ELANE and infection: We, therefore, hypothesized that ecotin in the biofilm matrix may protect P. aeruginosa biofilms against proteases such as neutrophil elastase, an enzyme the bacteria commonly come into contact with during chronic biofilm-based infections (10) via the following two mechanisms: (i) ecotin may protect proteins in the matrix from proteolytic degradation by neutrophil elastase, and (ii) ecotin may protect biofilm cells from neutrophil elastase-mediated death.