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. 2021 Jan 17;23(5):e13306. doi: 10.1111/cmi.13306

FIGURE 4.

FIGURE 4

Very long LPS O‐antigen chains interfere with inflammasome activation by SPtA. (a) Invasion of HeLa cells by WT SPtA 9150, ΔfepE or ΔfepE complemented with an EV or a FepE‐encoding plasmid (pfepE). (b) PI uptake and (c) bacterial internalisation into THP1 cells infected with the indicated SPtA 9150 strains. (d) Representative immunoblots (of 3 biological repeats) from cell lysates or supernatants of THP1 cells infected with the indicated SPtA 9150 strains showing cleaved caspase‐1, caspase‐4 and IL‐18 (arrows). (e, f) PI uptake into THP1 cells expressing non‐targeting control (CTRL), CASP4 or ASC‐targeting miRNA30E (miR) infected with the indicated strains of SPtA. (g) PI uptake into DMSO or MCC950‐treated THP1 cells infected with the indicated SPtA 9150 strains. (h, i) Representative fluorescence microscopy image (h) and quantification (i) of ASC specks in THP1‐ASCmRFP cells infected with WT SPtA 9150 (h) or the indicated strains (i). (j) Proposed model of inflammasome activation in human macrophage infected with SPtA. Mean ± SEM from 3 (a, c, f), 4 (b, i), or 5 (e, g) independent experiments. * p < .05, ** p < .01, *** p < .001 for indicated comparisons by one‐way (a–c, i), two‐way (e–g ANOVA after correction for multiple comparisons; ns, not significant