Hiroaki Matsuo

Exercise and aspirin increase levels of circulating gliadin peptides in patients with wheat-dependent exercise-induced anaphylaxis.

Background Food‐dependent exercise‐induced anaphylaxis (FDEIA) is an allergic reaction characteristically induced by intense exercise combined with the ingestion of causative food. Recent reports have shown that aspirin intake is a contributing factor in some patients with FDEIA. Wheat is known to be the most frequent causative food, and the IgE‐binding epitopes of a major wheat allergen (ω‐5 gliadin) in wheat‐dependent exercise induced anaphylaxis (WDEIA) have already been clarified. However, the mechanism of eliciting the symptom in WDEIA remains not fully understood.

Specific IgE Determination to Epitope Peptides of ω-5 Gliadin and High Molecular Weight Glutenin Subunit Is a Useful Tool for Diagnosis of Wheat-Dependent Exercise-Induced Anaphylaxis

Wheat ω-5 gliadin and a high m.w. glutenin subunit (HMW-glutenin) have been reported as major allergens in wheat-dependent exercise-induced anaphylaxis. A simultaneous detection of specific IgE to epitope sequences of both proteins is considered to be a reliable method for diagnosis of wheat-dependent exercise-induced anaphylaxis. However, the IgE-binding epitope of HMW-glutenin remains unknown. The aim of this study was to determine the IgE-binding epitopes of HMW-glutenin to establish a useful system of identifying patients with wheat-dependent exercise-induced anaphylaxis. For determination of IgE-binding epitopes of HMW-glutenin overlapping peptides were synthesized and reactivities of IgE Abs in the sera of patients to those peptides were analyzed. Three IgE-binding epitopes, QQPGQ, QQPGQGQQ, and QQSGQGQ, were identified within primary sequence of HMW-glutenin. Epitope peptides, which include IgE-binding sequences of ω-5 gliadin and a HMW-glutenin, were synthesized and peptide-specific IgE Abs were measured by CAP-System fluorescent enzyme immunoassay. Twenty-nine of 30 patients with wheat-dependent exercise-induced anaphylaxis had specific IgE Abs to these epitope peptides. None of the 25 sera from healthy subjects reacted to both epitope peptides. Twenty-five patients with atopic dermatitis who had specific IgE to wheat and/or gluten had very low or nonexistent levels of epitope peptide-specific IgE Abs. These results indicated that measurement of IgE levels specific to epitope peptides of ω-5 gliadin and HMW-glutenin is useful as an in vitro diagnostic method for the assessment of patients with wheat-dependent exercise-induced anaphylaxis.

Identification of the IgE-binding epitope in omega-5 gliadin, a major allergen in wheat-dependent exercise-induced anaphylaxis.

Wheat-dependent exercise-induced anaphylaxis (WDEIA) is a severe IgE-mediated allergic reaction provoked by the combination of wheat-ingestion with intensive physical exercise over the next few hours. Among wheat proteins, ω-5 gliadin, which is one of the components of fast ω-gliadin, has been reported as a major allergen in the anaphylaxis. In this study, we detected IgE-binding epitopes within the primary sequence of ω-5 gliadin using arrays of overlapping peptides synthesized on derivatized cellulose membranes. Sera from four patients with WDEIA having specific IgE to the fast ω-gliadin were used to probe the membrane. Seven epitopes, QQIPQQQ, QQLPQQQ, QQFPQQQ, QQSPEQQ, QQSPQQQ, QQYPQQQ, and PYPP, were detected within the primary sequence of ω-5 gliadin. By using sera of 15 patients, 4 of them, QQIPQQQ, QQFPQQQ, QQSPEQQ, and QQSPQQQ, were found to be dominant epitopes. Mutational analysis of the QQIPQQQ and QQFPQQQ indicated that amino acids at positions Gln1, Pro4, Gln5, Gln6, and Gln7 were critical for IgE binding. These results will provide a useful tool for developing safer wheat products in addition to diagnostic and immunotherapy techniques for WDEIA.

Sensitivity and specificity of recombinant omega-5 gliadin-specific IgE measurement for the diagnosis of wheat-dependent exercise-induced anaphylaxis.

Background:  A recent study has shown that the measurement of specific IgE antibodies to B‐cell epitope peptides of wheat ω‐5 gliadin (Pep A) and high molecular weight glutenin subunit (Pep B) are useful to diagnose wheat‐dependent exercise‐induced anaphylaxis (WDEIA).

Food-Dependent Exercise-Induced Anaphylaxis—Importance of Omega-5 Gliadin and HMW-Glutenin as Causative Antigens for Wheat-Dependent Exercise-Induced Anaphylaxis—

Food-dependent exercise-induced anaphylaxis (FDEIA) is a special form of food allergy where a food-intake alone does not induce any symptoms. However, allergic symptoms are elicited when triggering factors such as exercise or aspirin-intake are added after ingestion of the causative food. The most frequent causative foodstuff in Japan is wheat. The triggering factors, both exercise and aspirin-intake, facilitate allergen absorption from the gastrointestinal tract, resulting in allergic symptoms in the patients with wheat-dependent exercise-induced anaphylaxis (WDEIA). Analysis using purified wheat proteins revealed that approximately 80% of the patients with WDEIA have IgE reacting to omega-5 gliadin and the remaining of the patients to high molecular weight glutenin (HMW-glutenin). Simultaneous measurement of specific IgE to omega-5 gliadin and HMW-glutenin was found to be highly useful in diagnosing WDEIA compared with the routine diagnostic system for wheat.

Fast ω-gliadin is a major allergen in wheat-dependent exercise-induced anaphylaxis

Abstract Background: Wheat-dependent exercise-induced anaphylaxis is an anaphylaxy induced by physical exercise after ingestion of wheat. An immediate-type hypersensitivity to water/salt-insoluble fraction of wheat proteins (gluten) has been considered to underlie in this disease. Objective: The aim of the study is to determine the major allergen in Japanese patients with wheat-dependent exercise-induced anaphylaxis by using a panel of purified wheat gliadins and glutenins. Methods: Water/salt-insoluble wheat proteins, α-gliadin, β-gliadin, γ-gliadin, fast ω-gliadin, slow ω-gliadin, high molecular weight glutenin and low molecular weight glutenin, were purified, and five patients with wheat-dependent exercise-induced anaphylaxis, whose diagnose had been determined by positive-challenge test, were evaluated for skin prick test, dot-blotting test and CAP–RAST inhibition test by using these purified wheat proteins. Results: The fast ω-gliadin was the most potent allergen among these water/salt-insoluble proteins when evaluated by skin prick test and dot-blotting test. Fast and slow ω-gliadin, and γ-gliadin caused dose-dependent inhibition of the serum IgE-binding to solid-phase gluten in the patients. The incubation with fast ω-gliadin of the patients serum caused dose-dependent inhibition in the IgE-binding to γ-gliadin as well as slow ω-gliadin, indicating a cross-reactivity of these proteins in IgE-binding. Conclusion: We concluded that fast ω-gliadin is a major allergen among these water/salt-insoluble proteins for wheat-dependent exercise-induced anaphylaxis in Japanese patients, and IgE against fast ω-gliadin cross-reacts to γ-gliadin and slow ω-gliadin.

Molecular cloning, recombinant expression and IgE‐binding epitope of ω‐5 gliadin, a major allergen in wheat‐dependent exercise‐induced anaphylaxis

Wheatω‐5 gliadin has been identified as a major allergen in wheat‐dependent exercise‐induced anaphylaxis. We have detected seven IgE‐binding epitopes in primary sequence of the protein. We newly identified four additional IgE‐binding epitope sequences, QQFHQQQ, QSPEQQQ, YQQYPQQ and QQPPQQ, in three patients with wheat‐dependent exercise‐induced anaphylaxis in this study. Diagnosis and therapy of food allergy would benefit from the availability of defined recombinant allergens. However, because ω‐5 gliadin gene has not been cloned, recombinant protein is currently unavailable. We sought to clone the ω‐5 gliadin gene and produce the homogeneous recombinant protein for use in an in vitro diagnostic tool. Using a PCR‐based strategy we isolated two full‐length ω‐5 gliadin genes, designated ω‐5 and ω‐5b, from wheat genomic DNA and determined the nucleotide sequences. The protein encoded by ω‐5a was predicted to be 439 amino acids long with a calculated mass of 53 kDa; the ω‐5b gene would encode a 393 amino acid, but it contains two stop codons indicating that ω‐5b is pseudogene. The C‐terminal half (178 amino acids) of the ω‐5a gliadin protein, including all 11 IgE‐binding epitope sequences, was expressed in Escherichia coli by means of the pET system and purified using RP‐HPLC. Western blot analysis and dot blot inhibition assay of recombinant and native ω‐5 gliadin purified from wheat flour demonstrated that recombinant protein had IgE‐binding ability. Our results suggest that the recombinant protein can be a useful tool for identifying patients with wheat‐dependent exercise‐induced anaphylaxis in vitro.

IgE antibodies to ω‐5 gliadin associate with immediate symptoms on oral wheat challenge in Japanese children

Background:  Gliadins have been implicated in immunoglobulin E (IgE)‐mediated allergy to ingested wheat and ω‐5‐gliadin is known to represent a major allergen in wheat‐dependent exercise‐induced anaphylaxis. Less known is whether ω‐5‐gliadin is a clinically relevant allergen in children with immediate allergy to ingested wheat. This study investigates whether specific IgE antibodies to ω‐5‐gliadin (sIgE‐ω‐5‐gliadin‐ab) could be used as a marker for oral wheat challenge outcome in wheat‐sensitized children. A secondary objective was to study whether the level of sIgE‐ω‐5‐gliadin was related to symptom severity in children with a positive challenge test.

Increased production of vascular endothelial growth factor in the lesions of atopic dermatitis

Atopic dermatitis (AD) is a chronic inflammatory skin disease characterized by severe itching, erythema and edema resistant to anti-histamine therapy. Vascular endothelial growth factor (VEGF) is a potent agent that causes hyperpermeability of blood vessels and endothelial cell proliferation, and might be involved in the persisting erythema and edema in AD. In this study, we used extraction of stratum corneum with physiological saline to detect VEGF produced in the lesions of AD. Biological activity of VEGF was assayed by proliferation of cultured human umbilical vein endothelial cells in vitro. As a result, we found that the amount of VEGF produced in lesional scales was approximately 25 times higher than that in normal stratum corneum. Moreover, VEGF 121 isoform that exclusively induces hyperpermeability of blood vessels was a predominant component in the lesional scales suggesting that this factor plays an important role in the persisting erythema and edema in the AD lesions.

Common food allergens and their IgE-binding epitopes

Food allergy is an adverse immune response to certain kinds of food. Although any food can cause allergic reactions, chicken egg, cows milk, wheat, shellfish, fruit, and buckwheat account for 75% of food allergies in Japan. Allergen-specific immunoglobulin E (IgE) antibodies play a pivotal role in the development of food allergy. Recent advances in molecular biological techniques have enabled the efficient analysis of food allergens. As a result, many food allergens have been identified, and their molecular structure and IgE-binding epitopes have also been identified. Studies of allergens have demonstrated that IgE antibodies specific to allergen components and/or the peptide epitopes are good indicators for the identification of patients with food allergy, prediction of clinical severity and development of tolerance. In this review, we summarize our current knowledge regarding the allergens and IgE epitopes in the well-researched allergies to chicken egg, cows milk, wheat, shrimp, and peanut.