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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.
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Objective:To evaluate protective effects of SS31 on early brain injury (EBI) induced by subarachnoid hemorrhage (SAH) in rats.Methods:A total of 96 Sprague-Dawley rats were randomly divided into 4 groups:A sham group,an SAH group,an SAH+vehicle group (SAH+V),and an SAH+SS31 group.The SAHinduced prechiasmatic cistern rat model was established in this study.Neurological deficit scores were evaluated at 24 h after SAH.The SS31 (5 mg/kg) as well as equal volume of vehicle were administrated intraperitoneally at 2 h after SAH.The neurological scores,brain edema,blood-brain barrier (BBB) permeability,apoptosis,malondialdehyde (MDA),glutathione peroxidase (GPx) activity,superoride dismutase (SOD) activity,and the expression ofcytosolic cytochrome c (Cyt C) and Bax were analyzed at 24 h after SAH.Results:Treatment with SS31 could significantly reduce MDA levels,and restored the activities of GPx and SOD in the cortex following SAH when compared with the SAH+V group.In addition,Bax SS31 trearment increased or decreased the levels of mitochondrial Cyt C or Bax,respectively.Moreover,SS31 treatment ameliorated brain edema and Evans blue dye extravasation,improved neurological deficits,and decreased neuronal apoptosis at 24 h after SAH.Conclusion:SS31 could alleviate EBI after SAH through its antioxidant property and ability in inhibition of neuronal apoptosis.
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Objective To investigate the effects of antioxidant SS-31 on sepsis-induced acute lung injury (ALI)in a mouse model of sepsis.Methods Sepsis was induced in male mice by cecal liga-tion and puncture (CLP).Forty-eight adult male mice (C57BL/6,weight 25-32 g)were equally as-signed to the sham+vehicle group (group A),sham+SS-31 group (group B),CLP+vehicle group (group C),or the CLP+SS-31 group (group D).At 0 or 5 h after CLP or sham operation,mice re-ceived an intraperitoneal injection of SS-31 (5 mg/kg of body weight)or the same volume of normal saline.Pulmonary tumor necrosis factor alpha (TNF-α),interleukin (IL)-6,IL-10,malondialdehyde (MDA),superoxide dismutase activities (SOD),myeloperoxidase activities (MPO ),wet-to-dry weight ratio (W/D),reactive oxygen species (ROS),ATP,NF-κB p65,inducible nitric oxide syn-thase (iNOS),and histological scores were assessed 24 h after operation.Results Pneumonia,edema were significantly heavier in group C than in group A (P <0.05).Lung congestion,inflammatory cell infiltration,alveolar wall edema was significantly less in group D than in group C (P <0.05).Pulmo-nary histological scores,IL-6,MDA,MPO,W/D,ROS,NF-κB p65 and iNOS significantly in-creased,while ATP levels decreased in group C when compared with group A (P <0.05).However, SS-31 treatment significantly reversed these parameters when compared with the group C (P <0.05). No difference was observed between the group A and group B.There was no difference of TNF-α,IL-10,and SOD among the four groups.Conclusion SS-31 improves sepsis-induced ALI in a mouse model probably by down-regulating the oxidative stress and inflammation in of sepsis-induced ALI.
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Background Presbyopia is one of primary causes affecting the visual and life qualities of the agings,and its mechanism is associated with the oxidative damage of lens epithelial cells with ageing.SS31 is a mitochondria-targeted antioxidant peptide.To study the effect of SS31 on oxidative damage of lens epithelial cells has an important significance for the prevention and treatment of presbyopia.Objective This study was to investigate the effect of SS31 on in vitro oxidative damaged human lens epithelial cells.Methods Human lens epithelial cell line (HLEB-3) was cultured using DMEM with low glucose and 10％ fetal bovine serum(FBS).The cell model of oxidative damage was established by adding 200 μmol/L tea-butyl hydropeoxide (t-BHP) into DMEM for 18 hours.The cells were divided into blank control group,t-BHP model group,10 nmol/L SS31 +t-BHP group,100 nmol/L SS31 +t-BHP group,1 μmol/L SS31 +t-BHP group,10 μmol/L SS31 +t-BHP group and 100 pμmol/L t-BHP group,and then MTT assay was used to detect the survival rate of the cells and evaluate the optimal SS31 concentration for sequential study.The cells then were divided into blank control group,t-BHP model group and 1 μmol/L SS31 +t-BHP co-culture group.The change of mitochondrial membrane potential of the cells was tested by JC-1 dye and flow cytometry.Reactive oxygen species (ROS) level in the mitochondria was determined using MitoSOX staining.Results The cell survival rate in the t-BHP model group was (53.42±2.52)％,and that in the blank control group was 100％.The cell survival rate was considerably increased in various concentrations of SS31 groups,showing a significant difference among different groups (F=58.349,P＜0.01).A highest survival rate was (82.13 ±3.15) ％ in the 1 μmol/L SS31 +t-BHP co-culture group,which was statistically significant in comparison with the t-BHP model group (t =28.710,P＜0.05).JC-1 dye and flow cytometry assay showed that the ratio between red and green fluorescence intensity was 7.07 ±0.06 in the blank control group,4.46±0.14 in the t-BHP model group and 5.76±0.26 in the 1 μmol/L SS31 +tBHP co-culture group,showing significant difference among the 3 groups (F=172.332,P＜0.01).The ratios between red and green fluorescence intensity in the blank control group and 1 μmol/L SS31 +t-BHP co-culture group were higher than that in the t-BHP model (t =2.609,1.303,both at P＜0.001).ROS fluorescence cells were much more in the t-BHP model group compared with blank control group and 1 μmol/L SS31 + t-BHP co-culture group.Conclusions SS31 can protect HLEB-3 cells from oxidative stress.SS31 may serve as a potential new approach to the treatment of presbyopia and other age-related diseases of lens.