Human airway trypsin-like protease stimulates human bronchial fibroblast proliferation in a protease-activated receptor-2-dependent pathway

• Published in: American journal of physiology. Lung cellular and molecular physiology 2006-02, Vol.290 (2), p.L385-L395
• Main Authors: Matsushima, Rie, Takahashi, Akira, Nakaya, Yutaka, Maezawa, Hiroshi, Miki, Mari, Nakamura, Yoichi, Ohgushi, Fumitaka, Yasuoka, Susumu
• Format: Article
• Language: English
• Subjects: Aged; Bronchi - cytology; Butadienes - pharmacology; Calcium - metabolism; Cell Proliferation - drug effects; Chromatography, Gel; DNA - biosynthesis; Fibroblasts - cytology; Fibroblasts - enzymology; Humans; Leupeptins - pharmacology; Lung - cytology; MAP Kinase Signaling System - drug effects; MAP Kinase Signaling System - physiology; Middle Aged; Nitriles - pharmacology; Receptor, PAR-2 - biosynthesis; Receptor, PAR-2 - immunology; Receptor, PAR-2 - physiology; Serine Endopeptidases - isolation & purification; Serine Endopeptidases - metabolism; Serine Endopeptidases - pharmacology; Sputum - metabolism; Tryptases
• ISSN: 1040-0605; 1522-1504
• DOI: 10.1152/ajplung.00098.2005

1 Department of Nutrition and Metabolism, Graduate School of Nutrition and Bioscience, and 2 Department of Medical Sciences, School of Medicine, University of Tokushima, Tokushima; and 3 Department of Clinical Investigation, National Hospital Organization, Kochi National Hospital, Kochi City, Japan Submitted 2 March 2005 ; accepted in final form 21 September 2005 Human airway trypsin-like protease (HAT) was isolated from airway secretions and localized to bronchial epithelial cells by immunohistochemistry. In the present study, we examined whether HAT could stimulate DNA synthesis and proliferation of primary human bronchial fibroblasts (HBF). HAT significantly stimulated the proliferation of HBF by 20–55%, a level similar to that of the mitogenic activity of lung mast cell tryptase (MCT). HAT also stimulated the incorporation of [ 3 H]thymidine in HBF, and this HAT-induced DNA synthesis was abolished by leupeptin. Protease-activated receptor-2 (PAR-2) mRNA was expressed and localized to the cell surface in HBF. PAR-2 activating peptide (AP) also enhanced DNA synthesis, and both HAT and PAR-2 AP induced receptor internalization, similar to the response to trypsin. Pretreatment of HBF with anti-PAR-2 antibody significantly suppressed both HAT and PAR-2 AP-induced DNA synthesis. In addition, HAT and PAR-2 AP induced intracellular Ca 2+ mobilization in HBF. The HAT-induced increase in Ca 2+ was desensitized by pretreatment with trypsin or PAR-2 AP. U0126, a specific MAPK inhibitor, completely inhibited HAT-induced DNA synthesis as well as HAT-induced phosphorylation of MAPK. The effect of HAT and MCT together was additive, whereas the effect of HAT and insulin together on HBF DNA synthesis was synergistic. These results indicate that HAT stimulates fibroblast proliferation in bronchial airways through a PAR-2-dependent MEK-MAPK mediated pathway and that HAT is linked to airway processes involving fibroblasts. mast cell tryptase; mitogen-activated protein kinase Address for reprint requests and other correspondence: R. Matsushima, Dept. of Nutrition and Metabolism, Graduate School of Nutrition and Bioscience, Univ. of Tokushima, 3-18-15 Kuramoto-cho, Tokushima, Japan 770-8503 (e-mail: rie{at}nutr.med.tokushima-u.ac.jp )