The Effect And Mechanism Of The MicroRNA-27a In Sepsis-induced Acute Lung Injury

ObjectiveTo investigate the expression and role of miR-27 a in sepsis-induced acute lung injury and its correlation with inflammatory factors TNF-α and IL-1 β,and its mechanism.Methods1.The rat models of sepsis were established.Forty SD male rats were randomly divided into five groups:control group,10mg/kg LPS intraperitoneally injected 3,6,12,24 h groups.The injury of lung tissues were evaluated by lung wet/dry weight ratio and histopathology,qRT-PCR was used to assay the expressions of miR-27 a in lungs,ELISA was used to detect the concentrations of TNF-α and IL-1β in lungs.2.The sepsis model of A549 cells were established.The A549 cells were divided into five groups:control group,10μg/mL LPS stimulated3,6,12,24 h groups.qRT-PCR was used to assay the expressions of miR-27 a in cells,ELISA was used to detect the concentrations of TNF-α and IL-1βin the supernatant,Western Blot was used to detect the protein expressionsof p-AKT and p-mTOR in cells.3.The A549 cells were transfected with miR-27 a inhibitor and 24 hours later were treated with 10μg/mL LPS,after 24 hours qRT-PCR was used to assay the expressions of miR-27 a in cells,ELISA was used to detect the concentrations of TNF-α and IL-1β in the supernatant,Western Blot was used to detect the protein expressions of p-AKT and p-mTOR in cells.Results1.Data showed that W/D ratio of lung tissues in sepsis groups are significantly higher than that in control group.The lung tissue hematoxylin-eosin staining indicated that the structure of lung tissues was destroyed,there were incomplete alveolar expansion,alveolar fusion or collapse,the alveolar septa were thickened,the alveolar cavity were filled with pink edema,interstitial inflammatory cell infiltration and hemorrhage were observed in sepsis groups.2.The expressions of miR-27 a and inflammatory factors TNF-α and IL-1β in lung tissues of septic rats and their correlations.The expressions of miR-27 a were higher in sepsis groups than that in control group at any time in lungs,the concentrations of TNF-α and IL-1β were higher in sepsis groups than those in control group at any time in lungs,The expressions of miR-27 a showed positive correlation with those of TNF-α and IL-1β.3.The expressions of miR-27 a and inflammatory factors TNF-α and IL-1β in LPS-stimulated A549 cells and their correlations.The expressionsof miR-27 a were higher in sepsis groups than that in control group at any time in cells,the concentrations of TNF-α and IL-1β were higher in sepsis groups than those in control group at any time in the supernatant,The expressions of miR-27 a showed positive correlation with those of TNF-αand IL-1β.4.The protein expressions of p-AKT and p-mTOR in LPS-stimulated A549 cells.The protein expressions of p-AKT and p-mTOR were higher in sepsis groups than those in control group at any time in A549 cells,along with the extension of time of stimulation,the protein expressions of p-AKT and p-mTOR gradually increased.5.Effects of transfection of miR-27 a inhibitor on the concentrations of inflammatory factors TNF-α,IL-1β and the protein expressions of p-AKT and p-mTOR in A549 cells.miR-27 a inhibitor significantly decreased the concentrations of TNF-α and IL-1β and the protein expressions of p-AKT and p-mTOR in sepsis-induced acute lung injury.ConclusionMiR-27 a can attenuates sepsis-induced acute lung injury by inhibiting signal transduction of AKT/mTOR,which provides a new target for sepsis-induced acute lung injury diagnosis and treatment.