In this regard, evidence for a reduction in mature elastin content has been unexpectedly obtained in fibrotic diseases such as usual interstitial pneumonia (UIP) and cryptogenic organizing pneumonia (COP) using modern non-invasive microscopy technology [23], whereas elastin-degradation products have been documented in animal models of acute lung injury ending in fibrosis [19, 20] and in human diseases as diverse as chronic obstructive pulmonary disease (COPD) [24], acute respiratory distress syndrome (ARDS) [25] and, idiopathic pulmonary fibrosis (IPF) [26]. This evidence concerns the gene ELN and chronic obstructive pulmonary disease.