Therefore, our in vitro and in vivo assays allowed us to confirm the following three observations: (1) the effect of deflamin obtained at the in vitro level agrees with the inhibition of gelatinase B activity in the COPD animal model; (2) this effect was translated into a biological benefit (attenuation of pulmonary emphysema and peribronchial fibrosis); and (3) deflamin is capable of interacting with and inhibiting both human and mouse MMP-9. This evidence concerns the gene MMP9 and pulmonary emphysema.