Network representing the correlation between serum cytokine levels and skeletal muscles gene expression in the human COPD study. (A) The force-directed network representation linking the serum level of selected chemokines/cytokines (round nodes) with enriched KEGG pathways (yellow hexagons). Each circular node has been divided into two sectors, representing COPD patients with (1) a normal FFMI and (2) a low FFMI. A red sector indicates that the cytokine level is significantly higher compared to matched controls, and a grey-coloured sector indicates that the serum protein level is stable between groups. Blue edges mean negative correlation, whereas red edges mean positive correlation. (B, C) Scatterplots representing the association between serum levels of CXCL9 (x-axis) and muscle mRNA expression (y-axis) of examples of genes involved in oxidative phosphorylation (B) and ribosomal biogenesis (C).