Fig. 3

Hierarchical clustering and principal component analysis of the DEPs in stable and exacerbated COPD with respect to healthy controls: (a) Heatmap representing the significant DEPs in stable and exacerbated COPD with respect to healthy controls. Clustering shows the co-expression clusters among the differentially expressed proteins. Protein expression levels above the mean levels are in red, protein expression levels below the mean levels are in green. (b) Heatmap representing group averages of stable and exacerbated COPD with respect to healthy controls. (c) partial least square discriminant analysis (PLS-DA) shows the intra-group homogeneity and the inter-group variability in the three groups. There is clear separation between the exacerbated COPD with the healthy controls