Albeit we cannot fully exclude that other MMPs e.g., MMP-8, or additional factors may also play a role, MMP-12 is mainly produced by AMΦ and has been convincingly demonstrated before to be involved in acute and chronic pulmonary inflammatory diseases associated with an intense airway remodeling, such as emphysema formation and COPD. This evidence concerns the gene MMP8 and chronic obstructive pulmonary disease.