Objective:To evaluate the role of peptidylarginine deiminase 4 (PAD4)-mediated development of neutrophil extracellular traps (NETs) in lung ischemia-reperfusion injury (LIRI) in mice.Methods:Ninety-six clean-grade healthy male C57BL/6 mice, aged 6-8 weeks, weighing 20-25 g, were divided into 4 groups ( n=24 each) using a table of random numbers: sham operation group (group S), sham operation + PAD4 specific inhibitor GSK484 group (group S+ G), lung ischemia-reperfusion group (group L), and lung ischemia-reperfusion + GSK484 group (group L+ G). After anesthesia and mechanical ventilation, mice were subjected to left hilum occlusion for 1 h followed by 2 h of reperfusion to establish the LIRI model in L and L+ G groups. Mice underwent thoracotomy for 3 h without left hilum occlusion in S and S+ G groups. In S+ G and L+ G groups, GSK484 4 mg/kg was intraperitoneally injected once a day for 3 days before developing the model. At the end of reperfusion, blood samples were collected from the abdominal aorta for blood gas analysis to record arterial partial pressure of oxygen (PaO 2). Mice were then sacrificed to collect bronchoalveolar lavage fluid (BALF) and to obtain lung tissues. The concentrations of interleukin (IL)-1β, IL-6, tumor necrosis factor-α (TNF-α) and myeloperoxidase (MPO) in BALF were measured using enzyme-linked immunosorbent assay. The wet/dry lung weight (W/D) ratio was calculated. The lung tissues were obtained for microscopic examination of pathological changes (with a light microscope) which were scored after hematoxylin-eosin staining and for determination of the contents of superoxide dismutase (SOD) and malondialdehyde (MDA) (by colorimetric assay) and expression of PAD4, neutrophil elastase (NE), high-mobility group box 1 (HMGB1), and citrullinated histone 3 (Cit-H3) (by Western blot). Results:Compared with group S, lung injury scores and W/D ratios were significantly increased, PaO 2 was decreased, the concentrations of IL-1β, IL-6, TNF-α and MPO in BALF were increased, the content of SOD was decreased, the content of MDA was increased, and the expression of PAD4, NE, HMGB1 and Cit-H3 was up-regulated in L and L+ G groups ( P<0.05), and no significant changes were observed in the aforementioned parameters in group S+ G ( P>0.05). Compared with group L, lung injury scores and W/D ratios were significantly decreased, PaO 2 was increased, concentrations of IL-1β, IL-6, TNF-α, and MPO in BALF were decreased, the content of SOD was increased, the content of MDA was decreased, and the expression of PAD4, NE, HMGB1 and Cit-H3 was down-regulated in group L+ G ( P<0.05). Conclusions:Up-regulated PAD4 expression can promote the development of NETs and aggravate oxidative stress and inflammatory responses in lung tissues, thereby participating in LIRI in mice.

Objective:To evaluate the role of peptidylarginine deiminase 4 (PAD4)-mediated development of neutrophil extracellular traps (NETs) in lung ischemia-reperfusion injury (LIRI) in mice.Methods:Ninety-six clean-grade healthy male C57BL/6 mice, aged 6-8 weeks, weighing 20-25 g, were divided into 4 groups ( n=24 each) using a table of random numbers: sham operation group (group S), sham operation + PAD4 specific inhibitor GSK484 group (group S+ G), lung ischemia-reperfusion group (group L), and lung ischemia-reperfusion + GSK484 group (group L+ G). After anesthesia and mechanical ventilation, mice were subjected to left hilum occlusion for 1 h followed by 2 h of reperfusion to establish the LIRI model in L and L+ G groups. Mice underwent thoracotomy for 3 h without left hilum occlusion in S and S+ G groups. In S+ G and L+ G groups, GSK484 4 mg/kg was intraperitoneally injected once a day for 3 days before developing the model. At the end of reperfusion, blood samples were collected from the abdominal aorta for blood gas analysis to record arterial partial pressure of oxygen (PaO 2). Mice were then sacrificed to collect bronchoalveolar lavage fluid (BALF) and to obtain lung tissues. The concentrations of interleukin (IL)-1β, IL-6, tumor necrosis factor-α (TNF-α) and myeloperoxidase (MPO) in BALF were measured using enzyme-linked immunosorbent assay. The wet/dry lung weight (W/D) ratio was calculated. The lung tissues were obtained for microscopic examination of pathological changes (with a light microscope) which were scored after hematoxylin-eosin staining and for determination of the contents of superoxide dismutase (SOD) and malondialdehyde (MDA) (by colorimetric assay) and expression of PAD4, neutrophil elastase (NE), high-mobility group box 1 (HMGB1), and citrullinated histone 3 (Cit-H3) (by Western blot). Results:Compared with group S, lung injury scores and W/D ratios were significantly increased, PaO 2 was decreased, the concentrations of IL-1β, IL-6, TNF-α and MPO in BALF were increased, the content of SOD was decreased, the content of MDA was increased, and the expression of PAD4, NE, HMGB1 and Cit-H3 was up-regulated in L and L+ G groups ( P<0.05), and no significant changes were observed in the aforementioned parameters in group S+ G ( P>0.05). Compared with group L, lung injury scores and W/D ratios were significantly decreased, PaO 2 was increased, concentrations of IL-1β, IL-6, TNF-α, and MPO in BALF were decreased, the content of SOD was increased, the content of MDA was decreased, and the expression of PAD4, NE, HMGB1 and Cit-H3 was down-regulated in group L+ G ( P<0.05). Conclusions:Up-regulated PAD4 expression can promote the development of NETs and aggravate oxidative stress and inflammatory responses in lung tissues, thereby participating in LIRI in mice.

Objective:To evaluate the role of Z-DNA-binding protein 1 (ZBP1)/receptor-interacting protein kinase 1 (RIPK1) signaling pathway in lipopolysaccharide (LPS)-adenosine triphosphate (ATP)-induced pyroptosis in macrophages of mice.Methods:The RAW264.7 macrophages from mice were routinely cultured and divided into 6 groups ( n=9 each) using a random number table method: control group (group C), LPS-ATP group, LPS-ATP+ transfection negative control scRNA group (group LPS-ATP+ scRNA), LPS-ATP+ ZBP1 small interference RNA group (group LPS-ATP+ siRNA), LPS-ATP+ dimethyl sulfoxide group (group LPS-ATP+ DSMO), and LPS-ATP+ RIPK1 inhibitor nec-1 group (group LPS-ATP+ nec-1). The siRNA technique was used to inhibit the expression of ZBP1 in group LPS-ATP+ siRNA. The RIPK1 inhibitor nec-1 was given to inhibit the expression of RIPK1 protein in group LPS-ATP+ nec-1. Group C was routinely cultured. Cells were incubated with 10 μg/ml LPS for 24 h, then 5 mmol/L ATP was added, and the cells were incubated for 30 min to develop the cell pyroptosis model in the remaining 5 groups. The cell survival was detected by the CCK-8 assay. The concentrations of interleukin-1beta (IL-1β), IL-6, IL-18 and tumor necrosis factor-alpha (TNF-α) in cell supernatant were determined by enzyme-linked immunosorbent assay. The pyroptosis was determined by propidium iodide fluorescence staining. Western blot was used to detect the expression of ZBP1, RIPK1, caspase-1 and GSDMD. Results:Compared with group C, the cell survival rate was significantly decreased, the cell pyroptosis rate and concentrations of IL-1β, IL-6, IL-18 and TNF-α in the supernatant were increased, and the expression of ZBP1, RIPK1, caspase-1 and GSDMD was up-regulated in group LPS-ATP ( P<0.05). Compared with group LPS-ATP, no significant change was found in the parameters mentioned above in group LPS-ATP+ scRNA and group LPS-ATP+ DSMO ( P>0.05). Compared with group LPS-ATP+ scRNA, the cell survival rate was significantly increased, the cell pyroptosis rate and concentrations of IL-1β, IL-6, IL-18 and TNF-α in the supernatant were decreased, and the expression of ZBP1, RIPK1, caspase-1 and GSDMD was down-regulated in group LPS-ATP+ siRNA ( P<0.05). Compared with group LPS-ATP+ DMSO, the cell survival rate was significantly increased, the cell pyroptosis rate and concentrations of IL-1β, IL-6, IL-18 and TNF-α in the supernatant were decreased, the expression of ZBP1, caspase-1 and GSDMD was down-regulated ( P<0.05), and no significant change was found in the expression of ZBP1 in group LPS-ATP+ nec-1 ( P>0.05). Conclusions:Activation of ZBP1/RIPK1 signaling pathway is involved in LPS-ATP-induced pyroptosis in macrophages of mice.

Objective:To evaluate the relationship between inositol-requiring enzyme 1α-X box-binding protein 1 (IRE1α-XBP1) signaling pathway in endoplasmic reticulum and neutrophil extracellular traps during endotoxin-induced acute lung injury (ALI) in mice.Methods:Forty-eight SPF healthy male C57BL/6 mice, aged 6-8 weeks, weighing 25-30 g, were divided into 4 groups ( n=12 each) using a random number table method: control group (C group), STF-083010 group (ST group), lipopolysaccharide (LPS)-induced ALI group (ALI group) and LPS-induced ALI + STF-083010 group (ALI+ ST group). The ALI model was established by inhaling aerosolized LPS in ALI group and ALI+ ST group. The equal volume of aerosolized normal saline was inhaled in C and ST groups. IRE1α inhibitor STF-083010 50 mg/kg was intraperitoneally injected at 1 h before developing the model in ST and ALI+ ST groups, and the equal volume of normal saline was intraperitoneally injected in the other two groups. The mice were sacrificed after anesthesia at 24 h after developing the model. Bronchoalveolar lavage fluid (BALF) and lung tissues were collected for determination of the pathological changes (by light microscopy) which were scored, wet/dry lung weight (W/D) ratio, concentrations of interleukin-1beta (IL-1β), IL-18 and myeloperoxidase (MPO) in the BALF supernatant, and expression of phosphorylated IRE1α(p-IRE1α), XBP1s and citrullinated histone H3 (Cit H3) in lung tissues (using Western blot). Results:Compared to group C, the lung injury scores and W/D ratio were significantly increased at 24 h after developing the model, the concentrations of IL-1β, IL-18 and MPO in BALF were increased, and the expression of p-IRE1α, XBP1s and Cit H3 in lung tissues was up-regulated in ALI and ALI+ ST groups. Compared to group L, the lung injury scores and W/D ratio were significantly decreased at 24 h after developing the model, the concentrations of IL-1β, IL-18 and MPO in BALF were decreased, and the expression of p-IRE1α, XBP1s and Cit H3 in lung tissues was down-regulated in group ALT+ ST ( P<0.05). Conclusions:The IRE1α-XBP1 signaling pathway in endoplasmic reticulum is involved in endotoxin-induced ALI by up-regulating the expression of neutrophil extracellular traps in mice.

Objective:To evaluate the role of heat shock transcription factor 1 (HSF1) in the endogenous protective mechanism underlying mechanical ventilator-induced lung injury (VILI) in mice and the relationship with high mobility group box 1 (HMGB1).Methods:Forty SPF healthy male C57BL/6 mice, aged 6-8 weeks, weighing 20-25 g, were divided into 4 groups ( n=10 each) by the random number table method: control group (group C), VILI group (group VILI), negative control siRNA + VILI group (group NV) and HSF1 siRNA + VILI group (group siRNA). At 48 h before mechanical ventilation, negative control siRNA 5 nmol and HSF1 siRNA 5 nmol were intratracheally injected in NV and siRNA groups respectively, and the solution was diluted to 50 μl with the sterile phosphate buffer in both groups. Group C kept spontaneous breathing for 4 h, and the rest animals were mechanically ventilated (tidal volume 35 ml/kg, respiratory rate 75 breaths/min, inspiratory/expiratory ratio 1∶2, fraction of inspired oxygen 21%) for 4 h. Blood samples from the femoral artery were collected for arterial blood gas analysis immediately after endotracheal intubation and at 4 h of ventilation, and PaO 2 was recorded. Then the mice were sacrificed under deep anesthesia to collect lung tissues and bronchoalveolar lavage fluid (BALF). The concentrations of interleukin-1beta (IL-1β), tumor necrosis factor-alpha (TNF-α) and HMGB1 in BALF were determined by enzyme-linked immunosorbent assay. The pathological results were observed by hematoxylin-eosin staining, and lung injury was assessed and scored. The wet/dry (W/D) weight ratio of lung tissues was calculated. The expression of HMGB1 and HSF1 mRNA in lung tissues (by quantitative real-time polymerase chain reaction) and expression of HMGB1 and HSF1 protein in lung tissues (by Western blot) were determined. Results:Compared with group C, PaO 2 was significantly decreased at 4 h of ventilation, the concentrations of TNF-α, IL-1β and HMGB1 in BALF, W/D ratio and lung injury score were increased, and the expression of HMGB1 protein and mRNA in lung tissues was up-regulated in group VILI, group NV and group siRNA ( P<0.05 or 0.01). Compared with group VILI and group NV, PaO 2 was significantly decreased at 4 h of ventilation, the concentrations of TNF-α, IL-1β and HMGB1 in BALF, W/D ratio and lung injury score were increased, and the expression of HMGB1 protein and mRNA in lung tissues was up-regulated, and the expression of HSF1 protein and mRNA was down-regulated in group siRNA ( P<0.05 or 0.01). There was no significant difference in the parameters mentioned above between group VILI and group NV ( P>0.05). Conclusions:HSF1 is involved in the endogenous protective mechanism underlying VILI in mice, which may be related to the down-regulation of HMGB1 expression and attenuation of inflammatory responses in lung tissues.

Objective:To evaluate the effects of GSK484 on ventilator-induced lung injury (VILI) and neutrophil extracelluar traps (NETs) in mice.Methods:Forty-eight SPF healthy male C57BL/6 mice, aged 5-6 weeks, weighing 15-20 g, were divided into 4 groups ( n=12 each) by a random number table method: spontaneous breathing group (group S), spontaneous breathing+ GSK484 intervention group (group SG), VILI group (group V), and VILI + GSK484 intervention group (group VG). The animals kept spontaneous breathing for 4 h after tracheal intubation in S and SG groups. The animals were mechanically ventilated for 4 h (tidal volume 30 ml/kg, respiratory rate 75 breaths/min, inspiratory/expiratory ratio 1∶2, positive end-expiratory pressure 0 mmHg, fraction of inspired oxygen 21%) in V and VG groups. At 3 days before developing the VILI model, GSK484 4 mg/kg was intraperitoneally injected once a day in SG and VG groups, while the equal volume of normal saline was given instead in S and V groups. Blood samples were collected from the abdominal aorta for blood gas analysis at 4 h of spontaneous breathing or mechanical ventilation, and PaO 2 was recorded. The mice were then sacrificed and bronchoalveolar lavage fluid (BALF) was collected and lung tissues were obtained for microscopic examination of the pathological changes (with a light microscope after HE staining) which were scored and for determination of wet to dry weight ratio (W/D ratio), concentrations of interleukin-1beta (IL-1β), IL-6, tumor necrosis factor-alpha (TNF-α) and myeloperoxidase (MPO) in BALF (by enzyme-linked immunosorbent assay), expression of peptidylarginine deiminase 4 (PAD4), neutrophil elastase (NE), high mobility group box 1 (HMGB1) and citrullinated-histone 3 (Cit-H3) in lung tissues (by Western blot). Results:Compared with S and SG groups, the lung injury score and W/D ratio were significantly increased, PaO 2 was decreased, concentrations of IL-1β, IL-6, TNF-α and MPO in BALF were increased, and the expression of PAD4, NE, HMGB1 and Cit-H3 in lung tissues was up-regulated in V and VG groups ( P<0.05). Compared with group V, the lung injury score and W/D ratio were significantly decreased, PaO 2 was increased, the concentrations of IL-1β, IL-6, TNF-α and MPO in BALF were decreased, and the expression of PAD4, NE, HMGB1 and Cit-H3 was down-regulated in group VG ( P<0.05). Conclusions:GSK484 can alleviate VILI in mice, and the mechanism is associated with inhibition of PAD4, reduction of the production of NETs and attenuation of inflammatory responses in lung tissues.

Objective:To evaluate the effect of sitagliptin on the expression of airway mucin 5AC (MUC5AC) in mice with endotoxin-induced lung injury.Methods:Thirty-six healthy male SPF C57BL/6 mice, aged 6-8 weeks, weighing 20-25 g, were divided into 3 groups ( n=12 each) using a random number table method: control group (group C), endotoxin-induced lung injury group (group L), and endotoxin-induced lung injury+ sitagliptin group (group S). Lipopolysaccharide (LPS) 3 mg/kg was intratracheally infused to prepare endotoxin-induced lung injury model in L and S groups, while the equal volume of normal saline was given instead in group C. Sitagliptin 100 mg/kg was intraperitoneally injected at 1 h before LPS infusion in group S, and normal saline was intraperitoneally injected at 1 h before endotracheal infusion in C and L groups. The arterial blood samples from femoral artery were taken at 24 h of LPS or normal saline infusion for measurement of PaO 2 and glucose levels.The mice were then sacrificed, and broncho-alveolar lavage fluid (BALF) and lung tissues were collected for determination of the concentrations of interleukin-6 (IL-6), interleukin-1beta (IL-1β), and tumor necrosis factor-alpha (TNF-α)in serum and BALF (by enzyme-linked immunosorbent assay), wet/dry weight ratio (W/D ratio), expression of MUC5AC (by immunohistochemistry and immunohistochemical comprehensive score), and expression of MUC5AC mRNA in lung tissues (by quantitative real-time polymerase chain reaction) and for examination of the pathological changes of lung tissues (using haematoxylin and eosin staining) which were scored. Results:Compared with group C, PaO 2 was significantly decreased, the glucose levels, W/D ratio and lung injury score were increased, the concentrations of IL-6, IL-1β and TNF-α in serum and BALF were increased, and the expression of MUC5AC mRNA in lung tissues was up-regulated in L and S groups( P<0.05). Compared with group L, PaO 2 was significantly increased, the glucose levels, W/D ratio and lung injury score were decreased, the concentrations of IL-6, IL-1β and TNF-α in serum and BALF were decreased, and the expression of MUC5AC mRNA in lung tissues was down-regulated in group S( P<0.05). Conclusions:The mechanism by which sitagliptin alleviates endotoxin-induced lung injury is related to down-regulation of MUC5AC expression in mice.

Objective:To evaluate the role of inositol-requiring kinase 1α-X-box binding protein 1 (IRE1α/XBP1) signaling pathway in endoplasmic reticulumin in endotoxin-induced acute lung injury (ALI) in mice and the relationship with NOD-like receptor pyrin domain containing 3 (NLRP3) inflammasomes.Methods:Thirty-six SPF-grade healthy male C57BL/6 mice, aged 6-8 weeks, weighing 25-30 g, were divided into 3 groups ( n=12 each) according to the random number table method: control group (group C), endotoxin-induced ALI group (group ALI) and endotoxin-induced ALI+ STF-083010 group (group ST). The ALI model was established by inhaling nebulized lipopolysaccharide (LPS) 3 mg/ml for 30 min in ALI and ST groups, while the equal volume of nebulized normal saline was given in group C. IRE1α/XBP1 signaling pathway inhibitor STF-083010 50 mg/kg was intraperitoneally injected at 1 h before inhaling LPS in group ST, while the remaining two groups received the equal volume of normal saline intraperitoneally. Mice were sacrificed at 24 h after inhaling nebulized LPS or normal saline, bronchoalveolar lavage fluid (BALF) were collected and lung tissues were removed for microscopic examination of the pathological changes (by HE staining) which were scored and for determination of wet/dry lung weight ratio (W/D ratio), concentrations of interleukin-1beta (IL-lβ) and IL-18 in BALF (by enzyme-linked immunosorbent assay) and expression of phosphorylated IRE1α (p-IRE1α), XBP1s, NLRP3, ASC and caspase-1 in lung tissues (by Western blot). Results:Compared with group C, the W/D ratio, lung injury score and concentrations of IL-1β and IL-18 in BALF were significantly increased, and the expression of p-IRE1α, XBP1s, NLRP3, ASC and caspase-1 in lung tissues was up-regulated in group ALI and group ST ( P<0.001). Compared with group ALI, the W/D ratio, lung injury score and concentrations of IL-1β and IL-18 in BALF were significantly decreased, and the expression of p-IRE1α, XBP1s, NLRP3, ASC and caspase-1 protein in lung tissues was down-regulated in group ST ( P<0.001). Conclusions:IRE1α/XBP1 signaling pathway is involved in LPS-induced ALI in mice, and the mechanism is related to activation of NLRP3 inflammasomes.

Objective:To evaluate the effect of irisin on the alveolar macrophage polarization in a rat model of ventilator-induced lung injury (VILI).Methods:Thirty SPF healthy adult male Sprague-Dawley rats, aged 6-8 weeks, weighing 200-250 g, were divided into 3 groups ( n=10 each) using a random number table method: control group (group C), VILI group (group V) and irisin group (group I). The rats were mechanically ventilation (tidal volume 20 ml/kg, respiratory rate 80 times/min, inhaled oxygen concentration 21%, inspiratory/expiratory ratio 1∶2, positive end-expiratory pressure 0) for 4 h to develop VILI model.Group C kept spontaneous breathing for 4 h. Irisin 1 μg/kg was injected via the tail vein at 30 min before tracheal intubation in group I, while the equal volume of normal saline was given instead in the other groups.The rats were sacrificed at 4 h of mechanical ventilation, the lung tissues were removed for examination of pathological changes which were scored and for determination of wet to dry weight ratio (W/D ratio), and bronchoalveolar lavage fluid (BALF) was collected for determination of concentrations of interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-α) and IL-10 (by enzyme-linked immunosorbent assay), expression of inducible nitric oxide synthase (iNOS), argininase 1 (Arg-1), and phosphorylated nuclear factor kappa B (p-NF-κB) p65 and p-NF-κB p50 in alveolar macrophages (by Western blot), and percentage of M1 and M2 alveolar macrophages and M1/M2 ratio (by flow cytometry). Results:Compared with group C, the W/D ratio, lung injury score, and concentrations of IL-6, TNF-α and IL-10 in BALF were significantly increased, the expression of iNOS, Arg-1, p-NF-κB p65 and p-NF-κB p50 was up-regulated, and the percentage of M1 and M2 alveolar macrophages and M1/M2 ratio were increased in group V and group I ( P<0.05). Compared with group V, the W/D ratio, lung injury score, and concentrations of IL-6 and TNF-α in BALF were significantly decreased, the expression of iNOS and p-NF-κB p65 was down-regulated, the percentage of M1 alveolar macrophages and M1/M2 ratio were decreased ( P<0.05), and no significant change was found in levels of IL-10 and Arg-1 in BALF, percentage of M2 alveolar macrophages and expression of p-NF-κB p50 in group I ( P>0.05). Conclusions:The mechanism by which irisin reduces VILI may be related to inhibition of NF-κB signaling pathway activation and reduction of alveolar macrophage polarization to M1 phenotype in rats.

Objective:To evaluate the role of cathepsin B (CTSB) in mechanical ventilator-induced lung injury (VILI) in rats and the relationship with NOD-like receptor pyrin domain containing 3 (NLRP3) inflammasome.Methods:Thirty-six SPF-grade healthy male Sprague-Dawley rats, aged 6-8 weeks, weighing 220-300 g, were divided into 3 groups ( n=12 each) by the random number table method: control group (group C), VILI group (group V) and VILI + CA074-me group (group Me). CA074-me 5 mg/kg was intraperitoneally injected in group Me, while the equal volume of normal saline was given instead in group C and group V. Group C kept spontaneous breathing for 4 h, and the animals were mechanically ventilated (tidal volume 20 ml/kg, respiratory rate 80 breaths/min, fraction of inspired oxygen 21%, PEEP 0 cmH 2O). Blood samples from femoral artery were collected for arterial blood gas analysis before tracheal intubation and after spontaneous breathing or ventilation, and PaO 2 was recorded.Rats were sacrificed, and bronchoalveolar lavage fluid (BALF) was collected and lung tissues were collected for determination of the wet/dry lung weight ratio (W/D ratio), serum interleukin-1beta (IL-1β) and IL-18 concentrations in BALF (by enzyme-linked immunosorbent assay), expression of CTSB, NLRP3, apoptosis-associated speck-like protein containing a caspase-1 recruitment domain (ASC) and caspase-1 mRNA in lung tissues (quantitative real-time polymerase chain reaction), and expression of CTSB, NLRP3, ASC and caspase-1 in lung tissues (by Western blot) and for microscopic examination of the pathological changes (using HE staining). Lung injury was assessed and scored. Results:Compared with group C, PaO 2 was significantly decreased after the end of ventilation, the lung injury score, W/D ratio and concentrations of IL-1β and IL-18 in serum and BALF were increased, and the expression of CTSB, NLRP3, ASC and caspase-1 protein and mRNA in lung tissues was up-regulated in group V and group Me ( P<0.01). Compared with group V, PaO 2 was significantly increased after the end of ventilation, the lung injury score, W/D ratio and concentrations of IL-1β and IL-18 in serum and BALF were decreased, and the expression of CTSB, NLRP3, ASC and caspase-1 protein and mRNA in lung tissues was down-regulated in group Me ( P<0.01). Conclusions:CTSB is involved in VILI in the rats, and the mechanism may be related to activation of NLRP3 inflammasomes.