Effect of smoking on expression and localization of aquaporin1(AQP1)in lung tissue
Objective To investigate the expression changes of aquaporin 1(AQP1)in chronic obstructive pulmonary disease(COPD)and smoking—induced mouse models.Methods 30 SPF grade Kunming mice,4 weeks of age,were selected and divided into control group,3-month smoking group and 6-month smoking group with 10 mice each.COPD mice model was induced by smoking,and control mice did not undergo any treatment.AQP1 protein expression was measured in lung tissues of each group by immuno-histochemistry and Western blot.In vivo use of nicotine to stimulate the human non-small cell lung cancer cell line A549,which were divided into control(PBS),3 μmol/L nicotine(3 μmol/L)and 5 μmol/L nico-tine(5 μmol/L),for AQP1 protein expression in A549 cells in each group.Differential expressed gene analysis of COPD transcriptome data with"limma"function;Pearson correlation analysis between AQP1 expression and differentially expressed genes;and enrichment analysis of highly correlated genes using the GeneMANIA platform.Results Immunohistochemical results showed that AQP1 in the lung tissue of the control mice was mainly distributed in the capillary endothelial cells and red blood cells of the lung tissue,and it also slightly distributed in the apical membrane of the type Ⅱ alveolar epithelial cells.HE staining results showed that the control mice had no inflammatory cells in alveoli and interstitium and smooth re-spiratory tract.The lung tissue of mice in the 3-month smoking group showed the formation of pulmonary alveoli,inflammatory cell infiltration around small airways and blood vessels,and accumulation of viscous secretions;A large number of pulmonary alveoli were observed in the lung tissue of mice in the 6-month smoking group,and there were numerous inflammatory cell clusters around the blood vessels.The west-ern blot showed that AQP1 protein expression was reduced by 40%and 60%compared with the control group(P<0.01).In vitro nicotine stimulation showed that AQP1 protein expression was increased in 3 μmol/L nicotine(P<0.05);AQP1 protein expression was more increased in 5 μmol/L nicotine(P<0.01).Bioinformatics analysis showed that in dataset GSE103174,AQP1 was significantly decreased in COPD lung tissue compared with normal lung tissue(P=0.000 13).Analysis of the differentially ex-pressed genes found that,compared with the normal group,COPD patients had 62 genes up-regulated and 56 genes down-regulated;Pearson correlation analysis found that,the correlation coefficient between Epi-regulin(EREG),prostaglandin G/H synthase 2(PTGS 2),amphiregulin(AREG)and AQP1(R2)was>0.5;The results of the enrichment analysis showed that,EREG,interleukin-6(IL-6),and AREG were involved in the process of epithelial cell proliferation,Cytochrome P450 family 1 subfamily B member 1(CYP1B1),interleukin-1β(IL-1β),IL-6 and PTGS 2 were involved in the production of vascular endotheli-al growth factor.Conclusion The expression of AQP1 protein in lung tissue of COPD patients and smok-ing induced COPD mice model were decreased,which may not be related to the increase of AQP1 caused by nicotine stimulation of alveolar epithelial cells.