Tissue Factor Facilitates Wound Healing in Human Airway Epithelial Cells

BACKGROUND: Tissue factor (TF) canonically functions as the initiator of the coagulation cascade. TF levels are increased in inflamed airways and seem to be important for tumor growth and metastasis. We hypothesized that airway epithelia release TF as part of a wound repair program. OBJECTIVES: The goal of this study was to evaluate whether airway epithelia release TF in response to pro-inflammatory stimuli and to investigate roles of TF in cell growth and repair. METHODS: Airway epithelial cells were exposed to 10 mu g/mL of lipopolysaccharide or 1 ng/mL of transforming growth factor beta (TGF-beta). TF and TGF-beta messenger RNA and protein were measured in cell lysate and culture media, respectively. Signaling pathways were evaluated by using selective agonists and inhibitors. Airway epithelia were mechanically injured in the presence of TF and tissue factor pathway inhibitor to investigate their roles in wound repair. RESULTS: TF protein levels increased in cell media after exposure to lipopolysaccharide (P <.01) but only in growing cells, and this action was blocked when exposed to an extracellular signal-regulated kinase inhibitor or a small worm phenotype and mothers against Decapentaplegic inhibitor. TF protein also increased in the presence of TGF-beta (P <.05). Exposure to TF pathway inhibitor decreased the rate of cell growth by 60% (P <.05), and exposure to TF increased the rate of airway healing after injury by 19% (P <.05). CONCLUSIONS: Growing airway epithelia release TF when exposed to lipopolysaccharide or TGF-beta. TF reduces wound-healing time in airway epithelia and therefore may be important to airway recovery after injury.