Figure 4.

Role of neutrophils in the protective effects of dexamethasone against ischemic acute kidney injury. (A) RB6–8C5 mAb (anti-Ly-6G and Ly-6C monoclonal antibody, 0.08 mg/mice, intraperitoneal) administered 24 h earlier caused profound neutropenia compared with mice that received the κ isotype control antibody. Blood neutrophil count (% of neutrophils, after red cell lysis) was determined immediately before the induction of renal IRI by flow cytometry. Representative picture from FACS analysis with the gated area containing neutrophils. (B) Renoprotective effects of dexamethasone against mice ischemic AKI are neutrophil independent. Neutrophil-depleted mice were not protected against renal IRI compared with the group that received the κ isotype antibody. Serum creatinine was similar in the group that received the κ isotype control antibody compared with the group that was administered normal saline as vehicle (I/R+V+). Serum creatinine after renal IRI was significantly reduced in mice with normal neutrophil count (I/R+Dex+) and in the neutrophil-depleted mice that received dexamethasone (I/R+Neutro-Dex+, 8 mg/kg, intraperitoneal) 1 h before ischemia. **P < 0.01, sham versus I/R+V+ and sham versus I/R+κ isotype; *P < 0.05, I/R+V versus I/R+Dex and I/R+κ isotype versus I/R+Neutro−Dex+. All serum creatinine measurements were performed 24 h after reperfusion. n = 6–8 mice/group. (C) Renal histopathology. Hematoxylin and eosin–stained sections are from the outer medulla (representative images of at least three experiments). Infiltrating neutrophils after renal IRI in the kidney parenchyma were strikingly reduced in the neutrophil-depleted mice.