A molecular sensitization map of European children reveals exposome- and climate-dependent sensitization profiles

BACKGROUND

Understanding differences in sensitization profiles at the molecular allergen level is important for diagnosis, personalized treatment and prevention strategies in allergy.

METHODS

Immunoglobulin E (IgE) sensitization profiles were determined in more than 2800 sera from children in nine population-based cohorts in different geographical regions of Europe; north [BAMSE (Sweden), ECA (Norway)], west/central [PIAMA (the Netherlands), BiB (the United Kingdom), GINIplus (Germany)], and south [INMA Sabadell and Gipuzkoa (Spain) and ROBBIC Rome and Bologna (Italy)] using the MeDALL-allergen chip.

RESULTS

Sensitization to grass pollen allergen, Phl p 1, and to major cat allergen, Fel d 1, dominated in most European regions whereas sensitization to house dust mite allergens Der p 1, 2 and 23 varied considerably between regions and were lowest in the north. Less than half of children from Sabadell which has a hot and dry climate were sensitized to respiratory allergens, in particular house dust mite allergens as compared to Gipuzkoa nearby with a more humid climate. Peanut allergen Ara h 1 was the most frequently recognized class 1 food allergen in Northern/Western Europe, while the fruit allergens Pru p 3, Act d 1 and 2 were prominent in Southern and Western/Central Europe. Ves v 5-sensitization dominated in North and West/Central Europe.

CONCLUSION

We show regional, exposome- and climate-dependent differences in molecular IgE-reactivity profiles in Northern, Western/Central and Southern Europe which may form a molecular basis for precision medicine-based approaches for treatment and prevention of allergy.

Detection of IgE Reactivity to a Handful of Allergen Molecules in Early Childhood Predicts Respiratory Allergy in Adolescence

Background

Sensitization in early childhood may precede respiratory allergy in adolescence.

Methods

IgE reactivity against 132 allergen molecules was evaluated using the MeDALL microarray in sera obtained from a random sample of 786 children at the age of 4, 8 and 16 years in a population based birth cohort (BAMSE). Symptoms were analyzed by questionnaire at ages 4, 8 and 16 years. Clinically and independent relevant allergen molecules accounting for ≥ 90% of IgE reactivities in sensitized individuals and at all time-points were identified as risk molecules and used to predict respiratory allergy. The data was replicated in the Manchester Asthma and Allergy Study (MAAS) birth cohort by studying IgE reactivity with the use of a commercial IgE microarray. Sera were obtained from children at the ages of 3, 5, 8 and 11 years (N = 248) and the outcome was studied at 11 years.

Findings

In the BAMSE cohort 4 risk molecules could be identified, i.e.: Ara h 1 (peanut), Bet v 1 (birch), Fel d 1 (cat), Phl p 1 (grass). For MAAS the corresponding number of molecules was 5: Der p 1 (dust mite), Der f 2 (dust mite), Phl p 1 (grass), Phl p 5 (grass), Fel d 1 (cat). In BAMSE, early IgE reactivity to ≥ 3 of 4 allergen molecules at four years predicted incident and persistent asthma and/or rhinitis at 16 years (87% and 95%, respectively). The corresponding proportions in the MAAS cohort at 16 years were 100% and 100%, respectively, for IgE reactivity to ≥ 3 of 5 risk molecules.

Interpretations

IgE reactivity to a few allergen molecules early in life identifies children with a high risk of asthma and/or rhinitis at 16 years. These findings will be of importance for developing preventive strategies for asthma and rhinitis in children.

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IgE reactivity to only few allergen molecules in early childhood predicts respiratory allergy in adolescence

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It may be possible to develop individualized risk prediction charts for allergic respiratory diseases.

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These findings could be targets for novel intervention therapies.

Birth cohorts are essential for understanding the life course of allergy. With a novel approach using a large panel of micro-arrayed allergen molecules from more than forty allergen sources, we identified a strong IgE signature against a handful of allergen molecules at ages 3–5 years that predicted respiratory allergy with > 90% probability up until adolescence in two geographically separate populations. The results suggest generalizability across populations. The findings are of clinical importance for pediatricians or physicians seeing children at a young age, who could perform early allergy diagnosis with the key allergen molecules to initiate preventive measures

Usefulness of recombinant γ-gliadin 1 for identifying patients with celiac disease and monitoring adherence to a gluten-free diet

Background

Celiac disease (CD) is an inflammatory disease of the small intestine caused by an immunologic hypersensitivity reaction to dietary wheat gluten.

Objectives

We sought to clone, express, and perform IgA epitope mapping of a CD-specific wheat antigen and to study its usefulness for identifying patients with CD and monitoring adherence to a gluten-free diet.

Methods

A synthetic gene coding for γ-gliadin 1 (GG1) was expressed in Escherichia coli. Recombinant γ-gliadin 1 (rGG1) was purified and characterized biochemically, structurally, and immunologically by using sera from patients with CD and control subjects. Overlapping GG1 peptides were synthesized for IgA and IgG epitope mapping. GG1 and peptide-specific antibodies were raised for tracing GG1 in cereals and dietary wheat products and to study its resistance to digestion.

Results

rGG1 was expressed and purified. rGG1-based IgA ELISAs performed in populations of patients with CD and control subjects showed a specificity of 92.9%, which was higher than that of gliadin extract (e). Furthermore, it allowed monitoring of adherence to a gluten-free diet in patients. A 26-amino-acid peptide from the proline-glutamine–rich repetitive N-terminal region was identified as the immunodominant IgA epitope. GG1-related antigens were found in rye, barley, and spelt but not in oat, rice, or maize. GG1 was detected in dietary wheat products after baking, and in particular, the major IgA epitope–containing region was resistant against digestion.

Conclusions

rGG1 and its epitope might be useful for identifying patients with CD, monitoring treatment, and studying the pathomechanisms of CD and development of preventive and therapeutic strategies.

The use of the MeDALL-chip to assess IgE sensitization: a new diagnostic tool for allergic disease?

BACKGROUND

Allergic sensitization is frequently present in asthma and rhinitis, but the role of specific immunoglobulin E (s-IgE) is not always clear. Multiple s-IgE analyses may provide insight into this relationship, thus a microarray chip was developed within the EU-funded MeDALL project. The main objective was to evaluate the performance of the MeDALL-chip compared to ImmunoCAP and skin prick test (SPT) in detecting allergic sensitization in children and secondarily to investigate the association to asthma and allergic rhinitis.

METHODS

From the 'Environment and Childhood Asthma Study', 265 children were investigated at 10 and 16 yr of age with clinical examination, interview, SPT, ImmunoCAP, and the MeDALL-chip including 152 allergen components in the analysis.

RESULTS

Allergic sensitization at 10 yr was more frequently detected using the MeDALL-chip (38.1%) compared to the ImmunoCAP (32.8%) (p = 0.034) and SPT (25.5%) (p < 0.001), but no significant difference was seen at 16 yr (MeDALL-chip 49.8%, ImmunoCAP 48.6%, SPT 45.8%). The MeDALL-chip did not differ significantly from the ImmunoCAP or SPT in terms of detecting allergic sensitization in subjects with rhinitis or asthma at 10 or 16 yr.

CONCLUSION

The prevalence of allergic sensitization increased by all three diagnostic tests from 10 to 16 yr was similar by SPT and ImmunoCAP and significantly higher with the MeDALL-chip at 10 yr. All three tests were comparable for identification of allergic sensitization among children with current rhinitis or asthma.

Wheat allergy in children evaluated with challenge and IgE antibodies to wheat components

INTRODUCTION

Wheat sensitization is common but IgE antibodies (IgE-abs) to wheat are not predictive of clinical symptoms in children with suspected wheat allergy. Wheat allergen components other than ω-5 gliadin have not been well studied. Our aim was to characterize the clinical profile and investigate the value of adding measurements of IgE-abs to wheat components in a group of children with a doctor's diagnosed wheat allergy.

METHOD

Sixty-three children with a doctor's diagnosis of wheat allergy confirmed sensitization to wheat and, on a wheat elimination diet, went through oral wheat challenges or had a convincing recent history of wheat allergy. IgE-ab to ω-5 gliadin, low molecular weight glutenin (LMW-glutenin), high molecular weight glutenin (HMW-glutenin) and a native gliadin preparation containing α-, β-, γ-, and ω-gliadin (gliadin) were analyzed.

RESULTS

Twenty-six children were positive in challenge, while six children were regarded as wheat allergic due to recent anaphylactic reactions. The IgE-ab levels to all four wheat components were significantly higher in the group with wheat allergy compared to the group with no wheat allergy (p < 0.0001). Also, the severity of symptoms at challenge correlated with the IgE-ab levels to all four components (p < 0.05). IgE-ab levels to ω-5 gliadin correlated best with challenge outcome, and by additional analysis of gliadin, HMW- and LMW-glutenin IgE-abs all challenge positive children could be identified.

CONCLUSION

Many children diagnosed as wheat allergic have outgrown their allergy and are unnecessarily on a wheat-free diet. The levels of IgE-ab to wheat gluten-derived components correlated well with wheat challenge outcome and severity.

Early childhood IgE reactivity to pathogenesis-related class 10 proteins predicts allergic rhinitis in adolescence

BACKGROUND

Component-resolved diagnosis might improve the prediction of future allergy in young children.

OBJECTIVE

We sought to investigate the association between IgE reactivity to the pathogenesis-related class 10 (PR-10) protein family and allergic rhinitis to birch pollen (ARbp) from early childhood up to age 16 years.

METHOD

Questionnaire data and sera obtained at 4, 8, and 16 years of age from the Barn/Children Allergi/Allergy Milieu Stockholm Epidemiologic (BAMSE) study birth cohort were used. Sera from 764 children were analyzed for IgE reactivity to 9 PR-10 allergen proteins at the 3 time points by using an allergen chip based on ISAC technology. ARbp was defined as upper airway symptoms during birch pollen exposure.

RESULTS

IgE reactivity to Bet v 1 was found in 12%, 17%, and 25% of children at 4, 8, and 16 years of age. IgE reactivity of PR-10 proteins showed a hierarchic intrarelationship: Bet v 1 > Mal d 1 > Cor a 1.04 > Ara h 8 > Pru p 1 > Aln g 1 > Api g 1 > Act d 8 > Gly m 4. There was an increased risk of incidence and persistence of ARbp up to age 16 years with increasing levels of Bet v 1-specific IgE or increasing numbers of IgE-reactive PR-10 proteins at 4 years. Children with severe ARbp at age 16 years had higher levels of Bet v 1-specific IgE at age 4 years compared with children with mild symptoms.

CONCLUSION

ARbp at age 16 years can be predicted by analysis of IgE reactivity to PR-10 proteins in early childhood.

The high molecular weight glutenin subunit Bx7 allergen from wheat contains repetitive IgE epitopes

BACKGROUND

Wheat is one of the most common food allergen sources for children and adults. The aim of this study was to characterize new wheat allergens using an IgE discovery approach and to investigate their IgE epitopes.

METHODS

A cDNA expression library representing the wheat transcriptome was constructed in phage lambda gt11 and screened with IgE antibodies from wheat food allergic patients. IgE-reactive cDNA clones coding for portions of high molecular weight (HMW) glutenin subunits were identified by sequence analysis of positive clones. IgE epitopes were characterized using recombinant fragments from the HMW Bx7 and synthetic peptides thereof for testing of allergic patients' sera and in basophil degranulation assays.

RESULTS

We found that the major IgE-reactive areas of HMW glutenins are located in the repetitive regions of the protein and could show that two independent IgE-reactive fragments from HMW Bx7 contained repetitive IgE epitopes.

CONCLUSIONS

Our results demonstrate that IgE antibodies from wheat food allergic patients can recognize repetitive epitopes in one of the important wheat food allergens. Recombinant HMW Bx7 may be included into the panel of allergens for component-resolved diagnosis of wheat food allergy.

Advances in allergen-microarray technology for diagnosis and monitoring of allergy: the MeDALL allergen-chip

Allergy diagnosis based on purified allergen molecules provides detailed information regarding the individual sensitization profile of allergic patients, allows monitoring of the development of allergic disease and of the effect of therapies on the immune response to individual allergen molecules. Allergen microarrays contain a large variety of allergen molecules and thus allow the simultaneous detection of allergic patients' antibody reactivity profiles towards each of the allergen molecules with only minute amounts of serum. In this article we summarize recent progress in the field of allergen microarray technology and introduce the MeDALL allergen-chip which has been developed for the specific and sensitive monitoring of IgE and IgG reactivity profiles towards more than 170 allergen molecules in sera collected in European birth cohorts. MeDALL is a European research program in which allergen microarray technology is used for the monitoring of the development of allergic disease in childhood, to draw a geographic map of the recognition of clinically relevant allergens in different populations and to establish reactivity profiles which are associated with and predict certain disease manifestations. We describe technical advances of the MeDALL allergen-chip regarding specificity, sensitivity and its ability to deliver test results which are close to in vivo reactivity. In addition, the usefulness and numerous advantages of allergen microarrays for allergy research, refined allergy diagnosis, monitoring of disease, of the effects of therapies, for improving the prescription of specific immunotherapy and for prevention are discussed.

Molecular and immunological characterization of Tri a 36, a low molecular weight glutenin, as a novel major wheat food allergen

Wheat is an essential element in our nutrition but one of the most important food allergen sources. Wheat allergic patients often suffer from severe gastrointestinal and systemic allergic reactions after wheat ingestion. In this study, we report the molecular and immunological characterization of a new major wheat food allergen, Tri a 36. The cDNA coding for a C-terminal fragment of Tri a 36 was isolated by screening a wheat seed cDNA expression library with serum IgE from wheat food-allergic patients. Tri a 36 is a 369-aa protein with a hydrophobic 25-aa N-terminal leader peptide. According to sequence comparison it belongs to the low m.w. glutenin subunits, which can be found in a variety of cereals. The mature allergen contains an N-terminal domain, a repetitive domain that is rich in glutamine and proline residues, and three C-terminal domains with eight cysteine residues contributing to intra- and intermolecular disulfide bonds. Recombinant Tri a 36 was expressed in Escherichia coli and purified as soluble protein. It reacted with IgE Abs of ∼80% of wheat food-allergic patients, showed IgE cross-reactivity with related allergens in rye, barley, oat, spelt, and rice, and induced specific and dose-dependent basophil activation. Even after extensive in vitro gastric and duodenal digestion, Tri a 36 released distinct IgE-reactive fragments and was highly resistant against boiling. Thus, recombinant Tri a 36 is a major wheat food allergen that can be used for the molecular diagnosis of, and for the development of specific immunotherapy strategies against, wheat food allergy.