Fig. 5

PPI analysis and gene correlation analysis. AThe protein–protein interactions among 9 COPD-associated pyroptosis-related genes and 26 COPD key genes. B The rank of connection degree (number) for each gene. C Correlation among the expression of 9 COPD-associated pyroptosis-related genes and 26 COPD key genes in the train set. P values are shown as: *p < 0.05. (D) Correlation among the expression of 9 COPD-associated pyroptosis-related genes and 26 COPD key genes in the test set. P values are shown as: *p < 0.05