Exhaled nitric oxide, total serum IgE and allergic sensitization in childhood asthma and allergic rhinitis

Exhaled Nitric Oxide as Biomarker of Type 2 Diseases

Nitric oxide (NO) is a short-lived gas molecule which has been studied for its role as a signaling molecule in the vasculature and later, in a broader view, as a cellular messenger in many other biological processes such as immunity and inflammation, cell survival, apoptosis, and aging. Fractional exhaled nitric oxide (FeNO) is a convenient, easy-to-obtain, and non-invasive method for assessing active, mainly Th2-driven, airway inflammation, which is sensitive to treatment with standard anti-inflammatory therapy. Consequently, FeNO serves as a valued tool to aid the diagnosis and monitoring of several asthma phenotypes. More recently, FeNO has been evaluated in several other respiratory and/or immunological conditions, including allergic rhinitis, chronic rhinosinusitis with/without nasal polyps, atopic dermatitis, eosinophilic esophagitis, and food allergy. In this review, we aim to provide an extensive overview of the current state of knowledge about FeNO as a biomarker in type 2 inflammation, outlining past and recent data on the application of its measurement in patients affected by a broad variety of atopic/allergic disorders.

Relationship between exhaled nitric oxide and biomarkers of atopy in children and adolescents with allergic rhinitis

INTRODUCTION

Measurement of the exhaled nitric oxide fraction (FeNO) has been proposed as an indirect and non-invasive method to detect eosinophilic airway inflammation. Allergic rhinitis (AR) is frequently associated with high levels of FeNO. Allergic sensitization can contribute to the recruitment of eosinophils in the airway and the consequent increase in FeNO.

OBJECTIVE

To correlate FeNO values with inflammatory and atopic sensitization biomarkers in patients with AR.

PATIENTS AND METHODS

Observational, analytical, cross-sectional study. Children and adolescents with AR without asthma were included. FeNO, blood eosinophil count, total serum IgE were determined and skin tests with aeroallergens were performed by calculating the scores for PPC1 (number of positive allergens), STS2 (sum of millimeters of positive papules) and the atopy index (ratio between STS2/STS1). Spearman's correlation test was used between FeNO and variables of inflammation and atopy.

RESULTS

Twenty-eight patients between 6 and 17 years old were included. There was a significant positive correlation between FeNO and blood eosinophils (r=.38; p=.047) and between FeNO and the atopy index (r=.40; p=.03). No correlation was found between FeNO and total serum IgE (r=.24; p=.21), STS1 (r=.20; p=.32) and STS2 (r=.34; p=.08).

CONCLUSION

In children and adolescents with AR, FeNO was correlated with the atopy index and the blood eosinophil count. These last biomarkers could be used as alternatives for FeNO as biomarkers of lower airway inflammation in patients with AR.

Association between environmental exposure to phthalates and allergic disorders in Korean children: Korean National Environmental Health Survey (KoNEHS) 2015-2017

BACKGROUND

Phthalates are common industrial chemicals that are used as plasticizers in plastics, personal care products, and building materials. Although these chemicals have been suspected as risk factors for allergic outcomes among children, inconsistent associations between environmental exposure to phthalates and allergic disorders have been found across different populations. Therefore, this study aimed to assess whether environmental phthalate exposure was associated with parent-reported current allergic symptoms (atopic dermatitis, AD; asthma; and allergic rhinitis, AR) and the index of allergic response (levels of serum total immunoglobulin E, IgE) in a nationally representative sample of children.

METHODS

In this study, children aged 3-17 years (n = 2208) were recruited from the Korean National Environmental Health Survey (KoNEHS) 2015-2017 to conduct an analysis of their current allergic symptoms. Among this number of children, the total IgE analysis included 806 participants because total IgE levels were only measured in children aged 12-17 years.

RESULTS

After adjusting for all covariates, mono-benzyl phthalate (MBzP) [OR (95% CI) = 1.15 (1.01, 1.30)], mono-(carboxyoctyl) phthalate (MCOP) [OR (95% CI) = 1.35 (1.02, 1.78)], and the sum of di-(2-ethylhexyl) phthalate metabolites (∑DEHP) [OR (95% CI) = 1.39 (1.09, 1.79)] were associated with increased odds of current AD. MCOP [OR (95% CI) = 1.19 (1.01, 1.40)], mono-(carboxynonyl) phthalate (MCNP) [OR (95% CI) = 1.24 (1.05, 1.45)], and ∑DEHP [OR (95% CI) = 1.22 (1.02, 1.44)] were also associated with increased odds of current AR. Individual DEHP metabolites showed similar associations with current AD and AR. In addition, MCNP was positively related to IgE levels [β (95% CI) = 0.26 (0.12, 0.40)]. MBzP [OR (95% CI) = 1.17 (1.01, 1.35)], MCOP [OR (95% CI) = 1.62 (1.12, 2.32)], and mono-(2-ethyl-5-oxohexyl) phthalate (MEOHP) [OR (95% CI) = 1.36 (1.06, 1.76)] showed positive relationships with allergic multimorbidity. Moreover, higher concentrations of MCNP were related to increased odds of experiencing both current AR and total IgE levels [OR (95% CI) = 1.98 (1.29, 3.04)], and children with elevated IgE levels (>100IU/mL) were more likely to have current AR associated with MCNP than those without elevated IgE levels (p = 0.007). Specifically, the relationship between MCNP and current AR was significantly mediated through alterations in IgE levels (14.7%), and MCNP also showed the positive association with current AR, independent of IgE (85.3%).

CONCLUSION

These results suggest that environmental exposure to phthalates may affect the immune system and increase the occurrence of allergic symptoms in children.

Vitamin D Levels in Asymptomatic Children and Adolescents with Atopy during the COVID-19 Era

This study assessed vitamin D status in asymptomatic children and adolescents in Greece, with and without atopy, and possible changes during the coronavirus disease 2019 (COVID-19) pandemic. Serum levels of 25-hydroxy-vitamin D (25(OH)D) and total immunoglobulin E (IgE), and eosinophil count were measured in 340 asymptomatic children and adolescents (155 males, 185 females), mean age 8.6 ± 4.6 years, recruited over a period of 24 months (February 2019–January 2021). Atopy, defined by high level of IgE for age, was associated with vitamin D deficient status (p = 0.041). Subjects with and without atopy showed similar rates of insufficient and normal levels of 25(OH)D. The median level of 25(OH)D was significantly higher in subjects recruited during the pandemic, when home confinement rules were observed, than before the pandemic, and significantly more children had normal levels of 25(OH)D (p < 0.001), but no differences were noticed for IgE levels or eosinophil count. These results support a link between vitamin D and allergic and infectious inflammations, and specifically the association of vitamin D deficiency with asymptomatic atopy, defined as increased IgE level for age.

Contributions of asthma, rhinitis and IgE to exhaled nitric oxide in adolescents

Exhaled nitric oxide fraction (F_eNO) is an indicator of allergic airway inflammation. However, it is unknown how asthma, allergic rhinitis (AR) and allergic sensitisation relate to F_eNO, particularly among adolescents and in overlapping conditions. We sought to determine the associations between asthma, AR, and aeroallergen immunoglobulin (Ig)E and F_eNO in adolescents.

We measured F_eNO among 929 adolescents (aged 11–16 years) in Project Viva, an unselected prebirth cohort in Massachusetts, USA. We defined asthma as ever asthma physician diagnosis plus wheezing in the past year or taking asthma medications in the past month, AR as a physician diagnosis of hay fever or AR, and aeroallergen IgE as any IgE >0.35 IU·mL⁻¹ among 592 participants who provided blood samples. We examined associations of asthma, AR and IgE with percent difference in F_eNO in linear regression models adjusted for sex, race/ethnicity, age and height, maternal education and smoking during pregnancy, and household/neighbourhood demographics.

Asthma (14%) was associated with 97% higher F_eNO (95% CI 70–128%), AR (21%) with 45% higher F_eNO (95% CI 28–65%), and aeroallergen IgE (58%) with 102% higher F_eNO (95% CI 80–126%) compared to those without each condition, respectively. In the absence of asthma or AR, aeroallergen IgE was associated with 75% higher F_eNO (95% CI 52–101), while asthma and AR were not associated with F_eNO in the absence of IgE.

The link between asthma and AR with F_eNO is limited to those with IgE-mediated phenotypes. F_eNO may be elevated in those with allergic sensitisation alone, even in the absence of asthma or AR.

While asthma, allergic rhinitis (AR) and allergic sensitisation are associated with higher F_ENO, asthma and AR in the absence of aeroallergen IgE are not associated with F_ENO. When elevated in asthma or AR, F_ENO suggests allergic sensitisation.https://bit.ly/3bGgr0r

Change in exhaled nitric oxide during peanut challenge is related to severity of reaction

BACKGROUND

Peanut allergy affects 3% of Australian children and has a higher risk of anaphylaxis than most food allergies. Predicting who is likely to develop anaphylaxis is still an inexact science. The fraction of exhaled nitric oxide (FeNO) shows promise as a biomarker involved in peanut allergy, as nitric oxide plays a role in inhibiting mast cell degranulation which is relevant in anaphylaxis, where mast cell degranulation plays a mediator role. The aim of this study was to assess the change in FeNO in children during peanut challenge.

METHODS

Thirty-six children aged from 5 to 17 years were recruited for open-labelled peanut challenge. Participants had skin prick test to peanut performed, and serum collected for Ara h2 specific IgE and peanut specific IgE. FeNO was measured by portable device (NIOX VERO) prior to and throughout the peanut challenge.

RESULTS

When grouped according to reaction type at peanut challenge (anaphylaxis, clinical allergy not anaphylaxis and tolerant), there were significant differences in the mean change in FeNO measurement between the anaphylaxis group and the clinical allergy, not anaphylaxis group (p = 0.005), and between the anaphylaxis group and tolerant group (p < 0.0001).

CONCLUSIONS

FeNO decreased more significantly in those who subsequently developed anaphylaxis than in those with clinical allergy, not anaphylaxis or negative peanut challenge (tolerance). As a bedside test that can be used in children, it has potential for further research into mechanisms of anaphylaxis in food allergy and potentially assists in predicting an imminent anaphylactic reaction in some patients.Trial registration ClinicalTrials.gov: PEAnut Anaphylaxis Predictors (PEAAP) NCT02424136.

The Pattern of Sensitization Influences Exhaled and Nasal Nitric Oxide Levels in Young Adults

Nitric oxide (NO) from upper (nasal NO, nNO) or lower airways (fractional exhaled NO, FeNO) is considered a surrogate marker for Th2-type inflammation, which is influenced by atopy. The aim of this study was to analyze nNO and FeNO in regard to qualitative and quantitative aspects of sensitization. We evaluated 244 non-smoking young adults. All of them were first-year students recruited for a longitudinal study. An inhalation allergy screening tool was used for atopy definition (specific immunoglobulin E (sIgE) to sx1 ≥ 0.35 kU/L), and also sIgE response to three inhalant perennial allergens, house dust mite (HDM, d1), cat (e1), and dog (e5), was determined in the non-pollen season. With respect to sx1, 100 subjects could be classified as atopic. Sensitization to one, two, or three perennial allergens could be demonstrated in 46, 10, and 16 students, respectively. The subjects with positive IgE response to sx1, but not sensitized to HDM, cat, and/or dog, had FeNO levels comparable to those of non-atopic subjects (13.5 vs. 13.0 ppb, respectively; p = 0.485). These levels were significantly lower compared to atopic subjects being sensitized to any perennial allergen (19.0 ppb; p = 0.0003). After grouping the atopic subjects for perennial sensitization patterns, significantly higher FeNO could be detected in subjects with poly-sensitization (n = 26; 26.0 ppb) compared to the mono-sensitized ones (n = 46; 18.0 ppb; p = 0.023). Regarding nNO, no differences could be observed. Applying a two-way ANOVA, we could reveal a significant correlation of specific HDM-IgE CAP-class with FeNO (p < 0.0001) and nNO levels (p = 0.007). Finally, a significant relationship was found between nNO and FeNO for the whole cohort (p < 0.0001). In summary, our findings support the argument that atopy and perennial sensitization should be considered for the interpretation of NO.

Association of pediatric obesity and asthma, pulmonary physiology, metabolic dysregulation, and atopy; and the role of weight management

Introduction: Obesity affects about 40% of US adults and 18% of children. Its impact on the pulmonary system is best described for asthma. Areas covered: We reviewed the literature on PubMed and Google Scholar databases and summarize the effect of obesity, its associated metabolic dysregulation and altered systemic immune responses, and that of weight gain and loss on pulmonary mechanics, asthma inception, and disease burden. We include a distinct approach for diagnosing and managing the disease, including pulmonary function deficits inherent to obesity-related asthma, in light of its poor response to current asthma medications. Expert opinion: Given the projected increase in obesity, obesity-related asthma needs to be addressed now. Research on the contribution of metabolic abnormalities and systemic immune responses, intricately linked with truncal adiposity, and that of lack of atopy, to asthma disease burden, and pulmonary function deficits among obese children is fairly consistent. Since current asthma medications are more effective for atopic asthma, investigation for atopy will guide management by distinguishing asthma responsive to current medications from the non-responsive disease. Future research is needed to elucidate mechanisms by which obesity-mediated metabolic abnormalities and immune responses cause medication non-responsive asthma, which will inform repurposing of medications and drug discovery.

FCER2 T2206C variant associated with FENO levels in asthmatic children using inhaled corticosteroids: The PACMAN study

BACKGROUND

The FCER2 gene, via encoding of the CD23 receptor, plays an important role in the regulation of IgE responses. A genetic variant of the FCER2 gene (T2206C) was previously shown to be associated with IgE levels in asthmatic children. IgE sensitization has also been linked to increased levels of fractional exhaled nitric oxide (FENO).

OBJECTIVE

To investigate whether the FCER2 T2206C variant influences FENO levels in asthmatic children with a reported use of inhaled corticosteroids (ICS).

METHODS

This cross-sectional study involved 593 asthmatic children with a reported use of ICS, availability of FENO measurements and genotyping data on the FCER2 T2206C variant (rs28364072). An additive genetic model was assumed, and the association between the FCER2 T2206C variant and the log-transformed (ln) FENO levels was evaluated using linear regression analysis, adjusted for age, sex, adapted British Thoracic Society (BTS) treatment steps and atopy.

RESULTS

The mean age of the population was 9.1 ± 2.2 years, and the median of FENO levels was 13.0 ppb with an interquartile range (IQR) of (8.0-27.5 ppb). The minor allele (G) frequency of rs28364072 was 29.6%, and each extra copy of the G allele was significantly associated with a lower level of the geometric mean of FENO (log scale, β = -0.12, 95% CI: -0.23, -0.02).

CONCLUSION AND CLINICAL RELEVANCE

Our results showed that the FCER2 T2206C variant was significantly associated with lower FENO levels in carriers of the G allele. Nevertheless, this SNP contributed little to the variability in FENO levels in this patient population. Our findings contribute to the present knowledge on FENO in asthmatic children; however, future replication studies are required to establish the role of this gene in relation to FENO.

Fractional Exhaled Nitric Oxide Values in Indigenous Australians 3 to 16 Years of Age

BACKGROUND

Fractional exhaled nitric oxide (Feno) levels can identify eosinophilic asthma phenotypes. We aimed to determine Feno values of healthy Aboriginal and/or Torres Strait Islander (Indigenous) Australians, differences between these Indigenous ethnic groups, and appropriateness of published cutoff values.

METHODS

We measured Feno levels in 1,036 Indigenous Australians (3-16 years of age). Participants were classified into healthy (ie, no asthma or atopy history) or asthmatic and/or atopic groups.

RESULTS

Median Feno values and distribution did not differ between Indigenous ethnicities. For healthy participants < 12 years of age (n = 390), 7.2% of our cohort fell into the inflammatory zone of the American Thoracic Society (ATS), National Institute for Health and Care Excellence (NICE), and British Thoracic Society (BTS)/Scottish Intercollegiate Guidelines Network (SIGN) guidelines (cutoff 35 parts per billion [ppb]), but only 3.8% fell into this category when using the Global Initiative for Asthma (GINA) guidelines (50 ppb). Similarly, when using the NICE and BTS/SIGN guidelines (40 ppb) for participants 12 to 16 years of age (n = 213), more healthy participants fell into the inflammatory zone compared with the ATS and GINA guidelines (50 ppb) (9.9% vs 4.7%, respectively).

CONCLUSIONS

Feno values for healthy Indigenous Australians children (3-16 years of age) are likely higher than published white-based values. The GINA recommended cutoff value (> 50 ppb) appears the most appropriate for identifying healthy Indigenous children but requires confirmation from a larger study.

Values of fractional exhaled nitric oxide for cough-variant asthma in children with chronic cough

BACKGROUND

Chronic cough is a common symptom in children. We wished to explore the value of fractional exhaled nitric oxide (FeNO) for cough-variant asthma (CVA) in children with chronic cough.

METHODS

This prospective cohort study was conducted in the Children's Hospital of Soochow University from January 2012 to December 2014. Children aged 6-14 years with a cough of duration >4 weeks were enrolled. They underwent FeNO measurement, sputum cytology and pulmonary function tests.

RESULTS

A total of 115 patients and 25 healthy controls were evaluated. For the diagnosis of CVA, the optimal FeNO cutoff value was 25 ppb with a sensitivity of 84.0%, specificity of 97.1%, positive predictive value of 97.5%, and negative predictive of being 81.4%. The FeNO level had a significant correlation with eosinophil count in sputum (P<0.05). FeNO level in CVA was decreased significantly after treatment (P=0.001).

CONCLUSIONS

In children, FeNO measurement might be an excellent method for diagnosing CVA with high sensitivity and specificity.

FeNO and Exercise Testing in Children at Risk of Asthma

BACKGROUND

Exercise testing is the gold standard for diagnosing exercise-induced bronchoconstriction in children, but requires considerable cooperation and medical resources. Therefore, fraction of exhaled nitric oxide (FeNO) has been proposed as a tool to predict the need for exercise testing.

OBJECTIVE

The objective of this study was to investigate the relationship between FeNO, exercise test results, and a history of respiratory symptoms during exercise in children at risk of asthma.

METHODS

FeNO measurement, exercise testing, and interview about respiratory symptoms during exercise were completed in 224 seven-year-old children from the at-risk Copenhagen Prospective Studies on Asthma in Childhood₂₀₀₀ birth cohort. The associations between FeNO, exercise test results, and reported respiratory symptoms during exercise were analyzed adjusting for gender, respiratory infections, and inhaled corticosteroid treatment. The associations were also analyzed stratified by asthma and atopic status.

RESULTS

Of the 224 children, 28 (13%) had an established asthma diagnosis and 58 (26%) had a positive exercise test (≥15% drop in forced expiratory volume in 1 second [FEV₁] from baseline). FeNO and bronchial obstruction after exercise were linearly associated with a doubling of FeNO corresponding to a 2.4% drop in FEV₁ (95% confidence interval, 0.8-4.1; P < .01). However, a receiver operating characteristic curve analysis showed that the best cutoff of FeNO for predicting exercise test outcome among children who reported respiratory symptoms during exercise was 17 ppb, which only had 74% negative predictive value. There was no association between FeNO and reported respiratory symptoms during exercise (odds ratio = 1.3 [0.8-1.9]; P = .29) or reported symptoms during exercise and exercise test results (odds ratio = 1.0 [1.0-1.1]; P = .12).

CONCLUSIONS

A history of respiratory symptoms during exercise was not associated with either elevated FeNO or a positive exercise test in children at risk of asthma. FeNO and exercise test results were linearly associated traits, but FeNO could not reliably be used dichotomized to predict the need of exercise testing.

The Emerging Role of The Eosinophil and Its Measurement in Chronic Cough

Although the aetiology of chronic cough in guidelines is clearly stated as asthma and related syndromes, gastro-oesophageal reflux disease (GORD), and upper airways disease, the inflammatory mechanisms underlying these conditions differ. Recent studies on asthma have increasingly focused on its molecular phenotypes instead of clinical characteristics. Here, we proposed the hypothesis that divides cough into two groups; the eosinophilic and neutrophilic. This division will enhance our ability to recognise the type of airway inflammation which, as a consequence will lead us to more targeted and personalized treatment approaches.

A Randomized Controlled Trial of the Effect of Broccoli Sprouts on Antioxidant Gene Expression and Airway Inflammation in Asthmatics

BACKGROUND

Broccoli sprouts (BS) are the richest source of sulforaphane (SFN), which is a potent inducer of phase II enzymes, which play a critical role in preventing oxidative stress (OS) and inflammation.

OBJECTIVES

The objective of this study was to determine if ingestion of whole BS improves airway inflammatory and physiologic outcomes, and OS in adults with asthma and allergic sensitization to an indoor allergen.

METHODS

The study is a double-blind, placebo-controlled, randomized trial to compare the effects of BS with placebo (alfalfa sprouts [AS]) on airway inflammation and markers of OS. Forty adults (aged 18-50 years) were randomized to eat either (a) 100 g of BS daily or (b) 100 g of AS daily for 3 days. Fractional exhaled nitric oxide (FENO), forced expiratory volume 1, nasal epithelial and PBMC gene expression, inflammatory and OS biomarkers, and symptoms were assessed both before and after ingestion of the sprouts. The primary outcome variable was the change in FENO. Secondary outcome measures included rhinitis and asthma symptoms, lung function, and OS and inflammatory biomarkers.

RESULTS

BS ingestion for 3 consecutive days did not reduce FENO, despite resulting in a marked increase in serum SFN concentrations (21 vs 22 parts per billion, P = .76). Furthermore, BS consumption did not induce cytoprotective antioxidant genes in either PBMCs or nasal epithelial cells, reduce OS and inflammatory markers, or improve lung function.

CONCLUSIONS

Ingestion of whole BS for 3 days does not appear to improve eosinophilic pulmonary inflammation, inflammatory and OS biomarkers, or clinical features of asthma among atopic adults with asthma despite resulting in a marked increase in serum SFN levels.

Setting reference values for exhaled nitric oxide: a systematic review

BACKGROUND

The values obtained when the fraction of exhaled nitric oxide (FeNO) is measured are affected by several factors that are specific to the individual patient, making interpretation difficult, especially in the initial assessment of patients with respiratory symptoms.

METHODS

Systematic review of studies on FeNO reference values and individual-specific factors that influence them.

RESULTS

From 3739 references, 15 studies were included. Four studies included children and adolescents. In nine studies, samples were selected from the general population. Most studies reported objective measures for atopy (nine studies), but not for smoking status (one). Significant determinants of FeNO values reported were age and height (seven studies), atopy (six), smoking (four), weight (four), sex (three) and race (three). Additional factors were included in eight studies. R2 was reported in only five studies. The logarithmic transformation of FeNO was inadequately described in seven studies.

CONCLUSION

There are several equations for FeNO reference values that may be used in clinical practice, although the factors they include and the statistical methods they use vary considerably. We recommend the development of standard methods for the evaluation of normal FeNO data and that reference equations should be formulated based on a predetermined physiological model.

Lower airway inflammation and hyperresponsiveness in non-asthmatic patients with non-allergic rhinitis

BACKGROUND

Potential associations between non-allergic rhinitis (NAR) and asthma have been verified epidemiologically, but these associations remain not very clear. It is necessary to further explore the possible implication of lower airway abnormities in NAR patients but without asthma. This study aims to determine lower airway hyperresponsiveness (AHR), inflammation and lung function in non-asthmatic patients with NAR.

METHODS

We recruited 262 non-asthmatic patients with NAR, 377 with AR and 264 healthy subjects. All subjects were non-smokers who underwent meticulous history taking, nasal examination, allergen skin prick test (SPT), blood routine test, measurement of fractional exhaled nitric oxide (FeNO), methacholine bronchial challenge test and induced sputum eosinophil count, in this order.

RESULTS

Compared with healthy subjects, non-asthmatic patients with NAR yielded markedly lower FEV1/FVC, maximal mid-expiratory flow (MMEF), mid-expiratory flow when 50% of FVC has been expired (MEF50%) and mid-expiratory flow when 75% of FVC has been expired (MEF25%) (P<0.05). Differences in spirometry between group AR and NAR were unremarkable (P>0.05). Patients with NAR yielded higher rate of AHR and higher FeNO levels than healthy subjects but lower than those with AR. The proportion of lower airways disorders (sputum eosinophilia, high FeNO levels or AHR) was highest in group AR (70.8%), followed by NAR (53.4%) and healthy subjects (24.2%) (P<0.01). However, sputum eosinophils in NAR patients were not higher compared with healthy subjects (P>0.05). Sputum eosinophils and FeNO had significant correlation with positive AHR and MMEF in group AR but not in NAR.

CONCLUSIONS

Non-asthmatic patients with NAR harbor lower AHR, small airways dysfunction and inflammation, despite being less significant than those with AR. This offers clues to unravel the link between NAR and asthma.

Airway hyper-responsiveness to mannitol provides a good evaluation of atopy in childhood asthma

AIM

The relationship between airway hyper-responsiveness (AHR) and atopy has been previously investigated, but there are still some issues to be clarified. The aim of this study was to assess the link between AHR and mannitol and atopy in asthmatic children.

METHODS

We evaluated 44 children with asthma, aged 6-16 years of age, using skin prick tests (SPTs), serum total and specific immunoglobulin E (IgE) levels and the mannitol challenge test (MCT).

RESULTS

We found a good correlation between AHR to mannitol and specific IgE against Dermatophagoides pteronissinus (r = -0.66, p < 0.001) and a weak correlation with specific IgE against dog dander (r = -0.33, p = 0.01) and Aspergillus fumigatus (r = -0.23, p = 0.02). Furthermore, we found a weak correlation between AHR to mannitol and serum total IgE (r = -0.30; p = 0.03), the sum of specific IgE to aeroallergens (r = -0.37, p = 0.01) and the number of positive SPTs (r = -0.31, p = 0.02).

CONCLUSION

Measuring AHR with MCT might provide an accurate evaluation of the degree of atopy in children. The patients with a higher degree of atopy were significantly more reactive to mannitol. In clinical practice, these results indicate that children with asthma who are more atopic may require more intensive treatment strategies to reduce AHR.

Establishing IMMULITE® 2000 cut-off values for serum allergen-specific immunoglobulin and exploring their relationship to exhaled nitric oxide

Aim

Paediatric cut-off values for serum allergen-specific IgE (sIgE) using the Siemens IMMULITE® 2000 system to diagnose allergic rhinoconjunctivitis have not been established. We aimed to determine cut-off levels for sIgE for 10 common inhalant allergens and to study the relationship between sIgE, total IgE and fractional exhaled nitric oxide (FE_NO).

Methods

We enrolled 243 schoolchildren, including 164 with allergic rhinoconjunctivitis. Parental interviews, skin prick tests, sIgE, total IgE, FE_NO measurements, spirometry and exercise tests were performed.

Results

Cut-off values with the best combined sensitivity and specificity were above the detection limit of the assay for seven of the ten allergens (0.23–1.1 kU/L). The overall accuracy of the IMMULITE® in detecting allergic rhinoconjunctivitis was good. sIgE was superior to total IgE and FE_NO in predicting allergic rhinoconjunctivitis to timothy, birch, mugwort, cat, dog and house dust mite. FE_NO was elevated in children with allergic rhinoconjunctivitis, irrespective of asthma.

Conclusion

Cut-off values for sIgE were dependent on the allergic phenotype and were above the IMMULITE® detection limit for seven of ten inhalant allergens. Consequently, using the detection limit for sIgE as the decision point would result in over-diagnosing allergic rhinoconjunctivitis. When measuring elevated FE_NO in children, allergic rhinoconjunctivitis should be suspected.

Exhaled nitric oxide measures allergy not symptoms in children with allergic rhinitis in primary care: a prospective cross-sectional and longitudinal cohort study

Background:

Allergic rhinitis (AR) and asthma are both inflammatory diseases and are often associated. Relationships between fractional exhaled nitric oxide (FeNO) and asthma, atopy, and quality of life have been shown.

Aims:

This study aimed to determine whether FeNO in children with AR (n=158) or combined AR and asthma (n=93) was associated with clinical symptoms, house dust mite (HDM)-specific IgE, and rhinitis-specific quality of life, both cross-sectionally and longitudinally.

Methods:

Children with AR aged 6–18 years (n=251) in primary care were assessed for FeNO, nasal symptom scores, asthma symptom scores, quality of life, and HDM-specific IgE at baseline and 2 years later.

Results:

We found similarly elevated FeNO in children with only AR and in those with combined AR and asthma. No correlations were found between FeNO and nasal or asthma symptoms and rhinitis-related quality of life. Longitudinal correlations were strongest for HDM-specific IgE (r=0.91, p<0.0001).

Conclusions:

FeNO was similar in a selected group of children with AR with and without asthma in primary care and was unrelated to symptoms or quality of life in both groups. FeNO is unlikely to be a useful biomarker of the clinical severity of upper or lower airway disease in primary care.

Fractional exhaled nitric oxide and impulse oscillometry in children with allergic rhinitis

Purpose

Airway inflammation, bronchial hyper-responsiveness (BHR), and bronchodilator response (BDR) are representative characteristics of asthma. Because allergic rhinitis (AR) is a risk factor for asthma development, we evaluated these 3 characteristics in AR using measurement of fractional exhaled nitric oxide (FeNO), a methacholine challenge test (MCT), and impulse oscillometry (IOS).

Methods

This study included 112 children with asthma (asthma group), 196 children with AR (AR group), and 32 control subjects (control group). We compared pulmonary function parameters and FeNO levels among the 3 groups. The AR group was subdivided into 2 categories: the AR group with BHR and the AR group without, and again pulmonary function and FeNO levels were compared between the 2 subgroups.

Results

FeNO levels were more increased in the AR and asthma groups than in the control group; within the AR group, FeNO was higher in the AR group with BHR than in the AR group without. The BDR was more increased in the AR group than in the control group when percent changes in reactance at 5 Hz (Δ X5) and reactance area (Δ AX) were compared. In the AR group, however, there was no difference in Δ X5 and Δ AX between the AR group with BHR and the AR group without.

Conclusions

Reversible airway obstruction on IOS and elevated FeNO levels were observed in children with AR. Because elevated FeNO levels can indicate airway inflammation and because chronic inflammation may lead to BHR, FeNO levels may be associated with BHR in AR. IOS can be a useful tool for detecting lower airway involvement of AR independent of BHR assessed in the MCT.

Relationship between atopy and bronchial hyperresponsiveness

Both atopy and bronchial hyperresponsiveness (BHR) are characteristic features of asthma. They are also found among non-asthmatic subjects, including allergic rhinitis patients and the general population. Atopy and BHR in asthma are closely related. Atopy induces airway inflammation as an IgE response to a specific allergen, which causes or amplifies BHR. Moreover, significant evidence of the close relationship between atopy and BHR has been found in non-asthmatic subjects. In this article, we discuss the relationship between atopy and BHR in the general population, asthmatic subjects, and those with allergic rhinitis. This should widen our understanding of the pathophysiology of atopy and BHR.

The relationship of plasma aluminum to oxidant-antioxidant and inflammation status in asthma patients

Aluminum (Al) is a non-essential mineral which human beings are exposed to on day-to-day life. The purpose of this study was to assess the concentrations of plasma Al and the relationship of those levels with risk factors for asthma. In total, 27 allergic asthmatics and 30 healthy volunteers were enrolled. Plasma Al and selected blood parameters were measured, and a pulmonary function test was performed. Higher Al concentrations were found in the asthmatics than the healthy controls. Increased immunoglobulin E, high-sensitivity C-reactive protein, lipid peroxidation products, and pro-inflammatory cytokines (tumor necrosis factor-α and interleukin [IL]-4) were observed, but IL-10 and overall antioxidant and enzyme activities were lower. Associations between oxidative-antioxidant status and inflammatory markers with plasma Al levels in asthmatics were noted. Al status was also linked to cytokine concentrations and pulmonary function. In conclusion, abnormal Al distribution may further precipitate oxidative stress and inflammation, alter Th1/Th2 lymphocyte balance, and therefore contribute to the development of asthma.

Effectiveness of Ischia thermal water nasal aerosol in children with seasonal allergic rhinitis: a randomized and controlled study

Allergic rhinitis is characterized by local inflammation. Nasal lavage may be a useful treatment, however, there are few studies on this topic. This study aims to evaluate the effects of Ischia thermal water nasal irrigation on allergic rhinitis symptoms and airway inflammation during the period of natural exposure to Parietaria pollen in children with allergic rhinitis and intermittent asthma. Forty allergic children were randomly divided into two groups: the first group (Group 1) practiced crenotherapy with thermal water aerosol for 15 days per month, for three consecutive months, the control group (Group 2) was treated with 0.9&#x0025; NaCl (isotonic) solution. In addition, all children were treated with cetirizine (0.5 gtt./kg/day once daily). Nasal symptom assessment, including Total Symptom Score (TSS), spirometry, and exhaled nitric oxide (FeNO) were considered before the treatment (T0), at the end of the treatment (T1) and again 2 weeks after the end of the treatment (T2). The study was registered in the Clinical Trials.gov (NCT01326247). Thermal water significantly reduced both TSS and FeNO levels and there was a significant relationship between reduction of nasal symptoms and FeNO values at the end of treatment with thermal water. In conclusion, this study shows that nasal crenotherapy with the hypermineral chloride-sodium water of Ischia was effective in children with seasonal allergic rhinitis based on the sensitivity to Parietaria. These results demonstrate that this natural treatment may be effective in a common and debilitating disease such as the allergic rhinitis.

Fractional exhaled nitric oxide measurements in rhinitis and asthma in children

Exaled nitric oxide (FeNO) is considered a good noninvasive marker to assess airway inflammation in asthma and allergic rhinitis. In asthma, exhaled NO is very useful to verify adherence to therapy, and to predict upcoming asthma exacerbations. It has been also proposed that adjusting anti-inflammatory drugs guided by the monitoring of exhaled NO, could improve overall asthma control. Other studies showed increased FeNO levels in subjects with allergic rhinitis.

Effects of atopy and rhinitis on exhaled nitric oxide values - a systematic review

Background

Atopy and rhinitis are among the factors affecting exhaled nitric oxide (FeNO) values and may contribute to difficulties in the clinical interpretation of FeNO measurements. However, data assessing their effects on FeNO values had never been summarized. This review aims to evaluate the effect of atopy and rhinitis in FeNO values in otherwise healthy individuals.

Methods

A systematic review was performed in Pubmed, Scopus and ISI Web of Knowledge. A two-step selection process was completed, and from 2357 references 19 were included. The inclusion criteria were: participants without known diseases other than rhinitis; atopy assessement by SPT or Specific IgE; and FeNO measurements according to ATS/ERS recommendations.

Results

The 8 articles measuring FeNO in children showed higher values in both allergic rhinitis and atopic children when compared with healthy children. The 11 articles performed in adults observed higher FeNO in AR patients comparatively with either healthy or atopic individuals. However, adult healthy and atopic individuals had similar FeNO values.

Conclusions

FeNO values are higher in individuals with rhinitis and/or atopy without other health problems. These effects are small, seem to be independent and should be further studied using multivariate models. The effect of atopy was observed only in children. The combined effect of atopy and rhinitis produced higher FeNO values in adults. These results support that both atopy and rhinitis should be considered when interpreting or when defining FeNO reference values.

Allergen exposure modifies the relation of sensitization to fraction of exhaled nitric oxide levels in children at risk for allergy and asthma

BACKGROUND

Studies on airway inflammation, measured as fraction of exhaled nitric oxide (FENO), have focused on its relation to control of asthma, but the contribution of allergen exposure to the increase in FENO levels is unknown.

OBJECTIVE

We evaluated (1) whether FENO levels were increased in children with allergic sensitization or asthma; (2) whether specific allergen exposure increased FENO levels in sensitized, but not unsensitized, children; and (3) whether sedentary behavior increased FENO levels independent of allergen exposures.

METHODS

At age 12 years, in a birth cohort of children with a parental history of allergy or asthma, we measured bed dust allergen (dust mite, cat, and cockroach) by means of ELISA, specific allergic sensitization primarily based on specific IgE levels, and respiratory disease (current asthma, rhinitis, and wheeze) and hours of television viewing/video game playing by means of questionnaire. Children performed spirometric maneuvers before and after bronchodilator responses and had FENO levels measured by using electrochemical detection methods (NIOX MINO).

RESULTS

FENO levels were increased in children with current asthma (32.2 ppb), wheeze (27.0 ppb), or rhinitis (23.2 ppb) compared with subjects without these respective symptoms/diagnoses (16.4-16.6 ppb, P < .005 for all comparisons). Allergic sensitization to indoor allergens (cat, dog, and dust mite) predicted higher FENO levels and explained one third of the variability in FENO levels. FENO levels were highest in children both sensitized and exposed to dust mite. Greater than 10 hours of weekday television viewing was associated with a 0.64-log increase in FENO levels after controlling for indoor allergen exposure, body mass index, and allergic sensitization.

CONCLUSION

Allergen exposures and sedentary behavior (television viewing/video game playing) might increase airway inflammation, which was measured as the FENO.

Methacholine and adenosine 5'-monophosphate (AMP) responsiveness, and the presence and degree of atopy in children with asthma

The relationship between atopy and bronchial hyperresponsiveness (BHR), both key features of asthma, remains to be clarified. BHR is commonly evaluated by bronchial challenges using direct and indirect stimuli. The aim of this study was to investigate the degree of BHR to methacholine (direct stimulus) and adenosine 5'-monophosphate (AMP) (indirect stimulus) according to the presence and degree of atopy in children with asthma. We performed a retrospective analysis of data from 120 children presenting with a diagnosis of asthma. These children were characterized by skin-prick tests (SPTs), spirometry and bronchial challenges with methacholine and AMP. Atopy was defined by at least one positive reaction to SPTs, and its degree was measured using serum total IgE levels, number of positive SPTs and atopic scores (sum of graded wheal size). A provocative concentration causing a 20% decline in FEV(1) (PC(20) ) was determined for each challenge. Patients with atopy(n=94) had a significantly lower AMP PC(20) than non-atopic patients (n=26), whereas methacholine PC(20) was not different between the two groups. Among the patients with atopy, there was no association between methacholine PC(20) and any atopy parameter. In contrast, a significant association was found between AMP PC(20) and the degree of atopy reflected in serum total IgE, number of positive SPTs and atopic scores (anova trend test, p=0.002, 0.001, 0.003, respectively). AMP responsiveness was associated with the presence and degree of atopy, whereas such a relationship was not observed for methacholine responsiveness. These findings suggest that atopic status may be better reflected by bronchial responsiveness assessed by AMP than by methacholine.

Bronchial hyperresponsiveness to methacholine and adenosine monophosphate and the degree of atopy in children with allergic rhinitis

BACKGROUND

nonasthmatic patients with allergic rhinitis often have bronchial hyperresponsiveness (BHR). Not only the presence but also the degree of atopy are important factors in BHR of patients with asthma. BHR is commonly evaluated by bronchial challenges using direct or indirect stimuli.

OBJECTIVES

to assess BHR to methacholine (direct) and to adenosine monophosphate (AMP) (indirect) in children with allergic rhinitis and to compare their relationships with the degree of atopy.

METHODS

methacholine and AMP challenges were performed in 88 children with allergic rhinitis, and a provocative concentration causing a 20% decrease in forced expiratory volume in 1 second (PC(20)) was calculated for each challenge. The degree of atopy was measured using serum total IgE levels, number of positive skin prick test results, and atopic scores (sum of graded wheal size).

RESULTS

BHR to methacholine (PC(20) <8 mg/mL) and to AMP (PC(20) <200 mg/mL) was observed in 22 (25%) and 30 (34%) patients, respectively. No association was found between BHR to methacholine and any atopy parameter. In contrast, serum total IgE levels and atopic scores were higher in the group with BHR to AMP than in the group without BHR to AMP. Furthermore, a significant association was found between the degree of these 2 parameters and BHR to AMP (score for trend, P < .001 and P = .03, respectively).

CONCLUSIONS

both BHR to methacholine and BHR to AMP were detected in a significant proportion of children with allergic rhinitis. The degree of atopy seems to be an important factor in BHR to AMP but not in BHR to methacholine.

Bronchial hyperresponsiveness to methacholine and adenosine 5'-monophosphate, and the presence and degree of atopy in young children with asthma

BACKGROUND

Bronchial hyperresponsiveness (BHR) is a characteristic feature of asthma, and is usually measured by bronchial challenges using direct or indirect stimuli. The relationship between atopy and BHR remains to be clarified, particularly in a population selected for asthma. Furthermore, data for young children are limited, although asthma frequently occurs in early childhood.

OBJECTIVE

The aim of this study was to investigate methacholine (direct stimulus) and adenosine 5'-monophosphate (AMP) (indirect stimulus) responsiveness according to the presence and degree of atopy in young children with asthma.

METHODS

A retrospective analysis of data from 122 preschool children (median age [range]: 5.3 years [4.0-6.8]) presenting with the diagnosis of asthma was performed. These children were characterized by skin-prick tests (SPTs) and bronchial challenges with methacholine and AMP, using a modified auscultation method. The end-point concentration, resulting in audible wheezing and/or oxygen desaturation, was determined for each challenge. Atopy was defined by at least one positive reaction to SPTs, and its degree was assessed using serum total IgE levels, number of positive SPTs, and atopic scores (sum of graded weal size).

RESULTS

Atopic patients (n=97) had a significantly lower AMP end-point concentration than non-atopic patients (n=25), whereas the methacholine end-point concentration was not different between the two groups. Among the atopic patients, there was no association between the methacholine end-point concentration and any of the atopy parameters. By contrast, a significant association was found between the AMP end-point concentration and the degree of atopy reflected in serum total IgE and atopic scores (χ² test for trend, P=0.001, 0.003, respectively).

CONCLUSION AND CLINICAL RELEVANCE

Young children with atopic asthma had a significantly greater AMP responsiveness than those with non-atopic asthma, whereas methacholine responsiveness was not significantly different between the two groups. The degree of atopy appeared to be an important factor in AMP responsiveness, but not in methacholine responsiveness, and thus might be a marker of airway inflammation in asthma.

The CC16 A38G polymorphism is associated with the development of asthma in children with allergic rhinitis

BACKGROUND

Although asthma and allergic rhinitis (AR) are considered to be one syndrome, many questions remain unanswered. Why do some AR patients develop asthma but others do not, and which factors play a role in the development of asthma that have so far not been clearly elucidated.

OBJECTIVE

We hypothesize that children with AR who have the Clara cell secretory protein (CC16, secretoglobin 1A1) 38A/38A genotype (rs3741240) have an increased likelihood of developing asthma.

METHODS

The study sample included 117 children, with AR, but no asthma diagnosed within the following 5 years, as the control group. Cases group (n=202) included age- and gender-matched children with AR first, and asthma developed 3-5 years later, as the study group. The CC16 genotype was determined by PCR and Sau96I restriction digestion of PCR products. The serum CC16 levels were measured by ELISA. Total serum IgE, allergen specific IgE, eosinophil count and pulmonary function were also measured.

RESULTS

In children with rhinitis who develop asthma, the frequencies of the AA genotype were significantly higher than those who did not develop asthma [odds ratio (OR)=2.527; 95% confidence interval (CI)=1.571-4.065; P<0.01]. Serum CC16 levels in the children with rhinitis who develop asthma and carry the AA genotype were significantly lower than those who carry the non-AA genotype and those who did not develop asthma.

CONCLUSIONS AND CLINICAL RELEVANCE

Results of this study suggest that CC16 38A/38A genotype plays a role in the development of early asthma in children with AR. Early identification of rhinitis children at risk may assist in designing preventative approach to asthma development.

Exhaled NO among inner-city children in New York City

BACKGROUND

Fractional exhaled nitric oxide (FeNO) has been proposed as a biomarker of airway inflammation for cohort studies of asthma.

OBJECTIVES

To assess the association between FeNO and asthma symptoms among 7-year-old children living in an inner-city community. To test the association between environmental tobacco smoke (ETS) exposure (previous and current) and FeNO among these children.

METHODS

As part of a longitudinal study of asthma, children recruited in Head Start centers at age 4 had offline FeNO and lung function testing at age 7. Children with allergen-specific immunoglobulin E (IgE) (≥0.35 IU/mL) at age 7 were considered seroatopic. ETS exposure at ages 4 and 7 was assessed by questionnaire.

RESULTS

Of 144 participating children, 89 had complete questionnaire data and achieved valid FeNO and lung function tests. Children with reported wheeze in the previous 12 months (n = 19) had higher FeNO than those without wheeze (n = 70) (geometric means 17.0 vs. 11.0 ppb, p = .005). FeNO remained significantly associated with wheeze (p = .031), after adjusting for seroatopy and forced expiratory volume in 1 second (FEV₁) in multivariable regression. FeNO at age 7 was positively associated with domestic ETS exposure at age 4 (29%) (β = 0.36, p = .015) but inversely associated with ETS exposure at age 7 (16%) (β = -0.74, p < .001).

CONCLUSIONS

Given its association with current wheeze, independent of seroatopy and lung function, FeNO provides a relevant outcome measure for studies in inner-city communities. While compelling, the positive association between ETS exposure at age 4 and a marker of airway inflammation at age 7 should be confirmed in a larger study.

Peanut allergy and allergic airways inflammation

Asthma is a major risk cofactor for anaphylactic deaths in children with peanut allergy. Peanut allergy is generally thought to be a lifelong condition, but some children outgrow their coexistent asthma. It has recently been shown that children who have 'outgrown' their asthma symptoms may have ongoing eosinophilic airways inflammation. The need for regular inhaled corticosteroid treatment in peanut allergic children and adolescents who have outgrown their asthma is however unclear. The aims of our study were to look at fractional exhaled nitric oxide levels (FeNO), as a non-invasive marker of eosinophilic airways inflammation, in peanut allergic children and assess whether children with outgrown asthma had elevated levels. Children with peanut allergy were recruited at two pediatric allergy clinics in Belfast, UK. Exhaled nitric oxide levels (FeNO) were measured using the Niox Mino in all children. Of the 101 peanut allergic children who consented for enrollment in the study, 94 were successfully able to use the NIOX Mino. Age range was 4-15 yr (median 10 yr); 61% were boys. Thirty (32%) had never wheezed, 37 (39%) had current treated asthma, 20 (21%) had at least 1 wheezing episode within the last year but were not taking any regular asthma medication (wheeze no treatment), and 7 (7%) had outgrown asthma. All children with outgrown asthma had elevated levels of FeNO (> 35 ppb), and 75% of children defined as 'wheeze no treatment' had elevated FeNO levels (> 35 ppb). Outgrown asthma and children defined as 'wheeze no treatment' had higher levels of FeNO than those with no history of wheeze or current treated asthma (p = 0.003). In children with peanut allergy, we found that those who had outgrown asthma had elevated FeNO levels in keeping with ongoing eosinophilic airways inflammation.

Feline-specific serum total IgE quantitation in normal, asthmatic and parasitized cats

Immunoglobulin E (IgE) plays an important role in defense against parasitic infections as well as allergy. Knowledge of serum total IgE concentrations may have value in diagnosis and prognostication of various disorders; however, to date, no studies have reported feline serum total IgE concentrations. We hypothesize that serum total IgE concentrations will be greater in spontaneously parasitized and asthmatic cats compared to healthy pet cats. Healthy (n=10), parasitized (10) and asthmatic cats (eight) had measurement of serum total IgE by ELISA. Data were analyzed using a t-test with P<0.05 considered significant. Serum total IgE was higher in parasitized (mean±SEM, 328.4±123.8μg/ml; P<0.028) and asthmatic cats (85.5±19.5μg/ml; P<0.047) compared to healthy cats (45.9±19.6μg/ml). However, serum total IgE had poor discriminatory capability between diseased and healthy cats. In conclusion, this assay can detect small quantities of feline serum total IgE, which may be beneficial in future studies of parasitism or allergic disease.

Impact of rhinitis on asthma control in children: association with FeNO

BACKGROUND

The prevalence of rhinitis is high and frequently observed in association with asthma. Although the persistence of predisposing factors such as rhinitis is frequently observed in adults, this has not yet been confirmed in children.

AIMS

The aim of this present work is to show the relationship between rhinitis and asthma control in asthmatic children.

METHODS

The authors carried out a cross-sectional study by collecting clinical, spirometric, and fractional exhaled nitric oxide (FeNO) data in children aged from 4 to 17 years.

RESULTS

One hundred seventeen children were included. Asthma control was optimal in 37.6%, suboptimal in 55.5% and poor in 7.3% of cases. A 74.3% of children were atopic and 62.5% had symptoms 34 of rhinitis. Rhinitis was more frequent when control of asthma was worse (p = .0001). Age (p = .002), asthma control (p < .001), atopy (p = .001), and presence of rhinitis (p = .012) were significantly associated with FeNO.

CONCLUSIONS

Our study confirms the strong relationship between upper airways and poor asthma control in the asthmatic child. Symptoms of rhinitis may be partly responsible for the increased fractional exhaled nitric oxide (FeNO) level, independently of the control of asthma. Evaluation of rhinitis should be included to improve assessment of asthma control in children.

Factors attributable to the level of exhaled nitric oxide in asthmatic children

Background

Asthma is a heterogeneous disease with variable symptoms especially in children. Exhaled nitric oxide (FeNO) has proved to be a marker of inflammation in the airways and has become a substantial part of clinical management of asthmatic children due to its potential to predict possible exacerbation and adjust the dose of inhalant corticosteroids.

Objectives

We analyzed potential factors that contribute to the variability of nitric oxide in various clinical and laboratory conditions.

Materials and methods

Study population consisted of 222 asthmatic children and 27 healthy control subjects. All children underwent a panel of tests: fractioned exhaled nitric oxide, exhaled carbon monoxide, asthma control test scoring, blood sampling, skin prick tests, and basic spirometry.

Results

FeNO and other investigated parameters widely changed according to clinical or laboratory characteristics of the tested children. Asthmatics showed increased levels of FeNO, exhaled carbon monoxide, total serum IgE, and higher eosinophilia. Boys had higher FeNO levels than girls. We found a significant positive correlation between FeNO levels and the percentage of blood eosinophils, %predicted of forced vital capacity, total serum IgE levels, and increasing age.

Conclusions

Various phenotypes of children's asthma are characterized by specific pattern of the results of clinical and laboratory tests. FeNO correlates with total serum IgE, blood eosinophilia, age, and some spirometric parameters with different strength. Therefore, the coexistence of atopy, concomitant allergic rhinitis/rhinoconjunctivitis, and some other parameters should be considered in critical evaluation of FeNO in the management of asthmatic children.

Relationship between exhaled nitric oxide and IgE sensitisation in patients with asthma: influence of steroid treatment

INTRODUCTION

The influence of the degree of immunoglobulin E (IgE) sensitisation on the fraction of expired nitric oxide (FE(NO)) in asthma patients being treated with inhaled corticosteroids (ICS) is not well known.

OBJECTIVES

To investigate the relationship between IgE sensitisation and FE(NO), and the effect of a step-up in ICS treatment on this relationship, in patients with allergic asthma.

METHODS

A primary health care centre recruited 20 non-smoking patients with perennial allergic asthma (18 years-50 years, six male) outside the pollen season. At every visit (0, 2, 4, 8 weeks), FE(NO) was measured and an exposure questionnaire was completed. ICS dose was adjusted according to FE(NO) (>or=22 ppb prescribed increase in ICS). Quantitative analyses of serum IgE (eight common aeroallergens) confirmed allergy.

RESULTS

At baseline, FE(NO) and the sum of IgE antibody titres for perennial allergens correlated significantly (r = 0.47, P = 0.04). After a step-up in ICS treatment, this correlation had disappeared. Nine patients had persistently elevated FE(NO) at last visit (mean 35 ppb vs 16 ppb). This group was more frequently exposed to relevant allergens or colds (89% vs 27% of patients, P < 0.05) and had higher IgE antibody titres (perennial allergens) compared with the normalised group (mean 28.9 kU/L vs 10.7 kU/L, P < 0.05).

CONCLUSION

Serum IgE against perennial allergens and FE(NO) correlate in patients with allergic asthma. However, this relationship disappears after a high-dose ICS regimen, suggesting that FE(NO) relates to bronchial inflammation and not IgE levels per se. High degree of IgE sensitisation together with allergen exposure may lead to ICS-resistant airways inflammation.

Increased exhaled nitrite in children with allergic asthma is not related to nitric oxide formation

INTRODUCTION

Nitrite sampled from the upper airways could originate from inflammation-induced nitric oxide (NO), as reports of elevated nitrite in exhaled breath condensate (EBC) from asthmatics suggest, but also through bacterial action in the pharyngo-oral tract.

OBJECTIVES

To correlate EBC nitrite and nitrate to exhaled NO (FENO, fraction of expired NO) and other markers of disease activity in children with allergic asthma and thereby further investigate their role and origin.

MATERIALS AND METHODS

EBC was collected from 27 asthmatic subjects (ages 6-17 years, all immunoglobulin E-positive for aeroallergens) and 21 age-matched non-atopic healthy controls for fluorometric analysis of nitrite and nitrate. These markers were compared with measurements of FENO, blood eosinophil count (EOS), methacholine reactivity (PD(20)) and baseline spirometry.

RESULTS

EBC nitrite, in contrast to nitrate, was significantly increased (P < 0.01) in the asthmatic children. They also had increased levels of FENO (P < 0.001) and EOS (P < 0.001) along with decreased PD(20) (P < 0.001) and FEV1/FVC (P < 0.01). However, there was no correlation between EBC nitrite and FENO (r = 0.05) or any other marker of disease activity in the asthmatic children, whereas between the other markers correlations could be established.

CONCLUSION

EBC nitrite is elevated in childhood asthma but the lack of correlation to FENO and other markers, together with simultaneously normal levels of nitrate, make its origin as a metabolite of inflammation-induced NO questionable.

FeNO as a Marker of Airways Inflammation: The Possible Implications in Childhood Asthma Management

The aim of this study was to verify FeNO usefulness, as a marker of bronchial inflammation, in the assessment of therapeutic management of childhood asthma. We performed a prospective 1-year randomized clinical trial evaluating two groups of 32 children with allergic asthma: "GINA group", in which therapy was assessed only by GINA guidelines and "FeNO group", who followed a therapeutic program assessed also on FeNO measurements. Asthma Severity score (ASs), Asthma Exacerbation Frequency (AEf), and Asthma Therapy score (ATs) were evaluated at the start of the study (T1), 6 months (T2), and 1 year after (T3). ASs and AEf significantly decreased only in the FeNO group at times T2 and T3 (p[T1-T2] = 0.0001, and p[T1-T3] = 0.01; p[T1-T2] = 0.0001; and p[T1-T3] < 0.0001, resp.). After six months of follow-up, we found a significant increase of patients under inhaled corticosteroid and/or antileukotrienes in the GINA group compared to the FeNO group (P = .02). Our data show that FeNO measurements, might be a very useful additional parameter for management of asthma, which is able to avoid unnecessary inhaled corticosteroid and antileukotrienes therapies, however, mantaining a treatment sufficient to obtain a meaningful improvement of asthma.

Diagnostic value of exhaled nitric oxide in childhood asthma and allergy

Fractional exhaled nitric oxide (FE(NO) ) has been proposed as a diagnostic test of asthma. We aimed to investigate in a population based birth cohort of children the usefulness of FE(NO) as a diagnostic tool. The 10-yr follow up of the Environment and Childhood Asthma Study in Oslo included 616 children representative of the prospective birth cohort. Both FE(NO) (single breath technique) and skin prick test (SPT) were measured in 331, limited at the time by equipment availability. Structural parental interview, spirometry, methacholine challenge and exercise test were performed. FE(NO) was significantly elevated in children with current asthma (geometric mean 9.6 (95% confidence interval (CI) (6.9, 13.4) p.p.b.) compared with healthy children (5.8 (5.4, 6.3) p.p.b.; p < 0.001). FE(NO) was highest among children with current allergic asthma (asthma and positive SPT) (14.0 (8.9, 22.1) p.p.b.), whereas children with non-allergic asthma (6.1 (4.0, 9.2) p.p.b.) had comparable FE(NO) levels to healthy children (p = 0.99). Allergic sensitization was most closely associated with FE(NO) . A FE(NO) cut-off value of 20.4 p.p.b. had a high specificity (0.97), but a low sensitivity (0.41) and a Positive Likelihood Ratio of 16.1 for current allergic asthma. In the present childhood population-based study, high FE(NO) levels were closely associated with current allergic asthma and not with current asthma without allergic sensitization. Estimating the individual predictive probability of having asthma by use of FE(NO,) improves the diagnostic utility of the test.

Differences in exhaled nitric oxide in atopic children

BACKGROUND

Exhaled nitric oxide (FeNO) has been introduced in the diagnosis and control of asthma. Atopy related diseases are a common comorbidity in asthma, but in these cases the FeNO values and their relevance have not been clearly defined. In this study we compared the differences in FeNO levels in various atopic conditions.

METHODS

A prospective study was performed comparing online FeNO in six groups of patients (non-atopic control, asymptomatic atopic, non-active rhinitis, active rhinitis, asthma, asthma with rhinitis).

RESULTS

90 children (15 per group) assisted in an outpatient hospital clinic were enrolled. FeNO levels (ppb) were: 7.9 (non-atopic control), 19 (asymptomatic atopic), 16.6 (non-active rhinitis), 26.3 (active rhinitis), 31 (asthma), and 35 (asthma and rhinitis). All groups presented higher levels of FeNO than the non-atopic control group (P < 0.001). Both asthma groups had higher levels than the rest of the groups (P < 0.05), except for the active rhinitis group. Dispersion of FeNO levels was wide in the study sample. No correlation was found between FeNO and FEV(1). A weak correlation was seen with age (r = 0.28)

CONCLUSIONS

Atopy, rhinitis and its exacerbations can be confounders in the interpretation of FeNO levels in asthmatic children.

Fractional exhaled nitric oxide in infants during cow's milk food challenge

Cow's milk allergy (CMA) is the most common food allergy in early childhood. The golden standard for the diagnosis of CMA is a food challenge after a period of elimination. Increased levels of fractional exhaled nitric oxide (FE(NO)) have been shown after bronchial allergen provocation. We evaluated whether FE(NO) may also be a predictor of a positive reaction during cow's milk challenge in infants. Forty-four infants [mean age (range): 4.2 (3.7-4.6) months] suspected of CMA underwent an open food challenge with cow's milk formula administered in ascending quantities, starting with 2 ml and then 6, 20, 60 and 200 ml until a clinical reaction occurred. Off-line FE(NO) samples were obtained during tidal breathing by means of a facemask covering infants' nose and mouth. FE(NO) was measured twice before the challenge (baseline), immediately before each new dose of milk and after a positive reaction or after the last dose of milk. Eleven children showed immediate positive clinical responses to cow's milk, whereas 13 infants presented only a late-type reaction. FE(NO) values before or after a positive reaction (either immediate or late) were not different from FE(NO) values at baseline. Baseline FE(NO) in infants with a positive reaction did not differ from FE(NO) in infants without a reaction at any time point. We conclude that FE(NO) values are not predictive and not related to the occurrence of a positive reaction during a cow's milk challenge in infants, suggesting that a positive reaction may not result from eosinophilic activation.

Increased bronchial NO output in severe atopic eczema in children and adolescents

Atopic children have an increased risk for asthma, which is preceded by bronchial inflammation. Exhaled nitric oxide (NO) measured at multiple exhalation flow rates can be used to assess alveolar NO concentration and bronchial NO flux, which reflect inflammation in lung periphery and central airways, respectively. Exhaled breath condensate is another non-invasive method to measure lung inflammation. The purpose of the present study was to find out if the severity of atopic eczema is associated with lung inflammation that can be observed with these non-invasive tests. We studied 81 patients (7-22 yr old) with atopic eczema and increased wheat-specific IgE (>or=0.4 kUA/l) and no diagnosis of asthma. Exhaled NO was measured at multiple exhalation flow rates, and bronchial NO flux and alveolar NO concentration were calculated. Cysteinyl-leukotriene concentrations were measured in exhaled breath condensate. The patients were divided into two groups according to the severity of atopic eczema. Patients with severe atopic eczema had enhanced bronchial NO output as compared with patients with mild eczema (2.1 +/- 0.5 vs. 0.9 +/- 0.1, p = 0.003). No statistically significant differences in alveolar NO concentrations were found between the groups. In the whole group of patients, the bronchial NO output correlated positively with serum eosinophil protein X (r(s) = 0.450, p < 0.001), serum eosinophil cationic protein (r(s) = 0.393, p < 0.001), serum total IgE (r(s) = 0.268, p = 0.016) and with urine eosinophil protein X (r(s) = 0.279, p = 0.012), but not with lung function. Alveolar NO concentration correlated positively with serum eosinophil protein X (r(s) = 0.444, p < 0.001) and with serum eosinophil cationic protein (r(s) = 0.362, p = 0.001). Measurable cysteinyl-leukotriene concentrations in exhaled breath condensate were found only in one-third of the patients, and there were no differences between the two groups. The results show that increased bronchial NO output is associated with eosinophilic inflammation and severe atopic eczema in patients without established asthma.

Exhaled nitric oxide in childhood asthma: a review

As an 'inflammometer', the fraction of nitric oxide in exhaled air (Fe(NO)) is increasingly used in the management of paediatric asthma. Fe(NO) provides us with valuable, additional information regarding the nature of underlying airway inflammation, and complements lung function testing and measurement of airway hyper-reactivity. This review focuses on clinical applications of Fe(NO) in paediatric asthma. First, Fe(NO) provides us with a practical tool to aid in the diagnosis of asthma and distinguish patients who will benefit from inhaled corticosteroids from those who will not. Second, Fe(NO) is helpful in predicting exacerbations, and predicting successful steroid reduction or withdrawal. In atopic asthmatic children Fe(NO) is beneficial in adjusting steroid doses, discerning those patients who require additional therapy from those whose medication dose could feasibly be reduced. In pre-school children Fe(NO) may be of help in the differential diagnosis of respiratory symptoms, and may potentially allow for better targeting and monitoring of anti-inflammatory treatment.

Factors affecting exhaled nitric oxide measurements: the effect of sex

Background

Exhaled nitric oxide (F_ENO) measurements are used as a surrogate marker for eosinophilic airway inflammation. However, many constitutional and environmental factors affect F_ENO, making it difficult to devise reference values. Our aim was to evaluate the relative importance of factors affecting F_ENO in a well characterised adult population.

Methods

Data were obtained from 895 members of the Dunedin Multidisciplinary Health and Development Study at age 32. The effects of sex, height, weight, lung function indices, smoking, atopy, asthma and rhinitis on F_ENO were explored by unadjusted and adjusted linear regression analyses.

Results

The effect of sex on F_ENO was both statistically and clinically significant, with F_ENO levels approximately 25% less in females. Overall, current smoking reduced F_ENO up to 50%, but this effect occurred predominantly in those who smoked on the day of the F_ENO measurement. Atopy increased F_ENO by 60%. The sex-related differences in F_ENO remained significant (p < 0.001) after controlling for all other significant factors affecting F_ENO.

Conclusion

Even after adjustment, F_ENO values are significantly different in males and females. The derivation of reference values and the interpretation of F_ENO in the clinical setting should be stratified by sex. Other common factors such as current smoking and atopy also require to be taken into account.

Exhaled nitric oxide: interactions between asthma, hayfever, and atopic dermatitis in school children

BACKGROUND

Clinicians frequently rely on reported symptoms and basic pulmonary function testing to assess asthma prevalence in the community. However, given that spirometry results are often normal for asthmatic children and the fact that there is no equivalent word for 'wheeze' in languages other than English, the assessment of asthma prevalence can be troublesome.

OBJECTIVE

To evaluate in a population based setting, whether FeNO as a non-invasive marker, contributes to the detection of asthma.

METHODS

This cross-sectional study was carried out on primary school children from Northern and Southern Tyrol. FeNO measurements were made using the online single breath technique prior to spirometry. Symptom status including asthma, hayfever and atopic dermatitis was determined by the ISAAC questionnaire.

RESULTS

Six hundred and forty-four Tyrolean children aged 8-10 years participated. In terms of FEV1 % predicted, the asthma and hayfever group had significantly lower values compared to the asymptomatic group, the hayfever only, and the atopic dermatitis only groups. For FeNO, participants with asthma and hayfever, asthma and atopic dermatitis, and hayfever only recorded significantly greater FeNO values when compared to the asymptomatic group. Moreover, the asthma and atopic dermatitis group recorded significantly greater FeNO when compared to the asthma only group. Multivariate regression revealed that asthma had a small significant inverse association with FEV1 % predicted for the individual model and when combined with hayfever. For FeNO, each of the individual and combined model analyses achieved significance.

CONCLUSION

Although FeNO appears to be influenced by asthma, the presence of other atopic conditions confounds the relationship. Elevated levels of FeNO do not distinguish between asthma and other atopic conditions. Therefore, FeNO does not contribute to the detection of asthma in the community.

CLINICAL IMPLICATION

FeNO is not a valuable tool for the detection of asthma in the community as it is confounded by other atopic conditions.

Infant swimming practice, pulmonary epithelium integrity, and the risk of allergic and respiratory diseases later in childhood

OBJECTIVE

Irritant gases and aerosols contaminating the air of indoor swimming pools can affect the lung epithelium and increase asthma risk in children. We evaluated the impact of infant swimming practice on allergic status and respiratory health later in childhood.

METHODS

Clara cell protein, surfactant-associated protein D, and total and aeroallergen-specific immunoglobulin E were measured in the serum of 341 schoolchildren aged 10 to 13 years, among whom 43 had followed an infant swimming program. Asthma was defined as doctor-diagnosed asthma and/or positive exercise-induced bronchoconstriction (15% decrease in postexercise forced expiratory volume).

RESULTS

There were no significant differences between the infant swimming group and the other children regarding the levels of exhaled nitric oxide and total or aeroallergen-specific serum immunoglobulin E. Children who swam as infants showed, by contrast, a significant decrease of serum Clara cell protein and of the serum Clara cell protein/surfactant-associated protein D ratio integrating Clara cell damage and permeability changes of the lung epithelial barrier. These effects were associated with higher risks of asthma and of recurrent bronchitis. Passive exposure to tobacco alone had no effect on these outcomes but seemed to interact with infant swimming practice to increase the risk of asthma or of recurrent bronchitis.

CONCLUSIONS

Our data suggest that infant swimming practice in chlorinated indoor swimming pools is associated with airways changes that, along with other factors, seem to predispose children to the development of asthma and recurrent bronchitis.