Exploring the Protective Effect of Modified Taoren Chengqi Decoction on Ventilator-induced Lung Injury in Rats Based on the Nrf2/GPX4-ferroptosis Pathway
Objective To explore the protective effect of modified Taoren Chengqi Decoction on ventilator-induced lung injury(VILI)in rats based on the nuclear factor-erythroid 2-related factor 2(Nrf2)/glutathione peroxidase 4(GPX4)-ferroptosis pathway.Methods Rats were randomly separated into the control group,the model group,the modified Taoren Chengqi Decoction group,the ML385(Nrf2 inhibitor)group,and the modified Taoren Chengqi Decoction+ML385 group,with 12 rats in each group.The rats in control group underwent tracheal intubation and kept spontaneous breathing.The rats of other groups were subjected to mechanical ventilation for 4 hours.Seven days before mechanical ventilation,medication treatment was carried out once a day for seven days.After mechanical ventilation,ELISA was applied to detect the levels of tumor necrosis factor-α(TNF-α)and interleukin 6(IL-6)in bronchoalveolar lavage fluid(BALF).Lung wet/dry weight ratio and lung tissue pathology of rat were detected.The reagent kit was applied to detect the content of glutathione(GSH),malonaldehyde(MDA),and Fe2+in rat lung tissue.The relative fluorescence intensity of reactive oxygen species(ROS)and 4-hydroxynonenal(4-HNE)in lung tissue was detected by immunofluorescence staining.The mRNA and protein expressions of solute carrier family 7 member 11(SLC7A11),Nrf2,GPX4 were detected.Results Compared with the control group,the lung tissue of rats in model group was severely damaged,the levels of TNF-α and IL-6 in BALF increased,lung wet/dry weight ratio,content of MDA and Fe2+,and the relative fluorescence intensity of ROS and 4-HNE increased,but the content of GSH,the mRNA and protein expressions of Nrf2,SLC7A11,and GPX4 decreased(P<0.01).Compared with the model group,the pathological damage of lung tissue in the modified Taoren Chengqi Decoction group was improved,the levels of TNF-α and IL-6 in BALF decreased,lung wet/dry weight ratio,content of MDA and Fe2+,the relative fluorescence intensity of ROS and 4-HNE decreased,the content of GSH,the mRNA and protein expressions of Nrf2,SLC7A11,and GPX4 increased(P<0.01).However,an opposite trend for corresponding indicators in the ML385 group was found(P<0.01).The pathological injury of lung tissue was alleviated,the levels of TNF-α and IL-6 in BALF decreased,lung wet/dry weight ratio,content of MDA and Fe2+,and the relative fluorescence intensity of ROS and 4-HNE decreased,GSH content,the mRNA expression of Nrf2,SLC7A11 and GPX4,as well as the protein expression of Nrf2 and GPX4 increased in modified Taoren Chengqi Decoction+ML385 group(P<0.01,P<0.05).Compared with ML385 group,the pathological injury of lung tissue was alleviated,the levels of TNF-α and IL-6 in BALF decreased,lung wet/dry weight ratio,the content of MDA and Fe2+,and the relative fluorescence intensity of ROS and 4-HNE decreased,GSH content,the mRNA and protein expression of Nrf2,SLC7A11 and GPX4 increased in modified Taoren Chengqi Decoction+ML385 group(P<0.01).Compared with the modified Taoren Chengqi Decoction group,the pathological damage in lung tissue of rats was intensified,the levels of TNF-α and IL-6 in BALF increased,lung wet/dry weight ratio,the content of MDA and Fe2+,the relative fluorescence intensity of ROS and 4-HNE increased,the content of GSH,the mRNA and protein expressions of Nrf2,SLC7A11,and GPX4 decreased(P<0.01)in modified Taoren Chengqi Decoction+ML385 group.Conclusion Modified Taoren Chengqi Decoction may improve rat VILI by activating the Nrf2/GPX4 pathway to inhibit ferroptosis.