| Background and purpose:Lung injury due to HC smoke inhalation in closed environment is very common in military personnel and leads to a high incidence of pulmonary complications and mortality.It has been considered that the mechanism of inhalation lung injury has been non-specific,and the treatment has been limited to symptomatic treatment.To clarify the mechanism of toxic gas inhalation injury and to find new treatment methods have been the focus of recent research.The aim of this study was to uncover the underlying mechanisms of lung injury due to HC smoke inhalation by using a rat model.Methods:This study establishes a rat model of smoke pot(HC smoke)inhalation injury,independently develops a static smoke box which can determine smoke composition and concentration,makes simulated smoke pot,and determines the concentration of zinc ion in HC smoke.Histopathology analysis of rat lungs after zinc chloride smoke inhalation was performed by using haematoxylin and eosin(H&E)and Mallory staining,and biochemical detection of rat serum was performed.First,isobaric tags for relative and absolute quantization(iTRAQ)and weighted gene co-expression network analysis(WGCNA)were used to identify important differentially expressed proteins.Gene Ontology(GO)and Kyoto Encyclopedia of Genes and Genomes(KEGG)pathway analyses were used to study the biological functions of differentially expressed proteins.Then,analysis of lung injury repairrelated differentially expressed proteins in the early(day 1 and day 2)and middle-late stages(day 7 and day 14)of lung injury after smoke inhalation was performed,followed by the protein-protein interaction(PPI)analysis of these differentially expressed proteins.Finally,the injury repair-related proteins PARK7,FABP5 and Galectin-7 were validated by immunohistochemistry and western blot analysis.PARK7 BALF and serum ELISA were detected in rats and patients.Results:Rat mortality was significantly correlated with zinc ion concentration of smoke.Pathological study of rat lung showed that congestion,edema and destruction of alveolar structure appeared in the early stage of exposure,emphysema and pulmonary fibrosis appeared in the middle and late stage of exposure,and biochemical indexes increased significantly in the early stage of exposure.A total of 27 common differentially expressed proteins were obtained on days 1,2,7 and 14 after smoke inhalation.WGCNA showed that the turquoise module(which involved 909 proteins)was most associated with smoke inhalation time.Myl3,Ckm,Adrml and Igfbp7 were identified in the early stages of lung injury repair.Gapdh,Acly,Tnni2,Actal,Actn3,Pygm,Eno3 and Tpil(hub proteins in the PPI network)were identified in the middle-late stages of lung injury repair.Eno3 and Tpil were both involved in the glycolysis/gluconeogenesis signalling pathway.According to the current research hotspots,it was found that the downregulated zinc channel TRPM7 and the solute carrier Slc25a51 which may be involved in zinc transport,play an important role in lung injury of HC smoke.Three proteins,Galectin-7,PARK7 and FABP5,were screened from 55 hub proteins for validation.Immunohistochemistry and WB re-validation were performed on rat lung tissues.WB of Galectin-7 was negative.WB of FABP5 was consistent with proteomic analysis,and immunohistochemical results of FABP5 were negative.The immunohistochemistry and WB expression of PARK7 was consistent with the proteomics analysis.ELISA showed that the PARK7 level of BALF increased significantly on the 1st and 2nd day after inhalation injury of HC smoke in rats and humans,and gradually decreased to normal in the later period.The PARK7 level in serum of rats and moderate or severe patients decreased in acute phase within 7 days after inhalation injury.In the mild injury group,the serum level of PARK7 increased in the acute stage.It is suggested that PARK7 is not only involved in injury repair,but also can be used as a biomarker to reflect the severity of inhalation injury. |
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