Aeroallergen and food IgE sensitization and local and systemic inflammation in asthma

Impact of wheat sensitization on wheeze and T2 phenotypes in general population of children

Background

The association between sensitization to specific aeroallergens and outcomes in patients with asthma is well researched; however, the association between childhood-onset wheeze/asthma and sensitization to various aeroallergens and food allergens in the general pediatric population remains poorly understood.

Objective

We sought to investigate the association between sensitization to common aeroallergens and food allergens with wheeze and type 2 (T2) inflammation in the general pediatric population.

Methods

Specific IgEs against 9 aeroallergens and 4 food allergens were measured in the prospective Hokkaido birth cohort of 428 school-age children (age ∼10 years). Wheeze and other allergic symptoms were assessed using the International Study of Asthma and Allergies in Childhood questionnaire. Blood eosinophil count and fractional exhaled nitric oxide level were assessed as T2 biomarkers. The Isle of Wight birth cohort in the United Kingdom was used for replication analysis (n = 1032).

Results

The prevalence of sensitization to at least 1 aeroallergen and food allergen was 70.5% and 22.3%, respectively. A significant association between wheeze and sensitization to aeroallergens such as ragweed, Japanese cedar, mugwort, and pet dander was found. However, the association between wheeze and wheat sensitization was highly significant (Hokkaido birth cohort: odds ratio, 4.67; 95% CI, 1.98-11.01; Isle of Wight birth cohort, odds ratio, 4.01; 95% CI, 1.78-9.07). Sensitization to most aeroallergens, though not any food allergen, was associated with the T2-high phenotype.

Conclusions

Sensitization to wheat may be an important risk factor for wheeze/asthma development, especially the pathogenesis of T2-non/low asthma, independent of aeroallergens, in the general pediatric population.

Multiarray screening identifies plasma proteins associated with Th17 cell differentiation and viral defense in coincident asthma and obesity

BACKGROUND

The immunological mechanisms behind the clinical association between asthma and obesity in adolescence are not fully understood. This study aimed to find new plasma protein biomarkers associated specifically with coincident asthma and obesity in adolescents.

METHODS

This was a cross-sectional study in children and adolescents 10-19 years old (N = 390). Relative plasma concentrations of 113 protein biomarkers related to inflammation and immune response were determined by proximity extension assay (Target 96; Olink, Uppsala, Sweden). Differences in protein concentrations between healthy controls (n = 84), subjects with asthma (n = 138), subjects with obesity (n = 107), and subjects with both asthma and obesity (AO; n = 58) were analyzed by ANCOVA, adjusting for age and sex, and in a separate model adjusting also for the sum of specific IgE antibody concentrations to a mix of food allergens (fx5) and aeroallergens (Phadiatop). Proteins elevated in the AO group but not in the obesity or asthma groups were considered specifically elevated in asthma and obesity.

RESULTS

Five proteins were elevated specifically in the AO group compared to controls (here sorted from largest to smallest effect of asthma and obesity combined): CCL8, IL-33, IL-17C, FGF-23, and CLEC7A. The effects of adjusting also for specific IgE were small but IL-33, IL-17C, and FGF-23 were no longer statistically significant.

CONCLUSION

We identified several new potential plasma biomarkers specifically elevated in coincident asthma and obesity in adolescents. Four of the proteins, CCL8, IL-33, IL-17C, and CLEC7A, have previously been associated with viral mucosal host defense and Th17 cell differentiation.

Sensitization patterns to cat molecular allergens in subjects with allergic sensitization to cat dander

BACKGROUND

The use of molecular allergology has increasingly become common in the diagnosis and management of allergic diseases. However, there is still a lack of data on cat molecular allergens in adults. Therefore, we aimed to uncover the sensitization patterns to cat molecular allergens.

METHODS

Participants were recruited from the West Asthma Sweden Study, a population-based study enriched with asthma subjects aged 16-75 years. Of 1872, 361 individuals were positive for cat dander immunoglobulin E and were further analysed for cat molecular allergens (Fel d 1/2/4/7). Sensitization patterns were classified as monosensitization, polysensitization, and concomitant sensitization, and were related to demographic and clinical measurements.

RESULTS

Among cat-sensitized subjects, 84.2% were sensitized to secretoglobin, while 42.4% were sensitized to lipocalins. Nearly half of the subjects were monosensitized to Fel d 1. Polysensitization was observed in 20.2%, and concomitant sensitization to protein families was seen in 7.2%. Asthma prevalence, cat exposure, and rural living were associated with poly- and concomitant sensitization to protein families. Concomitant sensitization to single allergens was more common in those with asthma than in those without, while concomitant sensitization to both Fel d 1 and Fel d 4 was the most common pattern in individuals with asthma. Sensitization patterns also differed according to cat ownership and the degree of urbanization.

CONCLUSION

Sensitization to molecular allergens was observed in 90.9% of cat-sensitized subjects and showed variations across participants' background characteristics and the presence of asthma. Identification of sensitization patterns to cat allergens might provide better characterization of cat-allergic subjects.

Development of sensitization to peanut and storage proteins and relation to markers of airway and systemic inflammation: A 24-year follow-up

BACKGROUND

Long-time data of peanut allergy over time is sparse. We aimed to study the longitudinal development of sensitization to peanut extract and storage protein allergen molecules and associations with asthma status, airway and systemic inflammation markers.

METHODS

The Swedish birth cohort BAMSE followed 4089 participants with questionnaires, clinical investigations and blood sampling between 0 and 24 years. Information on (i) background factors at 2 months, (ii) peanut allergy symptoms and IgE data (ImmunoCAP) at 4, 8, 16, and 24 years, and (iii) IgE to storage proteins, lung function data including exhaled nitric oxide (FENO) as well as systemic inflammatory markers at 24 years of age were collected.

RESULTS

The prevalence of peanut extract sensitization, defined as IgE ≥ 0.35 kU_A /L, was 5.4%, 8.0%, 7.5%, and 6.2% at 4, 8, 16, and 24 years of age, respectively. Between 8 and 24 years of age, (33/1565) participants developed IgE-ab to peanut extract (median 1,4, range 0.7-2.6 kU_A /L), and among those 85% were also sensitized to birch. Only six individuals developed sensitization to Ara h 2 (≥0.1 kU_A /L) between 8 and 24 years of age, of whom three had an IgE-ab level between 0.1-0.12 kU_A /L. Storage protein sensitization was associated with elevated FENO, blood eosinophils and type 2 inflammation-related systemic proteins.

CONCLUSION

Sensitization to peanut extract after 4 years of age is mainly induced by birch cross-sensitization and IgE to Ara h 2 rarely emerges after eight years of age. Storage protein sensitization is associated with respiratory and systemic inflammation.

Blood eosinophil counts in the general population and airways disease: a comprehensive review and meta-analysis

BACKGROUND

The clinical context for using blood eosinophil (EOS) counts as treatment-response biomarkers in asthma and COPD requires better understanding of EOS distributions and ranges. We describe EOS distributions and ranges published in asthma, COPD, control (non-asthma/COPD) and general populations.

METHODS

We conducted a comprehensive literature review and meta-analysis of observational studies (January 2008 to November 2018) that included EOS counts in asthma, severe asthma, COPD, control and general populations. Excluded studies had total sample sizes <200, EOS as inclusion criterion, hospitalised population only and exclusively paediatric participants.

RESULTS

Overall, 91 eligible studies were identified, most had total-population-level data available: asthma (39 studies), severe asthma (12 studies), COPD (23 studies), control (seven studies) and general populations (14 studies); some articles reported data for multiple populations. Reported EOS distributions were right-skewed (seven studies). Reported median EOS counts ranged from 157-280 cells·µL-1 (asthma, 22 studies); 200-400 cells·µL-1 (severe asthma, eight studies); 150-183 cells·µL-1 (COPD, six studies); and 100-160 cells·µL-1 (controls, three studies); and 100-200 cells·µL-1 (general populations, six studies). The meta-analysis showed that observed variability was mostly between studies rather than within studies. Factors reportedly associated with higher blood EOS counts included current smoking, positive skin-prick test, elevated total IgE, comorbid allergic rhinitis, age ≤18 years, male sex, spirometric asthma/COPD diagnosis, metabolic syndrome and adiposity.

CONCLUSION

EOS distribution and range varied by study population, and were affected by clinical factors including age, smoking history and comorbidities, which, regardless of severity, should be considered during treatment decision-making.

Relationship between longitudinal changes in type-2 inflammation, immunoglobulin E sensitization, and clinical outcomes in young asthmatics

BACKGROUND

Asthma is a heterogeneous condition where biomarkers may be of considerable advantage in diagnosis and therapy monitoring. However, the changes in asthma biomarkers and immunoglobulin E (IgE) over the course of life has not been extensively investigated.

OBJECTIVE

To study longitudinal changes in type-2 inflammatory biomarkers, IgE, and clinical outcomes, and the association between these changes, in young asthmatics.

METHODS

Asthmatics (age 10-35 years, n = 253) were examined at baseline and at a follow-up visit, 43 [23-65] (median [range]) months later. Subjects were analyzed using the multi-allergen tests Phadiatop and fx5 (ImmunoCAP) and grouped based on the baseline allergen-specific IgE antibody (sIgE) concentration: <0.10, 0.10-0.34, and ≥0.35 kU_A /L. The relationship between changes (Δ values) in type-2 biomarkers (individualized fraction of exhaled nitric oxide [FeNO%], blood eosinophil [B-Eos] count, total IgE [tIgE] and sIgE, lung function [% predicted forced expiratory volume in 1 second (FEV₁ ) and FEV₁ /forced vital capacity (FVC)], and Asthma Control Test [ACT]) score were determined.

RESULTS

At follow up, FEV₁ and FEV₁ /FVC had decreased (93.6% vs. 95.8%, and 93.4% vs. 94.7% of predicted, respectively [p < 0.001 both]), whereas ACT score had increased (21.6 vs. 20.6, p = 0.001). A significant decline in lung function was seen in subjects with sIgE ≥ 0.10 kUA/L, but not in those with undetectable sIgE (<0.10 kU_A /L). Furthermore, tIgE and sIgE declined over time (p < 0.001 all) whereas FeNO% and B-Eos count were not significantly changed. In univariate analysis, significant negative correlations between ∆B-Eos count and ∆FeNO%, on one hand, and changes in lung function, on the other hand, were seen, and multivariate analysis showed an independent relationship between ΔFeNO%, and ΔFEV₁ (p < 0.05) and ΔFEV₁ /FVC% (p < 0.01). Sex-specific analysis showed that the independent association between ΔFeNO%, and ΔFEV₁ remained only in females (p = 0.005), and there was a significant interaction with sex (p = 0.02).

CONCLUSION

In young asthmatics, IgE levels declined over 43 months, whereas FeNO and B-Eos remained unchanged. In spite of improved asthma control, an accelerated lung function decline was seen in patients with detectable sIgE at baseline, and the decline correlated with changes in type-2 biomarkers. Particularly, the increase in individualized FeNO associated independently with decline in FEV₁ in females.

Importance of type and degree of IgE sensitisation for defining fractional exhaled nitric oxide reference values

BACKGROUND

Fractional exhaled nitric oxide (FE_NO) is a marker of type 2 airway inflammation used in clinical practice in asthma. However, reference values are needed to broaden the clinical use of FE_NO and this is within the scope of a newly started Global Lung Function Initiative task force. We aim to study FE_NO levels with special emphasis on the upper limit of normal (ULN) in relation to the type and degree of IgE sensitisation.

METHODS

FE_NO was measured in 1855 non-smoking, respiratory healthy subjects from the Swedish CArdioPulmonary bioImage Study (SCAPIS). Atopic subjects (n = 424), defined as being IgE-sensitised to aeroallergens (ImmunoCAP Phadiatop™, ≥0.35 PAU/l) were compared to non-atopic subjects (<0.35 PAU/l, n = 1431). Atopic subjects were further characterised according to their grade of IgE sensitisation (IgE antibody tertiles: (T1<1.16, T2 1.16-3.72 and T3 >3.72 PAU/l) and sensitisation to perennial (cat or mite) or seasonal (birch) allergens.

RESULTS

Subjects IgE-sensitised to cat or mite had higher FE_NO compared to non-atopic subjects (FE_NO (ppb): median 20.0 vs. 15.0, and ULN 50.4 vs. 33.0, p < 0.001). This was seen to a lesser extent for subjects IgE-sensitised to birch only (median 18.0 vs. 15.0, and ULN 38.0 vs. 33.0, p = 0.048). Atopic subjects with a high degree of IgE sensitisation (Phadiatop: >3.72 PAU/l) had the highest FE_NO compared to non-atopic subjects (median 20.0 vs. 15.0, and ULN 56.0 vs. 33.0, p < 0.001).

CONCLUSIONS

The type and degree of IgE sensitisation should be considered in generating FE_NO reference values.

Characterization of Asthma Trajectories from Infancy to Young Adulthood

BACKGROUND

Development of asthma is complicated by the multidimensional nature of the disease.

OBJECTIVE

To identify and characterize trajectories of asthma from infancy to young adulthood, and their associations with lung function and inflammatory and respiratory markers in adolescence and young adulthood.

METHODS

A latent class analysis was performed in a population-based cohort (N = 4089). Parental and self-reported symptoms of asthma were used to investigate asthma development. We characterized background factors, allergic comorbidity, and IgE sensitization and investigated associations with asthma markers.

RESULTS

A 4-class solution of asthma trajectories was identified: never/infrequent (n = 3291 [80.4%]), early-onset transient (n = 307 [7.5%]), adolescent-onset (n = 261 [6.4%]), and persistent asthma (n = 230 [5.6%]). Uncontrolled asthma was equally prevalent in the adolescent-onset and persistent asthma trajectory groups, at both age 16 (41.7% vs 42.4%; P = .90) and 24 years (53.7% vs 52.4%; P = .81). The persistent asthma trajectory group had a higher proportion of eosinophil counts greater than or equal to 0.3 (10⁹ cells/L) at age 24 years compared with the adolescent-onset trajectory group (31.0% vs 18.5%; P < .01).

CONCLUSIONS

The adolescent-onset and persistent asthma trajectory groups had equal burdens of asthma control in adolescence and young adulthood. However, the persistent asthma trajectory group showed more signs of type 2 inflammation than the adolescent-onset trajectory group. This unbiased approach highlights the need of identifying patients with adolescent asthma to optimize care, because they suffer the same lack of asthma control as those with persistent asthma.

Nasal nitric oxide in relation to asthma characteristics in a longitudinal asthma cohort study

OBJECTIVE

Cross-sectional studies report relations between low nasal nitric oxide (nNO) and poor asthma control and between low nNO and chronic rhinosinusitis (CRS). In our cohort study, we studied if changes in nNO related to changes in asthma control, symptoms of CRS, or asthma or rhinitis medication.

METHODS

A total of 196 subjects with predominantly mild to moderate asthma, aged 10-35 years, performed nNO measurements at both baseline and follow-up after a median of 43 (range 23-65) months. Asthma control, CRS symptoms, and medication, were questionnaire-assessed at both timepoints. IgE sensitisation against aeroallergens was quantified at baseline.

RESULTS

There was an increase in nNO between baseline and follow-up (764 ± 269 ppb vs. 855 ± 288 ppb, p < 0.001). When adjusted for covariates, a larger increase in nNO was found in subjects sensitised to perennial aeroallergens than those not sensitised (92 (16-167) ppb), as well as in subjects with daily use of inhaled corticosteroids (ICS) at baseline but not at follow-up than those on ICS daily at both timepoints (146 (51-242) ppb). In the same model, subjects using nasal steroids daily at both timepoints had decreased nNO compared with those without such treatment at both timepoints (-185 (-321-(-48)) ppb). No relations between changes in nNO levels and changes in asthma control or symptoms of CRS were found.

CONCLUSION

Longitudinal changes in nNO were not related to changes in asthma control, but were related to changes in asthma or rhinitis medication.

Circulating mast cell progenitors correlate with reduced lung function in allergic asthma

BACKGROUND

Studies using mouse models have revealed that mast cell progenitors are recruited from the blood circulation to the lung during acute allergic airway inflammation. The discovery of a corresponding human mast cell progenitor population in the blood has enabled to study the relation of circulating mast cell progenitors in clinical settings.

OBJECTIVES

To explore the possible association between the frequency of mast cell progenitors in the blood circulation and allergic asthma, we assessed the relation of this recently identified cell population with asthma outcomes and inflammatory mediators in allergic asthmatic patients and controls.

METHODS

Blood samples were obtained, and spirometry was performed on 38 well-controlled allergic asthmatic patients and 29 controls. The frequency of blood mast cell progenitors, total serum IgE and 180 inflammation- and immune-related plasma proteins were quantified.

RESULTS

Allergic asthmatic patients and controls had a similar mean frequency of blood mast cell progenitors, but the frequency was higher in allergic asthmatic patients with reduced FEV₁ and PEF (% of predicted) as well as in women. The level of fibroblast growth factor 21 (FGF-21) correlated positively with the frequency of mast cell progenitors, independent of age and gender, and negatively with lung function. The expression of FcεRI on mast cell progenitors was higher in allergic asthmatic patients and correlated positively with the level of total IgE in the controls but not in the asthmatic patients.

CONCLUSION

Elevated levels of circulating mast cell progenitors are related to reduced lung function, female gender and high levels of FGF-21 in young adults with allergic asthma.

Sensitization to storage proteins in peanut and hazelnut is associated with higher levels of inflammatory markers in asthma

Background

Sensitization to peanuts and hazelnuts is common among young asthmatics and can be primary or a result of cross-reactivity. Sensitization as a result of cross-reactivity to birch pollen is typically associated to tolerance or mild and local symptoms upon intake of peanut or hazelnut.

Aim

The aim of this study was to investigate relationships between IgE antibody responses against peanut and hazelnut components, airway and systemic inflammation markers, lung function parameters and reported food hypersensitivity in a cohort of asthmatic children and young adults.

Methods

A population of 408 asthmatic individuals aged 10-35 years were investigated. Information on hypersensitivity symptoms upon intake of peanut or hazelnut were recorded in a standardized questionnaire. Fraction of exhaled nitric oxide (FeNO), blood eosinophil count (B-Eos), spirometry, methacholine challenge outcome and IgE antibodies to peanut and hazelnut allergens were measured by standard clinical and laboratory methods.

Results

Subjects sensitized to any of the peanut (Ara h 1, 2 or 3) or hazelnut (Cor a 9 or 14) storage proteins were significantly younger (17.6 vs 21.2 years), had higher levels of FeNO (23.2 vs 16.7 ppb) and B-Eos (340 vs 170 cells/mcl) than those displaying only pollen-related cross-reactive sensitization. Levels of FeNO correlated with levels of IgE to storage proteins in children, but not in adults. Levels of B-Eos correlated with levels of IgE to all allergen components investigated in children, but only to levels of IgE to storage proteins in adults. Anaphylaxis and skin reactions upon intake of peanuts or hazelnuts were more often reported among subjects sensitized to the respective storage proteins than among those with only pollen-related cross-reactive sensitization. As compared to peanut, hazelnut was more often reported to cause gastrointestinal symptoms and less often oral cavity symptoms.

Conclusions

Sensitization to peanut and hazelnut storage proteins was associated with higher levels of inflammation markers and food hypersensitivity symptoms in this population of subjects with asthma.

Blood eosinophil count in the general population: typical values and potential confounders

There is growing interest in blood eosinophil counts in the management of chronic respiratory conditions such as asthma and chronic obstructive pulmonary disease (COPD). Despite this, typical blood eosinophil levels in the general population, and the impact of potential confounders on these levels have not been clearly defined.We measured blood eosinophil counts in a random sample of 11 042 subjects recruited from the general population in Austria. We then: 1) identified factors associated with high blood eosinophil counts (>75th percentile); and 2) excluded subjects with these factors to estimate median blood eosinophil counts in a "healthy" sub-population (n=3641).We found that: 1) in the entire cohort, age ≤18 years (OR 2.41), asthma (OR 2.05), current smoking (OR 1.72), positive skin prick test (OR 1.64), COPD (OR 1.56), metabolic syndrome (OR 1.41), male sex (OR 1.36) and obesity (OR 1.16) were significantly (p<0.05) associated with high blood eosinophil counts (binary multivariable logistic regression analysis), and had an additive effect; and 2) after excluding these factors, in those older than 18 years, blood eosinophil counts were higher in males than in females (median 120 (5%-95% CI: 30-330) versus 100 (30-310) cells·µL^-1, respectively) and did not change with age.Median blood eosinophil counts in adults are considerably lower than those currently regarded as normal, do not change with age beyond puberty, but are significantly influenced by a variety of factors which have an additive effect. These observations will contribute to the interpretation of blood eosinophil levels in clinical practice.

Concurrence of elevated FeNO and airway hyperresponsiveness in nonasthmatic adolescents

OBJECTIVES

The aim of this study was to investigate airway responsiveness and eosinophil and neutrophil inflammatory markers in clinically confirmed nonasthmatic adolescents with elevated fractional exhaled nitric oxide (FeNO), a marker of type-2 inflammation in the airways.

METHODOLOGY

A total of 959 subjects from a general population, aged 12 to 15 years, answered a standardised questionnaire and underwent FeNO measurements at a screening visit at school. Adolescents without asthma, who had elevated FeNO (FeNO₁₀₀  > 15 ppb) (n = 19), and control subjects, with low FeNO (FeNO₁₀₀  < 5 ppb) and without reported symptoms of asthma or allergy (n = 28), participated in a follow-up study where FeNO₅₀ , airway responsiveness to methacholine (PD₂₀ ), blood eosinophil counts, and serum neutrophil lipocalin (HNL) and myeloperoxidase (MPO) levels were measured. Questionnaire follow-ups were performed 4 and 16 years later.

RESULTS

Airway responsiveness (PD₂₀ : 6.94 [1.87, 11.39] vs 11.42 [6.33, 59.4] µmol; P < .05) and blood eosinophil counts (0.31 [0.20, 0.44] vs 0.13 [0.1, 0.22] 10⁹ /L; P < .001) (geometric mean [95% CI]) were higher among cases than controls. A significant correlation between blood eosinophils and FeNO was found (rho = 0.41; P = .005). In contrast, serum HNL and MPO were lower in cases than controls (P < .05 both), and there was a negative correlation between HNL and FeNO (r = -0.31; P = .04). At both follow-ups, a higher proportion of subjects reported allergic symptoms compared with baseline (P = .02, P = .01).

CONCLUSIONS

Elevated FeNO in nonasthmatic adolescents was associated with airway hyperresponsiveness, elevated blood eosinophil counts, and lower systemic activation of neutrophils.

Anisakis Sensitization in the Croatian fish processing workers: Behavioral instead of occupational risk factors?

We undertook the first study systematically evaluating the risk of Anisakis-sensitization in Croatian fish-processing workers and potential genetic susceptibility to anisakiasis. Anti-Anisakis IgE seroprevalence and risk factors for 600 employees of Croatian fish processing facilities and 466 blood donor controls, were assessed by indirect ELISA targeted with: recombinant Ani s 1 and Ani s 7 allergens, an Anisakis crude extract, the commercial ImmunoCAP kit, and questionnaires. Genetic susceptibility to anisakiasis was evaluated by genotypisation of human leukocytes alleles (HLA). Anti-Anisakis seropositive and a fraction of negative subjects were also assessed by ELISA and Western Blot (WB) for IgG seroprevalence to Trichinella spp. Overall, the observed anti-Anisakis seroprevalence inferred by indirect ELISA was significantly higher in fish processing workers (1.8%, 95% CI 0.9–3.3%) compared to the controls (0%, 0–0.8%). Seven out of 11 Ani s 1 and Ani s 7-positives and none of selected 65 negative sera, tested positive on whole-Anisakis extract (ImmunoCAP), whereas Anisakis crude extract ELISA detected 3.9% (2.4–6.0%) seropositives in fish processing workers, three (14%) of which showed IgE reactivity to milk proteins. The highest risk associated with Anisakis-sensitization among workers was fishing in the free time, rather than any of attributes related to the occupational exposure. Although no association was observed between anti-Anisakis seropositivity and wearing gloves or protective goggles, the majority of workers (92%) wore protective gloves, minimizing the risk for Anisakis sensitization via skin contact. Six HLA alleles within DRB1 gene were significantly associated with seropositivity under dominant, allelic or recessive models. All sera confirmed negative for anti-Trichinella spp. IgG. The study exhaustively covered almost all marine fish processing workers in Croatia, reflecting real-time Anisakis sensitization status within the industry, already under the influence of wide array of allergens.

Anisakiasis is a human disease caused by ingestion of live Anisakis spp. larvae by raw seafood. Fish processing and aquaculture workers (approximately 60 million people world-wide) are at occupational risk of becoming sensitized to Anisakis. This is the first study systematically evaluating the risk of Anisakis-sensitization in Croatian fish-processing workers and potential genetic susceptibility to anisakiasis in the analysed population. Observed seroprevalence was significantly higher in fish processing workers (1.8%) compared to the controls (0%). Surprisingly, the highest risk associated with Anisakis-sensitization among workers was fishing in their free time, rather than any of attributes related to the occupational exposure. While no association was observed between anti-Anisakis seropositivity and wearing gloves or protective goggles, the majority of workers (92%) wore protective gloves, minimizing the risk for Anisakis sensitization via skin contact. Additionally, seroprevalence to another important food-borne helminth, Trichinella spp. assessed in all Anisakis-positive subjects showed to be negative. Almost all marine fish processing workers in Croatia were part of this research, reflecting real-time Anisakis-sensitization status within the industry. This sets a baseline for the future tracking of sensitization in the sector already under the influence of wide array of allergens.

Asthma and Food Allergy: Which Risks?

Over the past few decades, an increase in the prevalence of asthma and food allergy has been observed in the pediatric population. In infants, food sensitization, particularly to egg, has increased the risk of developing allergic asthma. This is even more likely if sensitization to food allergens occurs early within the first few years of life. It is indeed known that both diseases may be present simultaneously in the pediatric population, but coexistence may negatively influence the severity of both conditions by increasing the risk of life-threatening asthmatic episodes as well as food-related anaphylaxis. Therefore, an accurate clinical and phenotype characterization of this high-risk group of children with both asthma and food allergy and a more aggressive management might lead to reducing related morbidity and mortality. The aim of this review is to provide an updated overview on the close link between food allergy and asthma and their negative mutual influence.

Characterization of a subgroup of non-type 2 asthma with cow's milk hypersensitivity in young subjects

Background

Asthma with atopy is often characterized by type 2 inflammation but less progress has been made in defining non-type 2 asthma. We have previously identified a subgroup of young non-atopic asthmatics with perceived food hypersensitivity and poor asthma control.

Objective

Our aim was to further characterize this subgroup of non-type 2 asthmatics, including the use of a broad panel of inflammation-related proteins.

Methods

Sex- and age-matched subjects (10–35 years old) were divided into three groups with regard to history of asthma and atopy: non-atopic asthmatics with perceived cow’s milk hypersensitivity but with IgE antibodies < 0.35 kU_A/L (NAA; n = 24), non-atopic controls with IgE < 0.35 kU_A/L (NAC; n = 24), and atopic asthmatics with IgE ≥ 0.35 kU_A/L (AA; n = 29). Serum or plasma were analysed using the multi-allergen tests Phadiatop and fx5 (ImmunoCAP), a multiplex immunoassay comprising 92 inflammation-related proteins (Proseek Inflammation), and an ELISA for human neutrophil lipocalin (S-HNL). Fraction of exhaled nitric oxide (FeNO), blood eosinophil (B-Eos) count, C-reactive protein (CRP), airway responsiveness to methacholine (PD₂₀), and asthma-related quality of life (mAQLQ) were also measured.

Results

NAA had lower FeNO (p < 0.001) and B-Eos count (p < 0.001), but scored worse on mAQLQ (p = 0.045) compared with AA. NAA displayed higher levels of matrix metalloproteinase-1 (MMP-1) compared with both NAC (p = 0.011) and AA (p = 0.001), and lower PD₂₀ compared with NAC (p < 0.001). In NAA, S-HNL correlated negatively with PD₂₀ (rho = − 0.048, p < 0.05) and CRP correlated negatively with mAQLQ (rho = − 0.439, p < 0.05).

Conclusion

In a subgroup of non-atopic young asthmatics with perceived cow’s milk hypersensitivity we observed poor asthma-related quality of life, airway hyperresponsiveness, and clinically relevant non-type 2 inflammation. MMP-1 was elevated in this group, which deserves further studies.

Electronic supplementary material

The online version of this article (10.1186/s13601-019-0250-2) contains supplementary material, which is available to authorized users.

Modulation of the airway smooth muscle phenotype in a murine asthma model and effects of nuclear factor-κB inhibition

Objective: Phenotype modulation of airway smooth muscle (ASM) is a unique characteristic of asthma and is considered to regulate airway remodeling, airway hyperresponsiveness (AHR) and inflammation. The nuclear factor-κB (NF-κB) signaling pathway plays a crucial role in phenotypic modulation. Thus, models of acute and chronic asthma were established and pyrrolidine dithiocarbamate (PDTC), an NF-κB inhibitor was delivered by intraperitoneal injection. Methods: The Penh value was measured using the BUXCO WBP system. Lung tissues were subjected to histologic analysis. Phenotypic markers of ASM and COL1A1 mRNA levels were measured by RT-PCR. Expression levels of phosphorylated p65 (pP65) and α-SMA were detected by Western blot. Serum cytokine levels were quantified by RayBiotech ELISA array. Results: PDTC intervention decreased the Penh values in both the acute and chronic models. The ASM area and the airway collagen area were decreased in the PDTC intervention group. A decrease in phenotypic markers were detected in both the acute and chronic models in time-dependent manner, and PDTC intervention partially reversed the phenotypic modulation. The effect of PDTC intervention on systemic inflammation was also verified. Conclusion: These results revealed the existence of a dynamic ASM phenotype modulation procedure in asthma development and that targeting NF-κB by PDTC was effective to mitigate ASM phenotype modulation and major asthmatic pathological features.

Grass-Allergic Children Frequently Show Asymptomatic Low-Level IgE Co-Sensitization and Cross-Reactivity to Wheat

BACKGROUND

Specific immunoglobulin E (IgE) sensitization to wheat is more common than a doctor's confirmed wheat allergy and is also frequently observed in grass pollen-allergic patients (pollinosis patients). Thus, the objective of this study was to investigate the level and feature of serological IgE cross-reactivity between grass pollen and wheat in a cohort of pollinosis subjects with no diagnosis of wheat allergy.

METHODS

Seventy-two children, aged 5-17 years, with a doctor's diagnosis of pollinosis, IgE towards grass pollen, and currently eating wheat were recruited. Serum samples were analyzed for IgE against wheat, timothy grass/wheat-specific allergen components, Pru p 3, and cross-reactive carbohydrate determinants (CCD) and specific IgE-binding inhibition experiments were performed.

RESULTS

Sixty percent of the grass pollen subjects were sensitized to wheat with a median of 0.5 kUA/L. Wheat-sensitized subjects were more often sensitized to the two allergens, Phl p 12 and CCD, known to be cross-reactive between grass and wheat. Sensitizations to seven wheat-specific allergens derived from the gluten fraction were, with the exception of one individual, only found in wheat-sensitized subjects. These subjects also more often reported current and past history of allergy to staple foods (milk, egg, wheat, soy, and fish).

CONCLUSION

Wheat sensitization caused by cross-reactivity but also by sensitization to wheat-specific allergens was common in the grass-allergic children and also associated with allergy to staple foods other than wheat. The results indicate the presence of a subgroup of pollinosis patients with simultaneous sensitization to wheat and food allergy not only caused by cross-reactions.

IgE sensitization to food allergens and airborne allergens in relation to biomarkers of type 2 inflammation in asthma

BACKGROUND

We have recently reported that sensitization to food allergens and sensitization to airborne allergens had independent associations with increased fraction of exhaled nitric oxide (FeNO) and blood eosinophils in middle-aged adults and in young subjects with asthma.

OBJECTIVE

To investigate the relation between IgE sensitization and several type 2 inflammation biomarkers in adult asthmatics.

METHODS

FeNO, urinary eosinophil-derived neurotoxin (U-EDN), serum eosinophil cationic protein (S-ECP) and periostin were measured in 396 asthmatics, aged 17-76 years, from the Swedish GA2LEN study. Sensitization to airborne allergens was examined with skin prick tests (≥3 mm wheal) and sensitization to food allergens with measurement of specific IgE (≥0.35 kU/L).

RESULTS

Asthmatics sensitized to food allergens had higher FeNO, 22.3 ppb (18.6, 26.7) vs 16.1 ppb (14.2, 18.2) (P = .005), S-ECP, 17.7 mg/L (14.8, 21.1) vs 12.8 mg/L (10.9, 14.9) (P = .01), and periostin, 73.7 (67.5, 80.3) ng/mL vs 59.9 (55.8, 64.2) ng/mL (P = .003), than non-sensitized subjects. Periostin levels in this group were also significantly higher than in the group sensitized only to airborne allergens (P = .01). Sensitization to food allergens related independently to FeNO (P = .02), S-ECP (P = .006) and periostin (P = .004), whereas sensitization only to airborne allergens related only to FeNO (P = .02) after adjustments for age, sex, height, weight and smoking history. FeNO correlated weakly with S-ECP (r = .17, P < .001), periostin (r = .19, P < .001) and U-EDN (0.16, P < .001). S-ECP also correlated weakly with U-EDN (r = .12, P = .02). None of the correlations between the remaining pairs of markers of type 2 inflammation were significant.

CONCLUSIONS & CLINICAL RELEVANCE

Sensitization to food allergens related to several local and systemic type 2 inflammation markers, such as FeNO, S-ECP and periostin. Assessing the profile of allergic sensitization, including to food allergens, might improve the understanding and interpretation of inflammatory markers and potentially improve asthma management.

Sensitization to minor cat allergen components is associated with type-2 biomarkers in young asthmatics

BACKGROUND

Cat allergy is a major trigger of asthma world-wide. Molecular patterns of cat sensitization vary between individuals, but their relationship to inflammation in asthmatics has not been extensively studied.

OBJECTIVE

To investigate the prevalence and levels of IgE antibodies against different cat allergen components and their relationship to type-2 inflammation and total IgE among young asthmatic subjects sensitized to furry animals.

METHODS

Patients with asthma (age 10-35 years; n = 266) and IgE sensitization to cat, dog or horse extract (ImmunoCAP), were analysed for IgE to the cat allergen components Fel d 1 (secretoglobin), Fel d 2 (serum albumin), Fel d 4 and Fel d 7 (lipocalins). Independent associations between IgE-antibody concentrations, and fraction of exhaled nitric oxide (FeNO), blood eosinophil (B-Eos) count, and total IgE were analysed by multiple linear regression after adjustment for possible confounders.

RESULTS

The level of IgE against Fel d 2 was independently related to FeNO (P = .012) and total IgE (P < .001), and IgE against Fel d 4 associated with Β-Eos count (P = .009) and total IgE (P < .001). IgE antibodies against Fel d 1 or cat extract did not independently relate to these inflammatory markers (P = .23-.51).

CONCLUSIONS

Levels of IgE to lipocalin (Fel d 4) and serum albumin (Fel d 2), but not to secretoglobin (Fel d 1) or cat extract, were independently associated with type-2 biomarkers and total IgE in young asthmatics.

CLINICAL RELEVANCE

We suggest that measurement of IgE to minor cat allergen components may be useful when investigating asthma morbidity in cat allergic subjects.

The absence of serum IgE antibodies indicates non-type 2 disease in young asthmatics

BACKGROUND

Atopic asthma is associated with elevated type-2 biomarkers such as fraction of exhaled nitric oxide (FeNO) and blood eosinophil (B-Eos) count. However, increased type 2 markers have also been reported in traditionally defined non-atopic asthma.

OBJECTIVE

To determine a clinically useful level of IgE sensitization for ruling out type 2 asthma.

METHODS

Asthmatics (N = 408; age 10-35 years) were analysed using the multi-allergen tests Phadiatop and fx5 (ImmunoCAP). Subjects were grouped based on IgE-antibody concentrations: ≥0.35 kU_A /L for at least one test (n = 326) or <0.35 kU_A /L for both tests (n = 82). Τhe latter group was subsequently divided into 2 groups: IgE 0.10-0.34 kU_A /L (n = 34) and IgE < 0.10 kU_A /L (n = 48). The relationships between type 2 biomarkers, and inadequate asthma control (ACT < 20), reduced lung function (FEV₁  < 80%), recent asthma attacks and airway hyperresponsiveness (AHR) to methacholine were determined.

RESULTS

In univariate analyses, at least one type 2 marker related to each asthma outcome in subjects with IgE ≥0.35 kU_A /L. In subjects with IgE 0.10-0.34 kU_A /L, elevated FeNO related to reduced lung function (P = .008) and B-Eos to AHR (P = .03). No associations were found in subjects with IgE < 0.10 kU_A /L. In multivariate analysis, a relationship between FeNO and reduced lung function remained in subjects with IgE < 0.35 kU_A /L (P = .03).

CONCLUSION AND CLINICAL RELEVANCE

Clinically relevant elevation of type 2 biomarkers was seen in young asthmatics with IgE antibodies <0.35 kU_A /L, but not those with IgE < 0.10 kU_A /L. It seems possible to define non-type 2 asthma through sensitive IgE-antibody measurement.

Allergen extract vs. component sensitization and airway inflammation, responsiveness and new-onset respiratory disease

BACKGROUND

The absence of IgE sensitization to allergen components in the presence of sensitization to the corresponding extract has been reported, but its clinical importance has not been studied.

OBJECTIVE

To evaluate the clinical significance of IgE sensitization to three aeroallergen extracts and the corresponding components in relation to the development of respiratory disease.

METHODS

A total of 467 adults participated in the European Community Respiratory Health Survey (ECRHS) II and 302 in ECRHS III, 12 years later. IgE sensitization to allergen extract and components, exhaled nitric oxide (FeNO) and bronchial responsiveness to methacholine were measured in ECRHS II. Rhinitis and asthma symptoms were questionnaire-assessed in both ECRHS II and III.

RESULTS

A good overall correlation was found between IgE sensitization to extract and components for cat (r = 0.83), timothy (r = 0.96) and birch (r = 0.95). However, a substantial proportion of subjects tested IgE positive for cat and timothy allergen extracts but negative for the corresponding components (48% and 21%, respectively). Subjects sensitized to both cat extract and components had higher FeNO (P = 0.008) and more bronchial responsiveness (P = 0.002) than subjects sensitized only to the extract. Further, subjects sensitized to cat components were more likely to develop asthma (P = 0.005) and rhinitis (P = 0.007) than subjects sensitized only to cat extract.

CONCLUSION

Measurement of IgE sensitization to cat allergen components would seem to have a higher clinical value than extract-based measurement, as it related better to airway inflammation and responsiveness and had a higher prognostic value for the development of asthma and rhinitis over a 12-year period.

Overall and peripheral lung function assessment by spirometry and forced oscillation technique in relation to asthma diagnosis and control

BACKGROUND

Classic spirometry is effort dependent and of limited value in assessing small airways. Peripheral airway involvement, and relation to poor control, in asthma, has been highlighted recently. Forced oscillation technique (FOT) offers an effort-independent assessment of overall and peripheral lung mechanics. We studied the association between lung function variables, obtained either by spirometry or multifrequency (5, 11 and 19 Hz) FOT, and asthma diagnosis and control.

METHODS

Spirometry measures, resistance at 5 (R5) and 19 Hz (R19), reactance at 5 Hz (X5), resonant frequency (f_res ), resistance difference between 5-19 Hz (R5-R19) and Asthma Control Test scores were determined in 234 asthmatic and 60 healthy subjects (aged 13-39 years). We used standardized lung function variables in logistic regression analyses, unadjusted and adjusted for age, height, gender and weight.

RESULTS

Lower FEV₁ /FVC (OR [95% CI] 0.47 [0.32, 0.69]) and FEF₅₀ (0.62 [0.46, 0.85]) per standard deviation increase, and higher R5 (3.31 [1.95, 5.62]) and R19 (2.54 [1.65, 3.91]) were associated with asthma diagnosis. Independent predictive effects of FEV₁ /FVC and R5 or R19, respectively, were found for asthma diagnosis. Lower FEV₁ /FVC and altered peripheral FOT measures (X5, f_res and R5-R19) were associated with uncontrolled asthma (P-values < .05).

CONCLUSIONS

Resistance FOT measures were equally informative as spirometry, related to asthma diagnosis, and, furthermore, offered additive information to FEV₁ /FVC, supporting a complementary role for FOT. Asthma control was related to FOT measures of peripheral airways, suggesting a potential use in identifying such involvement. Further studies are needed to determine a clinical value and relevant reference values in children, for the multifrequency FOT measurements.

New Perspectives on the Diagnosis of Allergy to Anisakis spp

PURPOSE OF REVIEW

To compare the prevalence of sensitization in different countries based on specific IgE values and to evaluate the use of isolated native or recombinant allergens for diagnosis.

RECENT FINDINGS

Isolated allergens help in the diagnosis of truly sensitized patients avoiding false positives due to cross-reactions. Their use is therefore highly recommended, especially when used as a combination of several relevant allergens. The use of purified allergens allows an accurate diagnosis and this has led to three important findings: (1) in addition to the digestive route of sensitization, occupational and non-digestive exposure seems to be clinically relevant. (2) The parasite appears as an important agent for chronic urticaria. And (3) in endemic countries, the amount of highly sensitized subjects in the general population could be as high as 7%. Adequate information to asymptomatic patients on fish consumption habits would avoid new contacts with parasite allergens and decrease their specific IgE levels and consequently the appearance of acute or chronic episodes induced by the parasite.

Evaluation of the association between sensitization to common inhalant fungi and poor asthma control

BACKGROUND

Fungi are well-known airborne allergens that are predisposing environmental factors to asthma. Few comparative studies have evaluated sensitization to common inhalant fungi in relation to poor asthma control in patients with asthma.

OBJECTIVE

To evaluate the association between sensitization to individual fungi and asthma control and elucidate the characteristics of patients with poorly controlled asthma sensitized to fungi.

METHODS

This cross-sectional study was performed at Showa University Hospital between September 2014 and December 2014. The specific IgE levels for several major aeroallergens, including house dust mites, Japanese cedar, various types of pollen, furry animals, or insects, were measured with a fluorescent enzyme immunoassay in 160 patients with adult asthma.

RESULTS

Fungal sensitization was predominant in men with asthma, and it was associated with poor asthma control. Sensitization to house dust mites, Japanese cedar, pollen, furry animals, or insects was not associated with poor asthma control. Logistic regression analyses revealed that patients sensitized to Aspergillus and Penicillium had a significantly increased risk of poor asthma control. More Penicillium IgE-positive patients were men and pet owners compared with Penicillium IgE-negative patients; in addition, Penicillium IgE-positive patients had higher total IgE levels. The Asthma Control Test level was significantly higher in Penicillium IgE-positive patients than in Penicillium IgE-negative patients. However, there were no differences in fractional exhaled nitric oxide, forced vital capacity, and forced expiratory volume in 1 second. Finally, sensitization to Aspergillus, Cladosporium, and Trichophyton were positively correlated with sensitization to Penicillium.

CONCLUSION

Sensitization to fungi is predominant in men, and it is associated with poor asthma control. In particular, sensitization to Penicillium and Aspergillus is a risk factor for asthma severity. These results have potential relevance in asthma management.

Exhaled and nasal nitric oxide in relation to lung function, blood cell counts and disease characteristics in cystic fibrosis

BACKGROUND

Patients with cystic fibrosis (CF) have similar or lower exhaled nitric oxide (FeNO) and lower nasal nitric oxide (nNO) levels than controls. There are divergent results on alveolar NO (Calv_NO) concentrations in relation to CF. There are inconsistent results on correlation between different nitric oxide parameters and lung function and inflammation in CF.

AIM

To compare FeNO, Calv_NO and nNO levels between subjects with CF, asthma and healthy controls and to study whether these parameters are related to lung function, blood cell counts or clinical characteristics in CF patients.

MATERIAL AND METHODS

Measurements of FeNO at multiple exhalation flow rates, nNO and spirometry were done in 38 patients (18 adults) with CF. Blood cell counts and CF clinical characteristics were recorded. Thirty-eight healthy controls and 38 asthma patients, gender- and age-matched, were included as reference groups.

RESULTS

FeNO levels were lower in CF patients (7.2 [4.7-11.2] ppb) than in healthy controls (11.4 [8.3-14.6] ppb) and asthma patients (14.7 [8.7-24.7] ppb) (both p < 0.005). These differences were consistent in adults. No difference in Calv_NO was seen between the groups. nNO levels in CF patients (319 [193-447] ppb) were lower than in healthy controls (797 [664-984] ppb) and asthma patients (780 [619-961] ppb) (both p < 0.001). FeNO positively related to FEV₁ (rho = 0.51, p = 0.001) in CF patients and this was consistent in both adults and children. A negative correlation was found between FeNO and blood neutrophil counts (rho = -0.37, p = 0.03) in CF patients.

CONCLUSION

CF patients have lower FeNO and nNO and similar Calv_NO levels as healthy controls and asthma patients. Lower FeNO related to lower lung function in both adults and children with CF. Furthermore, in CF, lower FeNO also related to higher blood neutrophil counts.

Recent advances in component resolved diagnosis in food allergy

Due to the high prevalence of food allergic diseases globally there are increasing demands in clinical practice for managing IgE-mediated conditions. During the last decade, component resolved diagnostics has been introduced into the field of clinical allergology, providing information that cannot be obtained from extract-based tests. Component resolved data facilitate more precise diagnosis of allergic diseases and identify sensitizations attributable to cross-reactivity. Furthermore it assists risk assessment in clinical practice as sensitization to some allergenic molecules is related to persistence of clinical symptoms and systemic rather than local reactions. The information may also aid the clinician in prescription of oral immunotherapy (OIT) in patients with severe symptoms, and in giving advice on food allergen avoidance or on the need to perform food challenges. The use of allergen components is rapidly evolving and increases our possibility to treat food allergic patients with a more individual approach. Using molecular allergology, we can already now better diagnose, prognose and grade the food allergy. In summary, daily routine molecular allergy diagnostics offers a number of benefits that give us a higher diagnostic precision and allow for better management of the patient.

The impact of food allergens on airway responsiveness in schoolchildren with asthma: A DBPCFC study

BACKGROUND AND OBJECTIVE

Despite the growing evidence of a possible link between asthma and food allergy (FA), so far, the involvement of food in inducing respiratory symptoms has not been fully evaluated. The objective of this study was to evaluate the impact of food allergens on respiratory symptoms and bronchial reactivity (BHR) in schoolchildren with asthma.

METHODS

The initial study group consisted of 362 children with asthma. In the end, 22 children with concomitant FA, and 18 without FA, were selected to participate in the study. Spirometry and Methacholine Inhalation Challenge (MIC) were conducted prior to and after the completion of a double blind placebo control food challenge (DBPCFC).

RESULTS

The food-induced asthmatic reactions were observed in nine (2.5%) out of all 362 children with asthma. Mean FEV1 prior to and after allergen or placebo challenge did not differ between the groups studied. Increase of BHR after DBPCFC was seen in 17 (4.7%) children with asthma. The mean PC20 value in children with FA was 1.41 ± 1.12 mg/ml prior to the allergen challenge and 0.86 ± 0.71 mg/ml (P = 0.002) after the test, whereas these values were 1.93 ± 1.68 mg/ml and 2.02 ± 1.75 mg/ml, respectively, in children without FA (P > 0.05). Significant differences were noted after the allergen provocation in children with FA as compared to children without FA (P = 0.007).

CONCLUSIONS

Although food allergens are a rare trigger of food-induced asthmatic reactions in schoolchildren with asthma, they could enhance BHR, despite a lack of evident clinical respiratory signs and decreased in FEV1 values after food challenge. Pediatr Pulmonol. 2016;51:787-795. © 2016 Wiley Periodicals, Inc.

IgE mediated sensitisation to aeroallergens in an asthmatic cohort: relationship with inflammatory phenotypes and disease severity

BACKGROUND

Atopy is known to play an important role in the asthmatic disease. The main objective of this study was to evaluate the frequency of sensitisation to common aeroallergens in a cohort of asthmatics with different inflammatory phenotypes and disease severity.

METHODS

We have conducted a retrospective cross-sectional study including 772 asthmatics recruited between 2003 and 2014 in our Asthma Clinic. The patients were defined as asthmatics on the basis of respiratory symptoms together with a positive methacholine test (PC20M) < 16 mg/ml and/or a reversibility to short-acting β2-agonists (salbutamol) ≥ 12% and 200 ml. Sensitisation to house dust mites, grass and birch pollens, cats, dogs and moulds was assessed by RAST and a specific immunoglobulin E (IgE) > 0.35 kU/l was considered as significant. Inflammatory phenotypes were subdivided between pauci-granulocytic (n = 309) (40%), eosinophilic (n = 311) (40%), neutrophilic (N = 134) (17%) and mixed-granulocytic (N = 18) (3%) asthmatics. Severe asthmatics (n = 118) were defined according to the American Thoracic Society (ATS 2000) criteria and compared with mild-to-moderate asthmatics (N = 654).

RESULTS

The eosinophilic phenotype was associated with higher levels of total serum IgE compared with neutrophilic and pauci-granulocytic asthma (p < 0.001 for both). Sensitisation rate to dogs and cats was higher in eosinophilic asthmatics (31% and 37%, respectively, p < 0.01 both) compared with neutrophilic (18% and 23% respectively) and pauci-granulocytic asthmatics (20% and 24%, respectively), while sensitisation rate to house dust mites and moulds were rather similar between the groups (ranging from 33% to 40% and from 10% to 16%, respectively). Severe asthmatics had slightly increased total serum IgE compared with mild-to-moderate asthmatics (p < 0.05) without any difference in the sensitisation rate to common aeroallergens.

CONCLUSION

Eosinophilic asthma exhibits higher total serum IgE and sensitisation rate towards animal dander while clinical severity, though also associated with higher total IgE, did not preferentially relate to any type of common aeroallergens.

Simultaneously increased fraction of exhaled nitric oxide levels and blood eosinophil counts relate to increased asthma morbidity

BACKGROUND

We have previously described that fraction of exhaled nitric oxide (Feno) levels and blood eosinophil counts offer additive information in relation to asthma and asthma exacerbations when analyzing data from a large population study.

OBJECTIVE

We sought to investigate increased Feno levels and blood eosinophil counts in relation to lung function, bronchial hyperresponsiveness (BHR), and asthma control in a cohort of young asthmatic patients.

METHODS

Measurements of Feno levels and blood eosinophil counts were available in 406 subjects (208 women) aged 10 to 35 years. Asthma control was assessed through the Asthma Control Test. Moderate-to-severe BHR was defined as a cumulative dose of methacholine of less than 0.3 mg causing an FEV₁ decrease of 20%.

RESULTS

Subjects with simultaneously increased Feno levels (≥20-25 ppb) and blood eosinophil counts (≥0.3 × 10⁹/L) had a higher prevalence of uncontrolled asthma (Asthma Control Test score, <20) than subjects with singly increased blood eosinophil counts (40.5% vs 21.1%, P = .01). This difference remained significant (P = .006), and a significant difference was also found between subjects with both increased Feno levels and blood eosinophil counts and subjects with normal Feno levels and blood eosinophil counts (P = .02) after adjusting for confounders. Having increased Feno levels and blood eosinophil counts related to a higher prevalence of moderate-to-severe BHR than having normal Feno levels and blood eosinophil counts or singly increased Feno levels or blood eosinophil counts (85.7% vs 35.8% or 63.3% or 60%, P < .05 all comparisons).

CONCLUSION

We have shown that simultaneously increased local (Feno) and systemic (blood eosinophil) markers of type 2 inflammation related to a higher likelihood of BHR and uncontrolled asthma in a large cohort of young asthmatic patients.

Presence of rhinovirus in the respiratory tract of adolescents and young adults with asthma without symptoms of infection

Background

Viral respiratory infections have been associated with up to 80% of wheezing episodes and asthma exacerbations. However, studies on the role of these viruses in asthmatic patients in the interval between exacerbations are sparse. This study aimed to determine the presence of respiratory viruses, without symptoms of infection, in the airways of young asthmatics as compared to healthy controls.

Material and Methods

Patients 10–35 years of age with stable asthma and a group of healthy controls were analyzed regarding the presence of RNA from common respiratory viruses in nasopharyngeal aspirates by PCR. Self-reported asthma control and quality of life, fraction of exhaled nitric oxide (FeNO), spirometry, and bronchial responsiveness to methacholine were recorded. Blood samples were collected to assess IgE sensitisation and eosinophil cationic protein (ECP) levels.

Results

In 354 patients with asthma and 108 healthy controls, human rhinovirus (HRV) was the only virus detected (4.5% of asthmatics vs. 0.9% of controls; p = 0.08). HRV⁺ asthma patients had a higher degree of aeroallergen IgE sensitisation (median 37.7 vs. 10.4 kU_A/L, p = 0.04), and a tendency for higher levels of serum ECP (median 17.2 vs. 12.6 μg/L, p = 0.07), as compared to their HRV⁻ counterparts.

Conclusions

Absence of symptoms of respiratory tract infection notwithstanding, HRV seems to be more prevalent in the airways of adolescents and young adults with asthma and a high degree of aeroallergen IgE sensitisation than in controls. The presence of HRV seems also to be related to systemic eosinophilic inflammation despite ongoing treatment with inhaled corticosteroids.

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Cross-sectional study on adolescents and young adults with asthma and healthy controls.

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Common respiratory viruses examined in nasopharyngeal aspirates by PCR.

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Only rhinovirus detected in subjects without symptoms of respiratory tract infection.

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Prevalence of rhinovirus tended to be higher in asthmatics compared to controls.

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Presence of rhinovirus associated with high degree of aeroallergen IgE sensitisation.

Parallel reductions of IgE and exhaled nitric oxide after optimized anti-inflammatory asthma treatment

Immunoglobulin E (IgE) is crucial for the development of airway inflammation in atopic asthma, and inhibition of IgE using monoclonal antibodies is now part of asthma therapy. However, the impact of ordinary anti-inflammatory treatment on IgE is unclear. The aim of this study was to investigate if optimization of treatment with inhaled corticosteroid (ICS) and leukotriene-receptor antagonist (LTRA) according to symptoms or exhaled nitric oxide (F_ENO) levels over a one-year period affects IgE concentrations. Altogether, 158 relatively well-controlled but multi-sensitized asthmatics (age 18-65 years), with ongoing ICS treatment at baseline, were included in this post hoc analysis of data from a randomized, controlled trial on F_ENO-guided asthma therapy. Asthma control and quality of life (Juniper ACQ and mAQLQ), F_ENO, and serum IgE were measured at baseline and after one year. Concentrations of IgE antibodies to six common perennial aeroallergens were summed up (perennial IgE). We found that perennial and total IgE decreased by 10.2% and 16.0% (P < .001 both comparisons). This was not related to allergen exposure, whereas the total use of ICS and LTRA during the year correlated with the reduction in perennial IgE (P = .030 and P = .013). The decrease in perennial and total IgE correlated significantly with the reduction in F_ENO (P < .003 and P < .001), and with improvements in ACQ and mAQLQ scores (P < 0.05, all comparisons). We conclude that one year of optimization of treatment with ICS and LTRA in patients with persistent atopic asthma resulted in significant decreases in total IgE and IgE antibodies; these decreases correlated with a reduction in F_ENO and improvements in asthma control and quality of life. Thus, IgE is reduced by ordinary asthma controller medications and the effect on IgE seems to be clinically important.

Asthma in the elderly: the effect of choline supplementation

Background

Asthma in the elderly is poorly understood as very few studies have included these patients. DNA methylation can affect the expression of asthma susceptibility genes. Methyl groups can be produced through a choline dependent pathway. Asthmatics have decreased serum choline. We studied the effect of choline supplementation in elderly asthmatics and associations between different parameters at baseline.

Methods

This is a double-blind, placebo-controlled, cross-over study. Thirty asthmatics 65 years old and older were evaluated at baseline and 3, 6, 9, and 12 weeks later. They randomly received choline bitartrate 310 mg and placebo capsules twice daily for 6 weeks.

Results

Ninety percent of the study subjects were atopic and 97 % of them were using inhaled corticosteroids. Choline supplementation did not affect ACT (asthma control test), spirometric values, eosinophil counts or total serum IgE vs. placebo (p > 0.86 for all comparisons). In subjects with lower ACT (≤20), lower FEV1 % (<60 %), or higher eosinophil counts (≥0.6), there was similarly no difference between choline and placebo (p > 0.63). We found no significant association between eosinophil counts and IgE and the other parameters at baseline including in subjects with lower ACT or on higher inhaled steroid doses (p > 0.09). Asthmatic women had lower baseline ACT scores compared to men (p = 0.02).

Conclusions

In this study of elderly asthmatics, choline supplementation for 6 weeks did not affect ACT scores, spirometric values, peripheral blood eosinophils, or total serum IgE. These results will require confirmation in larger and longer studies.

Trial registration ClinicalTrials.gov NCT02371993

Effects of poor asthma control, insomnia, anxiety and depression on quality of life in young asthmatics

OBJECTIVE

Asthma-related quality of life has previously been shown to be associated with asthma control. The aims of the present study were to further analyze this correlation, identify other variables with impact on asthma-related quality of life and investigate the covariance among these variables.

METHODS

Information was retrieved from a cohort of 369 patients, aged 12-35, with physician-diagnosed asthma requiring anti-inflammatory treatment for at least 3 months per year. Questionnaire data [including the mini-Asthma Quality of Life Questionnaire (mAQLQ), asthma control test (ACT) and Hospital Anxiety and Depression Scale (HADS)], quality of sleep, lung function data and blood samples were analyzed. Linear regression models with the mAQLQ score as the dependent scalar variable were calculated.

RESULTS

ACT was the single variable that had the highest explanatory value for the mAQLQ score (51.5%). High explanatory power was also observed for anxiety and depression (17.0%) and insomnia (14.1%). The population was divided into groups depending on the presence of anxiety and depression, uncontrolled asthma and insomnia. The group that reported none of these conditions had the highest mean mAQLQ score (6.3 units), whereas the group reporting all of these conditions had the lowest mAQLQ score (3.8 units).

CONCLUSIONS

The ACT score was the single most important variable in predicting asthma-related quality of life. Combining the ACT score with the data on insomnia, anxiety and depression showed considerable additive effects of the conditions. Hence, we recommend the routine use of the ACT and careful attention to symptoms of insomnia, anxiety or depression in the clinical evaluation of asthma-related quality of life.

New data analysis in a population study raises the hypothesis that particle size contributes to the pro-asthmatic potential of small pet animal allergens

BACKGROUND

The size of inhaled particles influences where they deposit and theoretically should be important for the development of airway inflammation and responsiveness. Our aim was to assess if sensitization to smaller-sized aeroallergens relates to higher prevalence of treated asthma, increased airway responsiveness, and airway and systemic inflammation.

METHODS

Molecular-based IgE antibody determination was done in 467 subjects. Sensitized subjects were grouped based on the particle size of the aeroallergen: (1) Large particles only (mainly pollen); (2) Medium-sized particles (sensitized to mainly mite and mold and possibly to large particles); and 3) Small particles (sensitized to pet allergens and possibly to medium- and/or large-sized particles). Airway responsiveness to methacholine, exhaled nitric oxide (FENO), and serum eosinophil cationic protein (S-ECP) were measured. Asthma and rhinitis were questionnaire-assessed.

RESULTS

Subjects sensitized to small particles had higher prevalence of treated asthma (35% versus 10%, P < 0.001), higher FENO50 (32 versus 17 ppb, P < 0.001), higher S-ECP (10 versus 7.5 ng/mL, P = 0.04), and increased bronchial responsiveness (dose-response slope, 5.6 versus 7.5, P < 0.001) compared with non-atopics. This was consistent after adjusting for potential confounders. Sensitization to only large or to medium and possibly also large aeroallergen particles was not related to any of these outcomes after adjustments.

CONCLUSIONS

Sensitization to smaller particles was associated with a higher prevalence of asthma under treatment, higher airway responsiveness, and airway and systemic inflammation. Mapping of IgE sensitization to small particles might help to detect subjects having increased airway and systemic inflammation and bronchial responsiveness, indicating increased risk of developing asthma.

Asthma and Food Allergy in Children: Is There a Connection or Interaction?

This review explores the relationship between food allergy and asthma. They can share the same risk factors, such as parental allergy, atopic eczema, and allergen sensitization, and they often coincide in the same child. Coexistence may negatively influence the severity of both conditions. However, it remains to be determined whether food allergy may directly affect asthma control. An early food sensitization in the first year of life can predict the onset of asthma. Furthermore, asthmatic symptoms could rarely be caused by ingestion or inhalation of the offending food. Asthma caused by food allergy is severe and may be associated with anaphylactic symptoms. Therefore, an accurate identification of the offending foods is necessary in order to avoid exposure. Patients should be instructed to treat asthmatic symptoms quickly and to use self-injectable epinephrine.

Sensitization pattern to inhalant and food allergens in symptomatic children at first evaluation

Background

Data on specific IgE sensitization prevalence in children with allergy-like symptoms seen in the primary care setting are rare. Early diagnosis of allergic diseases is important to prevent clinical manifestations, exacerbations or expansion of allergic diseases to other organ systems. The present study aims to assess the usefulness of early serological diagnosis in children with common allergic symptoms.

Methods

532 children (<15 years of age), with at least one of ten allergy-like symptoms, from 21 primary care centers in two geographic areas of Italy and Spain were included in the study. Patients were tested with, either Phadiatop® Infant (0–5 years of age) or Phadiatop® and food mix (fx5e) (>5 years of age) to discriminate atopic from non-atopic subjects. A blood sample of atopic subjects was taken for additional 6–26 specific IgE antibody determinations from a predefined panel using the ImmunoCAP^® System.

Results

267 children (50.2 %) were positive in the initial test and were classified as atopic. 14 % were mono-sensitized, 37 % were sensitized to 2–3 allergens and 49 % to more than 3 allergens. The average number of symptoms in the atopic group was 3.3 vs 2.8 in the non-atopic group. The prevalence of sensitization to single allergens was highest for grass and ragweed pollen and house-dust mites (19–28 %). Sensitization to tree allergens was highest for olive tree (16.5 %). Cow’s milk and egg white were the most sensitizing foods (~15 %). Food allergen sensitization predominated in younger children (OR = 2.8) whereas the inverse occurred with inhalant allergens (OR = 2.5 to 5.6). A significant positive correlation between patient age and the number of sensitizations was found.

Conclusions

Specific IgE sensitization in children with allergy-like symptoms is common. Multiple sensitization is predominating. Number of clinical symptoms was higher in the atopic group compared to the non-atopic without a correlation with the number of positive allergens. Age seems to play a crucial role in the development of sensitization with a significant positive correlation between patient age and the number of sensitizations.

Lin- CD34hi CD117int/hi FcεRI+ cells in human blood constitute a rare population of mast cell progenitors

Mast cells are rare tissue-resident immune cells that are involved in allergic reactions, and their numbers are increased in the lungs of asthmatics. Murine lung mast cells arise from committed bone marrow-derived progenitors that enter the blood circulation, migrate through the pulmonary endothelium, and mature in the tissue. In humans, mast cells can be cultured from multipotent CD34(+) progenitor cells. However, a population of distinct precursor cells that give rise to mast cells has remained undiscovered. To our knowledge, this is the first report of human lineage-negative (Lin(-)) CD34(hi) CD117(int/hi) FcεRI(+) progenitor cells, which represented only 0.0053% of the isolated blood cells in healthy individuals. These cells expressed integrin β7 and developed a mast cell-like phenotype, although with a slow cell division capacity in vitro. Isolated Lin(-) CD34(hi) CD117(int/hi) FcεRI(+) blood cells had an immature mast cell-like appearance and expressed high levels of many mast cell-related genes as compared with human blood basophils in whole-transcriptome microarray analyses. Furthermore, serglycin, tryptase, and carboxypeptidase A messenger RNA transcripts were detected by quantitative reverse transcription-polymerase chain reaction. Altogether, we propose that the Lin(-) CD34(hi) CD117(int/hi) FcεRI(+) blood cells are closely related to human tissue mast cells and likely constitute an immediate precursor population, which can give rise to predominantly mast cells. Furthermore, asthmatics with reduced lung function had a higher frequency of Lin(-) CD34(hi) CD117(int/hi) FcεRI(+) blood mast cell progenitors than asthmatics with normal lung function.

High levels of physical activity are associated with poorer asthma control in young females but not in males

BACKGROUND AND OBJECTIVE

Earlier studies on the levels of physical activity in asthma patients compared with controls have yielded varying results. We have previously reported that high versus moderate levels of physical activity were associated with higher prevalence of wheezing, especially in females. Here we studied the levels of physical activity in young patients with asthma and healthy subjects and their effect on asthma control.

METHODS

Four hundred eight physician-diagnosed patients with asthma and 118 controls (10-34 years) answered questions concerning frequency and/or duration of physical activity and undertook the Asthma Control Test (ACT), spirometry, methacholine challenges and exhaled nitric oxide measurements.

RESULTS

Asthma patients were more frequently physically active (P = 0.01) and for longer durations (P = 0.002) than controls. Highly versus moderately physically active patients with asthma had a higher prevalence of not well-controlled asthma (ACT < 20) when physical activity was assessed by frequency (40.6% vs 24.1%, P = 0.001) or duration (39.0% vs 21.7%, P < 0.001). This was only seen in females who had reduced ACT items (P < 0.05). Frequently versus moderately active females had an odds ratio of 4.81 (2.43, 9.51) to have ACT < 20, while no such effect was found in males (OR 1.18 (0.61, 2.30)) and this interaction was statistically significantly associated with gender (P = 0.003). No differences in fraction of exhaled nitric oxide or methacholine reactivity were found between moderately and highly physically active females with asthma.

CONCLUSION

Young asthma patients were more active than controls. High levels of physical activity were associated with poor asthma control as judged by the ACT in females, but not in males, and this appears unrelated to airway inflammation or responsiveness.

A population-based study of animal component sensitization, asthma, and rhinitis in schoolchildren

BACKGROUND

Animal sensitization is a major determinant of asthma in children. Component-resolved studies of unselected pediatric populations are lacking. The aim was to describe sensitization to animal components and the association with asthma and rhinitis in animal-sensitized schoolchildren.

METHODS

A random sample of 696 children (11-12 years) from a Swedish population-based cohort was tested for sensitization to cat, dog, and horse dander using ImmunoCAP. Sera from animal-sensitized children were further analyzed by microarray including three allergen components from cat, four from dog, and two from horse. The parents completed an expanded ISAAC questionnaire.

RESULTS

Of 259 animal-sensitized children (≥0.1 kUA /l), 51% were sensitized to all three, 23% to two, and 25% to one species. Current asthma and asthma symptoms following contact with cats were associated with co-sensitization to Fel d 1 and Fel d 4. This association was seen already at moderate-level sensitization (1-15 ISU) to Fel d 4, at which level most children were sensitized to Fel d 1, as well. In dog-sensitized children, the majority was sensitized to more than one dog component, and co-sensitization to Can f 5 and Can f 1/f 2 conferred the greatest risk for asthma. Sensitization to the highly cross-reactive serum albumins was uncommon and not associated with asthma.

CONCLUSIONS

Among schoolchildren in northern Sweden, where mite allergy is uncommon, furry animals were the primary perennial sensitizers. Asthma was associated with higher levels of component sensitization, and sensitization to more than one component from the same animal conferred the greatest risk.

Prevalence and Clinical Impact of IgE-Mediated Food Allergy in School Children With Asthma: A Double-Blind Placebo-Controlled Food Challenge Study

Purpose

Recent studies indirectly suggest a possible link between food allergy (FA) and asthma. Most of them have evaluated the occurrence of FA in asthmatic children, especially in the first year of life, using questionnaire-based studies or specific IgE (sIgE) assay. The aim of this study was to evaluate the prevalence and clinical impact of IgE-mediated FA in school children with asthma using a double-blind placebo-controlled food challenge (DBPCFC).

Methods

The study group consisted of school children with atopic asthma who were admitted to the Department of Pediatric Allergology, Gastroenterology and Nutrition, Medical University of Lodz, for the evaluation of food hypersensitivity. The diagnosis of FA was established using questionnaires, sIgE analysis, and the DBPCFC. Asthma severity and asthma control state were also assessed.

Results

A relationship between consumed food and complaints was reported in 180 children (49.7%). Seventy children (19.3%) were sensitized to food allergens. IgE-mediated FA was confirmed in 24 children (6.6%), while 11 children (3%) demonstrated respiratory symptoms. Food-induced asthma exacerbations were observed in 9 patients (2.5%). Statistically significant differences in the prevalence of atopic dermatitis (P<0.002), urticaria (P<0.03), digestive symptoms (P<0.03), rhinitis (P<0.02), sIgE level (P<0.001), positive family history of atopy (P<0.001) and FA in history (P<0.001) were found between asthmatic children with FA and those without. Children with food-induced asthma exacerbations demonstrated significantly greater severity, poorer controls, and worse morbidity compared to those without.

Conclusions

Although food-induced respiratory reactions in children with asthma were rare, they were classified as severe and associated with worse morbidity, greater severity, and poorer control. As the most commonly observed symptoms were coughing and rhinitis, which can be easily misdiagnosed, a proper diagnosis is essential for improving the management of both clinical conditions.

Perceived food hypersensitivity relates to poor asthma control and quality of life in young non-atopic asthmatics

Background

The relationship between perceived food hypersensitivity in asthmatics, food allergen sensitization, asthma control and asthma-related quality of life has not been studied.

Objective

Our aim was to study the prevalence of perceived food hypersensitivity in a cohort of young asthmatics, its relation to food allergen sensitization, and any correlation to asthma control and asthma-related quality of life.

Methods

Perceived food hypersensitivity, as well as IgE sensitization to common food allergens, levels of exhaled nitric oxide (FeNO), and blood eosinophil counts (B-Eos) were assessed in 408 subjects (211 women) with asthma, aged (mean ± SEM) 20.4 ± 0.3 years. Subjects filled out the Asthma Control Test (ACT) and the Mini Asthma Quality of Life Questionnaire (Mini-AQLQ). Inflammation was assessed by means of FeNO and B-Eos.

Results

Fifty-three per cent of subjects reported food hypersensitivity. A corresponding food allergen sensitization was found in 68% of these subjects. Non-atopic subjects with perceived food hypersensitivity (n = 31) had lower ACT (19 (15 - 22) vs. 21 (20 - 23), p < 0.001) and Mini-AQLQ -scores (5.3 (4.3 - 6.1) vs. 6.1 (5.5 - 6.5), p < 0.001) than subjects with no food hypersensitivity (n = 190), despite lower levels of FeNO and B-Eos (p < 0.05).

Conclusions and Clinical Relevance

Food hypersensitivity was commonly reported among young asthmatics. In a majority of cases, a corresponding food allergen sensitization was found. A novel and clinically important finding was that non-atopic subjects with perceived food hypersensitivity were characterized by poorer asthma control and asthma-related quality of life.

House dust mite-specific immunoglobulin E and longitudinal exhaled nitric oxide measurements in children with atopic asthma

Purpose

House dust mite (HDM) has been suggested to be the most important aeroallergen responsible for atopic asthma in Korea. We aimed to investigate that specific IgE antibodies to HDM and other common indoor aeroallergens contribute differently to total serum IgE and show different relationships with longitudinal fractional exhaled nitric oxide (FeNO) measurements in Korean atopic asthmatic patients.

Methods

A total of 193 children aged 8 to 16 years with intermittent or mild persistent atopic asthma were recruited. Sera were assayed for total IgE and specific IgE antibodies to HDM and other common indoor allergens. FeNO was serially measured 10 times or more over 2 years when subjects were not receiving controller medications.

Results

In 152 children who completed the study, IgE antibodies to specific HDM were more prevalent than those to other common indoor aeroallergens. In addition, IgE antibody titers to HDM were the strongest contributor to total IgE increases. Furthermore, only HDM-specific IgE antibody titer significantly correlated with maximum FeNO (r=0.21, P=0.029) and the rate of FeNO higher than 21 parts per billion (ppb) (r=0.30, P=0.002). Eight patients (5%) were found to have maximum FeNO of 21 ppb or less, suggesting the presence of a low FeNO phenotype among atopic asthmatic patients.

Conclusion

The quantity of HDM-specific IgE antibody provides a possible explanation for increases of total IgE and significantly correlates with the amount and frequency of FeNO increases in Korean atopic asthmatic patients.

Alveolar and exhaled NO in relation to asthma characteristics--effects of correction for axial diffusion

BACKGROUND

Inflammation in the small airways might contribute to incomplete asthma disease control despite intensive treatment in some subgroups of patients. Exhaled NO (FeNO) is a marker of inflammation in asthma and the estimated NO contribution from small airways (CalvNO ) is believed to reflect distal inflammation. Recent studies recommend adjustments of CalvNO for trumpet model and axial diffusion (TMAD-adj). This study aimed to investigate the clinical correlates of CalvNO , both TMAD-adjusted and unadjusted.

METHODS

Asthma symptoms, asthma control, lung function, bronchial responsiveness, blood eosinophils, atopy and treatment level were assessed in 410 subjects, aged 10-35 years. Exhaled NO was measured at different flow-rates and CalvNO calculated, with TMAD-adjustment according to Condorelli.

RESULTS

Trumpet model and axial diffusion-adjusted CalvNO was not related to daytime wheeze (P = 0.27), FEF50 (P = 0.23) or bronchial responsiveness (P = 0.52). On the other hand, unadjusted CalvNO was increased in subjects with daytime wheeze (P < 0.001), decreased FEF50 (P = 0.02) and with moderate-to-severe compared to normal bronchial responsiveness (P < 0.001). All these characteristics correlated with increased FeNO (all P < 0.05). Unadjusted CalvNO was positively related to bronchial NO flux (J'awNO ) (r = 0.22, P < 0.001) while TMAD-adjCalvNO was negatively related to J'awNO (r = -0.38, P < 0.001).

CONCLUSIONS

Adjusted CalvNO was not associated with any asthma characteristics studied in this large asthma cohort. However, both FeNO and unadjusted CalvNO related to asthma symptoms, lung function and bronchial responsiveness. We suggest a potential overadjustment by current TMAD-corrections, validated in healthy or unobstructed asthmatics. Further studies assessing axial diffusion in asthmatics with different degrees of airway obstruction and the validity of proposed TMAD-corrections are warranted.