Using Proteome Profiler Human Angiogenesis Array Kit, as shown in Figure 1A, with a total of 55 angiogenesis-associated proteins, the following 42 proteins expressions were detected in the plasma of COPD and COPD-PH patients: ANG, Ang-1, Ang-2, Angiostatin, AR, Artemin, TF, CXCL16, DPPIV, EGF, PK1, CD105, Endostati, Endothelin-1, FGF acidic, GDNF, HB-EGF, HGF, IGFBP-1, IGFBP-2, IGFBP-3, IL-1β, Leptin, MCP-1, MMP-8, MMP-9, TSG-14, PD-ECGF, PDGF-AA, PDGF-AB, CXCL4, PlGF, Prolactin, PAI-1, TIMP-1, TIMP-4, TSP-1, TSP-2, uPA, Vasohibin, VEGF, and VEGF-C. Here, GDNF is linked to chronic obstructive pulmonary disease.