Fig. 3

Remodeling of the lung extracellular matrix. During progression of COPD, the basement membrane (BM) and the interstitial matrix (IM) is remodeled, resulting in a disruption of the interface between these two extracellular matrix (ECM) compartments. Type VI collagen is situated in this interface, and consequently fragments of type VI collagen, may be particularly related to disease progression and lung tissue remodeling. In addition, the chronic inflammatory response may in part be accompanied by persistent neutrophil presence in affected tissues, which normally would be resolved in the later stages of inflammation resolution. These inflammatory cells produce high amounts of neutrophil elastase capable of degrading the elastin of the lungs found in the interstitial matrix, which is essential for lung tissue elasticity. Both the type VI collagen and elastin remodeling, in addition to the remodeling of other ECM components, results in the release of small protein fragments (neo-epitopes) to the bloodstream. Modified with permission from [65]