HMGB1 Activates Myeloid Dendritic Cells by Up-Regulating mTOR Pathway in Systemic Lupus Erythematosus.

Research has shown that HMGB1 can activate dendritic cells (DCs), but its molecular mechanisms are not clear. In this study, we reported that the myeloid dendritic cells (mDCs) were activated in the peripheral blood of SLE patients, and the activation of mDCs was associated with the up-regulation of HMGB1 and mTOR. After stimulated by HMGB1, expression of mTOR and its substrates P70S6K and 4EBP1 in dendritic cells increased considerably (P < 0.01). The expression of HLA-DR, CD40, and CD86 on dendritic cells also significantly increased following these stimuli (P < 0.01). In addition, stimulation with HMGB1 enhanced cytokine (IL-1ß, IL-6, and TNF-a) production in dendritic cells. In contrast, the HMGB1-mediated expression of HLA-DR, CD40, and CD86 on dendritic cells and production of IL-1ß, IL-6, and TNF-α were reduced by rapamycin. Rapamycin can inhibit HMGB1-induced activation of mDCs and secretion of pro-inflammatory cytokines. These findings indicated that HMGB1activates mDCs by up-regulating the mTOR pathway in SLE.

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.

Rapamycin attenuates Tc1 and Tc17 cell responses in cigarette smoke-induced emphysema in mice.

OBJECTIVE AND DESIGN: Chronic exposure to cigarette smoke promotes airway inflammation and emphysema accompanied by enhanced CD8+ interferon (IFN)-γ+ T(Tc1) and CD8+ interleukin (IL)-17+ T(Tc17) cell responses. The mammalian target of rapamycin (mTOR) has been involved in the pathogenesis of emphysema. Inhibiting mTOR by rapamycin has been reported to alleviate emphysema, but the mechanism is not fully understood. We aimed to explore the effect of rapamycin on Tc1 and Tc17 cell responses induced by cigarette smoke exposure. MATERIALS: Male C57BL/6 mice were exposed to cigarette smoke or room air for 24 weeks. Half of the smoke-exposed mice received rapamycin in the last 12 weeks. The severity of emphysema in those mice was evaluated by mean linear intercept (MLI), mean alveolar airspace area (MAA) and destructive index (DI). Bronchoalveolar lavage was collected and analyzed. Phosphorylated (p-) mTOR in CD8+ T cells, Tc1 and Tc17 cells were detected by flow cytometry. The relative expression of p-mTOR in lungs was determined by western blot analysis. IFN-γ and IL-17A levels were detected by enzyme-linked immunosorbent assays. IFN-γ, mTOR and RAR-related orphan receptor (ROR)γt mRNA levels were evaluated by the real-time polymerase chain reaction. RESULTS: Elevated p-mTOR expression in CD8+ T cells and lung tissue was accompanied by the enhanced Tc1 and Tc17 cell responses in lungs of mice exposed to cigarette smoke. Rapamycin reduced inflammatory cells in BALF and decreased MLI, DI and MAA in lungs. Rapamycin decreased p-mTOR expression, and down-regulation of mTOR and RORγt mRNA levels along with the attenuation of Tc1 and Tc17 cell responses in mice with emphysema. CONCLUSIONS: The mTOR was activated in CD8+ T cells accompanied by the enhanced Tc1 and Tc17 cell responses in cigarette smoke-related pulmonary inflammation. Rapamycin ameliorated emphysema and attenuated Tc1 and Tc17 cell responses probably caused by inhibiting mTOR in cigarette smoke-exposed mice.

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.