title: Selective induction of tissue inhibitor of metalloproteinase-1 in bleomycin-induced pulmonary fibrosis.
abstract: Tissue inhibitors of metalloproteinases (TIMPs) are multifunctional proteins that have the capacity to modify cellular activities and to modulate matrix turnover. We demonstrate that TIMP-1 messenger RNA (mRNA) and protein expression are selectively and markedly increased in a murine model of bleomycin-induced pulmonary fibrosis. Northern analysis showed that lung steady-state TIMP-1 mRNA levels increased 14-fold after bleomycin administration compared with control mice. Expression of the genes for TIMP-2, TIMP-3, and interstitial collagenase (matrix metalloproteinase-13) was unaltered in the injured lung. In situ hybridization demonstrated that TIMP-1 gene induction was spatially restricted to areas of lung injury. Metalloproteinase inhibitory activity of relative molecular mass of ~ 21 to 28 kD, corresponding to the molecular weights for TIMP-1 and TIMP-2, was identified in lung extracts of bleomycin-injured mice by reverse zymography. Western analysis demonstrated that TIMP-1 protein levels in bronchoalveolar lavage fluid (BALF) of bleomycin-treated mice increased 220- and 151-fold at Days 4 and 28, respectively, compared with control mice. TIMP-2 immunoreactive protein in the BALF increased 20- and 103-fold relative to controls at Days 4 and 28, respectively. These results demonstrate that TIMP-1 gene expression is selectively increased, and that the expression of TIMP-1 and TIMP-2 is differentially regulated in bleomycin-induced pulmonary fibrosis. The profound and durable increase in TIMP-1 and TIMP-2 proteins suggests an important regulatory role for these antiproteases in the inflammatory and fibrotic responses to bleomycin-induced lung injury.
authors.affiliation: Section of Pulmonary and Critical Care Medicine, Fred Hutchinson Cancer Research Center, Department of Medicine, University of Washington School of Medicine, Seattle, Washington 98109-1024, USA. dmadtes@fhcrc.org
authors.forename: D K
authors.initials: DK
authors.lastname: Madtes
authors.forename: A L
authors.initials: AL
authors.lastname: Elston
authors.forename: L A
authors.initials: LA
authors.lastname: Kaback
authors.forename: J G
authors.initials: JG
authors.lastname: Clark
mesh_terms: D000818:Animals; D001761:Bleomycin; D001992:Bronchoalveolar Lavage Fluid / Q000737:chemistry; D017364:Collagenases / Q000235:genetics / Q000378:metabolism; D004195:Disease Models, Animal; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D008168:Lung / Q000378:metabolism / Q000473:pathology; D008297:Male; D053509:Matrix Metalloproteinase 13; D051379:Mice; D011347:Procollagen / Q000235:genetics / Q000378:metabolism; D011658:Pulmonary Fibrosis / Q000139:chemically induced / Q000378:metabolism* / Q000473:pathology; D012333:RNA, Messenger / Q000096:biosynthesis*; D019715:Tissue Inhibitor of Metalloproteinase-1 / Q000032:analysis / Q000096:biosynthesis* / Q000235:genetics; D019716:Tissue Inhibitor of Metalloproteinase-2 / Q000032:analysis / Q000096:biosynthesis / Q000235:genetics; D019717:Tissue Inhibitor of Metalloproteinase-3 / Q000096:biosynthesis / Q000235:genetics
chemical_list: D011347:Procollagen; D012333:RNA, Messenger; D019715:Tissue Inhibitor of Metalloproteinase-1; D019717:Tissue Inhibitor of Metalloproteinase-3; D001761:Bleomycin; D019716:Tissue Inhibitor of Metalloproteinase-2; D017364:Collagenases; D053509:Matrix Metalloproteinase 13; C507081:Mmp13 protein, mouse