Erythromycin suppresses neutrophil extracellular traps in smoking-related chronic pulmonary inflammation.

Neutrophil extracellular traps (NETs) may play a critical role in smoking-related chronic airway inflammation. However, the mechanism by which NETs induced by cigarette smoke initiate the adaptive immunity in chronic obstructive pulmonary disease (COPD) is not fully understood. In this study, we explored the effects of NETs induced by cigarette smoke on the myeloid dendritic cells (mDCs) and Th1 and Th17 cells. Additionally, we observed the inhibitory effect of erythromycin on NETs induced by cigarette smoke. We found that elevated NET levels in the sputum of COPD patients were correlated with the circulating Th1 response, mDC activation and airflow limitation. NETs induced by cigarette smoke extract (CSE) could activate monocyte-derived mDCs and promote Th1 and Th17 differentiation in vitro. Erythromycin effectively inhibited NET formation induced by CSE. In vivo, erythromycin decreased NETs in the airway and ameliorated emphysema with Th1 and Th17 cell down-regulation and CD40+ and CD86+ mDCs suppression in mice chronically exposed to cigarette smoke. These findings provide direct evidence that NETs promote the differentiation of Th1 and Th17 and play a role in the adaptive immunity of smoking-related chronic lung inflammation. Erythromycin is a potential therapeutic strategy for NETs inhibition in COPD.

Enhanced activation of circulating plasmacytoid dendritic cells in patients with Chronic Obstructive Pulmonary Disease and experimental smoking-induced emphysema.

Plasmacytoid dendritic cells (pDCs) are key cells bridging the innate with adaptive immunity. However, the phenotypic characteristics of circulating pDCs and its role in smoking related-Chronic Obstructive Pulmonary Disease (COPD) remain largely unknown. The aim of this study was analyzed the phenotype of circulating pDCs and the expression of IFN-γ producing CD8+T cells and IL-17-producing CD8+T cells in patients with COPD by using multi-colour flow cytometry. The cytokine profiles in peripheral blood from all subjects were measured by ELISA. The influence of cigarette smoke on pDCs was evaluated in an experimental mouse model of emphysema. Circulating pDCs in patients with COPD and in mice exposed to cigarette smoke expressed high levels of co-stimulatory molecules CD40 or CD86 accompanied by exaggerated IFN-γ producing CD8+T cells and IL-17-producing CD8+T cells. In vitro, cigarette smoke directly promoted pDCs maturation and release of IFN-α, IL-6 and IL-12, subsequently inducing differentiation of IFN-γ producing CD8+T cells and IL-17-producing CD8+T cells from mouse naïve CD8+T cells. These data suggested that circulating pDCs display an enhanced activation phenotype in patients with COPD and in experimental smoking mouse model of emphysema, which might contribute to exaggerated IFN-γ producing CD8+T and IL-17-producing CD8+T cell-mediated immune responses.

Neutrophil extracellular traps induced by cigarette smoke activate plasmacytoid dendritic cells.

BACKGROUND: Neutrophil extracellular traps (NETs) represent a distinct strategy by which neutrophils trap, confine and eliminate invading microorganisms. Emerging evidence suggests that NETs exert a deleterious effect to the host in the absence of microbial stimuli. However, the role of NETs in smoking-related lung diseases remains to be elucidated. OBJECTIVES: To evaluate the formation of NETs in the context of chronic inflammation induced by cigarette smoking and explore its potential role in an experimental mouse model of emphysema. METHODS: The formation and degradation of NETs in cigarette smoke exposed mice was assessed with a fluorescence microscope. The potential influences of NETs on plasmacytoiddendritic cells were also investigated. RESULTS: NETs were more prone to formation by polymorphonuclearneutrophils but defective in degradation in cigarette smoke exposed mice. Cigarette smoke extract (CSE) served as an important facilitator that triggered neutrophils to undergo NETosis in vitro. Furthermore, CSE-induced NETs were capable of driving plasmacytoiddendritic cell maturation and activation, thereby initiating a T-cell-mediated immune response. CONCLUSIONS: NETs may represent a critical connection between innate and adaptive immune responses under conditions of chronic inflammation induced by cigarette smoke exposure.