Screening and validation of pyroptosis-related genes in COPD based on bioinformatics methods

Objective: To screen and analyze the key genes related to pyroptosis in chronic obstructive pulmonary disease(COPD)by bioinformatics.Methods: Firstly, differential analysis was performed on chronic obstructive pulmonary disease data set GSE38974, and intersection of the obtained differential genes and pyroptosis related genes was used to obtain the differentially expressed pyroptosis-related genes (DEprGs).GO and KEGG functional enrichment analysis and PPIanalysis were performed for DEprGs.Four algorithms of Cytoscape software and cytohubba were applied to analyze PPIresults and intersection of key genes were obtained.GSE38974 and GSE47460 data sets were used to verify key genes again and select the most significant core genes.Twelve C57BL/6 mice were exposed respectively to air and tobacco smoke for 24 weeks, and the pathological changes of mouse lung tissues were observed by HE staining.Real-time fluorescence quantitative polymerase chain reaction(RT-qPCR)was used to verify the differential expressions of the most critical genes in the animal model.Results: A total of 32 DEprGs were obtained by the intersection of GSE38974 and pyroptosis genes, and 7 key genes were obtained by further analysis of PPI.Seven key genes were verified again with GSE38974 and GSE47460 data sets.Only two core genes, NAIP and HDAC6, were expressed with significant differences (P＜0.01) in the two data sets. NAIP was up-regulated, HDAC6 was downregulated.HE staining showed that compared with the air exposure group, the alveolar wall in the tobacco smoke exposure group was thinner, fractured and fused; the alveolar cavity was significantly enlarged and the inflammatory cell infiltration was obvious.The mean linear intercept in the smoking group was significantly higher than that in the air group (P＜0.05).The results of bioinformatics analysis were consistent with the results of core gene test,and correlation analysis showed that NAIP and HDAC6 were correlated with the mean alveolar spacing of mice (P＜0.05).Conclusion: In COPD, NAIP is highly expressed in COPD,which may be involved in the occurrence and development of COPD.The low expression of HDAC6 may be a potential protective factor.