FN1 and acute respiratory distress syndrome: However, serprocidins display proteolytic activity against a variety of extracellular matrix components, such as elastin, fibronectin, laminin, type IV collagen, and vitronectin1 and excessive release from neutrophils has been implicated in pathophysiological conditions such as acute respiratory distress syndrome (ARDS), bronchiectasis, emphysema, and sepsis4–8.