TGFB3 and chronic obstructive pulmonary disease: TGF-β3 protein release from bronchial epithelium in vitro and BAL TGF-β3 levels were similar between patients with COPD and control subjects.27, 28 We were unable to find any significant differences between patients with stable COPD and control subjects in TGF-β2 and TGF-βR expression and localization in the lower airways.