Simultaneously elevated FeNO and blood eosinophils relate to asthma morbidity in asthmatics from NHANES 2007-12

Prediction of Asthma Exacerbations in Children

Asthma exacerbations are common in asthmatic children, even among those with good disease control. Asthma attacks result in the children and their parents missing school and work days; limit the patient's social and physical activities; and lead to emergency department visits, hospital admissions, or even fatal events. Thus, the prompt identification of asthmatic children at risk for exacerbation is crucial, as it may allow for proactive measures that could prevent these episodes. Children prone to asthma exacerbation are a heterogeneous group; various demographic factors such as younger age, ethnic group, low family income, clinical parameters (history of an exacerbation in the past 12 months, poor asthma control, poor adherence to treatment, comorbidities), Th2 inflammation, and environmental exposures (pollutants, stress, viral and bacterial pathogens) determine the risk of a future exacerbation and should be carefully considered. This paper aims to review the existing evidence regarding the predictors of asthma exacerbations in children and offer practical monitoring guidance for promptly recognizing patients at risk.

Update on the Role of FeNO in Asthma Management

Asthma is a heterogenous disorder characterized by presence of different phenotypes and endotypes. Up to 10% of the individuals suffer from severe asthma and are at increased risk of morbidity and mortality. Fractional exhaled nitric oxide (FeNO) is a cost-effective, point of care biomarker that is used to detect type 2 airway inflammation. Guidelines have proposed to measure FeNO as an adjunct to diagnostic evaluation in individuals with suspected asthma and to monitor airway inflammation. FeNO has lower sensitivity, suggesting that it may not be a good biomarker to rule out asthma. FeNO may also be used to predict response to inhaled corticosteroids, predict adherence and deciding on biologic therapy. Higher levels of FeNO have been associated with lower lung function and increased risk for future asthma exacerbations and its predictive value increases when combined with other standard measurements of asthma assessment.

Distribution of type 2 biomarkers and association with severity, clinical characteristics and comorbidities in the BREATHE real-life asthma population

Background

Type 2 (T2) high asthma is recognised as a heterogenous entity consisting of several endotypes; however, the prevalence and distribution of the T2 biomarkers in the general asthma population, across asthma severity, and across compartments is largely unknown. The objective of the present study was to describe expression and overlaps of airway and systemic T2 biomarkers in a clinically representative asthma population.

Methods

Patients with asthma from the real-life BREATHE cohort referred to a specialist centre were included and grouped according to T2 biomarkers: blood and sputum eosinophilia (≥0.3×10⁹ cells·L^-1 and 3% respectively), total IgE (≥150 U·mL^-1), and fractional exhaled nitric oxide (≥25 ppb).

Results

Patients with mild-to-moderate asthma were younger (41 versus 49 years, p<0.001), had lower body mass index (25.9 versus 28.0 kg·m^-2, p=0.002) and less atopy (47% versus 58%, p=0.05), higher forced expiratory volume in 1 s (3.2 versus 2.8 L, p<0.001) and forced vital capacity (4.3 versus 3.9 L, p<0.001) compared with patients with severe asthma, who had higher blood (0.22×10⁹ versus 0.17×10⁹ cells·L^-1, p=0.01) and sputum (3.0% versus 1.5%, p=0.01) eosinophils. Co-expression of all T2 biomarkers was a particular characteristic of severe asthma (p<0.001). In patients with eosinophilia, sputum eosinophilia without blood eosinophilia was present in 45% of patients with mild-to-moderate asthma and 35% with severe asthma.

Conclusion

Severe asthma is more commonly associated with activation of several T2 pathways, indicating that treatments targeting severe asthma may need to act more broadly on T2 inflammatory pathways. Implementation of airway inflammometry in clinical care is of paramount importance, as the best treatable trait is otherwise is overlooked in a large proportion of patients irrespective of disease severity.

Association of general and abdominal obesity with lung function, FeNO, and blood eosinophils in adult asthmatics: Findings from NHANES 2007-2012

Purpose: Obesity is considered a risk factor for asthma exacerbation. However, limited studies have focused on the association of different levels of weight clusters with asthma. As such, we study the associations between different weight clusters with FeNO, blood eosinophils, and lung function among adult asthmatics. Methods: Data from 789 participants aged 20 years or older in the National Health and Nutrition Examination Survey 2007-2012 were analyzed. Body mass index (BMI) and waist circumference (WC) were used to determine the weight status. The study population was divided into five groups, including normal weight and low WC (153), normal weight and high WC (43), overweight and high WC (67), overweight and abdominal obesity (128), and general and abdominal obesity (398). A Multivariate linear regression model was used to evaluate the abovementioned associations after adjusting for potential confounding factors. Results: The adjusted models showed that general and abdominal obesity cluster (adjusted β = -0.63, 95% confidence interval (CI): -1.08, -0.17 p < 0.01), and the normal weight with high WC cluster (adjusted β = -0.96, 95% CI: -1.74, -0.19 p < 0.05) were associated with lower levels of blood eosinophils percentage than normal weight and low WC cluster. A similar tendency was shown in the levels of FeNO, but the differences were not significant (p > 0.05). Furthermore, abdominal obesity clusters were significantly associated with lower FVC, FVC% predicted, and FEV₁ measures than normal weight and low WC cluster, especially those individuals with general and abdominal obesity cluster. No association was found between different weight clusters and FEV₁/FVCF ratio. The two other weight clusters did not show the association with any of the lung function measures. Conclusion: General and abdominal obesity were associated with lung function impairment and a significant reduction of FeNO and blood eosinophil percentage. This study emphasized the importance of concurrent determination of BMI and WC in asthma clinical practice.

Expert Opinion on Practice Patterns in Mild Asthma After the GINA 2019 Updates: A Major Shift in Treatment Paradigms from a Long-Standing SABA-Only Approach to a Risk Reduction-Based Strategy with the Use of Symptom-Driven (As-Needed) Low-Dose ICS/LABA

PURPOSE OF REVIEW

This expert opinion, prepared by a panel of chest disease specialists, aims to review the current knowledge on practice patterns in real-life management of mild asthma and to address the relevant updates in asthma treatment by The Global Initiative for Asthma (GINA) to guide clinicians for the best clinical practice in applying these new treatment paradigms.

RECENT FINDINGS

On the basis of the emerging body of evidence suggesting the non-safety of short-acting β2-agonists (SABA)-only therapy and comparable efficacy of the as-needed inhaled corticosteroids (ICS)-formoterol combinations with maintenance ICS regimens, GINA recently released their updated Global Strategy for Asthma Management and Prevention Guide (2019). The new GINA 2019 recommendations no longer support the SABA-only therapy in mild asthma but instead includes new off-label recommendations such as symptom-driven (as-needed) low-dose ICS-formoterol and "low dose ICS taken whenever SABA is taken." The GINA 2019 asthma treatment recommendations include a major shift from long-standing approach of clinical practice regarding the use of symptom-driven SABA treatment alone in the management of mild asthma. This expert opinion supports the transition from a long-standing SABA-only approach to a risk reduction-based strategy, with the use of symptom-driven (as-needed) low-dose ICS/LABA in mild asthma patients, particularly in those with poor adherence to controller medications. The thoughtful and comprehensive approach of clinicians to these strategies is important, given that the exact far-reaching impact of this major change in management of mild asthma in the real-world settings will only be clarified over time.

Eosinophilic airway diseases: basic science, clinical manifestations and future challenges

Eosinophils have a broad range of functions, both homeostatic and pathological, mediated through an array of cell surface receptors and specific secretory granules that promote interactions with their microenvironment. Eosinophil development, differentiation, activation, survival and recruitment are closely regulated by a number of type 2 cytokines, including interleukin (IL)-5, the key driver of eosinophilopoiesis. Evidence shows that type 2 inflammation, driven mainly by interleukin (IL)-4, IL-5 and IL-13, plays an important role in the pathophysiology of eosinophilic airway diseases, including asthma, chronic rhinosinusitis with nasal polyps, eosinophilic granulomatosis with polyangiitis and hypereosinophilic syndrome. Several biologic therapies have been developed to suppress type 2 inflammation, namely mepolizumab, reslizumab, benralizumab, dupilumab, omalizumab and tezepelumab. While these therapies have been associated with clinical benefits in a range of eosinophilic diseases, their development has highlighted several challenges and directions for future research. These include the need for further information on disease progression and identification of treatable traits, including clinical characteristics or biomarkers that will improve the prediction of treatment response. The Nordic countries have a long tradition of collaboration using patient registries and Nordic asthma registries provide unique opportunities to address these research questions. One example of such a registry is the NORdic Dataset for aSThmA Research (NORDSTAR), a longitudinal population-based dataset containing all 3.3 million individuals with asthma from four Nordic countries (Denmark, Finland, Norway and Sweden). Large-scale, real-world registry data such as those from Nordic countries may provide important information regarding the progression of eosinophilic asthma, in addition to clinical characteristics or biomarkers that could allow targeted treatment and ensure optimal patient outcomes.

FeNO in Asthma

Asthma is a common disease affecting 350 million people worldwide, which is characterized by airways inflammation and hyperreactivity. Historically diagnosis and treatment have been mainly based on symptoms, which have the potential to result in misdiagnosis and inappropriate treatment. Nitric oxide (NO) is exhaled in human breath and is a marker of airways inflammation. Levels of NO are increased in the exhaled breath of patients with type 2 asthma and fractional exhaled nitric oxide (FeNO) provides an objective biomarker of airway inflammation. FeNO testing is an accessible, noninvasive, and easy-to-use test. Cut-off values have been established by the American Thoracic Society (ATS), the Global Initiative for Asthma (GINA), and the National Institute for Health and Care Excellence (NICE) but vary between guidance. FeNO levels have been shown to be predictive of blood and sputum eosinophil levels but should not be used in isolation and current guidance emphasizes the importance of incorporating clinical symptoms and testing when utilizing FeNO results. The inclusion of FeNO testing can increase diagnostic accuracy of asthma, while high levels in asthmatic patients can help predict response to inhaled corticosteroids (ICS) and suppression of levels with ICS to monitor adherence. FeNO levels are also a predictor of asthma risk with increased exacerbation rates and accelerated decline in lung function associated with high levels as well as having an emerging role in predicting response to some biologic therapies in severe asthma. FeNO testing is cost-effective and has been shown, when combined with clinical assessment, to improve asthma management.

The Effect of Short Sleep Duration on the Development of Asthma

Asthma is regarded as a heterogeneous disease with chronic airway inflammation and reversible airway limitation. Asthma itself and recurrent attacks of asthma can decrease sleep duration and increase the prevalence of short sleep duration. Systemic low-grade inflammation and obesity caused by short sleep duration have been known for a long time, which potentially affect the development of asthma. It would be interesting to study the interaction between short sleep duration and asthma. However, there are relatively few studies and no review about the association between short sleep duration and asthma. This article performed a review about the relationships between short sleep duration and asthmatic phenotype, laboratory tests, comorbidity, and clinical outcomes. Pooled studies about short sleep duration and asthma provided following four results: (1) compared with healthy sleep duration, short sleep duration seemingly increased the risk of central obesity in asthmatics; (2) short sleep duration potentially reduced the level of FeNO and increased lung function impairment in patients with asthma; (3) asthmatic comorbidities, mainly obesity and depression, were negatively associated with short sleep duration among asthmatics; (4) short sleep duration potentially increased the risks of asthma-related hospitalization and emergency care. However, almost all studies are based on subjective but not objective sleep duration. In addition, the study on sleep duration and cause-specific mortality in patients with asthma is relatively scant. Considering the effect of short sleep duration on the development of asthma, we recommend that periodic sleep monitoring for asthmatic management is very necessary.

Diagnostic possibility of the combination of exhaled nitric oxide and blood eosinophil count for eosinophilic asthma

BACKGROUND

Tests to identify reversible airflow limitation are important in asthma diagnosis, but they are time-consuming and it may be difficult for patients to cooperate. We aimed to evaluate whether the combination of fractional exhaled nitric oxide (FeNO) and blood eosinophil (B-Eos) can be used to distinguish some asthma patients who could avoid objective tests.

METHODS

We conducted a retrospective cohort study on 7463 suspected asthma cases between January 2014 and December 2019 in Chongqing, China, and identified 2349 patients with complete FeNO, B-Eos count, and spirometry data. Asthma was diagnosed by clinicians by the criteria of recurrent respiratory symptoms and a positive bronchial-provocation or bronchodilation test (BPT, BPD). We evaluated the diagnostic accuracy of FeNO or B-Eos alone or both in combination for asthma using receiver operating characteristic (ROC) curve analysis.

RESULTS

In this study, 824 patients were diagnosed with asthma. When FeNO and B-Eos counts were used in combination, the area under the ROC curve (AUC) for diagnosing asthma increased slightly (0.768 vs. 0.745 [FeNO] or 0.728 [B-Eos]; both P < 0.001). The odds ratio for having asthma increased progressively with a gradual increase in FeNO or B-Eos count (both P < 0.001; assessed using the Cochran-Armitage trend test). Further analysis of in-series combinations of different threshold values for these biomarkers indicated that moderately elevated biomarker levels (FeNO > 40 ppb and B-Eos > 300 cells/μl) support a diagnosis of asthma because diagnostic specificity was > 95% and the positive likelihood ratio (PLR) was > 10. This conclusion was verified when selecting the 2017-2019 data as the internal validation dataset.

CONCLUSION

FeNO or B-Eos count alone is insufficient to accurately diagnose asthma. Patients with moderately elevated biomarkers (FeNO > 40 ppb and B-Eos > 300 cells/μl) could be diagnosed with asthma and avoid objective tests when such tests are not feasible.

Biomarkers of asthma

Biomarkers may be diagnostic of asthma, they may predict or reflect response to therapy or they may identify patients at risk of asthma exacerbation. A biomarker is most often measured in biologic fluids that are sampled using relatively non-invasive sampling techniques such as blood, sputum, urine or exhaled breath. Biomarkers should be stable, readily quantifiable and their measurement should be reproducible and not confounded by other host factors, or the presence of comorbidities. However, asthma comprises multiple molecular endotypes and single, sensitive, specific, biomarkers reflecting these endotypes may not exist. Combining biomarkers may improve their predictive capability in asthma. The most well-established endotypes are those described as Type2 and non-Type2 asthma. Clinical trials established the fraction of exhaled nitric oxide (FeNO) and blood eosinophil counts as key biomarkers of response to corticosteroid or targeted anti-inflammatory therapy in Type2 asthma. However, these biomarkers may have limited value in the management of asthma in real-life settings or routine clinical practise. Biomarkers for Type2 asthma are not well described or validated and more research is needed. Breathomics has provided evidence to propose a number of exhaled volatile organic compounds (VOCs) as surrogate biomarkers for airway inflammatory phenotypes, disease activity and adherence to therapy. Analysis of urinary eicosanoids has identified eicosanoids related to Type2 and non-Type2 inflammation. Future clinical trials will be important in determining how exhaled VOCs or urinary eicosanoid profiles can be used to direct precision treatments. Their future clinical use will also depend on developing simplified instrumentation for biomarker analysis at the point-of-care.

Systemic and breath biomarkers for asthma: an update

PURPOSE OF REVIEW

Finding suitable biomarkers to phenotype asthma, identify individuals at risk of worsening and guide treatment is highly prioritized in asthma research. We aimed to provide an analysis of currently used and upcoming biomarkers, focusing on developments published in the past 2 years.

RECENT FINDINGS

Type 2 inflammation is the most studied asthma mechanism with the most biomarkers in the pipeline. Blood eosinophils and fractional exhaled nitric oxide (FeNO) are those most used clinically. Recent developments include their ability to identify individuals at higher risk of exacerbations, faster decline in lung function and more likely to benefit from anti-IL-5 and anti-IL-4/-13 treatment. Certain patterns of urinary eicosanoid excretion also relate to type 2 inflammation. Results of recent trials investigating the use of serum periostin or dipeptidyl peptidase-4 to guide anti-IL-13 therapy were somewhat disappointing. Less is known about non-type 2 inflammation but blood neutrophils and YKL-40 may be higher in patients with evidence of non-type 2 asthma. Volatile organic compounds show promise in their ability to distinguish both eosinophilic and neutrophilic asthma.

SUMMARY

The ultimate panel of biomarkers for identification of activated inflammatory pathways and treatment strategies in asthma patients still lies in the future, particularly for non-type 2 asthma, but potential candidates are available.

Diagnosis and Management of T2-High Asthma

Type 2 (T2) inflammation plays a key role in the pathogenesis of asthma. IL-4, IL-5, and IL-13, along with other inflammatory mediators, lead to increased cellular eosinophilic inflammation. It is likely that around half of all patients with asthma have evidence of T2-high inflammation. Sputum and blood eosinophils, exhaled nitric oxide, blood IgE levels, and airway gene expression markers are frequently used biomarkers of T2-high asthma. Individuals with T2-high asthma tend to have several features of increased asthma severity, including reduced lung function and increased rates of asthma exacerbations, and T2-high patients demonstrate distinct pathologic features including increased airway remodeling and alterations in airway mucus production. Several monoclonal antibodies are now available to treat individuals with T2-high asthma and these medications significantly reduce asthma exacerbation rates.

Blood eosinophil count as predictor of asthma exacerbation. A meta-analysis

BACKGROUND

Evidence about the association of high blood eosinophil count with asthma exacerbation is inconsistent and unclear. The objective of this meta-analysis was to determine whether elevated blood eosinophil count predicts asthma exacerbation.

METHODS

We searched MEDLINE, EMBASE, and additional databases, without any language restriction. We also checked the reference lists of the included studies and of relevant systematic reviews. The main outcome was the occurrence of asthma exacerbation. We calculated global pooled odds ratios (ORs) and their 95% confidence intervals (CIs) and performed predefined subgroup analyses. We appraised the quality of the studies using Newcastle-Ottawa Scale, examined the heterogeneity between studies, assessed publication bias, and carried out sensitivity analyses.

RESULTS

Among 1567 retrieved publications, 23 observational studies comprising 155,772 participants met the inclusion criteria. High blood eosinophil count was associated with higher odds of asthma exacerbation [OR: 1.31 (95% CI: 1.16, 1.49)], specifically with asthma-related outpatient visits [OR: 1.46 (95% CI: 1.25, 1.70)] and emergency department visits [OR: 1.63 (95% CI: 1.29, 2.07)]. A significant association was observed starting from an eosinophils' cutoff value of 200 cells/μl. The association was observed for cohort studies [OR: 1.30 (95%CI: 1.13, 1.49)], North American studies [OR: 1.43 (95%CI: 1.31, 1.57)], Asian populations [OR: 1.67 (95%CI: 1.34, 2.08)], children [OR: 1.38 (95%CI: 1.22, 1.56)], and studies that adjusted for inhaled corticosteroids therapy [OR: 1.42 (95%CI: 1.28, 1.56)].

CONCLUSIONS

Blood eosinophil counts ≥ 200 cells/µL are associated with asthma exacerbation. Blood eosinophil count is a modifiable factor that could be addressed in asthma management strategies.

Associations between sleep duration, lung function, FeNO and blood eosinophils among current asthmatics (NHANES 2007-12)

Short sleep duration potentially affects the risk of developing asthma and asthmatic exacerbation. Our aim is to determine the associations between sleep duration with asthmatic phenotypes, fraction of exhaled NO (FeNO), blood eosinophils, and lung function among current asthmatics. A total of 558 individuals from the National Health and Nutrition Examination Survey during 2007-2012 were included in this study. Self-reported sleep duration was divided into three groups: short (⩽6 h), healthy (7-8 h) and long (⩾9 h). By using a multivariate generalized additive model with binomial or Poisson regression, the abovementioned associations were evaluated after adjustment for potential confounders. Our study population included 284 short sleepers, 240 healthy sleepers and 34 long sleepers. In multivariate binomial regression analysis, we found that short sleep duration was associated with increased risk of asthma with central obesity (adjusted OR = 0.58, 95%CI: 0.33-0.99, P = 0.047) compared with healthy sleep duration. Multivariate Poisson regression analyses revealed a significant increase in FeNO (adjusted OR = 1.19, 95%CI: 1.14-1.26, P < 0.01) and reduction of blood eosinophil percentage (adjusted OR = 0.86, 95%CI: 0.77-0.96, P < 0.01) in the healthy sleep duration group compared with the short sleep duration group. The individuals with healthy and long sleep duration harbored better lung function than those with short sleep duration, with the exception of FEV1/FVC. Our study suggested that short sleepers potentially increase the risk of asthma with central obesity and lung function impairment than healthy sleepers among current asthmatics. We also observed that short sleep duration is associated with a significant reduction of FeNO and increase of blood eosinophil percentage.

Inflammatory patterns in fixed airflow obstruction are dependent on the presence of asthma

RATIONALE

Fixed airflow obstruction (FAO) can complicate asthma. Inflammation is a proposed underlying mechanism.

OBJECTIVE

Our aim in this cross-sectional investigation was to evaluate the blood leucocyte pattern and level of exhaled nitric oxide in asthmatics and non-asthmatics with or without FAO.

METHODS

A total of 11,579 individuals aged ≥20 years from the US National Health and Nutrition Examination Survey were included. They were grouped as: controls without asthma and FAO (n = 9,935), asthmatics without FAO (n = 674), asthmatics with FAO (n = 180) and non-asthmatics with FAO (n = 790). FAO was defined as post-bronchodilator FEV1/FVC < lower limit of normal. Exhaled nitric oxide ≥ 25ppb, blood eosinophil levels ≥300 cells/μL, and blood neutrophil levels ≥5100 cells/μL were defined as elevated. Stratified analyses for smoking and smoking history were performed.

RESULTS

Elevated blood eosinophil levels were more common in all groups compared to the controls, with the highest prevalence in the group with asthma and fixed airflow obstruction (p<0.01). In a multiple logistic regression model adjusted for potential confounders including smoking, the asthma groups had significantly higher odds ratios for elevated B-Eos levels compared to the control group (odds ratio 1.4, (confidence interval: 1.1-1.7) for the asthma group without fixed airflow obstruction and 2.5 (1.4-4.2) for the asthma group with fixed airflow obstruction). The group with fixed airflow obstruction without asthma had higher odds ratio for elevated blood neutrophil levels compared to the controls: 1.4 (1.1-1.8). Smoking and a history of smoking were associated to elevated B-Neu levels.

CONCLUSION

Fixed airflow obstruction in asthma was associated with elevated blood eosinophil levels, whereas fixed airflow obstruction without asthma was associated with elevated blood neutrophil levels.

The Prevalence of Subtypes of Type 2 Inflammation in an Unselected Population of Patients with Severe Asthma

BACKGROUND

With the introduction of different targeted therapies for type 2 (T2)-high asthma, there is an urgent need for markers to guide the choice of treatment. T2-high asthma includes different clinical phenotypes of asthma, but the prevalence and impact of activation of different T2 inflammatory pathways is unknown.

OBJECTIVE

To describe the level of coexpression of clinically available T2 inflammatory markers in patients with severe asthma, and the relationship with clinical characteristics and comorbidities.

METHODS

Patients with severe asthma according to European Respiratory Society/American Thoracic Society guidelines were examined prospectively including sputum induction and grouped according to T2 biomarkers: blood eosinophilia (≥0.3 × 10⁹/L), total IgE (≥150 U/mL), and fractional exhaled nitric oxide (≥25 parts per billion).

RESULTS

We found 116 (70%) of the 166 patients to have at least 1 T2 biomarker elevated: 39% had 2 or more elevated biomarkers, whereas 31% had only 1 biomarker elevated. Concomitant airway and systemic eosinophilia was present in 28% of all patients, corresponding to half (53%) of the patients with either. Expression patterns of the T2 biomarkers were associated with differences in allergic sensitization and the coexistence of nasal polyposis.

CONCLUSIONS

Most patients with severe asthma showed at least 1 T2 inflammatory trait. Coexpression of T2 biomarkers was highly heterogeneous, and different expression patterns were associated with distinct clinical characteristics.

Blood eosinophil level and lung function trajectories: cross-sectional and longitudinal studies in European cohorts

Background

Elevated blood eosinophils have been associated with lower lung function and are believed to be associated with accelerated lung function decline.

Method

Blood eosinophils were measured in four cohorts: <45 years cohort within the Vlagtwedde–Vlaardingen (V&V) study, the Uppsala cohort of the European Community Respiratory Health Survey (ECRHS-Uppsala; <45 years), ≥45 years cohort within the V&V study, and the Rotterdam study (≥45 years). Blood eosinophils at baseline were classified as normal (<300 cells·μL⁻¹) or elevated (≥300 cells·μL⁻¹). Lung function was measured at baseline and follow-up with spirometry: forced expiratory volume in 1 s (FEV₁), vital capacity (VC) and their ratio FEV₁/VC. The association between blood eosinophils and lung function was tested cross-sectionally using linear regression and longitudinally using a mixed model, both adjusted for age, sex, height, pack-years smoking and smoking status. Stratified analyses were done for asthma.

Results

Elevated blood eosinophils were associated with lower FEV₁ (regression coefficient −147 mL (95% CI −188 to −105 mL)), VC (−120 mL (−165 to −75 mL)) and FEV₁/VC (−1.3% (−1.9% to −0.6%)) at baseline in the two <45 years cohorts, and with lower FEV₁ (−70 mL (−112 to −27 mL)) and FEV₁/VC (−1.8% (−2.6% to −1.0%)) in the two ≥45 years cohorts. Elevated blood eosinophils were associated with an accelerated decline in FEV₁ (−5.5 mL·year⁻¹ (95% CI −10.5 to −0.5 mL·year⁻¹)) and VC (−6.4 mL·year⁻¹ (−11.26 to −1.5 mL·year⁻¹)) compared to normal blood eosinophils in the younger asthmatic subjects in the longitudinal studies.

Conclusion

Elevated blood eosinophils are associated with lower lung function in the general population and with an accelerated lung function decline among asthmatic individuals.

Elevated blood eosinophils (≥300 cells per μL) associate with lower lung function in an adult general population and with a worse lung function trajectory in adult asthmatic individualshttps://bit.ly/3fJJ10h

Developments in the field of clinical allergy in 2018 through the eyes of Clinical and Experimental Allergy, Part II

In this article, we describe developments in the field of clinical allergy as described by Clinical and Experimental Allergy in 2018; epidemiology, asthma and rhinitis, clinical allergy and allergens are all covered.

Viral etiology and atopic characteristics in high-risk asthmatic children hospitalized for lower respiratory tract infection

BACKGROUND

Viral etiology and atopic characteristics, e.g., allergens and fractional exhaled nitric oxide (FeNO), play essential roles in asthma development. This study aimed to investigate associations among them in children at high risk of developing asthma to guide reliable diagnosis and treatment of wheezing.

METHODS

From April 2016 to August 2017, 135 children aged <3 years identified as being at high risk of asthma and hospitalized for lower respiratory tract infection (LRTI) with wheezing were recruited as research subjects (observation group). Real-time fluorescent polymerase chain reaction (PCR) was used to explore their etiology. Samples were also evaluated with Phadiatop (Pharmacia Diagnostics AB, Uppsala, Sweden). Additionally, 200 non-asthmatic, non-allergic, healthy children who were screened and followed up in the Echocardiography clinic during the study period were recruited as a healthy control group for FeNO measurement, and the observation group also underwent FeNO measurement.

RESULTS

Among the observation group, viruses were positively detected in 49.63%. The most often detected virus was human rhinovirus (HRV; 25.19%). Compared with children aged <12 months, those aged 1-3 years were more susceptible to HRV infection and had lower sensitivity rates for inhalant allergens and higher T-IgE. The virus-detected group had a higher sensitivity rate for inhalant allergens compared with the virus-undetected group. FeNO in the observation group was lower than that in the healthy control group. The second-wheezing group had higher sensitivity rates for dust mites and fungi and higher T-IgE levels compared with the first-wheezing group.

CONCLUSIONS

HRV was the most common viral pathogen present during an asthmatic attack in infants and young children at elevated risk of asthma. Allergy is a risk factor for both initial wheezing and repeated wheezing. Inhalant allergen-sensitive children are more susceptible than others to viral infection.

Clinical utility of fractional exhaled nitric oxide in severe asthma management

Asthma is a chronic inflammatory disease of the airways, affecting over 350 million people worldwide and placing a significant burden on healthcare providers and wider society. Approximately 5-10% of asthma patients are diagnosed with severe asthma and typically are associated with increased risk of hospitalisation from exacerbations, increased morbidity, mortality and higher asthma-associated healthcare costs. Nitric oxide (NO) is an important regulator of immune responses and is a product of inflammation in the airways that is over-produced in asthma. Fractional exhaled NO (F _eNO) is predominantly used as a predictor of response to inhaled corticosteroids (ICSs), to monitor adherence and as a diagnostic tool in ICS-naïve patients. In the UK, the National Institute for Health and Care Excellence (NICE) guidelines recommend the use of F _eNO for the initial diagnosis of patients with suspected asthma. In the USA, American Thoracic Society (ATS) guidelines recommend F _eNO as part of the initial diagnosis of asthma and for monitoring of airway inflammation. F _eNO has also been shown to be a predictive factor for asthma exacerbations, with higher levels being associated with a greater number of exacerbations. In addition, higher levels of F _eNO have been shown to be associated with a decline in lung function. F _eNO testing is a cost-effective procedure and has been shown to improve patient management when combined with standard assessment methods. Recent evidence suggests that F _eNO may also be useful as a surrogate biomarker for the assessment and management of severe asthma and to predict responsiveness to some biological therapies.

Comparison of fractional exhaled nitric oxide, spirometry, and Asthma Control Test, in predicting asthma exacerbations: A prospective cohort study

Context

Fractional exhaled nitric oxide (FeNO) is a noninvasive test for airway inflammation in asthma. The usefulness of FeNO in predicting exacerbations is uncertain.

Aims

The study aims to assess and compare the ability of FeNO, spirometry, and asthma control test (ACT) in predicting future exacerbations of asthma and their correlation with each other.

Settings and Design

This prospective, cohort study was conducted at the Department of Respiratory Medicine, Kasturba Medical College, Manipal.

Materials and Methods

Adult asthma patients of age 18-65 years were included. Patients with a smoking history of >10 pack-years and those in whom spirometry was contraindicated were excluded. Patients who consented underwent FeNO and spirometry. The control of asthma was assessed using the ACT questionnaire. We captured the number of exacerbations in the follow-up period of 4 months.

Statistical Analysis Used

Mann-Whitney test was used to compare the utility of FeNO, spirometry, ACT in predicting exacerbations and Spearman's correlation coefficient was used to ascertain the correlation among them.

Results

Of 154 study patients, 28% had exacerbations. We found that there was no significant difference in FeNO in patients with and without exacerbations. The median (interquartile range [IQR]) FEV1% in the patients with and without exacerbations were 68 (55-79) and 75 (65-88), respectively (P = 0.013). The median (IQR) ACT score in patients with exacerbations was 12 (10-16) which was significantly lower than in those without exacerbation in whom it was 16 (14-18) (P = 0.003). There was a negative correlation of ACT with FeNO (Correlation coefficient: -0.167, P = 0.038). The median (IQR) FeNO level (ppb) was lower in patients who were on inhaled corticosteroid (ICS) than in the other group values being 22 (14-38) and 30 (17-58), respectively (P = 0.05).

Conclusions

In our study, FEV1% and ACT score could predict exacerbations of asthma whereas FeNO could not. FeNO level correlated inversely with ACT score. FeNO level decreased with inhaled corticosteroid usage.

Development of an automated ImmunoCAP research assay for eosinophil derived neurotoxin and its use in asthma diagnosis in children

Background

Eosinophil Derived Neurotoxin (EDN) is an eosinophil granule protein that is released during eosinophil activation. EDN has proven to be a promising marker for eosinophilic inflammation both in asthma and in wheezing symptoms in children.

Objectives

Here we present a novel ImmunoCAP^TM automated immunofluorescence research assay for measurement of EDN and its potential use in diagnosis of asthmatic children.

Methods

We report the analytical performance of the assay in serum, heparin- and EDTA-plasma in terms of precision, linearity, sensitivity, interfering substances and specimen handling. We also compared the EDN research assay with established methods for asthma diagnosis: fraction of exhaled nitric oxide (FeNO) and blood eosinophil fraction (EOS%) to demonstrate the diagnostic value of EDN in childhood asthma.

Results

The total precision (measured using percentage CV) was ≤5.8% for both serum and plasma. The dilution analysis yielded linear results across the dynamic range of the assay for both serum and plasma. No notable interferences of endogenous substances were observed.

The median concentration of EDN was significantly higher in the asthma group compared to the healthy controls and the EDN correlates well with EOS%.

Conclusions

we have shown that EDN can be measured reliably and robustly with the ImmunoCAP platform in both serum and plasma samples. EDN can be used to distinguish asthmatic from healthy children and correlates well with EOS% and could be a valuable complement to both EOS% and FeNO.

Serum levels of IL-5, IL-6, IL-8, IL-13 and IL-17A in pre-defined groups of adult patients with moderate and severe bronchial asthma

BACKGROUND

Bronchial asthma (BA) is a complex disease characterised by persistent inflammation. Exhaled nitric oxide (FeNO) and blood eosinophil count (b-Eos) are biomarkers for type 2 endotype of BA.

OBJECTIVE

To analyse a panel of serum interleukins and total IgE in predefined by FeNO and b-Eos groups of moderate and severe BA patients.

METHODS

Serum levels of IL-5, IL-6, IL-8, IL-13 and IL-17A (ELISA) were measured in 30 healthy controls (HC) and 80 adult BA patients. BA patients were split into 4 groups. Group 1:Low FeNO/Low b-Eos (n = 23; 28.8%); Group 2:Low FeNO/High b-Eos (n = 17; 21.3%); Group 3:High FeNO/Low b-Eos (n = 15; 18.8%); Group 4:High FeNO/High b-Eos (n = 25; 31.3%).

RESULTS

All interleukins and total IgE were significantly higher in patients with BA as compared with HC. IL-5 levels were highest in Group 2 (p < 0.05). IL-6, IL-13 and IL-17A levels were elevated in Groups 2, 3 and 4 as compared with HC (p < 0.05). Higher IL-8 levels were associated with a pattern of current smokers. Highest IL-17A levels were found in type 2 high groups with frequent exacerbations, mostly uncontrolled and severe BA. We have found a distinct pattern for each group based on demographic, clinical, functional, immunological and inflammatory characteristics.

CONCLUSION

FeNO and b-Eos are useful in the identification of severe type 2 BA subgroups with frequent exacerbations. IL-5, IL-6, IL-13 and IL-17A are involved in the persistent type 2 immune response in moderate and severe BA. We have identified a pattern of refractory, severe type 2/IL-17A high BA in the real clinical practice.