1Dept of Medicine, Division of Pulmonary, Allergy and Critical Care Medicine, University of Alabama at Birmingham, Birmingham, AL, USA
2Program in Protease and Matrix Biology, University of Alabama at Birmingham, Birmingham, AL, USA
3Gregory Fleming James Cystic Fibrosis Research Center, University of Alabama at Birmingham, Birmingham, AL, USA
4Lung Health Center, University of Alabama at Birmingham, Birmingham, AL, USA
8Medicine Service, United States Department of Veterans Affairs Medical Center, University of Alabama at Birmingham, Birmingham, AL, USA