title: Role of proteolysis and apoptosis in regression of pulmonary vascular remodeling.
abstract: Remodeled pulmonary arteries return to normal structural conditions after the increase in pulmonary artery flow resistance is reversed. We studied whether proteolysis of extracellular matrix proteins and apoptosis occur during reversal of remodeling produced by chronic hypoxia in the rat. Main pulmonary arteries were removed at different times during a 10-day period of exposure to 10% O2 and 14 days after return to air. Content and rates of degradation of collagen and elastin as well as immunoreactive collagenase in tissue and isolated mast cells were measured. Immunoblots for collagenase and tissue inhibitor of metalloproteinases (TIMP) were performed. Apoptosis was assessed by cleavage of DNA and TUNEL assay. Excess collagen and elastin present at 10 days of hypoxia decreased to near normal levels after 3-5 days of air. Transient increases in collagenolytic and elastolytic enzyme activities accompanied the rapid decrease in matrix proteins. Mast cells containing collagenase accumulated in remodeled pulmonary arteries, and the active form of collagenase appeared at the time of peak proteolytic activity. TIMP increased during remodeling. Apoptosis was maximal 3 days after return to air. Our results suggest that activation of enzymes, which degrade matrix proteins, and apoptosis play a role in resolution of vascular remodeling.
authors.affiliation: Department of Medicine, University of Medicine and Dentistry of New Jersey - Robert Wood Johnson Medical School, Piscataway 08854-5635, USA. riley@umdnj.edu
authors.forename: D J
authors.initials: DJ
authors.lastname: Riley
authors.forename: S
authors.initials: S
authors.lastname: Thakker-Varia
authors.forename: F J
authors.initials: FJ
authors.lastname: Wilson
authors.forename: G J
authors.initials: GJ
authors.lastname: Poiani
authors.forename: C A
authors.initials: CA
authors.lastname: Tozzi
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000502:physiology*; D001808:Blood Vessels / Q000502:physiology; D053818:Chymases; D017364:Collagenases / Q000235:genetics / Q000378:metabolism; D016326:Extracellular Matrix Proteins / Q000378:metabolism; D006976:Hypertension, Pulmonary / Q000503:physiopathology*; D015151:Immunoblotting; D007150:Immunohistochemistry; D008168:Lung / Q000378:metabolism; D008407:Mast Cells / Q000378:metabolism; D010447:Peptide Hydrolases / Q000378:metabolism*; D011651:Pulmonary Artery / Q000378:metabolism / Q000473:pathology; D011652:Pulmonary Circulation / Q000502:physiology*; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D012697:Serine Endopeptidases / Q000378:metabolism; D019715:Tissue Inhibitor of Metalloproteinase-1 / Q000235:genetics / Q000378:metabolism
chemical_list: D016326:Extracellular Matrix Proteins; D012333:RNA, Messenger; D019715:Tissue Inhibitor of Metalloproteinase-1; D010447:Peptide Hydrolases; D012697:Serine Endopeptidases; D053818:Chymases; D017364:Collagenases