title: Matrix metalloproteinase expression and activity in human airway smooth muscle cells.
abstract: Airway remodelling is a feature of chronic asthma comprising smooth muscle hypertrophy and deposition of extracellular matrix (ECM) proteins. Matrix metalloproteinases (MMPs) breakdown ECM, are involved in tissue remodelling and have been implicated in airway remodelling. Although mesenchymal cells are an important source of MMPs, little data are available on airway smooth muscle (ASM) derived MMPs. We therefore investigated MMP and tissue inhibitor of metalloproteinase (TIMP) production and activity in human ASM cells. MMPs and TIMPs were examined using quantitative real-time RT-PCR, Western blotting, zymography and a quench fluorescence (QF) assay of total MMP activity. The most abundant MMPs were pro-MMP-2, pro- MMP-3, active MMP-3 and MT1-MMP. TIMP-1 and TIMP-2 expression was low in cell lysates but high in conditioned medium. High TIMP secretion was confirmed by the ability of ASM-conditioned medium to inhibit recombinant MMP-2 in a QF assay. Thrombin increased MMP activity by activation of pro-MMP-2 independent of the conventional smooth muscle thrombin receptors PAR 1 and 4. In conclusion, ASM cells express pro-MMP-2, pro and active MMP-3, MMP-9 and MT1-MMP. Unstimulated cells secrete excess TIMP 1 and 2, preventing proteolytic activity. MMP-2 can be activated by thrombin which may contribute to airway remodelling.
authors.affiliation: Division of Therapeutics and Molecular Medicine, University of Nottingham, University Hospital, Queens Medical Centre, Nottingham NG7 2UH.
authors.forename: Shona R
authors.initials: SR
authors.lastname: Elshaw
authors.forename: Neil
authors.initials: N
authors.lastname: Henderson
authors.forename: Alan J
authors.initials: AJ
authors.lastname: Knox
authors.forename: Susan A
authors.initials: SA
authors.lastname: Watson
authors.forename: David J
authors.initials: DJ
authors.lastname: Buttle
authors.forename: Simon R
authors.initials: SR
authors.lastname: Johnson
mesh_terms: D045744:Cell Line, Tumor; D002478:Cells, Cultured; D017077:Culture Media, Conditioned / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects / Q000502:physiology*; D006801:Humans; D061965:Matrix Metalloproteinase Inhibitors; D020782:Matrix Metalloproteinases / Q000096:biosynthesis* / Q000235:genetics; D032389:Myocytes, Smooth Muscle / Q000187:drug effects / Q000201:enzymology*; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D014132:Trachea / Q000187:drug effects / Q000201:enzymology*
chemical_list: D017077:Culture Media, Conditioned; D061965:Matrix Metalloproteinase Inhibitors; D012333:RNA, Messenger; D020782:Matrix Metalloproteinases