A small volume technique to examine and compare alveolar macrophage phagocytosis of apoptotic cells and non typeable Haemophilus influenzae (NTHi)

E-Cigarette Vapour Increases ACE2 and TMPRSS2 Expression in a Flavour- and Nicotine-Dependent Manner

COVID-19 infects via the respiratory system, but it can affect multiple systems and lead to multi system failure. There is growing evidence that smoking may be associated with higher rates of COVID-19 infections and worse outcomes due to increased levels of ACE2 in lung epithelial cells, but it is unknown whether E-cigarette use may lead to increased risk of COVID-19 infection from the SARS-CoV-2 virus. In this study, healthy donor bronchial epithelial cells (NHBE) and monocyte-derived macrophages (MDM) were exposed to cigarette smoke extract (CSE) or nicotine or flavoured E-cigarette vapour extract (EVE) before the assessment of SARS-CoV-2 recognition receptors ACE2 and TMPRSS2 genes. MDMs exposed to CSE and Tobacco EVE showed increased ACE2 expression; however, no treatment altered the TMPRSS2 expression. ACE2 was found to be upregulated by >2-fold in NHBE cells exposed to CSE, as well as nicotine, banana, or chocolate EVE, while TMPRSS2 was only upregulated by CSE or nicotine EVE exposure. These findings suggesting that flavourings can increase ACE2 expression in multiple cell types, while TMPRSS2 expression increases are limited to the epithelial cells in airways and may be limited to nicotine and/or cigarette smoke exposure. Therefore, increased risk of COVID-19 infection cannot be ruled out for vapers.

Molecular Mechanisms of Lipid Metabolism Disorders in Infectious Exacerbations of Chronic Obstructive Pulmonary Disease

Exacerbations largely determine the character of the progression and prognosis of chronic obstructive pulmonary disease (COPD). Exacerbations are connected with changes in the microbiological landscape in the bronchi due to a violation of their immune homeostasis. Many metabolic and immune processes involved in COPD progression are associated with bacterial colonization of the bronchi. The objective of this review is the analysis of the molecular mechanisms of lipid metabolism and immune response disorders in the lungs in COPD exacerbations. The complex role of lipid metabolism disorders in the pathogenesis of some infections is only beginning to be understood, however, there are already fewer and fewer doubts even now about its significance both in the pathogenesis of infectious exacerbations of COPD and in general in the progression of the disease. It is shown that the lipid rafts of the plasma membranes of cells are involved in many processes related to the detection of pathogens, signal transduction, the penetration of pathogens into the cell. Smoking disrupts the normally proceeded processes of lipid metabolism in the lungs, which is a part of the COPD pathogenesis.

AIM2 nuclear exit and inflammasome activation in chronic obstructive pulmonary disease and response to cigarette smoke

Introduction

The role inflammasomes play in chronic obstructive pulmonary disease (COPD) is unclear. We hypothesised that the AIM2 inflammasome is activated in the airways of COPD patients, and in response to cigarette smoke.

Methods

Lung tissue, bronchoscopy-derived alveolar macrophages and bronchial epithelial cells from COPD patients and healthy donors; lungs from cigarette smoke-exposed mice; and cigarette smoke extract-stimulated alveolar macrophages from healthy controls and HBEC30KT cell line were investigated. AIM2 inflammasome activation was assessed by multi-fluorescence quantitative confocal microscopy of speck foci positive for AIM2, inflammasome component ASC and cleaved IL-1β. Subcellular AIM2 localization was assessed by confocal microscopy, and immunoblot of fractionated cell lysates. Nuclear localization was supported by in-silico analysis of nuclear localization predicted scores of peptide sequences. Nuclear and cytoplasmic AIM2 was demonstrated by immunoblot in both cellular fractions from HBEC30KT cells.

Results

Increased cytoplasmic AIM2 speck foci, colocalized with cleaved IL-1β, were demonstrated in COPD lungs (n = 9) vs. control (n = 5), showing significant positive correlations with GOLD stages. AIM2 nuclear-to-cytoplasmic redistribution was demonstrated in bronchiolar epithelium in cigarette-exposed mice and in HBEC30KT cells post 24 h stimulation with 5% cigarette smoke extract. Alveolar macrophages from 8 healthy non-smokers responded to cigarette smoke extract with an > 8-fold increase (p < 0.05) of cytoplasmic AIM2 and > 6-fold increase (p < 0.01) of colocalized cleaved IL-1β speck foci, which were also localized with ASC.

Conclusion

The AIM2 inflammasome is activated in the airway of COPD patients, and in response to cigarette smoke exposure, associated with a nuclear to cytoplasmic shift in the distribution of AIM2.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12950-021-00286-4.

The role of oxidised self-lipids and alveolar macrophage CD1b expression in COPD

In chronic obstructive pulmonary disease (COPD) apoptotic bronchial epithelial cells are increased, and their phagocytosis by alveolar macrophages (AM) is decreased alongside bacterial phagocytosis. Epithelial cellular lipids, including those exposed on uncleared apoptotic bodies, can become oxidized, and may be recognized and presented as non-self by antigen presenting cells. CD1b is a lipid-presenting protein, previously only described in dendritic cells. We investigated whether CD1b is upregulated in COPD AM, and whether lipid oxidation products are found in the airways of cigarette smoke (CS) exposed mice. We also characterise CD1b for the first time in a range of macrophages and assess CD1b expression and phagocytic function in response to oxidised lipid. Bronchoalveolar lavage and exhaled breath condensate were collected from never-smoker, current-smoker, and COPD patients and AM CD1b expression and airway 8-isoprostane levels assessed. Malondialdehyde was measured in CS-exposed mouse airways by confocal/immunofluorescence. Oxidation of lipids produced from CS-exposed 16HBE14o- (HBE) bronchial epithelial cells was assessed by spectrophotometry and changes in lipid classes assessed by mass spectrometry. 16HBE cell toxicity was measured by flow cytometry as was phagocytosis, CD1b expression, HLA class I/II, and mannose receptor (MR) in monocyte derived macrophages (MDM). AM CD1b was significantly increased in COPD smokers (4.5 fold), COPD ex-smokers (4.3 fold), and smokers (3.9 fold), and AM CD1b significantly correlated with disease severity (FEV₁) and smoking pack years. Airway 8-isoprostane also increased in smokers and COPD smokers and ex-smokers. Malondialdehyde was significantly increased in the bronchial epithelium of CS-exposed mice (MFI of 18.18 vs 23.50 for control). Oxidised lipid was produced from CS-exposed bronchial epithelial cells (9.8-fold of control) and showed a different overall lipid makeup to that of control total cellular lipid. This oxidised epithelial lipid significantly upregulated MDM CD1b, caused bronchial epithelial cell toxicity, and reduced MDM phagocytic capacity and MR in a dose dependent manner. Increased levels of oxidised lipids in the airways of COPD patients may be responsible for reduced phagocytosis and may become a self-antigen to be presented by CD1b on macrophages to perpetuate disease progression despite smoking cessation.

E-cigarettes and health risks: more to the flavor than just the name

The growing interest in regulating flavored E-liquids must incorporate understanding of the "flavoring profile" of each E-liquid-which flavorings (flavoring chemicals) are present and at what concentrations not just focusing on the flavor on the label. We investigated the flavoring profile of 10 different flavored E-liquids. We assessed bronchial epithelial cell viability and apoptosis, phagocytosis of bacteria and apoptotic cells by macrophages after exposure to E-cigarette vapor extract (EVE). We validated our data in normal human bronchial epithelial cells (NHBE) and alveolar macrophages (AM) from healthy donors. We also assessed cytokine release and validated in the saliva from E-cigarette users. Increased necrosis/apoptosis (16.1-64.5% apoptosis) in 16HBE cells was flavor dependent, and NHBEs showed an increased susceptibility to flavors. In THP-1 differentiated macrophages phagocytosis was also flavor dependent, with AM also showing increased susceptibility to flavors. Further, Banana and Chocolate were shown to reduce surface expression of phagocytic target recognition receptors on alveolar macrophages. Banana and Chocolate increased IL-8 secretion by NHBE, whereas all 4 flavors reduced AM IL-1β secretion, which was also reduced in the saliva of E-cigarette users compared with healthy controls. Flavorant profiles of E-liquids varied from simple 2 compound mixtures to complex mixtures containing over a dozen flavorants. E-liquids with high benzene content, complex flavoring profiles, high chemical concentration had the greatest impacts. The Flavorant profile of E-liquids is key to disruption of the airway status quo by increasing bronchial epithelial cell apoptosis, causing alveolar macrophage phagocytic dysfunction, and altering airway cytokines.

Sphingosine signaling dysfunction in airway cells as a potential contributor to progression from protracted bacterial bronchitis to bronchiectasis in children

AIM

Protracted bacterial bronchitis (PBB) is considered a potential precursor to bronchiectasis (BE) in some children. We previously showed that alveolar macrophages (AM) from children with PBB or BE have a similar significant defect in phagocytic capacity, with proinflammatory associations. We hypothesized that the mechanisms responsible for this defect involve dysregulation of the sphingosine-1-phosphate (S1P) signaling pathway, as we have found in adult inflammatory lung diseases.

METHOD

We employed a Custom TaqMan OpenArray to investigate gene expression of S1P-generating enzymes: sphingosine kinases (SPHK) 1/2, S1P phosphatase 2 (SGPP2), S1P lyase 1 (SGPL1), S1P receptors (S1PR) 1/2/4/5; proinflammatory cytokines TNF-α (TNF) and IFNγ (IFNG), the cytotoxic mediator granzyme B (GZMB), and inflammasomes AIM2 and NLRP3, in bronchoalveolar lavage from 15 children with BE, 15 with PBB and 17 age-matched controls, and determined association with clinical/demographic variables and airway inflammation.

RESULT

Significantly increased expression of S1PR1, S1PR2, and SPHK1 was noted in PBB and BE AM vs controls with increased SGPP2 only in PBB. TNF, IFNG, AIM2, and NLRP3 were significantly increased in both disease groups with increased GZMB only in PBB. There were no significant differences in the expression of any other S1P-related mediator between groups. There were significant positive associations between Haemophilus influenzae growth and expression of S1PR1 and NLRP3; between S1PR1 and S1PR2, NLRP3 and IFNG; between S1PR2 and AIM2, SPHK1, and SPHK2; and between SPHK1 and GZMB, IFNG, AIM2, and NLRP3.

CONCLUSION

Children with PBB and BE share similar S1P-associated gene expression profiles. AM phagocytic dysfunction and inflammation in these children may occur due to dysregulated S1P signaling.

Long-Term Azithromycin Reduces Haemophilus influenzae and Increases Antibiotic Resistance in Severe Asthma

Rationale: The macrolide antibiotic azithromycin reduces exacerbations in adults with persistent symptomatic asthma. However, owing to the pleotropic properties of macrolides, unintended bacteriological consequences such as augmented pathogen colonization or dissemination of antibiotic-resistant organisms can occur, calling into question the long-term safety of azithromycin maintenance therapy.Objectives: To assess the effects of azithromycin on the airway microbiota, pathogen abundance, and carriage of antibiotic resistance genes.Methods: 16S rRNA sequencing and quantitative PCR were performed to assess the effect of azithromycin on sputum microbiology from participants of the AMAZES (Asthma and Macrolides: The Azithromycin Efficacy and Safety) trial: a 48-week, double-blind, placebo-controlled trial of thrice-weekly 500 mg oral azithromycin in adults with persistent uncontrolled asthma. Pooled-template shotgun metagenomic sequencing, quantitative PCR, and isolate whole-genome sequencing were performed to assess antibiotic resistance.Measurements and Main Results: Paired sputum samples were available from 61 patients (n = 34 placebo, n = 27 azithromycin). Azithromycin did not affect bacterial load (P = 0.37) but did significantly decrease Faith's phylogenetic diversity (P = 0.026) and Haemophilus influenzae load (P < 0.0001). Azithromycin did not significantly affect levels of Streptococcus pneumoniae, Staphylococcus aureus, Pseudomonas aeruginosa, or Moraxella catarrhalis. Of the 89 antibiotic resistance genes detected, five macrolide resistance genes and two tetracycline resistance genes were increased significantly.Conclusions: In patients with persistent uncontrolled asthma, azithromycin reduced airway H. influenzae load compared with placebo but did not change total bacterial load. Macrolide resistance increased, reflecting previous studies. These results highlight the need for studies assessing the efficacy of nonantibiotic macrolides as a long-term therapy for patients with persistent uncontrolled asthma.

Prospective community programme versus parent-driven care to prevent respiratory morbidity in children following hospitalisation with severe bronchiolitis or pneumonia

Background

Hospitalisation with severe lower respiratory tract infection (LRTI) in early childhood is associated with ongoing respiratory symptoms and possible later development of bronchiectasis. We aimed to reduce this intermediate respiratory morbidity with a community intervention programme at time of discharge.

Methods

This randomised, controlled, single-blind trial enrolled children aged <2 years hospitalised for severe LRTI to ‘intervention’ or ‘control’. Intervention was three monthly community clinics treating wet cough with prolonged antibiotics referring non-responders. All other health issues were addressed, and health resilience behaviours were encouraged, with referrals for housing or smoking concerns. Controls followed the usual pathway of parent-initiated healthcare access. After 24 months, all children were assessed by a paediatrician blinded to randomisation for primary outcomes of wet cough, abnormal examination (crackles or clubbing) or chest X-ray Brasfield score ≤22.

Findings

400 children (203 intervention, 197 control) were enrolled in 2011–2012; mean age 6.9 months, 230 boys, 87% Maori/Pasifika ethnicity and 83% from the most deprived quintile. Final assessment of 321/400 (80.3%) showed no differences in presence of wet cough (33.9% intervention, 36.5% controls, relative risk (RR) 0.93, 95% CI 0.69 to 1.25), abnormal examination (21.7% intervention, 23.9% controls, RR 0.92, 95% CI 0.61 to 1.38) or Brasfield score ≤22 (32.4% intervention, 37.9% control, RR 0.85, 95% CI 0.63 to 1.17). Twelve (all intervention) were diagnosed with bronchiectasis within this timeframe.

Interpretation

We have identified children at high risk of ongoing respiratory disease following hospital admission with severe LRTI in whom this intervention programme did not change outcomes over 2 years.

Trial registration number

ACTRN12610001095055.

Bushfire smoke is pro-inflammatory and suppresses macrophage phagocytic function

Bushfires are increasing in frequency and severity worldwide. Bushfire smoke contains organic/inorganic compounds including aldehydes and acrolein. We described suppressive effects of tobacco smoke on the phagocytic capacity of airway macrophages, linked to secondary necrosis of uncleared apoptotic epithelial cells, persistence of non-typeable H. influenzae (NTHi), and inflammation. We hypothesised that bushfire smoke extract (BFSE) would similarly impair macrophage function. THP-1 or monocyte-derived macrophages (MDM) were exposed to 1-10% BFSE prepared from foliage of 5 common Australian native plants (genus Acacia or Eucalyptus), or 10% cigarette smoke extract (CSE). Phagocytic recognition receptors were measured by flow cytometry; pro-inflammatory cytokines and caspase 1 by immunofluorescence or cytometric bead array; viability by LDH assay; and capsase-3/PARP by western blot. BFSE significantly decreased phagocytosis of apoptotic cells or NTHi by both THP-1 macrophages and MDM vs air control, consistent with the effects of CSE. BFSE significantly decreased MDM expression of CD36, CD44, SR-A1, CD206 and TLR-2 and increased active IL-1β, caspase-1 and secreted IL-8. BFSE dose-dependently decreased THP-1 macrophage viability (5-fold increase in LDH at 10%) and significantly increased active caspase-3. BFSE impairs macrophage function to a similar extent as CSE, highlighting the need for further research, especially in patients with pre-existing lung disease.

Phagocytosis and Inflammation: Exploring the effects of the components of E-cigarette vapor on macrophages

E‐cigarettes are perceived as harmless; however, evidence of their safety is lacking. New data suggests E‐cigarettes discharge a range of compounds capable of physiological damage to users. We previously established that cigarette smoke caused defective alveolar macrophage phagocytosis. The present study compared the effect E‐cigarette of components; E‐liquid flavors, nicotine, vegetable glycerine, and propylene glycol on phagocytosis, proinflammatory cytokine secretion, and phagocytic recognition molecule expression using differentiated THP‐1 macrophages. Similar to CSE, phagocytosis of NTHi bacteria was significantly decreased by E‐liquid flavoring (11.65–15.75%) versus control (27.01%). Nicotine also decreased phagocytosis (15.26%). E‐liquid, nicotine, and E‐liquid+ nicotine reduced phagocytic recognition molecules; SR‐A1 and TLR‐2. IL‐8 secretion increased with flavor and nicotine, while TNFα, IL‐1β, IL‐6, MIP‐1α, MIP‐1β, and MCP‐1 decreased after exposure to most flavors and nicotine. PG, VG, or PG:VG mix also induced a decrease in MIP‐1α and MIP‐1β. We conclude that E‐cigarettes can cause macrophage phagocytic dysfunction, expression of phagocytic recognition receptors and cytokine secretion pathways. As such, E‐cigarettes should be treated with caution by users, especially those who are nonsmokers.

Lung Macrophage Phenotypes and Functional Responses: Role in the Pathogenesis of COPD

Lung macrophages (LMs) are essential immune effector cells that are pivotal in both innate and adaptive immune responses to inhaled foreign matter. They either reside within the airways and lung tissues (from early life) or are derived from blood monocytes. Similar to macrophages in other organs and tissues, LMs have natural plasticity and can change phenotype and function depending largely on the microenvironment they reside in. Phenotype changes in lung tissue macrophages have been implicated in chronic inflammatory responses and disease progression of various chronic lung diseases, including Chronic Obstructive Pulmonary Disease (COPD). LMs have a wide variety of functional properties that include phagocytosis (inorganic particulate matter and organic particles, such as viruses/bacteria/fungi), the processing of phagocytosed material, and the production of signaling mediators. Functioning as janitors of the airways, they also play a key role in removing dead and dying cells, as well as cell debris (efferocytic functions). We herein review changes in LM phenotypes during chronic lung disease, focusing on COPD, as well as changes in their functional properties as a result of such shifts. Targeting molecular pathways involved in LM phenotypic shifts could potentially allow for future targeted therapeutic interventions in several diseases, such as COPD.

Disrupted epithelial/macrophage crosstalk via Spinster homologue 2-mediated S1P signaling may drive defective macrophage phagocytic function in COPD

Introduction

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.

Methods

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.

Results

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.

Conclusion

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.

Nonantibiotic macrolides restore airway macrophage phagocytic function with potential anti-inflammatory effects in chronic lung diseases

We reported defective efferocytosis associated with cigarette smoking and/or airway inflammation in chronic lung diseases, including chronic obstructive pulmonary disease, severe asthma, and childhood bronchiectasis. We also showed defects in phagocytosis of nontypeable Haemophilus influenzae (NTHi), a common colonizer of the lower airway in these diseases. These defects could be substantially overcome with low-dose azithromycin; however, chronic use may induce bacterial resistance. The aim of the present study was therefore to investigate two novel macrolides-2'-desoxy-9-(S)-erythromycylamine (GS-459755) and azithromycin-based 2'-desoxy molecule (GS-560660)-with significantly diminished antibiotic activity against Staphylococcus aureus, Streptococcus pneumonia, Moraxella catarrhalis, and H. influenzae We tested their effects on efferocytosis, phagocytosis of NTHi, cell viability, receptors involved in recognition of apoptotic cells and/or NTHi (flow cytometry), secreted and cleaved intracellular IL-1β (cytometric bead array, immunofluorescence/confocal microscopy), and nucleotide-binding oligomerization domain-like receptor family pyrin domain-containing 3 (NLRP3) using primary alveolar macrophages and THP-1 macrophages ± 10% cigarette smoke extract. Dose-response experiments showed optimal prophagocytic effects of GS-459755 and GS-560660 at concentrations of 0.5-1 µg/ml compared with our findings with azithromycin. Both macrolides significantly improved phagocytosis of apoptotic cells and NTHi (e.g., increases in efferocytosis and phagocytosis of NTHi: GS-459755, 23 and 22.5%, P = 0.043; GS-560660, 23.5 and 22%, P = 0.043, respectively). Macrophage viability remained >85% following 24 h exposure to either macrolide at concentrations up to 20 µg/ml. Secreted and intracellular-cleaved IL-1β was decreased with both macrolides with no significant changes in recognition molecules c-mer proto-oncogene tyrosine kinase; scavenger receptor class A, member 1; Toll-like receptor 2/4; or CD36. Particulate cytoplasmic immunofluorescence of NLRP3 inflammasome was also reduced significantly. We conclude that GS-459755 and GS-560660 may be useful for reducing airway inflammation in chronic lung diseases without inducing bacterial resistance.

Immunization with Protein D from Non-Typeable Haemophilus influenzae (NTHi) Induced Cytokine Responses and Bioactive Antibody Production

Background

Outer membrane protein D (PD) is a highly conserved and stable protein in the outer membrane of both encapsulated (typeable) and non-capsulated (non-typeable) strains of Haemophilus influenzae. As an immunogen, PD is a potential candidate vaccine against non-typeable H. influenzae (NTHi) strains.

Objectives

The aim of this study was to determine the cytokine pattern and the opsonic antibody response in a BALB/c mouse model versus PD from NTHi as a vaccine candidate.

Methods

Protein D was formulated with Freund’s and outer membrane vesicle (OMV) adjuvants and injected into experimental mice. Sera from all groups were collected. The bioactivity of the anti-PD antibody was determined by opsonophagocytic killing test. To evaluate the cytokine responses, the spleens were assembled, suspension of splenocytes was recalled with antigen, and culture supernatants were analyzed by ELISA for IL-4, IL-10, and IFN-γ cytokines.

Results

Anti-PD antibodies promoted phagocytosis of NTHi in both immunized mice groups (those administered PD + Freund’s and those administered PD + OMV adjuvants, 92.8% and 83.5%, respectively, compared to the control group). In addition, the concentrations of three cytokines were increased markedly in immunized mice.

Conclusions

We conclude that immunization with PD protects mice against NTHi. It is associated with improvements in both cellular and humoral immune responses and opsonic antibody activity.