Figure 2

GlcN inhibits caspase-1 activation and the release of IL-1β, IL-18 and ASC. (A–D) J774A.1 macrophages were incubated for 4 h with LPS (1 µg/ml) followed by incubation for 2 h with GlcN. Cells were then incubated with ATP (5 mM, 0.5 h) or infected with E. coli (30 MOI, 1 h). The expression levels of IL-1β and IL-18 (A), caspase-1 (C), ASC (D) in the supernatants and IL-1β in the cell lysates (B) were analysed by Western blotting. (E) J774A.1 macrophages were incubated for 4 h with LPS (1 µg/ml) followed by incubation for 2 h with GlcN, D-(+)-glucose (Glu), D-glucosamine 3-sulphate (GlcN-3S), D-(+)-galactosamine hydrochloride (GalN) and N-acetyl-D-glucosamine (GlcNAc) for 2 h, followed by incubation with ATP (5 mM) for 0.5 h. The IL-1β expression levels in the supernatants were measured by ELISA. (F) J774A.1 macrophages were incubated for 4 h with LPS (1 µg/ml) or PamsCSK4 (1 µg/ml; for non-canonical inflammasome) followed by incubation for 2 h with GlcN, followed by transfection with poly(dA/dT) (2 µg/ml) or LPS (2 µg/ml) for 6 h or by Salmonella infection (30 MOI) for 2 h. The IL-1β expression levels in the supernatants were measured by ELISA. The ELISA data are expressed as the mean ± SD of separate experiments as indicated. The Western blotting results are representative of three different experiments and the histogram shows the quantification expressed as the mean ± SD for these three experiments. *, *** and **** indicate a significant difference at the level of p < 0.05, p < 0.001 and p < 0.0001, respectively, compared to NLRP3 activator-treated cells. (One-way ANOVA with Dunnett’s multiple comparisons test). The blots in (A–D) were cropped from different gels; full-length blots are included in the “Supplementary Information”.