Proteomics-based analysis of lung injury–induced proteins in a mouse model of common bile duct ligation

Background Lung injury is a life-threatening complication in patients with liver dysfunction. We recently provided an experimental lung injury model in mouse with common bile duct ligation. In this study, we aimed to characterize the pathologic and biochemical features of lung tissues in common bile duct ligation mice using a proteomic approach. Methods Common bile ducts of BALB/c mice, 8 weeks of age, were ligated operatively. CD31-expressing pulmonary cells were sorted with immunomagnetic microbeads, and protein profiles were examined by 2-dimensional gel electrophoresis. Based on the results of protein identification, immunohistochemistry and quantitative reverse transcription polymerase chain reaction were carried out in pulmonary and hepatic tissues. Results Two-dimensional gel electrophoresis revealed 3 major inflammation-associated proteins exhibiting considerable increases in the number of CD31-positive pulmonary cells after common bile duct ligation. Mass spectrometry analysis identified these proteins as SerpinB1a (48 kDa), ANXA1 (46 kDa), and S100A9 (16 kDa). Furthermore, the 3 proteins were more highly expressed in dilated pulmonary blood vessels of common bile duct ligation mice, in which neutrophils and monocytes were prominent, as shown by immunohistochemistry. More importantly, SerpinB1a mRNA and protein were significantly upregulated in the liver, whereas S100A9 and ANXA1 mRNA and protein were upregulated in the lungs, as shown by quantitative reverse transcription polymerase chain reaction and Western blotting. Conclusion We identified 3 proteins that were highly expressed in the lung after common bile duct ligation using a proteomics-based approach.