The Protective Mechanism Of Quercetin Against Acute Lung Injury Induced By LPS In Mice

Objective:(1)In vivo experiments confirmed the protective effect of quercetin on acute lung injury induced by LPS-induced sepsis in mice,and explored the biological application prospect of quercetin in acute inflammatory response.(2)In vitro experiments were conducted to clarify the inhibitory effect of quercetin on LPS+ATP-induced pyroptosis,to clarify the correlation between pyroptosis and changes in cell metabolism,and to explore whether quercetin exerts anti-inflammatory effects by affecting cell metabolism.Methods: The first is the preparation and grouping of animal models.Wild-type C57BL/6 mice were selected as the research objects,half male and female,and divided into 4 groups: control group,LPS group,Que group,and LPS+Que group,with 10 mice in each group.LPS(20 mg/kg)was injected intraperitoneally to establish a mouse model of acute lung injury caused by exogenous factors in the lung.The LPS+Que group was intraperitoneally injected with Que(50 mg/kg)2 hours before LPS treatment,and the control group was intraperitoneally injected with an equal dose of PBS.Mice were euthanized 18 hours after LPS treatment and mouse plasma and bilateral lung tissue samples were collected.Lung tissue was stained with hematoxylin and eosin to observe the pathological changes of lung tissue.The ipsilateral lung was collected and dried in an oven at 80 °C for 72 hours to calculate the lung dry-wet ratio of mice in each group.Lipid peroxidation MDA detection kit was used to measure the content of MDA in lung tissue,and the levels of TNFα,IL-1β,and IL-6 in plasma and lung tissue in each group were detected by ELISA method to evaluate the degree of lung tissue or systemic inflammation.The expression levels of NLRP3,Caspase-1,SIRT1,PKM2 and other genes or proteins in lung tissue samples were detected by q PCR and Western blot.Then use LPS+ATP to induce pyroptosis,explore the expression of PKM2 when SIRT1 is overexpressed or inhibited,and study the mechanism of Que how to exert anti-inflammation effects.The expression levels of NLRP3,Caspase-1,SIRT1,PKM2 and other genes or proteins in cell samples were detected by q PCR and Western blot.Results: HE staining showed that Que could significantly reduce the inflammatory cell infiltration,alveolar congestion,swelling and other pathological changes in lung tissue caused by LPS-induced acute lung injury.Quantitative analysis of ELISA,q PCR,Western blot,etc.in lung tissue and cells showed that Que can significantly increase the expression of SIRT1,inhibit the expression of PKM2 in the nucleus,inhibit the classical inflammasome NLRP3 in the pyroptotic pathway,and activate Caspase-1 and related inflammation cytokines such as TNFα,IL-6,IL-1β,IL-18.Conclusion: Que has a good protective effect on LPS-induced ALI.Que can significantly increase the expression of SIRT1,inhibit the nuclear expression of PKM2,a key enzyme of glycolytic metabolism,and inhibit expression of lung and systemic inflammatory factors such as TNFα,IL-6,IL-1β,IL-18,etc.and finally play an anti-inflammatory effect by inhibiting the pyroptotic pathway to relieve LPS-induced pulmonary acute inflammatory response.Additionally,SIRT1 is closely related to PKM2.PKM2 can be regulated by SIRT1 as a downstream target and affect its intracellular sub-localization.High expression of SIRT1 can reduce the nuclear expression of PKM2,thereby inhibiting LPS-induced pyroptosis and related inflammatory responses.