We found no differentially methylated CpG sites associated with COPD diagnosis in airway fibroblasts; however, one CpG site (cg18773129; COMT) in parenchymal fibroblasts showed increased DNA methylation in COPD patients compared to healthy controls (FDR < 0.2, Δβ > 0.05) (Fig. 5). This evidence concerns the gene COMT and chronic obstructive pulmonary disease.