Pretreatment with S-Nitrosoglutathione Attenuates Septic Acute Kidney Injury in Rats by Inhibiting Inflammation, Oxidation, and Apoptosis

Abstract

Objective: We aimed to investigate the protective effect of s-nitrosoglutathione (SNG) pretreatment on acute kidney injury (AKI) in septic rats.

Methods: We constructed a rat model of sepsis by cecal ligation and puncture and observed the survival of the rats. We obtained kidney and blood samples from rats, observed the pathological damage to the kidney tissues, and evaluated kidney function and the expression levels of inflammatory factors. We also detected the expression of induced nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) in the kidneys by immunohistochemistry and evaluated the apoptosis of kidney tubular epithelial cells (KTEC) by TUNEL.

Results: Pretreatment with SNG significantly reduced the mortality of septic rats, attenuated kidney pathological damage, and decreased the levels of serum creatinine, plasma neutrophil gelatinase-associated lipocalin, and plasma kidney injury molecule-1. Moreover, SNG pretreatment decreased the levels of TNF-α and IL-1β in serum and kidney and reduced the expressions of NO, iNOS, PGE2, and COX-2 in the kidneys. Furthermore, pretreatment with SNG significantly reduced the apoptotic rate of KTEC and decreased the levels of caspase-3 and Bax mRNA, but increased the level of Bcl-2 mRNA.

Conclusion: Pretreatment with SNG has a protective effect on AKI in septic rats, and the specific mechanisms are related to inhibition of inflammation, oxidation, and apoptosis.

Figure 1

Effect of SNG pretreatment on mortality and kidney function. (a) The survival rate of rats in different groups (n = 20 in each group). (b) The pathological changes of kidney (H&E, ×400). (c) Estimation of the kidney tubular injury score. The levels of (d) SCr, (e) pNGAL, and (f) pKIM-1 in different groups. SNG: s-nitrosoglutathione; SCr: serum creatinine; pNGAL: plasma neutrophil gelatinase-associated lipocalin; pKIM-1: plasma renal injury molecule-1. Data are expressed as mean ± SD. ^∗∗∗P < 0.001 vs. the control group; ^#P < 0.05, ^##P < 0.01, and ^###P < 0.001 vs. the CLP group (n = 10 in each group).

Figure 2

Effect of SNG pretreatment on inflammation. (a) The level of TNF-α in serum. (b) The level of TNF-α in the kidney. (c) The level of IL-1β in serum. (d) The level of IL-1β in the kidney. SNG: s-nitrosoglutathione; TNF-α: tumor necrosis factor-α; IL-1β: interleukin 1β. Data are expressed as mean ± SD. ^∗∗∗P < 0.001 vs. the control group; ^###P < 0.001 vs. the CLP group (n = 10 in each group).

Figure 3

Effect of SNG pretreatment on the productions of NO and PGE2 and the expressions of iNOS and COX-2. The productions of (a) NO and (b) PGE2 in different groups; the effect of SNG on the expressions of (c, d) iNOS and (e, f) COX-2 (×200). SNG: s-nitrosoglutathione; NO: nitric oxide; PGE2: prostaglandin E₂; iNOS: inducible nitric oxide synthases; COX-2: cyclooxygenase-2. Data are expressed as mean ± SD. ^∗∗∗P < 0.001 vs. the control group; ^#P < 0.05 and ^###P < 0.001 vs. the CLP group (n = 10 in each group).

Figure 4

Effect of SNG pretreatment on the apoptosis of kidney tubular epithelial cells. (a) The apoptosis of kidney tubular epithelial cells was detected by TUNEL staining (×400). (b) The apoptotic rate was calculated from different groups. (c) Apoptosis-related proteins caspase-3, Bax, and Bcl-2 mRNA were detected by RT-qPCR. SNG: s-nitrosoglutathione. Data are expressed as mean ± SD. ^∗∗∗P < 0.001 vs. the control group; ^#P < 0.05, ^##P < 0.01, and ^###P < 0.001 vs. the CLP group (n = 10 in each group).