TGFB1 and chronic obstructive pulmonary disease: At variance with the bronchial epithelium, the percentage of TGF-β1+ (Fig 2A, e-Fig 1), TGF-β3+ (Fig 2E, e-Fig 2), and CCN2+ (Fig 2G, e-Fig 3) bronchiolar epithelial cells in the peripheral airways was significantly decreased in patients with COPD compared with control smokers with normal lung function (Table 4).