Systemic IL-26 correlates with improved asthma control in children sensitized to dog allergen

BACKGROUND

Interleukin (IL)-26 is produced by T helper type 17 (Type 17) cells and exerts immunomodulatory plus antimicrobial effects. Previous studies show that local IL-26 concentrations in the airways are higher in patients with uncontrolled than in those with controlled asthma, and that this intriguing cytokine bears biomarker potential. Here, we determined how systemic IL-26 relates to allergen sensitization, asthma severity, and to IL-17 A in children.

METHODS

Serum samples were obtained from children with (n = 60) and without (n = 17) sensitization to dog allergen, and IL-26 and IL-17 A protein concentrations were measured using ELISA. Self-reported history, including medication use and validated symptom-based questionnaire scores, was recorded.

RESULTS

The serum concentrations of IL-26 were enhanced in allergen-sensitized subjects and correlated with those of IL-17 A in a positive manner. However, the IL-26 concentrations did not markedly differ between allergen-sensitized subjects with and without asthma, eczema, allergic rhinitis, or a history of food allergy. Notably, IL-26 concentrations correlated with increasing Asthma Control Test (ACT) scores in a positive manner and with inhaled corticosteroid in a negative manner, amongst sensitized subjects with asthma. Moreover, subjects with asthma requiring ≥ 1 course of oral corticosteroids in the preceding 12 months had decreased IL-26 concentrations.

CONCLUSION

This study forwards evidence that systemic IL-26, just like IL-17 A, is involved in allergen sensitization among children. The association of systemic IL-26 with improved asthma control is compatible with the cellular sources being recruited into the airways in severe asthma, which supports that this kinocidin bears potential as a biomarker and therapeutic target.

Protein N-glycosylation in the bronchoalveolar space differs between never-smokers and long-term smokers with and without COPD

Chronic obstructive pulmonary disease (COPD) kills millions of people annually and patients suffering from exacerbations of this disorder display high morbidity and mortality. The clinical course of COPD is associated with dysbiosis and infections, but the underlying mechanisms are poorly understood. Glycosylation of proteins play roles in regulating interactions between microbes and immune cells, and knowledge on airway glycans therefore contribute to the understanding of infections. Furthermore, glycans have biomarker potential for identifying smokers with enhanced risk for developing COPD as well as COPD subgroups. Here, we characterized the N-glycosylation in the lower airways of healthy never-smokers (HNS, n = 5) and long-term smokers (LTS) with (LTS+, n = 4) and without COPD (LTS-, n = 8). Using mass spectrometry, we identified 57 highly confident N-glycan structures whereof 38 oligomannose, complex, and paucimannose type glycans were common to BAL samples from HNS, LTS- and LTS+ groups. Hybrid type N-glycans were identified only in the LTS+ group. Qualitatively and quantitatively, HNS had lower inter-individual variation between samples compared to LTS- or LTS+. Cluster analysis of BAL N-glycosylation distinguished LTS from HNS. Correlation analysis with clinical parameters revealed that complex N-glycans were associated with health and absence of smoking whereas oligomannose N-glycans were associated with smoking and disease. The N-glycan profile from monocyte-derived macrophages differed from the BAL N-glycan profiles. In conclusion, long-term smokers display substantial alterations of N-glycosylation in the bronchoalveolar space, and the hybrid N-glycans identified only in long-term smokers with COPD deserve to be further studied as potential biomarkers.

TLR4-mediated release of heparin-binding protein in human airways: a co-stimulatory role for IL-26

Background

Bacterial infection causes accumulation of neutrophils that release antimicrobial proteins including heparin-binding protein (HBP). In human airways, this neutrophil accumulation can be re-capitulated via intrabronchial exposure to lipopolysaccharide (LPS), a Toll-like receptor 4 (TLR4) agonist, that also causes a local increase in the neutrophil-mobilizing cytokine IL-26. Although LPS is considered a weak stimulus for HBP release ex vivo, its effect on HBP release in human airways in vivo has not been characterized.

Methods

We determined whether intrabronchial exposure to LPS causes concomitant release of HBP and IL-26 in human airways, and whether IL-26 can enhance LPS-induced release of HBP in isolated human neutrophils.

Results

We found that the concentration of HBP was markedly increased in bronchoalveolar lavage (BAL) fluid 12, 24, and 48 hours after LPS exposure, and that it displayed a strong and positive correlation with that of IL-26. Moreover, the concentration of HBP in conditioned media from isolated neutrophils was enhanced only after co-stimulation with LPS and IL-26.

Conclusions

Taken together, our findings indicate that TLR4 stimulation causes concomitant release of HBP and IL-26 in human airways, and that IL-26 may constitute a required co-stimulant for HBP release in neutrophils, thus enabling the concerted action of HBP and IL-26 in local host defense.

Comorbid conditions as predictors of mortality in severe COPD - an eight-year follow-up cohort study

Purpose

Co-morbidities are common in chronic obstructive pulmonary disease (COPD) and are associated with increased morbidity and mortality. The aim of the present study was to explore the prevalence of several comorbid conditions in severe COPD, and to investigate and compare their associations with long-term mortality.

Methods

In May 2011 to March 2012, 241 patients with COPD stage 3 or 4 were included in the study. Information was collected on sex, age, smoking history, weight and height, current pharmacological treatment, number of exacerbations the recent year and comorbid conditions. At December 31st, 2019, mortality data (all-cause and cause specific) were collected from the National Cause of Death Register. Data were analyzed using Cox-regression analysis with gender, age, previously established predictors of mortality and comorbid conditions as independent variables, and all-cause mortality and cardiac and respiratory mortality, respectively, as dependent variables.

Results

Out of 241 patients, 155 (64%) were deceased at the end of the study period; 103 patients (66%) died of respiratory disease and 25 (16%) of cardiovascular disease. Impaired kidney function was the only comorbid condition independently associated with increased all-cause mortality (HR (95% CI) 3.41 (1.47-7.93) p=0.004) and respiratory mortality (HR (95%CI) 4.63 (1.61 to 13.4), p = 0.005). In addition, age ≥70, BMI <22 and lower FEV1 expressed as %predicted were significantly associated with increased all-cause and respiratory mortality.

Conclusion

In addition to the risk factors high age, low BMI and poor lung function; impaired kidney function appears to be an important risk factor for mortality in the long term, which should be taken into account in the medical care of patients with severe COPD.

Causal analysis of plasma IL-8 on carotid intima media thickness, a measure of subclinical atherosclerosis

BACKGROUND

We investigated the causality of IL-8 on carotid intima-media thickness (c-IMT), a measure of sub-clinical atherosclerosis.

METHODS

The IMPROVE is a multicenter European study (n = 3,711). The association of plasma IL-8 with c-IMT (mm) was estimated by quantile regression. Genotyping was performed using the Illumina CardioMetabo and Immuno chips. Replication was attempted in three independent studies and a meta-analysis was performed using a random model.

RESULTS

In IMPROVE, each unit increase in plasma IL-8 was associated with an increase in median c-IMT measures (all p<0·03) in multivariable analyses. Linear regression identified rs117518778 and rs8057084 as associated with IL-8 levels and with measures of c-IMT. The two SNPs were combined in an IL-8-increasing genetic risk that showed causality of IL-8 on c-IMT in IMPROVE and in the UK Biobank (n = 22,179). The effect of IL-8 on c-IMT measures was confirmed in PIVUS (n = 1,016) and MDCCC (n = 6,103). The association of rs8057084 with c-IMT was confirmed in PIVUS and UK Biobank with a pooled estimate effect (β) of -0·006 with 95%CI (-0·008- -0·003).

CONCLUSION

Our results indicate that genetic variants associated with plasma IL-8 also associate with c-IMT. However, we cannot infer causality of this association, as these variants lie outside of the IL8 locus.

Increased IL-26 associates with markers of hyperinflammation and tissue damage in patients with acute COVID-19

Interleukin-26 (IL-26) is released by several immune and structural cells following stimulation of toll-like receptors (TLRs), whereupon it can directly inhibit viral replication and enhance neutrophil chemotaxis. Given these unique properties, IL-26 has emerged as an intriguing mediator of host defense in the lungs. However, the role of IL-26 in COVID-19 has not been thoroughly investigated. Here, we characterized the involvement of IL-26 in the hyperinflammation and tissue damage that occurs in patients with acute COVID-19. We found that IL-26 is markedly increased in blood samples from these patients, and that the concentration of IL-26 correlates with those of the neutrophil-mobilizing cytokines IL-8 and TNFα, respectively. Moreover, the increase in blood IL-26 correlates with enhanced surface expression of the “don’t eat me” signal CD47 on blood neutrophils isolated from patients with acute COVID-19. Finally, we found that the blood concentration of IL-26 correlates with that of increased lactate dehydrogenase, an established marker of tissue damage, and decreased mean corpuscular hemoglobin (MCH), a previously verified hematological aberration in COVID-19, both of which are associated with severe disease. Thus, our findings indicate that increased systemic IL-26 associates with markers of hyperinflammation and tissue damage in patients with acute COVID-19, thereby forwarding the kinocidin IL-26 as a potential target for diagnosis, monitoring, and therapy in this deadly disease.

Involvement of IL-26 in bronchiolitis obliterans syndrome but not in acute rejection after lung transplantation

BACKGROUND

 The main long-term complication after lung transplantation is bronchiolitis obliterans syndrome (BOS), a deadly condition in which neutrophils may play a critical pathophysiological role. Recent studies show that the cytokine interleukin IL-26 can facilitate neutrophil recruitment in response to pro-inflammatory stimuli in the airways. In this pilot study, we characterized the local involvement of IL-26 during BOS and acute rejection (AR) in human patients.

METHOD

 From a biobank containing bronchoalveolar lavage (BAL) samples from 148 lung transplant recipients (LTR), clinically-matched patient pairs were identified to minimize the influence of clinical confounders. We identified ten pairs (BOS/non-BOS) with BAL samples harvested on three occasions for our longitudinal investigation and 12 pairs of patients with and without AR. The pairs were matched for age, gender, preoperative diagnosis, type of and time after surgery. Extracellular IL-26 protein was quantified in cell-free BAL samples using an enzyme-linked immunosorbent assay. Intracellular IL-26 protein in BAL cells was determined using immunocytochemistry (ICC) and flow cytometry.

RESULTS

 The median extracellular concentration of IL-26 protein was markedly increased in BAL samples from patients with BOS (p < 0.0001) but not in samples from patients with AR. Intracellular IL-26 protein was confirmed in alveolar macrophages and lymphocytes (through ICC and flow cytometry) among BAL cells obtained from BOS patients.

CONCLUSIONS

 Local IL-26 seems to be involved in BOS but not AR, and macrophages as well as lymphocytes constitute cellular sources in this clinical setting. The enhancement of extracellular IL-26 protein in LTRs with BOS warrants further investigation of its potential as a target for diagnosing, monitoring, and treating BOS.

Biomarkers, Clinical Course, and Individual Needs in COPD Patients in Primary Care: The Study Protocol of the Stockholm COPD Inflammation Cohort (SCOPIC)

Background

To facilitate effective personalized medicine, primary health care needs better methods of assessing and monitoring chronic obstructive pulmonary disease (COPD).

Aim

This cohort study aims to investigate how biomarkers relate to clinical characteristics and COPD patients' subjective needs over time.

Methods

Patients (n=750) in different COPD severity according to the GOLD criteria and age- and sex-matched controls (n=750) will be recruited over a period of 5 years from 15 primary health care centers in Region Stockholm, Sweden, and followed for 10 years in the first instance. Data on patients' subjective needs will be collected via telephone/email, data on clinical/physiological variables (eg, symptoms, exacerbations, comorbidities, medications, smoking habits, lung function) from existing databases that are based on medical records, and data on biomarkers via repeated blood sampling. Quantitative and qualitative methods will be used. Initial results are expected after 2 years (feasibility test), and a larger body of evidence after 5 years.

Discussion

The study is expected to provide definitive and clinically useful scientific evidence about how biomarkers relate to clinical variables and patients' subjective needs. This new evidence will facilitate accurate, and personalized COPD management by the use of valid biomarkers. It will provide useful tools for primary care professionals and may facilitate optimal self-management.

Increased cytotoxic T-cells in the airways of adults with former bronchopulmonary dysplasia

Rationale

Bronchopulmonary dysplasia (BPD) in preterm-born infants is a risk factor for chronic airway obstruction in adulthood. Cytotoxic T-cells are implicated in COPD, but their involvement in BPD is not known.

Objectives

To characterise the distribution of airway T-cell subsets in adults with a history of BPD.

Methods

Young adults with former BPD (n=22; median age 19.6 years), age-matched adults born preterm (n=22), patients with allergic asthma born at term (n=22) and healthy control subjects born at term (n=24) underwent bronchoalveolar lavage (BAL). T-cell subsets in BAL were analysed using flow cytometry.

Results

The total number of cells and the differential cell counts in BAL were similar among the study groups. The percentage of CD3⁺CD8⁺ T-cells was higher (p=0.005) and the proportion of CD3⁺CD4⁺ T-cells was reduced (p=0.01) in the BPD group, resulting in a lower CD4/CD8 ratio (p=0.007) compared to the healthy controls (median 2.2 versus 5.3). In BPD and preterm-born study subjects, both CD3⁺CD4⁺ T-cells (r_s=0.38, p=0.03) and CD4/CD8 ratio (r_s=0.44, p=0.01) correlated positively with forced expiratory volume in 1 s (FEV₁). Furthermore, CD3⁺CD8⁺ T-cells were negatively correlated with both FEV₁ and FEV₁/forced vital capacity (r_s= −0.44, p=0.09 and r_s= −0.41, p=0.01, respectively).

Conclusions

Young adults with former BPD have a T-cell subset pattern in the airways resembling features of COPD. Our findings are compatible with the hypothesis that CD3⁺CD8⁺ T-cells are involved in mechanisms behind chronic airway obstruction in these patients.

Young adults with former BPD display more cytotoxic T-cells in the airways than healthy subjects. These T-cells correlate with FEV₁. Thus, cytotoxic T-cells may contribute to the pathology behind chronic airway obstruction in adults with former BPD.https://bit.ly/3soI4lK

IL-26 in asthma and COPD

INTRODUCTION

New targets are needed to enable more accurate diagnosis, monitoring and effective therapy in uncontrolled asthma and chronic obstructive pulmonary disease (COPD), two disorders characterized by pathogenic alterations in the innate immune response. Interestingly, the IL-10-related cytokine IL-26 has been found to be abundantly expressed in human airways and alterations in its expression have been linked to reduced lung function and markers of neutrophilic inflammation in patients with uncontrolled asthma or COPD.

AREAS COVERED

Literature search was conducted on PubMed to identify articles in the field of IL-26 immunology, as well as clinical studies on IL-26 in asthma and COPD, published between 2000 and 2021. We outline the main sources of IL-26 in human airways, as well as the effect of this cytokine on relevant immune and structural cells. Finally, we discuss the potential involvement of IL-26 in the pathophysiology of uncontrolled asthma and COPD.

EXPERT OPINION

IL-26 constitutes a potential target for diagnostic purposes and therapeutic modulation of the innate immune response in the airways of patients with asthma and COPD. It seems reasonable to expect more conclusive evidence of its clinical utility for personalized medicine within the coming 5-year period.

[Pharmacological treatment reduces mortality in COPD]

Approximately 500 000 individuals in Sweden have chronic obstructive pulmonary disease (COPD). Co-morbid, especially cardiovascular, conditions are common in COPD and globally COPD is the third most common cause of mortality. Mortality in COPD is driven by dyspnea, exacerbations and comorbidities and is reduced by smoking cessation and lung rehabilitation. Also, pharmacological treatment, in particular inhaled corticosteroids, reduces mortality in COPD. The reduction in mortality that can be achieved by treatment with inhaled corticosteroids in combinations with long-acting bronchodilators is of the same order of magnitude as the effect on mortality by treatment of hyperlipidemia and hypertension.

Complex Involvement of Interleukin-26 in Bacterial Lung Infection

Pneumonia is a global cause of mortality, and this provides a strong incentive to improve the mechanistic understanding of innate immune responses in the lungs. Here, we characterized the involvement of the cytokine interleukin (IL)-26 in bacterial lung infection. We observed markedly increased concentrations of IL-26 in lower airway samples from patients with bacterial pneumonia and these correlated with blood neutrophil concentrations. Moreover, pathogen-associated molecular patterns (PAMPs) from both Gram-negative and -positive bacteria increased extracellular IL-26 concentrations in conditioned media from human models of alveolar epithelial cells, macrophages, and neutrophils in vitro. Stimulation with IL-26 inhibited the inherent release of neutrophil elastase and myeloperoxidase in unexposed neutrophils. This stimulation also inhibited the expression of activity makers in neutrophils exposed to Klebsiella pneumoniae. In addition, priming of human lung tissue ex vivo with exogenous IL-26 potentiated the endotoxin-induced increase in mRNA for other cytokines involved in the innate immune response, including the master Th17-regulator IL-23 and the archetype inhibitory cytokine IL-10. Finally, neutralization of endogenous IL-26 clearly increased the growth of Klebsiella pneumoniae in the macrophage culture. These findings suggest that IL-26 is involved in bacterial lung infection in a complex manner, by modulating critical aspects of innate immune responses locally and systemically in a seemingly purposeful manner and by contributing to the killing of bacteria in a way that resembles an antimicrobial peptide. Thus, IL-26 displays both diagnostic and therapeutic potential in pneumonia and deserves to be further evaluated in these respects.

Occupational exposure to particles and increased risk of developing chronic obstructive pulmonary disease (COPD): A population-based cohort study in Stockholm, Sweden

OBJECTIVES

Chronic Obstructive Pulmonary Disease (COPD) is a common respiratory disorder. Next to tobacco smoking, occupational exposure is the most important risk factor for COPD in high-income countries. To enable preventative measures, more knowledge is needed on which specific occupational exposures that are related to risk of developing COPD in men and women.

METHODS

A population-based cohort was formed from subjects responding to the Stockholm Public Health Surveys in 2002, 2006, and 2010, followed up until 2014. The dataset was linked to a quantitative job exposure matrix via occupational titles from the 1990 nation-wide Population and housing census. We identified COPD among subjects having medication for COPD and/or reporting a physician's diagnosis of COPD. The gender-specific risks to develop COPD from occupational particle-exposure were estimated by proportional hazards regression model, adjusted for age and individual data on tobacco-smoking.

RESULTS

Men exposed to respirable crystalline silica (RCS) (HR 1.46, CI 1.13-1.90), gypsum and insulation material (HR 1.56, CI 1.18-2.05), diesel exhaust (HR 1.18, CI 0.99-1.41) and high levels of particles from asphalt/bitumen (HR 1.71, CI 1.06-2.76) as well as welding fumes (HR 1.57, CI 1.12-2.21) had an increased smoking-adjusted risk for developing COPD. An increased risk was also observed among women highly exposed to various organic particles from soil, leather, plastic, soot, animal, textile, flour (HR 1.53, CI 1.15-2.04). Furthermore, a significant positive exposure-response trend was found among men exposed to RCS, iron dust, gypsum and insulation material, and diesel exhaust. A tendency towards an exposure-response relationship was also seen among both men and women exposed to welding fumes and various organic particles, and among men exposed to particles from asphalt/bitumen. The population attributable fraction for COPD from occupational exposure to particles was 10.6% among men and 6.1% among women.

CONCLUSIONS

This study indicates an increased smoking-adjusted risk of developing of COPD due to occupational exposure to particles. A positive exposure-response relationship was found for RCS, gypsum and insulation, diesel exhaust, and welding fumes. Also, exposure to high levels of asphalt/bitumen and various organic particles was associated with a higher risk for COPD. Reduction of these exposures in the work environment are important to prevent future cases of COPD. More studies are needed to investigate exposure-response relationships further, but this study indicates that the European occupational exposure limit (OEL) for RCS needs to be re-evaluated.

Mucin Binding to Moraxella catarrhalis During Airway Inflammation is Dependent on Sialic Acid

Chronic obstructive pulmonary disease (COPD) is associated with colonization by bacterial pathogens and repeated airway infections, leading to exacerbations and impaired lung function. The highly glycosylated mucins in the mucus lining the airways are an important part of the host defense against pathogens. However, mucus accumulation can contribute to COPD pathology. Here, we examined whether inflammation is associated with glycosylation changes that affect interactions between airway mucins and pathogens. We isolated mucins from lower airway samples (LAS, n=4-9) from long-term smokers with and without COPD and from never-smokers. The most abundant terminal glycan moiety was N-acetylneuraminic acid (Neu5Ac) among smokers with and without COPD and N-acetyl-hexoseamine among never-smokers. Moraxella catarrhalis bound to MUC5 mucins from smokers with and without COPD. M. catarrhalis binding correlated with inflammatory parameters and Neu5Ac content. M. catarrhalis binding was abolished by enzymatic removal of Neu5Ac. Furthermore, M. catarrhalis bound to α2-6 sialyl-lactose suggesting that α2-6 sialic acid contributes to M. catarrhalis binding to mucins. Further, we detected more M. catarrhalis binding to mucins from patients with pneumonia than to those from control subjects (n=8-13) and this binding correlated with C-reactive protein and Neu5Ac levels. These results suggest a key role of inflammation induced Neu5Ac in adhesion of M. catarrhalis to airway mucins. Inflammation induced ability of MUC5 mucins to bind M. catarrhalis is likely a host defense mechanism in the healthy lung, although it cannot be excluded that impaired mucociliary clearance limits the effectiveness of this defense in COPD patients.

Chronic airflow limitation and its relation to respiratory symptoms among ever-smokers and never-smokers: a cross-sectional study

BACKGROUND

The diagnosis of chronic obstructive pulmonary disease is based on the presence of persistent respiratory symptoms and chronic airflow limitation (CAL). CAL is based on the ratio of forced expiratory volume in 1 s to forced vital capacity (FEV₁:FVC) after bronchodilation, and FEV₁:FVC less than the fifth percentile is often used as a cut-off for CAL. The aim was to investigate if increasing percentiles of FEV₁:FVC were associated with any respiratory symptom (cough with phlegm, dyspnoea or wheezing) in a general population sample of never-smokers and ever-smokers.

METHODS

In a cross-sectional study comprising 15 128 adults (50-64 years), 7120 never-smokers and 8008 ever-smokers completed a respiratory questionnaire and performed FEV₁ and FVC after bronchodilation. We calculated their z-scores for FEV₁:FVC and defined the fifth percentile using the Global Lung Function Initiative (GLI) reference value, GLI₅ and increasing percentiles up to GLI₂₅. We analysed the associations between different strata of percentiles and prevalence of any respiratory symptom using multivariable logistic regression for estimation of OR.

RESULTS

Among all subjects, regardless of smoking habits, the odds of any respiratory symptom were elevated up to the GLI_15-20 strata. Among never-smokers, the odds of any respiratory symptom were elevated at GLI_<5 (OR 3.57, 95% CI 2.43 to 5.23) and at GLI_5-10 (OR 2.57, 95% CI 1.69 to 3.91), but not at higher percentiles. Among ever-smokers, the odds of any respiratory symptom were elevated from GLI_<5 (OR 4.64, 95% CI 3.79 to 5.68) up to GLI_≥25 (OR 1.33, 95% CI 1.00 to 1.75).

CONCLUSIONS

The association between percentages of FEV₁:FVC and respiratory symptoms differed depending on smoking history. Our results support a higher percentile cut-off for FEV₁:FVC for never-smokers and, in particular, for ever-smokers.

Heparin-binding protein in lower airway samples as a biomarker for pneumonia

Objectives

Ventilator-associated pneumonia (VAP) is difficult to diagnose using clinical criteria and no biomarkers have yet been proved to be sufficiently accurate. The use of the neutrophil-derived Heparin-binding protein (HBP) as a biomarker for pneumonia was investigated in this exploratory case–control study in two intensive care units at a tertiary referral hospital.

Methods

Patients with clinical signs of pneumonia were recruited and bronchoalveolar lavage fluid (BALF) or bronchial wash (BW) samples were collected. Mechanically ventilated and lung healthy subjects were recruited as controls. HBP was measured with enzyme-linked immunosorbent assay.

Results

BALF was collected from 14 patients with pneumonia and 14 healthy controls. Median HBP in BALF pneumonia samples was 14,690 ng/ml and controls 16.2 ng/ml (p < 0.0001). BW was collected from 10 pneumonia patients and 10 mechanically ventilated controls. Median HBP in BW pneumonia was 9002 ng/ml and controls 7.6 ng/ml (p < 0.0001).

Conclusions

These data indicate that HBP concentrations is significantly higher in lower airway samples from patients with pneumonia than control subjects and is a potentially useful biomarker for diagnosis of VAP.

Assessment of chronic bronchitis and risk factors in young adults: results from BAMSE

Background

Chronic bronchitis is associated with substantial morbidity among elderly adults, but little is known about its prevalence and risk factors in young adults. Our aim was to assess the prevalence and early-life risk factors for chronic bronchitis in young adults.

Methods

Questionnaire data and clinical measures from the 24-year follow-up of the Swedish BAMSE (Child (Barn), Allergy, Milieu, Stockholm, Epidemiological) cohort were used. We assessed chronic bronchitis (CB) as the combination of cough and mucus production in the morning during winter. Environmental and clinical data from birth and onwards were used for analyses of risk factors.

Results

At the 24-year follow-up, 75% (n=3064) participants completed the questionnaire and 2030 performed spirometry. The overall prevalence of CB was 5.5% (n=158) with similar estimates in males and females. 49% of CB cases experienced more than three self-reported respiratory infections in the past year compared to 18% in non-CB subjects (p<0.001), and 37% of cases were current smokers (versus 19% of non-CB cases). Statistically significant lower post-bronchodilator forced expiratory volume in 1 s/forced vital capacity were observed in CB compared to non-CB subjects (mean z-score −0.06 versus 0.13, p=0.027). Daily smoking (adjusted (a)OR 3.85, p<0.001), air pollution exposure (black carbon at ages 1–4 years aOR 1.71 per 1 μg·m⁻³ increase, p=0.009) and exclusive breastfeeding for ≤4 months (aOR 0.66, p=0.044) were associated with CB.

Conclusion

Chronic bronchitis in young adults is associated with recurrent respiratory infections. Besides smoking, our results support the role of early-life exposures, such as air pollution and exclusive breastfeeding, for respiratory health later in life.

Chronic bronchitis in young adults is strongly associated with recurrent respiratory infections. Besides smoking, our results support the role of early-life environmental exposures for respiratory health in this age group.https://bit.ly/2RNsv5z

IL-36 Cytokines Promote Inflammation in the Lungs of Long-Term Smokers

Chronic obstructive pulmonary disease (COPD) is a progressive inflammatory lung disease with high morbidity and mortality. The IL-36 family are proinflammatory cytokines that are known to shape innate immune responses, including those critical to bacterial pneumonia. The objective of this study was to determine whether IL-36 cytokines promote a proinflammatory milieu in the lungs of long-term smokers with and without COPD. Concentrations of IL-36 cytokines were measured in plasma and BAL fluid from subjects in a pilot study (n = 23) of long-term smokers with and without COPD in vivo and from a variety of lung cells (from 3-5 donors) stimulated with bacteria or cigarette smoke components in vitro. Pulmonary macrophages were stimulated with IL-36 cytokines in vitro, and chemokine and cytokine production was assessed. IL-36α and IL-36γ are produced to varying degrees in murine and human lung cells in response to bacterial stimuli and cigarette smoke components in vitro. Moreover, whereas IL-36γ production is upregulated early after cigarette smoke stimulation and wanes over time, IL-36α production requires a longer duration of exposure. IL-36α and IL-36γ are enhanced systemically and locally in long-term smokers with and without COPD, and local IL-36α concentrations display a positive correlation with declining ventilatory lung function and increasing proinflammatory cytokine concentrations. In vitro, IL-36α and IL-36γ induce proinflammatory chemokines and cytokines in a concentration-dependent fashion that requires IL-36R and MyD88. IL-36 cytokine production is altered in long-term smokers with and without COPD and contributes to shaping a proinflammatory milieu in the lungs.

Systemic Galectin-3 in Smokers with Chronic Obstructive Pulmonary Disease and Chronic Bronchitis: The Impact of Exacerbations

Purpose

The carbohydrate-binding protein Galectin-3 is increased in several inflammatory diseases and has recently been forwarded as a systemic biomarker in chronic obstructive pulmonary disease (COPD). In this longitudinal study, we characterized the level of systemic Galectin-3 using blood from smokers with a history of COPD and chronic bronchitis (COPD-CB), during stable clinical conditions and exacerbations.

Patients and Methods

The study population comprised 56 long-term smokers with COPD-CB, 10 long-term smokers without lung disease (LTS) and 10 clinically healthy never-smokers (HNS). Blood samples were analyzed for levels of Galectin-3, leukocyte populations and C-reactive protein (CRP). In addition, sputum samples from the COPD-CB group were analyzed for bacterial growth.

Results

When comparing stable clinical conditions and exacerbations in the COPD-CB group, we found that the level of Galectin-3, just like that of CRP, leukocytes and neutrophils, respectively, was increased during exacerbations. However, this exacerbation-associated increase of Galectin-3 was modest. During stable clinical conditions of COPD-CB, the level of Galectin-3 was not elevated in comparison with HNS or LTS. Nor did this level of Galectin-3 distinguish patients that remained in a clinically stable condition throughout the study to those that developed an exacerbation. In addition, neither during stable clinical conditions nor during exacerbations, did the presence of bacterial growth in sputum alter Galectin-3 levels. In contrast to Galectin-3, the level of CRP, leukocytes and neutrophils, respectively, were increased during clinical stable conditions in the COPD-CB group compared with the other groups and were further enhanced during exacerbations.

Conclusion

Systemic Galectin-3 is increased in a reproducible but modest manner during exacerbations in smokers with COPD-CB. During stable clinical conditions, the level of systemic Galectin-3 does not distinguish patients that remain clinically stable from those that develop exacerbations. This makes it less likely that systemic Galectin-3 may become a clinically useful biomarker in the current setting.

The ratio FEV1 /FVC and its association to respiratory symptoms-A Swedish general population study

Chronic airflow limitation (CAL) can be defined as fixed ratio of forced expiratory volume in 1 s (FEV₁)/forced vital capacity (FVC) < 0.70 after bronchodilation. It is unclear which is the most optimal ratio in relation to respiratory morbidity. The aim was to investigate to what extent different ratios of FEV₁/FVC were associated with any respiratory symptom. In a cross‐sectional general population study, 15,128 adults (50–64 years of age), 7,120 never‐smokers and 8,008 ever‐smokers completed a respiratory questionnaire and performed FEV₁ and FVC after bronchodilation. We calculated different ratios of FEV₁/FVC from 0.40 to 1.0 using 0.70 as reference category. We analysed odds ratios (OR) between different ratios and any respiratory symptom using adjusted multivariable logistic regression. Among all subjects, regardless of smoking habits, the lowest odds for any respiratory symptom was at FEV₁/FVC = 0.82, OR 0.48 (95% CI 0.41–0.56). Among never‐smokers, the lowest odds for any respiratory symptom was at FEV₁/FVC = 0.81, OR 0.53 (95% CI 0.41–0.70). Among ever‐smokers, the odds for any respiratory symptom was lowest at FEV₁/FVC = 0.81, OR 0.43 (95% CI 0.16–1.19), although the rate of inclining in odds was small in the upper part, that is FEV₁/FVC = 0.85 showed similar odds, OR 0.45 (95% CI 0.38–0.55). We concluded that the odds for any respiratory symptoms continuously decreased with higher FEV₁/FVC ratios and reached a minimum around 0.80–0.85, with similar results among never‐smokers. These results indicate that the optimal threshold associated with respiratory symptoms may be higher than 0.70 and this should be further investigated in prospective longitudinal studies.

Interleukin-26 in host defense and inflammatory disorders of the airways

The dimeric cytokine interleukin (IL)-26 belongs to the IL-10 family. Whereas it was originally perceived as a T-helper (Th)17 cytokine, subsequent studies have shown that IL-26 is produced by several populations of leukocytes and structural cells. This cytokine binds to a heterodimeric receptor complex including IL-10R2 and -20R1 (IL-26R) and signals through STAT 1 and 3 to induce the release of chemokines and growth factors. Remarkably, IL-26 directly kills bacteria and inhibits viral replication. The most recent studies on human airways confirm multiple cellular sources in this critical interphase of host defense and demonstrate that stimulation of toll-like receptors (TLR) trigger the release of IL-26. Once released, it exerts a dualistic effect on cytokine production and up-regulates gene expression of IL-26R. It also potentiates chemotaxis and inhibits chemokinesis for neutrophils, thereby facilitating the accumulation of innate effector cells at the site of bacterial stimulation. The high levels of IL-26 in human airways are altered in inflammatory airway disorders such as asthma and chronic obstructive pulmonary disease. Thus, IL-26 emerges as an important mediator, providing direct and indirect actions on microbes, actions that are essential for host defense and inflammation and bears potential as a biomarker of disease.

Early-life risk factors for reversible and irreversible airflow limitation in young adults: findings from the BAMSE birth cohort

We aimed to determine prevalence and early-life risk factors for reversible and irreversible airflow limitation in young adults from the general population. Among young adults in their 20s, the prevalence was 5.3% for reversible airflow limitation and 2.0% for irreversible airflow limitation. While parental asthma was the only risk factor for development of reversible airflow limitation, the risk factors for development of irreversible airflow limitation were current asthma, childhood respiratory tract infections and asthma, and exposure to air pollution.

[The role of inhaled steroids in the treatment of COPD]

The aim of COPD treatment is to reduce symptoms and prevent exacerbations. The pharmacological treatment is based on bronchodilator treatment which reduces symptoms and prevents exacerbations. If patients have exacerbations despite bronchodilator treatment it is important to consider adding inhaled corticosteroids (ICS). Concomitant asthma is always an indication for ICS treatment. Studies have shown that measurement of blood eosinophil count predicts the effect of adding ICS to bronchodilators. Higher b-eos (≥ 0,3 × 109/l) strengthens the indication for ICS. A large number of COPD patients in Sweden are treated with both bronchodilators and ICS without a history of exacerbations. It is important to assess that the indication is correct at follow up of these patients.

Increased CD11b and Decreased CD62L in Blood and Airway Neutrophils from Long-Term Smokers with and without COPD

There is incomplete mechanistic understanding of the mobilization of neutrophils in the systemic and local compartment in smokers with chronic obstructive pulmonary disease (COPD). In this pilot study, we characterized how the adhesion molecules CD11b and CD62L, surface markers indicative of priming, are altered as neutrophils extravasate, and whether surface density of CD11b and CD62L differs between long-term tobacco smokers (LTS) with and without COPD compared with healthy never-smokers (HNS). Unstimulated blood neutrophils from LTS with (n = 5) and without (n = 9) COPD displayed lower surface density of CD62L compared with HNS (n = 8). In addition, surface density of CD11b was higher in bronchoalveolar lavage (BAL) neutrophils from LTS without COPD compared with those with COPD and HNS. Moreover, in BAL neutrophils from all study groups, CD62L was lower compared with matched blood neutrophils. In addition, BAL neutrophils responded with a further decrease in CD62L to ex vivo TNF stimulation. Thus, neutrophils in the airway lumen display a higher state of priming than systemic neutrophils and bear the potential to be further primed by local cytokines even with no smoking or the presence of COPD, findings that may represent a universal host defense mechanism against local bacteria. Moreover, systemic neutrophils are primed in LTS regardless of COPD. Further studies in larger materials are warranted to determine whether the priming of neutrophils is protective against COPD or merely preceding it.

Disentangling the Amyloid Pathways: A Mechanistic Approach to Etiology

Amyloids are fibrillar protein aggregates associated with diseases such as Alzheimer's disease (AD), Parkinson's disease (PD), type II diabetes and Creutzfeldt-Jakob disease. The process of amyloid polymerization involves three pathological protein transformations; from natively folded conformation to the cross-β conformation, from biophysically soluble to insoluble, and from biologically functional to non-functional. While amyloids share a similar cross-β conformation, the biophysical transformation can either take place spontaneously via a homogeneous nucleation mechanism (HON) or catalytically on an exogenous surface via a heterogeneous nucleation mechanism (HEN). Here, we postulate that the different nucleation pathways can serve as a mechanistic basis for an etiological classification of amyloidopathies, where hereditary forms generally follow the HON pathway, while sporadic forms follow seed-induced (prions) or surface-induced (including microbially induced) HEN pathways. Critically, the conformational and biophysical amyloid transformation results in loss-of-function (LOF) of the original natively folded and soluble protein. This LOF can, at least initially, be the mechanism of amyloid toxicity even before amyloid accumulation reaches toxic levels. By highlighting the important role of non-protein species in amyloid formation and LOF mechanisms of toxicity, we propose a generalized mechanistic framework that could help better understand the diverse etiology of amyloid diseases and offer new opportunities for therapeutic interventions, including replacement therapies.

Studies on citrullinated LL-37: detection in human airways, antibacterial effects and biophysical properties

Arginine residues of the antimicrobial peptide LL-37 can be citrullinated by peptidyl arginine deiminases, which reduce the positive charge of the peptide. Notably, citrullinated LL-37 has not yet been detected in human samples. In addition, functional and biophysical properties of citrullinated LL-37 are not fully explored. The aim of this study was to detect citrullinated LL-37 in human bronchoalveolar lavage (BAL) fluid and to determine antibacterial and biophysical properties of citrullinated LL-37. BAL fluid was obtained from healthy human volunteers after intra-bronchial exposure to lipopolysaccharide. Synthetic peptides were used for bacterial killing assays, transmission electron microscopy, isothermal titration calorimetry, mass-spectrometry and circular dichroism. Using targeted proteomics, we were able to detect both native and citrullinated LL-37 in BAL fluid. The citrullinated peptide did not kill Escherichia coli nor lysed human red blood cells. Both peptides had similar α-helical secondary structures but citrullinated LL-37 was more stable at higher temperatures, as shown by circular dichroism. In conclusion, citrullinated LL-37 is present in the human airways and citrullination impaired bacterial killing, indicating that a net positive charge is important for antibacterial and membrane lysing effects. It is possible that citrullination serves as a homeostatic regulator of AMP-function by alteration of key functions.

Pulmonary outcomes in adults with a history of Bronchopulmonary Dysplasia differ from patients with asthma

Background

Bronchopulmonary dysplasia (BPD) is a risk factor for respiratory disease in adulthood. Despite the differences in underlying pathology, patients with a history of BPD are often treated as asthmatics. We hypothesized that pulmonary outcomes and health-related quality of life (HRQoL) were different in adults born preterm with and without a history of BPD compared to asthmatics and healthy individuals.

Methods

We evaluated 96 young adults from the LUNAPRE cohort (clinicaltrials.gov/ct2/show/NCT02923648), including 26 individuals born preterm with a history of BPD (BPD), 23 born preterm without BPD (preterm), 23 asthmatics and 24 healthy controls. Extensive lung function testing and HRQoL were assessed.

Results

The BPD group had more severe airway obstruction compared to the preterm-, (FEV₁₋ 0.94 vs. 0.28 z-scores; p ≤ 0.001); asthmatic- (0.14 z-scores, p ≤ 0.01) and healthy groups (0.78 z-scores, p ≤ 0.001). Further, they had increased ventilation inhomogeneity compared to the preterm- (LCI 6.97 vs. 6.73, p ≤ 0.05), asthmatic- (6.75, p = 0.05) and healthy groups (6.50 p ≤ 0.001). Both preterm groups had lower D_LCO compared to healthy controls (p ≤ 0.001 for both). HRQoL showed less physical but more psychological symptoms in the BPD group compared to asthmatics.

Conclusions

Lung function impairment and HRQoL in adults with a history of BPD differed from that in asthmatics highlighting the need for objective assessment of lung health.

Electronic supplementary material

The online version of this article (10.1186/s12931-019-1075-1) contains supplementary material, which is available to authorized users.

Bacterial Outer Membrane Vesicles Induce Vitronectin Release Into the Bronchoalveolar Space Conferring Protection From Complement-Mediated Killing

Pathogens causing pneumonia utilize the complement regulator vitronectin to evade complement-mediated killing. Although vitronectin is associated with several chronic lung diseases, the role of bronchoalveolar vitronectin in pneumonia has not been studied. This study sought to reveal the involvement of vitronectin in the bronchoalveolar space during pneumonia, to assess the effect of outer membrane vesicles and endotoxin on vitronectin release, and to determine whether bacterial pathogens utilize pulmonary vitronectin for evasion. Vitronectin was analyzed in cell-free bronchoalveolar lavage fluid harvested from patients with pneumonia (n = 8) and from healthy volunteers after subsegmental endotoxin instillation (n = 13). Vitronectin binding by Pseudomonas aeruginosa and Haemophilus influenzae was analyzed, and subsequent complement evasion was assessed by serum challenge. The effects of outer membrane vesicles on vitronectin production in mouse lungs and human type II alveolar epithelial cells (A549) were determined. We detected increased vitronectin concentrations in lavage fluid during pneumonia (p = 0.0063) and after bronchial endotoxin challenge (p = 0.016). The capture of vitronectin by bacteria significantly reduced complement-mediated lysis. Following challenge with vesicles, vitronectin was detected in mouse bronchoalveolar space, and mouse alveolar epithelial cells in vivo as well as A549 cells in vitro contained increased levels of vitronectin. Taken together, outer membrane vesicles and endotoxin from Gram-negative bacteria induce vitronectin, which is released into the bronchoalveolar space, and used for evasion of complement-mediated clearance.

Cadmium in tobacco smokers: a neglected link to lung disease?

Cadmium in tobacco smoke may contribute to the development of pulmonary emphysema. However, there is poor understanding of the mechanisms behind the pathogenic role of cadmium in this and other smoking-related lung diseases. The traditional focus on the total body burden of cadmium, estimated through analysis of urine, may not fully reflect the local burden of cadmium, since it is inhaled by smokers. Thus, assessing the local accumulation of cadmium in the lungs appears more relevant, given that there is tissue-specific retention of cadmium.

In this review, we outline the principal sources of cadmium exposure and the clinical effects of occupational exposure. In addition, we review evidence on local cadmium and its association with alterations in innate immunity in tobacco smokers. Moreover, we scrutinise the data on cadmium as a cause of lung disease in translational models.

We conclude that cadmium may contribute to smoking-related lung diseases, possibly via an altered redox balance and by making macrophages dysfunctional. However, there is a need for new studies on local cadmium levels and their relation to pathology in long-term tobacco smokers, as well as for more in-depth studies on cellular and molecular mechanisms, to elucidate the importance of cadmium in smoking-related lung diseases.

Cadmium in tobacco smoke emerges as a potentially important pathogenic factor in smoking-related lung diseasehttp://ow.ly/msOm30irmg7

Recombinant human IL-26 facilitates the innate immune response to endotoxin in the bronchoalveolar space of mice in vivo

Interleukin (IL)-26 is released in response to bacterial endotoxin (LPS) in the bronchoalveolar space of humans in vivo and it may potentiate neutrophil chemotaxis by enhanced IL-26 receptor stimulation. However, the effects of extracellular IL-26 protein on the innate immune response in the lungs in vivo remain unknown. Here, we characterized these effects of IL-26 on a wide range of aspects of the innate immune response to LPS in different compartments of the lungs in vivo over time. We administrated recombinant human (rh) IL-26 protein in the bronchoalveolar space using intranasal instillation in a mouse in vivo model, with and without prior instillation of LPS. We verified gene expression of the IL-26 receptor complex in mouse lungs and observed that, after instillation of LPS, rhIL-26 increases the phosphorylation of STAT3, a signaling molecule of the IL-26 receptor complex. We also observed that rhIL-26 exerted additional stimulatory and inhibitory actions that are compartment- and time-dependent, resulting in alterations of cytokines, proteinases, tissue inflammation and the accumulation of innate effector cells. Without the prior instillation of LPS, rhIL-26 exerted time-dependent effects on total gelatinase activity but few other effects. Most important, after instillation of LPS, rhIL-26 cleared inflammatory cells from local tissue and increased the accumulation of innate effector cells in the bronchoalveolar space. Tentatively, rhIL-26 may facilitate the innate immune response towards the bronchoalveolar space in vivo and represents a potential target for therapy in lung disorders involving the innate immune response.

In vivo adherence of Flavobacterium psychrophilum to mucosal external surfaces of rainbow trout (Oncorhynchus mykiss) fry

The adherence of Flavobacterium psychrophilum to surfaces of epithelial tissues has been inconclusively suggested as a mechanism, which enables the bacterium to invade the host. Hence, the present study aimed to examine the adherence of the cells of two colony phenotypes, smooth and rough, of F. psychrophilum to mucosal tissues of rainbow trout fry and to test the skin mucus as a nutrient for the growth of F. psychrophilum. Fish were immersed in water containing 10⁶  CFU  mL^-1 F. psychrophilum for each colony phenotype. Mucosal tissue samples from fins, gills, skin and eyes, and swab samples from spleen and kidney were taken and inoculated onto TYES agar plates. Colony phenotypes of F. psychrophilum were identified and number of colonies counted. The results showed that cells of both phenotypes initially (0 h) adhered to all mucosal surfaces, but only the rough cells were still present on tissues 1 h post-immersion. Both phenotypes showed a tissue tropism with the fin tissue being the most adhered. Furthermore, skin mucus promoted the growth of both colony phenotypes. We suggest that the growth of F. psychrophilum cells in skin mucus apparently facilitates the bacterial adherence to mucosal surfaces, and the subsequent invasion into the host.

Interleukin-26 Production in Human Primary Bronchial Epithelial Cells in Response to Viral Stimulation: Modulation by Th17 cytokines

Interleukin (IL)-26 is abundant in human airways and this cytokine is involved in the local immune response to a bacterial stimulus in vivo. Specifically, local exposure to the toll-like receptor (TLR) 4 agonist endotoxin does increase IL-26 in human airways and this cytokine potentiates chemotactic responses in human neutrophils. In addition to T-helper (Th) 17 cells, alveolar macrophages can produce IL-26, but it remains unknown whether this cytokine can also be produced in the airway mucosa per se in response to a viral stimulus. Here, we evaluated whether this is the case using primary bronchial epithelial cells from the airway epithelium in vitro, and exploring the signaling mechanisms involved, including the modulatory effects of additional Th17 cytokines. Finally, we assessed IL-26 and its archetype signaling responses in healthy human airways in vivo. We found increased transcription and release of IL-26 protein after stimulation with the viral-related double stranded (ds) RNA polyinosinic-polycytidylic acid (poly-IC) and showed that this IL-26 release involved mitogen-activated protein (MAP) kinases and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB). The release of IL-26 in response to a viral stimulus was modulated by additional Th17 cytokines. Moreover, there was transcription of IL26 mRNA and expression of the protein in epithelial cells of bronchial brush and tissue biopsies respectively after harvest in vivo. In addition, the extracellular IL-26 protein concentrations in bronchoalveolar lavage (BAL) samples did correlate with increased epithelial cell transcription of an archetype intracellular signaling molecule downstream of the IL-26-receptor complex, STAT1, in the bronchial brush biopsies. Thus, our study suggests that viral stimulation causes the production of IL-26 in lining epithelial cells of human airway structural cells that constitute a critical immune barrier and that this production is modulated by Th17 cytokines.

Endotoxin Exposure Increases LL-37 - but Not Calprotectin - in Healthy Human Airways

RATIONALE

The antimicrobial peptides (AMPs) LL-37 and calprotectin are important players in the innate immunity of human airways. In patients with diseases characterized by bacterial colonization, the airway concentrations of these AMPs are increased. Less is known about their presence and release patterns in healthy humans. Our aim was to determine whether LL-37 and calprotectin are released after the activation of the innate immune response in the peripheral airways.

METHODS

Healthy volunteers underwent exposure to endotoxin and vehicle in contralateral segment bronchi. After 12 or 24 h, samples of bronchoalveolar lavage fluid (BALf) were collected bilaterally from exposed segments. Cell and AMP concentrations were assessed, as were the pro-form and active form of LL-37.

RESULTS

Both LL-37 and calprotectin were detected in cell-free BALf from both endotoxin- and vehicle-exposed segments. The concentrations of precursor and active LL-37 and neutrophils were significantly higher in endotoxin-exposed segments after 12 and 24 h, and the concentrations of LL-37 and neutrophils correlated positively. The concentrations of calprotectin were not markedly affected by exposure to endotoxin.

CONCLUSIONS

Local endotoxin exposure elicits the release and activation of LL-37 but not calprotectin in healthy human peripheral airways, suggesting an inducible involvement of LL-37 in the local innate immune response.

Characterization of secondary care for COPD in Sweden

Introduction: Only a selected proportion of chronic obstructive pulmonary disease (COPD) patients are managed in secondary care. The aim of this study was to characterize disease severity, treatment and structure of secondary care for COPD in Sweden. Methods: Information was collected from 29 of 33 existing secondary care units of respiratory medicine in Sweden, using both individual data from 373 consecutively enrolled COPD patients with Global initiative on Obstructive Lung Disease (GOLD) stage III-IV and a structural questionnaire about available resources at the units. Patient data included exacerbations, health status assessed by COPD Assessment Test (CAT), lung function, comorbid conditions, pharmacological treatment and vaccinations. Structural data included available smoking cessation support, multidisciplinary rehabilitation, physical training, patient education and routine follow-up after exacerbations at the respective unit. All patients were reclassified according to the GOLD 2014 group A-D classification. Multiple linear regression investigated associations of available resources with number of exacerbations and CAT score. Results: According to GOLD 2014, 87% of the population were GOLD D and 13% were GOLD C. Triple inhaled therapy were prescribed in 88% of the patients. Over 75% of the units had resources for smoking cessation, multidisciplinary rehabilitation, physical training and patient education. Routine follow-up after exacerbations was available in 35% of the units. Being managed at units with access to structured patient education was associated with statistically significantly fewer exacerbations (adjusted regression coefficient (95% confidence interval) -0.79 (-1.39 to -0.19), p = 0.010). Conclusion: Most stage III-IV COPD patients managed at secondary care respiratory units in Sweden have maximized inhaled therapy and high risk disease even when reclassified according to GOLD 2014. Most units have access to smoking cessation, rehabilitation and patient education. Patients managed at units with structured patient education have a lower exacerbation risk.

Distinctive Regulatory T Cells and Altered Cytokine Profile Locally in the Airways of Young Smokers with Normal Lung Function

Smoking influences the immune system in different ways and, hypothetically, effects on pulmonary effector and regulatory T cells emerge as potentially detrimental. Therefore, we characterized the frequencies and characteristics of CD4+ and CD8+ T cell subsets in the blood and lungs of young tobacco smokers. Bronchoalveolar lavage (BAL) and peripheral blood were obtained from healthy moderate smokers (n = 18; 2–24 pack-years) and never-smokers (n = 15), all with normal lung function. Cells were stimulated ex vivo and key intracellular cytokines (IFNγ, IL-17, IL-10 and TNFα) and transcription factors (Foxp3, T-bet and Helios) were analyzed using flow cytometry. Our results indicate that smoking is associated with a decline in lung IL-17+ CD4+ T cells, increased IFNγ+ CD8+ T cells and these alterations relate to the history of daily cigarette consumption. There is an increased fraction of Foxp3+ regulatory T cells being Helios- in the lungs of smokers. Cytokine production is mainly confined to the Helios- T cells, both in regulatory and effector subsets. Moreover, we detected a decline of Helios+Foxp3- postulated regulatory CD8+ T cells in smokers. These alterations in the immune system are likely to increase risk for infection and may have implications for autoimmune processes initiated in the lungs among tobacco smokers.

Interleukin-16-producing NK cells and T-cells in the blood of tobacco smokers with and without COPD

Background

Long-term exposure to tobacco smoke causes local inflammation in the airways that involves not only innate immune cells, including NK cells, but also adaptive immune cells such as cytotoxic (CD8⁺) and helper (CD4⁺) T-cells. We have previously demonstrated that long-term tobacco smoking increases extracellular concentration of the CD4⁺-recruiting cytokine interleukin (IL)-16 locally in the airways. Here, we hypothesized that tobacco smoking alters IL-16 biology at the systemic level and that this effect involves oxygen free radicals (OFR).

Methods

We quantified extracellular IL-16 protein (ELISA) and intracellular IL-16 in NK cells, T-cells, B-cells, and monocytes (flow cytometry) in blood samples from long-term tobacco smokers with and without chronic obstructive pulmonary disease (COPD) and in never-smokers. NK cells from healthy blood donors were stimulated with water-soluble tobacco smoke components (cigarette smoke extract) with or without an OFR scavenger (glutathione) in vitro and followed by quantification of IL-16 protein.

Results

The extracellular concentrations of IL-16 protein in blood did not display any substantial differences between groups. Notably, intracellular IL-16 protein was detected in all types of blood leukocytes. All long-term smokers displayed a decrease in this IL-16 among NK cells, irrespective of COPD status. Further, both NK and CD4⁺ T-cell concentrations displayed a negative correlation with pack-years. Moreover, cigarette smoke extract caused release of IL-16 protein from NK cells in vitro, and this was not affected by glutathione, in contrast to the decrease in intracellular IL-16, which was prevented by this drug.

Conclusion

Long-term exposure to tobacco smoke does not markedly alter extracellular concentrations of IL-16 protein in blood. However, it does decrease the intracellular IL-16 concentrations in blood NK cells, the latter effect involving OFR. Thus, long-term tobacco smoking exerts an impact at the systemic level that involves NK cells; innate immune cells that are critical for host defense against viruses and tumors – conditions that are overrepresented among smokers.

Impact of tobacco smoking on cytokine signaling via interleukin-17A in the peripheral airways

There is excessive accumulation of neutrophils in the airways in chronic obstructive pulmonary disease (COPD) but the underlying mechanisms remain poorly understood. It is known that extracellular cytokine signaling via interleukin (IL)-17A contributes to neutrophil accumulation in the airways but nothing is known about the impact of tobacco smoking on extracellular signaling via IL-17A. Here, we characterized the impact of tobacco smoking on extracellular cytokine signaling via IL-17A in the peripheral airways in long-term smokers with and without COPD and in occasional smokers before and after short-term exposure to tobacco smoke. We quantified concentrations of IL-17A protein in cell-free bronchoalveolar lavage (BAL) fluid samples (Immuno-quantitative PCR) and cytotoxic T-cells (immunoreactivity for CD8⁺ and CD3⁺) in bronchial biopsies. Matrix metalloproteinase-8 and human beta defensin 2 proteins were also quantified (enzyme-linked immunosorbent assay) in the BAL samples. The concentrations of IL-17A in BAL fluid were higher in long-term smokers without COPD compared with nonsmoking healthy controls, whereas those with COPD did not differ significantly from either of the other groups. Short-term exposure to tobacco smoke did not induce sustained alterations in these concentrations in occasional smokers. Long-term smokers displayed higher concentrations of IL-17A than did occasional smokers. Moreover, these concentrations correlated with CD8⁺ and CD3⁺ cells in biopsies among long-term smokers with COPD. In healthy nonsmokers, BAL concentrations of matrix metalloproteinase-8 and IL-17A correlated, whereas this was not the case in the pooled group of long-term smokers with and without COPD. In contrast, BAL concentrations of human beta defensin 2 and IL-17A correlated in all study groups. This study implies that long-term but not short-term exposure to tobacco smoke increases extracellular cytokine signaling via IL-17A in the peripheral airways. In the smokers with COPD, this signaling may involve cytotoxic T-cells. Long-term exposure to tobacco smoke leads to a disturbed association of extracellular IL-17A signaling and matrix metalloproteinase-8, of potential importance for the coordination of antibacterial activity.

Extracellular cadmium in the bronchoalveolar space of long-term tobacco smokers with and without COPD and its association with inflammation

Tobacco contains cadmium, and this metal has been attributed a causative role in pulmonary emphysema among smokers, although extracellular cadmium has not to date been quantified in the bronchoalveolar space of tobacco smokers with or without COPD. We determined whether cadmium is enhanced in the bronchoalveolar space of long-term tobacco smokers with or without COPD in vivo, its association with inflammation, and its effect on chemokine release in macrophage-like cells in vitro. Bronchoalveolar lavage (BAL), sputum, and blood samples were collected from current, long-term smokers with and without COPD and from healthy nonsmokers. Cadmium concentrations were determined in cell-free BAL fluid using inductively coupled plasma mass spectrometry. Blood monocyte-derived macrophages were exposed to cadmium chloride in vitro. Depending upon the type of sample, molecular markers of inflammation were quantified either as protein (enzyme-linked immunosorbent assay) or as mRNA (real-time polymerase chain reaction). Cadmium concentrations were markedly increased in cell-free BAL fluid of smokers compared to that of nonsmokers (n=19–29; P<0.001), irrespective of COPD. In these smokers, the measured cadmium displayed positive correlations with macrophage TNF-α mRNA in BAL, neutrophil and CD8⁺ cell concentrations in blood, and finally with IL-6, IL-8, and MMP-9 protein in sputum (n=10–20; P<0.05). The cadmium chloride exposure caused a concentration-dependent increase in extracellular IL-8 protein in monocyte-derived macrophages in vitro. In conclusion, extracellular cadmium is enhanced in the bronchoalveolar space of long-term smokers and displays pro-inflammatory features. Its pathogenic role in tobacco-induced disease deserves further evaluation.

The phenotype of concurrent chronic bronchitis and frequent exacerbations in patients with severe COPD attending Swedish secondary care units

BACKGROUND

Chronic bronchitis and previous exacerbations are both well-known risk factors for new exacerbations, impaired health-related quality of life, and increased mortality in COPD. The aim of the study was to characterize the phenotype of concurrent chronic bronchitis and frequent exacerbation in severe COPD.

METHODS

Information on patient characteristics, comorbidity, and exacerbations from the previous year (total number and number requiring hospitalization) was collected from 373 patients with stage III and IV COPD attending 27 secondary care respiratory units in Sweden. Logistic regression used chronic bronchitis and frequent exacerbations (≥2 exacerbations or ≥1 hospitalized exacerbations in the previous year) as response variables. Stratification and interaction analyses examined effect modification by sex.

RESULTS

Chronic bronchitis was associated with current smoking (adjusted odds ratio [OR] [95% CI], 2.75 [1.54-4.91]; P=0.001), frequent exacerbations (OR [95% CI], 1.93 [1.24-3.01]; P=0.004), and musculoskeletal symptoms (OR [95% CI], 1.74 [1.05-2.86]; P=0.031), while frequent exacerbations were associated with lung function (forced expiratory volume in 1 second as a percentage of predicted value [FEV1% pred]) (OR [95% CI] 0.96 [0.94-0.98]; P=0.001) and chronic bronchitis (OR [95% CI] 1.73 [1.11-2.68]; P=0.015). The phenotype with both chronic bronchitis and frequent exacerbations was associated with FEV1% pred (OR [95% CI] 0.95 [0.92-0.98]; P=0.002) and musculoskeletal symptoms (OR [95% CI] 2.55 [1.31-4.99]; P=0.006). The association of smoking with the phenotype of chronic bronchitis and exacerbations was stronger in women than in men (interaction, P=0.040).

CONCLUSION

Musculoskeletal symptoms and low lung function are associated with the phenotype of combined chronic bronchitis and frequent exacerbations in severe COPD. In women, current smoking is of specific importance for this phenotype. This should be considered in clinical COPD care.

Interleukin-26: An Emerging Player in Host Defense and Inflammation

The production of interleukin (IL)-26 was initially attributed to T cells, and in particular to Th17 cells. However, more recent findings indicate IL-26 production in natural killer (NK) cells, macrophages and fibroblast-like cells as well. It is known that IL-26 binds to the IL-20R1/IL-10R2 receptor complex on certain target cells, where it causes specific intracellular signaling and the secretion of IL-1β, IL-8 and TNF-α. In line with this type of proinflammatory role, IL-26 also increases chemotaxis of human neutrophils. Interestingly, high levels of IL-26 are present even in normal human airways, and endotoxin exposure further enhances these levels; this indicates involvement in antibacterial host defense. Studies on acute inflammatory disorders are few but there are studies showing the involvement of IL-26 in rheumatoid arthritis and inflammatory bowel disease. In conclusion, IL-26 is emerging as a potentially important player in host defense and may also be a pathogenic factor in the chronic inflammatory disorders of humans.

Systemic signs of neutrophil mobilization during clinically stable periods and during exacerbations in smokers with obstructive pulmonary disease

BACKGROUND

It is still unclear whether signs of neutrophil mobilization in the blood of patients with chronic obstructive pulmonary disease represent true systemic events and how these relate to bacterial colonization in the airways. In this study, we evaluated these issues during clinically stable periods and during exacerbations in smokers with obstructive pulmonary disease and chronic bronchitis (OPD-CB).

METHODS

Over a period of 60 weeks for each subject, blood samples were repeatedly collected from 60 smokers with OPD-CB during clinically stable periods, as well as during and after exacerbations. Myeloperoxidase (MPO) and neutrophil elastase (NE) protein and mRNA, growth of bacteria in sputum, and clinical parameters were analyzed. Ten asymptomatic smokers and ten never-smokers were included as controls.

RESULTS

We found that, during clinically stable periods, neutrophil and NE protein concentrations were increased in smokers with OPD-CB and in the asymptomatic smokers when compared with never-smokers. During exacerbations, neutrophil and MPO protein concentrations were further increased in smokers with OPD-CB, without a detectable increase in the corresponding mRNA during exacerbations. However, MPO and NE protein and mRNA displayed positive correlations. During exacerbations, only increased neutrophil concentrations were associated with growth of bacteria in sputum. Among patients with low transcutaneous oxygen saturation during exacerbations, PaO2 (partial oxygen pressure) correlated with concentrations of MPO and NE protein and neutrophils in a negative manner.

CONCLUSION

There are signs of systemic neutrophil mobilization during clinically stable periods and even more so during exacerbations in chronic obstructive pulmonary disease. In this condition, MPO and NE may share a cellular origin, but its location remains uncertain. Factors other than local bacteria, including hypoxemia, may be important for driving systemic signs of neutrophil mobilization.