PIR and chronic obstructive pulmonary disease: We further studied whether severity of COPD was correlated with genetic expression of PIR, FGB, and IL-6. Notably, relative to COPD, PIR was found to be the most activated gene to have a significant correlation with early COPD (Figure 5C-5D, P < 0.0001), followed by FGB (Figure 5D, P = 0.0006), while IL-6 had no significant association (Figure 5D, P = 0.3742) (GSE5060, n = 38).