Fig 1: CCR2+ classical monocytes and CXCL2/CXCR2 signaling drive lung capillary neutrophil retention after AKI.(A) Schematic of classical monocyte depletion using anti-CCR2 Ab in vivo. (B) Lung monocytes after pretreatment with anti-CCR2 Ab or control IgG. n = 6 per group. (C) Serum BUN indicating kidney injury level on day 1 after AKI. n = 6 per group. (D) Lung immunofluorescence staining after AKI in control versus anti-CCR2 Ab–treated animals. Shown are alveolar and interstitial macrophages (CD68+, red) and neutrophils (Ly6G+, green). Hoechst 33342 dye (blue) was used to visualize nuclei. Scale bar: 100 μm. n = 6 per group. (E) Total number of cell-cell communications inferred by CellChat based on the scRNA-Seq analysis for sham-operated versus AKI mice (also see Supplemental Figure 2). (F) Cell-cell communications from monocytes or macrophages to neutrophils were predicted at single ligand-receptor resolution (unbiased); the neutrophil chemoattractant CXCL2 in monocytes and macrophages and their receptor CXCR2 in neutrophils was predicted to be significantly increased in AKI versus sham groups and are underlined. (G) Lung immunofluorescence staining for Ly6G+ neutrophils (green) from WT C57BL/6 mice injected with anti-CXCL2 or control Ab and subjected to AKI. Scale bar: 100 μm. n = 4–5 per group. The graph shows a quantification of lung neutrophils detected by immunofluorescence. Data represent the mean ± SD. *P < 0.05 and **P < 0.01, by unpaired, 2-tailed Student’s t test.