The negative correlation between TGF-β and lung function (FEV1 and FEV1/FVC) in our study echoes the findings of Kraik et al., who reported that TGF-β signaling was upregulated in airway smooth muscle cells in COPD patients, contributing to collagen deposition and airway narrowing [32]. Here, TGFB1 is linked to chronic obstructive pulmonary disease.