Secreted by neutrophils and macrophages during inflammation, elastase is a serine proteinase in the same family as chymotrypsin and has broad substrate specificity, destroys bacteria and host tissue. This protein degrades the outer membrane protein A (OmpA) of E. coli as well as the virulence factors of such bacteria as Shigella, Salmonella and Yersinia. The enzyme may play a role in degenerative and inflammatory diseases by its proteolysis of collagen-IV and elastin of the extracellular matrix. It is also an important protease enzyme that when expressed aberrantly can cause emphysema or emphysematous changes. This involves breakdown of the lung structure and increased airspaces.