Collagen I and thrombin activate MMP-2 by MMP-14-dependent and -independent pathways: implications for airway smooth muscle migration.
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.
Henderson
Neil
N
Division of Therapeutics and Molecular Medicine, University Hospital, Queens Medical Centre, Nottingham, United Kingdom.
Markwick
Lee J
LJ
Elshaw
Shona R
SR
Freyer
Anette M
AM
Knox
Alan J
AJ
Johnson
Simon Richard
SR
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
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