We have previously shown that the defective ability of alveolar macrophages (AM) to phagocytose apoptotic cells ('efferocytosis') in chronic obstructive pulmonary disease/emphysema (COPD) could be ...therapeutically improved using the C-type lectin, mannose binding lectin (MBL), although the exact mechanisms underlying this effect are unknown. An S-type lectin, galectin-3, is also known to regulate macrophage phenotype and function, via interaction with its receptor CD98. We hypothesized that defective expression of galectin/CD98 would be associated with defective efferocytosis in COPD and that mechanisms would include effects on cytoskeletal remodeling and macrophage phenotype and glutathione (GSH) availability. Galectin-3 was measured by ELISA in BAL from controls, smokers and current/ex-smokers with COPD. CD98 was measured on AM using flow cytometry. We assessed the effects of galectin-3 on efferocytosis, CD98, GSH, actin polymerisation, rac activation, and the involvement of PI3K (using β-actin probing and wortmannin inhibition) in vitro using human AM and/or MH-S macrophage cell line. Significant decreases in BAL galectin-3 and AM CD98 were observed in BAL from both current- and ex-smoker COPD subjects vs controls. Galectin 3 increased efferocytosis via an increase in active GTP bound Rac1. This was confirmed with β-actin probing and the role of PI3K was confirmed using wortmannin inhibition. The increased efferocytosis was associated with increases in available glutathione and expression of CD98. We provide evidence for a role of airway lectins in the failed efferocytosis in COPD, supporting their further investigation as potential macrophage-targeted therapies.
We have previously established a link between impaired phagocytic capacity and deregulated S1P signaling in alveolar macrophages from COPD subjects. We hypothesize that this defect may include a ...disruption of epithelial-macrophage crosstalk via Spns2-mediated intercellular S1P signaling.
Primary alveolar macrophages and bronchial epithelial cells from COPD subjects and controls, cell lines, and a mouse model of chronic cigarette smoke exposure were studied. Cells were exposed to 10% cigarette smoke extract, or vehicle control. Spns2 expression and subcellular localization was studied by immunofluorescence, confocal microscopy and RT-PCR. Phagocytosis was assessed by flow-cytometry. Levels of intra- and extracellular S1P were measured by S1P 3H-labeling.
Spns2 expression was significantly increased (p<0.05) in alveolar macrophages from current-smokers/COPD patients (n = 5) compared to healthy nonsmokers (n = 8) and non-smoker lung transplant patients (n = 4). Consistent with this finding, cigarette smoke induced a significant increase in Spns2 expression in both human alveolar and THP-1 macrophages. In contrast, a remarkable Spns2 down-regulation was noted in response to cigarette smoke in 16HBE14o- cell line (p<0.001 in 3 experiments), primary nasal epithelial cells (p<0.01 in 2 experiments), and in smoke-exposed mice (p<0.001, n = 6 animals per group). Spns2 was localized to cilia in primary bronchial epithelial cells. In both macrophage and epithelial cell types, Spns2 was also found localized to cytoplasm and the nucleus, in line with a predicted bipartile Nuclear Localization Signal at the position aa282 of the human Spns2 sequence. In smoke-exposed mice, alveolar macrophage phagocytic function positively correlated with Spns2 protein expression in bronchial epithelial cells.
Our data suggest that the epithelium may be the major source for extracellular S1P in the airway and that there is a possible disruption of epithelial/macrophage cross talk via Spns2-mediated S1P signaling in COPD and in response to cigarette smoke exposure.
Defective efferocytosis (phagocytic clearance of apoptotic cells) in the airway may perpetuate inflammation via secondary necrosis in chronic obstructive pulmonary disease (COPD). We have previously ...reported that low-dose azithromycin improved alveolar macrophage (AM) phagocytic function in vitro.
We investigated collectins (mannose-binding lectin MBL and surfactant protein SP-D) and mannose receptor (MR) in COPD and their possible role in the azithromycin-mediated improvement in phagocytosis.
In vitro effects of azithromycin on AM expression of MR were investigated. MBL, SP-D, and MR were measured in patients with COPD and control subjects. Azithromycin (250 mg orally daily for 5 d then twice weekly for 12 wk) was administered to 11 patients with COPD. Assessments included AM phagocytic ability and expression of MR, MBL, SP-D, bronchial epithelial cell apoptosis, pulmonary function, C-reactive protein, blood/BAL leukocyte counts, cytokine production, and T-cell markers of activation and phenotype.
Azithomycin (500 ng/ml) increased MR expression by 50% in vitro. AM MR expression and levels of MBL and SP-D were significantly reduced in patients with COPD compared with control subjects. In patients with COPD, after azithromycin therapy, we observed significantly improved AM phagocytic ability (pre: 9.9%; post: 15.1%), reduced bronchial epithelial cell apoptosis (pre: 30.0%; post: 19.7%), and increased MR and reduced inflammatory markers in the peripheral blood. These findings implicate the MR in the defective phagocytic function of AMs in COPD and as a target for the azithromycin-mediated improvement in phagocytic ability.
Our findings indicate a novel approach to supplement existing therapies in COPD.
ABSTRACT
Pulmonary complications in CTD are common and can involve the interstitium, airways, pleura and pulmonary vasculature. ILD can occur in all CTD (CTD‐ILD), and may vary from limited, ...non‐progressive lung involvement, to fulminant, life‐threatening disease. Given the potential for major adverse outcomes in CTD‐ILD, accurate diagnosis, assessment and careful consideration of therapeutic intervention are a priority. Limited data are available to guide management decisions in CTD‐ILD. Autoimmune‐mediated pulmonary inflammation is considered a key pathobiological pathway in these disorders, and immunosuppressive therapy is generally regarded the cornerstone of treatment for severe and/or progressive CTD‐ILD. However, the natural history of CTD‐ILD in individual patients can be difficult to predict, and deciding who to treat, when and with what agent can be challenging. Establishing realistic therapeutic goals from both the patient and clinician perspective requires considerable expertise. The document aims to provide a framework for clinicians to aid in the assessment and management of ILD in the major CTD. A suggested approach to diagnosis and monitoring of CTD‐ILD and, where available, evidence‐based, disease‐specific approaches to treatment have been provided.
Chronic obstructive pulmonary disease (COPD) is associated with defective efferocytosis (apoptosis and alveolar macrophage AM phagocytic function) that may lead to secondary necrosis and tissue ...damage. We investigated ex vivo AM phagocytic ability and recognition molecules (CD36, integrin alphaVbeta3, CD31, CD91, CD44) using flow cytometry. The transferrin receptor (CD71) was measured as an indicator of monocyte-macrophage differentiation in bronchoalveolar lavage (BAL). Proliferation was assessed with Ki-67. Based on evidence of systemic involvement in COPD, blood from 17 current smokers and 25 ex-smokers with COPD, 22 healthy smokers, and 20 never-smoking control subjects was also investigated. BAL was collected from 10 to 16 subjects in each group. Levels of recognition molecules and cAMP were assessed after exposure of AM to cigarette smoke in vitro. The phagocytic ability of AM was significantly decreased in both COPD groups and in healthy smokers compared with control subjects. However, phagocytic capacity was better in subjects with COPD who had ceased smoking, compared with those who were still smoking. AM from current smokers with COPD and healthy smokers exhibited reduced CD31, CD91, CD44, and CD71, and enhanced Ki-67 compared with healthy never-smoker control subjects. There were no differences in these markers in AM from ex-smokers with COPD compared with control subjects, or in blood monocytes from any group. Suppressive effects of cigarette smoke on AM recognition molecules associated with an increase in cAMP were confirmed in vitro. Our data indicates that a smoking-related reduction in AM phagocytic ability and expression of several important recognition molecules may be at least partially normalized in those subjects with COPD who have ceased smoking.
Asthma is a chronic inflammatory disorder of the airways where bacteria may act as protagonists of chronic inflammation. Little is known about the relation of airway inflammation to the presence of ...specific bacterial taxa. We sought to describe the sputum microbiome in adults with poorly controlled asthma.DNA was extracted from induced sputum and microbial communities were profiled using 16S rRNA pyrosequencing. Bacterial species were characterised, and the relationship between microbial populations, asthma inflammatory subtypes and other covariates was explored. Real-time PCR was used to identify Tropheryma whipplei and Haemophilus influenzae in sputum.Adults with neutrophilic asthma had reduced bacterial diversity and species richness. Tropheryma was identified and confirmed with real-time PCR in 12 (40%) participants. Haemophilus occurred most often in a group of younger atopic males with an increased proportion of neutrophils. PCR confirmed the presence of H. influenzae in 35 (76%) participants with poorly controlled asthma.There are phenotype-specific alterations to the airway microbiome in asthma. Reduced bacterial diversity combined with a high prevalence of H. influenzae was observed in neutrophilic asthma, whereas eosinophilic asthma had abundant T. whipplei.
ABSTRACT
Background and objective
E‐cigarettes are often marketed and thought of as emitting harmless vapour; however, verification of their safety for non‐smokers is scarce. We have previously shown ...that E‐cigarettes cause decreased phagocytosis of bacteria by macrophages via reductions in surface bacterial recognition receptors. This study assessed the effect of E‐cigarette constituents, 3 E‐liquid apple flavours, nicotine, vegetable glycerine and propylene glycol, on bronchial epithelial cell viability, apoptosis and cytokine secretion and macrophage phagocytosis of apoptotic airway cells and phagocytic recognition molecules.
Methods
Cell necrosis and apoptosis were measured by Sytox Green stain and Annexin V. Efferocytosis was measured by internalization of pHrodo Green labelled apoptotic airway cells by macrophages. Expression of macrophage cell surface apoptotic cell receptors was measured by flow cytometry. Cytokine release by E‐cigarette‐exposed airway cells was measured by cytokine bead array.
Results
E‐cigarette vapour increased primary bronchial epithelial necrosis and apoptosis. E‐cigarette vapour reduced efferocytosis (lowest flavour 12.1%) versus control (20.2%, P = 0.032). The efferocytosis receptor CD44 was reduced by one flavour (MFI 1863 vs 2332 control, P = 0.016) and all components reduced expression of CD36, including the glycol bases (MFI 1067–12 274 vs 1415 control). Reduced secretion of TNF‐α, IL‐6, IP‐10, MIP‐1α and MIP‐1β was observed for all flavour variants.
Conclusion
E‐cigarettes can cause bronchial epithelial apoptosis and macrophage efferocytosis dysfunction via reduced expression of apoptotic cell recognition receptors. These data further show that E‐cigarettes should not be considered harmless to non‐smokers and their effects may go far beyond cytotoxicity to cells.
E‐cigarettes are increasing in popularity, especially amongst non‐smokers. We assess not only the toxicity of E‐cigarettes on healthy airway epithelial cells and effect on secreted cytokines, but also, for the first time, the effect on efferocytosis of apoptotic airway cells by macrophages.
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Background Asthma is a heterogeneous chronic inflammatory disease in which host defense against respiratory viruses such as human rhinovirus (HRV) may be abnormal. This is a matter of some ...controversy, with some investigators reporting reduced type I interferon (IFN) synthesis and others suggesting that type I IFN synthesis is relatively normal in asthma. Objective The objective of this study was to examine the responsiveness of circulating mononuclear cells to HRV in a large cohort of participants with poorly controlled asthma and determine whether IFN-α and IFN-β synthesis varies across different inflammatory phenotypes. Methods Eligible adults with asthma (n = 86) underwent clinical assessment, sputum induction, and blood sampling. Asthma inflammatory subtypes were defined by sputum cell count, and supernatant assessed for IL-1β. Peripheral blood mononuclear cells (PBMCs) were exposed to HRV serotype 1b, and IFN-α and IFN-β release was measured by enzyme-linked immunosorbent assay. Results Participants (mean age, 59 years; atopy, 76%) had suboptimal asthma control (mean asthma control questionnaire 6, 1.7). In those with neutrophilic asthma (n = 12), HRV1b-stimulated PBMCs produced significantly less IFN-α than PBMCs from participants with eosinophilic (n = 35) and paucigranulocytic asthma (n = 35). Sputum neutrophil proportion and the dose of inhaled corticosteroids were independent predictors of reduced IFN-α production after HRV1b exposure. Conclusions Antiviral type I IFN production is impaired in those with neutrophilic airway inflammation and in those prescribed high doses of inhaled corticosteroids. Our study is an important step toward identifying those with poorly controlled asthma who might respond best to inhaled IFN therapy during exacerbations.
Idiopathic pulmonary fibrosis (IPF) is a lung disease of unknown cause characterised by progressive scarring, with limited effective treatment and a median survival of only 2-3 years. Our aim was to ...identify potential occupational and environmental exposures associated with IPF in Australia.
Cases were recruited by the Australian IPF registry. Population-based controls were recruited by random digit dialling, frequency matched on age, sex and state. Participants completed a questionnaire on demographics, smoking, family history, environmental and occupational exposures. Occupational exposure assessment was undertaken with the Finnish Job Exposure Matrix and Australian asbestos JEM. Multivariable logistic regression was used to describe associations with IPF as ORs and 95% CIs, adjusted for age, sex, state and smoking.
We recruited 503 cases (mean±SD age 71±9 years, 69% male) and 902 controls (71±8 years, 69% male). Ever smoking tobacco was associated with increased risk of IPF: OR 2.20 (95% CI 1.74 to 2.79), but ever using marijuana with reduced risk after adjusting for tobacco: 0.51 (0.33 to 0.78). A family history of pulmonary fibrosis was associated with 12.6-fold (6.52 to 24.2) increased risk of IPF. Occupational exposures to secondhand smoke (OR 2.1; 1.2 to 3.7), respirable dust (OR 1.38; 1.04 to 1.82) and asbestos (OR 1.57; 1.15 to 2.15) were independently associated with increased risk of IPF. However occupational exposures to other specific organic, mineral or metal dusts were not associated with IPF.
The burden of IPF could be reduced by intensified tobacco control, occupational dust control measures and elimination of asbestos at work.
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