For surfactant protein B (SFTPB, downregulated in AE of COPD patients), a role in COPD pathogenesis was previously established based on genetic polymorphisms 50–52, decreased protein concentrations in bronchoalveolar lavage fluid (BALF)53 of COPD patients and in vitro experiments41. This evidence concerns the gene SFTPB and chronic obstructive pulmonary disease.