MMP12 and chronic obstructive pulmonary disease: There is synergy between NE and MMP-12 (macrophage elastase) to promote tobacco smoke-induced COPD lung pathology, as MMP-12 degrades the NE inhibitor, α-1 antitrypsin [108] and NE degrades the MMP-12 inhibitor, TIMP1 [40], resulting in unrestrained protease activities.