Figure 4

Effect of caspase-1 inhibition on IL-1 β release in RAW 264.7 macrophages. The cells were primed for 3 h by LPS (25 ng/ml) and subsequently exposed to silica particles after 6 h. The caspase-1 inhibitor zYVAD (10 μM) was added 1 h prior to exposure to MinUsil 5 (MinU, 200 μg/ml) (A) and 200 μg/ml Si50, fumed silica and fused silica (B), and the IL-1β responses were determined by ELISA. For fused silica, particles after wet sedimentation were used. In A, B the IL-1β levels represent 6 experiments, and are presented as mean ± SD of fold change. * = p < 0.05 significant different from particle-stimulated cells without zYVAD, using Kruskal-Wallis test with Dunn’s Multiple Comparison test as a post-test. C) Levels of pro-IL-1β. The cells were pre-treated with and without LPS for 3 h, and exposed to with Si50 (200 μg/ml) for 6 h and assessed for pro-IL-β levels by Western analysis. A representative Western blot is shown. In the lower part the band intensity of this experiment is shown.