Study On The Mechanism Of Propofol Reducing Ventilator-related Lung Injury By Regulating The Nrf2/NLRP3 Signaling Pathway

Backgrounds and goalAcute lung injury(ALI)is an acute inflammatory disease characterized by impaired vascular integrity but increased permeability of the epithelium and endothelium.Patients with ALI experience mechanical ventilation,which usually results in lung injury induced by the ventilator.Studies have shown that the activation of macrophages may be one of the factors in the pathogenesis of VILI,and the imbalance of pro-inflammatory and anti-inflammatory factors is the main cause of VILI.In addition,a target for inhibiting the generation of reactive oxygen species(ROS)has also been proposed to prevent VILI.Therefore,the specific mechanism of anti-inflammatory and anti-ROS drugs and genes in VILI may be the therapeutic target of VILI.Propofol is an anesthetic that inhibits neuronal death and can activate the activity of type A gamma-aminobutyric acid receptors and improve ALI.Nuclear factor E2-related factor 2(Nrf2)is a member of nuclear receptors.As a transcription factor,it can be activated by oxidative stress.In addition,it has been found that propofol can activate Nrf2 and improve ALI in rats undergoing liver transplantation.However,the role of propofol and Nrf2 in VILI is rarely discussed.Interestingly,it is reported that the interaction between Nrf2 and NOD-like receptor protein 3(NLRP3)inflammasome has anti-inflammatory and antioxidant functions.It was also found that NLRP3 mediated by propofol can improve inflammation and reduce brain damage.Therefore,we propose that propofol may reduce ventilator-related lung injury by regulating the Nrf2/NLRP3 signaling pathway,and provide a clinical theory for the prevention of VILI.Methods126 healthy adult male C57BL/6 mice aged 8-12 weeks,weighing about 20-25 grams,were provided by the Experimental Animal Center of Shanghai Second Military Medical University.Randomly divided into 9 groups,each with 14 animals:(1)sham operation group;(2)normal tidal volume group(VT:7mL/kg);(3)high tidal volume group(VT:20mL/kg);(4)Mechanical ventilation related lung injury+propofol group(VILI+Prop group);(5)propofol group(Prop group);(6)mechanical ventilation related lung injury+propofol+Nrf2 activator-sulforaphane(Sulforaphane)group(VILI+ Prop+SFN group);(7)Mechanical ventilation-related lung injury+propofol+Nrf2 activator SFN+NLRP3 activator-Nigericin group(VILI+Prop+SFN+Niger group(8)Mechanical ventilation-related lung injury+propofol+ Nrf2 inhibitor-All-trans retinoic acid(VILI+Prop+ATR group);(9)Mechanical ventilation-related lung injury+Propofol+Nrf2 inhibitor ATR+NLRP3 activator Niger group(VILI+Prop+ATR+Niger group).Lung tissue hematoxylin and eosin(H&E)staining was performed,and lung tissue wet/dry weight ratio(wet/dry,W/D),lung tissue EBA permeability index,bronchoalveolar perfusion were measured The protein concentration of bronchoalveolar lavage fluid(BALF),the expression levels of MDA and 8-OHdG in lung tissues,and inflammation-related myeloperoxidase(MPO)activity in lung tissues.Various inflammations in BALF were detected by ELISA Factors(MPO,IL-1?,IL-18,TNF-?,IL-6 and MIP-2)expression levels and the total number of BAL cells,BAL neutrophils and macrophages,Western analysis of NLRP3 in alveolar macrophages,ASC and caspase-1 protein expression and Nrf2 protein expression in lung tissue,RT-qPCR detection of SOD and HO-1 mRNA expression in lung tissue,and ROS rate in mitochondria.Results(1)After VILI mice were injected with propofol,their lung tissue pathological morphology was improved,and the lung tissue W/D value,EBA permeability index and protein content in BALF were significantly reduced(P<0.05).Show that propofol can improve ventilator-related lung injury.(2)After VILI mice were injected with propofol,the expression levels of various inflammatory factors(MPO,IL-1?,IL-18,TNF-?,IL-6 and MIP-2)in their BALF and 8-The levels of OHdG and MDA were significantly reduced(P<0.05).Show that propofol can alleviate lung inflammation caused by mechanical communication.(3)After VILI mice were injected with propofol,the expressions of NLRP3 protein,ASC protein,caspase-1 protein and ROS in alveolar macrophages were all decreased(P<0.05),and Nrf2 and superoxide in lung tissue Both the expression of biodismutase(SOD)and heme oxidase(HO-1)increased(P<0.05).It shows that after propofol treatment,propofol can up-regulate the expression of Nrf2 in VILI and down-regulate the expression of NLRP3.(4)After VILI mice were injected with propofol,activation of Nrf2 could significantly reduce the expression of caspase-1,IL-1? and IL-18 mRNA and corresponding proteins in the lung tissue of mice,and the inflammatory factor IL-1? in BALF And the expression level of IL-18 also decreased.The pathological morphology of lung tissue was further improved.It shows that Nrf2 can inhibit the pro-inflammatory factors in the lung tissue of VILI mice,thereby protecting lung injury.(5)After VILI mice were injected with propofol and activated Nrf2 and activated NLRP3,the mice showed severe lung tissue pathological damage.The expression of IL-1? and IL-18 in BALF and the expression of caspase-1,IL-1? and IL-1 protein level was significantly increased;on the contrary,after VILI mice were injected with propofol to inhibit Nrf2,the above-mentioned more serious pathological phenomena would occur when NLRP3 was activated.It shows that NLRP3 inhibits the protection of Nrf2 on lung injury by promoting inflammation.ConclusionIn summary,these data indicate that propofol can protect VILI and subsequent inflammation by activating Nrf2 and inhibiting the expression of NLRP3.Therefore,Nrf2 activators and NLRP3 inhibitors may be potential therapeutic drugs to prevent VILI.