Matrix metalloproteinases in cystic fibrosis: pathophysiologic and therapeutic perspectives

Abstract:

Cystic fibrosis (CF) is the most common inherited disease in the Caucasian population. CF is caused by loss-of-function mutations in the CFTR gene leading to an altered electrolyte and water movement into the airway surface liquid, dehydration of the mucus layer, defective mucociliary clearance, and increased susceptibility to airway bacterial infections. CF is characterized by airway neutrophilic inflammation and activation of airway epithelial cells leading to increased airway levels of various matrix metalloproteinases (MMPs). Herein, we review MMP structure, regulation, and activity, along with the literature on MMPs expression in CF and the contributions of MMPs to CF pathogenesis. Numerous studies report elevated levels of MMPs (especially MMP-8, MMP-7, and MMP-9) in blood and/or lung samples from CF patients and have correlated MMP levels with measures of lung inflammation and injury and/or clinical parameters. No study has yet investigated the contributions of MMPs to the pathogenesis of CF using MMP gene-targeted murine of CF. Based upon the known activities of MMPs in animal models of other lung diseases, we hypothesize that some MMPs (such as MMP-8 and MMP-9) may amplify airway inflammation, and promote airway injury and airway-remodeling processes, or inhibit chloride epithelial transport by inhibiting activation of the CFTR (MMP-2). Other MMPs (such as MMP-7 and MMP-12) may limit the severity of CF by activating host defense proteins to enhance pathogen clearance from the airways, directly killing pathogens that colonize the airways of CF patients and/or promoting epithelial repair. We discuss potential approaches to selectively target MMPs to develop novel therapies that limit the high morbidity and mortality associated with CF.

Keywords::

• tissue inhibitor of metalloproteinases
• airway inflammation
• airway injury
• airway infection
• airway repair
• proteolysis

Acknowledgments

This work was supported by the Public Health Service, the National Heart, Lung, and Blood Institute Grants HL111835, PO1 HL105339, P01 HL114501, and AI111475-01, the Flight Attendants Medical Research Institute grant CIA123046, and the Brigham and Women’s Hospital–Lovelace Respiratory Research Institute Consortium.

Disclosure

The authors report no conflicts of interest in this work.