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Background: The elastolytic enzyme matrix metalloproteinase (MMP)-12 has been implicated in the development of airway inflammation and remodeling. We investigated whether human airway smooth muscle cells could express and secrete MMP-12, thereby participating in the pathogenesis of airway inflammatory diseases. Methods: Laser capture microdissection was used to collect smooth muscle cells from human bronchial biopsy sections. MMP-12 mRNA expression was analysed by quantitative real-time RT-PCR. MMP-12 protein expression and secretion from cultured primary airway smooth muscle cells was further analysed by Western blot. MMP-12 protein localization in bronchial tissue sections was detected by immunohistochemistry. MMP-12 activity was determined by zymography. The TransAM AP-1 family kit was used to measure c-Jun activation and nuclear binding. Analysis of variance was used to determine statistical significance. Results: We provide evidence that MMP-12 mRNA and protein are expressed by in-situ human airway smooth muscle cells obtained from bronchial biopsies of normal volunteers, and of patients with asthma, COPD and chronic cough. The pro-inflammatory cytokine, interleukin (IL)-1β, induced a >100-fold increase in MMP-12 gene expression and a >10-fold enhancement in MMP-12 activity of primary airway smooth muscle cell cultures. Selective inhibitors of extracellular signal-regulated kinase, c-Jun N-terminal kinase and phosphatidylinositol 3-kinase reduced the activity of IL-1β on MMP-12, indicating a role for these kinases in IL-1β-induced induction and release of MMP-12. IL-1β-induced MMP-12 activity and gene expression was down-regulated by the corticosteroid dexamethasone but up-regulated by the inflammatory cytokine tumour necrosis factor (TNF)-α through enhancing activator protein-1 activation by IL-1β. Transforming growth factor-β had no significant effect on MMP-12 induction. Conclusion: Our findings indicate that human airway smooth muscle cells express and secrete MMP-12 that is up-regulated by IL-1β and TNF-α. Bronchial smooth muscle cells may be an important source of elastolytic activity, thereby participating in remodeling in airway diseases such as COPD and chronic asthma. [ABSTRACT FROM AUTHOR]

1 Chronic cellular inflammation and airway wall remodelling with subepithelial fibrosis and airway smooth muscle (ASM ) cell hyperplasia are features of chronic asthma. Jun N-terminal kinase (JNK) may be implicated in these processes by regulating the transcriptional activity of activator protein (AP)-l. 2 We examined the effects of an inhibitor of JNK. SP600125 (anthra [1.9-cd] pyrazole-6 (2 H)-one), in a model of chronic allergic inflammation in the rat. 3 Rats sensitised to ovalbumin (OA) were exposed to OA-aerosol every third day on six occasions and were treated with SP600I25 (30 mg kg[sup-1] b.i.d: 360mg in total )for 12 days, starting after the second through to the sixth OA exposure. We measured eosinoplhilic and T-cell inflammation in the airways. proliferation of ASM cells and epithelial cells by incorporation of bromodeoxyuridine (BrdU). and bronchial responsiveness to acetylcholine. 4 SP600125 significantly reduced the number of eosinophils (P<0.05) and lymphocytes (P<0.05) in bronchoalveolar lavage fluid. suppressed eosinophilic (P⁢0.05) and CD2 T-cell (P⁢0.05) infiltration within the bronchial submucosa. and the increased UNA incorporation in ASM (P⁢0.05) and epithelial cell incorporation (P⁢0.05). 5 SPM600125 did not alter bronchial hyper-responsiveness observed after chronic allergen exposure. 6 Pathways regulated by JNK positively regulate ASM cell proliferation and allergic cellular inflammation following chronic allergen exposure. [ABSTRACT FROM AUTHOR]

Studies the role of the mitogen-acivated protein kinase c-jun N-terminal kinase in the induced release of granulocyte-macrophage colony stimulating factor, RANTES and interleukin-8 from human airway smooth muscle cells. Intracellular signal pathway underlying the production of cytokines; Interleukin-8 phosphorylation.

Background: Exacerbations represent an important feature of the clinical manifestation and natural history of chronic obstructive pulmonary disease (COPD). Nuclear localisation of p65 is a signal of nuclear factor-kappaB (NF-kappaB) activation. A study was undertaken to evaluate whether NF-kappaB activation is modified in sputum cells during COPD exacerbations.Methods: Total and nuclear p65 immunoreactivity was measured by immunocytochemistry in the sputum cells of 11 smokers with moderate COPD during an exacerbation and after 6-8 weeks of clinical stability.Results: Total sputum cell count was significantly increased during exacerbations from a median (IQR) of 880 (510-1865) to 1914.5 (1065-3205) x 10(3)/ml (p<0.05). The main inflammatory cells in the sputum were neutrophils (83.2 (75.4-92.3)%) and macrophages (14.7 (2.6-21.6)%) and their relative proportion did not change during exacerbations. Nuclear staining for p65 was absent in sputum neutrophils, both during exacerbations and in the stable phase. In contrast, the percentage of macrophages expressing nuclear p65 increased significantly during exacerbations from a median (IQR) of 16 (7-24)% to 41.4 (6-69)% (p<0.05).Conclusions: NF-kappaB appears to be activated in sputum macrophages but not in sputum neutrophils during exacerbations of COPD [ABSTRACT FROM AUTHOR]