title: Annexin A2 contributes to lung injury and fibrosis by augmenting factor Xa fibrogenic activity.
abstract: In lung injury and disease, including idiopathic pulmonary fibrosis (IPF), extravascular factor X is converted into factor Xa (FXa), a coagulant protease with fibrogenic actions. Extracellular annexin A2 binds to FXa, augmenting activation of the protease-activated receptor-1 (PAR-1). In this study, the contribution of annexin A2 in lung injury and fibrosis was investigated. Annexin A2 immunoreactivity was observed in regions of fibrosis, including those associated with fibroblasts in lung tissue of IPF patients. Furthermore, annexin A2 was detected in the conditioned media and an EGTA membrane wash of human lung fibroblast (LF) cultures. Incubation with human plasma (5% vol/vol) or purified FXa (15-50 nM) evoked fibrogenic responses in LF cultures, with FXa increasing interleukin-6 (IL-6) production and cell number by 270 and 46%, respectively (P< 0.05,n= 5-8). The fibrogenic actions of plasma or FXa were attenuated by the selective FXa inhibitor apixaban (10 μM, or antibodies raised against annexin A2 or PAR-1 (2 μg/ml). FXa-stimulated LFs from IPF patients (n= 6) produced twice as much IL-6 as controls (n= 10) (P< 0.05), corresponding with increased levels of extracellular annexin A2. Annexin A2 gene deletion in mice reduced bleomycin-induced increases in bronchoalveolar lavage fluid (BALF) IL-6 levels and cell number (*P< 0.05;n= 4-12). Lung fibrogenic gene expression and dry weight were reduced by annexin A2 gene deletion, but lung levels of collagen were not. Our data suggest that annexin A2 contributes to lung injury and fibrotic disease by mediating the fibrogenic actions of FXa. Extracellular annexin A2 is a potential target for the treatment of IPF.
authors.affiliation: Lung Health Research Centre, Department of Pharmacology and Therapeutics, University of Melbourne, Parkville, Victoria, Australia; michael.schuliga@newcastle.edu.au.|School of Biomedical Sciences and Pharmacy, University of Newcastle, Callaghan, New South Wales, Australia.|Priority Research Centre for Healthy Lungs, Hunter Medical Research Institute, New Lambton Heights, New South Wales, Australia.
authors.forename: Michael
authors.identifier: 0000-0001-6742-5028
authors.initials: M
authors.lastname: Schuliga
authors.affiliation: Department of Allergy, Immunology, and Respiratory Medicine, Alfred Hospital, Prahran, Victoria, Australia.
authors.forename: Jade
authors.initials: J
authors.lastname: Jaffar
authors.affiliation: Lung Health Research Centre, Department of Pharmacology and Therapeutics, University of Melbourne, Parkville, Victoria, Australia.
authors.forename: Asres
authors.initials: A
authors.lastname: Berhan
authors.affiliation: Lung Health Research Centre, Department of Pharmacology and Therapeutics, University of Melbourne, Parkville, Victoria, Australia.
authors.forename: Shenna
authors.initials: S
authors.lastname: Langenbach
authors.affiliation: Lung Health Research Centre, Department of Pharmacology and Therapeutics, University of Melbourne, Parkville, Victoria, Australia.
authors.forename: Trudi
authors.initials: T
authors.lastname: Harris
authors.affiliation: School of Biomedical Sciences and Pharmacy, University of Newcastle, Callaghan, New South Wales, Australia.|Priority Research Centre for Healthy Lungs, Hunter Medical Research Institute, New Lambton Heights, New South Wales, Australia.
authors.forename: David
authors.initials: D
authors.lastname: Waters
authors.affiliation: Department of Mechanical Engineering, University of Melbourne, Parkville, Victoria, Australia.
authors.forename: Peter V S
authors.initials: PVS
authors.lastname: Lee
authors.affiliation: Priority Research Centre for Healthy Lungs, Hunter Medical Research Institute, New Lambton Heights, New South Wales, Australia.|School of Medicine and Public Health, University of Newcastle, Callaghan, New South Wales, Australia; and.
authors.forename: Christopher
authors.initials: C
authors.lastname: Grainge
authors.affiliation: Department of Allergy, Immunology, and Respiratory Medicine, Alfred Hospital, Prahran, Victoria, Australia.
authors.forename: Glen
authors.initials: G
authors.lastname: Westall
authors.affiliation: School of Biomedical Sciences and Pharmacy, University of Newcastle, Callaghan, New South Wales, Australia.|Priority Research Centre for Healthy Lungs, Hunter Medical Research Institute, New Lambton Heights, New South Wales, Australia.|Department of Anesthesiology, Pharmacology, and Therapeutics, University of British Columbia, Vancouver, British Columbia, Canada.
authors.forename: Darryl
authors.initials: D
authors.lastname: Knight
authors.affiliation: Lung Health Research Centre, Department of Pharmacology and Therapeutics, University of Melbourne, Parkville, Victoria, Australia.
authors.forename: Alastair G
authors.initials: AG
authors.lastname: Stewart
mesh_terms: D000818:Animals; D017306:Annexin A2 / Q000378:metabolism*; D001761:Bleomycin; D049109:Cell Proliferation; D015951:Factor Xa / Q000378:metabolism*; D005347:Fibroblasts / Q000378:metabolism / Q000473:pathology; D017353:Gene Deletion; D006801:Humans; D007150:Immunohistochemistry; D015850:Interleukin-6 / Q000378:metabolism; D008168:Lung / Q000473:pathology; D055370:Lung Injury / Q000097:blood / Q000150:complications / Q000378:metabolism* / Q000473:pathology*; D020935:MAP Kinase Signaling System; D008810:Mice, Inbred C57BL; D011658:Pulmonary Fibrosis / Q000097:blood / Q000150:complications / Q000378:metabolism* / Q000473:pathology*; D044463:Receptor, PAR-1 / Q000378:metabolism
chemical_list: D017306:Annexin A2; D015850:Interleukin-6; D044463:Receptor, PAR-1; D001761:Bleomycin; D015951:Factor Xa
keywords: apixaban; extracellular-regulated kinase; idiopathic pulmonary fibrosis; interstitial lung disease; protease activated receptor-1