ELN and chronic obstructive pulmonary disease: As shown in the scheme of Figure 2, this imbalance between protease(s) degrading the parenchymal extracellular matrix and their inhibitors is responsible for the destruction of lung elastin and, if it is persistent or recurrent over years, it results in respiratory complications, such as chronic obstructive pulmonary disease (COPD) [2,3,4,5].