| Objective: To investigate the protective effect of high-dose vitamin C on sepsis mice and its relationship with caspase and miR126a-5p,a model of acute lung injury induced by cecal puncture and ligation was used to provide a new target and a new direction for clinical treatment.Methods: Four to six weeks of healthy male BALB/c mice were anesthetised with5% chloral hydrate solution,and the limbs were fixed and then cecal puncture and ligation(CLP),a classical method,was used to model sepsis and induce septic acute lung injury in healthy mice.The experiment was divided into three groups:The rats were divided into sham operation group(control group,CON group),sepsis +NS group(model group,SEP group),sepsis +Vitamin C group(drug intervention group,SEP +IR group).Before cecal puncture and ligation induced sepsis acute lung injury,1000mg/kg Vitamin C injection was injected into tail vein for 3 consecutive days.The sham operation group and the sepsis+Vitamin C group were injected with the same volume of normal saline for 3 consecutive days.12 h after sepsis model induced acute lung injury,lung tissue in sepsis with acute lung injury(only with filter paper blot untreated lung tissue and dry after 48 h)for weighing,calculating the ratio of lung wet weight/dry weight,the hematoxylin-eosin(H&E staining),lung tissue staining,detection of mice lung tissue pathological changes,The levels of inflammatory factors(IL-6,TNF-α)in lung tissues were determined by ELISA method.Caspase-1 and Caspase-3 in lung tissues with septic lung injury were determined by Western blot method.Mir126a-5p in lung tissues with septic lung injury was determined by fluorescence quantitative PCR methods.Results:1.Effect of high dose vitamin C pretreatment on survival rate of mice with septic lung injury after cecal puncture and ligation.After caecal puncture and ligation,healthy mice showed lethargy,erection of hair,poor mental state,black stool,etc.24 h after caecal puncture and ligation,the survival rate of control group,model group and drug intervention group was 100%,0,33%,and the survival rate of the caecal vein injection of vitamin C(1000mg/kg)was significantly higher than that of the model group.The results indicate that high dose of vitamin C can reduce the inflammation of sepsis lung injury and improve the survival rate.Effect of high dose vitamin C pretreatment on lung wet/dry weight(W/D)ratio in acute lung injury mice undergoing cecal puncture and ligation of septic lung injury.The wet-dry weight ratio of the model group with cecal puncture and ligation was significantly higher than that of the control group(P < 0.05).2.Effect of high dose vitamin C pretreatment on pathological sections of lung tissue in mice with acute lung injury caused by sepsis.The control group(sham operation group)had complete alveolar structure without obvious inflammatory cell infiltration,and no obvious thickening of alveolar wall was observed.The model group of caecal puncture and ligation had no complete alveolar structure,and alveolar wall congestion and edema,with obvious inflammatory cell infiltration and obvious thickening,while the changes of lung tissue of acute lung injury after the tail vein injection of high dose vitamin C were between the two.3.Effect of high dose vitamin C pretreatment on the expression of pro-inflammatory factors IL-6 and TNF-α in lung tissue inflammatory factors of mice with acute lung injury caused by sepsis.The contents of IL-6 and TNF-α in the model group of cecal puncture and ligation were significantly higher than those in the control group(P < 0.05),and the contents of IL-6 and TNF-α in the highdose vitamin C pretreatment group were significantly lower than those in the control group.4.Effects of high-dose vitamin C pretreatment on the levels of Caspase-1 and Caspase-3 proteins in lung tissues of mice with acute lung injury caused by sepsis.The expression of Caspase-1 and Caspase-3 protein levels in the lung tissues of mice was detected,and the results showed that the expression of Caspase-1 and Caspase-3 in the caecal puncture and ligation model group was significantly higher than that in the control group,i.e.the sham operation group(P < 0.05).After pretreatment,the expression of Caspase-1 and Caspase-3 in high dose vitamin C was significantly lower.5.Effect of high dose vitamin C pretreatment on the expression of miR126a-5p in the lung tissue of acute lung injury caused by sepsis.The detection of miR126a-5p in the lung tissue of mice showed that the miR126a-5p in the model group after cecal puncture and ligation was significantly higher than that in the control group and the sham group.Compared with the model group,the miR126a-5p in the high vitamin C preconditioning was significantly lower than that in the model group.Conclusion: Pretreatment with high dose of vitamin C may be related to the survival of sepsis mice with acute lung injury.High dose of vitamin C preconditioning reduced inflammation in sepsis mice with acute lung injury,which may be related to the decrease of wet/dry weight ratio in the treatment group,and may be related to the change of alveolar diameter.Lung protection after acute lung injury induced by sepsis pretreated with high dose of vitamin C may be related to the mechanism by which miR126a-5p reduces the expression of caspase-1 and caspase-3 proteins.Further studies can provide new targets for the treatment of septic lung injury. |
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