The Mechanism Research Of Sirt1/NF-κB Signaling Pathway In LPS-induced Acute Lung Injury In Rats

Objective:To investigate the role of Sirt1/NF-κBp65 signaling pathway in LPS-induced acute lung injury in rats.Method:96 healthy SD rats（160-180 g）were selected and fed in cages in a clean,constant temperature and humidity environment and the rats were fasting for 12 h before experiment.Four groups were randomly divided into four groups（n=24）:control group（group C）,acute lung injury group（ALI group）,acute lung injury+SRT1720 group（ALI+SRT1720 group）,acute lung injury+Ex527 group（ALI+Ex527 group）.Rats in ALI group received LPS with a concentration of 5mg/kg and a volume of 0.5 ml via caudal vein to prepare acute lung injury model.Rats in group ALI+SRT1720 received LPS with a concentration of 5 mg/kg and a volume of 0.5 ml via caudal vein to prepare acute lung injury model.Rats in group ALI+Ex527 received LPS with a concentration of 5 mg/kg and a volume of 0.5 ml via caudal vein to prepare acute lung injury model.Ex527 was injected into tail vein after lung injury model.At 12,24 and 48 hours after the establishment of the model,the arterial blood was collected for blood gas analysis,the wet/dry weight ratio（W/D）of lung was measured,the pathological changes of lung tissue were observed by HE staining,and the expressions of Sirt1,NF-κBp65,IL-6 and IL-1βin rat lung tissue were determined by Western blot.The expression of Sirt1 and NF-κBp65 in lung tissue was detected by RT-PCR.Results:1.There was no significant change in C group after intervention.ALI group,ALI+SRT1720 group and ALI+Ex527 group all showed varying degrees of mental depression,no appetite for food,erect hair,thin stool,some rats had hemorrhagic lumps around the eyes,head drooping nearly comatose.2.At 12 h of grouping,no rats died in C group.The survival rates of ALI group,ALI+SRT1720 group and ALI+Ex527 group were lower than those of C group（P<0.05）.At 24 h,36 h and 48 h,no rats died in C group.The survival rates of ALI group,ALI+SRT1720 group and ALI+Ex527 group were lower than those of group C.The survival rates of ALI group and ALI+Ex527 group were lower than those of ALI+SRT1720 group（P<0.05）.3.Blood gas analysis showed that the pH and PaCO₂ of ALI group,ALI+SRT1720group and ALI+Ex527 group decreased significantly at each time point,while PaCO₂increased（P<0.05）.Compared with ALI group and ALI+Ex527 group,there were significant differences in pH,PaO₂ and PaCO₂ at different time points in ALI+SRT1720 group（P<0.05）.4.W/D analysis showed that the W/D values of rats in ALI group,ALI+SRT1720group and ALI+EX527group were higher than those in C group（P<0.05）.The W/D value of lung in ALI group and ALI+EX527 group was significantly higher than that in ALI+SRT1720 group（P<0.05）.5.Histopathological analysis showed that 48 h after grouping treatment,the lung tissue structure of C group was intact,and no obvious inflammatory pathological changes were observed.The lungs of ALI group and ALI+EX527 group were obviously turbid and swollen.A large number of inflammatory cells,hemorrhage and edema were observed.The alveolar structure of ALI+SRT 1720 group was relatively uniform and intact,and the inflammatory cell infiltration was mild.6.After grouping intervention treatment,the levels of Sirt1 protein and mRNA in lung tissues of ALI group and ALI+EX527 group were down-regulated,and the levels of NF-κBp65 protein and mRNA were up-regulated（P<0.05）;compared with ALI+EX527 group,the levels of Sirt1 protein and mRNA in lung tissues of ALI+SRT1720 group were increased,while the levels of NF-κBp65 protein and mRNA in lung tissues of ALI+SRT1720 group were down-regulated（P<0.05）.7.IL-6 and IL-1βin lung tissue of rats in ALI,ALI+SRT1720 and ALI+EX527groups were significantly higher than those in C group（P<0.05）.The expression of IL-6 and IL-1βin ALI group and ALI+EX527 group was significantly higher than that in ALI+SRT1720 group（P<0.05）.8.Compared with C group,TNF-a in lung lavage fluid of rats in ALI,ALI+SRT1720and ALI+EX 527 groups increased significantly（P<0.05）.The levels of TNF-a inalveolar lavage fluid in ALI group and ALI+EX527 group were significantly higher than those in ALI+SRT1720 group（P<0.05）.Conclusion:1.LPS-induced acute lung injury can down-regulate the expression of Sirt1 and up-regulate the expression of NF-κB.2.LPS-induced acute lung injury is associated with inflammatory response regulated by Sirt1/NF-κB signaling pathway.