Fig. 2.

S. mutans induces caspase-1-dependent IL-1β secretion and caspase-independent cell death. a–d THP-1 cells were pretreated with Z-WEHD-FMK (10 μmol · L⁻¹) or Z-VAD-FMK (10 μmol · L⁻¹) for 30 min before S. mutans infection (MOI 50) for 24 h. a Cell culture supernatants were collected and assayed for IL-1β secretion by ELISA. b IL-1β and caspase-1 secreted into the culture supernatant (sup.) and pro-IL-1β and β-actin in the cell lysates (cell) were detected by immunoblotting. The relative western blot band densities were normalised to those of β-actin. c THP-1/ASC-GFP cells were pretreated with Z-WEHD-FMK or Z-VAD-FMK for 30 min before S. mutans infection for 24 h. The graph shows the percentage of cells containing ASC pyroptosomes. d Cell culture supernatants were collected, and the level of the cytoplasmic enzyme LDH was measured. The results represent those from one of three individual experiments. The data are reported as the means ± standard deviations (n = 3). *P < 0.05, **P < 0.01, ***P < 0.001. S.m. means S. mutans