title: Collagen I and thrombin activate MMP-2 by MMP-14-dependent and -independent pathways: implications for airway smooth muscle migration.
abstract: Increased proinflammatory mediators and ECM deposition are key features of the airways in asthma. Matrix metalloproteinases (MMPs) are produced by airway smooth muscle (ASM) cells and have multiple roles in inflammation and tissue remodeling. We hypothesized that components of the asthmatic airway would stimulate MMP production and activation by ASM and contribute to airway remodeling. We measured human ASM-derived MMP mRNA, protein, and activity by real-time RT-PCR, zymography, Western blotting, and MMP activity assay. Collagen I and thrombin caused a synergistic increase in MMP-2 protein and total MMP activity but paradoxically decreased MMP-2 mRNA. Additionally, collagen I activated MMP-2 in culture supernatants independent of the cell surface. Together, collagen I and thrombin strongly enhanced MMP-14 mRNA and protein but had no effect individually, suggesting increased MMP-14, the activating protease for MMP-2, may be partially responsible for MMP-2 activation. Furthermore, collagen I reduced tissue inhibitor of metalloproteinase-2 protein (TIMP-2). We examined the role of MMPs in functions of ASM related to airway remodeling and found migration and proliferation were MMP dependent, whereas adhesion and apoptosis were not. Ilomastat inhibited migration by 25%, which was also inhibited by TIMPs 1-4 and increased by the MMP-2 activator thrombin. These in vitro findings suggest that the environment within the airways of patients with asthma enhances MMP-2 and -14 protein and activity by a complex interaction of transcriptional and posttranscriptional mechanisms, which may contribute to ASM migration.
authors.affiliation: Division of Therapeutics and Molecular Medicine, University Hospital, Queens Medical Centre, Nottingham, United Kingdom.
authors.forename: Neil
authors.initials: N
authors.lastname: Henderson
authors.forename: Lee J
authors.initials: LJ
authors.lastname: Markwick
authors.forename: Shona R
authors.initials: SR
authors.lastname: Elshaw
authors.forename: Anette M
authors.initials: AM
authors.lastname: Freyer
authors.forename: Alan J
authors.initials: AJ
authors.lastname: Knox
authors.forename: Simon Richard
authors.initials: SR
authors.lastname: Johnson
mesh_terms: D002465:Cell Movement / Q000502:physiology*; D024042:Collagen Type I / Q000502:physiology*; D004789:Enzyme Activation; D006801:Humans; D053511:Matrix Metalloproteinase 14 / Q000502:physiology*; D020778:Matrix Metalloproteinase 2 / Q000378:metabolism*; D009130:Muscle, Smooth / Q000502:physiology*; D013917:Thrombin / Q000502:physiology*; D019716:Tissue Inhibitor of Metalloproteinase-2 / Q000502:physiology; D014132:Trachea / Q000502:physiology*; D048051:p38 Mitogen-Activated Protein Kinases / Q000502:physiology
chemical_list: D024042:Collagen Type I; D019716:Tissue Inhibitor of Metalloproteinase-2; D048051:p38 Mitogen-Activated Protein Kinases; D013917:Thrombin; D020778:Matrix Metalloproteinase 2; D053511:Matrix Metalloproteinase 14