Specific IgE determination to epitope peptides of omega-5 gliadin and high molecular weight glutenin subunit is a useful tool for diagnosis of wheat-dependent exercise-induced anaphylaxis

Allergenic Biomarkers in the Molecular Diagnosis of IgE-Mediated Wheat Allergy

IgE-mediated wheat allergy can take on various forms, including childhood food allergy to wheat, wheat-dependent exercise-induced anaphylaxis in young adults, baker's respiratory allergy/asthma in workers exposed to wheat flour inhalation, and contact urticaria that is caused by hydrolyzed wheat proteins in some cosmetics, and that is sometimes associated with a food allergy. Singleplex and multiplex immunoassays detect specific IgE antibodies to wheat allergenic molecular biomarkers such as omega-5 gliadin Tri a 19, lipid transfer protein Tri a 14, and alpha-amylase inhibitors. The fluorescence enzyme immunoassay with capsulated cellulose polymer solid-phase coupled allergens is a commonly used singleplex assay. Multiplex methods include the ELISA-based macroarray immunoassay using nano-bead technology and a microarray immunoassay on polymer-coated slides. Another promising diagnostic tool is the basophil activation test performed with omega-5 gliadin and other wheat protein types. Detailed comprehension of the structural and immunological features of the numerous wheat allergens significant in clinical settings is imperative for advancing diagnostic biomarkers for IgE-mediated wheat allergies.

Effect of Adding Chestnut Inner Skin on Allergenic Protein, Antioxidant Properties, and Quality of Bread

Wheat-dependent, exercise-induced anaphylaxis has no fundamental cure and requires patients to refrain from wheat consumption or to rest after eating. Although hypoallergenic wheat production by enzymatic degradation or thioredoxin treatment has been investigated, challenges still exist in terms of labor and efficacy. We investigated a hypoallergenic wheat product manufacturing technology that takes advantage of the property of tannins to bind tightly to proteins. Commercially available bread wheat (BW) and hypoallergenic wheat (1BS-18 "Minaminokaori", 1BS-18M) were used. Chestnut inner skin (CIS) was selected as a tannin material based on the screening of breads with added unused parts of persimmon and chestnut. Hypoallergenicity was evaluated using Western blotting. The effect of CIS addition on the antioxidative properties of bread was also measured. For both BW and 1BS-18M, CIS addition reduced the immunoreactivity of wheat allergens. Antioxidant activities increased with increasing CIS substitution. However, 10% CIS-substituted breads were substantially less puffy. Five percent CIS substitution was optimal for achieving low allergenicity, while maintaining bread quality. The strategy investigated herein can reduce allergies related to wheat bread consumption. In this study, the evaluation of hypoallergenicity was limited to instrumental analysis. In the future, we will evaluate hypoallergenicity through clinical trials in humans.

Identification of RNAi hypoallergic bread wheat lines for wheat-dependent exercise-induced anaphylaxis patients

Wheat-dependent exercise-induced anaphylaxis (WDEIA) is one of the most severe forms of wheat allergy. It occurs in patients when they exercise after ingesting wheat-containing foods. Nowadays, the only possible alternative for WDEIA patients is to avoid such foods. This study investigated the potential of six RNA of interference (RNAi) wheat lines with low-prolamin content as alternatives for WDEIA patients. For that purpose, a high performance-liquid chromatography (HPLC) analysis was performed to evaluate differences in gluten protein fractions among these lines. Next, western blots were conducted to measure the immunoglobulin E (IgE) reactivity to wheat proteins in sera from five WDEIA patients. Additionally, monoclonal antibodies (moAb) recognition sites and the IgE binding sites were searched in all peptides identified by LC-MS/MS after protein digestion. The results showed a 61.4%-81.2% reduction in the gliadin content of the RNAi lines, accompanied by an increase in their high-molecular weight (HMW) glutenin content compared to the wild type bread wheat line (WT). In all cases, the reduction in gliadin content correlated with a decrease in IgE reactivity observed in the sera of WDEIA patients, highlighting the E82 and H320 lines. These two RNAi lines exhibited a ≤90% reduction in IgE reactivity. This reduction could be attributed to an absence of IgE binding sites associated with α- and ω5-gliadins, which were present in the WT. Overall, these lines offer a potential alternative for foodstuff for individuals with WDEIA.

Comprehensive amino acid composition analysis of seed storage proteins of cereals and legumes: identification and understanding of intrinsically disordered and allergenic peptides

The seed storage proteins of cereal and legumes are the primary source of amino acids which are required for sustaining the nitrogen and carbon demands during germination and growth. Humans derive most of their dietary proteins from storage proteins in form of a wide variety of foods, for consumption. The amino acid content of most of these proteins is biased and the need for this biasness is not understood. The high abundance of proline, glutamine, and cysteine in cereals makes the gluten fraction viscoelastic. The cereal proteins have less charge and legume proteins have more charge on them. Their non-polar amino acid distribution has large variations. These characteristics are strongly responsible for the partial and complete unfolding of several domains of the storage proteins. Many of the storage proteins share a highly conserved structural feature within the cupin superfamily spread across all kingdoms of life. The intrinsically disordered viscoelastic proteins help in making dough which is vital for the quality of bread. Unfolded regions harbor more immunogenic sequences and cause food-related allergies and intolerance. We have discussed these properties in terms of comparison of cereal and legume storage protein sequences and allergy. Our study supports the findings that large disordered regions contain allergen-representative peptides. Interestingly, a high number of allergen-representative peptides were cleavable by digestive enzymes. Furthermore, unfolded storage proteins mimic microbial immunogens to induce a memory immune response. Results findings can be used to guide the understanding of immunological characteristics of storage proteins and may assist in treatment decisions for food allergy.Communicated by Ramaswamy H. Sarma.

Dynamic structural analysis-based epitope prediction of Exendin-4 in aqueous solution

The study of epitopes has a broad range of applications in drug discovery, vaccine design, and immunotherapy. In this study, an epitope prediction method was developed based on the dynamic structure of protein antigens. Solvent accessible surface area, charge, and root mean square fluctuation were introduced as the key residue property parameters. The epitope prediction algorithm was established by constructing a three-parameter complex metrics of seven-peptide groups. The method was applied to predict the epitopes of Exendin-4, an effective antidiabetic drug. The epitopes of both the natural and C-terminal amidated forms of Exendin-4 were predicted and compared in their folded and intermediate states. In the folded state, the epitopes of natural Exendin-4 (His1-Phe6 and Asp9-Val19) were found to be nearly identical to the epitopes of C-terminal aminated Exendin-4 (His1-Thr7 and Asp9-Val19). In the intermediate state, however, the epitopes of natural Exendin-4 (His1-Gly4, Phe6 and Lys12-Arg20) covered fewer amino acids than the epitopes of C-terminal aminated Exendin-4 (His1-Gly4, Phe6, Asp9-Val19 and Trp25-Lys27). The comparison with the results from other prediction tools demonstrates the reliability of our predicted epitopes of Exendin-4.

Low Allergenicity in Processed Wheat Flour Products Using Tannins from Agri-Food Wastes

The present study aimed to investigate the effect of the addition of tannins from unutilized resources on wheat allergen reduction, antioxidant properties, and quality by substituting 3%, 5%, and 10% of the flour with chestnut inner skin (CIS) and young persimmon fruit (YPF) powders to produce cookies. The enzyme-linked immunosorbent assay and Western blotting showed significantly lower wheat allergen content in CIS- or YPF-substituted cookies than in control cookies, and this effect was pronounced for CIS-substituted cookies. In addition, the tannin content and antioxidant properties of the CIS- or YPF-substituted cookies were markedly higher than those of the control cookies. Quality analysis of the CIS- and YPF-substituted cookies showed that the specific volume and spread factor, which are quality indicators for cookies, were slightly lower in the CIS- and YPF-substituted cookies than in the control cookies. Compared to the control, CIS substitution did not affect the breaking stress and total energy values of the cookies; however, YPF substitution at 10% increased these values. Color was also affected by the addition of CIS and YPF. The results suggest that the addition of CIS and YPF can reduce wheat allergens in cookies and improve tannin content and antioxidant properties.

Cross-reactive epitopes and their role in food allergy

Allergenic cross-reactivity among food allergens complicates the diagnosis and management of food allergy. This can result in many patients being sensitized (having allergen-specific IgE) to foods without exhibiting clinical reactivity. Some food groups such as shellfish, fish, tree nuts, and peanuts have very high rates of cross-reactivity. In contrast, relatively low rates are noted for grains and milk, whereas many other food families have variable rates of cross-reactivity or are not well studied. Although classical cross-reactive carbohydrate determinants are clinically not relevant, α-Gal in red meat through tick bites can lead to severe reactions. Multiple sensitizations to tree nuts complicate the diagnosis and management of patients allergic to peanut and tree nut. This review discusses cross-reactive allergens and cross-reactive carbohydrate determinants in the major food groups, and where available, describes their B-cell and T-cell epitopes. The clinical relevance of these cross-reactive B-cell and T-cell epitopes is highlighted and their possible impact on allergen-specific immunotherapy for food allergy is discussed.

A Narrative Mini Review on Current Status of Hypoallergenic Wheat Development for IgE-Mediated Wheat Allergy, Wheat-Dependent Exercise-Induced Anaphylaxis

Immunoglobulin E (IgE)-mediated food allergies to wheat that develop after school age typically shows a type of wheat-dependent exercise-induced anaphylaxis (WDEIA). At present, avoidance of wheat products or postprandial rest after ingesting wheat is recommended for patients with WDEIA, depending on the severity of the allergy symptoms. ω5-Gliadin has been identified as the major allergen in WDEIA. In addition, α/β-, γ-, and ω1,2-gliadins, high and low molecular weight-glutenins, and a few water-soluble wheat proteins have been identified as IgE-binding allergens in a small proportion of patients with IgE-mediated wheat allergies. A variety of approaches have been manufactured to develop hypoallergenic wheat products that can be consumed by patients with IgE-mediated wheat allergies. In order to analyze such approaches, and to contribute to the further improvement, this study outlined the current status of these hypoallergenic wheat productions, including wheat lines with a reduced allergenicity that are mostly constructed for the patients sensitized to ω5-gliadin, hypoallergenic wheat by enzymic degradation/ion exchanger deamidation, and hypoallergenic wheat by thioredoxin treatment. The wheat products obtained by these approaches significantly reduced the reactivity of Serum IgE in wheat-allergic patients. However, either these were not effective on some populations of the patients, or low-level IgE-reactivity to some allergens of the products was observed in the patients. These results highlight some of the difficulties faced in creating hypoallergenic wheat products or hypoallergenic wheat lines through either traditional breeding or biotechnology approaches in developing hypoallergenic wheat completely safe for all the patients allergic to wheat.

Basophil Activation to Gluten and Non-Gluten Proteins in Wheat-Dependent Exercise-Induced Anaphylaxis

Wheat-dependent exercise-induced anaphylaxis (WDEIA) is a cofactor-induced wheat allergy. Gluten proteins, especially ω5-gliadins, are known as major allergens, but partially hydrolyzed wheat proteins (HWPs) also play a role. Our study investigated the link between the molecular composition of gluten or HWP and allergenicity. Saline extracts of gluten (G), gluten with reduced content of ω5-gliadins (G-ω5), slightly treated HWPs (sHWPs), and extensively treated HWPs (eHWPs) were prepared as allergen test solutions and their allergenicity assessed using the skin prick test and basophil activation test (BAT) on twelve patients with WDEIA and ten controls. Complementary sodium dodecyl-sulfate polyacrylamide gel electrophoresis (SDS-PAGE), high-performance liquid chromatography (HPLC), and mass spectrometry (MS) analyses revealed that non-gluten proteins, mainly α-amylase/trypsin inhibitors (ATIs), were predominant in the allergen test solutions of G, G-ω5, and sHWPs. Only eHWPs contained gliadins and glutenins as major fraction. All allergen test solutions induced significantly higher %CD63⁺ basophils/anti-FcεRI ratios in patients compared with controls. BAT using sHWPs yielded 100% sensitivity and 83% specificity at optimal cut-off and may be useful as another tool in WDEIA diagnosis. Our findings indicate that non-gluten proteins carrying yet unidentified allergenic epitopes appear to be relevant in WDEIA. Further research is needed to clarify the role of nutritional ATIs in WDEIA and identify specific mechanisms of immune activation.

The basophil activation test differentiates between patients with wheat-dependent exercise-induced anaphylaxis and control subjects using gluten and isolated gluten protein types

BACKGROUND

Oral food challenge using gluten and cofactors is the gold standard to diagnose wheat-dependent exercise-induced anaphylaxis (WDEIA), but this procedure puts patients at risk of an anaphylactic reaction. Specific IgE to ω5-gliadins as major allergens and skin prick tests to wheat may yield negative results. Thus, we designed a proof-of-principle study to investigate the utility of the basophil activation test (BAT) for WDEIA diagnosis.

METHODS

Different gluten protein types (GPT; α-, γ-, ω1,2- and ω5-gliadins, high-molecular-weight glutenin subunits [HMW-GS] and low-molecular-weight glutenin subunits [LMW-GS]) and gluten were used in different concentrations to measure basophil activation in 12 challenge-confirmed WDEIA patients and 10 control subjects. The results were compared to routine allergy diagnostics. Parameters analyzed include the percentage of CD63+ basophils, the ratio of %CD63+ basophils induced by GPT/gluten to %CD63+ basophils induced by anti-FcεRI antibody, area under the dose-response curve and test sensitivity and specificity.

RESULTS

GPT and gluten induced strong basophil activation for %CD63+ basophils and for %CD63+/anti-FcɛRI ratio in a dose-dependent manner in patients, but not in controls (p < 0.001, respectively). BAT performance differed from acceptable (0.73 for LMW-GS) to excellent (0.91 for ω5-gliadins) depending on the specific GPT as evaluated by the area under the receiver operating characteristic curve. Patients showed individual sensitization profiles. After determination of the best cut-off points, ω5-gliadins and HMW-GS showed the best discrimination between patients and controls with a sensitivity/specificity of 100/70 and 75/100, respectively.

CONCLUSION

This study shows the alternative role of BAT in better defining WDEIA and the causative wheat allergens. The best BAT parameters to distinguish WDEIA patients from controls were %CD63+ basophil values for ω5-gliadins and HMW-GS.

Identification of allergens for food-dependent exercise-induced anaphylaxis to shrimp

Shrimp is a causative food that elicits food-dependent exercise-induced anaphylaxis (FDEIA). In this study, we sought to identify IgE-binding allergens in patients with shrimp-FDEIA. Sera were obtained from eight patients with shrimp-FDEIA and two healthy control subjects. Proteins were extracted from four shrimp species by homogenization in Tris buffer. Immunoblot analysis revealed that IgE from patient sera bound strongly to a 70-kDa and a 43-kDa protein in a preparation of Tris-soluble extracts from Litopenaeus vannamei. Mass spectrometry identified the 70-kDa and 43-kDa proteins as a P75 homologue and fructose 1,6-bisphosphate aldolase (FBPA), respectively. To confirm that the putative shrimp allergens were specifically recognized by serum IgE from shrimp-FDEIA patients, the two proteins were purified by ammonium sulfate precipitation followed by reversed-phase HPLC and/or anion-exchange hydrophobic interaction chromatography and then subjected to immunoblot analysis. Purified P75 homologue and FBPA were positively bound by serum IgE from one and three, respectively, of the eight patients with shrimp-FDEIA, but not by sera from control subjects. Thus, P75 homologue and FBPA are identified as IgE-binding allergens for shrimp-FDEIA. These findings could be useful for the development of diagnostic tools and desensitization therapy for shrimp-FDEIA patients.

Exercise-induced allergic reactions on desensitization to wheat after rush oral immunotherapy

BACKGROUND

The effect of oral immunotherapy (OIT) on wheat allergy is promising in terms of the potential to obtain desensitization; however, the frequency of exercise-induced allergic reactions on desensitization (EIARDs) and the associated risk factors remain to be determined.

METHODS

Twenty-five patients underwent rush OIT for wheat allergy, and 21 achieved the full-dose intake of wheat products (5 g of wheat protein). Exercise-provocation tests were repeatedly performed after the ingestion of a full-dose wheat product. The time-course of the levels of the specific IgEs (sIgE) to wheat extract, total gliadin, deamidated gliadin, recombinant gliadin components (α/β-, γ- and ω-5-), and glutenin (high and low molecular weight) components was analyzed using ImmunoCAP^® , ELISA, or IgE immunoblotting.

RESULTS

Fourteen patients (66.7%) were diagnosed as EIARD+, which remained 5 years after rush OIT in 11 patients (52.4%). There were no differences in the clinical backgrounds of the EIARD+ and EIARD- patients. However, EIARD+ patients showed significantly higher sIgE levels to all gliadin and glutenin components than EIARD- patients before OIT. The sIgE levels to each component decreased equally after 1 and 2 years of OIT. On IgE immunoblotting, sera from all patients reacted to the multiple gluten bands, and some reacted to the water-soluble bands. The intensity of all IgE-reactive bands also became equally lighter after OIT.

CONCLUSIONS

EIARDs were frequently observed and remained for a long period after successful OIT for wheat allergy. None of the specific wheat components were found to contribute to EIARDs.

Genomic and functional genomics analyses of gluten proteins and prospect for simultaneous improvement of end-use and health-related traits in wheat

KEY MESSAGE

Recent genomic and functional genomics analyses have substantially improved the understanding on gluten proteins, which are important determinants of wheat grain quality traits. The new insights obtained and the availability of precise, versatile and high-throughput genome editing technologies will accelerate simultaneous improvement of wheat end-use and health-related traits. Being a major staple food crop in the world, wheat provides an indispensable source of dietary energy and nutrients to the human population. As worldwide population grows and living standards rise in both developed and developing countries, the demand for wheat with high quality attributes increases globally. However, efficient breeding of high-quality wheat depends on critically the knowledge on gluten proteins, which mainly include several families of prolamin proteins specifically accumulated in the endospermic tissues of grains. Although gluten proteins have been studied for many decades, efficient manipulation of these proteins for simultaneous enhancement of end-use and health-related traits has been difficult because of high complexities in their expression, function and genetic variation. However, recent genomic and functional genomics analyses have substantially improved the understanding on gluten proteins. Therefore, the main objective of this review is to summarize the genomic and functional genomics information obtained in the last 10 years on gluten protein chromosome loci and genes and the cis- and trans-factors regulating their expression in the grains, as well as the efforts in elucidating the involvement of gluten proteins in several wheat sensitivities affecting genetically susceptible human individuals. The new insights gathered, plus the availability of precise, versatile and high-throughput genome editing technologies, promise to speed up the concurrent improvement of wheat end-use and health-related traits and the development of high-quality cultivars for different consumption needs.

Scientific Opinion related to a notification from Lyckeby Starch AB on barley starch to be used in the manufacturing of several foods as ingredient, of the food additive modified starch and of glucose syrups pursuant to Article 21(2) of Regulation (EU) No 1169/2011 - for permanent exemption from labelling

Following a request from the European Commission, the EFSA Panel on Nutrition, Novel Foods and Food Allergens (NDA) was asked to deliver a scientific opinion on barley starch to be used in the manufacturing of several foods as ingredient, of the food additive modified starch and of glucose syrups pursuant to Article 21(2) of Regulation (EU) No 1169/2011, as notified by Lyckeby Starch AB. The applicant provided information on the manufacturing process and data on the content of total protein, gluten and allergenic proteins in barley starch. The applicant also performed IgE-binding in vitro tests, which were considered inconclusive by the Panel. No human intervention studies with barley starch or food products thereof were provided by the applicant, except for a DBPCFC with barley starch hydrolysate in cereal allergic individuals. The Panel notes that glucose syrups based on barley have been already exempted from allergen labelling as per Annex II of Regulation (EU) No 1169/2011 and that the current application is for the exemption from labelling of all foods manufactured from barley starch. In all the scenarios considered for the anticipated intake, the calculated total protein intake from barley starch was above the MED/MOED for wheat (expressed in mg of wheat protein) in adults (10 mg) and children (2 mg). The Panel concludes that the data available are insufficient to conclude on the likelihood of adverse allergic reactions in cereal-allergic individuals upon consumption of barley starch under the conditions of use proposed by the applicant, and that the consumption of foodstuffs produced from barley starch as starting (raw) material or foodstuffs containing barley starch as an ingredient is unlikely to cause an adverse reaction in individuals with coeliac disease who are not allergic to cereals, provided that the value of gluten for 'gluten-free' foods (20 mg/kg) is not exceeded.

IgE and IgG4 responses to shrimp allergen tropomyosin and its epitopes in patients from coastal areas of northern China

Sensitization to allergens and their peptides varies among patients due to geographical or ethnic differences. The present study aimed to investigate immunoglobulin (Ig)E and IgG₄ responses to tropomyosin and its peptides in shrimp allergic patients from northern China. A total of 92 subjects were studied, including 35 shrimp allergic patients, 29 patients with house dust mite (HDM) and/or cockroach allergic patients and 28 healthy volunteers. Serum IgE and IgG₄ antibodies to recombinant shrimp tropomyosin (rPen a 1) and its peptides were measured by means of a light-initiated chemiluminescent assay. A total of 9 major sequential epitopes of Pen a 1 reported in the literature were synthesized. Of 35 shrimp allergic patients, 25 (71.4%) had positive Pen 1-specific IgE (sIgE) antibodies and 22 (62.9%) contained measurable rPen a 1-specific IgG₄ (sIgG₄) antibodies. A strong IgG₄ response accompanied the presence of IgE to Pen a 1. None of the patients with HDM and/or cockroach allergy demonstrated IgE reactivity to rPen a 1. The reaction frequency of IgE binding epitope was 20–48%, while that of IgG₄ binding epitope was 63.6–3.9%. The IgE and IgG₄ recognition patterns of the tropomyosin peptides demonstrated high interpatient heterogeneity. Diversity of IgE binding epitopes was positively correlated with Pen a 1 sIgE levels. In the study population, tropomyosin was a major allergen recognized by the majority of shrimp allergic patients, which is consistent with previous reports. However, none of the 9 epitopes are major (reaction frequency >50%) IgE-binding regions, indicating the epitopes profile may be different in other regions.

A Comprehensive Peptidomic Approach to Characterize the Protein Profile of Selected Durum Wheat Genotypes: Implication for Coeliac Disease and Wheat Allergy

The wheat varietal selection undertaken by breeders in recent decades has been tailored mainly to improve technological and productivity-related traits; however, the latter has resulted in a considerable impoverishment of the genetic diversity of wheat-based products available on the market. This pitfall has encouraged researchers to revalue the natural diversity of cultivated and non-cultivated wheat genotypes in light of their different toxic/immunogenic potential for celiac disease and wheat-allergic patients. In the present investigation, an advanced proteomic approach was designed for the global characterization of the protein profile of selected tetraploid wheat genotypes (Triticum turgidum). The approach combined proteins/peptides sequence information retrieved by specific enzymatic digestions (single and dual proteolytic enzymes) with protein digestibility information disclosed by means of in-vitro simulated human gastroduodenal digestion experiments. In both cases, the peptide pools were characterized by discovery analysis with liquid chromatography high-resolution tandem mass spectrometry, and specific amino acid sequences were identified via commercial software. The peptide list was screened for in silico toxicity/immunogenicity risk assessment, with the aid of various open-source bioinformatics tools for epitopes matching. Given the global information provided by the designed proteomic approach, the in silico risk assessment not only tackled toxicity implication for celiac disease patients, but also scouted for immunogenic sequences relevant for wheat allergic patients, achieving a comprehensive characterization of the protein profile of the selected genotypes. These latter were assessed to encrypt a variable number of toxic/immunogenic epitopes for celiac disease and wheat allergy, and as such they could represent convenient bases for breeding practices and for the development of new detoxification strategies.

Wheat-dependent exercise-induced anaphylaxis in Chinese people: a clinical research on 33 cases with antigenic analysis of wheat proteins

BACKGROUND

Wheat-dependent exercise-induced anaphylaxis (WDEIA) is a severe allergic condition in which wheat ingestion together followed by physical exercise induces anaphylaxis. For patients with WDEIA, omega-5 gliadin is considered to be one of the major allergens.

AIM

To analyse the clinical features and allergen spectrum of WDEIA and to investigate the relationship between WDEIA and serum levels of platelet-activating factor (PAF), interleukin (IL)-9 and IL-33.

METHODS

Medical histories and conditions of WDEIA cases were collected and summarized, with allergen tests of wheat proteins measured at the same visit. Of the 33 patients enrolled, 13 also had serum levels of PAF, IL-9 and IL-33 measured. The healthy control (HC) group consisted of 13 healthy individuals, who also underwent both the wheat-protein allergen tests and the inflammatory-mediator tests.

RESULTS

All patients experienced severe allergic reaction during exercise after wheat ingestion. Manifestations of WDEIA included facial oedema, generalized urticaria and respiratory symptoms. Unconsciousness was also observed in 21 cases. In the patient group, 57.6% were confirmed as hypersensitive to glyceraldehyde-3-phosphate dehydrogenase (GAPDH), while 54.5% were allergic to omega-5 gliadin. PAF concentration was significantly higher in patients with WDEIA compared with HCs, whereas there was no significant difference in IL-9 or IL-33 between the two groups.

CONCLUSIONS

WDEIA is a rare type of anaphylaxis. GAPDH and omega-5 gliadin may be the most common allergy-causing wheat proteins for Chinese people. PAF may be associated with the onset and development of WDEIA.

A New Diagnostic Criteria of Wheat-Dependent, Exercise-Induced Anaphylaxis in China

Background:

Wheat-dependent, exercise-induced anaphylaxis (WDEIA) is an allergic reaction induced by intense exercise combined with wheat ingestion. The gold standard for diagnosis of WDEIA is a food exercise challenge; however, this test is unacceptable for Chinese WDEIA patients and unable to be approved by the Ethics Committee of Chinese hospitals due to substantial risk. There are no diagnostic criteria for Chinese WDEIA patients. The aim of present study was to propose new practical diagnosis criteria for Chinese WDEIA patients.

Methods:

We prospectively included 283 clinically diagnosed WDEIA patients from January 1, 2010 to June 30, 2014, and in the meanwhile, three groups were enrolled which included 133 patients with the history of anaphylaxis induced by food other than wheat, 186 recurrent urticaria patients, and 94 healthy participants. Clinical comprehensive evaluation by allergists used as the reference gold standard, receiver operator characteristic (ROC) curves were plotted, areas under curve (AUC) for specific immunoglobin E (sIgE) were compared to evaluate the diagnostic value of IgE specific to wheat, gluten, and ω-5 gliadin. Patients were followed up by telephone questionnaire 1 year after diagnosis.

Results:

We reviewed 567 anaphylactic reactions in 283 WDEIA patients. Of these anaphylactic reactions, 415 (73.3%) reactions were potentially life-threatening anaphylaxis. Among the 567 anaphylactic reactions, 75% (425/567) occurred during exercise. The highest AUC (0.910) was observed for sIgE for gluten, followed by omega-5 gliadin (AUC 0.879). Combined gluten- and ω-5 gliadin-specific IgE testing provided sensitivity and specificity of 73.1% and 99.0%, respectively. During the 1-year follow-up period, repeat anaphylaxis was rare when patients observed strict avoidance of wheat products combined with exercise or other triggering agents.

Conclusions:

In this study, we proposed diagnostic criteria and management of WDEIA patients in China. Our present study suggested that confirmed anaphylactic reactions triggered by wheat with positive sIgE to gluten and omega-5-gliadin may provide supportive evidence for clinicians to make WDEIA diagnosis without performing a food exercise challenge.

Allergic reactions to hydrolysed wheat proteins: clinical aspects and molecular structures of the allergens involved

Wheat gluten can be chemically or enzymatically hydrolysed to produce functional ingredients useful in food and cosmetics. However severe allergies to hydrolysed wheat proteins (HWP) have been described in Europe and Japan since the early 2000's. Triggering proteins and IgE epitopes were described both for French and Japanese cohorts and appeared remarkably similar leading to define a new wheat allergic entity. Deamidation induced by functionalisation generate neo-allergens responsible for this particular allergy. This article aims to review the processes leading to deamidation and the clinical features of the patients suffering from this allergy. Then the molecular determinants involved in HWP-allergy were exhaustively described and hypothesis regarding the sensitizing mechanism of HWP-allergy are discussed. Finally, current regulation and tools aiming at managing this risk associated with HWP are presented.

Differences in gluten protein composition between old and modern durum wheat genotypes in relation to 20th century breeding in Italy

The impact of breeding on grain yields of wheat varieties released during the 20th century has been extensively studied, whereas less information is available on the changes in gluten quality associated with effects on the amount and composition of glutenins and gliadins. In order to explore the effects of breeding during the 20th century on gluten quality of durum wheat for processing and health we have compared a set of old and modern Italian genotypes grown under Mediterranean conditions. The better technological performance observed for the modern varieties was found to be due not only to the introgression of superior alleles of high (HMW-GS) and low molecular weight (LMW-GS) glutenin subunits encoded at Glu-B1 and Glu-B3 loci, but also to differential expression of specific storage proteins. In particular, the higher gluten index observed in modern genotypes was correlated with an increased glutenin/gliadin ratio and the expression of B-type LMW-GS which was, on average, two times higher in the modern than in the old group of durum wheat genotypes. By contrast, no significant differences were found between old and modern durum wheat genotypes in relation to the expression of α-type and γ-type gliadins which are major fractions that trigger coeliac disease (CD) in susceptible individuals. Furthermore, a drastic decrease was observed in the expression of ω-type gliadins in the modern genotypes, mainly ω-5 gliadin (also known as Tri a 19) which is a major allergen in wheat dependent exercise induced anaphylaxis (WDEIA). Immunological and 2DE SDS-PAGE analyses indicated that these differences could be related either to a general down-regulation or to differences in numbers of isoforms. Lower rainfall during grain filling period was related to overall higher expression of HMW-GS and ω-gliadins. In conclusion, breeding activity carried out in Italy during the 20th century appears to have improved durum wheat gluten quality, both in relation to technological performance and allergenic potential.

A curated gluten protein sequence database to support development of proteomics methods for determination of gluten in gluten-free foods

The unique physiochemical properties of wheat gluten enable a diverse range of food products to be manufactured. However, gluten triggers coeliac disease, a condition which is treated using a gluten-free diet. Analytical methods are required to confirm if foods are gluten-free, but current immunoassay-based methods can unreliable and proteomic methods offer an alternative but require comprehensive and well annotated sequence databases which are lacking for gluten. A manually a curated database (GluPro V1.0) of gluten proteins, comprising 630 discrete unique full length protein sequences has been compiled. It is representative of the different types of gliadin and glutenin components found in gluten. An in silico comparison of their coeliac toxicity was undertaken by analysing the distribution of coeliac toxic motifs. This demonstrated that whilst the α-gliadin proteins contained more toxic motifs, these were distributed across all gluten protein sub-types. Comparison of annotations observed using a discovery proteomics dataset acquired using ion mobility MS/MS showed that more reliable identifications were obtained using the GluPro V1.0 database compared to the complete reviewed Viridiplantae database. This highlights the value of a curated sequence database specifically designed to support the proteomic workflows and the development of methods to detect and quantify gluten.

SIGNIFICANCE

We have constructed the first manually curated open-source wheat gluten protein sequence database (GluPro V1.0) in a FASTA format to support the application of proteomic methods for gluten protein detection and quantification. We have also analysed the manually verified sequences to give the first comprehensive overview of the distribution of sequences able to elicit a reaction in coeliac disease, the prevalent form of gluten intolerance. Provision of this database will improve the reliability of gluten protein identification by proteomic analysis, and aid the development of targeted mass spectrometry methods in line with Codex Alimentarius Commission requirements for foods designed to meet the needs of gluten intolerant individuals.

Evaluation of gluten in gluten-free-labeled foods and assessment of exposure level to gluten among celiac patients in Lebanon

The aim of the study was to evaluate gluten contamination in all the gluten-free (GF)-labeled food products sold in Lebanon. Over a 2-year period, a total of 173 food samples collected from 135 brand names were analyzed. Gluten contamination was detected in 33 of 173 (19%) samples, and its content ranged between 2.5 and >80 mg kg^-1. In 10 of the 173 samples (6%), the quantity of gluten exceeded the upper limit of 20 mg kg^-1. Out of the 10 contaminated products, eight (80%) were locally manufactured. Among these 10 products, eight (80%) were wheat-starch-based foods. Of the 40 brand names tested twice in 2014 and 2015, 15 (38%) showed significantly (p < .05) different gluten content between the 2 years. Using a food frequency questionnaire, exposure level to gluten through the contaminated products was evaluated among 15 celiac patients. Two patients reported consuming these products more than twice per week.

Allergenicity Assessment of Transgenic Wheat Lines In Silico

Agriculture biotechnology is a promising tool for developing varieties with enhanced quality and quantity. Transgenic proteins expressed by genetically modified (GM) food crops improve crop characteristics like nutritional value, taste, and texture, and endow plants with resistance against fungus, pests, and insects. Despite such potential benefits, there are concerns regarding possible adverse effects of GM crops on human health, animals and the environment. Among the proposed guidelines for GM food safety testing-the weight-of-evidence approach proposed by the Codex Alimentarius Commission (ALINORM 03/34A) is the most recent. Till date, several transgenic wheat lines have been developed and research is underway for further improvement. However, GM wheat is not being grown or consumed in any part of the world. In the present study, in silico tools were employed for safety testing of eight transgenes used for the development of transgenic wheat lines. Among the genes studied, none of them shared sequence homology with the reported allergens and may be safe for use in genetic engineering. In conclusion, gene selection for developing transgenic wheat lines should be done with utmost care to ensure its safety for feed and fodder.

Wheat-dependent exercise-induced anaphylaxis

Wheat-dependent exercise-induced anaphylaxis (WDEIA) is a rare, but potentially severe food allergy exclusively occurring when wheat ingestion is accompanied by augmenting cofactors. It is clinically characterized by anaphylactic reactions ranging from urticaria and angioedema to dyspnoea, hypotension, collapse, and shock. WDEIA usually develops after ingestion of wheat products followed by physical exercise. Other cofactors are acetylsalicylic acid and other non-steroidal anti-inflammatory drugs, alcohol, and infections. The precise mechanisms of WDEIA remain unclear; exercise and other cofactors might increase gastrointestinal allergen permeability and osmolality, redistribute blood flow, or lower the threshold for IgE-mediated mast cell degranulation. Among wheat proteins, ω5-gliadin and high-molecular-weight glutenin subunits have been reported to be the major allergens. In some patients, WDEIA has been discussed to be caused by epicutaneous sensitization with hydrolysed wheat gluten included in cosmetics. Diagnosis is made based on the patient's history in combination with allergy skin testing, determination of wheat-specific IgE serum antibodies, basophil activation test, histamine release test, and/or exercise challenge test. Acute treatment includes application of adrenaline or antihistamines. The most reliable prophylaxis of WDEIA is a gluten-free diet. In less severe cases, a strict limitation of wheat ingestion before exercise and avoidance of other cofactors may be sufficient.

Exercise-induced bronchoconstriction update-2016

The first practice parameter on exercise-induced bronchoconstriction (EIB) was published in 2010. This updated practice parameter was prepared 5 years later. In the ensuing years, there has been increased understanding of the pathogenesis of EIB and improved diagnosis of this disorder by using objective testing. At the time of this publication, observations included the following: dry powder mannitol for inhalation as a bronchial provocation test is FDA approved however not currently available in the United States; if baseline pulmonary function test results are normal to near normal (before and after bronchodilator) in a person with suspected EIB, then further testing should be performed by using standardized exercise challenge or eucapnic voluntary hyperpnea (EVH); and the efficacy of nonpharmaceutical interventions (omega-3 fatty acids) has been challenged. The workgroup preparing this practice parameter updated contemporary practice guidelines based on a current systematic literature review. The group obtained supplementary literature and consensus expert opinions when the published literature was insufficient. A search of the medical literature on PubMed was conducted, and search terms included pathogenesis, diagnosis, differential diagnosis, and therapy (both pharmaceutical and nonpharmaceutical) of exercise-induced bronchoconstriction or exercise-induced asthma (which is no longer a preferred term); asthma; and exercise and asthma. References assessed as relevant to the topic were evaluated to search for additional relevant references. Published clinical studies were appraised by category of evidence and used to document the strength of the recommendation. The parameter was then evaluated by Joint Task Force reviewers and then by reviewers assigned by the parent organizations, as well as the general membership. Based on this process, the parameter can be characterized as an evidence- and consensus-based document.

Cofactors in allergic reactions to food: physical exercise and alcohol are the most important

Introduction

Involvement of cofactors, like physical exercise, alcohol consumption and use of several types of medication, are associated with more severe food allergic symptoms. However, there is limited evidence on how often cofactors play a role in food allergic reactions. The study aimed to get more insight into the frequency of exposure to cofactors and how often cofactors are associated with more severe symptoms in food allergic patients.

Methods

A questionnaire was completed by patients visiting the Allergology outpatient clinic. Patients with food allergy were included. Outcome measures were the frequency of medication use of medication groups that might act as cofactor and the frequency that physical exercise, alcohol consumption and use of analgesics are associated with more severe food allergic symptoms.

Results

Four hundred ninety‐six patients were included in the study. The frequency with which patients used one or more types of medication that might act as cofactors was 7.7%: antacids/acid neutralizing medication (5%), NSAIDs (2%), beta blockers (0.6%), angiotensin‐converting enzyme inhibitors (0.6%), and angiotensin receptor blockers (0.2%). Of all patients, 13% reported more severe symptoms to food after involvement of one or more of the cofactors: physical exercise (10%), alcohol consumption (5%), and use of analgesics (0.6%). Sixty‐five percent did not know if these cofactors caused more severe symptoms; 22% reported that these cofactors had no effect.

Conclusions

Only a small percentage of patients (7.7%) used medication that might aggravate food allergic reactions. Physical exercise and alcohol consumption were the most frequently reported cofactors, but occurring still in only 10% or less.

Assessment of the Allergenic Potential of Transgenic Wheat (Triticum aestivum) with Reduced Levels of ω5-Gliadins, the Major Sensitizing Allergen in Wheat-Dependent Exercise-Induced Anaphylaxis

The ω5-gliadins are the major sensitizing allergens in wheat-dependent exercise-induced anaphylaxis (WDEIA). In this study, two-dimensional immunoblot analysis was used to assess the allergenic potential of two transgenic wheat lines in which ω5-gliadin genes were silenced by RNA interference. Sera from 7 of 11 WDEIA patients showed greatly reduced levels of immunoglobulin E (IgE) reactivity to ω5-gliadins in both transgenic lines. However, these sera also showed low levels of reactivity to other gluten proteins. Sera from three patients showed the greatest reactivity to proteins other than ω5-gliadins, either high-molecular-weight glutenin subunits (HMW-GSs), α-gliadins, or non-gluten proteins. The complexity of immunological responses among these patients suggests that flour from the transgenic lines would not be suitable for individuals already diagnosed with WDEIA. However, the introduction of wheat lacking ω5-gliadins could reduce the number of people sensitized to these proteins and thereby decrease the overall incidence of this serious food allergy.

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, cow's 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, cow's milk, wheat, shrimp, and peanut.

Study on the Immunoreactivity of Triticum monococcum (Einkorn) Wheat in Patients with Wheat-Dependent Exercise-Induced Anaphylaxis for the Production of Hypoallergenic Foods

Wheat [Triticum aestivum (T.a.)] ingestion can cause a specific allergic reaction, which is called wheat-dependent exercise-induced anaphylaxis (WDEIA). The major allergen involved is ω-5 gliadin, a gluten protein coded by genes located on the B genome. Our aim was to study the immunoreactivity of proteins in Triticum monococcum (einkorn, T.m.), a diploid ancestral wheat lacking B chromosomes, for possible use in the production of hypoallergenic foods. A total of 14 patients with a clear history of WDEIA and specific immunoglobulin E (IgE) to ω-5 gliadin were enrolled. Skin prick test (SPT) with a commercial wheat extract and an in-house T.a. gluten diagnostic solution tested positive for 43 and 100% of the cases, respectively. No reactivity in patients tested with solutions prepared from four T.m. accessions was observed. The immunoblotting of T.m. gluten proteins performed with the sera of patients showed different IgE-binding profiles with respect to T.a., confirming the absence of ω-5 gliadin. A general lower immunoreactivity of T.m. gluten proteins with scarce cross-reactivity to ω-5 gliadin epitopes was assessed by an enzyme-linked immunosorbent assay (ELISA). Given the absence of reactivity by SPT and the limited cross-reactivity with ω-5 gliadin, T.m. might represent a potential candidate in the production of hypoallergenic bakery products for patients sensitized to ω-5 gliadin. Further analyses need to be carried out regarding its safety.

Differential Expression of Durum Wheat Gluten Proteome under Water Stress during Grain Filling

Environmental stress during grain filling may affect wheat protein composition, thus influencing its final quality. A proteomic approach was used to evaluate changes in storage protein composition under water stress of two Italian durum wheat (Triticum turgidum ssp. durum) cultivars, Ciccio and Svevo. The high-molecular-weight glutenin region increased progressively in both cultivars and under two water regimens. The L48-35 region, corresponding to low-molecular-weight (LMW) glutenin subunits, increased slightly during grain development and decreased under water stress in both cultivars. In particular, an s-type LMW related to superior technological quality was down-expressed in the early-mid period in Svevo and in the mid-late period in Ciccio. Finally, the L<35 region, corresponding to gliadin-like proteins, decreased slightly during grain development and increased under stress in both cultivars. Several α-gliadins, associated with immunological potential, increased their expression under water stress, especially in Svevo in the early-mid stage of grain filling.

Food dependant exercise induced anaphylaxis a retrospective study from 2 allergy clinics in Colombo, Sri Lanka

The aetiology of anaphylaxis ranges from food, insect venom, drugs and various chemicals. Some individuals do not develop anaphylaxis with the offending agent unless ingestion is related temporally to physical exertion, namely food dependent exercise induced anaphylaxis (FDEIA). The foods implicated are wheat, soya, peanut, milk and sea food. A retrospective study on patients with FDEIA from two Allergy clinics in Sri Lanka from 2011 to 2015 is reported. Patients were selected who fulfilled the following criteria: clinical diagnosis of anaphylaxis according to the World Allergy Organization (WAO) criteria, where the onset of symptoms was during exertion, within 4 h of ingesting a food, the ability to eat the implicated food independent of exercise, or exercise safely, if the food was not ingested in the preceding 4 h and an in vitro (ImmunoCap serum IgE to the food) or in vivo (skin prick test) test indicating evidence of sensitivity to the food. There were 19 patients (12 males: 7 females). The ages ranged from 9 to 45 (mean 22.9, median 19 years). Eight patients (42.1%) were in the 9-16 age group. Those below 16 years had a male:female ratio of 3:5, while for those above 16 years it was 9:2. Wheat was the only food implicated in FDEIA in all patients and was confirmed by skin prick testing, or by ImmunoCap specific IgE to wheat or ω - 5 gliadin. All patients had urticaria, while 5/19 (26.3%) had angioedema of the lips. Fifteen patients (78.9%) had shortness of breath or wheezing, while 8 (42.1%) had lost consciousness. Nine patients (47. 3%) had hypotension. Fourteen (73.6%) of our patients had severe reactions, with loss of consciousness or hypotension, while 5 (26.3%) had symptoms related to the gastrointestinal tract. One patient developed anaphylaxis on two occasions following inhalation of ganja, a local cannabis derivative along with the ingestion of wheat and exertion. Wheat is the main food implicated in FDEIA in Sri Lanka. A local cannabis derivative, ganja has been implicated as a cofactor for the first time.

Celiac disease

This review will focus on the pathogenesis, clinical manifestations, diagnosis, and management of celiac disease (CD). Given an increasing awareness of gluten-related disorders, medical professionals of all varieties are encountering patients with a diagnosis of CD or who are thought to have food intolerance to gluten. The prevalence of CD among the general population is estimated to be 1% in Western nations, and there is growing evidence for underdiagnosis of the disease, especially in non-Western nations that were traditionally believed to be unaffected. The development of serologic markers specific to CD has revolutionized the ability both to diagnose and monitor patients with the disease. Additionally, understanding of the clinical presentations of CD has undergone a major shift over the past half century. Although it is well understood that CD develops in genetically predisposed subjects exposed to gluten, the extent of other environmental factors in the pathogenesis of the disease is an area of continued research. Currently, the main therapeutic intervention for CD is a gluten-free diet; however, novel nondietary agents are under active investigation. Future areas of research should also help us understand the relationship of CD to other gluten-related disorders.

Genome-, Transcriptome- and Proteome-Wide Analyses of the Gliadin Gene Families in Triticum urartu

Gliadins are the major components of storage proteins in wheat grains, and they play an essential role in the dough extensibility and nutritional quality of flour. Because of the large number of the gliadin family members, the high level of sequence identity, and the lack of abundant genomic data for Triticum species, identifying the full complement of gliadin family genes in hexaploid wheat remains challenging. Triticum urartu is a wild diploid wheat species and considered the A-genome donor of polyploid wheat species. The accession PI428198 (G1812) was chosen to determine the complete composition of the gliadin gene families in the wheat A-genome using the available draft genome. Using a PCR-based cloning strategy for genomic DNA and mRNA as well as a bioinformatics analysis of genomic sequence data, 28 gliadin genes were characterized. Of these genes, 23 were α-gliadin genes, three were γ-gliadin genes and two were ω-gliadin genes. An RNA sequencing (RNA-Seq) survey of the dynamic expression patterns of gliadin genes revealed that their synthesis in immature grains began prior to 10 days post-anthesis (DPA), peaked at 15 DPA and gradually decreased at 20 DPA. The accumulation of proteins encoded by 16 of the expressed gliadin genes was further verified and quantified using proteomic methods. The phylogenetic analysis demonstrated that the homologs of these α-gliadin genes were present in tetraploid and hexaploid wheat, which was consistent with T. urartu being the A-genome progenitor species. This study presents a systematic investigation of the gliadin gene families in T. urartu that spans the genome, transcriptome and proteome, and it provides new information to better understand the molecular structure, expression profiles and evolution of the gliadin genes in T. urartu and common wheat.

A Novel Multipeptide Microarray for the Specific and Sensitive Mapping of Linear IgE-Binding Epitopes of Food Allergens

BACKGROUND

The identification of B-cell epitopes of food allergens can possibly lead to novel diagnostic tools and therapeutic reagents for food allergy. We sought to develop a flexible, low-tech, cost-effective and reproducible multipeptide microarray for the research environment to enable large-scale screening of IgE epitopes of food allergens.

METHODS

Overlapping peptides (15-mer, 4 amino acid offset) covering the primary sequence of either peanut allergen Ara h 1 or all 3 subunits of the soybean allergen Gly m 5 were simultaneously synthesized in-house on a porous cellulose matrix. Identical peptide microarrays created with up to 384 duplicate peptide-cellulose microspots each were investigated for specificity and sensitivity in IgE immunodetection and in direct experimental comparison to the formerly established SPOT™ membrane technique.

RESULTS

The in-house microarray identified with 98% reproducibility the same IgE-binding peptides as the SPOT™ membrane technique. Additional IgE-binding peptides were identified using the microarray. While the sensitivity was increased between 2- and 20-fold, the amount of human serum required was reduced by at least two thirds over the SPOT™ membrane technique using the microarray. After subtraction of the potential background, we did not observe non-specific binding to the presented peptides on microarray.

CONCLUSIONS

The novel peptide microarray allows simple and cost-effective screening for potential epitopes of large allergenic legume seed storage proteins, and it could be adapted for other food allergens as well, to study allergenic epitopes at the individual subject level in large paediatric and adult study groups of food allergic subjects.

Patterns of suspected wheat-related allergy: a retrospective single-centre case note review in 156 patients

Background

Allergy to wheat can present clinically in different forms: Sensitization to ingested wheat via the gastrointestinal tract can cause traditional food allergy or in combination with exercise, Wheat-Dependent Exercise-Induced Anaphylaxis (WDEIA). Sensitization to inhaled wheat flour may lead to occupational rhinitis and/or asthma.

Methods

We retrospectively reviewed the case notes of 156 patients (age 0.7 – 73.3 years) with a case history of wheat allergy. The population was divided into three groups, 1: Wheat allergy elicited by ingestion, 2: By inhalation and 3: WDEIA. All patients were examined with detailed case history, specific IgE (sIgE), Skin Prick Test (SPT) and wheat challenge (nasal or oral ± exercise). Details of the case history were extracted from the patients´ case records.

Results

Group 1: Twenty one of 95 patients were challenge positive (15 children, 6 adults). All children had atopic dermatitis, and most (13/15) outgrew their wheat allergy. Most children (13/15) had other food allergies. Challenge positive patients showed significantly higher levels of sIgE to wheat and significantly more were SPT positive than challenge negative.

Group 2: Eleven out of 13 adults with occupational asthma or rhinitis were challenge positive. None outgrew their allergy. Seven had positive sIgE and 10 had positive SPT to wheat.

Group 3: Ten of 48 (adolescent/adults) were positive when challenged during exercise. Challenge positive patients showed significantly higher levels of sIgE to ω-5-gliadin. The natural course is presently unknown.

Conclusion

Wheat allergy can manifest in different disease entities, rendering a detailed case history and challenge mandatory. Patient age, occupation, concomitant allergies (food or inhalant) and atopic dermatitis are important factors for evaluation.

Biochemical, biophysical and IgE-epitope characterization of the wheat food allergen, Tri a 37

Wheat is an important staple food and potent allergen source. Recently, we isolated a cDNA coding for wheat alpha-purothionin which is recognized by wheat food allergic patients at risk for severe wheat-induced allergy. The purpose of the present study was the biochemical, biophysical and IgE epitope characterization of recombinant alpha-purothionin. Synthetic genes coding for alpha-purothionin were expressed in a prokaryotic system using Escherichia coli and in a eukaryotic expression system based on baculovirus-infected Sf9-insect cells. Recombinant proteins were purified and characterized by SDS-PAGE, mass spectrometry, circular dichroism, chemical cross-linking and size exclusion chromatography. Five overlapping peptid were synthesized for epitope mapping. Alpha-purothionin-specific rabbit antibodies were raised to perform IgE-inhibition experiments and to study the resistance to digestion. The IgE reactivity of the proteins and peptides from ten wheat food allergic patients was studied in non-denaturing RAST-based binding assays. Alpha-purothionin was expressed in the prokaryotic (EcTri a 37) and in the eukaryotic system (BvTri a 37) as a soluble and monomeric protein. However, circular dichroism analysis revealed that EcTri a 37 was unfolded whereas BvTri a 37 was a folded protein. Both proteins showed comparable IgE-reactivity and the epitope mapping revealed the presence of sequential IgE epitopes in the N-terminal basic thionin domain (peptide1:KSCCRSTLGRNCYNLCRARGAQKLCAGVCR) and in the C-terminal acidic extension domain (peptide3:KGFPKLALESNSDEPDTIEYCNLGCRSSVC, peptide4:CNLGCRSSVCDYMVNAAADDEEMKLYVEN). Natural Tri a 37 was digested under gastric conditions but resistant to duodenal digestion. Immunization with EcTri a 37 induced IgG antibodies which recognized similar epitopes as IgE antibodies from allergic patients and inhibited allergic patients' IgE binding. Reactivity to Tri a 37 does not require a folded protein and the presence of sequential IgE epitopes indicates that sensitization to alpha-purothionin occurs via the gut. Both allergens can be used for in-vitro diagnosis of wheat food allergy. The induction of blocking IgG antibodies suggests the usefulness for immunotherapy.

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.

Using a gluten oral food challenge protocol to improve diagnosis of wheat-dependent exercise-induced anaphylaxis

BACKGROUND

Oral wheat plus cofactors challenge tests in patients with wheat-dependent exercise-induced anaphylaxis (WDEIA) produce unreliable results.

OBJECTIVE

We sought to confirm WDEIA diagnosis by using oral gluten flour plus cofactors challenge, to determine the amount of gluten required to elicit symptoms, and to correlate these results with plasma gliadin levels, gastrointestinal permeability, and allergologic parameters.

METHODS

Sixteen of 34 patients with a history of WDEIA and ω5-gliadin IgE underwent prospective oral challenge tests with gluten with or without cofactors until objective symptoms developed. Gluten reaction threshold levels, plasma gliadin concentrations, gastrointestinal permeability, sensitivities and specificities for skin prick tests, and specific IgE levels were ascertained in patients and 38 control subjects.

RESULTS

In 16 of 16 patients (8 female and 8 male patients; age, 23-76 years), WDEIA was confirmed by challenges with gluten alone (n = 4) or gluten plus cofactors (n = 12), including 4 patients with previous negative wheat challenge results. Higher gluten doses or acetylsalicylic acid (ASA) plus alcohol instead of physical exercise were cofactors in 2 retested patients. The cofactors ASA plus alcohol and exercise increased plasma gliadin levels (P < .03). Positive challenge results developed after a variable period of time at peak or when the plateau plasma gliadin level was attained. Positive plasma gliadin threshold levels differed by greater than 100-fold and ranged from 15 to 2111 pg/mL (median, 628 pg/mL). The clinical history, IgE gliadin level, and baseline gastrointestinal level were not predictive of the outcomes of the challenge tests. The challenge-confirmed sensitivity and specificity of gluten skin prick tests was 100% and 96%, respectively.

CONCLUSION

Oral challenge with gluten alone or along with ASA and alcohol is a sensitive and specific test for the diagnosis of WDEIA. Exercise is not an essential trigger for the onset of symptoms in patients with WDEIA.