Mast Cell Tryptase Enhances Wound-Healing Via Protease-Activated Receptor-2 Dependent Migration in Human Bronchial Epithelial Cells

Introduction: Epithelial damage and increase of intraepithelial mast cells (MC) are characteristics of asthma. The role of MC mediator tryptase and the protease-activated receptor-2 (PAR2) on epithelial wound healing is not fully investigated. Aim: To investigate the effect of tryptase on epithelial cell migration and proliferation in a wound gap model. Methods: Human bronchial epithelial cells (HBECs) were treated with tryptase and/or PAR2 inhibitor I-191. Gap closure, migration, migratory direction, cell speed and cell length were studied using a novel live cell imaging technique. Proliferation and migration markers were analyzed using qPCR, ELISA, Luminex and immunocytochemistry. Results: Stimulation of HBECs with tryptase promoted gap closure (P<0.01), migration (P<0.05) and cellular speed (P<0.05) compared to controls. Stimulated HBECs had higher expression of migration marker CD151 compared to controls (P<0.05). Proliferation marker KI67 was upregulated in tryptase stimulated HBECs compared to controls (P<0.01). Treatment with I-191 reduced gap closure (P<0.05), migration (P<0.0001) and cell speed (P<0.001) compared to HBECs stimulated with tryptase. Proliferation was however not significantly altered by PAR2 inhibition. Conclusion: We found that tryptase enhances epithelial wound healing by increased migration and proliferation, which is in part regulated via PAR2. Our data suggests that tryptase might be beneficial in tissue repair under baseline conditions. However, in a pathological context such as asthma with increased numbers of activated MCs, it might lead to epithelial remodelling and loss of function.