IgE binding to soluble and insoluble wheat flour proteins in atopic and non-atopic patients suffering from gastrointestinal symptoms after wheat ingestion

Wine Fining with Plant Proteins

Fining treatments involve the addition of a substance or a mixture to wine, and are generally carried out in order to clarify, stabilize or modify the wine’s organoleptic characteristics. Usually these fining agents will bind the target compound(s) to form insoluble aggregates that are subsequently removed from the wine. The main reasons to perform wine fining treatments are to carry out wine clarification, stabilization and to remove phenolic compounds imparting unwanted sensory characteristics on the wine, which is an operation that often relies on the use of animal proteins, such as casein, gelatin, egg and fish proteins. However, due to the allergenic potential of these animal proteins, there is an increasing interest in developing alternative solutions including the use of fining proteins extracted from plants (e.g., proteins from cereals, grape seeds, potatoes, legumes, etc.), and non-proteinaceous plant-based substances (e.g., cell wall polysaccharides and pomace materials). In this article, the state of the art alternative fining agents of plant origins are reviewed for the first time, including considerations of their organoleptic and technological effects on wine, and of the allergenic risks that they can pose for consumers.

Wheat amylase-trypsin inhibitors exacerbate intestinal and airway allergic immune responses in humanized mice

BACKGROUND

Amylase-trypsin inhibitors (ATIs) in wheat and related cereals are potent activators of myeloid innate immune cells via engagement of TLR4. Furthermore, ATIs have been shown to serve as adjuvants in experimental intestinal inflammatory diseases.

OBJECTIVE

The aim of this study was to analyze whether ATIs are also modifiers of allergic inflammation.

METHODS

Therefore, CD4⁺ T cells from donors sensitized to grass or birch pollen were stimulated with autologous allergen-pulsed dendritic cells in the presence or absence of ATIs or the control storage protein zein from corn. To analyze allergen-induced gut and lung inflammation, immunodeficient mice were engrafted with PBMCs from these allergic donors plus the respective allergen, and fed with selected diets. Three weeks later, inflammation was induced by rectal or intranasal allergen challenge and monitored by mini endoscopy or airway hyperreactivity, respectively.

RESULTS

Allergen-specific T-cell proliferation and cytokine production was significantly exacerbated by ATIs and not by zein. In vivo, allergen-specific human IgE level was strongly elevated in sera of mice receiving an ATI-containing diet compared with mice that were fed gluten-free and thus ATI-free diet. Importantly, allergen-induced IgE-dependent colitis and airway hyperreactivity were also enhanced in ATI-fed mice. Gut inflammation was further increased in mice receiving an additional ATI injection and even detectable in the absence of the aeroallergen, whereas zein had no such effect. Injection of anti-human TLR4 mAbs or the anti-human IgE mAb omalizumab completely abolished ATI-induced allergic inflammation.

CONCLUSIONS

These results underline that wheat ATIs are important nutritional activators and adjuvants of allergy, which might be exploited for nutritional therapeutic strategies.

The Role of Diet in the Treatment of Irritable Bowel Syndrome: A Systematic Review

Irritable bowel syndrome (IBS) is a multifaceted illness involving maladaptive shifts in the gut microbiota that affect the enteric nervous and immune systems, mucosal barrier function, the balance of neurotransmitters and hormones, and emotional well-being. There is abundant evidence indicating that certain foods elicit symptoms in IBS. Numerous elimination-type diets have been shown to alleviate symptoms. However, among these, the most controversial is a group of foods called fructo, oligo-, di-, and monosaccharides and polyols (FODMAPs). This paper reviews the role of diet and systematically analyze the literature for the role of FODMAPs in IBS.

Thermal treatment reduces gliadin recognition by IgE, but a subsequent digestion and epithelial crossing permits recovery

Wheat is one of the most important crops in the world in terms of human nutrition. With regards to health, some individuals exhibit wheat-related disorders such as food allergy to wheat (FAW). In this disorder, gluten is involved, particularly the gliadins which are among the main proteins responsible for FAW. Food processing, as well as digestibility and intestinal transport are key factors to consider since they may affect the allergenic potential of food allergens. Wheat is always consumed after heat processing and this step may impact epitope accessibility by inducing aggregation and may irreversibly destroy conformational epitopes. Our aim was to investigate the effects of heating and digestion on the structure of well-known allergens (total gliadins and α-gliadins) and their capacity to maintain their allergenic potential after crossing an intestinal barrier. The sizes of the processed (heated and heated/digested) proteins were characterized by laser light scattering and chromatographic reverse phase. The IgE-binding capacities of native and processed proteins were checked using a dot blot with sera from wheat allergenic patients. Furthermore, the abilities of these samples to cross the intestinal barrier and to induce mast cell degranulation were investigated by combining two in vitro cellular models, Caco-2 and RBL-SX38. The heat treatment of total gliadins and α-gliadins induced the production of large aggregates that were hardly recognized by IgE of patients in dot-blot. However, after limited pepsin hydrolysis, the epitopes were unmasked, and they were able to bind IgE again. Native proteins (gliadins and α-type) and processed forms were able to cross the Caco-2 cells in small amount. Permeability studies revealed the capacity of α-gliadins to increase paracellular permeability. In the RBL assay, the total native gliadins were able to trigger cell degranulation, but none of their processed forms. However after crossing the CaCo-2 monolayer, processed gliadins recovered their degranulation capacity to a certain extent. Total native gliadins remained the best allergenic form compared to α-type.

The Effect of Wheat Allergy on the Course of Atopic Eczema in Patients over 14 Years of Age

Few studies concerning the importance of wheat allergy affecting the course of atopic eczema in adolescents and adult patients exist. Aim: The evaluation if wheat allergy can deteriorate the course of atopic eczema. Follow-up of patients with confirmed food allergy to wheat. Method: Altogether 179 persons suffering from atopic eczema were included in the study: 51 men and 128 women entered the study with an average age of 26.2 (s.d. 9.5 years) Dermatological and allergological examinations were performed, including skin prick tests, atopy patch tests, and specific serum IgE for wheat, open exposure test and double-blind, placebo-controlled food challenge test with wheat flour. Results: Wheat allergy affecting the coures of atopic eczema was confirmed in eight patients (4.5%) out of 179 patients enrolled in this study by double-blind, placebo controlled food challenge test. The course of atopic eczema showed a positive trend in patients with confirmed food allergy at 3, 6, 9, 12 month follow-up (statistical evaluation with paired t-test) after the elimination of wheat flour. Conclusion: Wheat allergy may play an important role in the worsening of atopic eczema (acting as a triggering exacerbating factor) only in a minority of adolescents and adult patients (4.5% in our study). The diagnostic methods (skin prick test, specific IgE, atopy patch test, history) cannot be used as separated tests for the determination of food allergy to wheat in patients with atopic eczema.Open exposure tests and double-blind, placebo-controlled food challenge should be used for the confirmation of wheat allergy affecting the course of atopic eczema.

Wheat protein recognition pattern in tolerant and allergic children

BACKGROUND

Wheat is one of the most common food allergens in early childhood. In contrast to other food allergies, wheat-specific IgE correlates badly with clinical symptoms and relevant components have been identified mostly for wheat-depended exercise-induced anaphylaxis. Moreover, a high percentage of patients present with immediate type symptoms but wheat-specific IgE cannot be detected with commercial available systems.

OBJECTIVE

We addressed the question whether the IgE recognition pattern between wheat allergic (WA) and clinically tolerant (WT) children differs in order to identify individual proteins useful for component-resolved diagnostics.

METHODS

Sera of 106 children with suspected wheat allergy, of whom 44 children had clinical relevant wheat allergy and 62 were tolerant upon oral food challenge, were analyzed for wheat-specific IgE using the ImmunoCap system as well as immunoblots against water and salt soluble, and water-insoluble protein fractions. 40 randomly selected sera were analyzed for specific IgE to ω5-gliadin.

RESULTS

Sixty-three percent of the WT and 86% of the WA children were sensitized to wheat with >0.35 kUA /l in ImmunoCAP analysis. We could confirm the role of α-, ß-, γ-, and ω-gliadins, and LMW glutenin subunits as major allergens and found also IgE binding to a broad spectrum of water- and salt-soluble protein bands. It is of great importance that wheat allergic and tolerant patients showed IgE binding to the same protein bands. WT and WA did not significantly differ in levels of ω5-gliadin-specific IgE.

CONCLUSIONS & CLINICAL RELEVANCE

Children with challenge proven clinical relevant food allergy and tolerant ones had a similar spectrum of IgE binding to the same protein bands. These findings imply that component-resolved diagnostics might not be helpful in the diagnostic work-up of wheat allergy.

Clinical presentation, allergens, and management of wheat allergy

IgE-mediated allergy to wheat proteins can be caused by exposure through ingestion, inhalation, or skin/mucosal contact, and can affect various populations and age groups. Respiratory allergy to wheat proteins is commonly observed in adult patients occupationally exposed to flour, whereas wheat food allergy is more common in children. Wheat allergy is of growing importance for patients with recurrent anaphylaxis, especially when exercise related. The diagnosis of wheat allergy relies on a consistent clinical history, skin prick testing with well-characterized extracts and specific IgE tests. The accuracy of wheat allergy diagnosis may be improved by measuring IgE responses to several wheat components. However, a high degree of heterogeneity has been found in the recognition pattern of allergens among patient groups with different clinical profiles, as well as within each group. Thus, oral provocation with wheat or the implicated cereal is the reference test for the definitive diagnosis of ingested wheat/cereal allergy.

Food allergy in irritable bowel syndrome: The case of non-celiac wheat sensitivity

Irritable bowel syndrome (IBS) is one of the most common gastrointestinal disorders, having a prevalence of 12%-30% in the general population. Most patients with IBS attribute their symptoms to adverse food reactions. We review the role of diet in the pathogenesis of IBS and the importance of dietary factors in the management of these patients. The MEDLINE electronic database (1966 to Jan 2015) was searched using the following keywords: "food", "diet", "food allergy", "food hypersensitivity", "food intolerance", "IBS", "epidemiology", "pathogenesis", "pathophysiology", "diagnosis", "treatment". We found 153 eligible papers; 80 were excluded because: not written in English, exclusive biochemical and experimental research, case reports, reviews, and research otherwise not relevant to our specific interest. We selected 73 papers: 43 original papers, 26 reviews and 4 letters to the editor. These papers focused on IBS pathogenesis, the association between IBS and atopy, and between IBS and food allergy, the relationship between IBS and non-celiac wheat sensitivity, the role of diet in IBS. Pending further scientific evidence, a cautious approach is advisable but the concept of food allergy should be included as a possible cause of IBS, and a dietary approach may have a place in the routine clinical management of IBS.

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.

Immunological characterization of the gluten fractions and their hydrolysates from wheat, rye and barley

Gluten proteins in wheat, rye and barley cause celiac disease, an autoimmune disorder of the small intestine, which affects approximately 1% of the world population. Gluten is comprised of prolamin and glutelin. Since avoidance of dietary gluten is the only option for celiac patients, a sensitive gluten detection and quantitation method is warranted. Most regulatory agencies have set a threshold of 20 ppm gluten in foods labeled gluten-free, based on the currently available ELISA methods. However, these methods may exhibit differences in gluten quantitation from different gluten-containing grains. In this study, prolamin and glutelin fractions were isolated from wheat, rye, barley, oats and corn. Intact and pepsin-trypsin (PT)-digested prolamin and glutelin fractions were used to assess their immunoreactivity and gluten recovery by three sandwich and two competitive ELISA kits. The Western blots revealed varied affinity of ELISA antibodies to gluten-containing grain proteins and no reactivity to oat and corn proteins. ELISA results showed considerable variation in gluten recoveries from both intact and PT-digested gluten fractions among different kits. Prolamin fractions showed higher gluten recovery compared to their respective glutelin fractions. Among prolamins, barley exhibited higher recovery compared to wheat and rye with most of the ELISA kits used. Hydrolysis resulted in reduced gluten recovery of most gluten fractions. These results suggest that the suitability of ELISA for accurate gluten quantitation is dependent upon various factors, such as grain source, antibody specificity, gluten proteins and the level of their hydrolysis in foods.

Irritable bowel syndrome: contemporary nutrition management strategies

Irritable bowel syndrome is a complex disorder whose pathophysiology involves alterations in the enteric microbiota, visceral hypersensitivity, gut immune/barrier function, hypothalamic-pituitary-adrenal axis regulation, neurotransmitters, stress response, psychological factors, and more. The importance of diet in the management of irritable bowel syndrome has taken center stage in recent times as the literature validates the relationship of certain foods with the provocation of symptoms. Likewise, a number of elimination dietary programs have been successful in alleviating irritable bowel syndrome symptoms. Knowledge of the dietary management strategies for irritable bowel syndrome will help guide nutritionists and healthcare practitioners to deliver optimal outcomes. This tutorial reviews the nutrition management strategies for irritable bowel syndrome.

Improvement of Digestibility, Reduction in Allergenicity, and Induction of Oral Tolerance of Wheat Gliadin by Deamidation

Wheat gliadin was deamidated by using a cation-exchange resin in the presence or absence of added cysteine, with the change in digestibility being measured. The allergenicity of the gliadin was evaluated by using sera from patients RAST-positive to wheat. Gliadin-specific IgE was measured after the gliadin had been orally administered to rats. The addition of cysteine before the treatment with a cation exchanger effectively increased the deamidation level of gliadin. Deamidated gliadin showed higher solubility than the undeamidated form. There was no difference in the peptic digestibility of the gliadin, whereas deamidation enhanced the pancreatic digestibility in vitro and the digestibility in the mouse stomach in vivo. Deamidation of gliadin reduced its reactivity toward the sera of patients with wheat allergy. Rats administered with deamidated gliadin showed suppressed elevation of the gliadin-specific IgE level.

Identification of rice proteins recognized by the IgE antibodies of patients with food allergies

Similarity among food allergens is a great problem affecting the specificity of diagnosis and treatment of allergic patients. We have observed that 80% of patients with food (including wheat) and pollen allergies have increased IgE antibodies against rice proteins. By immunoblotting, we documented that boiling decreased solubility and IgE reactivity of PBS-extracted rice and wheat proteins, yet in SDS extracts this reactivity was only slightly changed. The sera of patients highly positive on the IgE immunoblot and positive in basophil activation and skin prick test with boiled rice components were used for characterizing the IgE-binding proteins separated by 1D or 2D electrophoresis. Using mass spectrometry, we identified 22 rice SDS soluble proteins. Six of them were new thermostable potential rice allergens: glutelin C precursor, granule-bound starch synthase 1 protein, disulfide isomerase-like 1-1 protein, hypothetical protein OsI_13867, putative acid phosphatase precursor 1, and a protein encoded by locus Os02g0453600. All of the identified rice proteins differed from known wheat allergens, except proteins belonging to the α-amylase/trypsin inhibitor family. Furthermore, we would suggest that in patients with high IgE reactivity to wheat and rice components, the IgE immunoblot and skin prick test with boiled rice proteins could be beneficial before diet recommendation.

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.

Wheat allergy

PURPOSE OF REVIEW

This review describes the diverse clinical manifestations of IgE-mediated allergy to ingested wheat and summarizes recent advances in characterization of clinically significant allergens and diagnostic workup.

RECENT FINDINGS

Recent population-based studies have shown the prevalence of wheat allergy and sensitization more precisely than past studies among small populations and in hospital settings. Intensive research has demonstrated the diverse profile of both water/salt-soluble and insoluble allergens involved in clinical types of wheat allergies determined depending on the patient age, the sensitization route, and the protein state during the exposure. Consequently, some new allergens, including nonspecific lipid transfer protein (Tri a 14), have been identified. For diagnosis, the role of water/salt-insoluble gliadins, particularly omega-5 gliadin, a major allergen of wheat-dependent, exercise-induced anaphylaxis, was assessed as compared with the results of oral challenges. The mechanisms of eliciting anaphylactic symptoms by exercise in wheat-dependent, exercise-induced anaphylaxis were speculated upon; one is the allergenicity strengthened by activated tissue transglutaminase and another is the increased absorption of allergens through the gastrointestinal tract.

SUMMARY

Findings of the recent studies show potential for more precise diagnosis in each clinical type of wheat allergies.

Micro-arrayed wheat seed and grass pollen allergens for component-resolved diagnosis

BACKGROUND

Wheat is a potent allergen source and can cause baker's asthma, food and pollen allergy. The aim of the study was to develop an allergen micro-array for differential diagnosis of baker's asthma, wheat-induced food allergy and grass pollen allergy.

METHODS

We analysed the immunoglobulin-E reactivity profiles of patients suffering from baker's asthma, wheat-induced food allergy and grass pollen allergy to micro-arrayed recombinant wheat flour allergens and grass pollen allergens and compared these results with clinical results and diagnostic tests based on crude wheat flour, wheat pollen and grass pollen allergen extracts.

RESULTS

We identified recombinant wheat flour allergens, which are specifically recognized by patients suffering from baker's asthma, but not from patients with food allergy to wheat or pollen allergy. rPhl p 1 and rPhl p 5 were identified as marker allergens specific for grass pollen allergy. They can be used to replace grass pollen extracts for allergy diagnosis and to identify grass pollen allergic patients among patients suffering from baker's asthma and wheat-induced food allergy. Profilin was identified as a cross-reactive allergen recognized by patients suffering from baker's asthma, food and pollen allergy.

CONCLUSIONS

Our results indicate that it will be possible to design serological tests based on micro-arrayed recombinant wheat seed and grass pollen allergens for the discrimination of baker's asthma, wheat-induced food allergy and grass pollen allergy.

Salt-soluble proteins from wheat-derived foodstuffs show lower allergenic potency than those from raw flour

Salt-soluble proteins from wheat flour have been described as main allergens associated with both baker's asthma and food allergy. However, most studies have used raw flour as starting material, thus not considering potential changes in allergenic properties induced by the heat treatment and other industrial processing to produce wheat-derived foodstuffs. Salt extracts from different commercial wheat-derived products were obtained and their allergenic properties investigated by IgE-immunodetection, ELISA assays, and skin prick test. The IgE-binding capacity of salt-soluble proteins from commercial breads and cooked pastas was reduced around 50% compared with that of raw flour, the reduction being less dramatic in noncooked pastas and biscuits. Several wheat-derived foodstuffs showed major IgE-binding components of 20 and 35 kDa, identified as avenin-like and globulin proteins, respectively. These proteins, as well as most flour and bread salt-soluble proteins, were hydrolyzed when subjected to simulated gastrointestinal digestion. However, the digested products still exhibited a residual IgE-binding capacity. Therefore, processing of wheat flour to obtain derived foodstuffs decreases the IgE binding-capacity of the major salt-soluble wheat proteins. Moreover, simulated gastric fluid digestion further inactivates some heat-resistant IgE-binding proteins.

Proteomic analysis of wheat proteins recognized by IgE antibodies of allergic patients

Wheat belongs to six major food allergens inducing IgE-mediated hypersensitivity reaction manifesting as cutaneous, gastrointestinal, and respiratory symptoms. Although cereals are a staple food item in most diets, only a few wheat proteins causing hypersensitivity have been identified. To characterize wheat allergens, salt-soluble wheat extracts were separated by 1-DE and 2-DE and IgE-binding proteins were detected by immunoblotting using sera of patients with allergy to ingested wheat. Proteins, frequently recognized by IgE on 2-DE were analyzed by MALDI-TOF and QTOF and their spectrum was completed by 1-DE and LCQ(DECA) nLC-MS/MS IT technique. Using all three techniques we identified 19 potential wheat allergens such as alpha-amylase inhibitors, beta-amylase, profilin, serpin, beta-D-glucan exohydrolase, and 27K protein. Employing newly developed ELISA, levels of IgE Abs against Sulamit wheat extract and alpha-amylase inhibitors type 1 and 3 were quantified and shown to be significantly elevated in sera of allergic patients compared to those of healthy controls. The level of IgE Abs against alpha-amylase inhibitor type 3 was lower, slightly above the cut-off value in the majority of patients' sera. Our findings contribute to the identification of wheat allergens aimed to increase the specificity of serum IgE and cell activation diagnostic assays.

Discrepancies between the responses to skin prick test to food and respiratory antigens in two subtypes of patients with irritable bowel syndrome

AIM: To compare the response to skin prick tests (SPTs) to food antigens (FAs) and inhalant allergens (IAs) in patients with two subtypes of irritable bowel syndrome (IBS) and healthy controls.

METHODS: We compared the results of SPTs for IAs and FAs in 87 volunteers divided into three groups: diarrhea predominant IBS (D-IBS) GroupI(n = 19), constipation predominant IBS (C-IBS) Group II (n = 17), and normal controls Group III (n = 51).

RESULTS: Of the 285 tests (171 for FAs and 114 for IAs) performed in GroupIwe obtained 45 (26.3%) positive responses for FA and 23 (20.1%) for IA. Of the 153 tests for FA in Group II, we obtained 66 (20.1%) positive responses, and of the 102 tests for IA, we obtained 20 (19.6%) positive responses. Of the 459 tests for FA performed in Group III, we obtained 39 (84%) positive responses, and of the 306 for IA, we obtained 52 (16.9%) positive responses. The numbers of positive responses were not significantly different between the three groups, but in the D-IBS group, the number of SPT FA responses differed significantly from those for the other two groups (P < 0.01).

CONCLUSION: Despite the small number of cases studied, the higher reactivity to FAs in GroupIcompared to Groups II and III adds new information, and suggests the presence of a possible alteration in intestinal epithelial function.

Wheat IgE-mediated food allergy in European patients: alpha-amylase inhibitors, lipid transfer proteins and low-molecular-weight glutenins. Allergenic molecules recognized by double-blind, placebo-controlled food challenge

BACKGROUND

Three main problems hamper the identification of wheat food allergens: (1) lack of a standardized procedure for extracting all of the wheat protein fractions; (2) absence of double-blind, placebo-controlled food challenge studies that compare the allergenic profile of Osborne's three protein fractions in subjects with real wheat allergy, and (3) lack of data on the differences in IgE-binding capacity between raw and cooked wheat.

METHODS

Sera of 16 wheat-challenge-positive patients and 6 patients with wheat anaphylaxis, recruited from Italy, Denmark and Switzerland, were used for sodium dodecyl sulfate-polyacrylamide gel electrophoresis/immunoblotting of the three Osborne's protein fractions (albumin/globulin, gliadins and glutenins) of raw and cooked wheat. Thermal sensitivity of wheat lipid transfer protein (LTP) was investigated by spectroscopic approaches. IgE cross-reactivity between wheat and grass pollen was studied by blot inhibition.

RESULTS

The most important wheat allergens were the alpha-amylase/trypsin inhibitor subunits, which were present in all three protein fractions of raw and cooked wheat. Other important allergens were a 9-kDa LTP in the albumin/globulin fraction and several low-molecular-weight (LMW) glutenin subunits in the gluten fraction. All these allergens showed heat resistance and lack of cross-reactivity to grass pollen allergens. LTP was a major allergen only in Italian patients.

CONCLUSIONS

The alpha-amylase inhibitor was confirmed to be the most important wheat allergen in food allergy and to play a role in wheat-dependent exercise-induced anaphylaxis, too. Other important allergens were LTP and the LMW glutenin subunits.

New insights into the pathogenesis and pathophysiology of irritable bowel syndrome

The pathogenesis and pathophysiology of irritable bowel syndrome is complex and still incompletely known. Potential pathogenetic factors include genes, infectious events, psychological symptoms and other loosely defined environmental factors. Both alterations at the central and peripheral level are thought to contribute to the symptoms of irritable bowel syndrome, including psychosocial factors, abnormal gastrointestinal motility and secretion, and visceral hypersensitivity. Today irritable bowel syndrome is viewed upon as a disorder of dysregulation of the so-called brain-gut axis, involving abnormal function in the enteric, autonomic and/or central nervous systems, with peripheral abnormalities probably dominating in some patients and disturbed central processing of signals from the periphery in others. Lines of evidence also suggest that inflammation within the gastrointestinal tract may be of great importance in at least subgroups of irritable bowel syndrome patients. To conclude, a complex picture of the pathogenesis and pathophysiology of irritable bowel syndrome is emerging, with interactions between several different alterations resulting in the divergent symptom pattern in these patients.

Probiotic preparation has the capacity to hydrolyze proteins responsible for wheat allergy

This study was aimed at showing the capacity of probiotic VSL#3 to hydrolyze wheat flour allergens. Hydrolysis was investigated either by the use of baker's yeast bread treated with digestive enzymes and VSL#3, an experimental design that mimicked the activity of probiotics during gut colonization, or by the use of VSL#3 as a starter for dough fermentation, an experimental design that mimicked the predigestion of wheat flour proteins during food processing. Albumins, globulins, and gliadins extracted from wheat flour and chemically acidified and started dough and total proteins extracted from breads were analyzed by immunoblotting with pooled sera from patients with an allergy to wheat. Hydrolysis of wheat flour proteins was determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and two-dimensional electrophoresis (2DE). Mass spectrometry matrix-assisted laser desorption and ionization-time of flight was used to identify some immunoglobulin E (IgE)-binding proteins. As shown by immunoblotting with sera from allergic patients, several IgE-binding proteins persisted after treatment of baker's yeast bread by pepsin and pancreatin. The signal of all these IgE-binding proteins disappeared after further treatment by VSL#3. As shown by SDS-PAGE and related immunoblotting and 2DE analyses, when VSL#3 was used as a starter for bread making, it caused a marked degradation of wheat proteins, including some IgE-binding proteins such as the putative transcription factor APFI and wheat alpha-amylase inhibitors. Indeed, the IgE-binding profile of the bread manufactured by VSL#3 was largely different from that of baker's yeast bread. The IgE-binding proteins that persisted in the bread made with VSL#3 were completely degraded by pepsin and pancreatin.

Wheat allergy: a double-blind, placebo-controlled study in adults

BACKGROUND

Wheat is believed to be an uncommon cause of food allergy in adults; the number of studies that address IgE mediated wheat allergy in adults is all too few.

OBJECTIVE

Determine how many subjects with a history of wheat allergy have real allergy by double-blind, placebo-controlled food challenge; identify the symptoms manifested during the challenge; determine the lowest provocation dose; determine the performance characteristics of wheat skin prick test and specific IgE; identify subjects with real wheat allergy for potential immunoblotting studies.

METHODS

Patients underwent skin test with commercial wheat extract; specific wheat IgE was determined. Subjects were challenged with 25 g wheat. Subjects who were positive to raw wheat challenge underwent cooked wheat challenge.

RESULTS

Thirty-seven double-blind placebo-controlled wheat challenges were performed on 27 patients. A total of 13 of 27 (48%) patients had a positive result. Eleven subjects with positive raw wheat challenge underwent cooked wheat challenge: 10 were positive. The provocation dose range was 0.1 to 25 g. Twenty-seven percent of the subjects allergic to wheat had a provocation dose that was < or =1.6 g.

CONCLUSION

Wheat causes real food allergy in adults. More than a quarter of the patients allergic to wheat reacted to less than 1.6 g wheat. Specific IgE was more sensitive than skin test for wheat; however, specificity and predictive values were low for both tests. Thus, these tests should not be used to validate diagnosis of wheat allergy.

Review article: safe amounts of gluten for patients with wheat allergy or coeliac disease

For both wheat allergy and coeliac disease the dietary avoidance of wheat and other gluten-containing cereals is the only effective treatment. Estimation of the maximum tolerated amount of gluten for susceptible individuals would support effective management of their disease. Literature was reviewed to evaluate whether an upper limit for gluten content in food, which would be safe for sufferers from both diseases, could be identified. When setting gluten limits for coeliac disease sufferers, the overall potential daily intake should be considered, while for wheat allergy limits should be based on single servings. For coeliac disease sufferers this limit should lie between 10 and 100 mg daily intake. For wheat allergy, lowest eliciting doses for children lie in the lower milligram range, while for adults they are most significantly higher. Gliadins (part of the gluten proteins) not only trigger coeliac disease, but are also major allergens in wheat allergy. Therefore, measurement of gliadins with validated enzyme-linked immunosorbent assay methods provides an appropriate marker for assessing gluten and/or wheat protein contents in food. Available data suggest that a maximum gluten content for 'gluten-free' foods could be set, which protects both wheat allergy sufferers and coeliac patients.

Immunological functions of soy sauce: hypoallergenicity and antiallergic activity of soy sauce

Soy sauce is a traditional fermented seasoning of East Asian countries and is available throughout the world. In Japanese soy sauce (shoyu), soybeans and wheat are the two main raw materials, used in almost the same quantity. Proteins of the raw materials are completely degraded into peptides and amino acids by microbial proteolytic enzymes after fermentation, and no allergens of the raw materials are present in soy sauce. In contrast, polysaccharides originating from the cell wall of soybeans are resistant to enzymatic hydrolyses. These polysaccharides are present in soy sauce even after fermentation and termed shoyu polysaccharides (SPS). Soy sauce generally contains about 1% (w/v) SPS and SPS exhibit potent antiallergic activities in vitro and in vivo. Furthermore, an oral supplementation of SPS is an effective intervention for patients with allergic rhinitis in two double-blind placebo-controlled clinical studies. In conclusion, soy sauce would be a potentially promising seasoning for the treatment of allergic diseases through food because of its hypoallergenicity and antiallergic activity.

Gastrointestinal allergy in adults

The prevalence of food allergy reaches 3% in the adult population. Chronic gastrointestinal allergy is a rare entity: 4.2% of food allergies in adults, and represents 3.2% of all intestinal disorders. Non-specific symptoms are the rule but eosinophilic gastrointestinal disorders are the subject of much interest. Endoscopy and biopsies of the gastrointestinal tract help the differential diagnoses. Food allergy is suspected from the patient's history leading to skin tests and laboratory tests identifying a sensitization but allergy is only confirmed by standardized challenges or eviction diets over a sufficiently long period. New types of investigations coupling oral challenges to foods to gastroenterological techniques should be studied further.

Different profiles of wheat antigens are recognised by patients suffering from coeliac disease and IgE-mediated food allergy

BACKGROUND

Dietary intake of wheat can cause two distinct immunologically mediated diseases with severe gastrointestinal manifestations, coeliac disease (CD) and IgE-mediated food allergy. The pathomechanisms underlying these diseases are different, but the profile of the target antigens in wheat has not been compared for the two diseases.

METHODS

We compared IgA- and IgE-reactive antigens in wheat using sera from patients with coeliac disease (n = 35) and food allergy to wheat (n = 16) by one- and two-dimensional immunoblotting. Furthermore, the IgG subclass (IgG1-IgG4) reactivity to wheat antigens was studied by enzyme-linked immunosorbent assay.

RESULTS

IgA antibodies from CD patients and IgE antibodies from allergic patients recognised distinct profiles of wheat antigens. Furthermore, the IgG subclass responses to wheat antigens were different in CD and wheat-allergic patients.

CONCLUSION

This study thus demonstrates that wheat contains antigens/epitopes which are preferentially recognised by CD patients, whereas others elicit IgE-mediated food allergy. This finding suggests that the nature of a food antigen may influence the quality of the pathological immune response in the gut and has implications for the diagnosis and therapy of hypersensitivity to wheat.

Identification of IgE-binding epitopes on gliadins for patients with food allergy to wheat

BACKGROUND

Food allergy to wheat induces different symptoms as atopic eczema/dermatitis syndrome (AEDS), urticaria and more severe reactions as wheat-dependent exercise-induced anaphylaxis (WDEIA). Different gliadin classes are involved in this allergy but IgE-binding epitopes are known only on omega5-gliadins and for WDEIA cases.

OBJECTIVES

The aim of the study was to identify IgE-binding epitopes on several gliadin classes and for several patients with different symptoms and ages.

METHODS

Eleven sera were analysed by pepscan with overlapping synthetic peptides.

RESULTS

Sera from five patients with anaphylaxis, urticaria or WDEIA, displayed strong IgE-binding to sequential epitopes of the repetitive domains of alphabeta, gamma, omega2 or omega5-gliadins with two immunodominant epitopes on omega5-gliadin and a consensus motif of the type QQX1PX2QQ (X1 being L, F, S or I and X2 Q, E or G). One patient allergic to deamidated wheat proteins also had IgE to a repetitive peptide of gamma and omega2-gliadins of the type QPQQPFP. Sera from four patients with AEDS detected no linear epitopes on gliadins, despite the fact that they contained specific IgE to alpha, beta, gamma or omega-gliadins. One child with AEDS recognized cysteine-containing sequences in the nonrepetitive domains of alphabeta and gamma-gliadins.

CONCLUSION

B epitopes in wheat allergy were different from B epitopes of coeliac disease. Differences exist in IgE-binding epitopes between patients with food allergy to wheat. IgE from those suffering from WDEIA, anaphylaxis and urticaria detected sequential epitopes in the repetitive domain of gliadins whereas IgE from AEDS patients probably recognized conformational epitopes.

Adult food allergy

Adult food allergy is estimated at approximately 3.2% worldwide. The persistence of childhood food allergy is unusual, peanut allergies excepted. Once established in adults, food allergy is rarely cured. Factors favoring the acquisition of allergy could be sensitization to pollens, occupational sensitization by inhalation, drugs (such as tacrolimus), and sudden dietary changes. Severe anaphylaxis and oral allergy syndrome are frequent. The fatality risk is estimated at 1% in severe anaphylaxis. Risk factors for severe anaphylaxis are agents causing increased intestinal permeability, such as alcohol and aspirin. b-blockers, angiotensin-converting enzyme (ACE) inhibitors, and exercise are other factors. Gastrointestinal food allergy remains, to a large extent, undiagnosed in adults. Food allergens are mainly fruit and vegetable, related to pollen sensitizations, or to latex allergy. Wheat flour allergy is increasing. The diagnosis relies on prick skin tests, detection of specific IgEs, and standardized oral challenges. Strict avoidance diets are necessary. Specific immunotherapy to pollens may be efficient for cross-reactive food allergies.

IgE antibodies to omega-5 gliadin in children with wheat-induced anaphylaxis

BACKGROUND

Wheat can cause severe immunoglobulin E (IgE)-mediated systemic reactions including anaphylaxis but knowledge on relevant wheat allergens at the molecular level is scanty.

METHODS

Seven children (aged from 6 months to 13 years) experiencing from 2 to 10 anaphylactic reactions in a year after eating food-containing wheat were examined. Purified omega-5 gliadin was used as an allergen in IgE enzyme-linked immunosorbent assay (ELISA) and in skin prick testing (SPT). Wheat CAP radioallergosorbent test (RAST) and SPT were also examined.

RESULTS

All seven anaphylactic children, but none of 15 control subjects had IgE antibodies to omega-5 gliadin in ELISA. Five of the six tested anaphylactic children showed positive SPT to omega-5 and crude gliadin, and all seven had positive wheat CAP RAST and SPT. One child was challenged with wheat, which caused anaphylaxis. After adherence to a wheat-free diet four children remained symptomless and three experienced one to two anaphylactic reactions.

CONCLUSION

The present results show that wheat omega-5 gliadin is a major sensitizing allergen in children with wheat-induced anaphylaxis. They also suggest that omega-5 gliadin IgE ELISA could be used as a diagnostic test for this severe allergy.

Immunoglobulin E-reactivity of wheat-allergic subjects (baker's asthma, food allergy, wheat-dependent, exercise-induced anaphylaxis) to wheat protein fractions with different solubility and digestibility

Baker's asthma, food allergy to wheat, and wheat-dependent, exercise-induced anaphylaxis (WDEIA) are different clinical forms of wheat allergy. We investigated the correlation of solubility and digestion stability of wheat allergens with the IgE-reactivity patterns of different patient groups. Three wheat protein fractions were extracted according to their solubility: salt-soluble albumins and globulins, ethanol-soluble gliadins, and glutenins soluble only after treatment with detergents and reducing reagents. Sera from subjects with history of each variant of wheat allergy were characterized by CAP FEIA and immunoblotting. There was a high degree of heterogeneity of recognized allergens between the different subject groups as well as within these groups. However, subjects with WDEIA showed similar immunoglobulin E (IgE)-reactivity patterns to gliadins and especially to a 65 kDa protein. Subjects with baker's asthma as well as the food-allergic subjects had the most intense IgE-reactivity to the albumin/globulin fraction. The latter group additionally showed IgE-reactivity to the other fractions. Divergent results of immunoblotting and CAP-FEIA demonstrated that the detection of wheat-specific IgE highly depends on the applied method, thus the diagnostic tool must be carefully chosen. Most wheat allergens were rapidly digested as analyzed by determination of IgE-reactivity on immunoblots to wheat extracts after simulation of gastric and duodenal digestion. However, ethanol-soluble gliadins were stable to gastric enzymes and exhibit low solubility in gastric and duodenal fluids. Therefore, they are likely to be important in food allergy to wheat.

Clinical value and measurement of specific IgE

The diagnosis of human allergic diseases involves the combined use of a careful clinical history, physical examination, and in vitro and in vivo assay methods for the detection of IgE antibodies of defined allergen specificities. In vivo (skin testing) and in vitro (measurement of specific IgE in serum) techniques cannot be considered interchangeable, the former reflecting not only the presence of IgE but also mast cell integrity, vascular and neural responsiveness. Both techniques have similarities and differences, advantages and disadvantages. Recently introduced "second generation" immunoassays have continued to improve the analytical sensitivity and reproducibility thanks to automation and improved reagent quality. Quantitative assays may allow the use of specific clinical thresholds able to differentiate symptomatic from asymptomatic patients. False-negative and false-positive results should derive from lability of some major extracts, and from possible cross-reactivities, respectively. Characterization of allergens at a molecular and submolecular level and, where necessary, the use of recombinant allergens can reduce cross-reactions and further improve the quality of immunoassays.

Food allergy to wheat: identification of immunogloglin E and immunoglobulin G-binding proteins with sequential extracts and purified proteins from wheat flour

BACKGROUND

Cereal-associated allergy is particularly considered a serious problem, because cereals are essential in our daily diet. Wheat proteins are classified into albumins, globulins and prolamins (insoluble gliadins and glutenins).

OBJECTIVES

Our objectives were to study the involvement in food allergy to wheat of these different protein types by using purified fractions and to identify those binding IgE and IgG antibodies.

METHODS

Sera were obtained from 28 patients with food allergy to wheat. Albumins/globulins, gliadins and glutenins were obtained by sequential extraction based on differential solubility; alpha-, beta-, gamma- and omega-gliadins and low molecular weight (LMW) and high molecular weight (HMW) glutenin subunits were purified by chromatography. IgE binding to these extracts and fractions were analysed by radioallergosorbent test (RAST), and immunoblotting; IgG binding was detected by enzyme-linked immunosorbent assay (ELISA).

RESULTS

In RAST, 60% of sera were shown to have specific IgE antibodies against alpha-, beta-gliadins and LMW glutenin subunits, 55% to gamma-gliadins, 48% to omega-gliadins and 26% to HMW glutenins. Immunoblotting analysis confirmed results obtained in RAST concerning LMW and HMW glutenin subunits and showed that 67% of patients have IgE antibodies to the albumin/globulin fraction.

CONCLUSION

Results obtained in the different tests showed common features and in agreement with other studies indicated the presence of numerous allergens in food allergy to wheat; alpha-, beta-, gamma- and omega-gliadins, LMW glutenin subunits and some water/salt-soluble proteins appeared as major IgE binding allergens, whereas HMW glutenins were only minor allergens. The same type of antigenic profile against gliadins and glutenins was observed with IgG antibodies. Important sequence or structural homologies between the various gliadins and LMW glutenin subunits could certainly explain similarity of IgE binding to these proteins.

Characterization of allergenic food proteins for improved diagnostic methods

PURPOSE OF REVIEW

Diagnostic decision points for food allergen-specific serum IgE concentration and for skin prick test results have been established for several foods, reducing the requirement for food challenges in a number of patients. Many patients, however, still need to undergo oral food challenges because their food-specific IgE level is in the undefined range. In addition, diagnostic decision points could not be established for several foods. It appears that measurement of serum specific IgE concentrations to individual allergens is superior to determination of specific IgE to the crude food extract containing allergenic and nonallergenic proteins. This review will outline recent advantages in characterization of food allergens as well as the relevance of this knowledge for use in recently developed protein microarray technology.

RECENT FINDINGS

Protein microarrays have been developed to profile allergen-specific IgE antibodies from human serum with the advantage of screening hundreds of allergens in parallel using minute amounts of blood. This technology, however, requires prior knowledge of the proteins to be studied. The identification and characterization of clinically relevant allergens have increased dramatically within the last several years. Relevant new allergens have been identified, especially in tree nuts and seeds. Interestingly, most of these allergens belong to the same family of seed storage proteins. In addition, known food allergens have been further characterized and IgE-binding sites have been determined. Moreover, 'informative' peptides shown to be predictive for the persistence of food allergy have been identified.

SUMMARY

The combination of food allergen characterization and protein or peptide microarray technology will enable us to develop improved diagnostic tools in food allergy.

Update on wheat hypersensitivity

PURPOSE OF REVIEW

Wheat is among the six foods responsible for approximately 90% of food allergies in children, and in recent years wheat has been increasingly recognized as a cause of food-dependent, exercise-induced anaphylaxis. Wheat flour is an important cause of baker's asthma, a well-known occupational respiratory allergy to inhaled flour. This review outlines the diverse clinical manifestations of IgE-mediated wheat hypersensitivity and summarizes recent advances in characterization of clinically significant allergens.

RECENT FINDINGS

Only a few of the numerous wheat proteins recognized by IgE of sensitized individuals have been characterized at the molecular level. Characterized allergens causing baker's asthma include several water/salt-soluble wheat proteins, however sensitization patterns show a great degree of individual variation. The insoluble gliadins have been implicated in IgE-mediated allergy to ingested wheat, and omega-5 gliadin has been identified as a major allergen in wheat-dependent, exercise-induced anaphylaxis. The presence of IgE to purified omega-5 gliadin in children was highly predictive of immediate clinical symptoms on oral wheat challenge.

SUMMARY

Diagnostic skin prick and in-vitro tests measuring sensitization against water/salt-soluble wheat proteins have poor predictive values. Quantification of gliadin-specific IgE in serum or skin prick testing with gliadin could serve as an additional tool in the diagnostic work-up of allergy to ingested wheat.

Allergy to millet: another risk for atopic bird keepers

BACKGROUND

Millet has been reported to induce not very frequent but severe anaphylactic reactions following ingestion. Seven individuals who all kept cage birds experienced allergic reactions after ingestion of millet-containing food.

METHODS

We investigated the immunoglobulin E (IgE)-reactivity of these individuals to millet employing immunoblotting, RAST and skin prick tests. As the sensitization possibly occurred via the inhalant route we investigated millet-specific IgE levels of 16 additional sera from bird keepers with proven atopy, in retrospect.

RESULTS

All patients who had experienced reactions after ingestion of millet displayed millet-specific IgE. Sixty-three percent of the atopic bird keepers possessed millet-specific IgE. By means of immunoblotting three major allergens in millet extract were detected.

CONCLUSIONS

Our results indicate that millet plays an important role as inhalant allergen for atopic bird keepers. A sensitization to millet may subsequently also elicit food allergy.

Food allergy

Food allergy encompasses a range of disorders that result from adverse immune responses to dietary antigens. This group of conditions includes acute, potentially fatal reactions, and a host of chronic diseases that mainly affect the skin and gastrointestinal tract. Tools for diagnosis and management have not changed much in the past two decades, and include the clinical history, physical examination, tests for specific IgE antibody to suspected foods, elimination diets, oral food challenges, and provision of medications such as epinephrine for emergency treatment. However, much research in the past few years has enhanced our understanding of the clinical, epidemiological, and immunological aspects of these disorders. In this review I will discuss these advances and incorporate them into an improved diagnostic and management scheme. Additionally, emergent diagnostic, treatment, and prevention strategies are reviewed.