Fig 1: AKI triggers lung endothelial barrier dysfunction and immune cell accumulation very early after AKI.(A) Lung hematoxylin and eosin stain after sham or 1 to 12 hours after AKI. (B) Alveolar wall thickness measurements after sham or 1 to 12 hours and days 1, 3, and 5 after AKI. (C) Lung neutrophils (Ly6G+, green), alveolar macrophages (CD68high, large, red), and IMs (CD68low, small, red) and quantification after Sham or AKI days 1, 3, and 5 after AKI. DAPI stain (blue) was used to visualize nuclei. (D) Lung Evans blue leakage after sham or 1 to 4 hours after AKI. (E) Lung Evans blue quantification [optical density at 620 nm (OD620) per gram of lung dry weight] after sham or 1 to 4 hours after AKI. (F) Lung electron microscopy and quantification of endothelial tight junction length (in nanometers) at day 1 in sham or day 1 after AKI in wt control or OPN–global KO mice. (G) Lung scRNAseq: expression of endothelial barrier proteins in lung endothelial cells day 1 after sham or AKI; Tjp1: zonula occludens-1 (ZO-1) and claudin-5 (Cdnl5). (H) Lung ZO-1 protein expression [immunofluorescence (IF)]: ZO-1 (red), CD31 (green, marking endothelial cells), DAPI (blue, marking nucleus), and quantification day 1 after sham or AKI. (I) Lung qPCR: ZO-1 expression day 1 after sham or AKI. n = 3 to 6animals per measurement. *P < 0.05, **P < 0.01, and ***P < 0.001.