Sputum analysis, bronchial hyperresponsiveness, and airway function in asthma: results of a factor analysis

Assessing the prognostic value of respiratory oscillometry in patients with difficult-to-treat asthma

Respiratory oscillometry is widely explored in asthma management; however, there is currently no consensus on its routine work-up in patients with difficult-to-treat asthma. We conducted a retrospective, cross-sectional study involving patients with difficult-to-treat asthma at Asia University Hospital between January 2017 and October 2020. We aimed to correlate clinical significance of respiratory oscillometry and asthma treatment outcomes including symptoms control and exacerbation in patients with difficult-to-treat asthma. Among the 69 patients enrolled in the study, a total of 26.1% of the patients experienced at least one severe or two moderate exacerbations. Patients with ACT < 20 presented a higher prevalence of higher frequency-dependent resistance (FDR; the difference in resistance at 5 Hz and 20 Hz) and frequency of resonance (Fres) than those with ACT ≥ 20. In the multivariable analysis, comorbidities, COPD or allergic rhinitis, and FDR were independent factors in increasing the odds ratio in poorly controlled asthma. (FDR ≥ 0.10 vs. < 0.10, adjusted ORR = 5.05, P = 0.037) There was a higher proportion of frequent exacerbations in patients with higher FDR (FDR ≥ 0.10 vs. < 0.10 = 30.0%:20.7%), but IOS parameters failed to predict frequent exacerbations on further analysis. FDR may be a potential clinical parameter for predicting symptom control in patients with difficult-to-treat asthma.

Sputum Eosinophilia and Magnetic Resonance Imaging Ventilation Heterogeneity in Severe Asthma

RATIONALE

Inflammation and smooth muscle dysfunction are integral components of severe asthma that contribute to luminal obstruction causing airflow limitation, ventilation heterogeneity, and symptoms. This is important for guiding treatment decisions directed at the inflammatory (e.g., anti-T-helper cell type 2 monoclonal antibodies) and noninflammatory, smooth muscle-mediated (e.g., bronchial thermoplasty) components of severe asthma.

OBJECTIVES

To investigate the contribution of eosinophilic bronchitis and smooth muscle dysfunction to magnetic resonance imaging (MRI) ventilation heterogeneity in patients with severe asthma.

METHODS

We measured the inhaled hyperpolarized gas MRI response to salbutamol as a marker of smooth muscle dysfunction, and sputum eosinophils as a marker of airway inflammation, and their contributions to ventilation heterogeneity (quantified as the ventilation defect percent [VDP]) in 27 patients with severe asthma. Spirometry and forced oscillation airway resistance measurements were also acquired pre- and postsalbutamol. Patients were dichotomized on the basis of sputum eosinophilia, and pre- and postsalbutamol VDP and physiological measurements were evaluated.

MEASUREMENTS AND MAIN RESULTS

MRI VDP improved with salbutamol inhalation in patients in whom sputum eosinophilia was uncontrolled (≥3%, n = 16) (P = 0.002) and in those in whom it was controlled (<3%, n = 11) (P = 0.02), independent of improvements in FEV₁, indicating smooth muscle response. In those patients in whom sputum eosinophilia was uncontrolled, greater VDP persisted postsalbutamol (P = 0.004). Postsalbutamol VDP correlated with sputum eosinophils (r = 0.63; P = 0.005).

CONCLUSIONS

In patients with severe asthma, MRI regionally identifies the inflammatory and noninflammatory components of airway disease. Ventilation heterogeneity persists postsalbutamol in patients with uncontrolled eosinophilic bronchitis, which may be the functional consequence of airway inflammation.

Accuracy of objective tests for diagnosing adult asthma in symptomatic patients: A systematic literature review and hierarchical Bayesian latent-class meta-analysis

BACKGROUND

We obtain summary estimates of the accuracy of additional objective tests for the diagnosis of adult asthma using systematic review and meta-analysis of diagnostic test accuracy studies.

METHODS

Medline, Embase, and other relevant electronic databases were searched for papers published between January 1989 and December 2016. Studies were included if they evaluated the diagnostic accuracy of objective tests, including airway reversibility (AR), airway hyperresponsiveness (AHR), and fractionated exhaled nitric oxide (FeNO) for the diagnosis of adult asthma in patients with symptoms suggestive of asthma. If papers were assessed appropriate using the adapted QUADAS-2 tool, meta-analysis was conducted using the hierarchical bivariate model. This hierarchical model accounts for both within and between study variability.

RESULTS

Sixteen studies reported the performance of the evaluated objective tests at presentation. For diagnosis of adult asthma, overall sensitivity and specificity for AR were 0.39 (95% confidence interval [CI] 0.18 to 0.66) and 0.95 (95% CI 0.86 to 1.00); for AHR, 0.86 (95% CI 0.61 to 1.00) and 0.95 (95% CI 0.77 to 1.00); for FeNO, 0.65 (95% CI 0.53 to 0.77) and 0.83 (95% CI 0.75 to 0.90). Comprehensive comparison of three diagnostic tools for adult asthma using the back-calculated likelihood rate (LR) showed that AR and AHR corresponded to a higher LR+, and AHR gave a lower LR-.

CONCLUSIONS

In the current situation of no gold standard for diagnosis of adult asthma, AR and AHR are appropriate for ruling-in the true diagnosis, and AHR is superior for ruling-out a diagnosis. Since each objective test had a specific characteristic, it should be chosen depending on the situation, such as the capacity of the institution and the conditions of patients.

Novel methods for device and adherence monitoring in asthma

PURPOSE OF REVIEW

The article aims to provide an updated and evidence-based review of the innovative electronic health interventions to monitor and improve inhaler technique and adherence to recommended therapy in asthma.

RECENT FINDINGS

Out of the 290 articles identified by the search strategy, 23 manuscripts fulfilled the review inclusion criteria. Included studies mainly addressed m-health, electronic reminders, telemedicine, and inhaler tracker interventions. Investigations were performed both in adults and children. Remarkably, the majority of studies were performed in the most recent years, showing a progressively increasing interest for this field. Existing findings appear to be of moderate-high quality. A significant number of papers, however, were published in scientific journals with a low impact factor (<2). Furthermore, extremely high heterogeneity was found in the considered study endpoints. Collected evidence supports a relevant role for e-health in monitoring and improving inhaler use and treatment adherence in asthma. The patients' acceptance and satisfaction towards assessed interventions were also found to be positive.

SUMMARY

E-health represents a highly valuable tool for achieving optimal and personalized asthma management. Unanimously agreed and adopted standards for conducting trials and reporting results on e-health in asthma are however needed to fully understand its real added value.

Clinical outcomes of levalbuterol versus racemic albuterol in pediatric patients with asthma: Propensity score matching approach in a medicaid population

OBJECTIVE

Racemic albuterol and levalbuterol are used to treat acute episodes of asthma. The main objective of this study was to compare levalbuterol therapy to albuterol therapy on incidence rates of subsequent emergency department (ED) visits and hospitalizations.

METHOD

We conducted a retrospective cohort study of asthmatic children who had pharmacy refills for levalbuterol/albuterol in the South Carolina Medicaid database in 2002-2011. Children receiving levalbuterol were matched to those receiving albuterol using propensity score matching technique. For ED visits and separately for hospitalizations, multivariable negative binomial regression was used to estimate the two group-specific incidence rates and the incidence rate ratio (IRR).

RESULTS

A total of 8,172 asthmatic patients aged 2-18 years were identified in the South Carolina Medicaid database. During the 12-month follow-up period, the levalbuterol group had fewer asthma-related ED visits and hospitalizations: 939 (11.49%) children had asthma-related ED visits (levalbuterol: 8.76%; albuterol: 14.21%), and 89 (1.09%) children had asthma-related hospitalizations (levalbuterol: 1.07%; albuterol: 1.12%). Comparing the levalbuterol group to the albuterol group, the adjusted IRR estimate was 0.57 (95% confidence interval [CI], 0.49-0.65) for of asthma-related ED visits, and 0.93 (95%CI, 0.99-1.63) for hospitalizations. Children filling levalbuterol also had a lower IRR of all-cause ED visit (0.88; 95%CI, 0.82-0.95), but similar IRR of all-cause hospitalizations (1.08; 95%CI, 0.82-1.42).

CONCLUSION

This observational study of children aged 2-18 demonstrated levalbuterol prescription fills were associated with reduced ED visits, but not hospitalizations. Additional research may be necessary to assess this association. Pediatr Pulmonol. 2017;52:516-523. © 2016 Wiley Periodicals, Inc.

Clinical Characteristics of Exacerbation-Prone Adult Asthmatics Identified by Cluster Analysis

PURPOSE

Asthma is a heterogeneous disease characterized by various types of airway inflammation and obstruction. Therefore, it is classified into several subphenotypes, such as early-onset atopic, obese non-eosinophilic, benign, and eosinophilic asthma, using cluster analysis. A number of asthmatics frequently experience exacerbation over a long-term follow-up period, but the exacerbation-prone subphenotype has rarely been evaluated by cluster analysis. This prompted us to identify clusters reflecting asthma exacerbation.

METHODS

A uniform cluster analysis method was applied to 259 adult asthmatics who were regularly followed-up for over 1 year using 12 variables, selected on the basis of their contribution to asthma phenotypes. After clustering, clinical profiles and exacerbation rates during follow-up were compared among the clusters.

RESULTS

Four subphenotypes were identified: cluster 1 was comprised of patients with early-onset atopic asthma with preserved lung function, cluster 2 late-onset non-atopic asthma with impaired lung function, cluster 3 early-onset atopic asthma with severely impaired lung function, and cluster 4 late-onset non-atopic asthma with well-preserved lung function. The patients in clusters 2 and 3 were identified as exacerbation-prone asthmatics, showing a higher risk of asthma exacerbation.

CONCLUSIONS

Two different phenotypes of exacerbation-prone asthma were identified among Korean asthmatics using cluster analysis; both were characterized by impaired lung function, but the age at asthma onset and atopic status were different between the two.

Concordance between bronchial hyperresponsiveness, fractional exhaled nitric oxide, and asthma control in children

BACKGROUND

Previous studies on association between level of asthma control, markers of airway inflammation and the degree of bronchial hyperresponsiveness (BHR) have yielded conflicting results. Our aim was to determine the presence and severity of BHR and the concordance between BHR, asthma control, and fractional exhaled nitric oxide (FeNO) in children with asthma on therapy.

METHODS

In this cross-sectional observational study, children (aged 6-18 years) with asthma on British Thoracic Society (BTS) treatment steps 2 or 3, underwent comprehensive assessment of their asthma control (clinical assessment, spirometry, asthma control test [ACT], Pediatric Asthma Quality of Life Questionnaire [PAQLQ]), measurement of FeNO and BHR (using mannitol dry powder bronchial challenge test [MCT], Aridol™, Pharmaxis, Australia).

RESULTS

Fifty-seven children (63% male) were studied. Twenty-seven children were on BTS treatment step 2 and 30 were on step 3. Overall, 25 out of 57 (43.8%) children had positive MCT. Of note, 9 out of 27 (33.3%) children with clinically controlled asthma had positive MCT. Analyses of pair-wise agreement between MCT (positive or negative), FeNO (>25 or ≤25 ppb) and clinical assessment of asthma control (controlled or partially controlled/uncontrolled) showed poor agreement between these measures.

CONCLUSIONS

A substantial proportion of children with asthma have persistent BHR despite good clinical control. The concordance between clinical assessment of asthma control, BHR and FeNO was observed to be poor. Our findings raise concerns in the context of emerging evidence for the role of bronchoconstriction in inducing epithelial stress that may drive airway remodeling in asthma. Pediatr Pulmonol. 2016;51:1004-1009. © 2016 Wiley Periodicals, Inc.

Identification of Asthma Subtypes Using Clustering Methodologies

Asthma is a heterogeneous disease comprising a number of subtypes which may be caused by different pathophysiologic mechanisms (sometimes referred to as endotypes) but may share similar observed characteristics (phenotypes). The use of unsupervised clustering in adult and paediatric populations has identified subtypes of asthma based on observable characteristics such as symptoms, lung function, atopy, eosinophilia, obesity, and age of onset. Here we describe different clustering methods and demonstrate their contributions to our understanding of the spectrum of asthma syndrome. Precise identification of asthma subtypes and their pathophysiological mechanisms may lead to stratification of patients, thus enabling more precise therapeutic and prevention approaches.

Does airway hyperresponsiveness monitoring lead to improved asthma control?

The current guidelines recommend an approach to asthma management based on asthma control, rather than asthma severity. Although several specific questionnaires have been developed and control criteria have been established based on clinical guidelines, the evaluation of asthma control is still not optimal. In general, these indicators provide adequate assessment of current control, but they are more limited when estimating future risk. There is much evidence demonstrating the persistence of airway inflammation and airway hyperresponsiveness (AHR) in patients with total control. Therefore, the objective of this review was to analyse the possible role of AHR monitoring as an instrument for assessing asthma control. We will evaluate its capacity as an indicator for future risk, both for estimating the possibility of clinical deterioration and loss of lung function or exacerbations. Furthermore, its relationship with inhaled corticosteroid treatment will be analysed, while emphasizing its capacity for predicting response and adjusting dosage, as well as information about the capability of AHR for monitoring treatment. Last of all, we will discuss the main limitations and emerging opportunities of AHR as an assessment instrument for asthma control.

[Severe asthma: Characteristics of patients in clinical practice]

AIM

To provide clinical characteristics of severe asthma (SA) patients encountered in clinical practice.

SUBJECTS AND METHODS

A cross-sectional cohort study was performed to cover 119 outpatients aged 22-82 years. SA was diagnosed according to the ERS/ATS criteria (2014). Spirometry and bronchodilator reversibility testing were carried out; fractional exhaled nitric oxide (FeNO) was measured; inhalant allergen hypersensitivity (skin prick and blood specific IgE testing) and peripheral blood eosinophil counts were estimated. Asthma control and asthma-related quality of life were assessed.

RESULTS

77% of the patients were found to have allergic asthma; in this case, house dust mites were leading allergens in the spectrum of sensitization. 82% of the patients were observed to have uncontrolled asthma and 76% had incompletely reversible bronchial obstruction. The airway eosinophilic inflammation markers (FeNO more than 25 ppb and eosinophil counts of more than 150 cells/µ) were elevated in 63% of the patients. Good compliance was noted in 61% of the patients. There were 27% of active smokers who had lower lung function and FeNO levels. The smokers showed a low compliance with inhaled glucocorticosteroid treatment. SA was concurrent with chronic obstructive pulmonary disease in 37% of the cases.

CONCLUSION

SA is a heterogeneous disease. Traditional treatment is not always effective, as many patients, despite their treatment, have uncontrolled SA and continuously increased markers of airways eosinophilic inflammation. Monoclonal antibody therapy may promote success in treating this cohort of patients.

Can exhaled nitric oxide be a surrogate marker of bronchial hyperresponsiveness to adenosine 5'-monophosphate in steroid-naive asthmatic children?

BACKGROUND

The interrelation between airway inflammation, bronchial hyperresponsiveness (BHR) and atopy remains controversial.

OBJECTIVE

The aim of this study was to document whether exhaled nitric oxide (eNO) may be used as a surrogate marker that predicts BHR to adenosine 5'-monophosphate (AMP) in steroid-naive school children with asthma.

METHODS

This study was a retrospective analysis of steroid-naive school age children with atopic and non-atopic asthma. All patients whose eNO levels had been measured and who had been challenged with both methacholine (MCH) and AMP were included. Receiver operation characteristic analysis was performed, in both the atopic and the non-atopic groups, to evaluate the ability of eNO to detect the BHR to AMP.

RESULTS

One hundred and sixteen patients, sixty-nine (59.5%) of whom had been atopic, were included in the analysis. In the atopic group, eNO values were significantly higher in patients with BHR to AMP compared to those without BHR to AMP (51.9 ± 16.9 p.p.b. vs. 33.7 ± 16.4 p.p.b.; P < 0.001), whereas in the non-atopic group, the differences were not statistically significant (29.7 ± 16.9 p.p.b. vs. 22.6 ± 8.1 p.p.b.; P = 0.152). In the atopic group, eNO levels (R(2) : 0.401; β: 0.092; 95% CI: 1.19-14.42; OR: 7.12; P = 0.008) were found to be the only independent factor for BHR to AMP, whereas none of the parameters predicted BHR to AMP in the non-atopic group. The best cut-off value of eNO that significantly predicts BHR to AMP was 33.3 p.p.b. in the atopic group (P < 0.001), whereas a significant cut-off value for eNO that predicts BHR to AMP was not determined in the non-atopic group (P = 0.142). An eNO ≤ 17.4 p.p.b. has 100% negative predictive values and 100% sensitivity and 60.47% PPV for prediction of BHR to AMP in the atopic group.

CONCLUSIONS

Exhaled NO may be used to predict BHR to AMP in atopic but not in non-atopic steroid-naïve asthmatic children.

Disease models of chronic inflammatory airway disease: applications and requirements for clinical trials

PURPOSE OF REVIEW

This review will discuss methodologies and applicability of key inflammatory models of respiratory disease in proof of concept or proof of efficacy clinical studies. In close relationship with these models, induced sputum and inflammatory cell counts will be addressed for phenotype-directed drug development. Additionally, important regulatory aspects regarding noninvestigational medicinal products used in bronchial challenges or clinical inflammatory models of respiratory disease will be highlighted.

RECENT FINDINGS

The recognition of an ever increasing number of phenotypes and endotypes within conditions such as asthma and chronic obstructive pulmonary disease urges phenotyping of study populations already in early clinical phases of drug development. Apart from the choice of a relevant disease model, recent studies show that especially targeted therapies need to be tested in well defined disease subsets for adequate efficacy assessment. Noninvasive biomarkers, especially sputum inflammatory cell counts, aid phenotyping and are useful outcome measures for novel, targeted therapies.

SUMMARY

Disease phenotyping becomes increasingly important for efficient and cost-effective drug development and subsequent disease management. Inflammatory models of respiratory disease combined with sputum biomarkers are important tools in this approach.

Early postnatal, but not late, exposure to chemical ambient pollutant 1,2-naphthoquinone increases susceptibility to pulmonary allergic inflammation at adulthood

High diesel exhaust particle levels are associated with increased health effects; however, knowledge on the impact of its chemical contaminant 1,2-naphthoquinone (1,2-NQ) is limited. We investigated whether postnatal and adult exposures to 1,2-NQ influence allergic reaction and the roles of innate and adaptive immunity. Male neonate (6 days) and adult (56 days) C57Bl/6 mice were exposed to 1,2-NQ (100 nM; 15 min) for 3 days, and on day 59, they were sensitized and later challenged with ovalbumin (OVA). Airway hyper-responsiveness (AHR) and production of cytokines, immunoglobulin E (IgE) and leukotriene B4 (LTB4) were measured in the airways. Postnatal exposure to 1,2-NQ activated dendritic cells in splenocytes by increasing expressing cell surface molecules (e.g., CD11c). Co-exposure to OVA effectively polarized T helper (Th) type 2 (Th2) by secreting Th2-mediated cytokines. Re-stimulation with unspecific stimuli (PMA and ionomycin) generated a mixed Th1 (CD4(+)/IFN-γ(+)) and Th17 (CD4(+)/IL-17(+)) phenotype in comparison with the vehicle-matched group. Postnatal exposure to 1,2-NQ did not induce eosinophilia in the airways at adulthood, although it evoked neutrophilia and exacerbated OVA-induced eosinophilia, Th2 cytokines, IgE and LTB4 production without affecting AHR and mast cell degranulation. At adulthood, 1,2-NQ exposure evoked neutrophilia and increased Th1/Th2 cytokine levels, but failed to affect OVA-induced eosinophilia. In conclusion, postnatal exposure to 1,2-NQ increases the susceptibility to antigen-induced asthma. The mechanism appears to be dependent on increased expression of co-stimulatory molecules, which leads to cell presentation amplification, Th2 polarization and enhanced LTB4, humoral response and Th1/Th2 cytokines. These findings may be useful for future investigations on treatments focused on pulmonary illnesses observed in children living in heavy polluted areas.

Which biomarkers are effective for identifying Th2-driven inflammation in asthma?

Recognition of asthma as a heterogeneous disease revealed different potential molecular targets and urged the development of targeted, customized treatment modalities. Evidence was provided for different inflammatory subsets of asthma and more recently, further refined to T helper (Th)2-high and Th2-low subphenotypes with different responsiveness to standard and targeted pharmacotherapy. Given these differences in immunology and pathophysiology, proof of concept studies of novel treatment modalities for asthma should be performed in adequate, well-defined phenotypes. In this review, we describe both existing and novel biomarkers of Th2-inflammation in asthma that can be applied to classify asthma subphenotypes in clinical studies and for treatment monitoring.

Using fractional exhaled nitric oxide (FeNO) to diagnose steroid-responsive disease and guide asthma management in routine care

BACKGROUND

Fractional exhaled nitric oxide (FeNO) is a surrogate marker of eosinophilic airway inflammation and good predictor of corticosteroid response.

AIM

To evaluate how FeNO is being used to guide primary care asthma management in the United Kingdom (UK) with a view to devising practical algorithms for the use of FeNO in the diagnosis of steroid-responsive disease and to guide on-going asthma management.

METHODS

Eligible patients (n = 678) were those in the Optimum Patient Care Research Database (OPCRD) aged 4-80 years who, at an index date, had their first FeNO assessment via NIOX MINO® or Flex®. Eligible practices were those using FeNO measurement in at least ten patients during the study period. Patients were characterized over a one-year baseline period immediately before the index date. Outcomes were evaluated in the year immediately following index date for two patient cohorts: (i) those in whom FeNO measurement was being used to identify steroid-responsive disease and (ii) those in whom FeNO monitoring was being used to guide on-going asthma management. Outcomes for cohort (i) were incidence of new ICS initiation at, or within the one-month following, their first FeNO measurement, and ICS dose during the outcome year. Outcomes for cohort (ii) were adherence, change in adherence (from baseline) and ICS dose.

OUTCOMES

In cohort (i) (n = 304) the higher the FeNO category, the higher the percentage of patients that initiated ICS at, or in the one month immediately following, their first FeNO measurement: 82%, 46% and 26% of patients with high, intermediate and low FeNO, respectively. In cohort (ii) (n = 374) high FeNO levels were associated with poorer baseline adherence (p = 0.005) but greater improvement in adherence in the outcome year (p = 0.017). Across both cohorts, patients with high FeNO levels were associated with significantly higher ICS dosing (p < 0.001).

CONCLUSIONS

In the UK, FeNO is being used in primary practice to guide ICS initiation and dosing decisions and to identify poor ICS adherence. Simple algorithms to guide clinicians in the practical use of FeNO could improved diagnostic accuracy and better tailored asthma regimens.

Comparison of direct and indirect bronchoprovocation testing using ventilator-acquired pulmonary mechanics in healthy cats and cats with experimental allergic asthma

Airway hyperresponsiveness (AHR) is a key feature of asthma and can be measured using bronchoprovocation. Direct (methacholine, MCh) or indirect (adenosine-5-monophosphate, AMP; or mannitol) bronchoprovocants are used in human patients, the latter inducing AHR only with pre-existing airway inflammation. The present study compared the responses to direct (MCh) and indirect (mannitol, AMP) bronchoprovocation in healthy and asthmatic cats (n=6/group). The order of bronchoprovocant was randomized using a published table of random numbers and there was a 1-month washout before crossover to the next treatment. Pulmonary mechanics were measured in anesthetized and mechanically ventilated cats using a critical care ventilator. Saline at baseline and increasing doses of each bronchoprovocant were aerosolized for 30 s, followed by 4 min of data collection between doses. The endpoint for each bronchoprovocant was reached when airway resistance exceeded 200% of baseline values (EC200Raw). There was a significant difference (P<0.001) in the airway response of asthmatic vs. healthy cats over the range of MCh concentrations, despite there being no significant difference in the EC200Raw between the groups. Response to MCh was significantly greater (P<0.05) in asthmatic than in healthy cats at MCh concentrations as low as 0.0625 mg/mL. For AMP, a small subset of asthmatics (n=2/6) responded at low concentrations; four asthmatic cats and all healthy cats failed to respond even to the highest concentrations of AMP. One asthmatic cat but no healthy cats responded to mannitol. In conclusion, MCh discriminated asthmatic from healthy cats but neither AMP nor mannitol was an effective bronchoprovocant in this model.

Immunological parameters and gene polymorphisms (C-590T IL4, C-597A IL10) in severe bronchial asthma in children from the Krasnoyarsk region, West Siberia

Background

Bronchial asthma is a common disease caused by interplay between multiple determinants, including genetic and immune variations.

Objective

To investigate the main indices of humoral and cellular branches of immunity, features of cytokine regulation and cytokine genes in children with atopic bronchial asthma (BA) with different levels of disease control.

Design

Fifty children with controlled BA (CBA) and 50 with uncontrolled BA (UBA) were analyzed. Mean age in the sample was 13.36±2.24 years. A control group of healthy children (n=50) was also studied. All individuals were Russians (Eastern Slavs) from the Krasnoyarsk Territory, West Siberia. Diagnoses, severity and level of disease control were defined according to the Global Initiative for Asthma (GINA) recommendations. The lymphocytes were counted in blood using fluorescent microscopy. Humoral branch indices and cytokine levels (IL-2, IL-4, IL-10 and TNF-α) in blood serum were measured by ELISA. Genotyping of single-nucleotide polymorphism (SNP) in −590 position of the IL4 and −597 position of the IL10 gene was performed by restriction fragment length analysis.

Results

No statistically significant differences in total IgE and cytokines blood levels were found in CBA and UBA. However, significant differences between the groups were found for CD³⁺, CD⁴⁺ and CD⁸⁺ cell counts. The T-590 allele of the IL4 gene, which is responsible for an increased serum level of IL-4, showed a tendency to an association with UBA. A decreased level of IL-10 enhances control over BA, which proves its association with the allelic variant A-597 IL10.

Conclusion

Our data show that children with UBA have higher counts of CD³⁺ cells and an increase of sub-population of CD⁴⁺-cells as well as higher levels of IgE, IL-4 and TNF-α in blood serum as compared to CBA. Polymorphisms of the IL4 and IL10 genes are associated with allergic inflammation in UBA.

Exhaled nitric oxide as screening tool in subjects with suspected asthma without reversibility

BACKGROUND

As fractional exhaled nitric oxide (FeNO) has been evaluated only in certain settings for asthma diagnosis, we investigated whether FeNO values could predict positive methacholine challenge testing (expressed as PD20) in subjects with suspected asthma but without spirometric reversibility.

METHODS

Subjects with asthma-like symptoms and negative bronchodilation test were initially evaluated to undergo FeNO measurement and methacholine bronchial challenge. Diagnostic performance of FeNO to predict PD20 to methacholine <800 μg was examined by constructing receiver-operating characteristic curves.

RESULTS

A total of 112 subjects met the inclusion criteria. In all subjects, FeNO >32 ppb was associated with a sensitivity of 0.47 and a specificity of 0.85 for the identification of the PD20 <800 μg (AUC = 0.691, 95% CI = 0.6-0.775, p = 0.00002). In smokers, FeNO >11 ppb was associated with a sensitivity of 0.85 and a specificity of 0.5 for the identification of PD20 <800 μg (AUC = 0.625, 95% CI = 0.45-0.772, p = 0.18), while in atopics a FeNO level >26 ppb was associated with a sensitivity of 0.55 and a specificity of 0.85 (AUC = 0.677, 95% CI = 0.53-0.8, p = 0.02).

CONCLUSIONS

In subjects with symptoms compatible with asthma but without spirometric reversibility, specific cutoff levels for FeNO levels significantly predict the positive methacholine challenge, with significant confounding factors being atopy and current smoking.

Assessment of murine lung mechanics outcome measures: alignment with those made in asthmatics

Although asthma is characterized as an inflammatory disease, recent reports highlight the importance of pulmonary physiology outcome measures to the clinical assessment of asthma control and risk of asthma exacerbation. Murine models of allergic inflammatory airway disease have been widely used to gain mechanistic insight into the pathogenesis of asthma; however, several aspects of murine models could benefit from improvement. This review focuses on aligning lung mechanics measures made in mice with those made in humans, with an eye toward improving the translational utility of these measures. A brief description of techniques available to measure murine lung mechanics is provided along with a methodological consideration of their utilization. How murine lung mechanics outcome measures relate to pulmonary physiology measures conducted in humans is discussed and we recommend that, like human studies, outcome measures be standardized for murine models of asthma.

Mast cell engraftment of the peripheral lung enhances airway hyperresponsiveness in a mouse asthma model

Allergic asthma is a chronic inflammatory disease, characterized by airway hyperresponsiveness (AHR), inflammation, and tissue remodeling, in which mast cells play a central role. In the present study, we analyzed how mast cell numbers and localization influence the AHR in a chronic murine model of asthma. C57BL/6 (wild-type) and mast cell-deficient B6.Cg-Kit(W-sh) mice without (Wsh) and with (Wsh+MC) mast cell engraftment were sensitized to and subsequently challenged with ovalbumin for a 91-day period. In wild-type mice, pulmonary mast cells were localized in the submucosa of the central airways, whereas the more abundant mast cells in Wsh+MC mice were found mainly in the alveolar parenchyma. In Wsh+MC, ovalbumin challenge induced a relocation of mast cells from the perivascular space and central airways to the parenchyma. Allergen challenge caused a similar AHR in wild-type and Wsh mice in the resistance of the airways and the pulmonary tissue. In Wsh+MC mice the AHR was more pronounced. The elevated functional responses were partly related to the numbers and localization of connective tissue-type mast cells in the peripheral pulmonary compartments. A mast cell-dependent increase in IgE and IL-33 together with impairment of the IL-23/IL-17 axis was evoked in Wsh and Wsh+MC mice by allergen challenge. This study shows that within the same chronic murine asthma model the development of AHR can be both dependent and independent of mast cells. Moreover, the spatial distribution and number of pulmonary mast cells determine severity and localization of the AHR.

Subjective cold hyper-responsiveness grade reflects age- and duration-related increase of nonspecific nasal hyperreactivity

OBJECTIVE

We evaluated the effect of patients' age and duration of allergic rhinitis on nonspecific nasal hyper-reactivity (NHR) using cold dry air (CDA) provocation.

METHODS

In 156 patients of various ages with allergic rhinitis and different symptom duration, we evaluated the change of symptoms, the subjective cold hyper-responsiveness (SCH) grade, the change of acoustic parameters such as total nasal volume (TNV) and minimal cross-sectional area (MCA), and the amount of rhinorrhea before and after CDA provocation.

RESULTS

Patients in different age or duration groups did not show significant differences in the change of each nasal symptom. SCH grade 2 or 3 was more frequently observed in patients older than 30 years (p=0.018). There was a significant correlation between the age of the patients and the SCH grade (R=0.184, p=0.022). Patients with >10 years of duration reported higher SCH grade (p=0.022). There was a significant correlation between the duration of disease and SCH grade (R=0.284, p<0.001). However, there were no significant differences in the change of TNV and MCA, and the amount of rhinorrhea after CDA provocation between different age and duration groups.

CONCLUSION

SCH grade reflects the age- and duration-related increase of NHR. Further studies to elucidate the pathophysiologic mechanisms are needed in the future.

Anti-Interleukin-5 Monoclonal Antibodies

Descriptive studies have shown an association between eosinophils, interleukin (IL)-5 and pathophysiological processes in patients with atopic asthma. These observations have led to an interest in the eosinophil as the pathogenic cell responsible for many of the clinical features of asthma including symptoms of wheeze, shortness of breath and cough, along with the physiological events such as airway hyperresponsiveness (AHR) and changes in lung function. IL-5 is one of the key cytokines responsible for eosinopoiesis in the bone marrow, along with recruitment and survival of eosinophils in the tissues. In view of this, IL-5 has been an attractive target for the development of anti-IL-5 monoclonal antibodies, inhibiting its action. The results of preclinical studies are viewed as encouraging. Preclinical development involved studies in mice, guinea-pigs and cynomolgus monkeys, with conflicting results in terms of changes in blood and bronchoalveolar lavage eosinophils, AHR and pulmonary resistance. These may be attributed to interspecies differences and to the different models used. Monoclonal antibodies directed against IL-5 have been used in at least four studies involving patients with asthma. Those preliminary studies have shown clear reductions in both blood and sputum eosinophils but no significant changes in physiological parameters of AHR, the late asthmatic reaction or in lung function or symptoms. As in the animal studies, these results suggest a dissociation between eosinophils, AHR, lung function and symptoms of asthma, which may be explained by the multitude of cells involved in the pathogenesis of asthma.

U.S. and European severe asthma cohorts: what can they teach us about severe asthma?

Asthma is a global health problem affecting around 300 million patients of all ages and ethnic groups in all countries around the world. In the majority of subjects with persistent, mild-to-moderate asthma (MA), the disease can be relatively well controlled by the use of currently available medications; however, five to ten per cent of patients suffer from a particularly severe disease that is poorly controlled clinically and often refractory to usual treatment. Improved care of severe asthma (SA) is a major unmet medical need and several international consortia aim at improving our understanding of mechanisms in SA. To manage SA better, standardized definitions and concepts of asthma severity, risk and level of control are critical. In the following sections, we present several guidelines approaches and definitions followed by an overview of U.S. (SARP) and European (ENFUMOSA, BIOAIR, U-BIOPRED) SA networks. Key findings regarding SA phenotypes, risk factors and pathophysiology are discussed. International cooperation in the area of respiratory diseases, including SA, across the Atlantic Ocean, will lead to a better understanding of asthma pathology, especially of those severe, not well controlled or difficult-to-treat cases.

How to diagnose and phenotype asthma

Asthma has been described as a chronic disease of the airways characterized by variable airflow obstruction, airway hyperresponsiveness, and airway inflammation. This review discusses the diagnosis and phenotyping of asthma, with a special emphasis on phenotyping based on the nature of cellular inflammation and radiological imaging and how this could be used to direct the treatment of asthma and, in the future, to apply specifically directed therapies to specific phenotypes.

Feasibility and acceptability of using bronchial hyperresponsiveness to manage asthma in primary care: a pilot study

AIMS

To determine if indirect testing for bronchial hyperresponsiveness (BHR) to monitor inhaled corticosteroid (ICS) treatment in asthma is feasible and acceptable in primary care.

METHODS

Fourteen adult patients with asthma aged 22-70 years (4M:10F, forced expiratory volume in 1 s >70% predicted) taking ICS performed a test for BHR using mannitol on three visits 6 weeks apart. ICS dose adjustments were made based on the presence of BHR. The Asthma Quality of Life Questionnaire (AQLQ) and the Asthma Control Questionnaire were used at each visit. A semi structured interview at study exit assessed subject acceptability.

RESULTS

BHR did not return in those with no BHR at study entry (n=9) with decreasing ICS dose. Improvements in BHR with increasing ICS dose (n=5) were observed with clinically significant improvements in AQLQ (mean score increase >0.5, p=0.02). Feasibility and acceptability of BHR testing was demonstrated.

CONCLUSIONS

It is feasible and acceptable to perform BHR testing using mannitol to help identify patients with asthma who would benefit from ICS dose increases and those with no BHR who could have a dose reduction.

TRIAL REGISTRATION

Australia New Zealand Clinical Trial Registry ACTRN12610000807055.

Asthma outcomes: exacerbations

BACKGROUND

The goals of asthma treatment include preventing recurrent exacerbations. Yet there is no consensus about the terminology for describing or defining "exacerbation" or about how to characterize an episode's severity.

OBJECTIVE

National Institutes of Health institutes and other federal agencies convened an expert group to propose how asthma exacerbation should be assessed as a standardized asthma outcome in future asthma clinical research studies.

METHODS

We used comprehensive literature reviews and expert opinion to compile a list of asthma exacerbation outcomes and classified them as either core (required in future studies), supplemental (used according to study aims and standardized), or emerging (requiring validation and standardization). This work was discussed at a National Institutes of Health-organized workshop in March 2010 and finalized in September 2011.

RESULTS

No dominant definition of "exacerbation" was found. The most widely used definitions included 3 components, all related to treatment, rather than symptoms: (1) systemic use of corticosteroids, (2) asthma-specific emergency department visits or hospitalizations, and (3) use of short-acting β-agonists as quick-relief (sometimes referred to as "rescue" or "reliever") medications.

CONCLUSIONS

The working group participants propose that the definition of "asthma exacerbation" be "a worsening of asthma requiring the use of systemic corticosteroids to prevent a serious outcome." As core outcomes, they propose inclusion and separate reporting of several essential variables of an exacerbation. Furthermore, they propose the development of a standardized, component-based definition of "exacerbation" with clear thresholds of severity for each component.

Association between episodes of upper respiratory infection and exacerbations in adult patients with asthma

BACKGROUND

Asthma has several phenotypical features, including recurrent exacerbations and recurrent episodes of upper respiratory infection (URI).

PURPOSE

A retrospective study was performed to identify the characteristics of adult patients with recurrent exacerbations of asthma, especially in association with recurrent episodes of URI.

METHODS

Information was collected using a self-administered questionnaire given to 7070 patients in autumn-winter 2006, 4859 patients in spring-summer 2007, and 4452 patients in autumn-winter 2007. The patients reported the degree of symptoms and the frequency of febrile episodes of URI and exacerbations. Severe exacerbations were defined as a self-report of asthma-related hospitalization, an emergency department visit, or a requirement for systemic corticosteroids. Recurrent febrile URI and exacerbations were defined as two or more episodes within the previous 6 months. A Poisson regression model was used to identify the factors that were predictors of a risk for exacerbations.

RESULTS

Of the 6266 patients who completed the questionnaire, the frequencies of febrile URI and episodes of severe exacerbations were 1.54 and 0.54 per subject per year, respectively. Logistic regression analysis showed that an older age [odds ratio (OR): 1.57; 95% confidence interval (CI): 1.15-2.13], female sex (OR: 1.58; 95% CI: 1.20-2.08), recurrent febrile episodes of URI (OR: 2.68; 95% CI: 1.47-4.91), a history of previous exacerbation within 1 year (OR: 1.74; 95% CI: 1.28-2.34), disuse of inhaled corticosteroids (ICSs) (OR: 2.63; 95% CI: 1.68-4.12), and disuse of add-on leukotriene receptor antagonists (LTRAs) (OR: 1.42; 95% CI: 1.06-1.74) were independently associated with moderate to severe symptom-severity. Poisson regression analysis showed that the independent factors that contributed to the frequency of recurrent severe exacerbations were female sex (regression coefficient β = 0.62, p < .01), an episode of sputum with coughing (β = 1.23, p < .01), nocturnal awakening (β = 1.22, p < .01), and severe exacerbation (β = 0.78, p < .01) within the previous 6 months.

CONCLUSION

Symptom-severity of asthma and the frequency of severe exacerbations were associated with previous exacerbations and susceptibility to URI.

Is FENO50 useful diagnostic tool in suspected asthma?

BACKGROUND

Asthma diagnosis is based on the presence of symptoms and the demonstration of airflow variability. Airway inflammation measured by fractional exhaled nitric oxide, measured at a flow rate of 50 ml/s (FE(NO50)) remains a controversial diagnostic tool.

AIM

To assess the ability of FE(NO50) to identify bronchial hyperresponsiveness (BHR) to methacholine (provocative concentration of methacholine causing a 20% fall in FEV(1); PC20M ≤ 16 mg/ml) and to establish whether or not symptoms relate to FE(NO50) and PC20M in patients with no demonstrated reversibility to β(2) -agonist.

METHODS

We conducted a prospective study on 174 steroid naive patients with respiratory symptoms, forced expiratory volume in 1 s (FEV(1) ) ≥ 70% predicted and no demonstrated reversibility to β(2) -agonist. Patients answered to a standardised symptom questionnaire and underwent FE(NO50) and methacholine challenge. Receiver-operating characteristic (ROC) curve and logistic regression analysis assessed the relationship between PC20M and FE(NO50) , taking into account covariates (smoking, atopy, age, gender and FEV(1)).

RESULTS

A total of 82 patients had a PC20M ≤ 16 mg/ml and had significantly higher FE(NO50) (19 ppb vs. 15 ppb; p < 0.05). By constructing ROC curve, we found that FE(NO50) cut-off value of 34 ppb was able to identify not only BHR with high specificity (95%) and positive predictive value (88%) but low sensitivity (35%) and negative predictive value (62%). When combining all variables into the logistic model, FE(NO50) (p = 0.0011) and FEV(1) (p < 0.0001) were independent predictors of BHR whereas age, gender, smoking and atopy had no influence. The presence of diurnal and nocturnal wheezing was associated with raised FE(NO50) (p < 0.001 and p < 0.05, respectively).

CONCLUSION

The value of FE(NO50) > 34 ppb has high predictive value of PC20M < 16 in patients with suspected asthma in whom bronchodilating test failed to demonstrate reversibility or was not indicated. However, FE(NO50) ≤ 34 ppb does not rule out BHR and should prompt the clinician to ask for a methacholine challenge.

Asthma outcome measures

Asthma is a common chronic disease with underlying inflammation of the airway. Advances in science have led to increased understanding of the heterogeneous nature of asthma and its complex mechanisms. Traditionally, asthma-practice guidelines have focused on optimizing lung function and the US FDA has required increases in lung function and reduction of exacerbation as primary outcomes in clinical trials of new asthma therapeutics. Improved lung function is a critical indicator of bronchodilator therapy, but the importance of long-term asthma control while maintained on controller medication is increasingly emphasized. The NIH asthma guidelines suggest the use of patient-reported outcomes, including health-related quality-of-life measures, to assess asthma control. Clinical practices and research studies concerning asthma can benefit from harmonizing the major outcome measures so that comparisons across studies can be made. In this article, we review common asthma outcome measures with a focus on recent efforts to harmonize outcomes for therapeutic clinical trials in asthma.

An official ATS clinical practice guideline: interpretation of exhaled nitric oxide levels (FENO) for clinical applications

BACKGROUND

Measurement of fractional nitric oxide (NO) concentration in exhaled breath (Fe(NO)) is a quantitative, noninvasive, simple, and safe method of measuring airway inflammation that provides a complementary tool to other ways of assessing airways disease, including asthma. While Fe(NO) measurement has been standardized, there is currently no reference guideline for practicing health care providers to guide them in the appropriate use and interpretation of Fe(NO) in clinical practice.

PURPOSE

To develop evidence-based guidelines for the interpretation of Fe(NO) measurements that incorporate evidence that has accumulated over the past decade.

METHODS

We created a multidisciplinary committee with expertise in the clinical care, clinical science, or basic science of airway disease and/or NO. The committee identified important clinical questions, synthesized the evidence, and formulated recommendations. Recommendations were developed using pragmatic systematic reviews of the literature and the GRADE approach.

RESULTS

The evidence related to the use of Fe(NO) measurements is reviewed and clinical practice recommendations are provided.

CONCLUSIONS

In the setting of chronic inflammatory airway disease including asthma, conventional tests such as FEV(1) reversibility or provocation tests are only indirectly associated with airway inflammation. Fe(NO) offers added advantages for patient care including, but not limited to (1) detecting of eosinophilic airway inflammation, (2) determining the likelihood of corticosteroid responsiveness, (3) monitoring of airway inflammation to determine the potential need for corticosteroid, and (4) unmasking of otherwise unsuspected nonadherence to corticosteroid therapy.

Effect of radiological extent and severity of bronchiectasis on pulmonary function

Background

The aim of this study was to ascertain the effect of the extent and severity of bronchiectasis as determined with high-resolution computed tomography (HRCT) on lung function in patients with pure bronchiectasis, bronchiectasis and asthma, and bronchiectasis and chronic obstructive pulmonary disease (COPD).

Methods

One hundred nineteen patients (71 with pure bronchiectasis, 25 asthmatic patients with bronchiectasis, and 23 COPD patients with bronchiectasis) underwent HRCT and pulmonary function tests. Computed tomography features were scored by the consensus of 2 radiologists.

Results

There were no statistically significant differences among the 3 patient groups regarding the extent of bronchiectasis, bronchial dilatation degree, bronchial wall thickening, decreased attenuation in the lung parenchyma, or presence of mucus in the large and small airways. In the pure bronchiectasis group, a negative correlation was found between forced vital capacity (FVC) % of predicted, forced expiratory volume in 1 sec (FEV₁) % of predicted, the FEV₁/FVC ratio and the extent of bronchiectasis, bronchial wall thickening, bronchial wall dilatation, and decreased attenuation. At multivariate analysis the main morphologic changes associated with impairment of FVC and FEV₁ were the extent of bronchiectasis and a decreased attenuation in the lung parenchyma. The decrease in the FEV₁/FVC ratio was associated with bronchial wall dilatation. No correlation was found between morphologic changes and indices of pulmonary function in the asthma and COPD patients.

Conclusions

Morphologic changes associated with bronchiectasis do not influence lung function in patients with asthma and COPD directly, although they do play a role in impairing pulmonary function in patients with bronchiectasis alone.

Human asthma phenotypes: from the clinic, to cytokines, and back again

A large body of experimental evidence supports the hypothesis that T-helper 2 (Th2) cytokines orchestrate allergic airway inflammation in animal models. However, human asthma is heterogeneous with respect to clinical features, cellular sources of inflammation, and response to common therapies. This disease heterogeneity has been investigated using sputum cytology as well as unbiased clustering approaches using cellular and clinical data. Important differences in cytokine-driven inflammation may underlie this heterogeneity, and studies in human subjects with asthma have begun to elucidate these molecular differences. This molecular heterogeneity may be assessed by existing biomarkers (induced sputum evaluation or exhaled nitric oxide testing) or may require novel biomarkers. Effective testing and application of emerging therapies that target Th2 cytokines will depend on accurate and easily obtained biomarkers of this molecular heterogeneity in asthma. Furthermore, whether other non-Th2 cytokine pathways underlie airway inflammation in specific subsets of patients with asthma is an unresolved question and an important goal of future research using both mouse models and human studies.

Asthma phenotypes in adults and clinical implications

It is becoming increasingly recognized that asthma is a heterogeneous disease, whether based on clinical factors, including the patient's age at diagnosis, symptom spectrum and treatment response, triggering factors, or the level and type of inflammation. Attempts to analyze the importance of these characteristics to the clinical presentation of asthma have led to the appreciation of numerous separate and overlapping asthma phenotypes. However, these approaches are 'biased' and based on the clinician/scientist's own experience. Recently, unbiased approaches have also been attempted using both molecular and statistical tools. Early results from these approaches have supported and expanded on the clinician's concepts. However, until specific biologic markers are identified for any of these proposed phenotypes, the definitive nature of any phenotype will remain speculative.

Using biomarkers in the assessment of airways disease

A biomarker provides a window on underlying disease activity. This is helpful when the pathology, treatment response, or both are heterogeneous or when trying to interpret nonspecific respiratory symptoms in patients with comorbidities. The successful application of a biomarker result is critically dependent on the specific question being addressed and the performance characteristics of the biomarker in relation to that question in the context of pretest probabilities. Negative prediction might be the best way to use a biomarker, such as a D-dimer, pro-brain natriuretic peptide, and exhaled nitric oxide. In this review the role of biomarkers in airways disease (notably induced sputum eosinophils and exhaled nitric oxide) is considered in relation to risk stratification, identification of treatment responders, identification of a clinical phenotype, monitoring of disease, and new drug development.

Respiratory sensitization: advances in assessing the risk of respiratory inflammation and irritation

Respiratory sensitization provides a case study for a new approach to chemical safety evaluation, as the prevalence of respiratory sensitization has increased considerably over the last decades, but animal and/or human experimental/predictive models are not currently available. Therefore, the goal of a working group was to design a road map to develop an ASAT approach for respiratory sensitisers. This approach should aim at (i) creating a database on respiratory functional biology and toxicology, (ii) applying data analyses to understand the multi-dimensional sensitization response, and how this predisposes to respiratory inflammation and irritation, and (iii) building a systems model out of these analyses, adding pharmacokinetic-pharmacodynamic modeling to predict respiratory responses to low levels of sensitisers. To this end, the best way forward would be to follow an integrated testing approach. Experimental research should be targeted to (i) QSAR-type approaches to relate potential as a respiratory sensitizer to its chemical structure, (ii) in vitro models and (iii) in vitro-in vivo extrapolation/validation.

The multiple dimensions of airways disease: targeting treatment to clinical phenotypes

PURPOSE OF REVIEW

The recognition that asthma and chronic obstructive pulmonary disease (COPD) are not single diseases, but syndromes made up of multiple separate disorders that overlap, has led to attempts to develop a new taxonomy for the disorders of airflow obstruction. A better understanding of the distinct disorders of airways disease has the potential to inform on underlying mechanisms, risk factors, natural history, monitoring and treatment.

RECENT FINDINGS

Recent attempts to describe the different phenotypes have largely been based on cluster analysis. Preliminary evidence suggests that there may be five distinct phenotypes of airways disease. To date, however, no simple allocation criteria have been validated that enable clinicians to allocate individual patients to specific phenotypic groups. The concept of differential treatment responses in different phenotypes of airways disease has been established with the demonstration that eosinophilic asthma preferentially responds to inhaled corticosteroid therapy or monoclonal antibody against interleukin-5, and severe refractory noneosinophilic asthma to macrolide antibiotics.

SUMMARY

The priority is to further define the distinct phenotypes that make up the syndromes of asthma and COPD. This knowledge could lead to treatments specifically targeted for defined phenotypic groups, rather than for asthma and COPD in general, which represents the current management approach.

Preventing asthma exacerbations: what are the targets?

Exacerbations of asthma are the main cause of asthma morbidity. They induce acute respiratory failure, and sometimes death. Two immunological signals acting in synergy are necessary for inducing asthma exacerbations. The first, triggered by allergens and/or unknown agents leads to the chronic Th2 inflammation characteristic of asthma. The second, caused by either viral infection, allergens, pollutants or a combination of these, results in an acute Th1 and Th2 inflammation precipitating symptoms. In both, innate and adaptive immunities are involved, providing a series of potential targets for therapy. Molecules associated to the first, chronic inflammation constitute targets for preventing therapies, when these related to the second, acute signal provide the rationale for curative treatments. Toll like receptors and bronchial epithelial cell-derived cytokines, engaged upstream of inflammation constitute interesting candidates for future treatments. The great heterogeneity of asthma has to be taken into account when considering targets for therapy to identify clusters of responders and nonresponders, and an integrative system biology approach will be necessary to go further.

Predictors of airway hyperresponsiveness differ between old and young patients with asthma

BACKGROUND

Age-related increases in morbidity and mortality due to asthma may be due to changes in pathophysiology as patients with asthma get older. There is limited knowledge about the effects of age on the predictors of airway hyperresponsiveness (AHR), a key feature of asthma. The aim of this study was to determine if the pathophysiologic predictors of AHR, including inflammation, ventilation heterogeneity, and airway closure, differed between young and old patients with asthma.

METHODS

Sixty-one young (18-46 years) and 43 old (50-80 years) patients with asthma had lung function, lung volumes, fraction of exhaled nitric oxide, ventilation heterogeneity, and airway responsiveness to methacholine measured. Airway response to methacholine was measured by the dose-response slope, as the percent fall in FEV(1) per micromole of methacholine. Indices of ventilation heterogeneity were calculated for convection-dependent and diffusion-dependent airways.

RESULTS

In young patients with asthma, the independent predictors of AHR were convection-dependent ventilation heterogeneity, exhaled nitric oxide, and % predicted FEV(1)/FVC (model r(2) = 0.51, P < .0001). In old patients with asthma, the independent predictors of airway responsiveness were % predicted residual volume, diffusion-dependent ventilation heterogeneity, and % predicted FEV(1) (model r(2) = 0.57, P < .0001).

CONCLUSIONS

In old patients with asthma, AHR is predicted by gas trapping and ventilation heterogeneity in peripheral, diffusion-dependent airways. In the young, it is predicted by ventilation heterogeneity in less peripheral conducting airways and by inflammation. These findings suggest that there are differences in the pathophysiologic determinants of AHR between young and old patients with asthma.

Overcoming heterogeneity in pediatric asthma: tobacco smoke and asthma characteristics within phenotypic clusters in an African American cohort

OBJECTIVE

Asthma in children and adolescents is a heterogeneous syndrome comprised of multiple subgroups with variable disease expression and response to environmental exposures. The goal of this study was to define homogeneous phenotypic clusters within a cohort of children and adolescents with asthma and to determine overall and within-cluster associations between environmental tobacco smoke (ETS) exposure and asthma characteristics.

METHODS

A combined hierarchical/k-means cluster analysis of principal component variables was used to define phenotypic clusters within a cohort of 6- to 20-year-old urban and largely minority subjects.

RESULTS

Among the 154 subjects, phenotypic cluster analysis defined three independent clusters (Cluster 1 [n = 57]; Cluster 2 [n = 33]; Cluster 3 [n = 58]). A small fourth cluster (n = 6) was excluded. Patients in Cluster 1 were predominantly males, with a relative abundance of neutrophils in their nasal washes. Patients in Cluster 2 were predominantly females with high body mass index percentiles and later-onset asthma. Patients in Cluster 3 had higher eosinophil counts in their nasal washes and lower Asthma Control Test (ACT) scores. Within-cluster regression analysis revealed several significant associations between ETS exposure and phenotypic characteristics that were not present in the overall cohort. ETS exposure was associated with a significant increase in nasal wash neutrophils (beta coefficient = 0.73 [95% confidence interval, CI: 0.11 to 1.35]; p = .023) and a significant decrease in ACT score (-5.17 [-8.42 to -1.93]; p = .003) within Cluster 1 and a significant reduction in the bronchodilator-induced % change in forced expiratory volume in one second (FEV(1)) (-36.32 [-62.18 to -10.46]; p = .009) within Cluster 3.

CONCLUSIONS

Clustering techniques defined more homogeneous subgroups, allowing for the detection of otherwise undetectable associations between environmental tobacco smoke exposure and asthma characteristics.

Bronchial hyperresponsiveness in the assessment of asthma control: Airway hyperresponsiveness in asthma: its measurement and clinical significance

The two key pathophysiologic features of asthma are bronchial hyperresponsiveness (BHR) and airway inflammation. Symptoms and lung function are the most accessible clinical markers for the diagnosis of asthma as well as for assessing asthma control using the most effective treatment of asthma, inhaled corticosteroids (ICS). However, BHR and inflammation usually take longer to resolve using ICS compared with symptoms and lung function. BHR can be assessed using "direct" stimuli that act on the airway smooth muscle (eg, methacholine) or "indirect" stimuli that require the presence of airway inflammation (eg, exercise, osmotic stimuli). Although there are practical limitations in using BHR to assess asthma control, efforts have been made to make BHR more accessible and standardized. Some studies have demonstrated that treatment aimed to decrease BHR with direct stimuli can lead to improved asthma control; however, it often results in the use of higher doses of ICS. Furthermore, BHR to direct stimuli does not usually resolve using ICS because of a fixed component. By contrast, BHR with an indirect stimulus indicates a responsive smooth muscle that occurs only in the presence of inflammation sensitive to ICS (eg, mast cells, eosinophils). BHR to indirect stimuli does resolve using ICS. Because ICS target both key pathophysiologic features of asthma, assessing indirect BHR in the presence of ICS will identify resolution or persistence of BHR and airway inflammation. This may provide a more clinically relevant marker for asthma control that may also lead to improving the clinical usefulness of ICS.

Biomarkers in asthma and allergic rhinitis

A biological marker (biomarker) is a physical sign or laboratory measurement that can serve as an indicator of biological or pathophysiological processes or as a response to a therapeutic intervention. An applicable biomarker possesses the characteristics of clinical relevance (sensitivity and specificity for the disease) and is responsive to treatment effects, in combination with simplicity, reliability and repeatability of the sampling technique. Presently, there are several biomarkers for asthma and allergic rhinitis that can be obtained by non-invasive or semi-invasive airway sampling methods meeting at least some of these criteria. In clinical practice, such biomarkers can provide complementary information to conventional disease markers, including clinical signs, spirometry and PC(20)methacholine or histamine. Consequently, biomarkers can aid to establish the diagnosis, in staging and monitoring of the disease activity/progression or in predicting or monitoring of a treatment response. Especially in (young) children, reliable, non-invasive biomarkers would be valuable. Apart from diagnostic purposes, biomarkers can also be used as (surrogate) markers to predict a (novel) drug's efficacy in target populations. Therefore, biomarkers are increasingly applied in early drug development. When implementing biomarkers in clinical practice or trials of asthma and allergic rhinitis, it is important to consider the heterogeneous nature of the inflammatory response which should direct the selection of adequate biomarkers. Some biomarker sampling techniques await further development and/or validation, and should therefore be applied as a "back up" of established biomarkers or methods. In addition, some biomarkers or sampling techniques are less suitable for (very young) children. Hence, on a case by case basis, a decision needs to be made what biomarker is adequate for the target population or purpose pursued. Future development of more sophisticated sampling methods and quantification techniques, such as--omics and biomedical imaging, will enable detection of adequate biomarkers for both clinical and research applications.

Montelukast in the treatment of asthma and beyond

Asthma is a chronic inflammatory disease affecting over 300 million people worldwide. The common association with allergic rhinitis and the presence of proinflammatory cells and mediators in the circulation of patients qualify asthma as a systemic disease. This characteristic and the fact that the gold-standard therapy for persistent asthma, inhaled corticosteroids, cannot suppress all components of airway inflammation and fail to adequately penetrate into the small airways, warrant the quest for effective systemic anti-asthma therapies. This review describes the most important controlled studies of montelukast, a once-daily leukotriene receptor antagonist, in asthma and allergic rhinitis in both adults and children. Montelukast is a systemically active drug with a targeted, dual mechanism of action, acting both as a bronchodilator and anti-inflammatory. In patients of all ages, montelukast has shown a favorable safety profile and was well-tolerated. Both as monotherapy or in combination with inhaled corticosteroids, montelukast produced clinically relevant improvements in asthma-related parameters, including symptoms, lung function parameters, quality of life and the number of asthma exacerbations. Furthermore, bronchoprotective effects have been reported both against specific and nonspecific bronchoactive stimuli. Similarly, in patients with allergic rhinitis, montelukast produced substantial improvements in symptoms and quality of life. Long-term studies aimed to determine its effects on airway remodeling are still lacking.

Identification of asthma phenotypes using cluster analysis in the Severe Asthma Research Program

RATIONALE

The Severe Asthma Research Program cohort includes subjects with persistent asthma who have undergone detailed phenotypic characterization. Previous univariate methods compared features of mild, moderate, and severe asthma.

OBJECTIVES

To identify novel asthma phenotypes using an unsupervised hierarchical cluster analysis.

METHODS

Reduction of the initial 628 variables to 34 core variables was achieved by elimination of redundant data and transformation of categorical variables into ranked ordinal composite variables. Cluster analysis was performed on 726 subjects.

MEASUREMENTS AND MAIN RESULTS

Five groups were identified. Subjects in Cluster 1 (n = 110) have early onset atopic asthma with normal lung function treated with two or fewer controller medications (82%) and minimal health care utilization. Cluster 2 (n = 321) consists of subjects with early-onset atopic asthma and preserved lung function but increased medication requirements (29% on three or more medications) and health care utilization. Cluster 3 (n = 59) is a unique group of mostly older obese women with late-onset nonatopic asthma, moderate reductions in FEV(1), and frequent oral corticosteroid use to manage exacerbations. Subjects in Clusters 4 (n = 120) and 5 (n = 116) have severe airflow obstruction with bronchodilator responsiveness but differ in to their ability to attain normal lung function, age of asthma onset, atopic status, and use of oral corticosteroids.

CONCLUSIONS

Five distinct clinical phenotypes of asthma have been identified using unsupervised hierarchical cluster analysis. All clusters contain subjects who meet the American Thoracic Society definition of severe asthma, which supports clinical heterogeneity in asthma and the need for new approaches for the classification of disease severity in asthma.

Overall asthma control: the relationship between current control and future risk

BACKGROUND

Asthma guidelines emphasize both maintaining current control and reducing future risk, but the relationship between these 2 targets is not well understood.

OBJECTIVE

This retrospective analysis of 5 budesonide/formoterol maintenance and reliever therapy (Symbicort SMART Turbuhaler(*)) studies assessed the relationship between asthma control questionnaire (ACQ-5) and Global Initiative for Asthma-defined clinical asthma control and future risk of instability and exacerbations.

METHODS

The percentage of patients with Global Initiative for Asthma-defined controlled asthma over time was assessed for budesonide/formoterol maintenance and reliever therapy versus the 3 maintenance therapies; higher dose inhaled corticosteroid (ICS), same dose ICS/long-acting beta(2)-agonist (LABA), and higher dose ICS/LABA plus short-acting beta(2)-agonist. The relationship between baseline ACQ-5 and exacerbations was investigated. A Markov analysis examined the transitional probability of change in control status throughout the studies.

RESULTS

The percentage of patients achieving asthma control increased with time, irrespective of treatment; the percentage Controlled/Partly Controlled at study end was at least similar to budesonide/formoterol maintenance and reliever therapy versus the 3 maintenance therapies: higher dose ICS (56% vs 45%), same dose ICS/LABA (56% vs 53%), and higher dose ICS/LABA (54% vs 54%). Baseline ACQ-5 score correlated positively with exacerbation rates. A Controlled or Partly Controlled week predicted at least Partly Controlled asthma the following week (>or=80% probability). The better the control, the lower the risk of an Uncontrolled week. The probability of an exacerbation was related to current state and was lower with budesonide/formoterol maintenance and reliever therapy.

CONCLUSIONS

Current control predicts future risk of instability and exacerbations. Budesonide/formoterol maintenance and reliever therapy reduces exacerbations versus comparators and achieves at least similar control.