Matrilysin in epithelial repair and defense

Repair involves an orderly progression of events to reestablish the integri ty of the injured tissue. During each stage in this process, secreted prote inases are needed to remodel extracellular matrix, facilitate cell migratio n, and process latent proteins, among other functions. In lung epithelium, several of these processes are mediated by matrilysin, a matrix metalloprot einase (MMP); Unlike most MMPs, matrilysin is produced by intact, noninjure d airway and peribronchial epithelial cells. In other intact epithelial tis sues, namely the small intestine, matrilysin functions in host. defense by activating the latent form of defensins, a family of antimicrobial peptides . This metalloproteinase may serve a similar function in the lung. Furtherm ore, in models of airway injury, matrilysin expression is upregulated in mi grating epithelial cells, and the activity of this proteinase is required f or repair of airway wounds. These observations indicate that matrilysin ser ves key functions in both epithelial defense and repair.