Endothelial-specific Poldip2 knock-out prevents LPS-induced lung injury. (A) Poldip2 EC−/− and Poldip2 EC+/+ littermates were injected with 18 mg/kg LPS. BAL was collected 18 h later and cell counts are represented as averages ± SEM (n = 4–6). $$$P < 0.001 compared to PBS injected Poldip2 EC+/+ mice, ####P < 0.0001 compared to LPS injected Poldip2 EC+/+ mice (two-way ANOVA, with Tukey’s correction). (B) Lungs harvested from mice treated as in (A) were stained with haematoxylin eosin, and show increased lung oedema in Poldip2 EC+/+ (arrows), but not in Poldip2 EC−/− mice after LPS injection. (C) Protein concentration measurement in BAL showing a significant increase after LPS injection. This response was significantly blunted in Poldip2 EC−/− mice (n = 5 in PBS group, n = 6–7 in LPS treated groups). $$P < 0.01 compared to PBS injected Poldip2 EC+/+ mice, #P < 0.05 compared to LPS injected Poldip2 EC+/+ mice (two-way ANOVA, with Tukey’s correction). (D) Lung permeability to Evans blue dye increased after LPS injection in Poldip2 EC+/+ with a significantly lower increase in Poldip2 EC−/− mice (n = 9 for PBS injected groups, n = 11–12 for LPS injected mice, $P < 0.05 compared to PBS injected Poldip2 EC+/+ mice, #P < 0.05 compared to LPS injected Poldip2 EC+/+ mice (two-way ANOVA, with Tukey’s correction)]. (E) Neutrophil-specific staining of LY6G and LY6C showed a significantly increased lung parenchyma infiltration with neutrophils in Poldip2 EC+/+ mice after LPS injection, which was significantly lower in Poldip2 EC−/− mice. Data quantified in (F), represent averages ± SEM (n = 5) $$$P < 0.001 compared to PBS injected Poldip2 EC+/+ mice, #P < 0.05 compared to LPS injected Poldip2 EC+/+ mice (two-way ANOVA, with Tukey’s correction).