Fig. 6.

Deletion of S1PR3 precludes the protective effects of S1P lyase inhibition in polymicrobial sepsis.

(a) S1pr3^−/− mice were treated with THI for 3 days in drinking water (50 mg/L, ~12.5 mg/kg/day) prior to PCI induced by i.p. injection of a defined human stool suspension (PCI, 3.5 µl/g, n = 10). Sham treated animals were injected with 0.9% saline solution (n = 5). Mice were then treated for 10 d with antibiotic starting 8 h after infection and every 12 h. (b) Kaplan-Meier survival plots for 14 days, *p<0.05 compared to sham (Gehan–Breslow–Wilcoxon test). (c) Levels of S1P in plasma and lung were measured 24 h after PCI by LC-ESI-MS/MS (n = 5). (d) Leakage of serum albumin into the lung lumen was determined in BALF by ELISA 24 h after sepsis induction (n = 5). (e) Bacterial load of aerobic and anaerobic bacteria in lungs, BALF, and whole blood was measured 24 h after PCI (n = 5), *p<0.05 compared to sham animals (Kruskal-Wallis One Way Analysis of Variance on Ranks with a post-hoc Dunn's multiple comparison). Box plots: middle band indicates median; whiskers indicate minimum and maximum values; symbols indicate individual animals. (f) Cytokine levels and (G) markers of tissue damage were analysed in plasma 24 h after sepsis induction in animals ± THI treatment (n = 5). (c, d, f, g) Data are means ± SEM, *p<0.05 compared to untreated sham animals (One-way ANOVA with a post-hoc Bonferroni's multiple comparison test).