Airway Bacteria Quantification Using Polymerase Chain Reaction Combined with Neutrophil and Eosinophil Counts Identifies Distinct COPD Endotypes

The relevance of eosinophils in chronic obstructive pulmonary disease: inflammation, microbiome, and clinical outcomes

Chronic obstructive pulmonary disease is caused by the inhalation of noxious particles such as cigarette smoke. The pathophysiological features include airway inflammation, alveolar destruction, and poorly reversible airflow obstruction. A subgroup of patients with chronic obstructive pulmonary disease has higher blood eosinophil counts, associated with an increased response to inhaled corticosteroids and increased biomarkers of pulmonary type 2 inflammation. Emerging evidence shows that patients with chronic obstructive pulmonary disease with increased pulmonary eosinophil counts have an altered airway microbiome. Higher blood eosinophil counts are also associated with increased lung function decline, implicating type 2 inflammation in progressive pathophysiology in chronic obstructive pulmonary disease. We provide a narrative review of the role of eosinophils and type 2 inflammation in the pathophysiology of chronic obstructive pulmonary disease, encompassing the lung microbiome, pharmacological targeting of type 2 pathways in chronic obstructive pulmonary disease, and the clinical use of blood eosinophil count as a chronic obstructive pulmonary disease biomarker.

New methods to detect bacterial or viral infections in patients with chronic obstructive pulmonary disease

INTRODUCTION

Patients with chronic obstructive pulmonary disease (COPD) are frequently colonized and infected by respiratory pathogens. Identifying these infectious etiologies is critical for understanding the microbial dynamics of COPD and for the appropriate use of antimicrobials during exacerbations.

AREAS COVERED

Traditional methods, such as bacterial and viral cultures, have been standard in diagnosing respiratory infections. However, these methods have significant limitations, including lack of sensitivity and prolonged turnaround time. Modern molecular approaches offer rapid, sensitive, and specific detection, though they also come with their own challenges. This review explores and evaluates the clinical utility of the latest advancements in detecting bacterial and viral respiratory infections in COPD, encompassing molecular techniques, biomarkers, and emerging technologies.

EXPERT OPINION

In the evolving landscape of COPD management, integrating molecular diagnostics and emerging technologies holds great promise. The enhanced sensitivity of molecular techniques has significantly advanced our understanding of the role of microbes in COPD. However, many of these technologies have primarily been developed for pneumonia diagnosis or research applications, and their clinical utility in managing COPD requires further evaluation.

How inhaled corticosteroids target inflammation in COPD

Inhaled corticosteroids (ICS) are the most commonly used anti-inflammatory drugs for the treatment of COPD. COPD has been previously described as a "corticosteroid-resistant" condition, but current clinical trial evidence shows that selected COPD patients, namely those with increased exacerbation risk plus higher blood eosinophil count (BEC), can benefit from ICS treatment. This review describes the components of inflammation modulated by ICS in COPD and the reasons for the variation in response to ICS between individuals. There are corticosteroid-insensitive inflammatory pathways in COPD, such as bacteria-induced macrophage interleukin-8 production and resultant neutrophil recruitment, but also corticosteroid-sensitive pathways including the reduction of type 2 markers and mast cell numbers. The review also describes the mechanisms whereby ICS can skew the lung microbiome, with reduced diversity and increased relative abundance, towards an excess of proteobacteria. BEC is a biomarker used to enable the selective use of ICS in COPD, but the clinical outcome in an individual is decided by a complex interacting network involving the microbiome and airway inflammation.

Early diagnostic BioMARKers in exacerbations of chronic obstructive pulmonary disease: protocol of the exploratory, prospective, longitudinal, single-centre, observational MARKED study

INTRODUCTION

Acute exacerbations of chronic obstructive pulmonary disease (AECOPD) play a pivotal role in the burden and progressive course of chronic obstructive pulmonary disease (COPD). As such, disease management is predominantly based on the prevention of these episodes of acute worsening of respiratory symptoms. However, to date, personalised prediction and early and accurate diagnosis of AECOPD remain unsuccessful. Therefore, the current study was designed to explore which frequently measured biomarkers can predict an AECOPD and/or respiratory infection in patients with COPD. Moreover, the study aims to increase our understanding of the heterogeneity of AECOPD as well as the role of microbial composition and hostmicrobiome interactions to elucidate new disease biology in COPD.

METHODS AND ANALYSIS

The 'Early diagnostic BioMARKers in Exacerbations of COPD' study is an exploratory, prospective, longitudinal, single-centre, observational study with 8-week follow-up enrolling up to 150 patients with COPD admitted to inpatient pulmonary rehabilitation at Ciro (Horn, the Netherlands). Respiratory symptoms, vitals, spirometry and nasopharyngeal, venous blood, spontaneous sputum and stool samples will be frequently collected for exploratory biomarker analysis, longitudinal characterisation of AECOPD (ie, clinical, functional and microbial) and to identify host-microbiome interactions. Genomic sequencing will be performed to identify mutations associated with increased risk of AECOPD and microbial infections. Predictors of time-to-first AECOPD will be modelled using Cox proportional hazards' regression. Multiomic analyses will provide a novel integration tool to generate predictive models and testable hypotheses about disease causation and predictors of disease progression.

ETHICS AND DISSEMINATION

This protocol was approved by the Medical Research Ethics Committees United (MEC-U), Nieuwegein, the Netherlands (NL71364.100.19).

TRIAL REGISTRATION NUMBER

NCT05315674.

Benefits of Budesonide/Glycopyrronium/Formoterol Fumarate Dihydrate on COPD Exacerbations, Lung Function, Symptoms, and Quality of Life Across Blood Eosinophil Ranges: A Post-Hoc Analysis of Data from ETHOS

Purpose

Blood eosinophil (EOS) count can guide treatment decisions for chronic obstructive pulmonary disease (COPD). In the 52-week ETHOS study (NCT02465567), budesonide/glycopyrronium/formoterol fumarate dihydrate (BGF) triple therapy at two inhaled corticosteroid doses reduced moderate/severe exacerbation rates and improved lung function, symptoms, and disease-related quality of life (QoL) versus dual therapy with glycopyrronium/formoterol fumarate dihydrate (GFF) or budesonide/formoterol fumarate dihydrate (BFF) in patients with moderate-to-very severe COPD. This subgroup analysis evaluated treatment benefits in ETHOS by baseline EOS count.

Methods

Patients (40-80 years) with a COPD history were randomly assigned 1:1:1:1 to receive BGF 320/14.4/10 µg, BGF 160/14.4/10 µg, GFF 14.4/10 µg, or BFF 320/10 µg via a metered-dose inhaler. This post-hoc analysis assessed endpoints by baseline EOS count using Global Initiative for Obstructive Lung Disease thresholds (<100, ≥100, ≥100-<300, ≥300 cells/mm³), and investigated continuous relationships between treatment effects and EOS count on exacerbations, symptoms, disease-related QoL, lung function, and safety.

Results

In the modified intention-to-treat population (n=8509), 82.6% had EOS counts ≥100 cells/mm³. BGF 320 reduced moderate/severe exacerbation rates versus GFF in the ≥100, ≥100-<300, and ≥300 subgroups; treatment differences increased with EOS count. BGF 320 improved rescue medication use and lung-function outcomes across all subgroups, and St George's Respiratory Questionnaire total score, Transition Dyspnea Index focal score, and Exacerbations of Chronic Pulmonary Disease Tool total score in all except the <100 subgroup versus GFF. Benefits of BGF 320 versus BFF were generally consistent across subgroups. Safety data were comparable across subgroups.

Conclusion

Benefits of BGF versus GFF were observed across EOS counts, particularly at ≥100 cells/mm³; versus BFF, benefits were largely independent of EOS. These findings confirm that benefits of ICS-containing triple therapy are not restricted to EOS counts ≥300 cells/mm³, supporting recommendations to consider triple therapy in patients with an exacerbation history and EOS counts ≥100 cells/mm³.

Identification of COPD Inflammatory Endotypes Using Repeated Sputum Eosinophil Counts

Higher blood and sputum eosinophil counts are associated with a greater response to corticosteroids in COPD. Low blood eosinophil counts exhibit greater stability over time whereas higher counts demonstrate more variability. Stability of airway eosinophil levels is less well understood. We have studied the stability of sputum eosinophil counts. Differential cell count data for COPD patients (n = 100) were analysed. Subjects with two sputum eosinophil counts, 6 months apart, were included in the analysis. Patients were stratified based on baseline sputum eosinophil count into ‘low’, ‘intermediate’ and ‘high’ groups: eosinophilLOW (<1%), eosinophilINT (1−3%) and eosinophilHIGH (≥3%). Sputum eosinophil counts showed good stability (rho = 0.61, p < 0.0001, ICC of 0.77), with 67.4% of eosinophilLOW patients remaining in the same category on repeat sampling. Bland−Altman analysis of the whole cohort (median difference between measurements = 0.00%, 90th percentile = −1.4 and 4.7%) showed greater variation at higher counts. This was confirmed by the wider 90th centiles in the eosinophilINT (−1.50 to 5.65) and eosinophilHIGH groups (−5.33 to 9.80) compared to the eosinophilLOW group (−0.40 to 1.40). The repeatability of sputum eosinophil counts was related to the baseline eosinophil count; sputum eosinophilLOW COPD patients were relatively stable over time, while the eosinophilHIGH group showed greater variability. These results can facilitate the identification of COPD endotypes with differential responses to treatment.

Gallium protoporphyrin as an antimicrobial for non-typeable Haemophilus influenzae in COPD patients

AIMS

Colonisation with non-typeable Haemophilus influenzae (NTHi) is common in COPD. Iron is required by bacteria for nutrition. Gallium is imported into bacteria using iron import proteins. Gallium cannot fulfill key metabolic functions, causing bactericidal effects. We tested the efficacy of gallium compounds as antimicrobials against NTHi in hemin rich conditions, and their ability to reduce NTHi induced pro-inflammatory responses in macrophages.

MAIN METHODS

NTHi was cultured with the free iron analogue gallium nitrate (GaN) and heme iron analogue gallium protoporphyrin (GaPP) (0.5-4 μM; 24 h). Growth of NTHi reference strain (NCTC 12699) and 6 clinical isolates from COPD patients (including antibiotic resistant isolates) was assessed by optical density, and viability by Miles Misra. Monocyte derived macrophages (MDMs) were treated with GaPP before/after NTHi exposure. Viable intracellular NTHi was assessed by gentamicin protection assay. GaN or GaPP was added to NTHi cultures prior to culture with MDMs. Cytokine gene expression (qPCR) and protein secretion (ELISA) were measured.

KEY FINDINGS

NTHi growth and viability were reduced by GaPP but not GaN. GaPP inhibited growth of COPD isolates (4 μM: 87 % reduction). GaPP reduced intracellular viability of NTHi in macrophage infection models. MDM cytokine gene expression and protein secretion (TNF-α, IL-6 and CXCL8) in response to NTHi was reduced (82, 66 and 86 % for gene expression) when cultured with GaPP 4 μM.

SIGNIFICANCE

GaPP is an effective antimicrobial for NTHi while GaN showed no effect on growth or viability. Culture of NTHi with GaPP also reduced the pro-inflammatory cytokine response in MDMs.

Relationships between Airway Remodeling and Clinical Characteristics in COPD Patients

Background: Airway remodeling is a cardinal feature of chronic obstructive pulmonary disease (COPD) pathology. However, inconsistent findings have been reported regarding the nature of proximal airway remodeling in COPD. This is likely due to the heterogeneity of COPD. This study investigated the histopathological features of airway remodeling in bronchial biopsies of COPD patients compared to smoking controls (S). We tested the hypothesis that histopathological features in bronchial biopsies relate to clinical characteristics in COPD patients, focusing on smoking status, symptom burden, lung function, exacerbation risk and inhaled corticosteroid (ICS) use. Methods: We recruited 24 COPD patients and 10 S. We focused on reticular basement membrane thickness (RBM), surface immunoglobulin A (IgA) expression, goblet cell numbers (periodic acid-Schiff [PAS]+), sub-mucosal remodeling markers including collagen 4, 6 and laminin expression, and inflammatory cell counts (CD45+). Results: RBM thickness was increased in frequent exacerbators, IgA expression was reduced in COPD patients with worse lung function, and goblet cell numbers were increased in COPD patients compared to S but with no difference between the COPD subgroups. Collagen 4 expression was associated with higher symptom burden and worse quality of life. Sub-mucosal inflammatory cell counts were increased in COPD non-inhaled corticosteroid (ICS) users compared to ICS users and S. Conclusion: We observed relationships between the histopathological features of airway remodeling and clinical characteristics in COPD patients. Our data highlight the influence of clinical heterogeneity on diverse patterns of airway remodeling in COPD patients.

Validation of Sputum Biomarker Immunoassays and Cytokine Expression Profiles in COPD

Immunoassays are commonly used to assess airway inflammation in sputum samples from chronic obstructive pulmonary disease (COPD) patients. However, assay performance and validation in this complex matrix is inconsistently reported. The aim of this study was to assess the suitability of various immunoassays for use with sputum samples, followed by use of validated immunoassays to evaluate biomarker levels in COPD patients. Assays were assessed for recombinant reference standard suitability, optimal sample dilution, standard recovery in the biological matrix and reproducibility. Validated assays were used to assess sputum supernatants in Cohort A (n = 30 COPD, n = 10 smokers, n = 10 healthy) and Cohort B (n = 81 COPD, n = 15 smokers, n = 26 healthy). Paired baseline and exacerbation samples from 14 COPD patients were assessed in cohort A, and associations with sputum cell counts and bacterial colonisation investigated in cohort B. 25/32 assays passed validation; the primary reason for validation failure was recombinant reference standard suitability and sample dilution effects. Interleukin (IL-)6 and IL-8 were significantly increased in COPD patients compared to healthy subjects and smokers for both cohorts. Tumour necrosis factor (TNF)α and IL-1β were higher in COPD compared to smokers using one immunoassay but not another, partly explained by different absolute recovery rates. IL-1β, IL-2, IL-4, IL-8, IL-17A, Granulocyte colony stimulating factor (G-CSF), Interferon (IFN-)γ, Interferon gamma induced protein (IP-)10, Macrophage inflammatory protein (MIP)-1α, MIP-1β and TNF-α levels correlated with sputum neutrophil percentage in COPD patients. IL-1β, IL-4, IL-8, G-CSF and IFN-γ levels were associated with Haemophilus influenzae colonisation in COPD patients. Current smokers had lower levels of IL-1β, IL-4, IL-8, G-CSF, IFN-γ, IP-10, Monocyte chemoattractant protein (MCP)-1, MIP-1α, MIP-1β and TNF-α. Validated immunoassays applied to sputum supernatants demonstrated differences between COPD patients and controls, the effects of current smoking and associations between Haemophilus influenzae colonisation and higher levels of selected cytokines. Immunoassay validation enabled inflammatory mediators associated with different COPD characteristics to be determined.

Blood Eosinophils and Chronic Obstructive Pulmonary Disease: A GOLD Science Committee 2022 Review

COPD is a heterogeneous condition. Some patients benefit from treatment with inhaled corticosteroids (ICS) but this requires a precision medicine approach, based on clinical characteristics (phenotyping) and biological information (endotyping) in order to select patients most likely to benefit. The GOLD 2019 report recommended using exacerbation history combined with blood eosinophil counts (BEC) to identify such patients. Importantly, the relationship between BEC and ICS effects is continuous; no / small effects are observed at lower BEC, with increasing effects at higher BEC. The GOLD 2022 report has added additional evidence and recommendations concerning the use of BEC in COPD in clinical practice. Notably, associations have been demonstrated in COPD patients between higher BEC and increased levels of type-2 inflammation in the lungs. These differences in type-2 inflammation can explain the differential ICS response according to BEC. Additionally, lower BEC are associated with greater presence of proteobacteria, notably haemophilus, and increased bacterial infections and pneumonia risk. These observations support management strategies that use BEC to help identify subgroups with increased ICS response (higher BEC) or increased risk of bacterial infection (lower BEC). Recent studies in younger individuals without COPD have also shown that higher BEC are associated with increased risk of FEV1 decline and the development of COPD. Here we discuss and summarise the GOLD 2022 recommendations concerning the use of BEC as a biomarker that can facilitate a personalised management approach in COPD.

Vaccination and modern management of chronic obstructive pulmonary disease - a narrative review

INTRODUCTION

Chronic obstructive pulmonary disease (COPD) carries a tremendous societal and individual burden, posing significant challenges for public health systems worldwide due to its high morbidity and mortality. Due to aging and multimorbidity but also in the wake of important progress in deciphering the heterogeneous disease endotypes, an individualized approach to the prevention and management of COPD is necessary.

AREAS COVERED

This article tackles relevant immunization strategies that are available or still under development with a focus on the latest evidence but also controversies around different regional immunization approaches. Further, we present the crossover between chronic lung inflammation and lung microbiome disturbance as well as its role in delineating COPD endotypes. Moreover, the article attempts to underline endotype-specific treatment approaches. Lastly, we highlight non-pharmacologic prevention and management programs in view of the challenges and opportunities of the COVID-19 era.

EXPERT OPINION

Despite the remaining challenges, personalized medicine has the potential to offer tailored approaches to prevention and therapy and promises to improve the care of patients living with COPD.

Differential responses of COPD macrophages to respiratory bacterial pathogens

COPD patients have increased susceptibility to airway bacterial colonisation. Haemophilus influenzae, Moraxella catarrhalis and Streptococcus pneumoniae are three of the most common respiratory bacterial species in COPD. H. influenzae colonisation, but not other bacteria, in COPD patients is associated with higher sputum neutrophil counts. Alveolar macrophages are key in clearance of bacteria as well as releasing mediators to recruit and activate other immune cells in response to infection. The aim was to characterise differences in COPD macrophage responses to H. influenzae, M. catarrhalisand S. pneumoniae, focusing on release of inflammatory and chemotactic mediators, and apoptosis regulation.

 Lung macrophages and monocyte-derived macrophages from COPD patients and control subjects were exposed to H. influenzae, M. catarrhalisor S. pneumoniae. Cytokine secretion (tumour necrosis factor-α, interleukin (IL)-6, CXCL8, CCL5 and IL-1β) were measured by ELISA and quantitative reverse transcriptase PCR (RT-qPCR), and apoptosis genes MCL-1, BCL-2, BAX and BAK1 by RT-qPCR. Apoptosis and reactive oxygen species (ROS) release were also measured.

 Macrophages responded differentially to the bacterial species, with increased, prolonged production of the neutrophil chemoattractant CXCL8 in response to H. influenzae and M. catarrhalis but not S. pneumoniae. S. pneumoniae initiated macrophage apoptosis and ROS release, H. influenzae and M. catarrhalis did not and increased anti-apoptosis gene expression (BCL-2 5.5-fold and MCL-1 2.4-fold, respectively).

 Differential cytokine responses of macrophages to these bacterial species can explain neutrophilic airway inflammation associated with H. influenzae, but not S. pneumoniae in COPD. Furthermore, delayed macrophage apoptosis is a potential mechanism contributing to inability to clear H. influenzae.

Differential cytokine responses of macrophages to Haemophilus influenzae, Moraxella catarrhalis and Streptococcus pneumoniae can explain neutrophilic airway inflammation associated with H. influenzae but not S. pneumoniae in COPDhttps://bit.ly/3950HVZ

A sputum 6-gene signature predicts airway inflammation endotypes and exacerbation frequency in chronic obstructive pulmonary disease

Aim: To validate a sputum 6-gene signature (6GS), comprising of CLC, CPA, DNASE1L3, IL-1B, ALPL and CXCR2, for identifying different endotypes in chronic obstructive pulmonary disease. Methodology & results: Sputum cell CLC, CPA3 and DNASE1L3 gene expression correlated with eosinophil percentage, while IL-1B, ALPL and CXCR2 correlated with neutrophil percentage. Hierarchical cluster analyses of IL-1B, ALPL and CXCR2, and CLC, CPA3 and DNASE1L3, identified patient groups that differed in their sputum neutrophil and eosinophil levels, respectively. Multiple logistic regressions demonstrated that the 6GS could distinguish between eosinophil^High and eosinophil^Low patients, as well as neutrophil^High and neutrophil^Low, and could also predict exacerbation history. Conclusion: The 6GS may have applications in clinical practice or for stratifying patients for clinical trials.