FIGURE 1.

SPtA triggers caspase‐dependent cell death in human macrophages. (a) Bacterial internalisation (at 1.5 h post‐infection) and (b) PI uptake into MDMs infected with SPtA ED199 or 9150 (at 3 h post‐infection). (c) ELISA quantification of IL‐1β in supernatants of MDMs infected with the indicated SPtA strains (at 3 h post‐infection). (d) Bacterial internalisation and (e) PI uptake into THP1 cells infected with the indicated SPtA strains. (f) ELISA quantification of IL‐1β in THP1 cell supernatants infected with the indicated SPtA isolates. (g) Representative immunoblots (of two biological repeats) of SPtA‐infected THP1 cells showing cleaved products of caspase‐1, caspase‐4 and IL‐18 (arrows). (h, i) PI uptake into SPtA‐infected THP1 cells treated with Z‐VAD‐FMK (h) or Z‐YVAD‐FMK (i). Mean ± SEM from six independent donors in (a–c), 3 (d, f), 5 (e), or 6 (h, i) independent experiments are depicted and were compared by paired Student's t‐test (a, b), matched one‐way ANOVA (c–f) or two‐way ANOVA (h, i). In (d–f) SPtA 9150 was compared to all other strains. * p < .05, ** p < .01, *** p < .001, **** p < .0001 after correction for multiple comparisons; ns, not significant