Annexin A2 contributes to lung injury and fibrosis by augmenting factor Xa fibrogenic activity

作者：Schuliga Michael; Jaffar Jade; Berhan Asres; Langenbach Shenna; Harris Trudi; Waters David; Lee Peter V S; Grainge Christopher; Westall Glen; Knight Darryl; Stewart Alastair G

来源：American Journal of Physiology - Lung Cellular and Molecular Physiology, 2017, 312(5): 1772-1782.

DOI：10.1152/ajplung.00553.2016

• apixaban
• extracellular-regulated kinase
• idiopathic pulmonary fibrosis
• interstitial lung disease
• protease activated receptor-1

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 mu M, or antibodies raised against annexin A2 or PAR-1 (2 mu g/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.

• 出版日期2017-5