The role of proteinases from Pseudomonas aeruginosa and polymorphonuclear leukocytes in cystic fibrosis

In cystic fibrosis (CF) a defective chloride channel leads to viscous secretions and impaired mycociliary clearance which in turn leads to chronic endobronchial bacterial infection mostly caused by Pseudomonas aeruginosa. In the early infectious process, three P. aeruginosa proteinases, alkaline proteinase, elastase and LasA, are thought to contribute to the pathogenicity of CF lung disease by facilitating tissue colonization, causing tissue damage, cleaving immunoglobulins and other soluble proteins as well as cell surface proteins. During the chronic course of the infection, the P. aeruginosa proteinases are neutralized by specific host antibodies, and proteinases released from activated neutrophils represent the dominating proteolytic activity in CF airways. Since neutrophil proteinases reveal similar enzymatic activities as P. aeruginosa proteinases, they may provide favorable growth conditions for the opportunistic bacteria.