The role of small airway disease in asthma

TMT-based quantitative proteomics revealed protective efficacy of Icariside II against airway inflammation and remodeling via inhibiting LAMP2, CTSD and CTSS expression in OVA-induced chronic asthma mice

BACKGROUND

Asthma is a chronic inflammatory disorder in airways with typical pathologic features of airflow limitation, airway inflammation and remodeling. Icariside II (IS), derived from herbal medicine Herba Epimedii, exerts an anti-inflammatory property. However, underlying mechanisms with specifically targeted molecular expression by IS in asthma have not been fully understood, and whether IS could inhibit remodeling and EMT still remains unclear.

PURPOSE

The study aimed to clarify therapeutic efficacy of IS for attenuating airway inflammation and remodeling in asthma, and illustrate IS-regulated specific pathway and target proteins through TMT-based quantitative proteomics.

STUDY DESIGN AND METHODS

Murine model of chronic asthma was constructed with ovalbumin (OVA) sensitization and then challenge for 8 weeks. Pulmonary function, leukocyte count in bronchoalveolar lavage fluid (BALF), lung histopathology, inflammatory and fibrotic cytokines, and markers of epithelial-mesenchymal transition (EMT) were evaluated. TMT-based quantitative proteomics were performed on lung tissues to explore IS-regulated proteins.

RESULTS

IS contributed to alleviative airway hyperresponsiveness (AHR) evidenced by declined R_L and increased Cdyn. After IS treatment, we observed a remarked down-regulation of leukocyte count, inflammatory cytokines in BALF, and peribronchial inflammation infiltration. Goblet cell hyperplasia, mucus secretion and peribronchial collagen deposition were attenuated, with the level of TGF-β and MMP-9 in BALF declined. Furthermore, IS induced a rise of Occludin and E-cadherin and a decline of N-cadherin and α-SMA in lung tissues. These results proved the protective property of IS against airway inflammation, remodeling and EMT. To further investigate underlying mechanisms of IS in asthma treatment, TMT-based quantitative proteomics were performed and 102 overlapped DEPs regulated by IS were identified. KEGG enrichment exhibited these DEPs were enriched in lysosome, phagosome and autophagy, in which LAMP2, CTSD and CTSS were common DEPs. WB, q-PCR and IHC results proofed expressional alteration of these proteins. Besides, IS could decrease Beclin-1 and LC3B expression with increasing p62 expression thus inhibiting autophagy.

CONCLUSIONS

The study demonstrated IS could ameliorate AHR, airway inflammation, remodeling and EMT in OVA-induced chronic asthma mice. Our research was the first to reveal that inhibition of LAMP2, CTSD and CTSS expression in autophagy contributed to the therapeutic efficacy of IS to asthma.

Mast Cell Tryptase Promotes Airway Remodeling by Inducing Anti-Apoptotic and Cell Growth Properties in Human Alveolar and Bronchial Epithelial Cells

Bronchial and alveolar remodeling and impaired epithelial function are characteristics of chronic respiratory diseases. In these patients, an increased number of mast cells (MCs) positive for serine proteases, tryptase and chymase, infiltrate the epithelium and alveolar parenchyma. However, little is known regarding the implication of intraepithelial MCs on the local environment, such as epithelial cell function and properties. In this study, we investigated whether MC tryptase is involved in bronchial and alveolar remodeling and the mechanisms of regulation during inflammation. Using novel holographic live cell imaging, we found that MC tryptase enhanced human bronchial and alveolar epithelial cell growth and shortened the cell division intervals. The elevated cell growth induced by tryptase remained in a pro-inflammatory state. Tryptase also increased the expression of the anti-apoptotic protein BIRC3, as well as growth factor release in epithelial cells. Thus, our data imply that the intraepithelial and alveolar MC release of tryptase may play a critical role in disturbing bronchial epithelial and alveolar homeostasis by altering cell growth-death regulation.

The effects of benralizumab on airway geometry and dynamics in severe eosinophilic asthma: a single-arm study design exploring a functional respiratory imaging approach

BACKGROUND

Severe eosinophilic asthma (SEA) is characterised by elevated blood/sputum eosinophil counts and airway inflammation, which can lead to mucus plug-mediated airway obstruction, increased exacerbation frequency, declines in lung function, and death. Benralizumab targets the alpha-subunit of the interleukin-5 receptor found on eosinophils, leading to rapid and near complete eosinophil depletion. This is expected to result in reduced eosinophilic inflammation, reduced mucus plugging and improved airway patency and airflow distribution.

METHODS

BURAN is an interventional, single-arm, open-label, uncontrolled, prospective, multicentre study during which participants will receive three 30 mg subcutaneous doses of benralizumab at 4-week intervals. This study will use functional respiratory imaging (FRI), a novel, quantitative method of assessing patients' lung structure and function based on detailed, three-dimensional models of the airways, with direct comparison of images taken at Weeks 0 and 13. Patients aged ≥ 18 years with established SEA who may be receiving oral corticosteroids and/or other asthma controller medications, who are inadequately controlled on inhaled corticosteroid-long-acting β₂-agonist therapies and who have had ≥ 2 asthma exacerbations in the previous 12 months will be included. The objectives of BURAN are to describe changes in airway geometry and dynamics, measured by specific image-based airway volume and other FRI endpoints, following benralizumab therapy. Outcomes will be evaluated using descriptive statistics. Changes in FRI parameters, mucus plugging scores and central/peripheral ratio will be quantified as mean percent change from baseline (Week 0) to Week 13 (± 5 days) and statistical significance will be evaluated using paired t-tests. Relationships between FRI parameters/mucus plugging scores and conventional lung function measurements at baseline will be assessed with linear regression analyses for associations between outcomes, scatterplots to visualise the relationship, and correlation coefficients (Spearman's rank and Pearson's) to quantify the strength of these associations.

CONCLUSIONS

The BURAN study will represent one of the first applications of FRI-a novel, non-invasive, highly sensitive method of assessing lung structure, function and health-in the field of biologic respiratory therapies. Findings from this study will increase understanding of cellular-level eosinophil depletion mechanisms and improvements in lung function and asthma control following benralizumab treatment. Trial registration EudraCT: 2022-000152-11 and NCT05552508.

Real-life effects of benralizumab on airway oscillometry in severe eosinophilic asthma

INTRODUCTION

Eosinophil depletion with benralizumab reduces exacerbations and improves disease control and FEV₁ in patients with severe eosinophilic asthma. However, few studies have investigated the effect of biologics on small airways dysfunction (SAD) even though the latter correlates better with poor asthma control and type 2 inflammation.

METHODS

21 GINA-defined severe asthma patients who were treated with benralizumab and who had baseline oscillometry-defined SAD were included in this study. Here, SAD was diagnosed only if patients satisfied both R5-R20≥0.10 kPa/L/s and AX≥1.0 kPa/L. The mean duration of follow-up between pre-benralizumab versus post-benralizumab clinical measurements was 8 months.

RESULTS

Mean values for FEV₁% and FVC% but not FEF_25%-75% significantly increased following benralizumab, along with significant reductions in Asthma Control Questionnaire (ACQ). There were no significant improvements in R5-R20, X5 or AX, while the mean (SEM) PBE count fell to 23 (14) cells/µL. In a responder analysis, n=8/21 and n=12/21 patients experienced improvements exceeding biological variability of 0.04 kPa/L/s and 0.39 kPa/L in R5-R20 and AX, respectively, in severe asthma. N=10/21, n=10/21 and n=11/21 patients experienced improvements in FEV₁, FEF_25-75 and FVC exceeding biological variability of 150 mL, 0.210 L/s and 150 mL, respectively. In contrast, n=15/21 patients experienced an improvement in ACQ greater than minimal clinical important difference of 0.5 units.

CONCLUSION

Eosinophil depletion with benralizumab improves spirometry and asthma control but does not improve spirometry-measured or oscillometry-measured SAD in severe asthma in a real-life setting.

Obesity in women with asthma: Baseline disadvantage plus greater small-airway responsiveness

BACKGROUND

Obesity is known to diminish lung volumes and worsen asthma. However, mechanistic understanding is lacking, especially as concerns small-airway responsiveness. The objective of this study was therefore to compare small-airway responsiveness, as represented by the change in expiratory:inspiratory mean lung density ratios (MLD_e/i , as determined by computed tomography [CT]) throughout methacholine testing in obese versus non-obese women with asthma.

METHODS

Thoracic CT was performed during methacholine bronchoconstriction challenges to produce standardized response curves (SRC: response parameter versus ln[1 + % PD20], where PD20 is the cumulative methacholine dose) for 31 asthma patients (n = 18 non-obese and n = 13 obese patients). Mixed models evaluated obesity effects and interactions on SRCs while adjusting for age and bronchial morphology. Small airway responsiveness as represented by SRC slope was calculated for each third of the MLD_e/i response and compared between groups.

RESULTS

Obesity-associated effects observed during experimental bronchoconstriction included: (i) a significant baseline effect for forced expiratory volume in 1 second with lower values for the obese (73.11 ± 13.44) versus non-obese (82.19 ± 8.78; p = 0.002) groups prior to methacholine testing and (ii) significantly higher responsiveness in small airways as estimated via differences in MLD_e/i slopes (group×ln(1 + % PD20 interaction; p = 0.023). The latter were pinpointed to higher slopes in the obese group at the beginning 2/3 of SRCs (p = 0.004 and p = 0.021). Significant obesity effects (p = 0.035 and p = 0.008) indicating lower forced vital capacity and greater % change in MLD_e/I (respectively) throughout methacholine testing, were also observed.

CONCLUSION

In addition to baseline differences, small-airway responsiveness (as represented by the change in MLD_e/i ) during methacholine challenge is greater in obese women with asthma as compared to the non-obese.

An update on the currently available and emerging synthetic pharmacotherapy for uncontrolled asthma

INTRODUCTION

: The treatment of uncontrolled asthma has improved because of triple therapy that includes a long-acting muscarinic antagonist (LAMA) and biological drugs, but several patients are resistant to corticosteroids and/or cannot achieve adequate asthma control using such therapies.

AREAS COVERED

: Herein, the authors review the current and emerging synthetic pharmacotherapy for uncontrolled asthma to overcome obstacles and limitations of biological therapies. The authors also provide their expert perspectives and opinion on the treatment of uncontrolled asthma.

EXPERT OPINION

: LAMAs should be added to inhaled corticosteroid/long-acting β₂-agonist combinations much earlier than currently recommended by the Global Initiative for Asthma strategy because they can influence the course of small airways disease, reducing lung hyperinflation and improving asthma control. Biological therapies are a major advance in the treatment of severe asthma, but their use is still very limited for several reasons. An alternative to overcome the use of biological therapies is to synthesise compounds that target inflammation-signalling pathways. Several pathways have been identified as potential targets to design either therapeutic or prophylactic drugs against asthma. Some new compounds have already been tested in humans, but results have often been disappointing probably because existing phenotypic and endotypic variants may unpredictably limit the therapeutic value of blocking a specific pathway in most asthmatics, although there may be a substantial benefit for a subgroup of patients.

Lung function and air pollution exposure in adults with asthma in Beijing: a 2-year longitudinal panel study

The effect of air pollution on the lung function of adults with asthma remains unclear to date. This study followed 112 patients with asthma at 3-month intervals for 2 years. The pollutant exposure of the participants was estimated using the inverse distance weight method. The participants were divided into three groups according to their lung function level at every visit. A linear mixed-effect model was applied to predict the change in lung function with each unit change in pollution concentration. Exposure to carbon monoxide (CO) and particles less than 2.5 micrometers in diameter (PM_2.5) was negatively associated with large airway function in participants. In the severe group, exposure to chronic sulfur dioxide (SO2) was negatively associated with post-bronchodilator forced expiratory flow at 50%, between 25% and 75% of vital capacity % predicted (change of 95% CI per unit: -0.34 (-0.55, -0.12), -0.24 (-0.44, -0.03), respectively). In the mild group, the effect of SO₂ on the small airways was similar to that in the severe group, and it was negatively associated with large airway function. Exposure to CO and PM_2.5 was negatively associated with the large airway function of adults with asthma. The negative effects of SO₂ were more evident and widely observed in adults with severe and mild asthma than in adults with moderate asthma. Patients with asthma react differently to air pollutants as evidenced by their lung function levels.

Impact of Biologic Therapy on the Small Airways Asthma Phenotype

The small airways dysfunction (SAD) asthma phenotype is characterised by narrowing of airways < 2 mm in diameter between generations 8 and 23 of the bronchial tree. Recently, this has become particularly relevant as measurements of small airways using airway oscillometry for example, are strong determinants of asthma control and exacerbations in moderate-to-severe asthma. The small airways can be assessed using spirometry as forced expiratory flow rate between 25 and 75% of forced vital capacity (FEF_25-75) and has been deemed more accurate in detecting small airways dysfunction than forced expiratory volume in 1 s (FEV₁). Oscillometry as the heterogeneity in resistance between 5 and 20 Hz (R5-R20), low frequency reactance at 5 Hz (X5) or area under the reactance curve between 5 Hz and the resonant frequency can also be used to assess the small airways. The small airways can also be assessed using the multiple breath nitrogen washout (MBNW) test giving rise to values including functional residual capacity, lung clearance index and ventilation distribution heterogeneity in the conducting (Scond) and the acinar (Sacin) airways. The ATLANTIS group showed that the prevalence of small airways disease in asthma defined on FEF_25-75, oscillometry and MBNW all increased with progressive GINA asthma disease stages. As opposed to topical inhaler therapy that might not adequately penetrate the small airways, it is perhaps more intuitive that systemic anti-inflammatory therapy with biologics targeting downstream cytokines and upstream epithelial anti-alarmins may offer a promising solution to SAD. Here we therefore aim to appraise the available evidence for the effect of anti-IgE, anti-IL5 (Rα), anti-IL4Rα, anti-TSLP and anti-IL33 biologics on small airways disease in patients with severe asthma.

The predictive role of small airway dysfunction and airway inflammation biomarkers for asthma in preschool and school-age children: a study protocol for a prospective cohort study

BACKGROUND

Preschool children are at a high risk of developing asthma. Asthma in preschool children could remit in most cases, but could persist into school age, adolescence, or even adulthood in some cases. However, it is difficult to predict which children with preschool asthma will develop into school-age asthma. We present a cohort study protocol to explore the predictive role of small airway dysfunction and airway inflammation biomarkers of asthma in preschool and school-age children.

METHODS

A prospective cohort study will be conducted with at least 205 children with preschool asthma. All patients will be recruited when they consult a pediatric pulmonologist at the Children's Hospital of Chongqing Medical University and will be followed up to 6 years of age. Initially, patients' demographic information, medical history, physical findings, and questionnaire information will be collected, and baseline small airway function and inflammation biomarkers will be detected. During the follow-up period, medical history, physical findings, and the questionnaire results will be collected every 3 months, and small airway function will be tested by impulse oscillometry (IOS) every 6 months. At the final visit, a definite diagnosis of school-age asthma will be made by a pediatric pulmonologist based on the criteria of the Global Initiative for Asthma 2020.

DISCUSSION

The study will be the first to be conducted in preschool children assessing whether small airway dysfunction combined with airway eosinophilic biomarkers and club cell secretory protein is associated with school-age asthma. This study may provide new promising predictors of persistent asthma from preschool to school age.

TRIAL REGISTRATION

The study has been registered at the Chinese Clinical Trial Registry (ChiCTR2000039583). Registered on November 1, 2020. Protocol version: version 1.0, August 16, 2021.

Genetic deletion of the Tas2r143/Tas2r135/Tas2r126 cluster reveals that TAS2Rs may not mediate bitter tastant-induced bronchodilation

Bitter taste receptors (TAS2Rs) and their signaling elements are detected throughout the body, and bitter tastants induce a wide variety of biological responses in tissues and organs outside the mouth. However, the roles of TAS2Rs in these responses remain to be tested and established genetically. Here, we employed the CRISPR/Cas9 gene-editing technique to delete three bitter taste receptors-Tas2r143/Tas2r135/Tas2r126 (i.e., Tas2r triple knockout [TKO]) in mice. The fidelity and effectiveness of the Tas2r deletions were validated genetically at DNA and messenger RNA levels and functionally based on the tasting of TAS2R135 and TAS2R126 agonists. Bitter tastants are known to relax airways completely. However, TAS2R135 or TAS2R126 agonists either failed to induce relaxation of pre-contracted airways in wild-type mice and Tas2r TKO mice or relaxed them dose-dependently, but to the same extent in both types of mice. These results indicate that TAS2Rs are not required for bitter tastant-induced bronchodilation. The Tas2r TKO mice also provide a valuable model to resolve whether TAS2Rs mediate bitter tastant-induced responses in many other extraoral tissues.

Paramyxovirus replication induces the hexosamine biosynthetic pathway and mesenchymal transition via the IRE1α-XBP1s arm of the unfolded protein response

The paramyxoviridae, respiratory syncytial virus (RSV), and murine respirovirus are enveloped, negative-sense RNA viruses that are the etiological agents of vertebrate lower respiratory tract infections (LRTIs). We observed that RSV infection in human small airway epithelial cells induced accumulation of glycosylated proteins within the endoplasmic reticulum (ER), increased glutamine-fructose-6-phosphate transaminases (GFPT1/2) and accumulation of uridine diphosphate (UDP)-N-acetylglucosamine, indicating activation of the hexosamine biosynthetic pathway (HBP). RSV infection induces rapid formation of spliced X-box binding protein 1 (XBP1s) and processing of activating transcription factor 6 (ATF6). Using pathway selective inhibitors and shRNA silencing, we find that the inositol-requiring enzyme (IRE1α)-XBP1 arm of the unfolded protein response (UPR) is required not only for activation of the HBP, but also for expression of mesenchymal transition (EMT) through the Snail family transcriptional repressor 1 (SNAI1), extracellular matrix (ECM)-remodeling proteins fibronectin (FN1), and matrix metalloproteinase 9 (MMP9). Probing RSV-induced open chromatin domains by ChIP, we find XBP1 binds and recruits RNA polymerase II to the IL6, SNAI1, and MMP9 promoters and the intragenic superenhancer of glutamine-fructose-6-phosphate transaminase 2 (GFPT2). The UPR is sustained through RSV by an autoregulatory loop where XBP1 enhances Pol II binding to its own promoter. Similarly, we investigated the effects of murine respirovirus infection on its natural host (mouse). Murine respirovirus induces mucosal growth factor response, EMT, and the indicators of ECM remodeling in an IRE1α-dependent manner, which persists after viral clearance. These data suggest that IRE1α-XBP1s arm of the UPR pathway is responsible for paramyxovirus-induced metabolic adaptation and mucosal remodeling via EMT and ECM secretion.

Long-acting muscarinic antagonists and small airways in asthma: Which link?

Involvement of small airways, those of <2 mm in internal diameter, is present in all stages of asthma and contributes substantially to its pathophysiologic expression. Therefore, small airways are a potential target to achieve optimal asthma control. Airway tone, which is increased in asthma, is mainly controlled by the vagus nerve that releases acetylcholine (ACh) and activates muscarinic ACh receptors (mAChRs) post-synaptically on airway smooth muscle (ASM). In small airways, M₃ mAChRs are expressed, but there is no vagal innervation. Non-neuronal ACh released from the epithelial cells that may express choline acetyltransferase in response to inflammatory stimuli, as well as from other structural cells in the airways, including fibroblasts and mast cells, can activate mAChRs. By antagonizing M₃ mAChR, the contraction of the ASM is prevented and, potentially, local inflammation can be reduced and the progression of remodeling may be averted. In fact, ACh also contributes to inflammation and remodeling of the airways and regulates the growth of ASM. Several experimental studies have demonstrated the potential benefit derived from the use of mAChR antagonists, mainly long-acting mAChR antagonists (LAMAs), on small airways in asthma. However, there are several confounding factors that may cause a wrong estimation of the relationship between LAMAs and small airways in asthma. Further studies are needed to differentiate broncholytic and anti-inflammatory effects of LAMAs and to better understand the interaction between LAMAs and corticosteroids, also in the context of a triple therapy that includes a β₂ -AR agonist, at different levels of the bronchial tree.

Small airways in asthma: from bench-to-bedside

INTRODUCTION

Historically, asthma was considered a disease predominantly of the large airways, but gradually small airways have been recognized as the major site of airflow obstruction. Small airway dysfunction (SAD) significantly contributes to the pathophysiology of asthma and it is present across all asthma severities. Promising pre-clinical findings documented enhanced beneficial effects of combination therapies on small airways compared to monocomponents, thus it was questioned whether this could translate into further clinical implications from bench-to-bedside. The aim of this review was to systematically assess the state of the art of small airway involvement in asthma, especially in response to different pharmacological treatments acting on the respiratory system.

EVIDENCE ACQUISITION

A comprehensive literature search was performed in MEDLINE for randomized controlled trials (RCTs) characterizing the impact on small airways of different pharmacological treatments acting on the respiratory system. The results were extracted and reported via qualitative synthesis.

EVIDENCE SYNTHESIS

Overall, 63 studies were identified from the literature search, whereas 23 RCTs met the inclusion criteria. Evidence confirms that both drug particle size and the type of inhalation devices represent two of the most important variables for an effective peripheral lung distribution.

CONCLUSIONS

Despite the numerous methodological tools to detect SAD, there is still no gold standard diagnostic method to assess small airways, especially in severe asthma. Further research should be directed to improve primary and secondary prevention strategies by supporting the combined approach of different non-invasive techniques for an early detection of peripheral abnormalities and optimization of asthma therapy.

ERS/EAACI statement on severe exacerbations in asthma in adults: facts, priorities and key research questions

Despite the use of effective medications to control asthma, severe exacerbations in asthma are still a major health risk and require urgent action on the part of the patient and physician to prevent serious outcomes such as hospitalisation or death. Moreover, severe exacerbations are associated with substantial healthcare costs and psychological burden, including anxiety and fear for patients and their families. The European Academy of Allergy and Clinical Immunology (EAACI) and the European Respiratory Society (ERS) set up a task force to search for a clear definition of severe exacerbations, and to also define research questions and priorities. The statement includes comments from patients who were members of the task force.

Asthma Diagnosis: The Changing Face of Guidelines

Asthma, the most common chronic respiratory disease, is frequently misdiagnosed, and accounts for a significant proportion of healthcare expenditure. This has driven the National Institute for Health and Care Excellence (NICE) in the United Kingdom (UK) to produce recent guidance; in places, this contrasts to that of the British Thoracic Society/Scottish Intercollegiate Guideline Network (BTS/SIGN), which have been producing their own guidance since 2003. Here we review the history of asthma diagnostic guidelines, and compare and review the evidence behind them, in adults and in children. We discuss the definitions of asthma and how these drive the concepts behind diagnostic strategies. We anticipate future directions in asthma diagnosis which will take into account the concepts of personalised medicine and disease endotypes. We also consider the utility of tests in use now and in the future, in particular novel tests relating to small airway inflammation and obstruction.

Efficacy of ciclesonide in the treatment of patients with asthma exacerbation

Introduction

Progressing deterioration of the lung function, dyspnoea, cough, wheezing and chest tightness are the main features of asthma exacerbations. The first step in the prevention of severe asthma exacerbations is to intensify the anti-inflammatory treatment with high doses of inhaled corticosteroids (ICS).

Aim

To assess the efficacy of ciclesonide in patients who have been losing control of asthma despite being treated with medium doses of inhaled corticosteroids and long-acting β₂-agonists (LABA) as the second controller.

Material and methods

The study was conducted in a group of 74 asthmatic patients who have been losing control of their asthma. Subjects entering the study received the following anti-inflammatory interventions: high doses of ciclesonide (1280 μg) or 640 μg of ciclesonide added to a current dose of ICS or a doubled dose of current ICS.

Results

Treatment options containing ciclesonide have shown statistically and clinically important advantages (improvement of Asthma Control Test score, reduction in rescue medication consumption, reduction in day and night symptoms score, improvement in spirometry parameters, decrease in exhaled nitric oxide, and no necessity of oral corticosteroids treatment) in comparison to patients for whom medium doses of the previously used inhaled corticosteroid were doubled.

Conclusions

Treating with high doses of ciclesonide is characterised by a quick and potent anti-inflammatory effect as well as prompt clinical improvement along with the proper safety profile in patients experiencing asthma exacerbations.

The effects of endoscopic sinus surgery on pulmonary function in chronic rhinosinusitis patients with asthma: a systematic review and meta-analysis

PURPOSE

Evidences showed improvements in clinical asthma outcomes following endoscopic sinus surgery (ESS) in chronic rhinosinusitis (CRS) patients with asthma. However, pulmonary function benefits have remained controversial up to date. The goal of this study was to conduct a systematic review and meta-analysis to investigate the effects of ESS on pulmonary function tests in CRS patients with asthma.

METHODS

Pubmed, Embase and Cochrane Library were searched up to March 2018 to obtain relevant studies. The researches that evaluated the effects of ESS on pulmonary function in CRS patients with asthma and had at least one parameter of pulmonary function tests before and after surgery were included in the study.

RESULTS

A total of 13 studies containing 421 patients satisfied the eligibility after judgment by 2 reviewers. These included three RCTs and ten case series. The heterogeneity in parameters of spirometry and difference in data presented forms across studies along with the lack of standard deviation of some data make it difficult to synthesize results. If data were unavailable for meta-analyses, descriptive statistics were used to report study outcomes. After qualitative and quantitative analysis, the weighted mean change after ESS in forced expiratory flow between 25% and 75% of vital capacity (FEF25-75%) was 0.21 L/s (95% CI 0.12-0.30); eight of ten studies supported that forced expiratory volume at 1 s (FEV1) improved after ESS; five of six studies supported that peak expiratory flow (PEF) improved after ESS. However, strength of evidence is generally low to insufficient.

CONCLUSION

A generally low-quality evidence supports the association between ESS and improvements in FEF25-75%, FEV1 and PEF. A few studies met inclusion criteria for meta-analysis, which indicates the need for more high-quality studies to determine the effect of ESS.

The Role of Airway Inflammation and Bronchial Hyperresponsiveness in Athlete's Asthma

PURPOSE

Asthma is frequently reported in endurance athletes. The aim of the present study was to assess the long-term airway inflammatory response to endurance exercise in high-level athletes with and without asthma.

METHODS

In a cross-sectional design, 20 asthmatic athletes (10 swimmers and 10 cross-country skiers), 19 athletes without asthma (10 swimmers and 9 cross-country skiers), and 24 healthy nonathletes completed methacholine bronchial challenge, lung function tests, and sputum induction on two separate days. All athletes competed on a national or international level and exercised ≥10 h·wk. The nonathletes exercised ≤5 h·wk and reported no previous lung disease. Bronchial hyperresponsiveness (BHR) was defined as a methacholine provocation dose causing 20% decrease in the forced expiratory volume in 1 s of ≤8 μmol.

RESULTS

BHR was present in 13 asthmatic athletes (62%), 11 healthy athletes (58%), and 8 healthy nonathletes (32%), and the prevalence differed among groups (P = 0.005). Sputum inflammatory and epithelial cell counts did not differ between groups and were within the normal range. Median (25th to 75th percentiles) sputum interleukin-8 was elevated in both asthmatic (378.4 [167.0-1123.4]) and healthy (340.2 [175.5-892.4]) athletes as compared with healthy nonathletes (216.6 [129.5-314.0], P = 0.02). No correlations were found between provocation dose causing 20% decrease and sputum cell counts.

CONCLUSION

Independent of asthma diagnosis, a high occurrence of BHR and an increased sputum interleukin-8 were found in athletes as compared with nonathletes. Airway inflammation or epithelial damage was not related to BHR.

Impulse oscillometry and nitrogen washout test in the assessment of small airway dysfunction in asthma: Correlation with quantitative computed tomography

OBJECTIVE

Small airway dysfunction (SAD) and airway remodeling influence the disease control and progression in asthma. We investigated whether impulse oscillometry (IOS) and single breath nitrogen washout (SBN₂W) could be reliable tests in evaluating SAD and airway remodeling by correlating their data with radiological parameters derived from quantitative chest multidetector computed tomography (MDCT) imaging.

METHODS

Lung function tests were performed before and after bronchodilator. The MDCT lung scans were acquired at full inspiration and expiration using a portable spirometer to control the respiratory manoeuvres. Symptom control was assessed using the Asthma Control Test (ACT) questionnaire.

RESULTS

Twenty six patients were enrolled. The bronchial lumen area (LA) measured with MDCT lung scan, correlated inversely with airway resistance (Raw, p < 0.001) and with total and large airway oscillometric resistance (R5, p = 0.002 and R20, p = 0.006, respectively). However these two last correlations became non-significant after Bonferroni correction for multiple comparisons. The radiological quantification of air trapping correlated with Raw (p < 0.001), residual volume (RV, p < 0.001), and the slope of phase III of SBN₂W (DeltaN₂, p < 0.001) whereas the correlation with small airway oscillometric resistance (R5-20) was non-significant after Bonferroni adjustment. Finally, air trapping was significantly higher in patients with a fixed bronchial obstruction in comparison to patients with reversible obstruction.

CONCLUSIONS

Plethysmographic method remains the main tool to investigate SAD and airway remodeling in asthmatic patients. The integration with the SBN₂W test proved useful to better evaluate the small airway involvement whereas IOS showed a weaker correlation with both radiological and clinical data.

Lung responses in murine models of experimental asthma: Value of house dust mite over ovalbumin sensitization

Ovalbumin (OVA) sensitization has limitations in modelling asthma. Thus, we examined the value of allergic sensitization using a purified natural allergen, house dust mite (HDM), over the sensitization performed with OVA. Mice were sham-treated, or sensitized with OVA- or HDM with identical chronology. Airway resistance, tissue damping and elastance were assessed under control conditions and after challenging the animals with methacholine (MCh) and the specific allergen. Inflammatory profile of the bronchoalveolar lavage fluid was characterized and lung histology was performed. While no difference in the lung responsiveness to the specific allergen was noted, hyperresponsiveness to MCh was observed only in the HDM-sensitized animals in the lung peripheral parameters. Lung inflammation differed between the models, but excessive bronchial smooth muscle remodelling occurred only with OVA. In conclusion, we demonstrate that a purified natural allergen offers a more relevant murine model of human allergic asthma by expressing the key features of this chronic inflammatory disease both in the lung function and structure.

[Application of pulmonary function and fractional exhaled nitric oxide tests in the standardized management of bronchial asthma in children]

OBJECTIVE

To investigate the changes of pulmonary function and fractional exhaled nitric oxide (FeNO) in the standardized treatment of bronchial asthma in children.

METHODS

A total of 254 children who were newly diagnosed with acute exacerbation of bronchial asthma were selected as asthma group, and they were divided into two subgroups: asthma with concurrent rhinitis and asthma without concurrent rhinitis. All patients received the standardized management and treatment for one year. The pulmonary function parameters included forced expiratory volume in one second (FEV1), peak expiratory flow (PEF), maximal mid-expiratory flow (MMEF), and mid-expiratory flow at 25%, 50%, and 75% of vital capacity (MEF25, MEF50, and MEF75). The FeNO levels were measured before treatment and at 3, 6, 9, and 12 months after treatment. Another 62 healthy children were selected as the control group, and the pulmonary function and FeNO levels were measured only once.

RESULTS

During one year of standardized treatment, FEV1, PEF, MMEF, MEF25, MEF50, and MEF75 gradually increased, and FeNO levels gradually decreased (P<0.05). Indicators of large airway function, such as FEV1 and PEF, almost returned to normal after 6 months of treatment; indicators of small airway function, such as MMEF, MEF25, MEF50, and MEF75 almost returned to normal after 9 months of treatment; there were no significant differences in the above indices between the asthma group and the control group after one year of treatment (P>0.05). However, the asthma group had a significantly higher FeNO levels than the control group after one year of treatment (P<0.05). The asthmatic patients with concurrent rhinitis had significantly higher FeNO levels than those without concurrent rhinitis before treatment and 3 months after treatment (P<0.05). Before treatment, there was a significant negative correlation between FeNO levels and pulmonary function parameters (P<0.05).

CONCLUSIONS

With the standardized treatment of bronchial asthma in children, pulmonary function parameters gradually increase and FeNO levels gradually decrease. The recovery of large airway function occurs earlier than the recovery of small airway function. Furthermore, the effect of rhinitis on airway responsiveness should be noted.

Maximal mid-expiratory flow detects early lung disease in α1-antitrypsin deficiency

Pathological studies suggest that loss of small airways precedes airflow obstruction and emphysema in chronic obstructive pulmonary disease (COPD). Not all α₁-antitrypsin deficiency (AATD) patients develop COPD, and measures of small airways function might be able to detect those at risk.Maximal mid-expiratory flow (MMEF), forced expiratory volume in 1 s (FEV₁), ratio of FEV₁/forced vital capacity (FVC), health status, presence of emphysema (computed tomography (CT) densitometry) and subsequent decline in FEV₁ were assessed in 196 AATD patients.FEV₁/FVC, FEV₁ % predicted and lung densitometry related to MMEF % pred (r²=0.778, p<0.0001; r²=0.787, p<0.0001; r²=0.594, p<0.0001, respectively) in a curvilinear fashion. Patients could be divided into those with normal FEV₁/FVC and MMEF (group 1), normal FEV₁/FVC and reduced MMEF (group 2) and those with spirometrically defined COPD (group 3). Patients in group 2 had worse health status than group 1 (median total St George's Respiratory Questionnaire (SGRQ) 23.15 (interquartile range (IQR) 7.09-39.63) versus 9.67 (IQR 1.83-22.35); p=0.006) and had a greater subsequent decline in FEV₁ (median change in FEV₁ -1.09% pred per year (IQR -1.91-0.04% pred per year) versus -0.04% pred per year (IQR -0.67-0.03% pred per year); p=0.007).A reduction in MMEF is an early feature of lung disease in AATD and is associated with impaired health status and a faster decline in FEV₁.

Can the response to Omalizumab be influenced by treatment duration? A real-life study

OBJECTIVE

It is unknown whether Omalizumab effectiveness changes over the course of time. Our retrospective real-life study tried to analyze whether Omalizumab response may be influenced by treatment duration.

METHODS

340 severe asthmatics treated with Omalizumab for different periods of time were recruited. They were subdivided into 4 groups according to the Omalizumab treatment length: <12, between 12 and 24, between 24 and 60 and >60 months. Omalizumab treatment results (FEV₁, exacerbations, ACT, SABA use, asthma control levels, medications used e and ICS doses) were compared.

RESULTS

ACT, exacerbations, GINA control levels, ICS doses and SABA use were similar in all groups with different Omalizumab treatment durations. Using a linear regression model, corrected for all confounding variables, a higher significant positive increase in FEV₁% in subjects treated for 12-24 (β = 9.49; p = 0.034) or 24-60 months (β = 8.56; p = 0.043) was found when compared with subjects treated for a shorter period. Treatment duration was positively associated with a step down of the other associated therapies (OR: 1.013; p = 0.019). This association was more relevant (OR: 4.167; p = 0.005) when we considered Omalizumab treatment duration >60 months compared to the shorter therapy. In particular, the percentage of subjects that were taking Montelukast, LABAs and oral corticosteroids was lower in the group treated with Omalizumab for a longer period of time.

CONCLUSION

In real-life, the positive Omalizumab response remained stable for over 60 months. Long term Omalizumab treatment may lead to a discontinuation of some associated medications and to a slowing down of FEV₁ decline.

CysLT2 receptor activation is involved in LTC4-induced lung air-trapping in guinea pigs

CysLT₁ receptors are known to be involved in the pathogenesis of asthma. However, the functional roles of CysLT₂ receptors in this condition have not been determined. The purpose of this study is to develop an experimental model of CysLT₂ receptor-mediated LTC₄-induced lung air-trapping in guinea pigs and use this model to clarify the mechanism underlying response to such trapping. Because LTC₄ is rapidly converted to LTD₄ by γ-glutamyltranspeptidase (γ-GTP) under physiological conditions, S-hexyl GSH was used as a γ-GTP inhibitor. In anesthetized artificially ventilated guinea pigs with no S-hexyl GSH treatment, i.v. LTC₄-induced bronchoconstriction was almost completely inhibited by montelukast, a CysLT₁ receptor antagonist, but not by BayCysLT₂RA, a CysLT₂ receptor antagonist. The inhibitory effect of montelukast was diminished by treatment with S-hexyl GSH, whereas the effect of BayCysLT₂RA was enhanced with increasing dose of S-hexyl GSH. Macroscopic and histological examination of lung tissue isolated from LTC₄-/S-hexyl-GSH-treated guinea pigs revealed air-trapping expansion, particularly at the alveolar site. Inhaled LTC₄ in conscious guinea pigs treated with S-hexyl GSH increased both airway resistance and airway hyperinflation. On the other hand, LTC₄-induced air-trapping was only partially suppressed by treatment with the bronchodilator salmeterol. Although montelukast inhibition of LTC₄-induced air-trapping was weak, treatment with BayCysLT₂RA resulted in complete suppression of this air-trapping. Furthermore, BayCysLT₂RA completely suppressed LTC₄-induced airway vascular hyperpermeability. In conclusion, we found in this study that CysLT₂ receptors mediate LTC₄-induced bronchoconstriction and air-trapping in S-hexyl GSH-treated guinea pigs. It is therefore believed that CysLT₂ receptors contribute to asthmatic response involving air-trapping.

Study on small airway function in asthmatics with fractional exhaled nitric oxide and impulse oscillometry

OBJECTIVES

The invasive techniques can be direct and objective to assess small airway function, but they have significant risks and inconveniences for patients and cannot be repeated often. Some sophisticated techniques such as fractional exhaled nitric oxide (FeNO) and impulse oscillometry (IOS) may surmount such restrictions. Therefore, we investigated the relation among FeNO, IOS, and small airway function in asthmatic patients.

METHODS

We recruited 140 asthmatic patients including 69 patients with small airway normal function and 71 patients with small airway dysfunction. FeNO, eosinophil（EOS）count and total immunoglobulin E (IgE) in peripheral blood, pulmonary function, as well as IOS were measured.

RESULTS

The levels of FeNO, the reactance area (AX), the resonant frequency Fres and EOS were significantly increased in small airway dysfunction group compared with small airway normal function group (P < 0.01 respectively). A multiple regression model showed that FeNO, AX and Fres were correlative factors of mid forced expiratory flow of percentages of predicted values [FEF25-75 (%pred)] (P < 0.01, respectively). A receiver operating characteristic (ROC) analysis showed that the combination of FeNO, AX and Fres had a greater area under the ROC curve (AUC) than each of them (AUC: 0.881, P < .001, 95％CI: 0.815-0.929).

CONCLUSION

FeNO and IOS are helpful in diagnosis of small airway dysfunction with high sensitivity and specificity, and FeNO combined with IOS can better evaluate the small airway function in asthmatic patients.

Inhaled beclometasone dipropionate/formoterol fumarate extrafine fixed combination for the treatment of asthma

Inhaled therapy is often considered the cornerstone of asthma management and international guidelines recommend combination therapy of inhaled corticosteroids (ICS) and long-acting-beta2-agonists (LABA) in a large proportion of asthmatic patients. The effectiveness of ICS/LABA is dependent on the correct choice of device and proper inhalation technique, this influences drug delivery and distribution along the bronchial tree, including the most peripheral airways. The fixed combination of beclometasone dipropionate/formoterol fumarate (BDP/FF) is the only extrafine formulation available in pressurized metered dose inhaler (pMDI) and in dry powder inhaler (DPI). Here, we focus on the recent significant advances regarding BDP/FF fixed combination for the treatment of asthma.

Early growth characteristics and the risk of reduced lung function and asthma: A meta-analysis of 25,000 children

BACKGROUND

Children born preterm or with a small size for gestational age are at increased risk for childhood asthma.

OBJECTIVE

We sought to assess the hypothesis that these associations are explained by reduced airway patency.

METHODS

We used individual participant data of 24,938 children from 24 birth cohorts to examine and meta-analyze the associations of gestational age, size for gestational age, and infant weight gain with childhood lung function and asthma (age range, 3.9-19.1 years). Second, we explored whether these lung function outcomes mediated the associations of early growth characteristics with childhood asthma.

RESULTS

Children born with a younger gestational age had a lower FEV1, FEV1/forced vital capacity (FVC) ratio, and forced expiratory volume after exhaling 75% of vital capacity (FEF75), whereas those born with a smaller size for gestational age at birth had a lower FEV1 but higher FEV1/FVC ratio (P < .05). Greater infant weight gain was associated with higher FEV1 but lower FEV1/FVC ratio and FEF75 in childhood (P < .05). All associations were present across the full range and independent of other early-life growth characteristics. Preterm birth, low birth weight, and greater infant weight gain were associated with an increased risk of childhood asthma (pooled odds ratio, 1.34 [95% CI, 1.15-1.57], 1.32 [95% CI, 1.07-1.62], and 1.27 [95% CI, 1.21-1.34], respectively). Mediation analyses suggested that FEV1, FEV1/FVC ratio, and FEF75 might explain 7% (95% CI, 2% to 10%) to 45% (95% CI, 15% to 81%) of the associations between early growth characteristics and asthma.

CONCLUSIONS

Younger gestational age, smaller size for gestational age, and greater infant weight gain were across the full ranges associated with childhood lung function. These associations explain the risk of childhood asthma to a substantial extent.

Maintaining Control of Chronic Obstructive Airway Disease: Adherence to Inhaled Therapy and Risks and Benefits of Switching Devices

Asthma and chronic obstructive pulmonary disease (COPD) are major obstructive airway diseases that involve underlying airway inflammation. The most widely used pharmacotherapies for asthma and COPD are inhaled agents that have been shown to be effective and safe in these patients. However, despite the availability of effective pharmacologic treatment and comprehensive treatment guidelines, the prevalence of inadequately controlled asthma and COPD is high. A main reason for this is poor adherence. Adherence is a big problem for all chronic diseases, but in asthma and COPD patients there are some additional difficulties because of poor inhalation technique and inhaler choice. Easier-to-use devices and educational strategies on proper inhaler use from health caregivers can improve inhaler technique. The type of device used and the concordance between patient and physician in the choice of inhaler can also improve adherence and are as important as the drug. Adherence to inhaled therapy is absolutely necessary for optimizing patient control. If disease control is not adequate despite good adherence, switching to a more appropriate inhaled therapy is recommended. By contrast, uninformed switching or switching to less user-friendly inhaler may impact disease control negatively. This critical review of the available literature is aimed to provide a guidance protocol on when a switch may be recommended in individual patients.

Asthma

Asthma is the most common inflammatory disease of the lungs. The prevalence of asthma is increasing in many parts of the world that have adopted aspects of the Western lifestyle, and the disease poses a substantial global health and economic burden. Asthma involves both the large-conducting and the small-conducting airways, and is characterized by a combination of inflammation and structural remodelling that might begin in utero. Disease progression occurs in the context of a developmental background in which the postnatal acquisition of asthma is strongly linked with allergic sensitization. Most asthma cases follow a variable course, involving viral-induced wheezing and allergen sensitization, that is associated with various underlying mechanisms (or endotypes) that can differ between individuals. Each set of endotypes, in turn, produces specific asthma characteristics that evolve across the lifecourse of the patient. Strong genetic and environmental drivers of asthma interconnect through novel epigenetic mechanisms that operate prenatally and throughout childhood. Asthma can spontaneously remit or begin de novo in adulthood, and the factors that lead to the emergence and regression of asthma, irrespective of age, are poorly understood. Nonetheless, there is mounting evidence that supports a primary role for structural changes in the airways with asthma acquisition, on which altered innate immune mechanisms and microbiota interactions are superimposed. On the basis of the identification of new causative pathways, the subphenotyping of asthma across the lifecourse of patients is paving the way for more-personalized and precise pathway-specific approaches for the prevention and treatment of asthma, creating the real possibility of total prevention and cure for this chronic inflammatory disease.

Airway hyper-responsiveness and small airway function in children with well-controlled asthma

BACKGROUND

Airway hyper-responsiveness (AHR) and small airway function are critical to children with asthma. Little is known about the role of the small airway in well-controlled subjects with AHR. We aimed to evaluate AHR and small airway function in children with well-controlled asthma, and to investigate the association between them.

METHODS

We studied 116 cases of children with well-controlled asthma (group A), 46 cases healthy children as controls (group C). Spirometry, impulse oscillometry (IOS), and methacholine challenge test (MCT) were conducted on all the children.

RESULTS

(i) Group A and group C had no differences in forced expiratory volume in 1 s (FEV1) and FEV1/forced vital capacity (FVC) ratio (P > 0.05). Forced expiratory flow between 25 and 75% of vital capacity (FEF25-75) and reactance at 5 Hz (X5) in group A were significantly lower than those in group C. (ii) One hundred and five cases (90.5%) of group A proved positive to MCT. (iii) FEF25-75 in group A proved positive to MCT but were lower than those proved negative (P < 0.05).

CONCLUSION

AHR persisted in majority of children with well-controlled asthma. Among children with well-controlled asthma, small airway function was lower in those with AHR than those without AHR.

Bronchial thermoplasty: reappraising the evidence (or lack thereof)

Bronchial thermoplasty (BT) involves the application of radiofrequency energy to visible proximal airways to selectively ablate airway smooth muscle. BT is the first nonpharmacologic interventional therapy approved by the US Food and Drug Administration (FDA) for severe asthma. This approval was based on the results of the pivotal Asthma Intervention Research (AIR)-2 trial, which is the only randomized, double-blind, sham-controlled trial of BT. The primary end point of the AIR-2 trial was improvement in the Asthma Quality of Life Questionnaire (AQLQ). The results of the AIR-2 trial have generated enormous interest, controversy, and confusion regarding the true efficacy of BT for severe asthma. Current marketing of BT highlights its use for patients with "severe" asthma, which is interpreted by most practicing clinicians as meaning oral corticosteroid dependence, frequent exacerbations, or a significantly reduced FEV1 with a poor quality of life. Did the AIR-2 trial include patients with a low FEV1, oral steroid dependence, or frequent exacerbations? Did the trial show efficacy for any of the primary or secondary end points? The FDA approved the device based on the reduction in severe asthma exacerbations. However, were the rates of asthma exacerbations, ED visits, or hospitalizations truly different between the two groups, and was this type of analysis even justified given the original study design? This commentary is designed to specifically answer these questions and help the practicing clinician navigate the thermoplasty literature with confidence and clarity. We carefully dissect the design, conduct, and results of the AIR-2 trial and raise serious questions about the efficacy of bronchial thermoplasty.