Comparing E-COPD to NE-COPD, we found that activities of MIF-CXCR4, MIF-CD74, MIF-CD44, and CXCL11-CCR5 ligand-receptor pairs were upregulated in E-COPD, whereas IL7-IL2RG, IL1β-IL12RB2, IL18-IL18RAP and ICAM1-IL2RG ligand-receptor pairs were upregulated in NE-COPD (Fig. 8e). Here, CXCR4 is linked to chronic obstructive pulmonary disease.