a, Flowchart for establishing LPS-induced sepsis mouse model. Briefly, age and sex-matched Irg1−/− or Irg1+/+ mice were i.p. injected with PBS or LPS (20 mg/kg). At 4- or 24-hours post LPS injection, peritoneal leukocytes, serum, and lung were harvested for further analysis.
b, LPS induces ITA accumulation in Irg1+/+ peritoneal leukocytes, but not in those from Irg1−/− mice. Peritoneal leukocytes were freshly isolated as described above in (a), and the intracellular concentration of ITA was measured by LC-MS/MS (n=2–3 mice per group).
c, LPS-challenged Irg1−/− mice exhibit higher serum Il-6 levels than Irg1+/+ controls, as determined by ELISA (n=3–7 mice per group).
d, e, LPS-challenged Irg1−/− mice exhibit more severe lung injury than Irg1+/+ controls. As described above in (a), mouse lungs were harvested and then subjected to histopathological analysis (n=3–6 mice per group). Representative photomicrographs of HE staining are shown (d). Scale bar, 200 μm (upper panels) & 100 μm (lower panels).
f, Irg1−/− mice are more susceptible to LPS-induced mortality. Kaplan-Meier survival curves were determined as described in Methods (n=10 mice per group).
Shown in b, c and e are average values with S.D. P values are calculated using one-way ANOVA for multiple comparisons (c, e). As for the percent survival, P values were determined using log-rank (Mantel-Cox) test comparing each 2 groups (f); *denotes p < 0.05, **denotes p < 0.01 and ****denotes p < 0.0001 for the indicated comparison.