Shikonin Suppresses NLRP3 and AIM2 Inflammasomes by Direct Inhibition of Caspase-1
Fig 5
Shikonin Inhibits Caspase-1 Activation.
(A) iBMDMs were primed with 100 ng/mL LPS overnight or were left untreated (ctrl). 30 min before stimulation with 10 μM nigericin, they were subjected to shikonin (5–0 μM) or solvent control (DMSO). Shikonin dose-dependently inhibited caspase-1 activation, which was followed by the presence of 20 kDa (upper blot) and 10 kDa (below) subunits of active caspase-1 in the supernatant. Pro-caspase-1 and β-actin in cell lysate are used as loading controls. Representative Western blot of 3 independent experiments is shown. (B) Activated caspase-1 in iBMDMs treated by nigericin (bold solid), nigericin and 0.5 μM shikonin (solid), LPS only (dashed) or untreated (dotted) was followed by flow cytometry upon binding of fluorescent FAM-YVAD-FMK. Representative of 2 independent experiments is shown. (C) Shikonin (20–0 μM) or DMSO (solvent control) and pancaspase inhibitor Y-VAD-FMK (20 and 10 μM) were tested for in vitro inhibition of caspase-1. Error bars represent SD of triplicate wells.