Figure 5. The association analysis between the critical aging-related DEGs and lung function in COPD patients. The lung function was negatively associated with (A) NKG7 expression and (B) CKLF expression, whereas no significant associations with the expressions of (C) LRP4, (D) GOPD3 and (E) CXCL9. DEGs, differently expressed genes; COPD, chronic obstructive pulmonary disease; FEV1 (% predicted), forced expiratory volume in 1 s (FEV1) % predicted; NKG7, natural killer cell granule protein 7; CKLF, chemokine like factor; LRP4, LDL receptor related protein 4; GDPD3, glycerophosphodiester phosphodiesterase domain containing 3; CXCL9, C-X-C motif chemokine ligand 9.