin-proficient (TcdA+,TcdB+) or toxin-deficient (TcdA−,TcdB−) C. difficile for 4 h, then the supernatant assessed for IL-1β and IL-18. (B) LPS-primed (10 ng/ml, 3 h) monocytes or hMDM were treated with a dose titration of either TcdB or TcdA for 3 h. Supernatants were harvested and assessed for IL-1β. (C) Immunoblot of lysate from LPS treated (10 ng/ml, 3 h) monocytes or hMDM probed for either Pyrin or actin. Representative of 3 independent experiments. (D) LPS-primed (10 ng/ml, 3 h) monocytes or hMDM were preincubated for 15 min with the vehicle alone, CP-456,773 (2.5 μM), VX-765 (40 μM), or colchicine (2.5 μM), then stimulated with TcdB (20 ng/ml), nigericin (8 μM), or needletox (25 ng/ml) for 2.5 h. The supernatant was assessed for IL-1β and LDH activity or (E) IL-1β and caspase-1 cleavage by immunoblot. Mean and SEM shown for 3 donors or immunoblots representative of 3 independent experiments. * p < 0.05, n.s. not significant. The underlying data can be found in the summary data file in the tab Fig 1A, 1B and 1D.