The protective effect and mechanism of N-acetylcysteine on acute kidney injury by up-regulating Sirtuin3 protein expression in septic mice / 中华急诊医学杂志

ABSTRACT

Objective:To explore the protective effect and mechanism of the antioxidant N-acetylcysteine (NAC) regulating silent information regulator 3 (Sirt3) on acute kidney injury (AKI) in septic mice.Methods:Male C57BL/6 mice were randomly ( random number) divided into the sham operation group (sham), cecal ligation and perforation group (CLP), CLP + NAC (50 mg/kg) and CLP + NAC (100 mg/kg) groups, with 10 mice in each group. The mice were sacrificed 24 h after CLP, and blood and kidney tissue samples were collected. HE staining was used to evaluate the pathological damage of the kidney tissue of mice in each group. ELISA was used to detect serum creatinine (Scr), urea nitrogen (BUN), kidney injury molecule 1 (KIM-1) and neutrophil gelatinase-associated apolipoprotein (NGAL) levels. Immunohistochemistry was used to detect the expression of Sirt3 protein in kidney tissue. RT-qPCR was used to detect the level of Sirt3 mRNA. Mitochondrial damage of renal tubular epithelial cells was observed under transmission electron microscope, and the mitochondrial density was calculated. Meanwhile, the levels of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), catalase (CAT) and malondialdehyde (MDA) in the renal cortex were also detected. Results:Compared with the sham group, in the CLP group, the pathological damage of renal tissue was significantly aggravated ( P<0.001), and the levels of renal function indicators (Scr, BUN, KIM-1 and NGAL) were all increased significantly (all P<0.001). The protein and mRNA expression of Sirt3 were all significantly decreased (all P<0.001), the mitochondrial structure damage of renal tubular epithelial cells was increased, and the mitochondrial density was significantly decreased ( P<0.001). The levels of antioxidant enzymes (SOD, GSH-Px and CAT) in the renal cortex were all significantly decreased (all P<0.001), while the lipid peroxide MDA was significantly increased ( P<0.001). Compared with the CLP group, the renal injury score and renal function indexes (Scr, BUN, KIM-1 and NGAL levels) in the 50 mg/kg NAC pretreatment group were decreased, and the levels of SOD, GSH-Px and CAT in renal tissue were increased, but the differences were not significant. However, pretreatment with 100 mg/kg NAC significantly reduced the pathological damage of kidney tissue caused by CLP ( P<0.001), and significantly decreased the levels of Scr, BUN, KIM-1 and NGAL (all P<0.001). The expression of Sirt3 protein [(50.20±2.79) vs.(20.00±0.75), P<0.001] and mRNA [(0.57±0.07) vs. (0.41±0.07), P<0.001] were all significantly increased. The mitochondrial structure of renal tubular epithelial cells was more stable, and the mitochondrial density was significantly increased [(0.60±0.05) vs. (0.43±0.06), P<0.001]. The levels of SOD [(67.37±3.79) U/mg vs. (21.09±0.89) U/mg, P<0.001], GSH-Px [(265.61±9.61) U/mg vs. (180.00±3.31) U/mg, P<0.001] and CAT [(8.58±0.65) U/mg vs. (5.19±0.58) U/mg, P<0.001] were all significantly increased, while the expression level of MDA was significantly reduced [(40.36 ±1.79) vs. (83.81 ±1.70), P<0.001]. Conclusions:NAC can significantly reduce renal pathological damage, improve renal function, maintain mitochondrial structure stability and reduce oxidative stress levels in septic mice by up-regulating Sirt3 protein expression, and has a significant protective effect on CLP-induced AKI.