Although some COPD biomarker investigations have focused on single candidate mRNA or miRNA (e.g., IRF-3, miR-199a-5p) (Ishii et al., 2017; Takei et al., 2019), there is no single mRNA, miRNA, or other molecule that can fully explain the development of COPD. Here, IRF3 is linked to chronic obstructive pulmonary disease.