Dimethyl Fumarate Ameliorates Lipopolysaccharide-induced Acute Lung Injury And Its Mechanism

Object:Acute lung injury(ALI)is a common sudden disease in the hospital respiratory department.It is characterized by accumulation and infiltration of a large number of inflammatory cells into the lungs,extensive destruction of the alveolar membrane,release of inflammatoryrelated substances,pulmonary edema accompanied by protein exudation and deterioration of gas exchange,which eventually leads to respiratory failure.Although scientists have conducted extensive research under new treatment strategies in recent years and made some positive progress in clinical treatment,the overall performance of clinical treatment is not satisfactory.Therefore,the current treatments of ALI still need to find and excavate drugs with high safety and ideal therapeutic effects.A large number of studies have found that dimethyl fumarate(DMF)has a good therapeutic effect on a variety of lung diseases,but there is no research report on the treatment of ALI.This study aims to explore the therapeutic effects and mechanisms of DMF on ALI.Methods:(1)H&E staining:To observe the damage of lipopolysaccharide(LPS)on lung tissue of mice and establish ALI model;To observe the therapeutic effect of DMF on LPS-induced ALI in mice.(2)BCA assay:bronchoalveolar lavage fluid(BALF)was collected and its protein content was detected to reflect the degree of pulmonary edema.(3)Wright-Giemsa staining:The total number of cells were counted in BALF of mice,and then stained to observe and count neutrophils and macrophages.(4)ELISA assay:The levels of IL-1β,IL-18,IL-6 and TNFa in the BALF were detected to reflect the degree of lung inflammation.(5)Western blot:By detecting the protein expression of inflammation and oxidative stress-related pathways,the therapeutic mechanisms of DMF in improving LPS-induced ALI was explored.(6)MTT assay:BEAS-2B cells were stimulated by different concentrations of LPS or DMF,and the optimal modeling concentration and treatment concentration were selected.(7)Caspase-1 activity assay:To detect the effect of DMF to detect the effect of DMF on the pyroptosis of BEAS-2B cells stimulated by ATP plus LPS.(8)Real-time Quantitative polymerase chain reaction assay:To detect the effects of DMF on Nrf2,HO-1 and NQO1 mRNA expression in BEAS2B cells stimulated by ATP plus LPS.(9)Flow cytometry:To detect the effect of DMF on the production of reactive oxygen species(ROS)in BEAS-2B cells stimulated by ATP plus LPS.Result:(1)Compared with the control group,the lung tissues of mice in LPS group had severe pathologically damaged and lung edema,the total number of cells,neutrophils and macrophages number in BALF were markedly increased,as well as IL-1β,IL-18,IL-6,TNF-α levels were significantly increased,and the expression of lung tissue-related inflammatory proteins was significantly increased.Compared with the LPS group,the DMF group significantly improved the lung tissues pathological damage and pulmonary edema,the number of neutrophils and macrophages,as well as the levels of IL-1β,IL-18,IL-6 and TNF-α in BALF were significantly decreased,and the expression of related inflammatory proteins in lung tissues significantly decreased.(2)DMF can significantly improve the survival rate of BEAS-2B cells induced by ATP plus LPS,and reduce the levels of IL-1β,IL-18,IL-6,TNF-α,pyroptosis,ROS production and related inflammatory proteins.increased the transcription and translation of antioxidant genes.(3)The therapeutic mechanism of DMF was explored through brusatol(the Nrf2 inhibitor,BT).The experimental results showed that BT re-induced oxidative stress and inflammatory response by inhibiting the expression of Nrf2,and effectively inhibited the therapeutic effects of DMF on LPS-induced ALI.Conclusion:DMF ameliorates LPS-induced ALI by inhibiting NLRP3 inflammasome-mediated pyroptosis through enhancing Nrf2 signaling.