Figure 3.

Arginase-1⁺ macrophages promote epithelial cell proliferation. (A–C) Ki67 staining of Arg1^con and Arg1^mko kidneys on day 3 after IRI/CL-NX is shown in (A) and quantified in (B) (total cells) and (C) (interstitial and epithelial cells). Outer medullary Ki67⁺-proliferating epithelial cells are significantly reduced in Arg1^mko kidneys (****P<0.0001, ANOVA). (D and E) TUNEL staining of Arg1^con and Arg1^mko kidneys on day 3 after IRI/CL-NX is shown in (D) and quantified in (E) (ns, not significant; t test). (F and G) Western blot analysis of the cortex and medulla of Arg1^con and Arg1^mko kidneys 3 days after IRI/CL-NX reveals upregulation of arginase-1 selectively in the medulla (F), with a significant reduction in the Arg1^mko kidneys (G) (**P<0.01, *P<0.05, ANOVA). (H) Quantification of F4/80⁺ cells 3 days after IRI/CL-NX demonstrates no difference in macrophage numbers in the two groups. n=5 mice per group.