Role of spleen-derived CD11b+Gr-1+ cells in sepsis-induced acute kidney injury.

Abstract

CD11b+Gr-1+ cells play a key role in inflammation and the purpose of this study was to determine whether splenic CD11b+Gr-1+ cells are mobilized to the kidney and lead to acute kidney injury during sepsis. The sepsis model was generated via cecum ligation and puncture (CLP). The mice were randomly distributed into control, sham operated, CLP and CLP+splenectomy (CLPS) groups (n=5-10/group). The percentage of CD11b+Gr-1+ cells in circulating, bone marrow and spleen were determined. Plasma concentrations of interleukin-6, interleukin-1β, creatinine (Cr) and neutrophil gelatinase-associated lipocalin were measured. CD11b+Gr-1+ cells were detected by immunofluorescence and qRT-PCR. Hematoxylin-eosin (HE) and periodic acid-Schiff (PAS) staining and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labelling (TUNEL) were performed. Expression of mammalian target of rapamycin (mTOR), hypoxia-inducible factor-1α (HIF-1α) and cleaved caspase-3 was measured. The percentage of CD11b+Gr-1+ cells in blood was significantly higher in the CLP group and lower in CLPS group. CD11b+Gr-1+ cells in the spleen were significantly lower in the CLP group. In the CLP group, the plasma concentrations of interleukin-6, interleukin-1β, Cr and neutrophil gelatinaseassociated lipocalin were higher. The expression of Gr-1 and CD11b were higher in CLP. The CD11b+Gr-1+ cells were detected in the kidneys of the CLP group. HE, PAS and TUNEL showed inflammatory cell infiltration and cell apoptosis in CLP. Western blot indicated dephosphorylation of mTOR, down-expression of HIF-1α and increased expression of cleaved caspase-3 in sepsis kidney. Splenic CD11b+Gr-1+ cells migrated to the kidney in sepsis, which led to acute kidney injury via the inhibition of mTOR/HIF-1α.