IL-27 mediates anti-inflammatory effect in cigarette smoke induced emphysema by negatively regulating IFN-γ producing cytotoxic CD8+ T cells in mice.

Chronic airway inflammation mediated by CD8+ T lymphocytes contributes to the pathogenesis of Chronic obstructive pulmonary disease (COPD). Deciphering the fingerprint of the chronic inflammation orchestrated by CD8+ T cells may allow the development of novel approaches to COPD management. Here, the expression of IL-27 and IFN-γ+ CD8+ Tc1 cells were evaluated in patients with COPD and in cigarette smoke-exposed mice. The production of IL-27 by marrow-derived dendritic cells (mDCs) in response to cigarette smoke extract (CSE) was assessed. The role of IL-27 in IFN-γ+ CD8+ Tc1 cells was explored. We demonstrated that elevated IL-27 was accompanied by an exaggerated IFN-γ+ CD8+ Tc1 response in a smoking mouse model of emphysema. We noted that lung dendritic cells were one of the main sources of IL-27 during chronic cigarette smoke exposure. Moreover, CSE directly induced the production of IL-27 by mDCs in vitro. IL-27 negatively regulated the differentiation of IFN-γ+ CD8+ Tc1 cells isolated from cigarette smoke-exposed mice in a STAT1- and STAT3-independent manner. Systemic administration of recombinant IL-27 attenuated IFN-γ+ CD8+ Tc1 response in the late phase of cigarette smoke exposure. Our results uncovered that IL-27 negatively regulates IFN-γ+ CD8+ Tc1 response in the late stage of chronic cigarette smoke exposure, which may provide a new strategy for the anti-inflammatory treatment of smoking-related COPD/emphysema.

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.

Cigarette Smoke Induction of Interleukin-27/WSX-1 Regulates the Differentiation of Th1 and Th17 Cells in a Smoking Mouse Model of Emphysema.

IFN-γ-producing CD4+ T (Th1) cells and IL-17-producing CD4+ T (Th17) cells play a critical role in the pathogenesis of chronic obstructive pulmonary disease (COPD). However, the immune regulation between Th1 and Th17 cells remains unclear. Previous studies have demonstrated that interleukin-27 (IL-27)/WSX-1 exerted pro- or anti-inflammatory effects in many acute inflammatory diseases by modulating T cell-mediated immune response, but little was known about its role in chronic inflammatory disease, especially in smoking-related lung diseases. Considering IL-27 is an important regulator in T lymphocytes immune responses and was found markedly increased in patients with COPD, we hypothesized that IL-27/WSX-1 may exert immuno-regulatory effects on the differentiation of Th1 and Th17 cells in smoking-related COPD. In this study, we aimed to evaluate the expression of IL-27 in patients with COPD and explore the role of IL-27/WSX-1 on Th1 and Th17 cells differentiation in a smoking mouse model of emphysema. We found that elevated expression of IL-27 was associated with increased proportion of Th1 cells and Th17 cells in patients with COPD and demonstrated parallel findings in cigarette smoke-exposed mice. In addition, cigarette smoke exposure upregulated the expression of IL-27R (WSX-1) by naive CD4+ T cells in mice. In vitro, IL-27 significantly augmented the secretion of IFN-γ by naive CD4+ T cells via a T-bet, p-STAT1, and p-STAT3-dependent manner, but inhibited the production of IL-17 by a ROR-γt and p-STAT1-dependent way. Furthermore, anti-IL27 treatment dramatically decreased the expression of IFN-γ-producing CD4+ T cells in cigarette smoke-exposed mice. These findings proposed that IL-27 has functions for promoting the expression of Th1 cells but inhibiting the expression of Th17 cells in vitro and IL-27 neutralization-attenuated Th1-mediated inflammation in vivo, suggesting targeting IL-27/WSX-1 may provide a new therapeutic approach for smoking-related COPD.

Dendritic cells induce Tc1 cell differentiation via the CD40/CD40L pathway in mice after exposure to cigarette smoke.

Dendritic cells and CD8(+) T cells participate in the pathology of chronic obstructive pulmonary disease, including emphysema, but little is known of the involvement of the CD40/CD40L pathway. We investigated the role of the CD40/CD40L pathway in Tc1 cell differentiation induced by dendritic cells in a mouse model of emphysema, and in vitro. C57BL/6J wild-type and CD40(-/-) mice were exposed to cigarette smoke (CS) or not (control), for 24 wk. In vitro experiments involved wild-type and CD40(-/-) dendritic cells treated with CS extract (CSE) or not. Compared with the control groups, the CS mice (both wild type and CD40(-/-)) had a greater percentage of lung dendritic cells and higher levels of major histocompatability complex (MHC) class I molecules and costimulatory molecules CD40 and CD80. Relative to the CS CD40(-/-) mice, the CS wild type showed greater signs of lung damage and Tc1 cell differentiation. In vitro, the CSE-treated wild-type cells evidenced more cytokine release (IL-12/p70) and Tc1 cell differentiation than did the CSE-treated CD40(-/-) cells. Exposure to cigarette smoke increases the percentage of lung dendritic cells and promotes Tc1 cell differentiation via the CD40/CD40L pathway. Blocking the CD40/CD40L pathway may suppress development of emphysema in mice exposed to cigarette smoke.

Erythromycin enhances CD4+Foxp3+ regulatory T-cell responses in a rat model of smoke-induced lung inflammation.

Heavy smoking can induce airway inflammation and emphysema. Macrolides can modulate inflammation and effector T-cell response in the lungs. However, there is no information on whether erythromycin can modulate regulatory T-cell (Treg) response. This study is aimed at examining the impact of erythromycin on Treg response in the lungs in a rat model of smoking-induced emphysema. Male Wistar rats were exposed to normal air or cigarette smoking daily for 12 weeks and treated by gavage with 100 mg/kg of erythromycin or saline daily beginning at the forth week for nine weeks. The lung inflammation and the numbers of inflammatory infiltrates in bronchoalveolar lavage fluid (BALF) were characterized. The frequency, the number of Tregs, and the levels of Foxp3 expression in the lungs and IL-8, IL-35, and TNF-α in BALF were determined by flow cytometry, RT-PCR and ELISA, respectively. Treatment with erythromycin reduced smoking-induced inflammatory infiltrates, the levels of IL-8 and TNF-α in the BALF and lung damages but increased the numbers of CD4+Foxp3+ Tregs and the levels of Foxp3 transcription in the lungs, accompanied by increased levels of IL-35 in the BALF of rats. Our novel data indicated that erythromycin enhanced Treg responses, associated with the inhibition of smoking-induced inflammation in the lungs of rats.

[Change of airway inflammation induced by Th1/Tc1 and the expression of T regulatory cells in smoking cessation rats].

OBJECTIVE: to study the change of airway inflammation induced by Th1/Tc1 and the expression of CD4(+)CD25(+) regulatory T cells (Treg) in smoking cessation rats. METHODS: fifty healthy male Wistar rats were randomly divided into five groups: 12-week normal control (group A, n = 10), 24-week normal control (group B, n = 10), 12-week smoke exposure (group C, n = 10), 24-week smoke exposure (group D, n = 10) and smoking cessation (group E, n = 10). Groups C, D and E were exposed to cigarettes for 12 weeks. At Week 12, groups A and C were sacrificed. Group D continued smoke exposure and group E had smoking cessation for 12 weeks. At Week 24, groups B, D and E were sacrificed. Pathomorphological changes of small airway were analyzed. The cells in BALF (bronchoalveolar lavage fluid) were collected and analyzed by absolute and differential cell counts. Enzyme linked immunosorbent assay (ELISA) was used to detect the levels of IFN-γ, IL-4, IL-8 and TNF-α. And flow cytometry was employed to determine the Foxp3 + Treg cell populations and reverse transcription-polymerase chain reaction (RT-PCR) to assay the mRNA expression for Foxp3. RESULTS: (1) compared with groups A and B, the airway inflammation score of groups C, D and E increased significantly (all P < 0.01). Compared with group C, the airway inflammation score of groups D and E both increased (all P < 0.01), especially group D; (2) compared with groups A and B, the levels of IFN-γ, TNF-α and IL-8 in groups C, D and E increased (all P < 0.01) while those of IL-4 decreased. The levels of IFN-γ, TNF-α and IL-8 showed no difference between groups C and E. The levels of IFN-γ, TNF-α and IL-8 were higher in group D than those in groups C and E; (3) the ratio of Foxp3 + Treg cells in BALF was higher in group C (7.4% ± 0.8%), group D (7.8% ± 1.7%) and group E (7.0% ± 1.4%) than group A (4.8% ± 1.2%) and group B (4.7% ± 1.2%) (all P < 0.01). There were no differences in the ratio of Foxp3 + Treg cells among groups C, D and E (all P < 0.05); (4) there was an elevated expression of Foxp3 mRNA in group C (0.22 ± 0.02), group D (0.23 ± 0.03), group E (0.20 ± 0.04) versus group A (0.13 ± 0.01) and group B (0.11 ± 0.02) (all P < 0.01). But there was no difference in the expression of Foxp3 mRNA among groups C, D and E (all P > 0.05). CONCLUSIONS: airway inflammation induced by Th1/Tc1 and an elevated expression of Treg cells in BALF are found in smoke exposure rats. Upon smoking cessation, the above-mentioned airway inflammation still persists and the expression of Treg cells in BALF shows no decrease. It suggests that an immune imbalance may be involved in the progression of Th1/Tc1-induced airway inflammation upon smoking cessation.

[CD4(+)Foxp3(+) regulatory T cells in inflammation and emphysema after smoking cessation in rats].

OBJECTIVE: To evaluate the expression of Treg in a cigarette smoke-induced rat model of emphysema and after smoking cessation in the rats. METHODS: Fifty male Wistar rats were randomly divided into control group 1 (12 weeks), control group 2 (24 weeks), smoke-exposure group 1 (12 weeks), smoke-exposure group 2 (24 weeks) and smoking cessation group, with 10 rats in each group. Alveolar airspace enlargement was observed by hematoxylin-eosin (HE) staining. IL-8 and TNF-α levels in bronchoalveolar lavage fluid (BALF) were tested by ELISA. The proportion of CD4(+)Foxp3(+) Treg in peripheral blood and lungs of rats was determined by flow cytometry. The mRNA expression of Foxp3 was measured by real-time PCR. Comparisons of the data between different groups were performed using one-way ANOVA, and SNK and Games-Howell test was used for comparison between 2 groups. RESULTS: The mean linear intercept (MLI) in smoke-exposure group 1 and group 2 [(64.9 ± 5.3) µm, (77.9 ± 11.5) µm] was higher than those in the control group 1 and group 2 [(39.0 ± 3.8) µm, (40.3 ± 2.7) µm], all P < 0.01. Compared with smoke-exposure group 2, the MLI in smoking cessation group (71.5 ± 5.8) µm showed a lower value (P < 0.01), but still higher than that in smoke-exposure group 1 (P < 0.01). The IL-8 and TNF-α levels in BALF of smoke-exposure group 1 and group 2 [(68 ± 17) ng/L, (85 ± 16) ng/L], [(14.1 ± 1.8) ng/L, (20.1 ± 8.7) ng/L] were higher than those in control group 1 and group 2 [(44 ± 8) ng/L, (43 ± 9) ng/L], [(6.3 ± 2.3) ng/L, (5.8 ± 1.6) ng/L], all P < 0.05. The IL-8 and TNF-α levels were not statistically different between in smoking cessation group (56 ± 6) ng/L, (14.7 ± 4.7) ng/L and smoke-exposure group 1. The percentage of Treg in the lungs of smoke-exposure group 1 and group 2 [(6.6 ± 0.8)%, (5.3 ± 0.9)%] was significantly decreased as compared to control group 1 and group 2 [(9.0 ± 1.0)%, (9.6 ± 0.9)%], all P < 0.01. The percentage of Treg in lungs was not statistically different between smoke-exposure group 1 and smoking cessation group (7.2 ± 0.6)%. In peripheral blood, there was no significant difference between groups in the percentage of Treg. In the lung, Foxp3 mRNA expression in smoke-exposure group 1 and group 2 [(17 ± 7), (9 ± 7)] was less than that in control group 1 and group 2 [(39 ± 6), (42 ± 7)], all P < 0.01. The Foxp3 mRNA expression was not statistically different between smoke-exposure group 1 and smoking cessation group (21 ± 9). No significant differences in peripheral blood Foxp3 mRNA expression was found between groups. CONCLUSIONS: Decreased Treg was present in lungs of cigarette smoke-induced model of emphysema despite 12 weeks' smoking cessation, suggesting that down-regulation of Treg may be involved in the amplified and persistent inflammation after smoking cessation.