Role of aberrant metalloproteinase activity in the pro-inflammatory phenotype of bronchial epithelium in COPD

<p>Abstract</p> <p>Background</p> <p>Cigarette smoke, the major risk factor for COPD, is known to activate matrix metalloproteinases in airway epithelium. We investigated whether metalloproteinases, particularly A Disintegrin and Metalloproteinase (ADAM)17, contribute to increased pro-inflammatory epithelial responses with respect to the release of IL-8 and TGF-α, cytokines implicated in COPD pathogenesis.</p> <p>Methods</p> <p>We studied the effects of cigarette smoke extract (CSE) and metalloproteinase inhibitors on TGF-α and IL-8 release in primary bronchial epithelial cells (PBECs) from COPD patients, healthy smokers and non-smokers.</p> <p>Results</p> <p>We observed that TGF-α was mainly shed by ADAM17 in PBECs from all groups. Interestingly, IL-8 production occurred independently from ADAM17 and TGF-α shedding, but was significantly inhibited by broad-spectrum metalloproteinase inhibitor TAPI-2. CSE did not induce ADAM17-dependent TGF-α shedding, while it slightly augmented the production of IL-8. This was accompanied by reduced endogenous inhibitor of metalloproteinase (TIMP)-3 levels, suggesting that CSE does not directly but rather indirectly alter activity of ADAM17 through the regulation of its endogenous inhibitor. Furthermore, whereas baseline TGF-α shedding was lower in COPD PBECs, the early release of IL-8 (likely due to its shedding) was higher in PBECs from COPD than healthy smokers. Importantly, this was accompanied by lower TIMP-2 levels in COPD PBECs, while baseline TIMP-3 levels were similar between groups.</p> <p>Conclusions</p> <p>Our data indicate that IL-8 secretion is regulated independently from ADAM17 activity and TGF-α shedding and that particularly its early release is differentially regulated in PBECs from COPD and healthy smokers. Since TIMP-2-sensitive metalloproteinases could potentially contribute to IL-8 release, these may be interesting targets to further investigate novel therapeutic strategies in COPD.</p

Lycopene Inhibits NF-kB-Mediated IL-8 Expression and Changes Redox and PPARγ Signalling in Cigarette Smoke–Stimulated Macrophages

Increasing evidence suggests that lycopene, the major carotenoid present in tomato, may be preventive against smoke-induced cell damage. However, the mechanisms of such a prevention are still unclear. The aim of this study was to investigate the role of lycopene on the production of the pro-inflammatory cytokine IL-8 induced by cigarette smoke and the possible mechanisms implicated. Therefore, human THP-1 macrophages were exposed to cigarette smoke extract (CSE), alone and following a 6-h pre-treatment with lycopene (0.5–2 µM). CSE enhanced IL-8 production in a time- and a dose-dependent manner. Lycopene pre-treatment resulted in a significant inhibition of CSE-induced IL-8 expression at both mRNA and protein levels. NF-kB controlled the transcription of IL-8 induced by CSE, since PDTC prevented such a production. Lycopene suppressed CSE-induced NF-kB DNA binding, NF-kB/p65 nuclear translocation and phosphorylation of IKKα and IkBα. Such an inhibition was accompanied by a decrease in CSE-induced ROS production and NOX-4 expression. Lycopene further inhibited CSE-induced phosphorylation of the redox-sensitive ERK1/2, JNK and p38 MAPKs. Moreover, the carotenoid increased PPARγ levels which, in turn, enhanced PTEN expression and decreased pAKT levels in CSE-exposed cells. Such effects were abolished by the PPARγ inhibitor GW9662. Taken together, our data indicate that lycopene prevented CSE-induced IL-8 production through a mechanism involving an inactivation of NF-kB. NF-kB inactivation was accompanied by an inhibition of redox signalling and an activation of PPARγ signalling. The ability of lycopene in inhibiting IL-8 production, NF-kB/p65 nuclear translocation, and redox signalling and in increasing PPARγ expression was also found in isolated rat alveolar macrophages exposed to CSE. These findings provide novel data on new molecular mechanisms by which lycopene regulates cigarette smoke-driven inflammation in human macrophages

Estudo imunohistoquímico do remodelamento pulmonar em camundongos expostos à fumaça de cigarro Immunohistochemical study of lung remodeling in mice exposed to cigarette smoke

OBJETIVO: Muitos estudos sobre enfisema são realizados com exposição de animais à fumaça de cigarro durante um longo tempo, focando o tipo de célula envolvida no desequilíbrio protease/antiprotease e a degradação da matriz extracelular. A expressão aumentada de metaloproteinases no enfisema está associado com citocinas e evidências sugerem um papel importante da metaloproteinase de matriz-12 (MMP-12). Nosso objetivo foi estudar a detecção de inibidor tissular de metaloproteinase-2 (TIMP-2), fator de necrose tumoral alfa (TNF-&#945;) e interleucina-6 (IL-6) por métodos imunohistoquímicos no pulmão de camundongos. MÉTODOS: Camundongos C57BL/6 machos foram expostos 3 vezes ao dia a fumaça de 3 cigarros por um período de 10, 20, 30 ou 60 dias através de uma câmara de inalação (grupos CS10, CS20, CS30 e CS60, respectivamente). O grupo controle foi exposto às mesmas condições ao ar ambiente. RESULTADOS: Nós observamos um aumento progressivo de macrófagos alveolares no lavado broncoalveolar dos grupos expostos. O diâmetro alveolar médio, um indicador de destruição alveolar, aumentou em todos os grupos expostos quando comparado ao grupo controle. O índice imunohistoquímico (II) para MMP-12 aumentou nos grupos CS10, CS20 e CS30 em paralelo a uma redução do II para TIMP-2 nos grupos CS10, CS20 e CS30. O II para as citocinas TNF-&#945; e IL-6 aumentou em todos os grupos expostos quando comparado ao grupo controle. Enfisema foi observado no grupo CS60, com alterações na densidade de volume de fibras colágenas e elásticas. CONCLUSÕES: Estes achados sugerem que a fumaça de cigarro induz enfisema com uma participação importante do TNF-&#945; e da IL-6 sem a participação de neutrófilos.<br>OBJECTIVE: Various studies of emphysema involve long-term exposure of animals to cigarette smoke, focusing on the cell type involved in the protease/antiprotease imbalance and on extracellular matrix degradation. In emphysema, increased expression of metalloproteinases is associated with cytokines, and evidence suggests that the matrix metalloproteinase-12 (MMP-12) plays an important role. Our objective was to investigate tissue inhibitor of metalloproteinase-2 (TIMP-2), tumor necrosis factor-alpha (TNF-&#945;) and interleukin-6 (IL-6) detection by immunohistochemical methods in mouse lung. METHODS: Male C57BL/6 mice were exposed 3 times a day to smoke of 3 cigarettes over a period of 10, 20, 30 or 60 days in an inhalation chamber (groups CS10, CS20, CS30 and CS60, respectively). Controls were exposed to the same conditions in room air. RESULTS: A progressive increase in the number of alveolar macrophages was observed in the bronchoalveolar lavage fluid of the exposed mice. The mean linear intercept, an indicator of alveolar destruction, was greater in all exposed groups when compared to control group. In the CS10, CS20 and CS30 mice, the immunohistochemical index (II) for MMP-12 increased in parallel with a decrease in II for TIMP-2 in the CS10, CS20 and CS30 mice. The II for the cytokines TNF-&#945; and IL-6 was greater in all exposed groups than in the control group. Emphysema, with changes in volume density of collagen and elastic fibers, was observed in the CS60 group. CONCLUSIONS: These findings suggest that cigarette smoke induces emphysema with major participation of TNF-&#945; and IL-6 without participation of neutrophils