ELN and chronic obstructive pulmonary disease: In this context, different studies carried out in animal and human models have shown a protective effect of aerosolised HA and its degradation products in the airways remodelling of COPD patients, probably by adherence to the elastic fibres and protecting them against chemical hydrolysis of elastin by the pancreatic and neutrophilic elastases [35,36,37,38,39,40], not chemically inhibiting them [41].