Radiofrequency ablation of airway smooth muscle for sustained treatment of asthma: preliminary investigations

Effect of bronchial thermoplasty on static and dynamic lung compliance and resistance in patients with severe persistent asthma

RATIONALE

Bronchial thermoplasty (BT) reduces severity and frequency of bronchoconstriction and symptoms in severe, persistent asthmatics although it is usually not associated with change in spirometric variables. Other than spirometry. there are almost no data on changes in lung mechanics following BT.

OBJECTIVE

To assess lung static and dynamic lung compliance (Cst,L and Cdyn,L, respectively) and static and dynamic lung resistance (Rst,L and Rdyn,L, respectively) before and after BT in severe asthmatics using the esophageal balloon technique.

METHODS

Rdyn,L and Cdyn,L were measured at respiratory frequencies up to 145 breaths/min, using the esophageal balloon technique in 7 patients immediately before and 12-50 weeks after completing a series of 3 BT sessions.

RESULTS

All patients experienced improved symptoms within a few weeks following completion of BT. Pre-BT, all patients exhibited frequency dependency of lung compliance, with mean Cdyn,L decreasing to 63% of Cst,L at maximum respiratory rates. Post-BT, Cst,L did not change significantly from pre-thermoplasty values, while Cdyn,L diminished to 62%% of Cst,L. In 4 of 7 patients, post-BT values of Cdyn,L were consistently higher than pre-BT over the range of respiratory rates. RL in 4 of 7 patients during quiet breathing and at higher respiratory frequencies decreased following BT.

CONCLUSIONS

Patients with severe persistent asthma exhibit increased resting lung resistance and frequency dependence of compliance, the magnitudes of which are ameliorated in some patients following bronchial thermoplasty and associated with variable change in frequency dependence of lung resistance. These findings are related to asthma severity and may be related to the heterogeneous and variable nature of airway smooth muscle modeling and its response to BT.

Endobronchial Ultrasound is Useful in the Assessment of Bronchial Wall Changes Related to Bronchial Thermoplasty

Background

Bronchial thermoplasty (BT) is an interventional endoscopic treatment for severe asthma leading to the clinical improvement, but morphologic changes of bronchial wall related to the procedure and predictors of a favorable response to BT remain uncertain. The aim of the study was to validate an endobronchial ultrasound (EBUS) in assessing the effectiveness of BT treatment.

Methods

Patients with severe asthma who met the clinical criteria for BT were included. In all patients clinical data, ACT and AQLQ questionnaires, laboratory tests, pulmonary function tests and bronchoscopy with radial probe EBUS and bronchial biopsies were collected. BT was performed in patients with the thickest bronchial wall L₂ layer representing ASM. These patients were evaluated before and after 12 months of follow-up. The relationship between baseline parameters and clinical response was explored.

Results

Forty patients with severe asthma were enrolled to the study. All 11 patients qualified to BT successfully completed the 3 sessions of bronchoscopy. BT improved asthma control (P=0.006), quality of life (P=0.028) and decreased exacerbation rate (P=0.005). Eight of the 11 patients (72.7%) showed a clinically meaningful improvement. BT also led to a significant decrease in the thicknesses of bronchial wall layers in EBUS (L₁ decreased from 0.183 to 0.173 mm, P=0.003; L₂ from 0.207 to 0.185 mm, P = 0.003; and L_3-5 from 0.969 to 0.886 mm, P=0.003). Median ASM mass decreased by 61.8% (P=0.002). However, there was no association between baseline patient characteristics and the magnitude of clinical improvement after BT.

Conclusion

BT was associated with a significant decrease in the thickness of the bronchial wall layers measured by EBUS including L₂ layer representing ASM and ASM mass reduction in bronchial biopsy. EBUS can assess bronchial structural changes related to BT; however, it did not predict the favorable clinical response to therapy.

Historical eye: from traditional to endobronchial ultrasound-guided needle aspiration and beyond

PURPOSE OF REVIEW

In the history of bronchoscopy, the advent of flexible transbronchial needle aspiration (TBNA) before and, subsequently, of endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA), have represented fundamental events, as they have significantly and definitively changed interventional pulmonology's role in diagnostic and therapeutic work-up of most of thoracic diseases.Purpose of this historical review is to retrace the main stages that have contributed to the development of these two techniques.

RECENT FINDINGS

TBNA allowed the bronchoscopists to overcome the barrier of the tracheobronchial wall and to obtain samples from hilar-mediastinal lesions. With this additional method, bronchoscopy has become an essential procedure for staging of lung cancer.The advent of echo-bronchoscopes, allowing to perform TBNA under direct ultrasound guidance in real time, further increased the diagnostic yield of this technique. Furthermore, the insertion of the echo-bronchoscope through the oesophagus allowed to extend the landscape of targets to sample, including also para-esophageal lesions, liver metastases, celiac nodes and left adrenal glands.EBUS-TBNA has shown its usefulness not only in the approach to mediastinal lesions, but also in other clinical conditions, such as lung nodules or masses adjacent to the tracheobronchial tree.

SUMMARY

Despite the obvious advantages of EBUS-TBNA, this technology is not yet available in many centres and countries worldwide. For this reason, TBNA remains a basic technique that must complete the technical background of bronchoscopists and it should not be forgotten.

Which Endoscopic Procedure to Use and in What Patient? Valves, Coils, Foam, and Heat in COPD and Asthma

Despite the latest developments in therapeutic agents targeting airway endotypes, a significant proportion of patients with asthma and chronic obstructive pulmonary disease (COPD) remain symptomatic. Endoscopic therapies have a complementary role in the management of these airway diseases. The sustained efficacy of bronchial thermoplasty (BT) among patients with asthma over 10 years has been encouraging, as it has been shown to improve symptom control and reduce hospital admissions and exacerbations. Studies suggest that BT helps ameliorate airway inflammation and reduce airway smooth muscle thickness. While studies suggest that it is as effective as biologic agents, its role in the management of severe asthma has yet to be clearly defined and GINA 2022 still suggests limiting its use to patients with characteristics of the various populations studied. Conversely, bronchoscopic lung volume reduction has shown promise among patients with advanced COPD. Rigorous patient selection is important. Patients with minimal collateral ventilation (CV) and higher heterogeneity index have shown to benefit the most from endobronchial valve (EBV) therapy. For those with ongoing CV, endobronchial coils would be more appropriate. Both therapeutic modalities have demonstrated improved quality of life, effort tolerance, and lung function indices among appropriately selected patients. The emerging evidence suggests that endoscopic procedures among airway disease still have a substantial role to play despite the development of new therapeutic options.

Endoscopic Options for Moderate COPD, Chronic Bronchitis, and Uncontrolled Asthma

Until now, interventional therapies for patients with chronic obstructive pulmonary disease have been available in the form of lung volume reduction procedures as end-stage options. Currently, the range of indications is expanding to include earlier stages of the diseases. Lung denervation is available for moderate COPD, and patients with chronic bronchitis are being evaluated for endoscopic goblet cell ablation. Rheoplasty, metered spray cryo technique, and Karakoca resector balloon are used for this indication. But also, for patients with severe uncontrolled asthma, several techniques are available today. In addition to thermoplasty as a long-proven procedure, new and currently under investigation is the targeted lung denervation.Most of these techniques are currently being tested in large pivotal trials and it will soon become clear in which phenotype which technique will be used in the different forms and stages of obstructive diseases. The current paper presents the techniques and the currently available literature.

Pulmonary functional MRI: Detecting the structure-function pathologies that drive asthma symptoms and quality of life

Pulmonary functional MRI (PfMRI) using inhaled hyperpolarized, radiation-free gases (such as ³ He and ¹²⁹ Xe) provides a way to directly visualize inhaled gas distribution and ventilation defects (or ventilation heterogeneity) in real time with high spatial (~mm³ ) resolution. Both gases enable quantitative measurement of terminal airway morphology, while ¹²⁹ Xe uniquely enables imaging the transfer of inhaled gas across the alveolar-capillary tissue barrier to the red blood cells. In patients with asthma, PfMRI abnormalities have been shown to reflect airway smooth muscle dysfunction, airway inflammation and remodelling, luminal occlusions and airway pruning. The method is rapid (8-15 s), cost-effective (~$300/scan) and very well tolerated in patients, even in those who are very young or very ill, because unlike computed tomography (CT), positron emission tomography and single-photon emission CT, there is no ionizing radiation and the examination takes only a few seconds. However, PfMRI is not without limitations, which include the requirement of complex image analysis, specialized equipment and additional training and quality control. We provide an overview of the three main applications of hyperpolarized noble gas MRI in asthma research including: (1) inhaled gas distribution or ventilation imaging, (2) alveolar microstructure and finally (3) gas transfer into the alveolar-capillary tissue space and from the tissue barrier into red blood cells in the pulmonary microvasculature. We highlight the evidence that supports a deeper understanding of the mechanisms of asthma worsening over time and the pathologies responsible for symptoms and disease control. We conclude with a summary of approaches that have the potential for integration into clinical workflows and that may be used to guide personalized treatment planning.

Bronchial thermoplasty guided by hyperpolarised gas magnetic resonance imaging in adults with severe asthma: a 1-year pilot randomised trial

Patient-specific localisation of ventilation defects using hyperpolarised gas magnetic resonance imaging (MRI) introduces the possibility of regionally targeted bronchial thermoplasty (BT) for the treatment of severe asthma. We aimed to demonstrate that BT guided by MRI to ventilation defects reduces the number of radiofrequency activations while resulting in improved asthma quality-of-life and control scores that are non-inferior to standard BT. In a 1-year pilot randomised controlled trial, 14 patients with severe asthma who were clinically eligible to receive BT underwent hyperpolarised gas MRI to characterise ventilation defects and were randomised to MRI-guided or standard BT. End-points were improved Asthma Quality of Life Questionnaire (AQLQ) and Asthma Control Questionnaire (ACQ) scores, the proportion of AQLQ and ACQ responders and the number of radiofrequency activations and bronchoscopy sessions. Participants who underwent MRI-guided BT received 53% fewer radiofrequency activations than those who had standard BT (p=0.003). At 12 months, the mean improvement from baseline was similar between the MRI-guided group (n=5) and the standard group (n=7) for AQLQ score (MRI-guided: 1.8, 95% CI 0.1-3.5, p=0.04; standard: 0.7, 95% CI -0.9-2.3, p=0.30) (p=0.25) and ACQ-5 score (MRI-guided: -1.4, 95% CI -2.6- -0.2, p=0.03; standard: -0.7, 95% CI -1.3-0.0, p=0.04) (p=0.17). A similar proportion of participants in both groups achieved a clinically relevant improvement in AQLQ score (MRI-guided: 80%; standard: 71%) and ACQ-5 score (MRI-guided: 80%; standard: 57%). Hyperpolarised gas MRI-guided BT reduced the number of radiofrequency activations, and resulted in asthma quality of life and control improvements at 12 months that were non-inferior to standard BT.

Long-term modulation of airway remodeling in severe asthma following bronchial thermoplasty

RATIONALE

Bronchial thermoplasty is a mechanical therapeutic intervention that has been advocated as an effective treatment option for severe asthma. The mechanism is promoted as being related to the attenuation of airway smooth muscle which has been shown to occur in the short-term. However, long-term studies of the effects of bronchial thermoplasty on airway remodeling are few with only limited assessment of airway remodeling indices.

OBJECTIVES

To evaluate the effect of bronchial thermoplasty on (a) airway epithelial and smooth muscle cells in culture, and (b), airway remodeling in patients with severe asthma who have been prescribed bronchial thermoplasty up to 12-months post-treatment.

METHODS

The distribution of heat within the airway by bronchial thermoplasty was assessed in a porcine model. Culture of human airway smooth muscle cells and bronchial epithelial cells evaluated the impact of thermal injury. Histological evaluation and morphometric assessment were performed on bronchial biopsies obtained from severe asthma patients at baseline, 6-weeks, and 12-months following bronchial thermoplasty.

RESULTS

Bronchial thermoplasty resulted in heterogenous heating of the airway wall. Airway smooth muscle cell cultures sustained thermal injury, whilst bronchial epithelial cells were relatively resistant to heat. Airway smooth muscle and neural bundles were significantly reduced at 6-weeks and 12-months post-treatment. At 6-weeks post treatment, submucosal collagen was reduced, and vessel density increased, with both indices returning to baseline at 12-months. Goblet cell numbers, submucosal gland area and subbasement membrane thickness, were not significantly altered at any timepoint examined.

CONCLUSIONS

Bronchial thermoplasty primarily affects airway smooth muscle and nerves with the effects still present at 12-months post-treatment.

Bronchoscopic management of asthma, COPD and emphysema

In recent years, many bronchoscopic techniques have been developed in chronic obstructive airway inflammatory diseases, including asthma, COPD and emphysema. The main techniques with available data from randomised controlled trials are: 1) bronchial thermoplasty in asthma; 2) valves, coils and thermal vapor ablation in emphysema; and 3) targeted lung denervation in COPD. The objectives of this article are to describe the levels of evidence for efficacy and safety, long-term follow-up results beyond 1 year, and current recommendations for clinical practice from international guidelines for each technique.

Bronchial thermoplasty: Redefining its role

In this review, we trace (i) the origins of bronchial thermoplasty, (ii) the development of a solid evidence base for efficacy and safety, (iii) the emerging understanding of the pathophysiological mechanisms of action and (iv) the place in therapy today. Future challenges are then discussed.

Asthma: A Loss of Post-natal Homeostatic Control of Airways Smooth Muscle With Regression Toward a Pre-natal State

The defining feature of asthma is loss of normal post-natal homeostatic control of airways smooth muscle (ASM). This is the key feature that distinguishes asthma from all other forms of respiratory disease. Failure to focus on impaired ASM homeostasis largely explains our failure to find a cure and contributes to the widespread excessive morbidity associated with the condition despite the presence of effective therapies. The mechanisms responsible for destabilizing the normal tight control of ASM and hence airways caliber in post-natal life are unknown but it is clear that atopic inflammation is neither necessary nor sufficient. Loss of homeostasis results in excessive ASM contraction which, in those with poor control, is manifest by variations in airflow resistance over short periods of time. During viral exacerbations, the ability to respond to bronchodilators is partially or almost completely lost, resulting in ASM being "locked down" in a contracted state. Corticosteroids appear to restore normal or near normal homeostasis in those with poor control and restore bronchodilator responsiveness during exacerbations. The mechanism of action of corticosteroids is unknown and the assumption that their action is solely due to "anti-inflammatory" effects needs to be challenged. ASM, in evolutionary terms, dates to the earliest land dwelling creatures that required muscle to empty primitive lungs. ASM appears very early in embryonic development and active peristalsis is essential for the formation of the lungs. However, in post-natal life its only role appears to be to maintain airways in a configuration that minimizes resistance to airflow and dead space. In health, significant constriction is actively prevented, presumably through classic negative feedback loops. Disruption of this robust homeostatic control can develop at any age and results in asthma. In order to develop a cure, we need to move from our current focus on immunology and inflammatory pathways to work that will lead to an understanding of the mechanisms that contribute to ASM stability in health and how this is disrupted to cause asthma. This requires a radical change in the focus of most of "asthma research."

Effectiveness of mepolizumab for eosinophilic pneumonia following bronchial thermoplasty

A 57-year-old woman with poorly controlled diabetes was admitted to our hospital for additional treatment of severe asthma. Although bronchial thermoplasty was performed in the both upper lobes, cough and dyspnoea gradually appeared 2 weeks later. High-resolution computed tomography revealed thickness of intralobular septa and a diffuse ground-glass attenuation in the lung fields. Laboratory examination revealed elevated levels of serum eosinophils and total immunoglobulin E. Bronchoalveolar lavage fluid showed a remarkable increase of eosinophils as high as 48.5%, then eosinophilic pneumonia was diagnosed. Although treatment with steroids resulted in an improvement of eosinophilic pneumonia, the treatment was discontinued after 4 days because it worsened her diabetic condition. Since eosinophilic pneumonia recurred after discontinuing steroid, mepolizumab was administered, which subsequently improved her disease condition. Clinicians should be aware that bronchial thermoplasty can lead to eosinophilic pneumonia and mepolizumab might be an effective treatment in this setting.

Bronchial Thermoplasty

Bronchial thermoplasty is an advanced therapy for severe asthma. It is a bronchoscopic procedure in which radiofrequency energy is applied to the airway wall, resulting in decreased airway smooth muscle burden. Human trials have shown that bronchial thermoplasty may reduce asthma exacerbations and improve quality of life in patients with severe uncontrolled asthma. It has been demonstrated to be a safe procedure, with most adverse events being early and mild. More studies are required to understand the precise effects of bronchial thermoplasty on the asthmatic airway and optimal parameters to appropriately select patients for this novel procedure.

Bronchial thermoplasty for severe asthma: A position statement of the Indian chest society

Bronchial thermoplasty (BT) is an interventional bronchoscopic treatment for severe asthma. There is a need to define patient selection criteria to guide clinicians in offering the appropriate treatment options to patients with severe asthma.

METHODOLOGY

An expert group formed this statement under the aegis of the Indian Chest Society. We performed a systematic search of the MEDLINE and EMBASE databases to extract evidence on patient selection and the technical performance of BT.

RESULTS

The experts agreed that the appropriate selection of patients is crucial and proposed identification of the asthma phenotype, a screening algorithm, and inclusion/exclusion criteria for BT. In the presence of atypical clinical or chest radiograph features, there should be a low threshold for obtaining a thoracic computed tomography scan before BT. The patient should not have had an asthma exacerbation in the preceding two weeks from the day of the procedure. A 5-day course of glucocorticoid should be administered, beginning three days before the procedure day, and continued until the day following the procedure. General Anesthesia (total intravenous anesthesia with a neuromuscular blocker) provides ideal conditions for performing BT. A thin bronchoscope with a 2.0 mm working channel is preferable. An attempt should be made to deliver the maximum radiofrequency activations. Middle lobe treatment is not recommended. Following the procedure, overnight observation in the hospital, and a follow-up visit, a week following each treatment session, is desirable.

CONCLUSION

This position statement provides practical guidance regarding patient selection and the technical performance of BT for severe asthma.

Recent Developments In Bronchial Thermoplasty For Severe Asthma

PURPOSE

Bronchial thermoplasty is approved in many countries worldwide as a non-pharmacological treatment for severe asthma. This review summarizes recent publications on the selection of patients with severe asthma for bronchial thermoplasty, predictors of a beneficial response and developments in the procedure and discusses specific issues about bronchial thermoplasty including effectiveness in clinical practice, mechanism of action, cost-effectiveness, and place in management.

RESULTS

Bronchial thermoplasty is a treatment option for patients with severe asthma after assessment and management of causes of difficult-to-control asthma, such as nonadherence, poor inhaler technique, comorbidities, under treatment, and other behavioral factors. Patients treated with bronchial thermoplasty in clinical practice have worse baseline characteristics and comparable clinical outcomes to clinical trial data. Bronchial thermoplasty causes a reduction in airway smooth muscle mass although it is uncertain whether this effect explains its efficacy since other mechanisms of action may be relevant, such as alterations in airway epithelial, gland, and/or nerve function; improvements in small airway function; or a placebo effect. The cost-effectiveness of bronchial thermoplasty is greater in countries where the costs of hospitalization and emergency department are high. The place of bronchial thermoplasty in the management of severe asthma is not certain, although some experts propose that bronchial thermoplasty should be considered for patients with severe asthma associated with non-type 2 inflammation or who fail to respond favorably to biologic therapies targeting type 2 inflammation.

CONCLUSION

Bronchial thermoplasty is a modestly effective treatment for severe asthma after assessment and management of causes of difficult-to-control asthma. Asthma morbidity increases during and shortly after treatment. Follow-up studies provide reassurance on the long-term safety of the procedure. Uncertainties remain about predictors of response, mechanism(s) of action, and place in management of severe asthma.

Efficacy of bronchial thermoplasty in patients with severe asthma

Objective: To investigate the efficacy and safety of bronchial thermoplasty (BT) in clinical practice in adults with severe, refractory asthma.Methods: Prospective, single-center, open, observational study comprising patients with uncontrolled asthma (asthma control questionnaire (ACQ) >1.5) and/or frequent exacerbations despite treatment with at least high dose inhaled corticosteroids plus a second controller. Efficacy outcomes was change from baseline 4, 8, 12 and 24 months in FEV₁, FVC and FEV₁/FVC ratio, asthma control questionnaire (ACQ) score and asthma quality of life score (mini-AQLQ). Results are presented as median with interquartile ranges (IQR). The following were recorded as adverse events: Un-scheduled health care contacts, rescue courses of oral corticosteroid (OCS) and/or antibiotics for exacerbation for exacerbations/respiratory tract infections (RTI).Results: Six-teen patients were enrolled (nine males, median age 50 years; 14 followed for 24 months). Compared to baseline, an improvement in FEV₁, FVC, FEV₁/FVC ratio, mini-AQLQ and ACQ was observed, i.e.FEV₁ (IQR) 1.98 L (1.65-2.45) vs. 2.45 L (2.09-2.93) (p = 0.006), FVC (IQR) 3.23 L (2.76-4.05) vs. 3.75 L (3.22-4.36) (p = 0.041), FEV₁/FVC 0.60 (IQR: 0.55-0.70) vs. 0.66 (IQR: 0.63-0.71) (p = 0.016), mini-AQLQ 4.0 (IQR: 3.2-4.9) vs. 5.6 (IQR 4.5-6.5) (p = 0.008, and ACQ 2.9 (IQR: 2.1-3.7) versus 1.5 (IQR 1.0-2.4) (p = 0.004). On the other hand, an increase was observed in unscheduled visits (p = 0.005), as well as use of OCS and antibiotics (p = 0.009 and p = 0.003, respectively).Conclusion: BT in adults with severe asthma improved ACQ, mini-AQLQ and lung function, but resulted in an increased frequency of unscheduled doctor-visits and rescue courses of OCS and antibiotics.

Regulation of Airway Smooth Muscle Contraction in Health and Disease

Airway smooth muscle (ASM) extends from the trachea throughout the bronchial tree to the terminal bronchioles. In utero, spontaneous phasic contraction of fetal ASM is critical for normal lung development by regulating intraluminal fluid movement, ASM differentiation, and release of key growth factors. In contrast, phasic contraction appears to be absent in the adult lung, and regulation of tonic contraction and airflow is under neuronal and humoral control. Accumulating evidence suggests that changes in ASM responsiveness contribute to the pathophysiology of lung diseases with lifelong health impacts.Functional assessments of fetal and adult ASM and airways have defined pharmacological responses and signaling pathways that drive airway contraction and relaxation. Studies using precision-cut lung slices, in which contraction of intrapulmonary airways and ASM calcium signaling can be assessed simultaneously in situ, have been particularly informative. These combined approaches have defined the relative importance of calcium entry into ASM and calcium release from intracellular stores as drivers of spontaneous phasic contraction in utero and excitation-contraction coupling.Increased contractility of ASM in asthma contributes to airway hyperresponsiveness. Studies using animal models and human ASM and airways have characterized inflammatory and other mechanisms underlying increased reactivity to contractile agonists and reduced bronchodilator efficacy of β₂-adrenoceptor agonists in severe diseases. Novel bronchodilators and the application of bronchial thermoplasty to ablate increased ASM within asthmatic airways have the potential to overcome limitations of current therapies. These approaches may directly limit excessive airway contraction to improve outcomes for difficult-to-control asthma and other chronic lung diseases.

In vivo multifunctional optical coherence tomography at the periphery of the lungs

Remodeling of tissue, such as airway smooth muscle (ASM) and extracellular matrix, is considered a key feature of airways disease. No clinically accepted diagnostic method is currently available to assess airway remodeling or the effect of treatment modalities such as bronchial thermoplasty in asthma, other than invasive airway biopsies. Optical coherence tomography (OCT) generates cross-sectional, near-histological images of airway segments and enables identification and quantification of airway wall layers based on light scattering properties only. In this study, we used a custom motorized OCT probe that combines standard and polarization sensitive OCT (PS-OCT) to visualize birefringent tissue in vivo in the airway wall of a patient with severe asthma in a minimally invasive manner. We used optic axis uniformity (OAxU) to highlight the presence of uniformly arranged fiber-like tissue, helping visualizing the abundance of ASM and connective tissue structures. Attenuation coefficient images of the airways are presented for the first time, showing superior architectural contrast compared to standard OCT images. A novel segmentation algorithm was developed to detect the surface of the endoscope sheath and the surface of the tissue. PS-OCT is an innovative imaging technique that holds promise to assess airway remodeling including ASM and connective tissue in a minimally invasive, real-time manner.

Bronchial Thermoplasty Including the Middle Lobe Bronchus Significantly Improves Lung Function and Quality of Life in Patients Suffering from Severe Asthma

PURPOSE

Bronchial Thermoplasty (BT) is indicated in patients suffering from severe and symptomatic bronchial asthma despite maximal medical therapy. However, treatment of the right middle lobe (RML) bronchus is currently not recommended. The aim of this study was to investigate the safety and efficacy of BT if the RML bronchus is included.

METHODS

BT was performed in 17 consecutive patients, quality of life and pulmonary function were characterized before and 90 days after BT completion. Furthermore, we performed a clean-up bronchoscopy following every BT. This study was approved by the IRB of the University of Essen (No. 17-7356 BO) and registered as a retrospective observational study at the German Clinical Trials Registry (No. DRKS 00011550).

RESULTS

The median baseline values of FEV1 and Asthma Questionnaire of Life Quality (AQLQ) were 1.33 l (0.91; 1.73) and 3.01 (2.76; 3.61), respectively, and significantly improved 90 days after treatment with FEV 1 at 1.75 l (p-value 0.002) and AQLQ 3.8 (p-value < 0.05). Also the amount of oral corticosteroid necessity decreased significantly. No severe adverse events occurred due to the procedure. Clean-up bronchoscopies-when performed-revealed significant fibrinous exudation after every BT procedure.

CONCLUSION

BT including the RML bronchus is feasible. Functionally limited patients with severe asthma could potentially profit. Due to the relevant fibrinous exudation, BT should be followed by clean-up bronchoscopy, not only after RML treatment.

Interventional Pulmonology: A Focused Review for Primary Care Physicians

Interventional pulmonology (IP) has evolved in recent decades, and recent advances have greatly expanded the services offered by IP physicians. IP is best defined as the use of advanced techniques for the evaluation and treatment of benign and malignant pulmonary disorders. The field has further advanced with the recent establishment of a board certification via the American Association of Bronchology and Interventional Pulmonology and the release in 2017 of accreditation standards for specialized fellowship training. This article provides a broad overview of the field to serve as a resource for primary care physicians.

Bronchial Thermoplasty: A Decade of Experience: State of the Art

Bronchial thermoplasty (BT) delivers targeted radiofrequency energy to bronchial airway walls and results in the partial ablation of the airway smooth muscle that is responsible for bronchoconstriction. It is approved for the treatment of severe persistent asthma. Multiple, large clinical trials including a recent "real-world" study demonstrate significant improvements in asthma-related quality of life, reduction in asthma exacerbations, emergency department visits, and hospitalizations after BT that is sustained out to 5 years. In this article, we review the state of the art of BT treatment in severe persistent asthma and share a decade of BT research and clinical experience. We share our personal experience and introduce the three "I"s (identification, implementation, and intense follow-up) that we believe promote successful patient outcomes and help build a successful BT program.

Bronchial thermoplasty as a treatment for severe asthma: controversies, progress and uncertainties

INTRODUCTION

Bronchial thermoplasty is a licensed non-pharmacological treatment for severe asthma. Area covered: This article considers evidence for the efficacy and safety of bronchial thermoplasty from clinical trials and observational studies in clinical practice. Its place in the management of severe asthma, predictors of response and mechanisms of action are reviewed. Expert commentary: Bronchial thermoplasty improves quality of life and reduces exacerbations in moderate to severe asthma. Morbidity from asthma is increased during treatment. Overall, patients treated in clinical practice have worse baseline characteristics and comparable clinical outcomes to trial data. Follow-up studies provide reassurance on long-term safety. Despite some progress, future research needs to investigate uncertainties about predictors of response, mechanism of action and place in management of asthma.

Nonpharmacologic Therapy for Severe Persistent Asthma

The treatment of asthma largely depends on guideline-based pharmacologic therapies. However, nonpharmacologic therapies for asthma such as pulmonary rehabilitation, focused breathing techniques, and bronchial thermoplasty have an important, yet underappreciated, role. Structured pulmonary rehabilitation programs can reduce dyspnea and increase cardiopulmonary fitness. The educational component of these programs can ensure that therapies are being used appropriately, increase compliance, and decrease health care utilization. Studies have demonstrated a reduction in inflammatory mediators in patients with asthma who are engaged in an exercise program. Focused breathing techniques are commonly used by patients with asthma, yet benefit has not been clearly shown in randomized controlled trials. For the patients with severe asthma who are unresponsive to maximum medical therapy and have evidence of airway remodeling, bronchial thermoplasty has demonstrated long-term improvement in quality of life and reduction in severe exacerbations and health care utilization. Recent airway biopsy studies have demonstrated bronchial thermoplasty's disease-modifying effect on smooth muscle, inflammatory mediators, and bronchial nerve endings. These nonpharmacologic therapies are complementary to current guideline-based treatment, including the use of biologic modifiers, for severe asthma.

Bronchial Thermoplasty: A Nonpharmacologic Therapy for Severe Asthma

Bronchial thermoplasty is an innovative treatment for patients with severe asthma and chronic airflow obstruction with an established long-term efficacy and safety profile. This review focuses on the role of bronchial thermoplasty in severe asthma, its mechanism of action, appropriate patient selection, current evidence, and recent developments of this therapy.

Long-term outcomes of bronchial thermoplasty in subjects with severe asthma: a comparison of 3-year follow-up results from two prospective multicentre studies

Bronchial thermoplasty is an endoscopic therapy for severe asthma. The previously reported, randomised sham-controlled AIR2 (Asthma Intervention Research 2) trial showed a significant reduction in severe asthma exacerbations, emergency department visits and hospitalisations after bronchial thermoplasty. More “real-world” clinical outcome data is needed.

This article compares outcomes in bronchial thermoplasty subjects with 3 years of follow-up from the ongoing, post-market PAS2 (Post-FDA Approval Clinical Trial Evaluating Bronchial Thermoplasty in Severe Persistent Asthma) study with those from the AIR2 trial.

279 subjects were treated with bronchial thermoplasty in the PAS2 study. We compared the first 190 PAS2 subjects with the 190 bronchial thermoplasty-treated subjects in the AIR2 trial at 3 years of follow-up. The PAS2 subjects were older (mean age 45.9 versus 40.7 years) and more obese (mean body mass index 32.5 versus 29.3 kg·m⁻²) and took higher doses of inhaled corticosteroids (mean dose 2301 versus 1961 μg·day⁻¹). More PAS2 subjects had experienced severe exacerbations (74% versus 52%) and hospitalisations (15.3% versus 4.2%) in the 12 months prior to bronchial thermoplasty. At year 3 after bronchial thermoplasty, the percentage of PAS2 subjects with severe exacerbations, emergency department visits and hospitalisations significantly decreased by 45%, 55% and 40%, respectively, echoing the AIR2 results.

The PAS2 study demonstrates similar improvements in asthma control after bronchial thermoplasty compared with the AIR2 trial despite enrolling subjects who may have had poorer asthma control.

A comparison of the results obtained thus far in PAS2 with AIR2 evaluating bronchial thermoplasty in severe asthmahttp://ow.ly/sB0X30csDuE

Use of MDCT to Assess the Results of Bronchial Thermoplasty

OBJECTIVE

The purpose of this study was to evaluate the use of MDCT to assess response to bronchial thermoplasty treatment for severe persistent asthma.

MATERIALS AND METHODS

MDCT data from 26 patients with severe persistent asthma who underwent imaging before and after bronchial thermoplasty were analyzed retrospectively. Changes in the following parameters were assessed: total lung volume, mean lung density, airway wall thickness, CT air trapping index (attenuation < -856 HU), and expiratory-inspiratory ratio of mean lung density (E/I index). Asthma Quality of Life Questionnaire score changes were also assessed.

RESULTS

Median total lung volumes before and after bronchial thermoplasty were 2668 mL (range, 2226-3096 mL) and 2399 mL (range, 1964-2802 mL; p = 0.08), respectively. Patients also showed a pattern of obstruction improvement in air trapping values (median before thermoplasty, 14.25%; median after thermoplasty, 3.65%; p < 0.001] and in mean lung density values ± SD (before thermoplasty, -702 ± 72 HU; after thermoplasty, -655 ± 66 HU; p < 0.01). Median airway wall thickness also decreased after bronchial thermoplasty (before thermoplasty, 1.5 mm; after thermoplasty, 1.1 mm; p < 0.05). There was a mean Asthma Quality of Life Questionnaire overall score change of 1.00 ± 1.35 (p < 0.001), indicating asthma clinical improvement.

CONCLUSION

Our study showed improvement in CT measurements after bronchial thermoplasty, along with Asthma Quality of Life Questionnaire score changes. Thus, MDCT could be useful for imaging evaluation of patients undergoing this treatment.

Emerging understanding of the mechanism of action of Bronchial Thermoplasty in asthma

Bronchial Thermoplasty (BT) is an endoscopic treatment for moderate-to-severe asthma patients who are uncontrolled despite optimal medical therapy. Effectiveness of BT has been demonstrated in several randomized clinical trials. However, the asthma phenotype that benefits most of this treatment is unclear, partly because the mechanism of action is incompletely understood. BT was designed to reduce the amount of airway smooth muscle (ASM), but additional direct and indirect effects on airway pathophysiology are expected. This review will provide an overview of the different components of airway pathophysiology including remodeling, with the ASM as the key player. Current concepts in the understanding of BT clinical effectiveness with a focus on its impact on airway remodeling will be reviewed.

Personalised medicine in asthma: from curative to preventive medicine

The concept of asthma has changed substantially in recent years. Asthma is now recognised as a heterogeneous entity that is complex to treat. The subdivision of asthma, provided by "cluster" analyses, has revealed various groups of asthma patients who share phenotypic features. These phenotypes underlie the need for personalised asthma therapy because, in contrast to the previous approach, treatment must be tailored to the individual patient. Determination of the patient's asthma phenotype is therefore essential but sometimes challenging, particularly in elderly patients with a multitude of comorbidities and a complex exposure history. This review first describes the various asthma phenotypes, some of which were defined empirically and others through cluster analysis, and then discusses personalisation of the patient's diagnosis and therapy, addressing in particular biological therapies and patient education. This personalised approach to curative medicine should make way in the coming years for personalised preventive and predictive medicine, focused on subjects at risk who are not yet ill, with the aim of preventing asthma before it occurs. The concept of personalised preventive medicine may seem a long way off, but is it really?

Propofol and Remifentanil Sedation for Bronchial Thermoplasty: A Prospective Cohort Trial

BACKGROUND

Bronchial thermoplasty (BT) is a rapidly emerging bronchoscopic treatment for patients with moderate-to-severe asthma. Different sedation strategies are currently used, ranging from mild midazolam sedation to general anesthesia requiring tracheal intubation.

OBJECTIVES

The aim of this study was to assess the feasibility, safety, and both patients' and bronchoscopists' satisfaction with propofol and remifentanil sedation administered by specialized sedation anesthesiology nurses during BT in severe asthma patients.

METHODS

A prospective observational cohort study in BT-treated severe asthma patients of the TASMA trial was designed. Patients were asked to rate their overall BT procedure satisfaction and tolerance with propofol/remifentanil sedation using a visual analogue scale (VAS) ranging from 0 to 10. Similarly, bronchoscopists were asked to rate patient cooperation and tolerance. Sedation-associated adverse events and the number of BT activations were recorded.

RESULTS

Thirty-two BT procedures in 13 severe asthma patients were performed under moderate target-controlled infusion (TCI) propofol/remifentanil sedation. Patients' median VAS scores were as follows: overall satisfaction 9.6 (interquartile range [IQR] 8.5-10.0), dyspnea 0.0 (IQR 0.0-0.6), pain 0.1 (IQR 0.0-1.0), cough 0.5 (IQR 0.0-2.1), and anxiety 0.1 (IQR 0.0-0.7). Bronchoscopists' median VAS scores were as follows: overall patient cooperation 9.1 (IQR 8.5-9.6), dyspnea 0.3 (IQR 0.0-0.9), pain 0.2 (IQR 0.0-1.3), cough 1.2 (IQR 0.7-2.0), and discomfort 0.6 (IQR 0.3-1.5). All patients were willing to undergo the procedure again and would recommend this form of sedation to their best friend. One case of conversion to general anesthesia occurred and no serious adverse events were reported.

CONCLUSIONS

Moderate sedation with propofol and remifentanil TCI provided by specialized sedation anesthesiology nurses is feasible and safe and results in high satisfaction rates of both patients and bronchoscopists.

Advances in Bronchial Thermoplasty

Bronchial thermoplasty (BT) is a therapeutic intervention that delivers targeted thermal energy to the airway walls with the goal of ablating the smooth muscle in patients with severe persistent asthma. Since the publication of the original preclinical studies, three large randomized clinical trials evaluating its impact on asthma control have been performed. These trials have shown improvements in asthma-related quality of life and a reduction in asthma exacerbations following treatment with BT. However, there remains significant controversy regarding the true efficacy of BT and the interpretation of these studies, particularly the Asthma Intervention Research 2 trial. In this article, we will discuss these controversies and present the latest evidence on the use of BT in asthma, specifically the 5-year longitudinal evaluation of patients. In addition, we will discuss new insights into the histopathologic changes that occur in the airways following BT, as well as the feasibility of performing the procedure in patients with very severe asthma. We also will discuss the ongoing translational and clinical investigations regarding the underlying mechanism of action and methods to improve patient selection for this procedure.

Historical perspectives of bronchoscopy. Connecting the dots

The era of bronchoscopy began with Gustav Killian in 1876 when he removed a pork bone from a farmer's airway, using an esophagoscope. Prompted by this accomplishment, Chevalier Jackson, an American otolaryngologist, laid the platform for the modern-day rigid bronchoscope in the early twentieth century. In 1967 Shigeto Ikeda revolutionized the field of bronchoscopy by his innovation of the fiberoptic bronchoscope. Today, bronchoscopy and interventional pulmonology have become an integral part of pulmonary medicine and an established subspecialty. Numerous innovators have furthered the horizons of this technology. In the early 1980s Ko-Pen Wang introduced transbronchial needle aspiration to sample mediastinal lesions while Jean-François Dumon developed methods for laser photoresection and for placing stents thorough the bronchoscope. More recently, application of endobronchial ultrasound and electromagnetic navigation tools has further galvanized the role of bronchoscopy. The success of lung transplantation also belongs in part to flexible bronchoscopy. Today, researchers are looking into treating emphysema as well as asthma, using bronchoscopic techniques. We believe 2015 is a good time to look back on the history of bronchoscopy and to recognize its major milestones. This article attempts to connect the historical dots in this field of research, with the hope that our effort helps future generations improve the welfare of patients with lung ailments.

Current and emerging treatments for severe asthma

Severe asthma, which is poorly controlled despite the elimination of modifiable factors and the correct use of standard therapy, accounts only for 5% of people with asthma but it contributes to approximately 50% of the economic costs of asthma. Because of this unmet need, novel therapies have been developed for optimal treatment of these patients. The use of tiotropium, omalizumab, mepolizumab and thermoplasty in well-selected patients provides better control and most importantly a reduction in asthma exacerbations.

Long-term efficacy and safety of bronchial thermoplasty in patients with moderate-to-severe persistent asthma: a systemic review and meta-analysis

OBJECTIVE

To evaluate the long-term efficacy and safety of bronchial thermoplasty (BT) in the treatment of patients with moderate-to-severe persistent asthma.

METHODS

We therefore performed a systematic literature review of peer-reviewed studies focusing on BT intervention in asthma control published between January 2000 and June 2014. Three randomized controlled studies and extension studies met the inclusion criteria (n = 6). Outcomes assessed after BT included spirometric data, adverse respiratory events, emergency room (ER) visits and hospitalization for respiratory illness. One-year and 5-year follow-up data were defined as V1 and V5, respectively.

RESULTS

There were 249 BT-treated subjects in total who had a 1-year follow-up (V1), whereas 216 of them finished a 5-year follow-up (V5). No evidence of significant decline was found in pre-bronchodilator FEV1 (% predicted) (WMD = 0.75; 95% CI: 3.36 to 1.85; p = 0.57), or in post-bronchodilator FEV1 (% predicted) (WMD = 0.62; 95% CI: 3.32 to 2.08; p = 0.65) between V1 and V5. In addition, the frequency of respiratory adverse events was reduced significantly during the follow-up (RR = 3.41, 95% CI: 2.96-3.93, p < 0.00001). The number of ER visits for adverse respiratory events remained unchanged (RR = 1.06, 95% CI: 0.77-1.46, p = 0.71) after BT treatment. There was no statistically significant increase in the incidence of hospitalization for respiratory adverse events (V5 vs. V1, RR = 1.47, 95% CI: 0.69-3.12, p = 0.32).

CONCLUSIONS

These data demonstrate long-term benefits of BT with regard to both asthma control and safety for moderate-to-severe asthmatic patients.

Cost effectiveness of bronchial thermoplasty in patients with severe uncontrolled asthma

RATIONALE

Based on its clinical effectiveness, bronchial thermoplasty (BT) was approved by the Food and Drug Administration in 2010 for the treatment of severe persistent asthma in patients 18 years and older whose asthma is not well-controlled with inhaled corticosteroids and long-acting beta-agonist medicines.

OBJECTIVE

Assess the 10 year cost-effectiveness of BT for individuals with severe uncontrolled asthma.

METHODS

Using a Markov decision analytic model, the cost-effectiveness of BT was estimated. The patient population involved a hypothetical cohort of 41-year-old patients comparing BT to usual care over a 10-year time frame. The main outcome measure was cost in 2013 dollars per additional quality adjusted life year (QALY).

RESULTS

Treatment with BT resulted in 6.40 QALYs and $7512 in cost compared to 6.21 QALYs and $2054 for usual care. The incremental cost-effectiveness ratio for BT at 10 years was $29,821/QALY. At a willingness to pay per QALY of $50,000, BT continues to be cost effective unless the probability of severe asthma exacerbation drops below 0.63 exacerbation per year or the cost of BT rises above $10,384 total for all three bronchoscopic procedures needed to perform thermoplasty and to cover the entire bronchial tree (baseline = $6690).

CONCLUSIONS

BT is a cost-effective treatment for asthmatics at high risk of exacerbations. Continuing to follow asthmatics treated with BT beyond 5 years will help inform longer efficacy and support its cost-effectiveness.

Bronchial thermoplasty: a new therapeutic option for the treatment of severe, uncontrolled asthma in adults

Bronchial thermoplasty is a young yet promising treatment for severe asthma whose benefit for long-term asthma control outweighs the short-term risk of deterioration and hospitalisation in the days following the treatment. It is an innovative treatment whose clinical efficacy and safety are beginning to be better understood. Since this is a device-based therapy, the overall evaluation of risk-benefit is unlike that of pharmaceutical products; safety aspects, regulatory requirements, study design and effect size assessment may be unfamiliar. The mechanisms of action and optimal patient selection need to be addressed in further rigorous clinical and scientific studies. Bronchial thermoplasty fits in perfectly with the movement to expand personalised medicine in the field of chronic airway disorders. This is a device-based complimentary asthma treatment that must be supported and developed in order to meet the unmet needs of modern severe asthma management. The mechanisms of action and the type of patients that benefit from bronchial thermoplasty are the most important challenges for bronchial thermoplasty in the future.

The Three A's in Asthma - Airway Smooth Muscle, Airway Remodeling & Angiogenesis

Asthma affects more than 300 million people worldwide and its prevalence is still rising. Acute asthma attacks are characterized by severe symptoms such as breathlessness, wheezing, tightness of the chest, and coughing, which may lead to hospitalization or death. Besides the acute symptoms, asthma is characterized by persistent airway inflammation and airway wall remodeling. The term airway wall remodeling summarizes the structural changes in the airway wall: epithelial cell shedding, goblet cell hyperplasia, hyperplasia and hypertrophy of the airway smooth muscle (ASM) bundles, basement membrane thickening and increased vascular density. Airway wall remodeling starts early in the pathogenesis of asthma and today it is suggested that remodeling is a prerequisite for other asthma pathologies. The beneficial effect of bronchial thermoplasty in reducing asthma symptoms, together with the increased potential of ASM cells of asthmatics to produce inflammatory and angiogenic factors, indicate that the ASM cell is a major effector cell in the pathology of asthma. In the present review we discuss the ASM cell and its role in airway wall remodeling and angiogenesis.

Bronchial thermoplasty in asthma: current perspectives

Bronchial thermoplasty (BT) is a novel therapy for patients with severe asthma. Using radio frequency thermal energy, it aims to reduce the airway smooth muscle mass. Several clinical trials have demonstrated improvements in asthma-related quality of life and a reduction in the number of exacerbations following treatment with BT. In addition, recent data has demonstrated the long-term safety of the procedure as well as sustained improvements in rates of asthma exacerbations, reduction in health care utilization, and improved quality of life. Further study is needed to elucidate the underlying mechanisms that result in these improvements. In addition, improved characterization of the asthma subphenotypes likely to exhibit the largest clinical benefit is a critical step in determining the precise role of BT in the management of severe asthma.

Lung abscess as a complication of bronchial thermoplasty

BACKGROUND

Bronchial thermoplasty (BT) is an emerging treatment modality for patients with difficult to treat asthma. It has been shown to be beneficial for symptom control and improves quality of life and reduces frequency of hospitalization. Safety data from the two major trials of BT indicate that patients who undergo these procedures are most likely to experience adverse respiratory events in the first six weeks post treatment. Lung abscess has never been reported as a direct complication of BT. In this case; we report a lung abscess as an immediate complication of BT, which we believe may be the first case.

CASE PRESENTATION

We describe a forty three year old Caucasian female presented three days post-bronchial thermoplasty with left sided chest pain radiating to the back associated with shortness of breath, wheeze and dry cough. She had also started to feel hot and cold and generally unwell.

CONCLUSION

It remains unclear why this patient developed a lung abscess so acutely post BT treatment. It is important that safety data continues to be collated and published as the procedure becomes more widely available with further long term follow-up in particular.

Critical review of bronchial thermoplasty: where should it fit into asthma therapy?

Bronchial thermoplasty is a device-based therapy for treatment of severe refractory asthma that uses radiofrequency energy to reduce airway smooth muscle and decrease bronchoconstriction. BT improves quality of life and decreases the rate of severe exacerbations with no known major long-term complications. The effectiveness of bronchial thermoplasty persists at least 5 years after the treatment is completed. Further investigation is needed to better define the specific subpopulation of patients with severe asthma who would best benefit from this treatment.

'SIMPLES': a structured primary care approach to adults with difficult asthma

The substantial majority of patients with asthma can expect minimal breakthrough symptoms on standard doses of inhaled corticosteroids with or without additional add-on therapies. SIMPLES is a structured primary care approach to the review of a person with uncontrolled asthma which encompasses patient education monitoring, lifestyle and pharmacological management and addressing support needs which will achieve control in most patients. The small group of patients presenting with persistent asthma symptoms despite being prescribed high levels of treatment are often referred to as having 'difficult asthma'. Some will have difficult, 'therapy resistant' asthma, some will have psychosocial problems which make it difficult for them to achieve asthma control and some may prove to have an alternative diagnosis driving their symptoms. A few patients will benefit from referral to a 'difficult asthma' clinic. The SIMPLES approach, aligned with close co-operation between primary and specialist care, can identify this patient group, avoid inappropriate escalation of treatment, and streamline clinical assessment and management.

Payer coverage for bronchial thermoplasty: shifting the traditional paradigm for refractory asthma therapy

The advent of bronchial thermoplasty (BT) provides a novel therapeutic option for asthma refractory to traditional medical therapy. Insurance coverage poses significant frustration for centers performing BT. Although clinical research has provided evidence of the usefulness and long-term safety of BT, establishing "reasonability and necessity" remains a daunting challenge in securing private and governmental insurance coverage. As a result, obtaining coverage poses significant frustration for centers capable of performing BT for patients suffering from severe asthma. Until recently, BT had been categorized by a temporary set of Current Procedural Terminology (CPT) codes as an emerging technology, service, or procedure (category 3). Based on increasing implementation of BT nationwide, the American Medical Association CPT Editorial Panel has assigned category 1 CPT codes for BT in their published 2013 professional edition. It is hoped that such a recommendation will reinforce the medical community's belief in the usefulness of BT and help facilitate decisions on insurance coverage. The ability to secure coverage for BT through physician advocacy and Centers for Medicare and Medicaid Services support will help move the treatment of refractory asthma forward.

Bronchial smooth muscle cells of asthmatics promote angiogenesis through elevated secretion of CXC-chemokines (ENA-78, GRO-α, and IL-8)

Background

Airway wall remodelling is a key pathology of asthma. It includes thickening of the airway wall, hypertrophy and hyperplasia of bronchial smooth muscle cells (BSMC), as well as an increased vascularity of the sub-epithelial cell layer. BSMC are known to be the effector cells of bronchoconstriction, but they are increasingly recognized as an important source of inflammatory mediators and angiogenic factors.

Objective

To compare the angiogenic potential of BSMC of asthmatic and non-asthmatic patients and to identify asthma-specific angiogenic factors.

Methods

Primary BSMC were isolated from human airway tissue of asthmatic and non-asthmatic patients. Conditioned medium (CM) collected from BSMC isolates was tested for angiogenic capacity using the endothelial cell (EC)-spheroid invitro angiogenesis assay. Angiogenic factors in CM were quantified using a human angiogenesis antibody array and enzyme linked immunosorbent assay.

Results

Induction of sprout outgrowth from EC-spheroids by CM of BSMC obtained from asthma patients was increased compared with CM of control BSMC (twofold, p < 0.001). Levels of ENA-78, GRO-α and IL-8 were significantly elevated in CM of BSMC from asthma patients (p < 0.05 vs. non-asthmatic patients). SB 265610, a competitive antagonist of chemokine (CXC-motif) receptor 2 (CXCR2), attenuated the increased sprout outgrowth induced by CM of asthma patient-derived BSMC.

Conclusions

BSMC isolated from asthma patients exhibit increased angiogenic potential. This effect is mediated through the CXCR2 ligands (ENA78, GRO-α and IL-8) produced by BSMC.

Implications

CXCR2 ligands may play a decisive role in directing the neovascularization in the sub-epithelial cell layers of the lungs of asthma patients. Counteracting the CXCR2-mediated neovascularization by pharmaceutical compounds may represent a novel strategy to reduce airway remodelling in asthma.

Bronchial thermoplasty

Bronchial thermoplasty is a relatively new therapy for the management of severe asthma. It involves the direct bronchoscopic application of thermal energy to airways by a catheter-directed expandable basket. The airways of the lower and upper lobes are treated in 3 separate sessions spaced 3 weeks apart. The therapy targets airway smooth muscle, with studies showing a decrease in airway smooth muscle after bronchial thermoplasty therapy. After therapy, an improvement in quality of life and decrease in asthma exacerbations can be expected. Adverse events can occur with bronchial thermoplasty and careful patient selection is critical to ensure benefits outweigh the potential risks.

Novel therapies in asthma: leukotriene antagonists, biologic agents, and beyond

Asthma is one of the most common conditions seen in clinical practice and carries both a significant disease burden in terms of patient morbidity and a high economic burden in both direct and indirect costs. Despite this, it remains a comparatively poorly understood disease, with only modest advances in treatment over the past decade. Corticosteroids remain the cornerstone of therapy. Both patient compliance with medications and physician adherence to evidence-based guidelines are often poor, and a high percentage of patients continue to have inadequately controlled disease even with optimal therapy. Following a contextual overview of the current treatment guidelines, this review focuses on novel asthma therapies, beginning with the introduction of the leukotriene receptor antagonist zafirlukast in the 1990s, continuing through advanced endoscopic therapy and into cytokine-directed biologic agents currently in development. Along with clinically relevant biochemistry and pharmacology, the evidence supporting the place of these therapies in current guidelines will be highlighted along with data comparing these agents with more conventional treatment. A brief discussion of other drugs, such as those developed for unrelated conditions and subsequently examined as potential asthma therapies, is included.

Bronchial thermoplasty failure in severe persistent asthma: a case report

INTRODUCTION

Bronchial thermoplasty (BT) is an emerging therapy for patients with severe persistent asthma who remain poorly controlled despite standard maximal medical therapy. Thermoplasty elicits asthma control over time by applying thermal radiofrequency energy to airways to ablate underlying smooth muscle. While this therapy is suggested to eliminate such smooth muscle permanently, no human studies have examined the possibility of treatment failure.

CASE REPORT

We present a 62-year-old female with severe, refractory asthma symptoms who underwent BT without apparent complications. However, severe symptoms including multiple clinical exacerbations persisted despite BT treatment. Repeat endobronchial biopsy done six months after BT treatment demonstrated persistent smooth muscle hyperplasia in multiple airways that previously had been treated. The patient continued to have uncontrolled, refractory asthma despite multiple therapies.

CONCLUSION

This case is the first to describe a failure of BT to reduce or eliminate airway smooth muscle in a patient with severe persistent asthma. It suggests the potential for treatment failure in the management of these patients after BT and highlights the need for further study of potential BT-refractory patients.

Origins of increased airway smooth muscle mass in asthma

Asthma is characterized by both chronic inflammation and airway remodeling. Remodeling--the structural changes seen in asthmatic airways--is pivotal in the pathogenesis of the disease. Although significant advances have been made recently in understanding the different aspects of airway remodeling, the exact biology governing these changes remains poorly understood. There is broad agreement that, in asthma, increased airway smooth muscle mass, in part due to smooth muscle hyperplasia, is a very significant component of airway remodeling. However, significant debate persists on the origins of these airway smooth muscle cells. In this review article we will explore the natural history of airway remodeling in asthma and we will discuss the possible contribution of progenitors, stem cells and epithelial cells in mesenchymal cell changes, namely airway smooth muscle hyperplasia seen in the asthmatic airways.

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.

Bronchial thermoplasty: a new treatment paradigm for severe persistent asthma

Patients with severe asthma represent only a minority of the total asthma population; however, they account for the majority of the mortality, morbidity, and health care-related cost of this chronic illness. Bronchial thermoplasty is a novel treatment modality that employs radiofrequency energy to alter the smooth muscles of the airways. This therapy represents a radical change in our treatment paradigm from daily repetitive dosing of medications to a truly long-term and potentially permanent attenuation of perhaps the most feared component of asthma--smooth muscle-induced bronchospasm. A large, multicentered, double-blinded, randomized controlled trial employed the unprecedented (but now industry standard for bronchoscopic studies) approach of using sham bronchoscopy as a control. It demonstrated that bronchial thermoplasty is safe, improved quality of life, and decreased frequency of severe exacerbations in the treatment group compared to the control group. Although the mechanism of action of bronchial thermoplasty is not currently completely understood, it should be considered as a valid and potentially valuable option for patients who have severe persistent asthma and who remain symptomatic despite inhaled corticosteroids and long-acting beta-2 agonists. Such patients should however be carefully evaluated at centers with expertise in managing severe asthma patients and with physicians who have experience with this promising new treatment modality.