Study On PI3K/Akt Pathway And Related Effects In Mice With Acute Lung Injury

Objective: To investigate the mechanism of endothelial glycocalyx disruption by neutrophil elastase and the role of phosphatidylinositol PI3K/Akt in neutrophil elastase inhibitors to attenuate endotoxin ALI in mice.Methods: Thirty SPF-grade male C57BL/6 mice,6 to 8 weeks old,were randomly divided into three groups(n=10): normal saline control group(group NS),endotoxin lung injury group(group LPS),anti-inflammatory drug treatment group(group LPS+SV).Acute lung injury model was set up by tracheal drip lipopolysaccharide(LPS).Sivelestat sodium group was intraperitoneally injected with neutrophil elastase inhibitor sivelestat sodium at 3,6,9 and 12 hours after endotracheal instillation of LPS.Equivalent volume of saline drip in the airway of NS group.Alveolar lavage was given at24 h after LPS administration,and the protein concentration of alveolar lavage fluid was determined(by the BCA method);Lung tissue specimens were taken and observed under light microscopy for histopathological findings by HE staining,and the lung lobes were weighed and the lung wet-to-dry weight ratio(W/D)was calculated;FITC-dextran was infused into the trachea 1 hour before sampling,and the concentration of FITC-dextran in blood was determined(by fluorescence detection).The expression levels of Ang-2,HPSE,SDC1,PI3 K,Akt and p-Akt were measured(by Western blot).Results:1.General condition of mice after modeling: mice in group NS could drink and eat normally;The group LPS showed shortness of breath,nasal scratching,reduced drinking and eating,and reduced activity.2.Compared with group NS,bronchoalveolar lavage fluid protein concentration,W/D ratio,lung injury score,neutrophil score and FITC-dextran concentration increased in group ALI and group ALI+SV.Ang-2,HPSE,PI3 K and p-Akt expression were increased and SDC1 expression was decreased in lung tissues.3.Compared with group LPS,the protein concentration of bronchoalveolar lavage fluid,W/D ratio,lung injury score,neutrophil score and FITC-dextran concentration decreased,the expression of Ang-2,HPSE,PI3 K and p-Akt/Akt in lung tissue decreased,while the expression of SDC1 increased in group LPS+SV.Conclusions:1.For acute lung injury in mice,it can reduce the release of Ang-2 and down-regulate the expression of HPSE by inhibiting the activity of neutrophil elastase,thereby protecting the endothelial glycocalyx and improving the permeability of endotoxin-induced lung injury,and ultimately alleviating lung injury.2.Neutrophil elastase inhibitors have been shown to reduce endotoxin lung injury by inhibiting PI3K/Akt signaling pathway.