title: Vitronectin-binding PAI-1 protects against the development of cardiac fibrosis through interaction with fibroblasts.
abstract: Plasminogen activator inhibitor-1 (PAI-1) promotes or abates fibrotic processes occurring in different organs. Binding of PAI-1 to vitronectin, an extracellular matrix component, may inhibit vitronectin-integrin complex-mediated cellular responses in pathophysiological conditions. To investigate the importance of plasmin suppression vs vitronectin-binding pathways of PAI-1 in cardiac fibrosis, we studied uninephrectomized mice fed a high salt diet and infused with angiotensin II (Ang II) together with different PAI-1 variants, including PAI-1AK (AK) that inhibits plasminogen activators but does not bind vitronectin, PAI-1RR (RR) that binds vitronectin but does not have protease inhibitory effects or control PAI-1 (CPAI), the control mutant that has similar molecular backbone and half-life as AK and RR while retaining all functions of native PAI-1. Compared with RR and CPAI, non-vitronectin-binding AK significantly increased expression of cardiac fibroblast marker, periostin (Ang+AK 8.40±3.55 vs Ang+RR 2.23±0.44 and Ang+CPAI 2.33±0.12% positive area, both P<0.05) and cardiac fibrosis (Ang+AK 1.79±0.26% vs Ang+RR 0.91±0.18% and Ang+CPAI 0.81±0.12% fibrotic area, both P<0.05), as well as Col1 mRNA (Ang+AK 12.81±1.84 vs Ang+RR 4.04±1.06 and Ang+CPAI 5.23±1.21 fold increase, both P<0.05). To elucidate mechanisms underlying the protective effects of vitronectin-binding PAI-1 against fibrosis, fibroblasts from normal adult human ventricles were stimulated with Ang and different PAI-1 variants. Protease inhibitory AK and CPAI increased supernatant fibronectin, while decreasing plasminogen activator/plasmin activities and matrix metalloproteinase. RR and CPAI variants significantly reduced fibroblast expression of integrin β3, vitronectin level in the supernatant and fibroblast adhesion to vitronectin compared with the non-vitronectin-binding AK. Further, RR and CPAI preserved apoptotic, decreased anti-apoptotic and proliferative activities in fibroblasts. Thus, PAI-1 promotes or protects against development of cardiac fibrosis differentially through the protease inhibitory pathway or through its binding to vitronectin.
authors.affiliation: 1] Department of Pediatrics, Vanderbilt University Medical Center, Nashville, TN, USA [2] Division of Nephrology, Huashan Hospital, Fudan University, Shanghai, China.
authors.forename: Jianyong
authors.initials: J
authors.lastname: Zhong
authors.affiliation: Departments of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN, USA.
authors.forename: Hai-Chun
authors.initials: HC
authors.lastname: Yang
authors.affiliation: Department of Pediatrics, Vanderbilt University Medical Center, Nashville, TN, USA.
authors.forename: Valentina
authors.initials: V
authors.lastname: Kon
authors.affiliation: 1] Department of Pediatrics, Vanderbilt University Medical Center, Nashville, TN, USA [2] Departments of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN, USA.
authors.forename: Agnes B
authors.initials: AB
authors.lastname: Fogo
authors.affiliation: Department of Internal Medicine, University of Michigan, Ann Arbor, MI, USA.
authors.forename: Daniel A
authors.initials: DA
authors.lastname: Lawrence
authors.affiliation: Department of Pediatrics, Vanderbilt University Medical Center, Nashville, TN, USA.
authors.forename: Ji
authors.initials: J
authors.lastname: Ma
mesh_terms: D000704:Analysis of Variance; D000804:Angiotensin II; D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D002465:Cell Movement; D049109:Cell Proliferation / Q000187:drug effects; D005260:Female; D005340:Fibrinogen / Q000378:metabolism; D005341:Fibrinolysin / Q000378:metabolism; D005347:Fibroblasts / Q000187:drug effects* / Q000378:metabolism; D005355:Fibrosis / Q000378:metabolism*; D006352:Heart Ventricles; D006801:Humans; D051379:Mice; D008810:Mice, Inbred C57BL; D009206:Myocardium / Q000473:pathology*; D017395:Plasminogen Activator Inhibitor 1 / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D019096:Vitronectin / Q000378:metabolism*
chemical_list: D017395:Plasminogen Activator Inhibitor 1; D019096:Vitronectin; D000804:Angiotensin II; D005340:Fibrinogen; D005341:Fibrinolysin