Necrostatin-1 attenuates sepsis-associated acute kidney injury by promoting autophagosome elimination in renal tubular epithelial cells

Abstract

The aim of the present study was to investigate the protective effect of necrostatin-1 (Nec-1) in sepsis-associated acute kidney injury (SA-AKI). An SA-AKI mouse model was established through an intraperitoneal injection of lipopolysaccharide (LPS), and Nec-1 was administered to the mice prior to the establishment of SA-AKI. Renal function and histological changes were evaluated, and the expression levels of microtubule-associated protein light chain 3-II (LC3-II) and p62, as markers of autophagic flux, were detected. Autophagosomes and autolysosomes in renal tubular epithelial cells were also identified using electron microscopy. Pretreatment with Nec-1 could attenuate the LPS-induced increases in the concentrations of blood urea nitrogen (LPS+Nec-1 vs. LPS group, 14.15±4.14 mmol/l vs. 32.54±5.46 mmol/l, respectively; P<0.001) and serum creatinine (11.50±1.67 μmol/l vs. 30.08±4.18 μmol/l, respectively; P<0.001). However, there were no significant differences in the rate of renal tubular epithelial cell necrosis between the groups. In the renal tissues of SA-AKI mice, protein analysis showed that the LC3-II and p62 proteins were increased, while a reverse transcription-quantitative Reverse transcription-polymerase chain reaction analysis detected no increase in LC3-II or p62 mRNA. Additionally, a high number of autophagosomes, but not of autolysosomes, were observed by electron microscopy. When mice were pretreated with Nec-1, the levels of LC3-II and p62 decreased, and a large number of autolysosomes were observed by electron microscopy in the Nec-1 pretreatment group. These results indicated that Nec-1 improved autophagosome elimination, a process that is impaired by LPS, in renal tubular epithelial cells. This potentially enabled Nec-1 to prevent SA-AKI. Furthermore, the findings suggested that the protective effect of Nec-1 may not have involved the inhibition of necroptosis, but may have occurred through the promotion of autophagosome elimination in renal tubular epithelial cells.