Alveolar nitric oxide in adults with asthma: evidence of distal lung inflammation in refractory asthma

Expiratory and inspiratory resistance and reactance from respiratory oscillometry defining expiratory flow limitation in obstructive lung diseases

BACKGROUND

Expiratory flow limitation (EFL) during tidal breathing and lung hyperinflation have been identified as major decisive factors for disease status, prognosis and response to therapy in obstructive lung diseases.

AIM

To investigate the delta values between expiratory and inspiratory resistance and reactance, measured using respiratory oscillometry and its correlation with air trapping and symptoms in subjects with obstructive lung diseases.

METHODS

Four hundred and seventy-one subjects (96 with chronic obstructive pulmonary disease [COPD], 311 with asthma, 30 healthy smokers and 34 healthy subjects) were included. Spirometry, body plethysmography and respiratory oscillometry measurements were performed and the differences between the expiratory and inspiratory respiratory oscillometry values (as delta values) were calculated. Questionnaires regarding symptoms and quality of life were administered.

RESULTS

Patients with COPD and healthy smokers had an increased delta resistance at 5 Hz (R5) compared with patients with asthma (p < 0.0001 and p = 0.037, respectively) and healthy subjects (p = 0.0004 and p = 0.012, respectively). Patients with COPD also had higher values of ΔR5-R19 than healthy subjects (p = 0.0001) and patients with asthma (p < 0.0001). Delta reactance at 5 Hz (X5) was significantly more impaired in COPD patients than in asthma and healthy subjects (p < 0.0001 for all). There was a correlation between the ratio of residual volume and total lung capacity and ΔR5 (p = 0.0047; r = 0.32), ΔR5-R19 (p = 0.0002; r = 0.41) and ΔX5 (p < 0.0001; r = -0.44), for all subjects. ΔX5 correlated with symptoms in COPD, healthy smokers and patients with asthma. In addition, ΔR5 correlated with asthma symptoms.

CONCLUSION

EFL was most prominent in parameters measuring peripheral resistance and reactance and correlated with air trapping and airway symptoms.

Breath and Sputum Analyses in Asthmatic Patients: An Overview

Recent advancements in asthma management include non-invasive methodologies such as sputum analysis, exhaled breath condensate (EBC), and fractional exhaled nitric oxide (FeNO). These techniques offer a means to assess airway inflammation, a critical feature of asthma, without invasive procedures. Sputum analysis provides detailed insights into airway inflammation patterns and cellular composition, guiding personalized treatment strategies. EBC collection, reflecting bronchoalveolar lining fluid composition, provides a non-invasive window into airway physiology. FeNO emerges as a pivotal biomarker, offering insights into eosinophilic airway inflammation and aiding in asthma diagnosis, treatment monitoring, and the prediction of exacerbation risks. Despite inherent limitations, each method offers valuable tools for a more comprehensive assessment of asthma. Combining these techniques with traditional methods like spirometry may lead to more personalized treatment plans and improved patient outcomes. Future research is crucial to refine protocols, validate biomarkers, and establish comprehensive guidelines in order to enhance asthma management with tailored therapeutic strategies and improved patient outcomes.

Endotyping Chronic Respiratory Diseases: T2 Inflammation in the United Airways Model

Over the past 15 years, the paradigm of viewing the upper and lower airways as a unified system has progressively shifted the approach to chronic respiratory diseases (CRDs). As the global prevalence of CRDs continues to increase, it becomes evident that acknowledging the presence of airway pathology as an integrated entity could profoundly impact healthcare resource allocation and guide the implementation of pharmacological and rehabilitation strategies. In the era of precision medicine, endotyping has emerged as another novel approach to CRDs, whereby pathologies are categorized into distinct subtypes based on specific molecular mechanisms. This has contributed to the growing acknowledgment of a group of conditions that, in both the upper and lower airways, share a common type 2 (T2) inflammatory signature. These diverse pathologies, ranging from allergic rhinitis to severe asthma, frequently coexist and share diagnostic and prognostic biomarkers, as well as therapeutic strategies targeting common molecular pathways. Thus, T2 inflammation may serve as a unifying endotypic trait for the upper and lower airways, reinforcing the practical significance of the united airways model. This review aims to summarize the literature on the role of T2 inflammation in major CRDs, emphasizing the value of common biomarkers and integrated treatment strategies targeting shared molecular mechanisms.

Small airways disease in chronic obstructive pulmonary disease

INTRODUCTION

Small airway disease (SAD) represents a common and critical feature of Chronic Obstructive Pulmonary Disease (COPD). Introduced in the '60s, SAD has gradually gained increasing interest as assessment methodologies have improved. Chronic exposure to smoking and noxious particles or gases induces inflammation and remodeling, leading to airway obstruction and SAD, eventually resulting in complete airway loss.

AREAS COVERED

A literature search up to June 2024 was performed in PubMed to identify articles on SAD and airway diseases mainly COPD, but also to the extent that it seemed relevant in the uncontrolled/severe asthma field, where SAD is better studied. We provide clinicians and translational scientists with a comprehensive analysis of the existing literature on SAD in COPD, concentrating on the underlying pathophysiological mechanisms, diagnostic techniques, and current pharmacological approaches targeting airflow obstruction in small airways.

EXPERT OPINION

Small airways are the primary site for the onset and progression of airflow obstruction in patients with COPD, with significant clinical consequences associated with poor lung function, hyperinflation, and impaired quality of life. The early identification of individuals with subclinical SAD may allow us to prevent its further progress from airway loss and potential development of emphysema and choose the appropriate therapeutic approach.

Small airways in asthma: From inflammation and pathophysiology to treatment response

Small airways are characterized as those with an inner diameter less than 2 mm and constitute a major site of pathology and inflammation in asthma disease. It is estimated that small airways dysfunction may occur before the emergence of noticeable symptoms, spirometric abnormalities and imaging findings, thus characterizing them as "the quiet or silent zone" of the lungs. Despite their importance, measuring and quantifying small airways dysfunction presents a considerable challenge due to their inaccessibility in usual functional measurements, primarily due to their size and peripheral localization. Several pulmonary function tests have been proposed for the assessment of the small airways, including impulse oscillometry, nitrogen washout, body plethysmography, as well as imaging methods. Nevertheless, none of these methods has been established as the definitive "gold standard," thus, a combination of them should be used for an effective assessment of the small airways. Widely used asthma treatments seem to also affect several parameters of the small airways. Emerging biologic treatments show promising results in reducing small airways inflammation and remodelling, providing evidence for potential alterations in the disease's progression and outcomes. These novel therapies have implications not only in the clinical aspects of asthma but also in its inflammatory and functional aspects.

Determination of Nitric Oxide and Its Metabolites in Biological Tissues Using Ozone-Based Chemiluminescence Detection: A State-of-the-Art Review

Ozone-based chemiluminescence detection (CLD) has been widely applied for determining nitric oxide (•NO) and its derived species in many different fields, such as environmental monitoring and biomedical research. In humans and animals, CLD has been applied to determine exhaled •NO and •NO metabolites in plasma and tissues. The main advantages of CLD are high sensitivity and selectivity for quantitative analysis in a wide dynamic range. Combining CLD with analytical separation techniques like chromatography allows for the analytes to be quantified with less disturbance from matrix components or impurities. Sampling techniques like microdialysis and flow injection analysis may be coupled to CLD with the possibility of real-time monitoring of •NO. However, details and precautions in experimental practice need to be addressed and clarified to avoid wrong estimations. Therefore, using CLD as a detection tool requires a deep understanding of the sample preparation procedure and chemical reactions used for liberating •NO from its derived species. In this review, we discuss the advantages and pitfalls of CLD for determining •NO species, list the different applications and combinations with other analytical techniques, and provide general practical notes for sample preparation. These guidelines are designed to assist researchers in comprehending CLD data and in selecting the most appropriate method for measuring •NO species.

Lung Involvement in Patients with Ulcerative Colitis: Relationship between Exhaled Nitric Oxide and Lung Function

Ulcerative colitis (UC) is characterized by immune system dysregulation with frequent extraintestinal manifestations, including airway involvement. A reduction in CO diffusing capacity and functional alterations in small airways have been described. An extended analysis of fractional exhaled nitric oxide (FeNO) may distinguish the sites of production, and the presence of small airway inflammation may be a useful, non-invasive marker for patient follow-up. The aim of our study was to compare the PFTs as well as FeNO and CANO values of UC patients with different clinical disease activities and healthy subjects to reveal lung function abnormalities and the presence of subclinical airway inflammation. We enrolled 42 adult outpatients at different clinical activity stages of UC (39 ± 13 years) and a healthy control group of 41 subjects (29 ± 3 years). C-reactive protein (CRP) and FeNO values at different flows (50,100, and 200 mL/s) were collected. All patients performed pulmonary function tests (PFTs) with static volumes and diffusing capacity (DLCO). FeNO and CANO values were significantly increased in UC patients when compared with controls (p = 0.0008 and p < 0.0001, respectively) and were proportional to disease activity (FeNO class 3: 28.1 ppb vs. classes 1-2: 7.7 ppb; CANO values class 3: 8.6 ppb vs. classes 1-2: 2.7 ppb (p < 0.0001)). TLC and DLCO were significantly reduced in severe (Mayo 3) UC patients (p = 0.010 and p = 0.003, respectively). The results of this study show significant lung functional abnormalities in UC patients and suggest the presence of airway inflammation directly correlated with disease activity, suggesting the need for an integrated approach in routine assessment.

Inhaled lipid nanocarriers for pulmonary delivery of glucocorticoids: previous strategies, recent advances and key factors description

In view of the strong anti-inflammatory activity of glucocorticoids (GC) they are used in the treatment of almost all inflammatory lung diseases. In particular, inhaled GC (IGC) allow high drug concentrations to be deposited in the lung and may reduce the incidence of adverse effects associated with systemic administration. However, rapid absorption through the highly absorbent surface of the lung epithelium may limit the success of localized therapy. Therefore, inhalation of GC incorporated into nanocarriers is a possible approach to overcome this drawback. In particular, lipid nanocarriers, which showed high pulmonary biocompatibility and are well known in the pharmaceutical industry, have the best prospects for pulmonary delivery of GC by inhalation. This review provides an overview of the pre-clinical applications of inhaled GC-lipid nanocarriers based on several key factors that will determine the efficiency of local pulmonary GC delivery: 1) stability to nebulization, 2) deposition profile in the lungs, 3) mucociliary clearance, 4) selective accumulation in target cells, 5) residence time in the lung and systemic absorption and 6) biocompatibility. Finally, novel preclinical pulmonary models for inflammatory lung diseases are also discussed.

The value of concentration of alveolar nitric oxide in diagnosing small airway dysfunction in patients with stable asthma

BACKGROUND

Exhaled nitric oxide (FeNO) is a simple, noninvasive, and reproducible test, and FeNO (50 ml/s) is often used to reflect airway inflammation. The peripheral small airway/alveolar nitric oxide (NO) concentration is derived from the output of NO at multiple flow rates. Concentration of alveolar NO (CANO), which has been reported to reflect peripheral small airway inflammation, may be related to parameters that reflect abnormal small airway function.

AIM

This study aims to investigate the relationship among CANO levels, clinical features, and small airway function-related indicators in patients with stable asthma and to provide a simple method for monitoring small airway function in asthma.

DESIGN AND METHODS

We recruited 144 patients with well-controlled, stable asthma, including 69 patients with normal small airway function (normal group) and 75 patients with small airway dysfunction (abnormal group). CANO and pulmonary function were measured.

RESULTS

CANO was significantly higher in the abnormal group ([7.28 ± 3.25] ppb) than the normal group CANO ([2.87 ± 1.50] ppb). FEF25-75%pred ([55.0 ± 16.5]%), FEF50%pred ([46.4 ± 13.2]%), and FEF75%pred ([41.9 ± 13.1]%) in abnormal group were significantly lower compared with normal group ([89.9 ± 7.5]%), ([80.9 ± 6.8]%), and ([73.8 ± 5.0]%). CANO was negatively correlated and FEF25-75%pred, FEF50%pred, and FEF75%pred (r = -0.87, P < 0.001; r = -0.82, P < 0.001; r = -0.78, P < 0.001). CANO was positively correlated with age (r = 0.27, P = 0.001). The area under the ROC curve was 0.875 for CANO. The optimal cutoff point of 5.3 ppb had sensitivity and specificity values of 72% and 92% in diagnosing small airway dysfunction.

CONCLUSION

CANO has diagnostic value for small airway dysfunction, and the optimal cutoff value is 5.3 ppb. However, the diagnostic evidence is still insufficient, so it still needs further exploration for its value in detecting small airway dysfunction.

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.

Is small airway dysfunction an abnormal phenomenon for patients with normal forced expiratory volume in 1 second and the ratio of forced expiratory volume in 1 second to forced vital capacity?

BACKGROUND

The clinical significance of small airway dysfunction (SAD) determined with spirometry in patients with normal forced expiratory volume in 1 second (FEV1) and the ratio of FEV1 to forced vital capacity (FVC) is controversial.

OBJECTIVE

To determine whether SAD presents histologic abnormalities in the setting of normal computed tomography (CT) imaging and FEV1 and FEV1/FVC.

METHODS

A cross-sectional study was performed in 64 patients undergoing thoracotomy for pulmonary nodules. Thoracic high-resolution CT (HRCT), bronchodilation test, and fractional exhaled nitric oxide (FENO) and its alveolar component (nitric oxide alveolar concentration [CANO]) were obtained before surgery. Lung pathology and levels of cytokines in lung tissue were measured. The patients were divided into SAD and small airway normal function groups according to forced expiratory flow at 75% and 50% of the FVC (maximal expiratory flow [MEF] 25, MEF50) and maximum midexpiratory flow.

RESULTS

The MEF50, MEF25, and maximum midexpiratory flow were strongly negatively correlated with CANO (r, -0.42, -0.42, -0.40, respectively; P ≤ .001 for all). The MEFs were mildly negatively correlated with interleukin (IL)-6 and macrophages in lung tissue (r < -0.25, P < .001 for all). The CANO (P < .001), airspace size (mean linear intercept) (P = .02), macrophages (P = .003), IL-6 (P = .003), and IL-8 (P = .008) in lung tissue were higher in patients with SAD (n = 35) than those with small airway normal function (n = 29). A total of 8 patients (22.86%) with SAD and 2 (6.90%) without SAD had pneumatoceles (P = .10).

CONCLUSION

Patients with pulmonary nodules and SAD were more likely to have abnormal inflammation and emphysematous destruction than patients without SAD. Thus, SAD indicates histologic abnormalities in patients with normal CT imaging and FEV1 and FEV1/FVC.

The potential role of SP-D as an early biomarker of severity of asthma

Surfactant decreases the surface tension of peripheral airways and modulates the immunological responses of the lung. The alterations of surfactant due to the airway inflammation suggest a role in the pathogenesis of asthma. We aim to test the hypothesis that serum levels of SP-A (Surfactant Protein A) and SP-D (Surfactant Protein-D) are altered in patients with mild asthma compared to healthy controls and those alterations are related to functional abnormalities of peripheral airways, which are an early marker of progression of asthma. In this pilot study, we recruited 20 mild asthmatics and 10 healthy controls. We measured serum SP-A and SP-D and all subjects underwent clinical, lung functional and biological assessments. Serum SP-D was significantly higher in asthmatics compared to healthy controls (mean (SD) values: 7.9(4.65) vs 3.31(1.71) ng ml^-1,p-value: 0.008). In the asthmatic group, serum SP-D was significantly correlated to CalvNO (alveolar NO concentration) (R-squared: 0.26;p-value: 0.014). These preliminary findings suggest that serum SP-D could be used as a lung-specific biomarker of small airways damage thus predicting the progression to the most severe forms of asthma.

Small airway function in Finnish COVID-19 survivors

Follow-up studies of COVID-19 patients have found lung function impairment up to six months after initial infection, but small airway function has not previously been studied. Patients (n = 20) hospitalised for a severe SARS-CoV-2 infection underwent spirometry, impulse oscillometry, and multiple measurements of alveolar nitric oxide three to six months after acute infection. None of the patients had small airway obstruction, nor increased nitric oxide concentration in the alveolar level. None of the patients had a reduced FEV₁/FVC or significant bronchodilator responses in IOS or spirometry. In conclusion, we found no evidence of inflammation or dysfunction in the small airways.

Targeting dynamic hyperinflation in moderate-to-severe asthma: a randomised controlled trial

Background

Dynamic hyperinflation is highly prevalent in moderate-to-severe asthma, which may significantly impede activities of daily life. We hypothesised that dynamic hyperinflation in asthma is due to inflammation of large and small airways and can be reduced by systemic anti-inflammatory treatment. Therefore, we investigated the effect of systemic glucocorticoids on dynamic hyperinflation in moderate-to-severe asthma patients and explored the relationships between inflammatory markers and changes in dynamic hyperinflation.

Methods

In this randomised placebo-controlled trial we included 32 asthma patients on inhaled glucocorticoid therapy showing dynamic hyperinflation, defined by a ≥10% reduction in inspiratory capacity measured by standardised metronome-paced tachypnea test. Patients received either triamcinolone (80 mg) or placebo intramuscularly. Before and 2 weeks after treatment, patients completed respiratory health questionnaires, had blood eosinophils and exhaled nitric oxide levels measured, and underwent lung function and dynamic hyperinflation testing.

Results

After adjustment for potential confounders, dynamic hyperinflation was significantly reduced by 28.1% in the triamcinolone group and increased by 9.4% in the placebo group (p=0.027). In the triamcinolone-treated patients, the reduction in dynamic hyperinflation was greater in patients with higher blood eosinophils at baseline (r=−0.592, p=0.020) and tended to be associated with a reduction in blood eosinophils (r=0.412, p=0.127) and exhaled nitric oxide (r=0.442, p=0.099).

Conclusions

This exploratory study suggests that dynamic hyperinflation in asthma can be reduced by systemic anti-inflammatory treatment, particularly in patients with elevated blood eosinophils. This supports the hypothesis that dynamic hyperinflation in asthma is due to airway inflammation and should be considered an important target for treatment.

Dynamic hyperinflation: a target for treatment in asthma, which can be reduced by systemic anti-inflammatory treatmenthttps://bit.ly/3gfyxYv

Correlation study of cytokine levels in alveolar lavage fluid with exhaled nitric oxide and lung function in children with bronchial asthma

BACKGROUND

The associations between cytokines in the bronchoalveolar lavage fluid (BALF), lung cytokine expression, fractional exhaled nitric oxide (FeNO) and pulmonary function test results in pediatric asthmatics have not been extensively characterized. This study sought to explore correlations between cytokines BALF, FeNO, and pulmonary function test results.

METHODS

From October 2018 to October 2020, a prospective study was conducted on 42 children with asthma and 17 children with pulmonary foreign bodies that required bronchoscopy. Pulmonary function tests and FeNO tests were performed on all patients. Patients were divided into a high FeNO group or low FeNO group based on their FeNO results. Interleukin (IL)-4, IL-5, IL-6, IL-8, IL-13, and IL-17 in the BALF were measured by enzyme-linked immunosorbent assays. Pearson correlations were used to assess the correlations between the cytokines in BALF, the pulmonary function test results, and the FeNO results. Pearson correlation was used to calculate the correlation coefficient "r" among alveolar lavage fluid cytokines, lung function, and FeNO. Receiver operating characteristic (ROC) curves were used to determine the area under the curve (AUC), sensitivity, and specificity of BALF cytokines for the high and low FeNO groups.

RESULTS

IL-4, IL-5, IL-6, IL-8, IL-13, and IL-17 in BALF were significantly correlated with FeNO, but were not significantly correlated with the pulmonary function test results. Cytokine IL-4, IL-5, IL-6, IL-8, IL-13, and IL-17 in BALF were significantly different in the high FeNO, low FeNO, and control groups (all P<0.05). The AUCs for differentiating between low and high FeNO based on BALF cytokines ranged from 0.72 to 0.95. The sensitivity and specificity for discriminating between low and high FeNO based on IL-5 and IL-13 reached 95.7% and 100%, respectively.

CONCLUSIONS

The cytokine levels of the BALF of children with asthma were significantly elevated, correlated with FeNO, and can be used evaluate airway inflammation in children with asthma.

Seven Pillars of Small Airways Disease in Asthma and COPD: Supporting Opportunities for Novel Therapies

Identification of pathologic changes in early and mild obstructive lung disease has shown the importance of the small airways and their contribution to symptoms. Indeed, significant small airways dysfunction has been found prior to any overt airway obstruction being detectable by conventional spirometry techniques. However, most therapies for the treatment of obstructive lung disease target the physiological changes and associated symptoms that result from chronic lung disease, rather than directly targeting the specific underlying causes of airflow disruption or the drivers of disease progression. In addition, although spirometry is the current standard for diagnosis and monitoring of response to therapy, the most widely used measure, FEV1 , does not align with the pathologic changes in early or mild disease and may not align with symptoms or exacerbation frequency in the individual patient. Newer functional and imaging techniques allow more effective assessment of small airways dysfunction; however, significant gaps in our understanding remain. Improving our knowledge of the role of small airways dysfunction in early disease in the airways, along with the identification of novel end points to measure subclinical changes in this region (ie, those not captured as symptoms or identified through standard FEV1), may lead to the development of novel therapies that directly combat early airways disease processes with a view to slowing disease progression and reversing damage. This expert opinion paper discusses small airways disease in the context of asthma and COPD and highlights gaps in current knowledge that impede earlier identification of obstructive lung disease and the development and standardization of novel small airways-specific end points for use in clinical trials.

Enhanced alveo pulmonary deposition of nebulized ciclesonide for attenuating airways inflammations: a strategy to overcome metered dose inhaler drawbacks

Ciclesonide (CIC), an inhaled corticosteroid for bronchial asthma is currently available as metered dose inhaler (CIC–MDI) which possesses a major challenge in the management of the elderly, critically ill patients and children. In this work, nebulized CIC nano-structure lipid particles (CIC-NLPs) were prepared and evaluated for their deep pulmonary delivery and cytotoxicity to provide additional clinical benefits to patients in controlled manner and lower dose. The bio-efficacy following nebulization in ovalbumin (OVA) induced asthma Balb/c mice compared to commercial (CIC–MDI) was also assessed. The developed NLPs of 222.6 nm successfully entrapped CIC (entrapment efficiency 93.3%) and exhibited favorable aerosolization efficiency (mass median aerodynamic diameter (MMAD) 2.03 μm and fine particle fraction (FPF) of 84.51%) at lower impactor stages indicating deep lung deposition without imparting any cytotoxic effect up to a concentration of 100 μg/ml. The nebulization of 40 µg dose of the developed CIC-NLPs revealed significant therapeutic impact in the mitigation of the allergic airways inflammations when compared to 80 µg dose of the commercial CIC–MDI inhaler (Alvesco^®). Superior anti-inflammatory and antioxidative stress effects characterized by significant decrease (p< .0001) in inflammatory cytokines IL-4 and 13, serum IgE levels, malondialdehyde (MDA), nitric oxide (NO), TNF-α, and activated nuclear factor-κB (NF-κB) activity were obvious with concomitant increase in superoxide dismutase (SOD) activity. Histological examination with inhibition of inflammatory cell infiltration in the respiratory tract was correlated well with observed biochemical improvement.

Clinical Values of Nitric Oxide Parameters from the Respiratory System

BACKGROUND

Fractional exhaled nitric oxide (FENO) concentration reliably reflects central airway inflammation, but it is not sensitive to changes in the NO dynamics in the lung periphery. By measuring FENO at several different flow rates one can estimate alveolar NO concentration (C_ANO), bronchial NO flux (J_awNO), bronchial wall NO concentration (C_awNO) and the bronchial diffusivity of NO (D_awNO).

OBJECTIVE

We aimed to describe the current knowledge and clinical relevance of NO parameters in different pulmonary diseases.

METHODS

We conducted a systematic literature search to identify publications reporting NO parameters in subjects with pulmonary or systemic diseases affecting the respiratory tract. A narrative review was created for those with clinical relevance.

RESULTS

Estimation of pulmonary NO parameters allows for differentiation between central and peripheral inflammation and a more precise analysis of central airway NO output. C_ANO seems to be a promising marker of parenchymal inflammation in interstitial lung diseases and also a marker of tissue damage and altered gas diffusion in chronic obstructive pulmonary disease and systemic diseases affecting the lung. In asthma, C_ANO can detect small airway involvement left undetected by ordinary FENO measurement. Additionally, C_awNO and D_awNO can be used in asthma to assess if FENO is increased due to enhanced inflammatory activity (increased C_awNO) or tissue changes related to bronchial remodelling (altered D_awNO).

CONCLUSION

NO parameters may be useful for diagnosis, prediction of disease progression and prediction of treatment responses in different parenchymal lung and airway diseases. Formal trials to test the added clinical value of NO parameters are needed.

Onset of action of inhaled glucocorticoids on bronchial and alveolar nitric oxide output

Fractional exhaled nitric oxide (F_ENO) is a marker of airway inflammation. Measuring F_ENO at multiple flow rates enables calculation of NO parameters: bronchial NO output (J _awNO), bronchial wall (C _awNO) and alveolar (C _ANO) NO concentrations, and bronchial diffusion factor of NO (D _awNO). F_ENO is known to rapidly reduce after the commencement of inhaled corticosteroid (ICS) treatment. However, little is known on the effect of ICS on the other NO parameters. We assessed (1) the onset of action of ICS treatment on the NO parameters and (2) whether the changes in bronchial NO output are due to changes in bronchial wall NO concentration or diffusion factor. F_ENO and other NO parameters were measured at baseline and after 1, 3 and 7 d of treatment with inhaled fluticasone propionate 250 μg b.i.d. in 23 allergic children with a history of asthma-like symptoms. There was a decrease in J _awNO (from 680 (244/1791) (median (1st/3rd quartile)) to 357 (165/753) pl s^-1, p < 0.001) and F_ENO₅₀( from 13.8 (7.5/35) to 8.3 (5.36/17.0) ppb, p < 0.001) in 3 d from the first dose of ICS. Also, C _awNO seemed to reduce after 3 d (from 171 (89/328) to 79 (54/157) ppb, p = 0.041), while D _awNO remained unchanged. Furthermore, C _ANO reduced during the 7 d treatment (from 3.0 (2.0/5.0) to 2.3 (1.9/2.6) ppb, p = 0.004). ICS treatment reduced F_ENO₅₀ and J _awNO rapidly and the decline was caused by decreased bronchial wall NO concentration while bronchial NO diffusion factor remained unchanged. These findings suggest that C _awNO could be a more specific marker of airway inflammation and treatment response than J _awNO or F_ENO₅₀, which are both determined also by D _awNO that seems to be resistant to the treatment with ICS.

The effects of oral corticosteroids on lung function, type-2 biomarkers and patient-reported outcomes in stable asthma: A systematic review and meta-analysis

BACKGROUND

Several studies have investigated the physiological effect of OCS in stable asthma, however these have included heterogeneous populations and outcomes. This paper is the first to combine their results.

METHODS

We searched Medline, Embase and Web of Science databases for studies reporting the impact of OCS on FEV₁, FVC, blood eosinophils, fractional exhaled nitric oxide (FeNO), Asthma Control Questionnaire (ACQ) score or Asthma Quality Of Life Questionnaire (AQLQ) score in stable asthma. We extracted data on the correlates of OCS response.

RESULTS

61 studies, comprising 1608 patients, were included. FEV₁ was improved by 9% (95% CI: 7, 11). There were stronger increases in FEV₁ among those with a mean baseline FEV₁<60% predicted (19%, 95% CI: 13, 24). Despite these improvements, substantial residual impairment remained after treatment. Blood eosinophils were reduced by 76% (95% CI: 63, 88) with larger decreases in studies of corticosteroid-naïve patients (93%, 95% CI: 73,100). Sputum eosinophils were reduced by 89% (95% CI: 79, 98) while FeNO was decreased by 35% (95% CI: 28, 41). ACQ scores were reduced by 20% (95% CI: 11, 29). Patients with higher baseline lung function impairment, sputum eosinophils, blood eosinophils and FeNO had improved OCS response.

INTERPRETATION

OCS consistently improves lung function, reduces markers of type-2 inflammation, and alleviates asthma symptoms. However, substantial residual impairment remained following treatment and mean improvements were below the minimally important clinically difference. Patients with increased markers of type-2 inflammation are more responsive to treatment, suggesting these should be used to better target OCS use.

Relationship between opiates and asthma in the determination of death

Several studies have shown an association between asthma and opiate abuse. This retrospective study aims to analyse the demographic, toxicological, and seasonal differences in asthmatic and non-asthmatic subjects who died of opiates. In addition, the relationship between toxicological levels of opiates and histologic grade of lung inflammation is examined. Deaths from 2013 to 2018 involving opiates as the primary cause of death in Cook County, Illinois (USA) were reviewed. Twenty-six cases of opiate deaths of individuals with a history of asthma and lung histology slides available were identified. In comparison, 40 cases of deaths due to opiates only were analysed. A check-list system for the evaluation of the grade of microscopic inflammation in asthma was developed. We found statistically significant differences between the asthmatics and the non-asthmatics regarding demography (age and race) and toxicology (6-MAM presence). In particular, the "opiate and asthma group" was mainly composed of African-American subjects, in contrast with the "opiate group", consisting mostly of Caucasian. The mean age was significantly higher in the "opiate and asthma group" compared with the "opiate group". A greater presence of 6-MAM was detected in the "opiate group" compared with the "opiate and asthma group". While we expected to find that low opiate levels would lead to deaths in asthmatics and, in particular, that lower opiate concentrations would cause deaths in subjects with higher grades of histologic inflammation, our study suggests that the quantity of drug and the level of inflammation are not statistically significant in the determination of death. We, therefore, recommend histologic examination of the lungs to evaluate for asthma, particularly in suspected low-level opiate-related deaths, to help further clarify any relationship between asthma and opiate use.

Study of the role of exhaled nitric oxide (NO) in predicting controlled or uncontrolled asthma in asthmatic children

Background

Exhaled nitric oxide (NO), especially fractional concentration of exhaled NO (FE_NO) has been used to predict the responsiveness to inhaled corticosteroid (ICS) in children with asthma. However, the use of exhaled NO for predicting asthma control in children is still controversial.

Methods

This was a perspective observational study. Asthmatic children who were naïve to inhaled corticosteroid (ICS) were included in the present study. The measurements of FE_NO and CA_NO (concentration of NO in the gas phase of the alveolar), spirometry, blood eosinophil counts (BEC), and total IgE levels were done for each asthmatic child. All study subjects started proper asthma treatment after the enrollment.

Results

Ninety three asthmatic children (9±3 years) with moderate (63.4%) to severe (36.6%) asthma were included and finished the 3-month study. The levels of FE_NO and CA_NO at inclusion were 37±11 ppb and 5.8±1.4 ppb, respectively; the mean of BEC was 617±258 cells/μL; the level of total IgE was 1563±576 UI/mL; 89% of subjects were positive for at least one respiratory allergen. The percentage of severe asthma was reduced significantly after 3 months (P<0.001). Well controlled asthma subjects at 3 months had higher levels of FE_NO and lower levels of CA_NO at inclusion (P<0.05 and P<0.05). FE_NO<20 ppb or CA_NO>5ppb had a risk of uncontrolled asthma at 3 months (OR: 1.7, CI 95% [(0.8) - (3.3)], P<0.05; OR: 1.9, CI 95% [(0.9) - (2.7)], P<0.05; respectively). FE_NO>35 ppb at inclusion had a positive predictive value for asthma control at 3 months (OR: 3.5, CI 95% [2.2-5.9], P<0.01).

Conclusions

Exhaled NO is a biomarker of asthma which may have a potential role to predict the control of asthma in short-term follow up in asthmatic children.

Evaluation of Interleukin-6, Leukotriene B-4, and Nitric Oxide Levels in Exhaled Breath Condensate of Asymptomatic Obese Individuals: Are Obese Patients Under Risk of Developing Asthma?

Objective

If systemic inflammation in relation with obesity causes asthma, the detection of increased airway inflammation among obese individuals who do not have any respiratory symptoms can be also beneficial in indentifying obese patients who are at risk of developing asthma. The aim of this study was to evaluate the systemic and airway inflammation of asymptomatic obese and non-obese individuals.

Materials and Methods

Obese and non-obese individuals with no respiratory symptoms were included. Inflammatory biomarkers such as C-reactive protein (CRP), exhaled breath condensate (EBC) interleukin-6 (IL-6), EBC leukotriene B-4 (LTB-4), and EBC nitric oxide (NO) levels of obese and non-obese individuals were determined.

Results

Forty-five obese individuals (body mass index [BMI]≥30) and 31 non-obese individuals (BMI≤25) as a control group were included in this study. The mean age of the obese group (38.7±11.4 years) was significantly higher than the one of the non-obese group (29.5±8.6 years; p<0.001). There was no significant relationship between gender and BMI (χ² =1.471, p=0.225). CRP levels were significantly higher in the obese group (6.94±8.28) than the non-obese group (3.29±0.39; p<0.001). The levels of EBC IL-6 in obese and non-obese group were found as 22.61±12.53 and 21.08±14.39, respectively (p=0.624). There was no significant difference between EBC NO levels of the obese group and non-obese group (24.35±10.9 vs. 21.56±7.83; p=0.226). No significant difference was found between the EBC LTB-4 level in the obese group and the non-obese group (36.39±89.82 vs. 16.64±17.45; p=0.231).

Conclusion

Increased systemic inflammation in obese individuals who had no respiratory symptoms might indicate the tendency of asthma. However, airway inflammation was not significantly different between groups. Therefore the relationship between obesity and asthma should be investigated in future large-scale studies determining the direct effects of adipokines on airways.

A Role for Alveolar Exhaled Nitric Oxide Measurement in the Diagnosis of Hepatopulmonary Syndrome

GOALS

The authors sought to characterize predominantly alveolar exhaled nitric oxide (eNO) in hepatopulmonary syndrome (HPS) compared with non-HPS, changes after liver transplantation, and diagnostic properties.

BACKGROUND

HPS is defined by liver disease, intrapulmonary vascular dilatations (IPVDs), and hypoxemia. Rat models and small human studies suggest that NO overproduction may cause IPVDs.

STUDY

A retrospective review of the Canadian HPS Database (2007 to 2017) and prospective eNO measurement (main outcome) in healthy controls (measurement expiratory flow, 200 mL/s). HPS was defined as: (1) liver disease; (2) contrast echocardiography consistent with IPVDs; and (3) partial pressure of arterial oxygen <70 mm Hg with alveolar-arterial gradient >20 mm Hg; subclinical HPS as criteria (1) and (2) only; and no HPS as criterion (1) only. Current smokers and subjects with asthma or pulmonary hypertension were excluded. A linear mixed effects model was used to compare eNO between groups and before and after transplantation.

RESULTS

eNO was 10.4±0.7 ppb in HPS (n=26); 8.3±0.6 ppb in subclinical HPS (n=38); 7.1±1.0 ppb in no HPS (n=15); and 5.6±0.7 ppb in controls (n=30) (P<0.001). eNO decreased from 10.9±0.8 ppb preliver to 6.3±0.8 ppb postliver transplant (n=6 HPS, 6 subclinical HPS) (P<0.001). eNO <6 ppb was 84.4% (73.1% to 92.2%) sensitive and ≥12 ppb was 78.1% (69.4% to 85.3%) specific for HPS (vs. subclinical HPS).

CONCLUSIONS

HPS subjects have higher alveolar eNO than non-HPS subjects, levels normalize with liver transplantation. Applying eNO cutoff values may aid in HPS diagnosis.

Repeatability and variation of the flow independent nitric oxide parameters

INTRODUCTION

Fractional exhaled nitric oxide (F_ENO) is a non-invasive marker of airway inflammation. Measuring F_ENO at several flow rates enables the calculation of flow independent NO-parameters (alveolar NO concentration (C_ANO), bronchial flux of NO (J_awNO), bronchial mucosal NO concentration (C_awNO) and bronchial wall NO diffusion capacity (D_awNO)) that are capable of partitioning the source and release mechanism of NO from the lower respiratory tract. However, the current literature on repeatability and normal variation of the NO-parameters is deficient, and this information is needed to develop the method towards clinical use.

METHODS

We calculated NO-parameters in 28 healthy subjects using two different mathematical methods and used three different study protocols to investigate: (i) repeatability of two consecutive measurements of NO-parameters, (ii) within-day variation of the NO-parameters over one working day and (iii) day-to-day variation of the NO-parameters between consecutive days during course of a working week.

RESULTS

J_awNO was the most repeatable among the NO-parameters, whereas D_awNO and C_awNO were notably least repeatable. C_ANO was higher during the second consecutive measurement (1.22 versus 1.57 ppb, p = 0.017). Both investigated mathematical methods yielded equally repeatable results. J_awNO was slightly higher in the afternoon compared to morning (716 versus 881 pl/s, p = 0.01), but other parameters showed no diurnal variation. Upper 95% limit for the day-to-day difference in the parameters in healthy subjects was about 1.2 ppb in C_ANO, 400 pl/s in J_awNO, 92 ppb in C_awNO and 16 pl/s/ppb in D_awNO.

CONCLUSIONS

This is the first study assessing short-time repeatability of the NO-parameters. Repeatability of the NO-parameters was good and day-to-day variation in NO-parameters was quite low. We recommend scheduling F_ENO-measurements at the same time of day, if possible, and in clinical use variation in NO-parameters above the normal limits found in this study suggest changes in the disease's activity.

Oral corticosteroid-dependent asthma: current knowledge and future needs

PURPOSE OF REVIEW

To discuss the current use of oral corticosteroids (OCS) as a chronic treatment in patients with severe asthma and as a rescue treatment for patients presenting with acute exacerbations.

RECENT FINDINGS

Airways disease is responsible for the bulk of OCS use in the community and considerable OCS-associated morbidity. I speculate that the key mechanism leading to a beneficial effect in these situations is depletion of circulating eosinophils resulting in a reduced response to potentially inhaled corticosteroid unresponsive recruitment signals to the airway mucosa. This effect is shared by anti-IL-5 biological agents, which have emerged as highly effective OCS-sparing agents. Mitigation of the adverse effects of OCS might also result from a better appreciation of features associated with a response to OCS and targeted, biomarker-directed use.

SUMMARY

Longer term, there are real prospects that chronic and acute OCS use in asthma will be replaced by biological agents targeting eosinophilic airway inflammation more specifically and safely.

Elevated Levels of Alveolar Nitric Oxide May Indicate Presence of Small Airway Inflammation in Patients with Inflammatory Bowel Disease

INTRODUCTION

Pulmonary manifestations of inflammatory bowel disease (IBD), albeit not rare, are largely overlooked in clinical practice. The role of exhaled nitric oxide (eNO) as an established biological marker of airway inflammation compels us to use it as a tool to investigate the exact nature of these manifestations.

METHODS

Fractional eNO (FeNO) was measured in multiple flows, and with the use of a mathematical model, alveolar concentration of NO (CANO) and bronchial flux of NO (JawNO) were assessed in 27 patients with IBD [17 with Crohn's disease (CD) and 10 with ulcerative colitis (UC)] and in 39 healthy controls. Carefully selected criteria were used to exclude patients or healthy controls that presented factors considered to be correlated with eNO measurements. Disease activity was measured in Crohn's patients using the CD activity index (CDAI) score and in UC using the partial Mayo score.

RESULTS

CANO was significantly higher in the IBD group, compared to the control group (p < 0.0001). FeNO was significantly increased in patients with IBD (p = 0.023), while there was no statistical significance found regarding levels of JawNO in patients with IBD (p = 0.106), both compared to controls. There was no significant correlation between any eNO component and markers of disease activity.

CONCLUSIONS

Alveolar concentration of NO is elevated in patients with IBD, regardless of disease activity. This may suggest that subclinical small airway inflammation is present in patients with IBD, even those with mild or inactive disease.

Flow-independent nitric oxide parameters in asthma: a systematic review and meta-analysis

INTRODUCTION

Fractional exhaled nitric oxide (F_ENO) has been proposed as a non-invasive marker of inflammation in the lungs. Measuring F_ENO at several flow rates enables the calculation of flow independent NO-parameters that describe the NO-exchange dynamics of the lungs more precisely. The purpose of this study was to compare the NO-parameters between asthmatics and healthy subjects in a systematic review and meta-analysis.

METHODS

A systematic search was performed in Ovid Medline, Web of Science, Scopus and Cochrane Library databases. All studies with asthmatic and healthy control groups with at least one NO-parameter calculated were included.

RESULTS

From 1137 identified studies, 33 were included in the meta-analysis. All NO-parameters (alveolar NO concentration (C_ANO), bronchial flux of NO (J_awNO), bronchial mucosal NO concentration (C_awNO) and bronchial wall NO diffusion capacity (D_awNO)) were found increased in glucocorticoid-treated and glucocorticoid-naïve asthma. J_awNO and C_ANO were most notably increased in both study groups. Elevation of D_awNO and C_awNO seemed less prominent in both asthma groups.

DISCUSSION

We found that all the NO-parameters are elevated in asthma as compared to healthy subjects. However, results were highly heterogenous and the evidence on C_awNO and D_awNO is still quite feeble due to only few studies reporting them. To gain more knowledge on the NO-parameters in asthma, nonlinear methods and standardized study protocols should be used in future studies.

Small airway inflammation is associated with residual airway hyperresponsiveness in Th2-high asthma

Background: Asthma is characterized by airway inflammation, variable airflow obstruction, and airway hyperresponsiveness (AHR). Generally, AHR takes longer to resolve than does airflow obstruction or clinical symptoms. AHR occasionally persists despite adequate asthma treatment.Objective: To evaluate factors which associates with residual AHR in patients with seemingly remitted airway inflammation.Methods: Patients who exhibited high fractional exhaled nitric oxide (FeNO) levels (>25 ppb) at the first visit (Visit 1) and normalized FeNO levels (<25 ppb) after adequate asthma treatment, including inhaled corticosteroid administration (Visit 2), were analyzed. Patients underwent a blood test, FeNO and small airway/alveolar nitric oxide concentration (CANO) measurements and a methacholine challenge test (continuous inhalation method) at both visits. Clinical indices were compared between patients with and without residual AHR.Results: Fifty patients were analyzed. All exhibited high FeNO levels at Visit 1 [mean, 54.0 ppb (95% confidence interval, 42.4-65.5)] and improvement of FeNO levels at Visit 2 [20.4 (19.2-21.6)] (p < 0.0001). Thirty-three patients (66%) had remission of AHR at Visit 2. No significant differences were observed between patients with and without residual AHR in terms of FeNO levels, lung function parameters and blood eosinophil counts at both visits. CANO level at Visit 2 was the only factor that significantly differed between patients with residual AHR [2.7 (1.9-3.6)] and those who achieved AHR remission [0.8 (0.5-1.0)] (p < 0.0001).Conclusion: Small airway inflammation, as assessed by CANO, was associated with residual AHR in patients with Th2-high asthma.

Fractional exhaled nitric oxide was not associated with the future risk of exacerbations in Chinese asthmatics: a non-interventional 1-year real-world study

Background

Exacerbations are recognized as the most relevant predictor of future risk in asthmatics. We aimed to evaluate the association between asthma exacerbations, fractional exhaled nitric oxide (FENO), spirometry indices, and other potential risk factors in a non-interventional, real-world study performed in Guangzhou, China.

Methods

We performed a prospective 12 months follow-up of Chinese asthmatics. Spirometry and FENO measurements were performed at baseline. Adherence to inhaled corticosteroids (ICS) use was divided into two categories (>80% and <80%). Patients were seen 4 times after the initial baseline visit.

Results

A total of 222 patients with asthma (49.1% males) completed the study, of which 51 (23.0%) experienced exacerbations during the study period. Of the patients, 117 (52.7%) had good compliance. We compared lung function indices between the patients with and without exacerbations. There was no difference of forced expiratory volume in 1 s (FEV1) predicted, forced vital capacity (FVC) predicted, and FEVI/FVC (all, P>0.05) between the groups. There was also no significant difference in FENO level between the two groups. Compared to those that had exacerbations, patients without exacerbations had better treatment compliance (P<0.001). Logistic regression analysis identified an association between asthma exacerbations, poor control of symptom [odds ratio (OR) =2.295; 95% confidence interval (CI): 1.130-4.663; P=0.022], and nonadherence to asthma medications (OR =4.718; 95% CI: 2.149-10.359; P<0.001).

Conclusions

Poor adherence rather than baseline FENO and FEV1% predicted was associated with the future risk of exacerbations in Chinese asthmatics in real world.

Recent Advances in Inflammation and Treatment of Small Airways in Asthma

Small airways were historically considered to be almost irrelevant in the development and control of pulmonary chronic diseases but, as a matter of fact, in the past few years we have learned that they are not so "silent". Asthma is still a worldwide health issue due to the great share of patients being far from optimal management. Several studies have shown that the deeper lung inflammation plays a critical role in asthma pathogenesis, mostly in these not well-controlled subjects. Therefore, assessing the degree of small airways inflammation and impairment appears to be a pivotal step in the asthmatic patient's management. It is now possible to evaluate them through direct and indirect measurements, even if some obstacles still affect their clinical application. The success of any treatment obviously depends on several factors but reaching the deeper lung has become a priority and, for inhaled drugs, this is strictly connected to the molecule's size. The aim of the present review is to summarize the recent evidence concerning the small airway involvement in asthma, its physiopathological characteristics and how it can be evaluated in order to undertake a personalized pharmacological treatment and achieve a better disease control.

Measuring lung function in airways diseases: current and emerging techniques

Chronic airways diseases, including asthma, COPD and cystic fibrosis, cause significant morbidity and mortality and are associated with high healthcare expenditure, in the UK and worldwide. For patients with these conditions, improvements in clinical outcomes are likely to depend on the application of precision medicine, that is, the matching of the right treatment to the right patient at the right time. In this context, the identification and targeting of 'treatable traits' is an important priority in airways disease, both to ensure the appropriate use of existing treatments and to facilitate the development of new disease-modifying therapy. This requires not only better understanding of airway pathophysiology but also an enhanced ability to make physiological measurements of disease activity and lung function and, if we are to impact on the natural history of these diseases, reliable measures in early disease. In this article, we outline some of the key challenges faced by the respiratory community in the management of airways diseases, including early diagnosis, disease stratification and monitoring of therapeutic response. In this context, we review the advantages and limitations of routine physiological measurements of respiratory function including spirometry, body plethysmography and diffusing capacity and discuss less widely used methods such as forced oscillometry, inert gas washout and the multiple inert gas elimination technique. Finally, we highlight emerging technologies including imaging methods such as quantitative CT and hyperpolarised gas MRI as well as quantification of lung inhomogeneity using precise in-airway gas analysis and mathematical modelling. These emerging techniques have the potential to enhance existing measures in the assessment of airways diseases, may be particularly valuable in early disease, and should facilitate the efforts to deliver precision respiratory medicine.

Dynamic hyperinflation impairs daily life activity in asthma

INTRODUCTION

Dynamic hyperinflation has been documented in asthma, yet its impact on overall health and daily life activities is unclear. We assessed the prevalence of dynamic hyperinflation in moderate to severe asthma and its relationship with the scores of a set of specific and general respiratory health questionnaires.

METHODS

77 nonsmoking asthma patients (Global Initiative for Asthma steps 4-5) were recruited consecutively and completed five questionnaires: Asthma Control Questionnaire, Clinical COPD (chronic obstructive pulmonary disease) Questionnaire, St George's Respiratory Questionnaire, London Chest Activity of Daily Living scale (LCADL) and Shortness of Breath with Daily Activities (SOBDA). Dynamic hyperinflation was defined as ≥10% reduction in inspiratory capacity induced by standardised metronome-paced tachypnoea. Associations between level of dynamic hyperinflation and questionnaire scores were assessed and adjusted for asthma severity.

RESULTS

81% (95% CI 71.7-89.4%) of patients showed dynamic hyperinflation. Higher levels of dynamic hyperinflation were related to poorer scores on all questionnaires (r=0.228-0.385, p<0.05). After adjustment for asthma severity, dynamic hyperinflation remained associated with poorer scores on LCADL (p=0.027) and SOBDA (p=0.031).

CONCLUSION

Dynamic hyperinflation is associated with poorer overall health and impaired daily life activities, independent of asthma severity. Because of its major impact on everyday life activities, dynamic hyperinflation is an important target for treatment in asthma.

Comparison of inducible nitric oxide synthase mRNA expression in different airway portions and association with nitric oxide parameters from patients with asthma

Background

Fractional exhaled nitric oxide concentration (FeNO) is widely used to support diagnosis and monitoring of bronchial asthma (BA). Tsoukias and George proposed a two‐compartment model (2CM) for assessing the alveolar concentration of NO, referred to as CANO(2CM), while Condorelli et al proposed a model based on the trumpet shape of the airway tree and axial diffusion (TMAD), referred to as CANO(TMAD). In addition, Högman et al proposed non‐linear model, referred to as CANO(non‐linear).

Objective

We examined associations between the expression of inducible nitric oxide synthase (iNOS) mRNA in airway cells (ACs) by bronchoscopy and NO‐parameters calculated by the three methods and identified which of them accurately reflected expression of iNOSmRNA from different airway portions.

Methods

We retrospectively analysed data of 18 patients with stable, mild‐moderate asthma, including 10 steroid‐naïve BA (snBA) patients. Samples were obtained from airway brushings and bronchoalveolar lavage (BAL). Expressions of iNOS protein in tissue samples were evaluated by immunostaining. The iNOSmRNA in ACs was measured by qPCR. NO‐parameters calculated by the three methods above and evaluated whether they were associated with iNOSmRNA in ACs derived from proximal (2nd carina), distal (10‐15th) airways and alveolar regions.

Results

Immunostaining revealed expression of iNOS proteins mainly in epithelial cells in the airways, while it was mainly expressed in macrophages in the alveolar region in the snBA group. The iNOSmRNA expression was increased in both proximal and distal ACs in the snBA group compared with steroid‐treated BA group (stBA). CANO(2CM) negatively associated with FEV₁ (%predicted) and also associated with iNOSmRNA in distal ACs significantly. However, CANO(TMAD) and CANO(non‐linear) showed no correlation with lung function nor iNOSmRNA expression in any portions of ACs.

Conclusions

These results suggested that CANO(2CM) reflected distal airway inflammation in steroid‐naïve asthma.

Use of computational fluid dynamics deposition modeling in respiratory drug delivery

INTRODUCTION

Respiratory drug delivery is a surprisingly complex process with a number of physical and biological challenges. Computational fluid dynamics (CFD) is a scientific simulation technique that is capable of providing spatially and temporally resolved predictions of many aspects related to respiratory drug delivery from initial aerosol formation through respiratory cellular drug absorption.

AREAS COVERED

This review article focuses on CFD-based deposition modeling applied to pharmaceutical aerosols. Areas covered include the development of new complete-airway CFD deposition models and the application of these models to develop a next-generation of respiratory drug delivery strategies.

EXPERT OPINION

Complete-airway deposition modeling is a valuable research tool that can improve our understanding of pharmaceutical aerosol delivery and is already supporting medical hypotheses, such as the expected under-treatment of the small airways in asthma. These complete-airway models are also being used to advance next-generation aerosol delivery strategies, like controlled condensational growth. We envision future applications of CFD deposition modeling to reduce the need for human subject testing in developing new devices and formulations, to help establish bioequivalence for the accelerated approval of generic inhalers, and to provide valuable new insights related to drug dissolution and clearance leading to microdosimetry maps of drug absorption.

A suitable protocol for measuring alveolar nitric oxide in asthma with differing severity to assess peripheral airways inflammation

OBJECTIVE

Extended nitric oxide (NO) analysis offers the partitioned monitoring of inflammation in central and peripheral airways. Different mathematical models are used to estimate pulmonary NO dynamics in asthma with variable results and limitations. We aimed to establish a protocol for extended NO analysis in patients with differing asthma severity.

METHODS

Forty patients with stable asthma and 25 matched control subjects were recruited. Exhaled NO was measured at constant flow rates between 10 and 300 mL/s. Twelve controls performed NO measurements weekly for 4 weeks.

RESULTS

The proportions of patients with technically acceptable measurements at 10-30-50-100-150-200-250-300 mL/s exhalation flow rates were 8-58-100-98-98-95-90-80%, respectively. Alveolar NO (CANO) and total flux of NO in the conducting airways (JawNO) were calculated with the linear method from NO values measured at 100-150-200-250 mL/s exhalation flows. The mean intrasubject bias for JawNO and CANO in controls was 0.16 nL/s and 0.85 ppb, respectively. Both JawNO (1.31/0.83-2.97/vs. 0.70/0.54-0.87/nL/s, p < 0.001) and CANO (4.08/2.63-7.16/vs. 2.42/1.83-2.89/ppb, p < 0.001) were increased in patients with asthma compared to controls. In patients, CANO correlated with RV/TLC (r = 0.58, p < 0.001), FEF_25-75% (p = 0.02, r = -0.36) and DL,CO (r = -0.46, p = 0.004). JawNO was not related to lung function parameters.

CONCLUSIONS

Calculation of alveolar NO concentration with the linear method from values obtained at medium flow rates (100-250 mL/s) is feasible even in asthmatic patients with severe airflow limitation and may provide information on small airways dysfunction in asthma.

Protective effect of water extract of guibi-tang against pulmonary inflammation induced by cigarette smoke and lipopolysaccharide

Water extract of guibi-tang (GB), a traditional Chinese, Japanese, and Korean herbal medicine, is used to treat memory impairment, insomnia, and peptic ulcers. The aim of this study was to investigate the protective effects of GB on pulmonary inflammation induced by cigarette smoke (CS) and lipopolysaccharide (LPS). C57BL/6 mice were used to develop a pulmonary inflammation model by exposing them to CS for 1 h per day for 7 days. LPS was intranasally administered to mice under mild anesthesia on day 5. GB was administered 1 h before CS exposure at doses of 50 or 100 mg/kg for 7 days. Our results showed that GB suppressed the CS and LPS induced elevation in inflammatory cell counts in the bronchoalveolar lavage fluid (BALF), with significant reductions in protein, tumor necrosis factor (TNF)-α, and interleukin (IL)-6 levels. Histological studies revealed that GB decreased the inflammatory cell infiltration into lung tissue caused by CS- and LPS-exposure. GB also significantly decreased the CS and LPS-induced expression of inducible nitric oxide synthase (iNOS) in the lung tissue. Taken together, GB effectively attenuated airway inflammation caused by CS and LPS. These results indicate that GB is a potential therapeutic herbal formula for pulmonary inflammatory disease.

Role of Small Airways in Asthma

Asthma is an inflammatory condition of both the small and large airways. Recently the small airways have gained attention as studies have shown significant inflammation in the small airways in all severities of asthma. This inflammation has correlated with peripheral airway resistance and as a result, noninvasive methods to reliably measure small airways have been pursued. In addition, recent changes in asthma inhalers have led to alterations in drug formulations and the development of extrafine particle inhalers that improve delivery to the distal airways.

Small Airway Absorption and Microdosimetry of Inhaled Corticosteroid Particles after Deposition

PURPOSE

To predict the cellular-level epithelial absorbed dose from deposited inhaled corticosteroid (ICS) particles in a model of an expanding and contracting small airway segment for different particle forms.

METHODS

A computational fluid dynamics (CFD)-based model of drug dissolution, absorption and clearance occurring in the surface liquid of a representative small airway generation (G13) was developed and used to evaluate epithelial dose for the same deposited drug mass of conventional microparticles, nanoaggregates and a true nanoaerosol. The ICS medications considered were budesonide (BD) and fluticasone propionate (FP). Within G13, total epithelial absorption efficiency (AE) and dose uniformity (microdosimetry) were evaluated.

RESULTS

Conventional microparticles resulted in very poor AE of FP (0.37%) and highly nonuniform epithelial absorption, such that <5% of cells received drug. Nanoaggregates improved AE of FP by a factor of 57-fold and improved dose delivery to reach approximately 40% of epithelial cells. True nanoaerosol resulted in near 100% AE for both drugs and more uniform drug delivery to all cells.

CONCLUSIONS

Current ICS therapies are absorbed by respiratory epithelial cells in a highly nonuniform manner that may partially explain poor clinical performance in the small airways. Both nanoaggregates and nanoaerosols can significantly improve ICS absorption efficiency and uniformity.

Inducible nitric oxide synthase expression is increased in the alveolar compartment of asthmatic patients

INTRODUCTION

Increased exhaled nitric oxide (NO) levels in asthma are suggested to be through inducible NO synthase (iNOS). The aim of this study was to investigate the expression of iNOS in bronchoalveolar lavage (BAL) cells and tissue from central and peripheral airways and compare it with the exhaled bronchial and alveolar NO levels in patients with asthma vs a control group.

METHODS

Thirty-two patients with asthma (defined as controlled or uncontrolled according to Asthma Control Test score cut-off: 20) and eight healthy controls were included. Exhaled NO was measured, and alveolar concentration and bronchial flux were calculated. iNOS was measured in central and peripheral lung biopsies, as well as BAL cells. Bronchoalveolar lavage macrophages were stimulated in vitro, and iNOS expression and NO production were investigated.

RESULTS

Expression of iNOS was increased in central airway tissue and the alveolar compartment in uncontrolled as compared to controlled asthmatics and healthy controls. There were no differences, however, in iNOS mRNA levels in total BAL cells in uncontrolled as compared to controlled asthma. Bronchoalveolar lavage cell mRNA levels of iNOS or iNOS expression in central and alveolar tissue did not relate to alveolar NO, nor to bronchial flux of NO. In vitro stimulation with leukotriene D₄ increased iNOS mRNA levels and NO production in cultured BAL macrophages.

CONCLUSION

The levels of both bronchial and alveolar iNOS are increased in uncontrolled as compared to controlled asthma. However, levels of iNOS in BAL macrophages were not reflected by alveolar NO. Both central and distal iNOS levels may reflect responsiveness to steroid treatment.

Utilising exhaled nitric oxide information to enhance diagnosis and therapy of respiratory disease - current evidence for clinical practice and proposals to improve the methodology

INTRODUCTION

A non-invasive tool to diagnose respiratory diseases and to follow treatment has long been looked-for. Exhaled nitric oxide (NO) is a promising marker of inflammation in asthma but nearly 25-years of research has shown that it works in only certain endotypes of asthma. The modelling of NO dynamics of the lung can give more information than a single F_ENO value. Areas covered: The estimation of the NO production in the conducting airways and in the gas exchange area has given new insight of the NO production in diseases beyond asthma. In this article, we discuss the importance of methodology for NO measurement in the exhaled breath and the indication of applying this technique to detect respiratory disorders. This narrative review is an attempt to examine and discuss the physiological basis underlying exhaled NO measurements and the clinical evidence of the usefulness of this method in asthma and various other respiratory disorders. Expert commentary: Estimation of the NO parameters would aid in our understanding of the NO dynamics of the lung and thereby give more knowledge how to interpret the measured F_ENO value in clinical practice.

Manifesto on small airway involvement and management in asthma and chronic obstructive pulmonary disease: an Interasma (Global Asthma Association - GAA) and World Allergy Organization (WAO) document endorsed by Allergic Rhinitis and its Impact on Asthma (ARIA) and Global Allergy and Asthma European Network (GA2LEN)

Evidence that enables us to identify, assess, and access the small airways in asthma and chronic obstructive pulmonary disease (COPD) has led INTERASMA (Global Asthma Association) and WAO to take a position on the role of the small airways in these diseases.

Starting from an extensive literature review, both organizations developed, discussed, and approved the manifesto, which was subsequently approved and endorsed by the chairs of ARIA and GA²LEN. The manifesto describes the evidence gathered to date and defines and proposes issues on small airway involvement and management in asthma and COPD with the aim of challenging assumptions, fostering commitment, and bringing about change.

The small airways (defined as those with an internal diameter <2 mm) are involved in the pathogenesis of asthma and COPD and are the major determinant of airflow obstruction in these diseases. Various tests are available for the assessment of the small airways, and their results must be integrated to confirm a diagnosis of small airway dysfunction.

In asthma and COPD, the small airways play a key role in attempts to achieve disease control and better outcomes. Small-particle inhaled formulations (defined as those that, owing to their size [usually <2 μm], ensure more extensive deposition in the lung periphery than large molecules) have proved beneficial in patients with asthma and COPD, especially those in whom small airway involvement is predominant.

Functional and biological tools capable of accurately assessing the lung periphery and more intensive use of currently available tools are necessary. In patients with suspected COPD or asthma, small airway involvement must be assessed using currently available tools. In patients with subotpimal disease control and/or functional or biological signs of disease activity, the role of small airway involvement should be assessed and treatment tailored. Therefore, the choice between large- and small-particle inhaled formulations must reflect the physician’s considerations of disease features, phenotype, and response to previous therapy.

This article is being co-published in Asthma Research and Practice and the World Allergy Organization Journal.

Manifesto on small airway involvement and management in asthma and chronic obstructive pulmonary disease: an Interasma (Global Asthma Association - GAA) and World Allergy Organization (WAO) document endorsed by Allergic Rhinitis and its Impact on Asthma (ARIA) and Global Allergy and Asthma European Network (GA2LEN)

Evidence that enables us to identify, assess, and access the small airways in asthma and chronic obstructive pulmonary disease (COPD) has led INTERASMA (Global Asthma Association) and WAO to take a position on the role of the small airways in these diseases.

Starting from an extensive literature review, both organizations developed, discussed, and approved the manifesto, which was subsequently approved and endorsed by the chairs of ARIA and GA²LEN. The manifesto describes the evidence gathered to date and defines and proposes issues on small airway involvement and management in asthma and COPD with the aim of challenging assumptions, fostering commitment, and bringing about change.

The small airways (defined as those with an internal diameter <2 mm) are involved in the pathogenesis of asthma and COPD and are the major determinant of airflow obstruction in these diseases. Various tests are available for the assessment of the small airways, and their results must be integrated to confirm a diagnosis of small airway dysfunction.

In asthma and COPD, the small airways play a key role in attempts to achieve disease control and better outcomes. Small-particle inhaled formulations (defined as those that, owing to their size [usually <2 μm], ensure more extensive deposition in the lung periphery than large molecules) have proved beneficial in patients with asthma and COPD, especially those in whom small airway involvement is predominant.

Functional and biological tools capable of accurately assessing the lung periphery and more intensive use of currently available tools are necessary. In patients with suspected COPD or asthma, small airway involvement must be assessed using currently available tools. In patients with subotpimal disease control and/or functional or biological signs of disease activity, the role of small airway involvement should be assessed and treatment tailored. Therefore, the choice between large- and small-particle inhaled formulations must reflect the physician’s considerations of disease features, phenotype, and response to previous therapy. This article is being co-published in Asthma Research and Practice and the World Allergy Organization Journal.

Induced sputum supernatant bioactive lipid mediators can identify subtypes of asthma

BACKGROUND

Induced sputum (IS) allows to measure mediators of asthmatic inflammation in bronchial secretions. The specific role of induced sputum supernatant (ISS) endogenous bioactive lipid mediators in subtypes of asthma is not well understood.

OBJECTIVE

To investigate the interactions between airway inflammation and clinical phenotypes of asthma, we integrated induced sputum supernatant (ISS) eicosanoids and quantitative assessment of infiltrating cells into new subtypes with the means of latent class analysis (LCA).

METHODS

One hundred and thirty-nine asthmatics with and without aspirin hypersensitivity underwent sputum induction. High-performance liquid chromatography or gas chromatography coupled with mass spectrometry was used to profile eicosanoids. Nineteen variables covering clinical characteristics, IS inflammatory cells and eicosanoids were considered in the LCA.

RESULTS

Four phenotypic asthma classes were distinguished. Class 1 with mild-to-moderate asthma, chronic rhinosinusitis (CRS), high PGA2 in ISS and almost equal distribution of inflammation cell patterns. Class 3 subjects also had mild-to-moderate asthma but without upper airway symptoms. Induced sputum was often paucigranulocytic with low levels of lipid mediators. Classes 2 and 4 represented severe asthma with CRS and impaired lung function despite high doses of steroids. High blood and sputum eosinophilia was in line with high cysteinyl leukotrienes and PGD2 in ISS only in class 2. Class 4 subjects tended to have increased sputum neutrophilia and PGE2 in ISS. Aspirin hypersensitivity was most frequent among class 2 subjects.

CONCLUSIONS & CLINICAL RELEVANCE

The LCA revealed four distinct asthma classes differing in eicosanoid pathways.

Clinical and inflammatory features of asthma with dissociation between fractional exhaled nitric oxide and eosinophils in induced sputum

BACKGROUND

Measurement of the fractional exhaled nitric oxide (FeNO) and eosinophils in induced sputum are noninvasive markers for assessing airway inflammation in asthma. The clinical usefulness of the correlation between raised FeNO and sputum eosinophilia is controversial. We aimed to examine dissociation between FeNO and sputum eosinophils in a clinical series of asthma patients and to determine whether dissociation between these noninvasive markers was associated with clinical and inflammatory differences in these patients.

METHODS AND FINDINGS

A total of 110 patients with asthma were included in a cross-sectional study. All of them were on maintenance treatment for asthma. All patients underwent the following on the same day: FeNO, induced sputum, spirometry, serum total IgE levels and skin prick test. The level of asthma control was determined by the Asthma control Test Questionnaire. In 46 (41.8%) patients, a discrepancy between FeNO and sputum eosinophil count was observed, of those, 34 (73.9%) had a FeNO <50 ppb and high eosinophil count, and were characterized by having a predominance of nonallergic asthma with bronchial eosinophilic inflammatory phenotype. Also, 12 (26.1%) patients had FeNO ≥50 ppb and sputum eosinophilia within the normal reference values, and were characterized by having a predominance of atopy with a paucigranulocytic inflammatory phenotype.

CONCLUSIONS

A high percentage of patients with dissociation between results of FeNO and sputum eosinophils was observed. These patients showed differential clinical and inflammatory features.

Different patterns of exhaled nitric oxide response to β2-agonists in asthmatic patients according to the site of bronchodilation

BACKGROUND

In asthmatic patients undergoing airway challenge, fraction of exhaled nitric oxide (FENO) levels decrease after bronchoconstriction. In contrast, model simulations have predicted both decreased and increased FENO levels after bronchodilation, depending on the site of airway obstruction relief.

OBJECTIVE

We sought to investigate whether β2-agonists might induce divergent effects on FENO values in asthmatic patients as a result of airway obstruction relief occurring at different lung depths.

METHODS

FENO, FEV1, and the slope of phase III of the single-breath washout test (S) of He (S(He)) and sulfur hexafluoride (S(SF6)) were measured in 68 asthmatic patients before and after salbutamol inhalation. S(He) and S(SF6) decreases reflected preacinar and intra-acinar obstruction relief, respectively. Changes (Δ) were expressed as a percentage from the baseline.

RESULTS

No FENO change (|ΔFENO| ≤ 10%) was found in 16 patients (mean [SD]: 2.5% [5.2%]; ie, FENO= group); a ΔFENO value of greater than 10% was found in 23 patients (31.7% [20.3%]; ie, the FENO+ group); and a ΔFENO value of less than -10% was found in 29 patients (-31.5% [17.3%]; ie, the FENO- group). All groups had similar ΔFEV1 values. In the FENO= group neither S(He) nor S(SF6) changed, in the FENO+ group only S(He) decreased significantly (-21.8% [SD 28.5%], P = .03), and in the FENO- group both S(He) (-29.8% [24.0%], P < .001) and S(SF6) (-27.2% [23.3%], P < .001) decreased.

DISCUSSION

Three FENO behaviors were observed in response to β2-agonists: a decrease likely caused by relief of an intra-acinar airway obstruction that we propose reflects amplification of nitric oxide back-diffusion, an increase likely associated with a predominant dilation up to the preacinar airways, and FENO stability when obstruction relief involved predominantly the central airways. In combination, these results suggest a new role for FENO in identifying the site of airway obstruction in asthmatic patients.

iNOS affects matrix production in distal lung fibroblasts from patients with mild asthma

INTRODUCTION

A high level of exhaled nitric oxide (NO) is a marker for inflammation in the airways of asthmatic subjects. However, little is known about how NO and inducible nitric oxides synthase (iNOS) activity may affect remodelling in the distal lung. We hypothesized that there is a link between iNOS and ongoing remodelling processes in the distal lung of mild asthmatics.

METHODS

Patients with mild asthma (n = 6) and healthy control subjects (n = 8) were included. Exhaled NO was measured at different flow rates and alveolar NO concentrations were calculated. For studies of remodelling processes in the distal lung, primary fibroblasts were grown from transbronchial biopsies and stimulated with unselective and selective NOS inhibitors or a NO donor. The mRNA expression of iNOS and synthesis of NO (indirectly as nitrite/nitrate) were measured and distal lung fibroblast synthesis of the extracellular matrix proteoglycans were analysed.

RESULTS

The distal lung fibroblasts expressed iNOS, and there was a tendency of higher expression in fibroblasts from patients with asthma. The selective iNOS inhibitor 1400 W inhibited iNOS expression and NO synthesis in fibroblasts from patients with asthma (p = 0.031). Treatment with 1400 W significantly increased synthesis of the proteoglycan versican (p = 0.018) in distal fibroblasts from patients with asthma whereas there were no effects in fibroblasts from control subjects.

CONCLUSIONS

Our data suggest that there is a link between iNOS and remodelling in the distal lung of subjects with mild asthma and that iNOS could have a modulatory role in pathological airway remodelling.

Application of nitric oxide measurements in clinical conditions beyond asthma

Fractional exhaled nitric oxide (FeNO) is a convenient, non-invasive method for the assessment of active, mainly Th2-driven, airway inflammation, which is sensitive to treatment with standard anti-inflammatory therapy. Consequently, FeNO serves as a valued tool to aid diagnosis and monitoring in several asthma phenotypes. More recently, FeNO has been evaluated in several other respiratory, infectious, and/or immunological conditions. In this short review, we provide an overview of several clinical studies and discuss the status of potential applications of NO measurements in clinical conditions beyond asthma.

Small airway disease in asthma: pathophysiological and diagnostic considerations

PURPOSE OF REVIEW

The aim of the current review is to summarize the evidence of small airway abnormalities in asthma, the proposed diagnostic tools for small airway abnormalities and the clinical implications of small airway abnormalities in asthma.

RECENT FINDINGS

Pathological abnormalities in the peripheral membranous bronchioles less than 2 mm in diameter (i.e. small airways) can be very frequently detected in asthma patients across severity: from mild to the more severe clinical manifestations of the disease. Interestingly, not only are small airway abnormalities present in asthma, but there is evidence that the magnitude of small airway abnormalities correlates with the severity of the disease. So far no unanimously accepted method and/or algorithm is available for small airway abnormality detection; however, some functional techniques and inflammatory markers have been used as surrogates of small airway dysfunction.

SUMMARY

Clinicians, and not only researchers, must consider small airways when approaching asthma patients, particularly when dealing with patients with a 'difficult-to-treat phenotype'. The identification of subgroups of asthma patients with prominent small airway disease is not merely speculative, and carries pathophysiological and therapeutic implications.