Inhibition of sphingosine kinase 1 (SphK1) suppresses macrophage caspase-1 activation and reduces interleukin (IL)-1β maturation and release. (A) Macrophages were primed with lipopolysaccharide (LPS; 1 μg/ml) for 3 h, in combination with different doses of PF-543 as indicated or control, and subsequently incubated with adenosine triphosphate (ATP; 5 mM) for 30 min. Cell lysates were immunoblotted with IL-1β antibody (left) and results are summarized in the middle panel (n = 3). IL-1β release in supernatants was measured by enzyme linked immunosorbent assay (right, n = 4). (B and C) Mice were subjected to sham surgery or cecal ligation and puncture (CLP). Immediately after surgery, mice were intraperitoneally injected with PF-543 (10 mg/kg) or control. Lung tissues and serum were harvested from mice 24 h after surgery. IL-1β in serum (B) was measured by enzyme-linked immunosorbent assay (n = 4). Lung lysates (C) were immunoblotted to assess caspase-1 activation and IL-1β maturation (n = 3). (A–C) Data are shown as means ± SD, with one-way ANOVA, Tukey post hoc test. ***P < 0.001; ****P < 0.0001.