Fig. 2

Schematic drawing of the basement membrane (in green) underlying the lung epithelium and the interstitial matrix (in red), supporting the tissue. After cellular damage the epithelium is compromised, clotting occurs which results in remodelling of the tissue. When overactivated, fibroblasts (blue) produce fibrillar collagen limiting oxygen diffusion. During these processes, small fragments of proteins related to these molecular events are released into the circulation, where they may be used as biomarkers