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

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.

Protective effect and mechanism of Baicalin on acute kidney injury in septic mice / 中华危重病急救医学

Objective:To observe the protective effect and mechanism of different doses of Baicalin (BAI) on acute kidney injury (AKI) in septic mice.Methods:According to the random number table, 100 mice were divided into sham operation group (Sham group), cecal ligation and perforation (CLP) induced sepsis model group (CLP group) and BAI pretreatment groups. The mice in BAI pretreatment groups were divided into low-, medium- and high-dose groups (BAI-L+CLP, BAI-M+CLP, BAI-H+CLP groups), with 20 mice in each group. A murine sepsis associated-acute kidney injury (SA-AKI) model was reproduced using CLP. The mice in the Sham group were only opened and closed the abdomen, without ligating or perforating the cecum. The mice in the BAI pretreatment groups were given BAI 25, 50 and 100 mg/kg daily for 3 days, and CLP was performed at 6 hours after administration of BAI at the 3rd day to reproduce sepsis model. The mice in the Sham group and CLP group were given the same amount of distilled water as control. Ten mice were sacrificed at 24 hours after operation to collect orbital blood for renal function determination [serum creatinine (SCr), blood urea nitrogen (BUN), plasma neutrophil gelatinase-associated lipocalin (pNGAL) and plasma kidney injury molecule-1 (pKIM-1)] by enzyme linked immunosorbent assay (ELISA). The kidney tissue was collected to observe the kidney tissue injury under light microscope after hematoxylin-eosin (HE) staining. The TdT-mediated dUTP nick-end labeling (TUNEL) was used to detect the apoptosis of renal tubular epithelial cells. Western blotting was used to detect the expression of cell FLICE like inhibitory protein (c-FLIP) in renal tissue. The remaining 10 mice in each group were used to calculate the survival rate of 7 days after operation.Results:The renal tubular epithelial cells in the CLP group were massively degenerated with necrosis, the renal tubular lumen was significantly expanded, and inflammatory cells were widely infiltrated in the renal interstitium. Furthermore, the renal function deteriorated rapidly. Compared with the CLP group, the renal function of mice pretreated with low dose of BAI was improved, but the difference was not significant. Compared with the CLP group, the renal function in the mice pretreated with medium and high doses of BAI was significantly improved, the SCr, BUN, pNGAL and pKIM-1 were significantly reduced [SCr (μmol/L): 135.16±5.18, 125.70±5.26 vs. 170.42±5.42; BUN (mmol/L): 33.59±1.77, 27.29±1.61 vs. 45.68±1.39; pNGAL (μg/L): 91.29±4.68, 73.40±3.77 vs. 131.50±6.55; pKIM-1 (μg/L): 6.34±0.30, 5.51±0.35 vs. 8.03±0.29; all P < 0.01], the pathological injury of renal tissue was significantly decreased, the apoptotic number of renal tubular epithelial cells was significantly reduced (cells/HP: 16.20±0.49, 13.10±0.66 vs. 29.60±0.49, both P < 0.01), and the expression of c-FLIP protein in renal tissue was significantly increased [c-FLIP protein (c-FLIP/GAPDH): 0.35±0.02, 0.46±0.02 vs. 0.21±0.01, both P < 0.01]. No mouse in the Sham group died within 7 days. Compared with the CLP group, the average survival time of the mice within 7 days in the BAI-L+CLP, BAI-M+CLP and BAI-H+CLP groups was significantly prolonged with a dose-dependent manner (days: 3.5±2.5, 5.4±2.2, 5.9±1.9 vs. 2.1±1.2; Log-Rank test: χ2 = 73.410, P < 0.001). Conclusion:Pretreatment with medium and high doses of BAI can significantly improve the renal function in mice with SA-AKI, decrease the pathological damage and increase the survival of mice, and its mechanism may be related to promoting the increase of c-FLIP protein expression and inhibiting cell apoptosis.

Protective effect of mitochondria-targeted antioxidant peptide SS-31 in sepsis-induced acute kidney injury / 中华危重病急救医学

Objective:To study the effect and mechanism of mitochondria-targeted antioxidant peptide SS-31 on sepsis-induced acute kidney injury (AKI).Methods:Sixty adult male C57BL/6 mice were randomly divided into four groups according to the random number table method: sham group (10 mice), positive control group (10 mice), sepsis model group (20 mice), and SS-31 peptide group (20 mice). The sepsis-induced AKI mouse model was reproduced by cecal ligation and puncture (CLP). The sham group only received laparotomy. SS-31 peptide (5 mg/kg) was intraperitoneally injected in SS-31 peptide group and positive control group 30 minutes after the operation, while an equivalent amount of normal saline was given in sham group and sepsis model group for 7 days. The blood samples were collected 24 hours after the operation from orbit, and the serum was collected to test the serum creatinine (SCr) and blood urea nitrogen (BUN). The mice were sacrificed 7 days after surgery. The kidney tissues were collected to observe the pathologic structure changes under the hematoxylin-eosin (HE) staining by light microscope. And the mitochondrial ultrastructure was checked under the transmission electron microscope. Cell apoptosis was detected by terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling method (TUNEL). The expression level of peroxisome proliferator-activated receptorγ coactivator-1α (PGC-1α), adenosine monophosphate-activated protein kinase (AMPK), and cleaved caspase-3 protein were tested by Western blotting.Results:Compared with sham group, the levels of SCr and BUN were significantly increased in sepsis model group [SCr (μmol/L): 93.12±11.80 vs. 32.94±3.37, BUN (mmol/L): 41.36±6.48 vs. 9.49±3.58, both P<0.05]. The expression levels of AMPK, PGC-1α and cleaved caspase-3 protein increased (AMPK/β-actin: 0.30±0.02 vs. 0.12±0.01, PGC-1α/β-actin: 0.38±0.03 vs. 0.16±0.02, cleaved caspase-3/β-actin: 0.20±0.01 vs. 0.11±0.02, all P<0.05). HE staining showed that inflammatory cell was infiltrated, glomerular basement membrane was exposed and vacuole-like transparent casts were found in the lumen. Mitochondria were damaged under electron microscope with swelling, ridge disappearance and ruptured membranes, with increasing of apoptotic cells [cells: 24.00 (18.75, 31.00) vs. 2.00 (0.72, 3.25) , P<0.05]. Meanwhile, compared with sepsis model group, the levels of SCr, BUN and the expressions of AMPK, PGC-1α, cleaved caspase-3 protein were significantly decreased in the SS-31 peptide group [SCr (μmol/L): 71.33±10.14 vs. 93.12±11.80, BUN (mmol/L): 27.00±5.52 vs. 41.36±6.48, AMPK/β-actin: 0.23±0.01 vs. 0.30±0.02, PGC-1α/β-actin: 0.27±0.02 vs. 0.38±0.03, cleaved caspase-3/β-actin: 0.13±0.01 vs. 0.20±0.01, all P < 0.05]. HE staining showed that cell swelling reduced, the mitochondrial structure was intact, the ridge swelling was also reduced, and the membrane structure was relatively intact, the number of apoptotic cells was significantly reduced [cells: 13.00 (9.00, 16.50) vs. 24.00 (18.75, 31.00) , P<0.05]. Conclusion:The protective effect of SS-31 peptide on organ dysfunction induced by sepsis-induced AKI is related to maintaining mitochondrial homeostasis and inhibiting cell apoptosis.

Protective effects of Klotho protein on acute kidney injury in septic mice and its mechanism / 中华危重病急救医学

Objective? To? investigate? the? protective? effects? of? Klotho? protein,? a? kind? of? single-pass?transmembrane?protein,?on?acute?kidney?injury?(AKI)?in?septic?mice?and?its?mechanism.? Methods? Sixty?SPF?healthy?male?C57BL/6?mice?(6-8?weeks)?were?randomly?divided?into?sham?operation?group?(Sham?group),?sepsis?model?group?(CLP?group)?and?Klotho?protein?injection?group?(CLP+KL?group),?with?20?in?each?group.?The?septic?AKI?mice?model?was?established?by?cecal?ligation?and?puncture?(CLP);?Sham?group?had?the?same?procedure?except?that?the?cecal?was?not?ligated.?The?CLP+KL?group?was?received?Klotho?protein?(0.02?mg/kg)?by?intraperitoneal?consecutive?injection?for?4?days?after?operation;?Sham?group?and?CLP?group?were?injected?with?the?same?amount?of?saline.?Blood?samples?were?obtained?at?24?hours?after?operation,?the?levels?of?serum?creatinine?(SCr)?and?urea?nitrogen?(BUN)?were?measured?by?sarcosine?oxidase?and?urease?method.?The?mice?were?sacrificed?under?anesthesia?at?5?days?after?operation?to?harvest?renal?tissues,?and?the?pathological?damage?of?the?kidney?was?evaluated?by?hematoxylin-eosin?(HE)?staining.?The?ultrastructure?of?mitochondria?in?mouse?renal?tubular?epithelial?cells?was?observed?under?transmission?electron?microscope.?The?levels?of?reduced? glutathione?hormone?(GSH),?malondialdehyde?(MDA)?and?nitric?oxide?synthase?(NOS)?in?mitochondrion?were?determined?by?micro-enzyme?method,?thiobarbituric?acid?method,?colorimetry?method,?respectively.?The?protein?expressions?of?Klotho,?Bcl-2?and?cytochrome?C?(Cyt?C)?were?detected?by?Western?Blot.? Results? The?pathological?structure?of?the?kidneys?in?the?Sham?group?was?clear?and?intact.?Compared?with?the?Sham?group,?the?renal?tissue?edema?of?the?mice?in?the?CLP?group?was?significant,?and?the?transparent?tube?type?was?observed?in?the?small?lumen,?and?the?interstitial?inflammatory?cells?infiltrated;?the?levels?of?SCr?and?BUN?were?significantly?increased?[SCr?(μmol/L):?182.60±6.97?vs.?47.20±5.37,?BUN?(mmol/L):?53.70±5.12?vs.?18.70±2.62,?both?P?<?0.01];?the?mitochondria?were?swollen?and?deformed,?the?sputum?structure?was?destroyed,?the?matrix?density?was?decreased,?the?outer?membrane?was?lost,?and?the?levels?of?MDA,?GSH?and?NOS?were?significantly?increased?[MDA?(μmol/g):?1.172±0.046?vs.?0.746±0.094,?GSH?(μmol/g):?5.765±0.059?vs.?4.223±0.072,?NOS?(kU/g):?0.91±0.05?vs.?0.68±0.03,?all?P?<?0.01];?the?protein?expressions?of?Klotho?and?Bcl-2??in?renal?tissue?were?decreased,?and?the?protein?expression?of?Cyt?C?was?increased?(Klotho/β-actin:?0.188±0.020?vs.?0.538±0.024,?Bcl-2/β-actin:?0.311±0.010?vs.?0.391±0.015,?Cyt?C/β-actin:?0.226±0.010?vs.?0.135±0.006,?all??P?<?0.01).?Comparing?with?the?CLP?group,?the?glomerular?and?tubular?tissue?epithelial?edema?and?the?small?lumen?in?the?CLP+KL?group?were?reduced;?the?levels?of?SCr?and?BUN?were?significantly?decreased?[SCr?(μmol/L):?85.70±7.23?vs.?182.60±6.97,?BUN?(mmol/L):?35.30±3.50?vs.?53.70±5.12,?both?P?<?0.01];?the?mitochondrial?structure?was?relatively?intact;?the?levels?of?MDA,?GSH?and?NOS?were?significantly?decreased?[MDA?(μmol/g):?0.958±0.072?vs.?1.172±0.046,?GSH?(μmol/g):?4.756±0.107?vs.?5.765±0.059,?NOS?(kU/g):?0.79±0.02?vs.?0.91±0.05,?all?P?<?0.01];?the?protein?expressions?of?Klotho,?Bcl-2?were?significantly?increased,?but?the?protein?expression?of?Cyt?C?was?significantly?decreased?(Klotho/β-actin:?0.336±0.011?vs.?0.188±0.020,?Bcl-2/β-actin:?0.474±0.017?vs.?0.311±0.010,?Cyt?C/β-actin:??0.168±0.006?vs.?0.226±0.010,?all?P?<?0.01).? Conclusion? Klotho?protein?has?significant?protective?effects?on?AKI?in?septic?mice,?and?its?mechanism?is?related?to?maintaining?mitochondrial?structural?integrity?and?oxidative?stress?response.

Expression and significance of c-FLIP protein in sepsis mice with acute kidney injury / 中华危重病急救医学

Objective To observe the expression of cellular Fas-associated death domain-like interleukin-1β converting enzyme inhibit protein (c-FLIP) in sepsis mice with acute kidney injury (SAKI) and explore its significance. Methods Thirty male ICR mice were divided into the normal control group (Normal group), sham operation group (Sham group) and SAKI group by random number table method, with 10 mice in each group. The SAKI model of mice was established by cecal ligation and puncture (CLP); the Sham group was not ligated and the cecum was not punctured, and other surgical procedures were the same as the SAKI group; the Normal group did not experience any treatment. The serum and renal tissues of mice in each group were harvested 24 hours after CLP model establishment. The levels of serum creatinine (SCr) and blood urea nitrogen (BUN) were detected by enzyme linked immunosorbent assay (ELISA). The renal tissues were stained with hematoxylin-eosin (HE), and the pathological changes of renal tissues were observed under light microscope and the severity of injury was determined. The expression of c-FLIP in renal tissues was detected by immunohistochemistry. The expression of c-FLIP, Bax and caspase-3 protein in renal tissue was detected by Western Blot. The correlation between c-FLIP expression and Bax, caspase-3 protein expressions in renal tissues were analyzed by Pearson test. Results In the Normal group and the Sham group, the renal tubular epithelial cells were regular and intact, and no interstitial inflammatory cell infiltration was observed; the renal injury score was both 1.30±0.48; immunohistochemistry showed a large amount of c-FLIP positive expression in renal tubular epithelial cells (IA: 120.20±3.87, 116.70±3.46); Western Blot showed high expression of c-FLIP in renal tissues (c-FLIP/GAPDH: 0.99±0.01, 0.98±0.02), and low expressions of Bax and caspase-3 (Bax/GAPDH: 0.16±0.04, 0.19±0.03, caspase-3/GAPDH: 0.24±0.04, 0.23±0.05). Compared with the Sham group, in the SAKI group, renal tubular epithelial cells were degenerated and necrosis, and a large number of interstitial inflammatory cells infiltrated, the renal injury score was significantly increased (4.60±0.52 vs. 1.30±0.48, P < 0.01); the levels of SCr and BUN were significantly increased [SCr (μmol/L): 193.90±13.54 vs. 24.50±3.78, BUN (mmol/L): 81.60±7.26 vs. 5.20±0.92, both P < 0.01]; the c-FLIP positive cells in renal tissues was significantly reduced (IA: 17.11±0.82 vs. 116.70±3.46, P < 0.01); the expression of c-FLIP protein in renal tissues was significantly decreased (c-FLIP/GAPDH: 0.29±0.03 vs. 0.98±0.02, P < 0.01), while the expressions of Bax and caspase-3 protein were significantly increased (Bax/GAPDH: 0.87±0.06 vs. 0.19±0.03, caspase-3/GAPDH: 0.88±0.07 vs. 0.23±0.05, both P < 0.01]. The correlation analysis showed that the c-FLIP protein was significantly negatively correlated with Bax (r = -0.468, P = 0.029) and caspase-3 protein expressions (r = -0.663, P = 0.004). Conclusions The expression level of c-FLIP protein was significantly down-regulated in renal tissue of SAKI, and its down-regulation mechanism was associated with increased apoptosis of renal tubular epithelial cells, which could be an effective target for the treatment of SAKI.