Neutrophil Elastase Differentially Regulates Interleukin 8 (IL-8) and Vascular Endothelial Growth Factor (VEGF) Production by Cigarette Smoke Extract.

Inflammation by IL-8-induced neutrophil recruitment and apoptosis of epithelial cells by decreased expression of VEGF have been suggested as one of the complicated pathogenic mechanisms of chronic obstructive pulmonary disease (COPD). The role of neutrophil elastase (NE) in the development of COPD is also well known. However, little is known about how they interact. The objective of this study was to elucidate the effect of NE on cigarette smoke extract (CSE)-induced IL-8 and VEGF production and its molecular mechanism in bronchial epithelial cells. CSE increased both IL-8 and VEGF production in human bronchial epithelial cells (BEAS-2B). Although NE significantly enhanced CSE-induced IL-8 production, it suppressed VEGF production. This differential regulation was not CSE-specific. The effect of NE on IL-8 production, but not VEGF, was ERK-dependent. Interestingly, in contrast to decreased VEGF protein expression, NE accelerated VEGF transcription by CSE, suggesting post-translational modification. When cells were incubated with purified NE, it was detected in the cytoplasm, suggesting the intracellular translocation of NE. Furthermore, NE fragmented recombinant human VEGF in vitro but not recombinant human IL-8. These results indicate that VEGF down-regulation is due to direct degradation by NE, which is translocated into cells. Similar to in vitro cell experiments, elastase treatment increased CSE-induced IL-8; however, it suppressed VEGF production in bronchoalveolar lavage fluid of CSE-treated mice. Moreover, elastase treatment enhanced CSE-induced emphysema in mice. Considering the actions of IL-8 and VEGF, our results suggest that NE contributes to the pathogenesis of COPD by enhancing inflammation and apoptosis.

Lee KH ，Lee CH ，Jeong J ，Jang AH ，Yoo CG ... -  《-》

Cigarette smoke extract enhances neutrophil elastase-induced IL-8 production via proteinase-activated receptor-2 upregulation in human bronchial epithelial cells.

Lee KH ，Lee J ，Jeong J ，Woo J ，Lee CH ，Yoo CG ... -  《-》

Exogenous neutrophil elastase enters bronchial epithelial cells and suppresses cigarette smoke extract-induced heme oxygenase-1 by cleaving sirtuin 1.

An imbalance between oxidative stress and antioxidant activity plays an important role in the pathogenesis of chronic obstructive pulmonary disease (COPD). Cigarette smoke, a major risk factor of COPD, induces cellular oxidative stress, but levels of antioxidants such as heme oxygenase-1 (HO-1) are reduced in individuals with severe COPD. In this study, we evaluated the molecular mechanism of reduced HO-1 expression in human bronchial epithelial cells. We found that cigarette smoke extract (CSE) increases HO-1 levels via activation of NFE2-related factor 2 (Nrf2). However, pretreating cells with the protease neutrophil elastase (NE) suppressed the CSE-induced expression of HO-1 mRNA and protein. NE also decreased the sirtuin 1 (SIRT1) level, but did not inhibit CSE-induced nuclear translocation and DNA-binding activity of Nrf2. Transfection of cells with a Myc/His-tagged SIRT1 expression vector completely blocked the NE-mediated suppression of HO-1 expression. We further noted that the NE-induced down-regulation of SIRT1 was not due to decreased transcription or proteasomal/lysosomal degradation or loss of solubility. Immunofluorescence staining revealed that NE enters the cell cytoplasm, and we observed that NE directly cleaved SIRT1 in vitro, indicating that SIRT1 levels are decreased via direct degradation by internalized NE. Of note, we observed decreased SIRT1 levels in NE-treated primary human bronchial epithelial cells and in lung homogenates from both smokers and patients with COPD. In conclusion, NE suppresses CSE-induced HO-1 expression by cleaving SIRT1. This finding indicates the importance of cross-talk between oxidative stress and protease responses in the pathogenesis of COPD.

Lee KH ，Jeong J ，Koo YJ ，Jang AH ，Lee CH ，Yoo CG ... -  《-》

Inhibition of neutrophil elastase prevents cigarette smoke exposure-induced formation of neutrophil extracellular traps and improves lung function in a mouse model of chronic obstructive pulmonary disease.

Chronic obstructive pulmonary disease (COPD) is an important public health challenge worldwide, and is usually caused by significant exposure to noxious agents, particularly cigarette smoke. Recent studies have revealed that excessive production of neutrophil extracellular traps (NETs) in the airways is associated with disease severity in COPD patients. NETs are extracellular neutrophil-derived structures composed of chromatin fibers decorated with histones and granule proteases including neutrophil elastase (NE). However, the effective prevention of NET formation in COPD remains elusive. Here, we demonstrated that treatment with GW311616A, a potent and selective inhibitor of NE, prevented cigarette smoke extract (CSE)-induced NET formation in human neutrophils by blocking NE nuclear translocation and subsequent chromatin decondensation. Inhibition of NE also abrogated CSE-induced ROS production and migration impairment of neutrophils. Administration of GW311616A in vivo substantially reduced pulmonary generation of NETs while attenuating the key pathological changes in COPD, including airway leukocyte infiltration, mucus-secreting goblet cell hyperplasia, and emphysema-like alveolar destruction in a mouse model of COPD induced by chronic cigarette smoke exposure. Mice treated with GW311616A also showed significant attenuation of neutrophil numbers and percentages and the levels of neutrophil chemotactic factors (LTB4, KC, and CXCL5) and proinflammatory cytokines (IL-1β, and TNF-α) in bronchoalveolar lavage fluid compared to mice treated with cigarette smoke exposure only. Furthermore, GW311616A treatment considerably improved lung function in the COPD mouse model, including preventing the decline of FEV100/FVC and delta PEF as well as inhibiting the increase in FRC, TLC, and FRC/TLC. Overall, our study suggests that NE plays a critical role in cigarette smoke-induced NET formation by neutrophils and that inhibition of NE is a promising strategy to suppress NET-mediated pathophysiological changes in COPD.

Wang K ，Liao Y ，Li X ，Wang R ，Zeng Z ，Cheng M ，Gao L ，Xu D ，Wen F ，Wang T ，Chen J ... -  《-》

Primary human alveolar type II epithelial cell chemokine release: effects of cigarette smoke and neutrophil elastase.

Witherden IR ，Vanden Bon EJ ，Goldstraw P ，Ratcliffe C ，Pastorino U ，Tetley TD ... -  《-》