To our knowledge, this is the first report of TGF-β3 protein expression and localization in the lower airways of patients with stable COPD and is in keeping with the results of decreased TGF-β3 mRNA expression in the peripheral lung of patients with more severe COPD31, 35 and of increased TGF-β3 mRNA expression in the peripheral lung of smokers compared with nonsmokers.31 This evidence concerns the gene TGFB3 and chronic obstructive pulmonary disease.