Methods for the assessment of endobronchial biopsies in clinical research: application to studies of pathogenesis and the effects of treatment

Eosinophils-from cradle to grave: An EAACI task force paper on new molecular insights and clinical functions of eosinophils and the clinical effects of targeted eosinophil depletion

Over the past years, eosinophils have become a focus of scientific interest, especially in the context of their recently uncovered functions (e.g. antiviral, anti-inflammatory, regulatory). These versatile cells display both beneficial and detrimental activities under various physiological and pathological conditions. Eosinophils are involved in the pathogenesis of many diseases which can be classified into primary (clonal) and secondary (reactive) disorders and idiopathic (hyper)eosinophilic syndromes. Depending on the biological specimen, the eosinophil count in different body compartments may serve as a biomarker reflecting the underlying pathophysiology and/or activity of distinct diseases and as a therapy-driving (predictive) and monitoring tool. Personalized selection of an appropriate therapeutic strategy directly or indirectly targeting the increased number and/or activity of eosinophils should be based on the understanding of eosinophil homeostasis including their interactions with other immune and non-immune cells within different body compartments. Hence, restoring as well as maintaining homeostasis within an individual's eosinophil pool is a goal of both specific and non-specific eosinophil-targeting therapies. Despite the overall favourable safety profile of the currently available anti-eosinophil biologics, the effect of eosinophil depletion should be monitored from the perspective of possible unwanted consequences.

Advanced models for respiratory disease and drug studies

The global burden of respiratory diseases is enormous, with many millions of people suffering and dying prematurely every year. The global COVID-19 pandemic witnessed recently, along with increased air pollution and wildfire events, increases the urgency of identifying the most effective therapeutic measures to combat these diseases even further. Despite increasing expenditure and extensive collaborative efforts to identify and develop the most effective and safe treatments, the failure rates of drugs evaluated in human clinical trials are high. To reverse these trends and minimize the cost of drug development, ineffective drug candidates must be eliminated as early as possible by employing new, efficient, and accurate preclinical screening approaches. Animal models have been the mainstay of pulmonary research as they recapitulate the complex physiological processes, Multiorgan interplay, disease phenotypes of disease, and the pharmacokinetic behavior of drugs. Recently, the use of advanced culture technologies such as organoids and lung-on-a-chip models has gained increasing attention because of their potential to reproduce human diseased states and physiology, with clinically relevant responses to drugs and toxins. This review provides an overview of different animal models for studying respiratory diseases and evaluating drugs. We also highlight recent progress in cell culture technologies to advance integrated models and discuss current challenges and present future perspectives.

Inhibition of Macrophage-Specific CHIT1 as an Approach to Treat Airway Remodeling in Severe Asthma

Chitotriosidase (CHIT1) is an enzyme produced by macrophages that regulates their differentiation and polarization. Lung macrophages have been implicated in asthma development; therefore, we asked whether pharmacological inhibition of macrophage-specific CHIT1 would have beneficial effects in asthma, as it has been shown previously in other lung disorders. CHIT1 expression was evaluated in the lung tissues of deceased individuals with severe, uncontrolled, steroid-naïve asthma. OATD-01, a chitinase inhibitor, was tested in a 7-week-long house dust mite (HDM) murine model of chronic asthma characterized by accumulation of CHIT1-expressing macrophages. CHIT1 is a dominant chitinase activated in fibrotic areas of the lungs of individuals with fatal asthma. OATD-01 given in a therapeutic treatment regimen inhibited both inflammatory and airway remodeling features of asthma in the HDM model. These changes were accompanied by a significant and dose-dependent decrease in chitinolytic activity in BAL fluid and plasma, confirming in vivo target engagement. Both IL-13 expression and TGFβ1 levels in BAL fluid were decreased and a significant reduction in subepithelial airway fibrosis and airway wall thickness was observed. These results suggest that pharmacological chitinase inhibition offers protection against the development of fibrotic airway remodeling in severe asthma.

Smoking induces shifts in cellular composition and transcriptome within the bronchial mucus barrier

BACKGROUND AND OBJECTIVE

Smoking disturbs the bronchial-mucus-barrier. This study assesses the cellular composition and gene expression shifts of the bronchial-mucus-barrier with smoking to understand the mechanism of mucosal damage by cigarette smoke exposure. We explore whether single-cell-RNA-sequencing (scRNA-seq) based cellular deconvolution (CD) can predict cell-type composition in RNA-seq data.

METHODS

RNA-seq data of bronchial biopsies from three cohorts were analysed using CD. The cohorts included 56 participants with chronic obstructive pulmonary disease [COPD] (38 smokers; 18 ex-smokers), 77 participants without COPD (40 never-smokers; 37 smokers) and 16 participants who stopped smoking for 1 year (11 COPD and 5 non-COPD-smokers). Differential gene expression was used to investigate gene expression shifts. The CD-derived goblet cell ratios were validated by correlating with staining-derived goblet cell ratios from the COPD cohort. Statistics were done in the R software (false discovery rate p-value < 0.05).

RESULTS

Both CD methods indicate a shift in bronchial-mucus-barrier cell composition towards goblet cells in COPD and non-COPD-smokers compared to ex- and never-smokers. It shows that the effect was reversible within a year of smoking cessation. A reduction of ciliated and basal cells was observed with current smoking, which resolved following smoking cessation. The expression of mucin and sodium channel (ENaC) genes, but not chloride channel genes, were altered in COPD and current smokers compared to never smokers or ex-smokers. The goblet cell-derived staining scores correlate with CD-derived goblet cell ratios.

CONCLUSION

Smoking alters bronchial-mucus-barrier cell composition, transcriptome and increases mucus production. This effect is partly reversible within a year of smoking cessation. CD methodology can predict goblet-cell percentages from RNA-seq.

Mucus from human bronchial epithelial cultures: rheology and adhesion across length scales

Mucus is a viscoelastic aqueous fluid that participates in the protective barrier of many mammals' epithelia. In the airways, together with cilia beating, mucus rheological properties are crucial for lung mucociliary function, and, when impaired, potentially participate in the onset and progression of chronic obstructive pulmonary disease (COPD). Samples of human mucus collected in vivo are inherently contaminated and are thus poorly characterized. Human bronchial epithelium (HBE) cultures, differentiated from primary cells at an air-liquid interface, are highly reliable models to assess non-contaminated mucus. In this paper, the viscoelastic properties of HBE mucus derived from healthy subjects, patients with COPD and from smokers are measured. Hallmarks of shear-thinning and elasticity are obtained at the macroscale, whereas at the microscale mucus appears as a heterogeneous medium showing an almost Newtonian behaviour in some extended regions and an elastic behaviour close to boundaries. In addition, we developed an original method to probe mucus adhesion at the microscopic scale using optical tweezers. The measured adhesion forces and the comparison with mucus-simulants rheology as well as mucus imaging collectively support a structure composed of a network of elastic adhesive filaments with a large mesh size, embedded in a very soft gel.

Expert opinion on NSCLC small specimen biomarker testing - Part 1: Tissue collection and management

Biomarker testing is crucial for treatment selection in advanced non-small cell lung cancer (NSCLC). However, the quantity of available tissue often presents a key constraint for patients with advanced disease, where minimally invasive tissue biopsy typically returns small samples. In Part 1 of this two-part series, we summarise evidence-based recommendations relating to small sample processing for patients with NSCLC. Generally, tissue biopsy techniques that deliver the greatest quantity and quality of tissue with the least risk to the patient should be selected. Rapid on-site evaluation can help to ensure sufficient sample quality and quantity. Sample processing should be managed according to biomarker testing requirements, because tissue fixation methodology influences downstream nucleic acid, protein and morphological analyses. Accordingly, 10% neutral buffered formalin is recommended as an appropriate fixative, and the duration of fixation is recommended not to exceed 24–48 h. Tissue sparing techniques, including the ‘one biopsy per block’ approach and small sample cutting protocols, can help preserve tissue. Cytological material (formalin-fixed paraffin-embedded [FFPE] cytology blocks and non-FFPE samples such as smears and touch preparations) can be an excellent source of nucleic acid, providing either primary or supplementary patient material to complete morphological and molecular diagnoses. Considerations on biomarker testing, reporting and quality assessment are discussed in Part 2.

The Microbiome in Bronchial Biopsies from Smokers and Ex-Smokers with Stable COPD - A Metatranscriptomic Approach

Current knowledge about the respiratory microbiome is mainly based on 16S ribosomal RNA gene sequencing. Newer sequencing approaches, such as metatranscriptomics, offer the technical ability to measure the viable microbiome response to environmental conditions such as smoking as well as to explore its functional role by investigating host-microbiome interactions. However, knowledge about its feasibility in respiratory microbiome research, especially in lung biopsies, is still very limited. RNA sequencing was performed in bronchial biopsies from clinically stable smokers (n = 5) and ex-smokers (n = 6) with COPD not using (inhaled) steroids. The Trinity assembler was used to assemble non-human reads in order to allow unbiased taxonomical and microbial transcriptional analyses. Subsequently, host-microbiome interactions were analyzed based on associations with host transcriptomic data. Ultra-low levels of microbial mass (0.009%) were identified in the RNA-seq data. Overall, no differences were identified in microbiome diversity or transcriptional profiles of microbial communities or individual microbes between COPD smokers and ex-smokers in the initial test dataset as well as a larger replication dataset. We identified an upregulated host gene set, related to the simultaneous presence of Bradyrhizobium, Roseomonas, Brevibacterium.spp., which were related to PERK-mediated unfolded protein response (UPR) and expression of the microRNA-155-5p. Our results show that metatranscriptomic profiling in bronchial biopsy samples from stable COPD patients yields ultra-low levels of microbial mass. Further, this study illustrates the potential of using transcriptional profiling of the host and microbiome to gain more insight into their interaction in the airways.

Airway smooth muscle remodelling in mild and moderate equine asthma

BACKGROUND

Airway smooth muscle remodelling in severe equine asthma includes both thickening of airway smooth muscle, resulting from hyperplasia and hypertrophy, and changes in contractility. However, airway smooth muscle changes have not been studied in milder forms of the disease.

OBJECTIVES

To investigate bronchial smooth muscle remodelling in horses with mild and moderate asthma (MEA).

STUDY DESIGN

Retrospective case-control study.

METHODS

The endobronchial biopsies from 18 horses with MEA referred to the Equine Hospital of the Université de Montréal and from seven healthy age-matched control horses were studied. The diagnosis was based on clinical signs and bronchoalveolar lavage fluid cytology. Airway smooth muscle cell proliferation was measured by quantifying the expression of the proliferating cell nuclear antigen (PCNA) using immunohistochemistry and histomorphometry. The expression of the (+)insert smooth muscle myosin heavy chain (SMMHC) isoform, an hypercontractile protein, was assessed by RT-qPCR.

RESULTS

Expression of the (+)insert SMMHC isoform in airway smooth muscle was approximately 1.5 times greater in horses with MEA compared with controls (P = .02, mean difference 0.01). Although there were no differences between groups in the proliferation of airway smooth muscle cells (P = .4) or myocyte density (P = .3, mean difference -0.6), the percentage of proliferating myocytes was correlated to pulmonary neutrophilia in horses with neutrophilic inflammation (P = .01, r = .80) and to the expression of the (+)insert SMMHC isoform in asthmatic horses (P = .03, r = .66).

MAIN LIMITATIONS

Small cohorts of horses were studied, and conclusions are limited to the central airways.

CONCLUSIONS

These results confirm the presence of bronchial smooth muscle remodelling in mild forms of equine asthma and pave the way for the development of biomarkers to measure asthma progression and response to therapy.

Role of Atypical Chemokines and Chemokine Receptors Pathways in the Pathogenesis of COPD

Chronic obstructive pulmonary disease (COPD) represents a heightened inflammatory response in the lung generally resulting from tobacco smoking-induced recruitment and activation of inflammatory cells and/or activation of lower airway structural cells. Several mediators can modulate activation and recruitment of these cells, particularly those belonging to the chemokines (conventional and atypical) family. There is emerging evidence for complex roles of atypical chemokines and their receptors (such as high mobility group box 1 (HMGB1), antimicrobial peptides, receptor for advanced glycosylation end products (RAGE) or toll-like receptors (TLRs)) in the pathogenesis of COPD, both in the stable disease and during exacerbations. Modulators of these pathways represent potential novel therapies for COPD and many are now in preclinical development. Inhibition of only a single atypical chemokine or receptor may not block inflammatory processes because there is redundancy in this network. However, there are many animal studies that encourage studies for modulating the atypical chemokine network in COPD. Thus, few pharmaceutical companies maintain a significant interest in developing agents that target these molecules as potential antiinflammatory drugs. Antibody-based (biological) and small molecule drug (SMD)-based therapies targeting atypical chemokines and/or their receptors are mostly at the preclinical stage and their progression to clinical trials is eagerly awaited. These agents will most likely enhance our knowledge about the role of atypical chemokines in COPD pathophysiology and thereby improve COPD management.

Immunologic Pathophysiology and Airway Remodeling Mechanism in Severe Asthma: Focused on IgE-Mediated Pathways

Despite the expansion of the understanding in asthma pathophysiology and the continual advances in disease management, a small subgroup of patients remains partially controlled or refractory to standard treatments. Upon the identification of immunoglobulin E (IgE) and other inflammatory mediators, investigations and developments of targeted agents have thrived. Omalizumab is a humanized monoclonal antibody that specifically targets the circulating IgE, which in turn impedes and reduces subsequent releases of the proinflammatory mediators. In the past decade, omalizumab has been proven to be efficacious and well-tolerated in the treatment of moderate-to-severe asthma in both trials and real-life studies, most notably in reducing exacerbation rates and corticosteroid use. While growing evidence has demonstrated that omalizumab may be potentially beneficial in treating other allergic diseases, its indication remains confined to treating severe allergic asthma and chronic idiopathic urticaria. Future efforts may be bestowed on determining the optimal length of omalizumab treatment, seeking biomarkers that could better predict treatment response and as well as extending its indications.

Airway Remodeling in Asthma

Asthma is an inflammatory disease of the airways that may result from exposure to allergens or other environmental irritants, resulting in bronchoconstriction, wheezing, and shortness of breath. The structural changes of the airways associated with asthma, broadly referred to as airway remodeling, is a pathological feature of chronic asthma that contributes to the clinical manifestations of the disease. Airway remodeling in asthma constitutes cellular and extracellular matrix changes in the large and small airways, epithelial cell apoptosis, airway smooth muscle cell proliferation, and fibroblast activation. These pathological changes in the airway are orchestrated by crosstalk of different cell types within the airway wall and submucosa. Environmental exposures to dust, chemicals, and cigarette smoke can initiate the cascade of pro-inflammatory responses that trigger airway remodeling through paracrine signaling and mechanostimulatory cues that drive airway remodeling. In this review, we explore three integrated and dynamic processes in airway remodeling: (1) initiation by epithelial cells; (2) amplification by immune cells; and (3) mesenchymal effector functions. Furthermore, we explore the role of inflammaging in the dysregulated and persistent inflammatory response that perpetuates airway remodeling in elderly asthmatics.

Multivariate Analysis Of The Diagnostic Yield Of Conventional Bronchoscopy In Peripheral Lung Adenocarcinoma

Background

The new subtypes of lung adenocarcinoma reflect local invasive growth, pulmonary alveoli, and intraluminal spreading, while the effective improvement of the diagnostic yield of bronchoscopy still remains unclear. This study aims to explore whether the subtypes of lung adenocarcinoma and other factors affect the diagnostic yield of bronchoscopy.

Methods

All patients were performed 64-row CT examination and bronchoscopy.

Results

The bronchus cutoff sign in 48 cases and the endoscopic diagnostic yield was 60.4%. The lumen of the lobes and segments was invaded in 59 cases, and the endoscopic diagnostic yield was 54.2%.The lymph node metastasis was detected in 46 cases, and the endoscopic diagnostic yield was 60.9%. In addition, 42 cases showed acinar type-predominant, and the endoscopic diagnostic yield was 28.6%. Eighteen cases showed solid type-predominant, and the endoscopic diagnostic yield was 33.3%. The micropapillary type-predominant was noted in 17 cases, with the endoscopic diagnostic yield as 94.1%. The papillary type-predominant was in 14 cases, and the endoscopic diagnostic yield was 42.9%. The lepidic type-predominant was seen in 13 cases, and the endoscopic diagnostic yield was 7.7%. The mean diameter of tumors with a positive endoscopic diagnostic yield was 4.34±2.65cm, and the mean diameter of tumors with a negative diagnostic yield was 2.83±1.47cm. Multivariate analysis showed that micropapillary lung adenocarcinoma affected the endoscopic diagnostic yield (OR=37.594, 95% CI: 4.074-346.94) .Tumor diameter affects endoscopic diagnostic yield (OR=1.39, 95% CI: 1.073-1.802), bronchus cutoff sign is easy to obtain endoscopic diagnostic yield (OR=4.86, 95% CI: 1.606-14.704), and lymph node metastasis affects the endoscopic diagnostic yield (OR=3.696, 95% CI: 1.255-10.883).

Conclusion

The micropapillary subtype lung adenocarcinoma has a certain influence on the diagnostic yield of bronchoscopy. When the lung adenocarcinoma has a large tumor diameter, bronchus cutoff sign and lymph node metastasis, it is easy to obtain a diagnostic yield of bronchoscopy.

The equine asthma model of airway remodeling: from a veterinary to a human perspective

Human asthma is a complex and heterogeneous disorder characterized by chronic inflammation, bronchospasm and airway remodeling. The latter is a major determinant of the structure-function relationship of the respiratory system and likely contributes to the progressive and accelerated decline in lung function observed in patients over time. Corticosteroids are the cornerstone of asthma treatment. While their action on inflammation and lung function is well characterized, their effect on remodeling remains largely unknown. An important hindrance to the study of airway remodeling as a major focus in asthma research is the lack of reliable non-invasive biomarkers. In consequence, the physiologic and clinical consequences of airway wall thickening and altered composition are not well understood. In this perspective, equine asthma provides a unique and ethical (non-terminal) preclinical model for hypothesis testing and generation. Severe equine asthma is a spontaneous disease affecting adult horses characterized by recurrent and reversible episodes of disease exacerbations. It is associated with bronchoalveolar neutrophilic inflammation, bronchospasm, and excessive mucus secretion. Severe equine asthma is also characterized by bronchial remodeling, which is only partially improved by prolonged period of disease remission induced by therapy or antigen avoidance strategies. This review will focus on the similarities and differences of airway remodeling in equine and human asthma, on the strengths and limitations of the equine model, and on the challenges the model has to face to keep up with human asthma research.

Safety and Tolerability of Comprehensive Research Bronchoscopy in Chronic Obstructive Pulmonary Disease. Results from the SPIROMICS Bronchoscopy Substudy

RATIONALE

There is an unmet need to investigate the lower airways in chronic obstructive pulmonary disease (COPD) to define pathogenesis and to identify potential markers to accelerate therapeutic development. Although bronchoscopy is well established to sample airways in various conditions, a comprehensive COPD research protocol has yet to be published.

OBJECTIVES

To evaluate the safety and tolerability of a comprehensive research bronchoscopy procedure suitable for multicenter trials and to identify factors associated with adverse events.

METHODS

We report the detailed methodology used to conduct the bronchoscopy used in SPIROMICS (the Subpopulations and Intermediate Outcome Measures in COPD Study). The protocol entailed collection of tongue scrapings and oral rinses as well as bronchoscopy with airway inspection, bronchoalveolar lavage (BAL), protected brushings, and endobronchial biopsies. Visual airway characteristics were graded on a scale of 0 (normal appearance) to 3 (severe abnormality) in four domains: erythema, edema, secretions, and friability. Adverse events were defined as events requiring intervention. Logistic regression modeling assessed associations between adverse event occurrence and key variables.

RESULTS

We enrolled 215 participants. They were 61 ± 9 years old, 71% were white, 53% were male, and post-bronchodilator forced expiratory volume in 1 second was 89 ± 19% predicted. Self-reported asthma was present in 22% of bronchoscopy participants. Oral samples were obtained in greater than or equal to 99% of participants. Airway characteristics were recorded in 99% and were most often characterized as free of edema (61.9%). Less than 50% reported secretions, friability, or erythema. BAL yielded 111 ± 57 ml (50%) of the 223 ± 65 ml of infusate, brushes were completed in 98%, and endobronchial biopsies were performed in 82% of procedures. Adverse events requiring intervention occurred in 14 (6.7%) of 208 bronchoscopies. In logistic regression models, female sex (risk ratio [RR], 1.10; 95% confidence interval [CI], 1.02-1.19), self-reported asthma (RR, 1.17; 95% CI, 1.02-1.34), bronchodilator reversibility (RR, 1.17; 95% CI, 1.04-1.32), COPD (RR, 1.10; 95% CI, 1.02-1.20), forced expiratory volume in 1 second (RR, 0.97; 95% CI, 0.95-0.99), and secretions (RR, 1.85; 1.08-3.16) or friability (RR, 1.64; 95% CI, 1.04-2.57) observed during bronchoscopy were associated with adverse events.

CONCLUSIONS

A research bronchoscopy procedure that includes oral sampling, BAL, endobronchial biopsy, and brushing can be safely performed. Airway characteristics during bronchoscopy, demographics, asthma or COPD, and lung function may convey increased risk for procedure-related events necessitating intervention.

Bronchoscopic mucosal cryobiopsies as a method for studying airway disease

BACKGROUND

Investigating disease mechanisms and treatment responses in obstructive airway diseases with invasive sampling are hampered by the small size and mechanical artefacts that conventional forceps biopsies suffer from. Endoscopic cryobiopsies are larger and more intact and are being increasingly used. However, the technique has not yet been explored for obtaining mucosa biopsies.

OBJECTIVE

To investigate differences in size and quality of endobronchial mucosal biopsies obtained with cryotechnique and forceps. Further, to check for eligibility of cryobiopsies to be evaluated with immunohistochemistry and in situ hybridization and to investigate tolerability and safety of the technique.

METHODS

Endobronchial mucosal biopsies were obtained with cryotechnique and forceps from patients with haemoptysis undergoing bronchoscopy and evaluated by quantitative morphometry, automated immunohistochemistry and in situ hybridization.

RESULTS

A total of 40 biopsies were obtained from 10 patients. Cross-sectional areas were threefold larger in cryobiopsies (median: 3.08 mm² (IQR: 1.79) vs 1.03 mm² (IQR: 1.10), P < 0.001). Stretches of intact epithelium were 8-fold longer (median: 4.61 mm (IQR: 4.50) vs 0.55 mm (IQR: 1.23), P = 0.001). Content of glands (median: 0.095 mm² (IQR: 0.30) vs 0.00 mm² (IQR: 0.01), P = 0.002) and airway smooth muscle (median: 0.25 mm² (IQR: 0.30) vs 0.060 mm² (IQR: 0.11), P = 0.02) was higher in the cryobiopsies compared with forceps biopsies. Further, the cryobiopsies had well-preserved protein antigens and mRNA. Mild to moderate bleeding was the only complication observed.

CONCLUSION AND CLINICAL RELEVANCE

By yielding significantly larger and more intact biopsies, the cryotechnique represents a valuable new research tool to explore the bronchi in airway disease. Ultimately with the potential to create better understanding of underlying disease mechanisms and improvement of treatments.

Using the Inflammacheck Device to Measure the Level of Exhaled Breath Condensate Hydrogen Peroxide in Patients With Asthma and Chronic Obstructive Pulmonary Disease (The EXHALE Pilot Study): Protocol for a Cross-Sectional Feasibility Study

BACKGROUND

Asthma and Chronic Obstructive Pulmonary Disease (COPD) are common conditions that affect over 5 million people in the United Kingdom. These groups of patients suffer significantly from breathlessness and recurrent exacerbations that can be difficult to diagnose and go untreated. A common feature of COPD and asthma is airway inflammation that increases before and during exacerbations. Current methods of assessing airway inflammation can be invasive, difficult to perform, and are often inaccurate. In contrast, measurement of exhaled breath condensate (EBC) hydrogen peroxide (H₂O₂) is performed during normal tidal breathing and is known to reflect the level of global inflammation in the airways. There is a need for novel tools to diagnose asthma and COPD earlier and to detect increased airway inflammation that precedes an exacerbation.

OBJECTIVE

The aim of this study was to explore the use of a new handheld device (called Inflammacheck) in measuring H₂O₂ levels in EBC. We will study whether it can measure EBC H₂O₂ levels consistently and whether it can be used to differentiate asthma and COPD from healthy controls.

METHODS

We will perform a cross-sectional, feasibility, pilot study of EBC H₂O₂ levels, as measured by Inflammacheck, and other markers of disease severity and symptom control in patients with asthma and COPD and volunteers with no history of lung disease. Participants will be asked to provide an exhaled breath sample for measurement of their EBC H₂O₂ using Inflammacheck. The result will be correlated with disease stage, spirometry, fractional exhaled nitric oxide (FeNO), and symptom control scores.

RESULTS

This study's recruitment is ongoing; it is anticipated that the results will be available in 2018.

CONCLUSIONS

The EXhaled Hydrogen peroxide As a marker of Lung diseasE (EXHALE) pilot study will provide an evaluation of a new method of measuring EBC H₂O₂. It will assess the device's consistency and ability to distinguish airway inflammation in asthma and COPD compared with healthy controls.

Associations in asthma between quantitative computed tomography and bronchial biopsy-derived airway remodelling

Airway remodelling in asthma remains poorly understood. This study aimed to determine the association of airway remodelling measured on bronchial biopsies with 1) lung function impairment and 2) thoracic quantitative computed tomography (QCT)-derived morphometry and densitometry measures of proximal airway remodelling and air trapping.Subjects were recruited from a single centre. Bronchial biopsy remodelling features that were the strongest predictors of lung function impairment and QCT-derived proximal airway morphometry and air trapping markers were determined by stepwise multiple regression. The best predictor of air trapping was validated in an independent replication group.Airway smooth muscle % was the only predictor of post-bronchodilator forced expiratory volume in 1 s (FEV₁) % pred, while both airway smooth muscle % and vascularity were predictors of FEV₁/forced vital capacity. Epithelial thickness and airway smooth muscle % were predictors of mean segmental bronchial luminal area (R²=0.12; p=0.02 and R²=0.12; p=0.015), whereas epithelial thickness was the only predictor of wall area % (R²=0.13; p=0.018). Vascularity was the only significant predictor of air trapping (R²=0.24; p=0.001), which was validated in the replication group (R²=0.19; p=0.031).In asthma, airway smooth muscle content and vascularity were both associated with airflow obstruction. QCT-derived proximal airway morphometry was most strongly associated with epithelial thickness and airway smooth muscle content, whereas air trapping was related to vascularity.

Activin A and follistatin in patients with asthma. Does severity make the difference?

BACKGROUND AND OBJECTIVE

Activin A is a pleiotropic cytokine holding a fundamental role in inflammation and tissue remodelling. Follistatin can modulate the bioactivity of activin. We aimed to measure activin A and follistatin in sputum supernatants and bronchoalveolar lavage (BAL) of asthmatic patients and to determine the possible associations with severity as well as with inflammatory and remodelling indices.

METHODS

A total of 58 asthmatic patients (33 with severe refractory asthma (SRA)) and 10 healthy controls underwent sputum induction for % cells, activin A, follistatin, eosinophilic cationic protein (ECP), transforming growth factor beta 1 (TGF-β1), IL-13 and IL-8 measurements. In 22 asthmatic patients, BAL and bronchial biopsies were also performed for the assessment of the above-mentioned variables, measurement of remodelling indices and immunostaining for different activin A receptors.

RESULTS

Sputum activin A (pg/mL) was higher in patients with SRA (median (interquartile ranges): 76 (33-185)) compared to mild-to-moderate asthma (44 (18-84); P = 0.005), whereas follistatin did not differ between the two groups. BAL activin A (pg/mL) was higher in patients with SRA compared to those with mild-to-moderate disease. A significant association was observed between activin A and TGF-β1, eosinophils in sputum and/or in BAL, while reticular basement membrane (RBM) thickness was significantly associated with BAL activin levels only. No difference in immunostaining for activin receptor type IB was observed between patients with SRA and those with mild-to-moderate asthma.

CONCLUSION

Sputum and BAL levels of activin A are higher in SRA. The association of activin A with TGF-β1, eosinophils and RBM thickness may indicate a role of this cytokine in the inflammatory and remodelling process in SRA.

DTI and Myelin Plasticity in Bipolar Disorder: Integrating Neuroimaging and Neuropathological Findings

Bipolar disorder (BD) is a major psychiatric illness with a chronic recurrent course, ranked among the worldwide leading disabling diseases. Its pathophysiology is still not completely understood and findings are still inconclusive, though a great interest on the topic has been constantly raised by magnetic resonance imaging, genetic and neuropathological studies. In recent years, diffusion tensor imaging (DTI) investigations have prompted interest in the key role of white matter (WM) abnormalities in BD. In this report, we summarize and comment recent findings from DTI studies in BD, reporting fractional anisotropy as putative measure of WM integrity, as well as recent data from neuropathological studies focusing on oligodendrocyte involvement in WM alterations in BD. DTI research indicates that BD is most commonly associated with a WM disruption within the fronto-limbic network, which may be accompanied by other WM changes spread throughout temporal and parietal regions. Neuropathological studies, mainly focused on the fronto-limbic network, have repeatedly shown a loss in cortical and subcortical oligodendrocyte cell count, although an increased subcortical oligodendrocyte density has been also documented suggesting a putative role in remyelination processes for oligodendrocytes in BD. According to our review, a greater integration between DTI and morphological findings is needed in order to elucidate processes affecting WM, either glial loss or myelin plasticity, on the basis of a more targeted research in BD.

Assessing particle and fiber toxicology in the respiratory system: the stereology toolbox

The inhalation of airborne particles can lead to pathological changes in the respiratory tract. For this reason, toxicology studies on effects of inhalable particles and fibers often include an assessment of histopathological alterations in the upper respiratory tract, the trachea and/or the lungs. Conventional pathological evaluations are usually performed by scoring histological lesions in order to obtain "quantitative" information and an estimation of the severity of the lesion. This approach not only comprises a potential subjective bias, depending on the examiner's judgment, but also conveys the risk that mild alterations escape the investigator's eye. The most accurate way of obtaining unbiased quantitative information about three-dimensional (3D) features of tissues, cells, or organelles from two-dimensional physical or optical sections is by means of stereology, the gold standard of image-based morphometry. Nevertheless, it can be challenging to express histopathological changes by morphometric parameters such as volume, surface, length or number only. In this review we therefore provide an overview on different histopathological lesions in the respiratory tract associated with particle and fiber toxicology and on how to apply stereological methods in order to correctly quantify and interpret histological lesions in the respiratory tract. The article further aims at pointing out common pitfalls in quantitative histopathology and at providing some suggestions on how respiratory toxicology can be improved by stereology. Thus, we hope that this article will stimulate scientists in particle and fiber toxicology research to implement stereological techniques in their studies, thereby promoting an unbiased 3D assessment of pathological lesions associated with particle exposure.

Asthma "of horses and men"--how can equine heaves help us better understand human asthma immunopathology and its functional consequences?

Animal models have been studied to unravel etiological, immunopathological, and genetic attributes leading to asthma. However, while experiments in which the disease is artificially induced have helped discovering biological and molecular pathways leading to allergic airway inflammation, their contribution to the understanding of the causality of the disease has been more limited. Horses naturally suffer from an asthma-like condition called "heaves" which presents sticking similarities with human asthma. It is characterized by reversible airway obstruction, airway neutrophilic inflammation, and a predominant Th2 immune response. This model allows one to investigate the role of neutrophils in asthma, which remains contentious, the regulation of chronic neutrophilic inflammation, and their possible implication in pulmonary allergic responses. Furthermore, the pulmonary remodeling features in heaves closely resemble those of human asthma, which makes this model unique to investigate the kinetics, reversibility, as well as the physiological consequences of tissue remodeling. In conclusion, heaves and asthma share common clinical presentation and also important immunological and tissue remodeling features. This makes heaves an ideal model for the discovery of novel pathways implicated in the asthmatic inflammation and associated tissue remodeling.

Technical and physiological determinants of airway smooth muscle mass in endobronchial biopsy samples of asthmatic horses

Morphometric analyses of endobronchial biopsies are commonly performed in asthma research but little is known about the technical and physiological parameters contributing to measurement variability. We investigated factors potentially affecting biopsy size, quality, and airway smooth muscle (ASM) content in heaves, an asthma-like disease of horses. Horses with heaves in clinical exacerbation (n = 6) or remission (n = 6) from the disease and six controls were studied using a crossover design. The effect of disease status, age, bronchodilation, biopsy forceps type, and carina size on total biopsy area (Atot), ASM area (AASM), ASM% (AASM/Atot), and histologic quality were assessed. Concordance among different measuring techniques was also assessed. Compared with other groups, horses with heaves in exacerbation yielded larger biopsies (P < 0.05). Better quality biopsies were obtained from carinae of small size compared with large ones (P = 0.02), and carina size and forceps type significantly affected the ASM content of the biopsy (interaction, P < 0.05). AASM increased with age only in heaves-affected horses (r = 0.9, P < 0.05), and ASM% was negatively correlated with pulmonary resistance at 5 Hz in heaves-affected horses (r = -0.74, P = 0.01), likely because of the increased thickness of the extracellular matrix layer in this group (P = 0.01). In conclusion, disease status, carina thickness, and the forceps used may significantly affect biopsy size, quality, and ASM content. Endobronchial biopsies are not appropriate samples for ASM quantification in heaves, and studies measuring ASM mass should not be compared when measuring techniques differ.

Advances in asthma drug discovery: evaluating the potential of nasal cell sampling and beyond

INTRODUCTION

Inhaled corticosteroid anti-inflammatory therapy is effective at controlling disease symptoms of asthma, but a subset of patients remains symptomatic despite optimal treatment, creating a clear unmet medical need. Moreover, none of the currently available drugs for asthma are really disease-modifying or curative. Although murine models of asthma, based on transgenic and knockout animals, may offer an integrated pathophysiological system for studying the characteristics of airway inflammation and hyperresponsiveness, these alterations are noteworthily different compared with those observed in asthmatic patients. Since a clear functional and inflammatory relationship between the nasal mucosa and bronchial tissue in patients suffering from asthma and allergic rhinitis has been recognized, using preclinical models based on human nasal cells sampling might support a prompt and effective anti-inflammatory drug discovery in asthma.

AREAS COVERED

The authors provide a review, which discusses the potential role of nasal cell sampling and its application in advanced drug discovery for asthma. The contents range from the similarities and differences between asthma and allergic rhinitis up to artificial airway models based on sophisticated human lung-on-a-chip devices.

EXPERT OPINION

Nasal cell sampling and processing have reached a great potential in asthma drug discovery. The authors believe that models of asthma, which are based on human nasal cells, can provide valuable indications of proof of pharmacological and potential therapeutic efficacy in both preclinical and early clinical settings.

Cell counting in human endobronchial biopsies--disagreement of 2D versus 3D morphometry

Question

Inflammatory cell numbers are important endpoints in clinical studies relying on endobronchial biopsies. Assumption-based bidimensional (2D) counting methods are widely used, although theoretically design-based stereologic three-dimensional (3D) methods alone offer an unbiased quantitative tool. We assessed the method agreement between 2D and 3D counting designs in practice when applied to identical samples in parallel.

Materials and Methods

Biopsies from segmental bronchi were collected from healthy non-smokers (n = 7) and smokers (n = 7), embedded and sectioned exhaustively. Systematic uniform random samples were immunohistochemically stained for macrophages (CD68) and T-lymphocytes (CD3), respectively. In identical fields of view, cell numbers per volume unit (N_V) were assessed using the physical disector (3D), and profiles per area unit (N_A) were counted (2D). For CD68⁺ cells, profiles with and without nucleus were separately recorded. In order to enable a direct comparison of the two methods, the zero-dimensional CD68⁺/CD3⁺-ratio was calculated for each approach. Method agreement was tested by Bland-Altmann analysis.

Results

In both groups, mean CD68⁺/CD3⁺ ratios for N_V and N_A were significantly different (non-smokers: 0.39 and 0.68, p<0.05; smokers: 0.49 and 1.68, p<0.05). When counting only nucleated CD68⁺ profiles, mean ratios obtained by 2D and 3D counting were similar, but the regression-based Bland-Altmann analysis indicated a bias of the 2D ratios proportional to their magnitude. This magnitude dependent deviation differed between the two groups.

Conclusions

2D counts of cell and nuclear profiles introduce a variable size-dependent bias throughout the measurement range. Because the deviation between the 3D and 2D data was different in the two groups, it precludes establishing a ‘universal conversion formula’.

Implementing lessons learned from previous bronchial biopsy trials in a new randomized controlled COPD biopsy trial with roflumilast

BACKGROUND

Chronic obstructive pulmonary disease (COPD) is a chronic inflammatory disease mediated by an array of inflammatory cells and mediators, but above all, CD8+ T-lymphocytes, macrophages and neutrophils are important players in disease pathogenesis. Roflumilast, a first-in-class, potent and selective phosphodiesterase 4 (PDE4) inhibitor, reduces the rate of exacerbations in patients with a high risk of future exacerbations and has been shown to reduce inflammatory cells and mediators in induced sputum, a surrogate of airway inflammation. However, these anti-inflammatory effects are yet to be confirmed in another robust study directly assessing inflammatory markers in bronchial sub-mucosa.

METHODS/DESIGN

An international, 16-week, randomized, double-blind, placebo-controlled, parallel-group study investigating the effects of roflumilast 500 μg once-daily versus placebo on inflammatory parameters in bronchial biopsy tissue specimens, sputum and blood serum. One hundred and fifty patients with COPD and chronic bronchitis for at least 12 months will be recruited into the study and randomized in a 1:1 ratio to receive either roflumilast or placebo. The primary endpoint will be the number of CD8+ cells (cell counts per mm2) in bronchial biopsy tissue specimens (sub-mucosa) and the key secondary endpoint will be the number of CD68+ cells (cell counts per mm2), assessed by indirect immunohistochemistry.

DISCUSSION

It is hypothesized that treatment with roflumilast reduces the characteristic inflammation found in the airways of patients with moderate-to-severe COPD, compared with placebo. The design of the present study has built on the work of previous bronchial biopsy studies available in the literature. It is hoped that it will reveal the cellular mechanisms underlying the anti-inflammatory effects of roflumilast and identify potentially important biomarkers and other surrogate endpoints in patients with COPD. The design and rationale for this trial are described herein.

Real time RT-PCR analysis of inflammatory mediator expression in recurrent airway obstruction-affected horses

The goal of the present study was to investigate mRNA expression levels of several cytokines and inflammatory mediators in broncho-alveolar lavage (BAL) fluid and respiratory epithelium in recurrent airway obstruction (RAO)-affected horses. RAO, also called heaves, is a common, performance-limiting, equine respiratory disease with clinical signs and pathophysiological similarities to human asthma, and characterized by bronchospasm, neutrophilic infiltration and increased mucus in the airways. Six RAO-affected horses were examined twice within 15 days and seven clinically healthy horses were examined for comparison. Quantitative real-time RT-PCR was used to assess mRNA expression of the inflammatory mediators IL-1β, IL-6, IL-8, IL-13, IL-17, TNFα, INFγ, TGFβ1, NFκ-β and TRL4 in bronchial biopsies and in BAL fluid. Gene expression levels were then compared with clinical signs, endoscopic examination, complete blood cell count, cytology of BAL fluid, histological examination of bronchial tissue and bacteriological and mycological examinations. Expression of IL1β, IL8, TLR4, TNFα, TGFβ1 and NFkβ transcripts was significantly up-regulated in RAO-affected compared to healthy horses. A similar trend, albeit not significant, was showed for IL17 and INFγ. A highly significant correlation was observed among IL-1β, IL8, TGFβ1, NFkβ, TRL4, and INFγ expression patterns as well as between expression levels of these genes and clinical parameters. In the present study, the comparison between clinically healthy and RAO-affected horses gave new insights on the cytokine expression in equine health and disease status. The identification of cytokines implicated in the pathogenesis of RAO may contribute to the diagnosis and treatment of this disease.

Quantitative microscopy of the lung: a problem-based approach. Part 2: stereological parameters and study designs in various diseases of the respiratory tract

Design-based stereology provides efficient methods to obtain valuable quantitative information of the respiratory tract in various diseases. However, the choice of the most relevant parameters in a specific disease setting has to be deduced from the present pathobiological knowledge. Often it is difficult to express the pathological alterations by interpretable parameters in terms of volume, surface area, length, or number. In the second part of this companion review article, we analyze the present pathophysiological knowledge about acute lung injury, diffuse parenchymal lung diseases, emphysema, pulmonary hypertension, and asthma to come up with recommendations for the disease-specific application of stereological principles for obtaining relevant parameters. Worked examples with illustrative images are used to demonstrate the work flow, estimation procedure, and calculation and to facilitate the practical performance of equivalent analyses.

Endobronchial biopsy: a guide for asthma therapy selection in the era of bronchial thermoplasty

OBJECTIVE

Bronchial thermoplasty (BT) reduces airway smooth muscle in patients with severe asthma. We developed a novel standardized histologic grading system assessing inflammation and structural remodeling on endobronchial biopsy (EBBx) in severe persistent asthma and evaluated airway structure before and after BT. In addition, we correlated invasive and non-invasive inflammatory markers in severe persistent asthma.

METHODS

Thirty-three patients with severe persistent asthma underwent bronchoscopy, including bronchoalveolar lavage (BAL) and diagnostic EBBx. The control group (N = 41) underwent EBBx for other clinical indications. Biopsies were graded for airway inflammation and epithelial and submucosal structural features. We also evaluated airway histology in three patients before and after BT.

RESULTS

Compared to the control group, patients with severe persistent asthma more often had intraepithelial eosinophils and lymphocytes (67% vs. 17% and 61% vs. 27%; p < .001 and p = .005, respectively) and prominent smooth muscle and goblet cell hyperplasia (88% vs. 29% and 47% vs. 22%, p < .001 and p = .004, respectively). Other features including epithelial denudation and basement membrane thickening were not significantly different. Following BT, airway smooth muscle was no longer prominent due to partial replacement by fibrosis. Increased submucosal eosinophilic inflammation and BAL eosinophilia correlated with exhaled nitric oxide (eNO, p = .05 for both).

CONCLUSIONS

We developed a clinically applicable standardized histologic grading system which identified structural but not inflammatory changes before and after BT in severe persistent asthmatics. Additionally, we demonstrated that eNO is representative of submucosal eosinophilia in this population. This semi-quantitative assessment will be useful for practicing pathologists assessing EBBx from severe persistent asthma patients for diagnostic and clinical research purposes.

Inhaled steroids modulate extracellular matrix composition in bronchial biopsies of COPD patients: a randomized, controlled trial

RATIONALE

Smoking and inflammation contribute to the pathogenesis of chronic obstructive pulmonary disease (COPD), which involves changes in extracellular matrix. This is thought to contribute to airway remodeling and airflow obstruction. We have previously observed that long-term treatment with inhaled corticosteroids can not only reduce bronchial inflammation, but can also attenuate lung function decline in moderate-severe COPD. We hypothesized that inhaled corticosteroids and current smoking modulate bronchial extracellular matrix components in COPD.

OBJECTIVE

To compare major extracellular matrix components (elastic fibers; proteoglycans [versican, decorin]; collagens type I and III) in bronchial biopsies 1) after 30-months inhaled steroids treatment or placebo; and 2) between current and ex-smokers with COPD.

METHODS

We included 64 moderate-severe, steroid-naive COPD patients (24/40 (ex)-smokers, 62±7 years, 46 (31-54) packyears, post-bronchodilator forced expiratory volume in one second (FEV1) 62±9% predicted) at baseline in this randomized, controlled trial. 19 and 13 patients received 30-months treatment with fluticasone or placebo, respectively. Bronchial biopsies collected at baseline and after 30 months were studied using (immuno)histochemistry to evaluate extracellular matrix content. Percentage and density of stained area were calculated by digital image analysis.

RESULTS

30-Months inhaled steroids increased the percentage stained area of versican (9.6% [CI 0.9 to 18.3%]; p = 0.03) and collagen III (20.6% [CI 3.8 to 37.4%]; p = 0.02) compared to placebo. Increased collagen I staining density correlated with increased post-bronchodilator FEV1 after inhaled steroids treatment (Rs = 0.45, p = 0.04). There were no differences between smokers and ex-smokers with COPD in percentages and densities for all extracellular matrix proteins.

CONCLUSIONS

These data show that long-term inhaled corticosteroids treatment partially changes the composition of extracellular matrix in moderate-severe COPD. This is associated with increased lung function, suggesting that long-term inhaled steroids modulate airway remodeling thereby potentially preventing airway collapse in COPD. Smoking status is not associated with bronchial extracellular matrix proteins.

TRIAL REGISTRATION

ClinicalTrials.gov NCT00158847.

CD8(+) T cells characterize early smoking-related airway pathology in patients with asthma

BACKGROUND

Smoking in asthma occurs frequently and is associated with increased symptom severity, an impaired response to corticosteroids, and accelerated lung function decline. Airway pathology in smoking asthmatics is characterized by neutrophilia and epithelial changes such as goblet cell hyperplasia and increased proliferation. Bronchial CD8(+) T cells are implicated in lung function decline in asthma and COPD. We hypothesized that smoking modifies airway inflammation in asthma by increasing the number of CD8(+) T cells at an early stage.

OBJECTIVES & METHODS

To study effects of smoking on airway pathology in bronchial biopsies from atopic patients with controlled intermittent or mild persistent asthma (12 smokers, 9.7 py and 11 never-smokers, 0.0 py; 20-50 yrs; FEV1 > 70% predicted; PC20MCh < 8 mg/mL, no ICS) using immunohistochemistry.

RESULTS

Smoking asthmatics showed higher numbers of bronchial CD8(+) T cells (55.8 vs 23.9 cells/0.1 mm(2); p = 0.001) and CD68(+) macrophages (7.5 vs 4.6 cells/0.1 mm(2), p = 0.012), and a lower CD4(+)/CD8(+) cell ratio (0.16 vs 0.40; p = 0.007) compared with non-smoking asthmatics, but no difference in neutrophils. Furthermore, the % intact epithelium was higher in smoking asthmatics (49.3 vs 23.3, p = 0.001).

CONCLUSION

Smoking asthmatics with a limited smoking history show a distinct pattern of airway pathology characterized by a bronchial infiltrate of CD8(+) T cells and CD68(+) macrophages, and epithelial remodelling resembling COPD-like features. This raises the hypothesis that early presence of CD8(+) T cells contributes to disease progression in smoking asthmatics.

Involvement of interleukin-17 during lymphocytic bronchiolitis in lung transplant patients

BACKGROUND

Interleukin-17 (IL-17) is involved in autoimmune and chronic pulmonary diseases and linked with neutrophilic inflammation. Azithromycin reduces and prevents broncholaveolar lavage (BAL) neutrophilia after lung transplantation (LTx). In this investigation we assessed the involvement of IL-17 in different post-transplant complications in human LTx biopsies.

METHODS

Immunohistochemical staining against IL-17A was performed on biopsies of LTx patients with either chronic rejection, acute A-grade rejection (A > 2B0), lymphocytic bronchiolitis (LB), infection, and stable patients. Biopsies of 7 patients with LB were stained before and after azithromycin treatment. IL-17+ cells were quantified as number per square millimeter of lamina propria. Double staining with CD4/CD8 was performed to determine the origin of IL-17.

RESULTS

In the LB group, biopsies showed a significant presence of IL-17+ cells/mm2 of lamina propria compared with the stable, acute A-grade/chronic rejection and infection groups (p < 0.0001). The number of IL-17+ cells on biopsy correlated with percent BAL (%BAL) neutrophilia (r = 0.34, p = 0.0056). Azithromycin reduced both %BAL neutrophilia and IL-17+ cells (both p = 0.016) in the LB group. CD8+ cells were the major source of IL-17.

CONCLUSIONS

IL-17+ / CD8+ cells are present in LB after LTx but not in acute A-grade/chronic rejection nor during infection. Moreover, azithromycin significantly decreased the number of IL-17+ cells in the airway wall, which may further explain its effect on BAL neutrophilia.

Defining critical roles for NF-κB p65 and type I interferon in innate immunity to rhinovirus

The importance of NF-κB activation and deficient anti-viral interferon induction in the pathogenesis of rhinovirus-induced asthma exacerbations is poorly understood. We provide the first in vivo evidence in man and mouse that rhinovirus infection enhanced bronchial epithelial cell NF-κB p65 nuclear expression, NF-κB p65 DNA binding in lung tissue and NF-κB-regulated airway inflammation. In vitro inhibition of NF-κB reduced rhinovirus-induced pro-inflammatory cytokines but did not affect type I/III interferon induction. Rhinovirus-infected p65-deficient mice exhibited reduced neutrophilic inflammation, yet interferon induction, antiviral responses and virus loads were unaffected, indicating that NF-κB p65 is required for pro-inflammatory responses, but redundant in interferon induction by rhinoviruses in vivo. Conversely, IFNAR1^−/− mice exhibited enhanced neutrophilic inflammation with impaired antiviral immunity and increased rhinovirus replication, demonstrating that interferon signalling was critical to antiviral immunity. We thus provide new mechanistic insights into rhinovirus infection and demonstrate the therapeutic potential of targeting NF-κB p65 (to suppress inflammation but preserve anti-viral immunity) and type I IFN signalling (to enhance deficient anti-viral immunity) to treat rhinovirus-induced exacerbations of airway diseases.

Toll-like receptors 2, 3 and 4 and thymic stromal lymphopoietin expression in fatal asthma

BACKGROUND

Airway inflammation in asthma involves innate immune responses. Toll-like receptors (TLRs) and thymic stromal lymphopoietin (TSLP) are thought to be involved in airway inflammation, but their expression in asthmatics' both large and small airways has not been investigated.

OBJECTIVE

To analyse the expression of TLR2, TLR3, TLR4 and TSLP in large and small airways of asthmatics and compare their expression in smoking and non-smoking asthmatics; to investigate whether TLR expression is associated with eosinophilic or neutrophilic airway inflammation and with Mycoplasma pneumoniae and Chlamydophila pneumoniae infection.

METHODS

Using immunohistochemistry and image analysis, we investigated TLR2, TLR3, TLR4 and TSLP expression in large and small airways of 24 victims of fatal asthma, FA, (13 non-smokers, 11 smokers) and nine deceased control subjects (DCtrl). TLRs were also measured in 18 mild asthmatics (MA) and 12 healthy controls (HCtrl). M. pneumoniae and C. pneumoniae in autopsy lung tissue were analysed using real-time polymerase chain reaction. Airway eosinophils and neutrophils were measured in all subjects.

RESULTS

Fatal asthma patients had higher TLR2 in the epithelial and outer layers of large and small airways compared with DCtrls. Smoking asthmatics had lower TLR2 levels in the inner and outer layers of the small airways than non-smoking asthmatics. TSLP was increased in the epithelial and outer layers of the large airways of FA. FA patients had greater TLR3 expression in the outer layer of large airways and greater TLR4 expression in the outer layer of small airways. Eosinophilic airway inflammation was associated with TLR expression in the epithelium of FA. No bacterial DNA was detected in FA or DCtrls. MA and HCtrls had only a small difference in TLR3 expression.

CONCLUSIONS AND CLINICAL RELEVANCE

Increased expression of TLR 2, 3 and 4 and TSLP in fatal asthma may contribute to the acute inflammation surrounding asthma deaths.

Diagnostic tools assessing airway remodelling in asthma

Asthma is an inflammatory disease of the lower airways characterised by the presence of airway inflammation, reversible airflow obstruction and airway hyperresponsiveness and alterations on the normal structure of the airways, known as remodelling. Remodelling is characterised by the presence of metaplasia of mucous glands, thickening of the lamina reticularis, increased angiogenesis, subepithelial fibrosis and smooth muscle hypertrophy/hyperplasia. Several techniques are being optimised at present to achieve a suitable diagnosis for remodelling. Diagnostic tools could be divided into two groups, namely invasive and non-invasive methods. Invasive techniques bring us information about bronchial structural alterations, obtaining this information directly from pathological tissue, and permit measure histological modification placed in bronchi layers as well as inflammatory and fibrotic cell infiltration. Non-invasive techniques were developed to reduce invasive methods disadvantages and measure airway remodelling-related markers such as cytokines, inflammatory mediators and others. An exhaustive review of diagnostic tools used to analyse airway remodelling in asthma, including the most useful and usually employed methods, as well as the principal advantages and disadvantages of each of them, bring us concrete and summarised information about all techniques used to evaluate alterations on the structure of the airways. A deep knowledge of these diagnostic tools will make an early diagnosis of airway remodelling possible and, probably, early diagnosis will play an important role in the near future of asthma.

Novel outcomes and end points: biomarkers in chronic obstructive pulmonary disease clinical trials

Biomarker development in chronic obstructive pulmonary disease (COPD) is a nascent field, in part because of the complexity underlying COPD pathogenesis. The objective of this review is to provide examples of how biomarkers may be effectively applied in clinical trials of COPD by limiting their use to specific contexts and using them to answer well delineated questions. Types of novel outcomes or "biomarkers" that may be useful in clinical trials in COPD include analyses performed on bronchoscopically obtained samples, sputum, exhaled gases, blood, and urine and "ex vivo" assays performed using biological samples obtained from trial participants. These novel biological outcomes are rarely useful as primary end points in phase III clinical trials in COPD, because they are not typically recognized by the U.S. Food and Drug Administration or other regulatory agencies. More commonly, the applications of these outcomes include "proof-of-concept" decisions, demonstration that the intervention had the intended pharmacologic or biological effect, identification of patient subgroups that benefit most, and safety monitoring. Examples given in this review include outcomes used in a phase IIA study of an inhaled small molecule inhibitor of epidermal growth factor receptor. Large observational studies of COPD, including the ECLIPSE, COPDGene, and SPIROMICS studies will further inform our use of biomarkers in COPD clinical trials. To encourage the application of novel biomarkers in clinical trials, the Food and Drug Administration has developed a new process for biomarker "qualification." This process has been designed to be more efficient and to promote consensus building and sharing of preclinical data.

Limited short-term steroid responsiveness is associated with thickening of bronchial basement membrane in severe asthma

BACKGROUND

The clinical manifestations of bronchial remodeling in asthma and the potential impact of this process on lung function remain unclear. We aimed to determine whether the presence of pathologic features of airway remodeling in patients with asthma was associated with steroid responsiveness in the short term.

METHODS

Sixty-three consecutive patients with severe asthma with chronic airflow impairment (post-bronchodilator FEV(1) < 80% predicted values) were recruited, clinically characterized, and had an initial bronchoscopy where endobronchial biopsy and BAL were performed. BAL cellular content was reported and reticular basement membrane (RBM) thickness was measured by validated repeated measures. Patients were then treated with 1 mg/kg/d of methyl prednisone, directly administered IV, for 10 days. A threshold of 15% FEV(1) improvement was used to discriminate responsive (group 1) and refractory patients (group 2).

RESULTS

Thirty-eight patients had a steroid responsiveness > 15% (group 1) and a thinner RBM at the biopsy level (5.78 ± 2.0 μm vs 7.60 ± 2.2 μm; P = .001) compared with nonsteroid responsive group 2 patients as defined. The best predictors for being unresponsive were no long-term treatment with oral steroids and increased RBM thickness. The associated receiver operating characteristic curve indicated that RBM thickness could predict steroid responsiveness below 15% with an area under the curve of 0.747 (P = .0002) at a threshold of 7 μm.

CONCLUSIONS

Features of airway remodeling are associated with limited short-term steroid responsiveness in severe asthma.

[Airway remodeling in asthma: clinical and functional correlates]

Asthma is a chronic inflammatory disorder of the airways associated with bronchial hyperresponsiveness and permanent structural changes. Asthma can cause progressive lung impairment with a progressive decline of lung function leading to partially reversible or irreversible airway obstruction. These structural changes are called airway remodelling including loss of epithelial integrity, thickening of basement membrane, subepithelial fibrosis, goblet cell and submucosal gland enlargement, increase smooth muscle mass, decreased cartilage integrity and increased airway vascularity. These remodelling changes contribute to thickening of airway walls and consequently lead to airway narrowing, bronchial hyperresponsiveness, airway oedema and mucous hypersecretion. Airway remodelling is associated with a poorer clinical outcome among patients with asthma. Early diagnosis and prevention has the potential to decrease disease severity, to improve control and to prevent disease expression.

Airway inflammation in atopic patients: a comparison of the upper and lower airways

OBJECTIVE

The purpose of this study was to understand and assess the inflammatory response within the upper and lower airways in patients suffering from both asthma and allergic rhinitis. Study Design. Cross-sectional study. Setting. A laboratory-based study of patients with allergic rhinitis and asthma.

SUBJECTS AND METHODS

Glycol methacrylate resin-embedded specimens from 10 patients with allergic rhinitis and asthma taken from the nose and bronchi were assessed by immunohistochemistry. Monoclonal antibodies directed against specific cell markers for mast cells (AA1), eosinophils (EG2), neutrophils (NOE), and lymphocytes (CD3(+), CD4(+), CD8(+)) were studied. Cells were counted blind (as cells/mm(2)) in the submucosal matrix. Mann-Whitney U test was used for analyses. P values of .05 or lower were considered statistically significant.

RESULTS

There was a significant increase in CD4(+) (P = .05) and CD8(+) cell counts (P = .001) in the lower airway compared to the upper airway. There were no differences between the 2 groups in the number of neutrophils, mast cells, eosinophils, and the CD3(+) cell counts.

CONCLUSION

The upper and lower airways have parallel inflammation with possible bidirectional extension of inflammation in patients suffering from asthma and allergic rhinitis. There is increased lymphocytic infiltration in the lower airway, suggesting a possible preponderance for development and maintenance of allergic disease in the lower airway.

Tenascin-C and alpha-smooth muscle actin positive cells are increased in the large airways in patients with COPD

BACKGROUND

Chronic obstructive pulmonary disease (COPD) is characterized by inflammation and remodeling of the lungs. This results in alterations in extracellular matrix (ECM) and structural changes leading to airflow obstruction. We studied the expression of tenascin-C (Tn-C) and alpha smooth muscle actin (α-SMA), which act as a marker of myofibroblasts, in large airways from COPD patients. Our aim was to elucidate whether this expression correlated with smoking or with disease development.

METHODS

Bronchoscopy was performed on 20 COPD patients (mean age 56 years; range 39-61; FEV1/FVC < 70% and FEV1 median 53% (range 33-69) of predicted). Age and smoking matched smokers (S) without COPD (n = 13) and age matched non-smokers (NS) (n = 14) served as controls. Bronchial mucosal biopsies were analyzed by immunohistochemistry. The distribution of Tn-C expression was assessed and graded in three levels, and the number of spindle shaped cells staining positive for α-SMA were counted.

RESULTS

Biopsies from COPD patients had more (P < 0.001) Tn-C expression than the two control groups. A significantly (P < 0.05) increased number of spindle shaped cells expressing α-SMA was observed in COPD patients compared with the controls. Smokers and nonsmokers did not differ in this respect. The expression of Tn-C correlated positively (P < 0.001) to the number of α-SMA positive cells.

CONCLUSIONS

We demonstrate increased expression of Tn-C and α-SMA positive cells in the large airways in COPD. This was not associated to smoking per se, but to the presence of airway obstruction. Our findings add new information regarding remodeling characteristics and highlight the large airways as a potential site for airways obstruction in COPD.

Proteomics of epithelial lining fluid obtained by bronchoscopic microprobe sampling

Epithelial lining fluid (ELF) forms a thin fluid layer that covers the mucosa of the alveoli, the small airways, and the large airways. Since it constitutes the first barrier between the lung and the outer world, it is an interesting target for proteomics studies that focus on lung disease. Bronchoscopic microprobe (BMP) sampling of ELF uses small probes with an absorptive tip that are introduced bronchoscopically. In contrast to other methods used so far for the collection of biofluids from the lung (e.g., bronchoalveolar lavage fluid, induced sputum), this technique has the advantage that ELF is not diluted and contains high concentrations of biomolecules. In addition, the investigated location in the tracheobronchial tree is well defined, and there is no contamination with oropharyngeal bacteria or saliva. Despite occasional blood contamination of the probes by scratching the mucosa of the airways, the proteomic analysis of microprobe-sampled ELF opens new possibilities for research in lung diseases. Our work focuses particularly on the induction and progression of cigarette smoke-induced Chronic Obstructive Pulmonary Disease (COPD). In this chapter, we describe the practical aspects of sampling ELF followed by a detailed description of proteomics analysis by LC-MS/MS after protein separation by SDS-PAGE and in-gel digestion. As an example, we apply this proteomic platform to the identification and quantification of proteins in ELF from COPD patients and healthy subjects.

Endobronchial and transbronchial biopsies in children

The aim of this review is to describe the indications, techniques and side effects of bronchial biopsies in children. At present, two different types of bronchial biopsies are currently used: endobronchial biopsies (EBBs) and transbronchial biopsies (TBBs). These procedures are becoming more diffuse thanks to the extensive use of pediatric fiber optic bronchoscopes (FOBs). EBBs can be used to obtain specimens from the bronchial wall and from endobronchial masses, while TBBs permit collection of samples from peripheral lung parenchyma. The use of FOBs with a working channel of more than 2 mm in diameter allows the utilization of adequate forceps to obtain good specimens, even in children less than 2 years of age. This amplifies the research field of persistent lung diseases, such as cystic fibrosis and bronchial asthma. The main contraindication to perform bronchial biopsies is bleeding disorders. For research purposes, it is mandatory to obtain the approval of the Institutional Ethical Committee, the signed consent of the parents and the age-appropriate assent of the child.

Expression of the T helper 17-associated cytokines IL-17A and IL-17F in asthma and COPD

Background:

Asthma and COPD are characterized by airway dysfunction and inflammation. Neutrophilic airway inflammation is a common feature of COPD and is recognized in asthma, particularly in severe disease. The T helper (Th) 17 cytokines IL-17A and IL-17F have been implicated in the development of neutrophilic airway inflammation, but their expression in asthma and COPD is uncertain.

Methods:

We assessed IL-17A and IL-17F expression in the bronchial submucosa from 30 subjects with asthma, 10 ex-smokers with mild to moderate COPD, and 27 nonsmoking and 14 smoking control subjects. Sputum IL-17 concentration was measured in 165 subjects with asthma and 27 with COPD.

Results:

The median (interquartile range) IL-17A cells/mm² submucosa was increased in mild to moderate asthma (2.1 [2.4]) compared with healthy control subjects (0.4 [2.8]) but not in severe asthma (P = .04). In COPD, IL-17A⁺ cells/mm² submucosa were increased (0.5 [3.7]) compared with nonsmoking control subjects (0 [0]) but not compared with smoking control subjects (P = .046). IL-17F⁺ cells/mm² submucosa were increased in severe asthma (2.7 [3.6]) and mild to moderate asthma (1.6 [1.0]) compared with healthy controls subjects (0.7 [1.4]) (P = .001) but was not increased in subjects with COPD. IL-17A and IL-17F were not associated with increased neutrophilic inflammation, but IL-17F was correlated with the submucosal eosinophil count (rs = 0.5, P = .005). The sputum IL-17 concentration in COPD was increased compared with asthma (2 [0-7] pg/mL vs 0 [0-2] pg/mL, P < .0001) and was correlated with post-bronchodilator FEV₁% predicted (r = −0.5, P = .008) and FEV₁/FVC (r = −0.4, P = .04).

Conclusions:

Our findings support a potential role for the Th17 cytokines IL-17A and IL-17F in asthma and COPD, but do not demonstrate a relationship with neutrophilic inflammation.

Biomarkers in COPD

Although there is increasing interest in using pulmonary biomarkers for a more complete and clinically relevant assessment of COPD and a plethora of biomarkers are becoming available, there is little information regarding their reproducibility and correlation with other outcome measurements in COPD. The lack of well-validated biomarkers that can be used for monitoring disease activity, predicting future clinical outcomes and the effect of therapeutic interventions highlights the factual need to identify new biomarkers in COPD. It is likely that, using what is called 'integrative functional informatics', which is a novel direction in the interfacing and integration of different technologies (genomics, proteomics, metabolomics and metabonomics, pharmacogenetics, and integrative approaches) for collection and analysis of data on biomarkers, we will be able to identify robust, reliable, and reproducible biomarkers in COPD.

Effects of budesonide and formoterol on allergen-induced airway responses, inflammation, and airway remodeling in asthma

BACKGROUND

Combining inhaled corticosteroids with long-acting beta(2)-agonists results in improved asthma symptom control and fewer asthma exacerbations compared with those seen after inhaled corticosteroids alone. However, there are limited data as to whether these beneficial effects are due to enhanced anti-inflammatory actions or whether such combination therapies affect airway remodeling in patients with asthma.

OBJECTIVE

We sought to determine the effects of inhaled budesonide/formoterol combination therapy versus inhaled budesonide alone or inhaled placebo on allergen-induced airway responses, airway inflammation, and airway remodeling.

METHODS

Fourteen asthmatic subjects with dual responses after allergen inhalation were included in this prospective, randomized, double-blind, 3-period crossover study. Outcomes included early and late asthmatic responses, changes in airway responsiveness, sputum eosinophilia measured before and after allergen challenge, numbers of airway submucosal myofibroblasts, and smooth muscle area measured before and after study treatment.

RESULTS

Allergen-induced sputum eosinophilia was significantly reduced by combination treatment to a greater extent than by budesonide alone. Allergen inhalation resulted in a significant increase in submucosal tissue myofibroblast numbers and produced a significant decrease in percentage smooth muscle area. Combination therapy, but not budesonide monotherapy, significantly attenuated these changes in myofibroblast numbers and smooth muscle area.

CONCLUSIONS

The effects on allergen-induced changes in sputum eosinophils, airway myofibroblast numbers, and smooth muscle seen with combination therapy suggest that the benefits associated with this treatment might relate to effects on airway inflammation and remodeling. The attenuation of early asthmatic responses and airway hyperresponsiveness by combination treatment was likely due to the known functional antagonistic effect of formoterol.

Topographical distribution of bronchial eosinophilia: significance for biopsy diagnosis

Field-by-field (0.324 x 0.09 microM) counts of eosinophils were applied to the lamina propria of cartilaginous bronchi from 47 Los Angeles and 22 Miami residents 11 to 30 years of age who died suddenly from violence. A highly variable topographical distribution was found that appeared to be due mainly to variations in confluent eosinophil-positive fields and "hot spots" (>or=3 eosinophils per field). Since biopsy is the gold standard for the diagnosis of bronchial eosinophilia, there is a need to resolve the problem of non-uniformity. New measurements applicable to biopsy diagnosis are presented having potential usefulness for providing insight into the severity and topographical distribution of eosinophilia within bronchi that are the sites of biopsy. The additional finding of a 30.4% incidence of moderate to marked eosinophilia (>1.5 eosinophils/mm reticular basement membrane) suggests a high level of asthma or asthmatic-like disease in the young subjects of this study.

Montelukast and bronchial inflammation in asthma: a randomised, double-blind placebo-controlled trial

BACKGROUND

Examination of bronchoalveolar lavage, induced sputum, and peripheral blood indicate that cysteinyl leukotriene receptor blockers decrease inflammatory cells in asthma but these do not examine airway tissue per se.

OBJECTIVES

Our objective was to determine the effect of montelukast, a leukotriene receptor antagonist, on airway tissue inflammatory cells by direct bronchoscopic examination of the bronchial mucosa.

METHODS

Adult subjects with mild asthma (pre-bronchodilator FEV(1)> or =70% predicted; PC(20) of < or =4 mg/mL) were given 10mg/day oral montelukast (N=38) or placebo (N=37) for 6 weeks. Bronchial mucosal eosinophils and mast cells were identified and counted.

RESULTS

Change from baseline in numbers of biopsy EG2+ ("activated") eosinophils was the primary endpoint; numbers of total (chromotrope 2R+) eosinophils and (tryptase+) mast cells were secondary. Unexpectedly, there were many patients with zero EG2+ eosinophils at baseline. There was a within-group decrease in EG2+ cells, from 13.54 cells/mm (at baseline) to 0.79 cells/mm at 6 weeks in the montelukast group (LS mean change; 95% confidence interval=-13.59 [-25.45, -1.74]cells/mm; P<0.05), a change not observed in the placebo group (-1.17 [-13.26, 10.91]cells/mm; NS). The zero-inflated Poisson statistical model demonstrated that montelukast significantly reduced post-treatment EG2+ cells by 80% compared with placebo (95% CI [70.6-86.8%]; P<0.0001). The data for total eosinophils showed similar changes. The reduction in mast cell numbers was 12% (95% CI [7.9, 16.0]; P<0.0001).

CONCLUSION

Direct examination of airway tissue confirms that montelukast decreases the number of eosinophils and mast cells in asthma.

Quality of bronchial biopsies for morphology study and cell sampling: a comparison of asthmatic and healthy subjects

BACKGROUND

Bronchial biopsies are widely used for histopathological, primary cell culture and genetic studies, but very few reports have evaluated their quality.

OBJECTIVES AND METHODS

The present project evaluated the quality (using a scoring system) and the general morphology of a pool of six bronchial biopsy specimens taken from three different sampling sites (the lobar, segmental and subsegmental carinae) in 27 subjects (13 asthmatic subjects and 14 healthy controls). The present study also assessed quantitative measurements of structural changes related to asthma.

RESULTS

In total, 94.4% of the biopsy attempts had enough tissue to be processed. From these, 61.7% were scored with a good to excellent quality, while 76.5% presented smooth muscle bundles and 40.5% had an intact epithelium wall. The data also confirmed the structural changes observed in asthma, such as increased apparent thickening of the basement membrane, reduced amounts of smooth muscle for healthy controls and decreased percentage of intact epithelium for asthmatic subjects.

CONCLUSION

A pool of six bronchial biopsy specimens can provide tissue of excellent quality in both asthmatic and healthy subjects and, consequently, a valuable sample for morphological analysis of mucosal structures.