Buckwheat allergy

Elimination of zero-repeat subunit in allergenic seed protein 13S globulin using the novel allele GlbNB2 in common buckwheat (Fagopyrum esculentum Moench)

Common buckwheat (Fagopyrum esculentum Moench) seeds contain 13S globulin, the zero-repeat subunit of which is trypsin-resistant and allergenic. Here, its two novel alleles were analyzed for development of hypoallergenic plants. The GlbNC allele has a Miniature Inverted-repeat Transposable Element (MITE)-like insertion in the 4th exon. However, most of the insertion was spliced-out, resulting in accumulation of zero-repeat subunit in GlbNC homozygotes. Meanwhile, the GlbNB2 has a 164-bp insertion in the 3rd exon, resulting in no accumulation of zero-repeat subunit in GlbNB2 homozygotes (NB2_homo). Both the insertion sequences were predicted to form a hairpin-like structure, and that of GlbNB2 was more rigid than that of GlbNC. Trypsin digestion in NB2_homo showed that the α polypeptide of Met-rich subunit is also hard to digest, that is a next target to eliminate for hypoallergenic buckwheat development.

Insertion of ten amino acids into 13S globulin zero-repeat subunit improves trypsin digestibility in common buckwheat (Fagopyrum esculentum Moench) seeds

The 13S globulin zero-repeat subunit is resistant to trypsin and may have higher allergenicity than the 1-6 tandem repeat subunits in common buckwheat (Fagopyrum esculentum Moench). To explore alleles useful for lowering allergenicity, amplicon deep sequencing targeting the zero-repeat subunit gene was conducted in bulked genomic DNA from eight cultivars and landraces. The analysis identified a unique allele encoding a zero-repeat subunit with 10 amino acid insertion (10aa) at a position equivalent to the tandem repeat insertion. Prediction of its 3-D structure suggested that 10aa changes the β-hairpin structure in the non-10aa (native) subunit to a random coil, which is also found in 1- and 3- repeat subunits. Homozygotes of the 10aa allele were developed and showed that the 10aa subunit was more digestible than the native subunit. However, the 10aa subunit was still less digestible than the 1-6 repeat subunits, suggesting needs to explore unfunctional alleles.

Food protein-induced enterocolitis syndrome due to buckwheat: A case report

Buckwheat is a rare causative food for food protein-induced enterocolitis syndrome (FPIES). To date, it is unknown what laboratory data patients with FPIES caused by buckwheat show. We report a 4-year-old female with FPIES caused by buckwheat and the laboratory results. Skin prick, specific IgE antibody, and basophil activation tests were negative; however, the lymphocyte stimulation test (LST) revealed a 10.2-fold increase in activation compared with the negative control. In an open-label oral food challenge (OFC) of 80 g boiled buckwheat noodles, 3 hours after ingestion, vomiting occurred four times in a 2-hour duration. Therefore, we diagnosed the patient with FPIES caused by buckwheat. Her neutrophil count, C-reactive protein, and thymus and activation-regulated chemokine were elevated after the OFC. Moreover, the patient had a positive reaction to the LST, which may theoretically be useful in diagnosing non-immunoglobulin E-mediated gastrointestinal food allergies. FPIES caused by buckwheat is rare; however, we found that the same laboratory results were observed in a comparison of FPIES cases caused by other foods.

Tartary Buckwheat in Human Nutrition

Tartary buckwheat (Fagopyrum tataricum Gaertn.) originates in mountain areas of western China, and it is mainly cultivated in China, Bhutan, northern India, Nepal, and central Europe. Tartary buckwheat shows greater cold resistance than common buckwheat, and has traits for drought tolerance. Buckwheat can provide health benefits due to its contents of resistant starch, mineral elements, proteins, and in particular, phenolic substances, which prevent the effects of several chronic human diseases, including hypertension, obesity, cardiovascular diseases, and gallstone formation. The contents of the flavonoids rutin and quercetin are very variable among Tartary buckwheat samples from different origins and parts of the plants. Quercetin is formed after the degradation of rutin by the Tartary buckwheat enzyme rutinosidase, which mainly occurs after grain milling during mixing of the flour with water. High temperature treatments of wet Tartary buckwheat material prevent the conversion of rutin to quercetin.

A Review on Epidemiological and Clinical Studies on Buckwheat Allergy

BACKGROUND

Cultivated buckwheat include two species originating from China: common buckwheat (Fagopyrum esculentum) and tartary buckwheat (Fagopyrum tartaricum). Buckwheat can cause IgE-mediated allergy, including severe allergic reactions and anaphylaxis. Exposure can occure when eating buckwheat food (food allergen), when producing or handling buckwheat food (occupational exposure) or when sleeping on buckwheat husk pillows (houeshold environmental exposure).

METHODS

A search on buckwheat allergy in the medical datbase PubMed from 1970-2020.

RESULT

A number of allergenic proteins have been identified in common buckwheat (e.g., Fag e 1, Fag e 2 and Fag e 3) and in tartary buckwheat (e.g., Fag t 1, Fag t 2, Fag t 3). Clinically relevant cross-reactivity has been described between buckwheat and peanut, latex, coconut, quinoa, and poppy seed. The prevalence of buckwheat allergy in the population can be estimated as 0.1-0.4% in Japan, Korea and buckwheat consuming areas of China. Among patients in allergy clinics in different countries, 2-7% has confirmed buckwheat allergy. School studies from Japan and Korea found 4-60 cases of buckwheat-related anaphylaxis per 100,000 school children. The incidence of severe allergic reactions to buckwheat, including anaphylaxis, can be estimated as 0.1-0.01 cases per 100,000 person-years.

CONCLUSIONS

Buckwheat allergy is a neglected allegy deserving further attention but severe allergic reactions are rare.

Breeding Buckwheat for Increased Levels and Improved Quality of Protein

Tartary buckwheat (Fagopyrum tataricum (L.) Gaertn.) and common buckwheat (Fagopyrum esculentum Moench) are important sources of proteins with balanced amino-acid compositions, and thus of high nutritional value. The polyphenols naturally present in Tartary buckwheat and common buckwheat lower the true digestibility of the proteins. Digestion-resistant peptides are a vehicle for fecal excretion of steroids, and in this way, for bile acid elimination and reduction of cholesterol concentrations in serum. Buckwheat proteins are more effective compared to soy proteins for the prevention of gallstone formation. Tartary and common buckwheat grain that contains appropriate amounts of selenium-containing amino acids can be produced as functional food products. The protein-rich by-products of buckwheat are a good source of bioactive substances that can suppress colon carcinogenesis by reducing cell proliferation. The grain embryo is a rich source of proteins, so breeding buckwheat with larger embryos is a possible strategy to increase protein levels in Tartary and common buckwheat grain. However, chemical analysis of the grain is the most relevant criterion for assessing grain protein levels and quality.

Buckwheat proteins: functionality, safety, bioactivity, and prospects as alternative plant-based proteins in the food industry

The need for protein in human nutrition is rapidly increasing because of the increasing world population and consumer preference for high-protein foods. Plant proteins are gaining attention as sustainable means of meeting the global protein need due to their lower carbon footprint. Nonetheless, the food industry has neglected or underutilized many plant proteins, including buckwheat protein. Buckwheat is a pseudocereal and its groats contain beneficial components such as proteins, dietary fiber, vitamins, and bioactive polyphenols. The protein quality of buckwheat seeds varies between the tartary and common buckwheat types; both are gluten-free and contain considerable amount of indispensable amino acids. This review provides a detailed discussion on the profile, amino acid composition, digestibility, allergenicity, functional properties, and bioactivity of buckwheat proteins. Prospects of processing buckwheat for improving protein digestibility and deactivating allergenic epitopes were also discussed. Based on the literature, buckwheat protein has a tremendous potential for utilization in structuring food products and developing peptide-based functional foods for disease prevention. Future research should develop new processing technologies for further improvement of the quality and functional properties of buckwheat protein in order to facilitate its utilization as an alternative plant-based protein toward meeting the global protein supply.

Structure and diversity of 13S globulin zero-repeat subunit, the trypsin-resistant storage protein of common buckwheat (Fagopyrum esculentum M.) seeds

The zero-repeat subunit of 13S globulin, which lacks tandem repeat inserts, is trypsin-resistant and suggested to show higher allergenicity than the other subunits in common buckwheat (Fagopyrum esculentum Moench). To evaluate allelic variations and find novel alleles, the diversity of the zero-repeat genes was examined for two Japanese elite cultivars and 15 Pakistani landraces. The results demonstrated that two new alleles GlbNA1 and GlbNC1, plus three additional new alleles GlbNA2, GlbNA3, and GlbND, were identified besides the already-known GlbNA, GlbNB, and GlbNC alleles. In the Pakistani landraces, GlbNA was the most dominant allele (0.60-0.88 of allele frequency) in all except one landrace, where GlbNB was the most dominant allele (0.50 of allele frequency). Similar to GlbNC, the alleles GlbNA2 and GlbNA3 had extra ~200 bp MITE-like sequences around the stop codon. Secondary structure predictions of a sense strand demonstrated that the extra ~200 bp sequences of GlbNC, GlbNA2, and GlbNA3 can form rigid hairpin structures with free energies of -78.95, -67.06, and -29.90 kcal/mol, respectively. These structures may affect proper transcription and/or translation. In the GlbNC homozygous line, no transcript of a zero-repeat gene was detected, suggesting the material would be useful for developing hypoallergenic buckwheat.

Efficient transient gene expression system using buckwheat hypocotyl protoplasts for large-scale experiments

Buckwheat (Fagopyrum esculentum) is cultivated worldwide and its flour is used in a variety of food products. Although functional analyses of genes in buckwheat are highly desired, reliable methods to do it have yet to be developed. In this study we established a simple and efficient transient gene expression system using buckwheat protoplasts isolated from young hypocotyls using 96-well plates as a high-throughput platform. The transformation efficiency was comparable with that of similar systems, such as Arabidopsis mesophyll protoplasts. Stable results were obtained in a typical example of the experiment to examine transcription factor activity. This system shows potential for the large-scale analysis of gene function using protoplast isolated from fewer and younger plants than the conventional system and may provide novel information for efficient buckwheat breeding.

Antioxidant and Rutin Content Analysis of Leaves of the Common Buckwheat (Fagopyrum esculentum Moench) Grown in the United Kingdom: A Case Study

The common buckwheat, Fagopyrum esculentum Moench (Polygonaceae) is a gluten-free pseudocereal that has been gaining in popularity in recent years as a low-calorie and nutrient-rich healthy food option. Buckwheat farming is common in Eastern European countries and the Far East, while in the UK and other Western European countries, the plant has limited medicinal or food applications. The vegetative parts, particularly the leaves and flowers, are among the best-known sources of the bioactive compound, rutin. Hence, functional foods originated from buckwheat leaves are common, although the scope of such applications is limited by phototoxicity associated with the fagopyrin composition. Here, the antioxidant and rutin composition of the leaves of the plant grown in the UK are assessed. The methanol extract of the leaves displayed a potent DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging effect along with reducing power. Quantitative High Performance Liquid Chromatography (HPLC)-based analysis showed the rutin content of the leaves as 3417 mg/100g (on dry weight (DW) basis). The identity of rutin was also confirmed by isolation and structural elucidation based on spectroscopic studies. From the chemical content analysis, including fagopyrin levels and the antioxidant assays, UK-grown buckwheat has potential as a commercial source of rutin or as a functional food.

Activity-guided isolation of phase II enzyme inducers from buckwheat flour methanolic extracts

BACKGROUND

Buckwheat is an important alternative crop and a raw material for functional food formulation. Phase II detoxification proteins/enzymes provide cytoprotective roles against oxidative stress and inflammation originating from various stressors. We aimed to identify and characterize potential phase II enzyme inducers from methanolic extracts of buckwheat flour, using an activity-guided fractionation based on the induction of quinone reductase (QR) (EC 1.6.5.2) in Hepa 1c1c7 cells.

RESULTS

We isolated the QR inducers N-trans-feruloyltyramine (I), syringic acid (II), quercetin (III) and myricetin (IV). The relative QR-inducing ability, as well as the concentration required to double QR specific activity (CD values, in parentheses), decreased in the order: quercetin (3.0 µmol L^-1 ) > N-trans-feruloyltyramine (24 µmol L^-1 ) > myricetin (58 µmol L^-1 ) > syringic acid (5.4 mmol L^-1 ). Quercetin and N-trans-feruloyltyramine exhibited the greatest extent of QR induction of an approximately four-fold maximum induction and these compounds also exhibited the greatest values for the ratio of IC₅₀ (i.e. level to reduce viability by 50%): CD values of 11 and > 8.3, respectively, among the four QR inducers isolated. Isobologram analyses for binary combinations of compounds I-IV revealed primarily antagonistic interactions for QR induction.

CONCLUSION

These findings add to our understanding of the nutraceutical potential of buckwheat as a chemoprophylactic dietary component. © 2018 Society of Chemical Industry.

Molecular allergen profiling in horses by microarray reveals Fag e 2 from buckwheat as a frequent sensitizer

Background

Companion animals are also affected by IgE‐mediated allergies, but the eliciting molecules are largely unknown. We aimed at refining an allergen microarray to explore sensitization in horses and compare it to the human IgE reactivity profiles.

Methods

Custom‐designed allergen microarray was produced on the basis of the ImmunoCAP ISAC technology containing 131 allergens. Sera from 51 horses derived from Europe or Japan were tested for specific IgE reactivity. The included horse patients were diagnosed for eczema due to insect bite hypersensitivity, chronic coughing, recurrent airway obstruction and urticaria or were clinically asymptomatic.

Results

Horses showed individual IgE‐binding patterns irrespective of their health status, indicating sensitization. In contrast to European and Japanese human sensitization patterns, frequently recognized allergens were Aln g 1 from alder and Cyn d 1 from Bermuda grass, likely due to specific respiratory exposure around paddocks and near the ground. The most prevalent allergen for 72.5% of the tested horses (37/51) was the 2S‐albumin Fag e 2 from buckwheat, which recently gained importance not only in human but also in horse diet.

Conclusion

In line with the One Health concept, covering human health, animal health and environmental health, allergen microarrays provide novel information on the allergen sensitization patterns of the companion animals around us, which may form a basis for allergen‐specific preventive and therapeutic concepts.

IgE-mediated food allergies in children: prevalence, triggers, and management

Food allergy (FA) is a serious health problem, and severe FA such as food-induced anaphylaxis can often be life threatening. The incidence of FA has been increasing especially in children. They usually develop early in life and affect up to 10% of children. The 2 most common food allergens worldwide are milk and eggs, while the third one varies depending on the countries: peanuts in the United States and Switzerland, wheat in Germany and Japan, tree nuts in Spain, sesame in Israel, and walnuts in Korea. These common food allergens are different and difficult to identify because of differing study methodologies, population, geography, age, and dietary exposure patterns. The current management of FA relies on the strict avoidance of culprit allergens, the prompt treatment of allergic reactions, including epinephrine use for food-induced anaphylaxis, monitoring, and education to prevent further reactions. Newer approaches for tolerance induction to FA and FA immunotherapy have been under investigation but are not yet ready for real-world application. Thus, consistent and systematic education of patients, caregivers, and food-handling people is of primary importance for the management and prevention of FA reactions. This review assesses and compares IgE-mediated FA in children in Korea and other countries, with a focus on summarizing the prevalence, common triggers, and management of FA.

Age-Based Causes and Clinical Characteristics of Immediate-Type Food Allergy in Korean Children

PURPOSE

Age-based causes and clinical characteristics of immediate-type food allergy (FA) have not been sufficiently studied. Therefore, we investigated age-dependent clinical profiles of FA in Korean children through an extensive multicenter investigation.

METHODS

Using a case report form developed by the authors, a retrospective medical record review was performed of patients (0-18 years old) diagnosed with immediate-type FA between September 2014 and August 2015 in 14 tertiary hospitals in Korea.

RESULTS

A total of 1,353 children and adolescents, 93% younger than 7 years, were enrolled in the present study, and 1,661 cases of immediate-type FA were recorded in these patients. The 7 major causative foods were cow's milk (28.1%), hen's eggs (27.6%), wheat (7.9%), walnuts (7.3%), peanuts (5.3%), buckwheat (1.9%), and shrimps (1.9%). Categorizing the patients into 4 age groups revealed that the most common causative food was different for each age group: cow's milk (<2 years), walnuts (2-6 years), walnuts (7-12 years), and buckwheat (13-18 years). The onset time of symptoms was less than 10 minutes in 49%, between 10 and 30 minutes in 17%, and between 30 minutes and 2 hours in 34% of cases. Food-induced anaphylaxis was reported in 506 (30.5%) out of 1,661 cases, and the 7 major causes of food-induced anaphylaxis was cow's milk (27.5%), hen's eggs (21.9%), wheat (11.3%), walnuts (10.5%), peanuts (5.9%), buckwheat (4.2%), and pine nuts (3.0%). The proportion of anaphylaxis was highest in the patients allergic to buckwheat (67.7%), followed by those allergic to pine nuts (57.7%), walnuts (43.8%), wheat (43.5%), and peanuts (34.1%).

CONCLUSIONS

The 5 major causative foods of immediate-type FA in Korean children were cow's milk, hen's eggs, wheat, walnuts, and peanuts. The distribution of causative foods was considerably distinctive according to different age groups. Anaphylaxis was reported in 30.5% of immediate-type FA cases.

Reactivity change of IgE to buckwheat protein treated with high-pressure and enzymatic hydrolysis

BACKGROUND

Buckwheat is a popular food material in eastern Asian countries that can cause allergenic response. This study was conducted to evaluate the effects of hydrolysis with papain and high-pressure (HP) treatment of buckwheat protein (BWP) on reactivity of immunoglobulin E (IgE) and its secondary structure.

RESULTS

Reactivity of IgE was examined by enzyme-linked immunosorbent assay (ELISA) with serum samples from 16 patients allergic to buckwheat. Reactivity of IgE to hydrolysate of BWP with papain showed a maximum decrease of 79.8%. After HP treatment at 600 MPa for 1 min, reactivity of IgE to BWP decreased by up to 55.1%. When extracted, BWP was hydrolyzed with papain overnight following HP treatment at 600 MPa which the reactivity of IgE decreased significantly by up to 87.1%. Significant changes in secondary structure of BWP were observed by circular dichroism (CD) analysis after hydrolysis with papain following HP treatment.

CONCLUSION

Reduction of reactivity of IgE showed a correlation with changes in secondary structure of BWP, which may cause changes in conformational epitopes. This suggests the possibility of decreasing the reactivity of IgE to BWP using combined physical and enzymatic treatments.

Chemical composition and health effects of Tartary buckwheat

Tartary buckwheat (Fagopyrum tataricum) contains a range of nutrients including bioactive carbohydrates and proteins, polyphenols, phytosterols, vitamins, carotenoids, and minerals. The unique composition of Tartary buckwheat contributes to their various health benefits such as anti-oxidative, anti-cancer, anti-hypertension, anti-diabetic, cholesterol-lowering, and cognition-improving. Compared with the more widely cultivated and utilised common buckwheat (F. esculentum), Tartary buckwheat tends to contain higher amounts of certain bioactive components such as rutin, therefore, showing higher efficiency in preventing/treating various disorders. This review summarises the current knowledge of the chemical composition of Tartary buckwheat, and their bio-functions as studied by both in vitro and in vivo models. Tartary buckwheat can be further developed as a sustainable crop for functional food production to improve human health.

Hypolipidemic activity of common (Fagopyrum esculentum Moench) and tartary (Fagopyrum tataricum Gaertn.) buckwheat

Buckwheat grain has well-balanced nutritional value, whereas its digestibility is relatively low. This review summarizes recent advances in studies on the hypolipidemic activity of buckwheat. The most remarkable function is a powerful hypocholesterolemic activity of buckwheat protein in rats, which is far stronger than that of soy protein. The cholesterol-lowering effect is mediated by mechanisms involving higher excretion of fecal sterols and lower digestibility of buckwheat protein. The insoluble fraction of buckwheat protein associates with cholesterol and reduces micelle cholesterol uptake in caco-2 cells. Furthermore, consumption of buckwheat protein suppresses cholesterol-induced gallstones and body fat in rodents. Buckwheat sprouts also have hypolipidemic activity in rats or type 2 diabetic mice. Tartary buckwheat bran extract reduced the serum level of total cholesterol and triglyceride in hyperlipidemic rats. The consumption of buckwheat seed reduced low-density lipoprotein cholesterol in the pastureland Mongolian population. Taken together, buckwheat may be beneficial for prevention of hyperlipidemia.

Attitudes and preferences of consumers toward food allergy labeling practices by diagnosis of food allergies

BACKGROUND/OBJECTIVES

The objective of this study was to investigate food allergens and prevalence rates of food allergies, followed by comparison of consumer attitudes and preferences regarding food allergy labeling by diagnosis of food allergies.

SUBJECTS/METHODS

A total of 543 individuals living in Seoul and Gyeonggi area participated in the survey from October 15 to 22 in 2013.

RESULTS

The results show that the prevalence of doctor-diagnosed food allergies was 17.5%, whereas 6.4% of respondents self-reported food allergies. The most common allergens of doctor-diagnosed and self-reported food allergy respondents were peaches (30.3%) and eggs (33.3%), respectively, followed by peanuts, cow's milk, and crab. Regarding consumer attitudes toward food labeling, checking food allergens as an item was only significantly different between allergic and non-allergic respondents among all five items (P < 0.001). All respondents reported that all six items (bold font, font color, box frame, warning statement, front label, and addition of potential allergens) were necessary for an improved food allergen labeling system. PLSR analysis determined that the doctor-diagnosed group and checking of food allergens were positively correlated, whereas the non-allergy group was more concerned with checking product brands.

CONCLUSIONS

An effective food labeling system is very important for health protection of allergic consumers. Additionally, government agencies must develop policies regarding prevalence of food allergies in Korea. Based on this information, the food industry and government agencies should provide clear and accurate food labeling practices for consumers.

Effects of enzymatic hydrolysis of buckwheat protein on antigenicity and allergenicity

BACKGROUND/OBJECTIVES

Due to its beneficial health effects, use of buckwheat has shown a continuous increase, and concerns regarding the allergic property of buckwheat have also increased. This study was conducted for evaluation of the hydrolytic effects of seven commercial proteases on buckwheat allergens and its allergenicity.

MATERIALS/METHODS

Extracted buckwheat protein was hydrolyzed by seven proteolytic enzymes at individual optimum temperature and pH for four hours. Analysis was then performed using SDS-PAGE, immunoblotting, and competitive inhibition ELISA (ciELISA) with rabbit antiserum to buckwheat protein, and direct ELISA with pooled serum of 21 buckwheat-sensitive patients.

RESULTS

Alkaline protease, classified as serine peptidase, was most effective in reducing allergenicity of buckwheat protein. It caused decomposition of the whole buckwheat protein, as shown on SDS-PAGE, and results of immunoblotting showed that the rabbit antiserum to buckwheat protein no longer recognized it as an antigen. Allergenicity showed a decrease of more than 50% when pooled serum of patients was used in ELISA. Two proteolytic enzymes from Aspergillus sp. could not hydrolyze buckwheat allergens effectively, and the allergenicity even appeared to increase.

CONCLUSIONS

Serine-type peptidases appeared to show a relatively effective reduction of buckwheat allergenicity. However, the antigenicity measured using rabbit antiserum did not correspond to the allergenicity measured using sera from human patients. Production of less allergenic buckwheat protein may be possible using enzymatic hydrolysis.

Allergenic potential and enzymatic resistance of buckwheat

Buckwheat is known as a health food but is one of the major food allergens triggering potentially fatal anaphylaxis in Asia, especially in Japan and Korea. This study was conducted to investigate the characteristic of enzymatic resistance of buckwheat protein and allergenic potential. Enzymatic resistance of buckwheat protein was performed with in vitro digestibility test in simulated gastric fluid (SGF), pH 1.2, using pepsin and simulated intestinal fluid (SIF) using chymotrypsin. Reactivity of buckwheat proteins to human IgE was performed using six allergic patients sensitized to buckwheat. Buckwheat's IgE levels were measured using the Phadia UniCAP-system. Buckwheat protein, 16 kDa, still remained after 30 min treatment of pepsin on SDS-PAGE. Even though 16 kDa almost disappeared after 60 min treatment, two out of the six buckwheat patients' sera showed reactivity to hydrolysate after 60 min treatment, indicating that allergenicity still remained. In simulated intestinal fluid (SIF) using chymotrypsin, buckwheat protein, 24 kDa, showed resistance to hydrolysis with chymotrypsin on SDS-PAGE, and still had allergenicity based on the result of ELISA. Our results suggest that buckwheat proteins have strong resistance to enzyme degradation. This may be attributed in part to the allergenic potential of buckwheat. Further study should be continued regarding buckwheat allergy.

IgE mediated food allergy in Korean children: focused on plant food allergy

Food allergy (FA) is a worldwide problem, with increasing prevalence in many countries, and it poses a clearly increasing health problem in Korea. In Korea, as a part of International Study of Asthma and Allergy in Childhood (ISAAC), a series of nation-wide population studies for prevalence of allergic disease in children were carried out, with the Korean version of ISAAC in 1995, 2000, and 2010. From the survey, the twelve-month prevalence of FA showed no significant differences from 1995 to 2000 in both age groups (6-12 years-old, 6.5% in 1995 and 5.7% in 2000; 12-15 year-olds, 7.4% in 1995 and 8.6% in 2000). The mean lifetime prevalence of FA which had ever been diagnosed by medical doctor was 4.7% in 6-12 year-olds and 5.1% in 12-15 year-olds respectively in 2000. In Korean children, the major causes of FA are almost same as in other countries, although the order prevalence may vary, a prime example of which being that peanut and tree nut allergies are not prevalent, as in western countries. Both pediatric emergency department (ED) visits and deaths relating to food induced anaphylaxis have also increased in western countries. From a study which based on data from the Korean Health Insurance Review and Assessment Service (KHIRA) from 2001 to 2007, the incidence of anaphylaxis under the age of 19 was 0.7-1 per 100,000 person-year, and foods (24.9%) were the most commonly identified cause of childhood anaphylaxis. In another epidemiologic study, involving 78889 patients aged 0-18 years who visited the EDs of 9 hospitals during June 2008 to Mar 2009, the incidence of food related anaphylaxis was 4.56 per 10,000 pediatric ED visits. From these studies, common causes of food related anaphylaxis were seafood, buckwheat, cow's milk, fruits, peanut and tree nuts. Although systematic epidemiologic studies have not reported on the matter, recently, plant foods related allergy has increased in Korean children. Among 804 children with moderate to severe atopic dermatitis, we reveals that the peanut sensitization rate in Korea reaches 18%, and that, when sensitized to peanut, patients showed a significant tendency to have co-sensitization with house dust mites, egg white, wheat, and soybean. The higher specific IgE to peanut was related to the likelihood of the patient developing severe systemic reactions. In another study, based on the data analysis of 69 patients under 4 years of age who had suspected peanut and tree nut allergy, 22 (31.9%) were sensitized to walnut (>0.35 kU/L, 0.45-27.4 kU/L) and 6 (8.7%) experienced anaphylaxis due to a small amount of walnut exposure. Furthermore, in this review, clinical and immunological studies on plant food allergies, such as buckwheat allergy, rice allergy, barley allergy, and kiwi fruit allergy, in Korean children are discussed.

An autoclave treatment reduces the solubility and antigenicity of an allergenic protein found in buckwheat flour

The effects of an autoclave treatment of buckwheat flour on a 24-kDa allergenic protein were investigated by measuring reduction in solubility and antibody binding. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis showed that the intensity of the major bands, including that of the 24-kDa allergen, was reduced by the autoclave treatment. The protein solubility in buckwheat flour was variably decreased by the autoclave treatment. Enzyme-linked immunosorbent assay analysis using a monoclonal antibody specific for buckwheat 24-kDa protein showed that the reactivity of protein extracts (10 μg/ml) from buckwheat flour was lowered by the autoclave treatment. The autoclave treatment may reduce the major allergen content of buckwheat. Future studies will determine if autoclaving treatments affect the allergenicity of the 24-kDa buckwheat protein.

Food allergy

Food allergy is an important public health problem affecting 5% of infants and children in Korea. Food allergy is defined as an immune response triggered by food proteins. Food allergy is highly associated with atopic dermatitis and is one of the most common triggers of potentially fatal anaphylaxis in the community. Sensitization to food allergens can occur in the gastrointestinal tract (class 1 food allergy) or as a consequence of cross reactivity to structurally homologous inhalant allergens (class 2 food allergy). Allergenicity of food is largely determined by structural aspects, including cross-reactivity and reduced or enhanced allergenicity with cooking that convey allergenic characteristics to food. Management of food allergy currently focuses on dietary avoidance of the offending foods, prompt recognition and treatment of allergic reactions, and nutritional support. This review includes definitions and examines the prevalence and management of food allergies and the characteristics of food allergens.

Buckwheat allergy: a potential problem in 21st century Britain

Buckwheat is commonly consumed in many parts of the world and has recently become more available in the UK. Buckwheat allergy is well recognised in parts of mainland Europe and Asia, typically associated with consumption of specific regional foods. No adult cases of buckwheat allergy in the UK have been reported in the literature. The authors present two cases of buckwheat allergy that presented to our UK allergy service recently. A 57-year-old man presented with anaphylaxis after eating home-baked bread prepared using buckwheat flour bought in France. In the second case, a 63-year-old lady presented with bronchospasm and urticaria after consuming health-food muesli. Sensitisation was confirmed in both cases by positive skin prick testing and specific IgE to buckwheat. Given the growing popularity of foods that may contain buckwheat, including ethnic and health-food ranges, buckwheat allergy is likely to become increasingly common in the UK.

Epitope mapping and identification on a 3D model built for the tartary buckwheat allergic protein TBb

Allergic protein TBb, a major allergen in tartary buckwheat, was divided into four epitope-containing fragments and was named F1, F2, F3, and F4, respectively. Results of immunological assays revealed that F2 had the strongest IgE-binding activity to patient's sera, which indicated that it might contain the linear IgE-binding epitope of TBb. According to the results of sequence analysis and molecular modeling of tartary buckwheat allergen, three mutants of F2 gene (R139A, R141A, and D144A) were reconstructed using site-directed mutagenesis, and each mutant was expressed in Escherichia coli BL21 (DE3). Following purification by Ni(2+) affinity chromatography, enzyme-linked immunosorbent assay and dot blot were performed for wild-type F2 and its mutants using sera from buckwheat-allergic patients and a negative control (non-allergic patient). Results showed that mutants R139A and D144A had weaker IgE-binding activity to patient's sera than wild-type F2, implying that Arg(139) and Asp(144) might be involved in the allergic activity of TBb. However, R141A had the weakest IgE-binding activity, suggesting that Arg(141) may be the critical amino acid of TBb. This is the first report on the epitope mapping and identification of TBb. Our findings will contribute to the production of TBb hypoallergens and to allergen-specific immunotherapy for tartary buckwheat allergy.

Clinical manifestations, co-sensitizations, and immunoblotting profiles of buckwheat-allergic patients

BACKGROUND

  Buckwheat allergy is a rare food allergy in Europe and North America, whereas it is often described and studied in Asia. The aim of this study was to describe a series of patients with proven buckwheat allergy evaluated in an Italian allergy clinic. Co-sensitization to other food and inhalant allergens and immunoblotting profiles of buckwheat-allergic patients were studied.

METHODS

  Patients with suspected buckwheat allergy who attended the allergy clinic between January 1, 2006, and September 30, 2008, were evaluated. All patients underwent skin prick tests for a standard panel of inhalant and food allergens, prick-by-prick with buckwheat flour, buckwheat-specific IgE determinations, and double-blind placebo-controlled food challenge (DBPCFC) with buckwheat flour. Immunoblotting with buckwheat flour extract was performed on sera from buckwheat-allergic patients.

RESULTS

  Among 72 patients with suspected buckwheat allergy, 30 (41.7%) were sensitized to buckwheat and 24 had a positive DBPCFC. The mean buckwheat IgE level was 6.23 kUA/l (range, 0.16 to >100 kUA/l). Several IgE-binding proteins were identified and grouped into three patterns: a 16-kDa band in patients with predominantly gastrointestinal symptoms with grass and wheat flour co-sensitization, a 25-kDa band in patients with predominantly cutaneous symptoms and a low frequency of co-sensitization, and a 40-kDa band in patients with anaphylaxis and a low frequency of co-sensitization.

CONCLUSIONS

  Buckwheat allergy is an emerging food allergy in Italy. We identified three distinct patterns of clinical and laboratory characteristics, suggesting that specific allergens could be more frequently associated with clinical manifestations of different severity.

Molecular cloning, recombinant expression, and immunological characterization of a novel allergen from tartary buckwheat

Buckwheat is generally regarded as a nutritionally rich food source. However, earlier studies prove that it also causes allergies to subjects. Allergenic proteins with a strong IgE-binding activity have been identified in common buckwheat (CB) and a 24 kDa allergen (rTBa) in tartary buckwheat (TB). The objective of this research was to clone and express a novel allergen in tartary buckwheat and to evaluate its structure and immunological activity. The 1773 bp full-length cDNA was amplified and cloned from the total RNA of TB by polymerase chain reaction (PCR) and rapid amplification of cDNA ends (RACE) methods. Its nucleotide sequence had high similarity with legume-like 13S storage protein mRNA in CB. The deduced amino acid sequence included a putative signal peptide and 18 fragments as its epitope sites. The predicted full-length TB allergen sequence was found to have two domains, and the recombinant protein reacted with sera from patients with positive IgE binding to buckwheat and had a lower binding ability than the recombinant TBa and recombinant TBb (C- and N-terminal amino acid sequence of TBt codes for protein). This fact suggests that full-length TB allergen may hydrolyze to two domains in vivo, decreasing the IgE-binding ability.

A novel PCR method for quantification of buckwheat by using a unique internal standard material

A novel quantitative and specific method for detection of buckwheat, a known food allergen, in diverse food materials was developed by using a unique internal standard to compensate for the variability in DNA extraction and amplification efficiencies. The method was based on a real-time PCR targeting the internal transcribed spacer region of Fagopyrum spp. and was designed to detect both cultivated and wild buckwheat, because wild buckwheat might be potentially allergenic. As the internal standard material, ground seeds of statice (Limonium sinuatum) were added to food samples prior to DNA extraction, and the amount of statice DNA measured by real-time PCR was used to standardize the buckwheat content. Statice, an ornamental plant, was chosen as the internal standard material because it was readily available and was inferred to be least likely to be commingled in foods. The specificity of the PCR system was tested against commonly used food materials of plant origin. Quantitative results expressed in buckwheat protein concentrations (mean +/- standard deviation) for various food samples prepared to contain 10 ppm (wt/wt) of buckwheat flour (corresponding to 1.2-microg/g [ppm] buckwheat protein) ranged from 0.7 +/- 0.2 (rice) to 0.9 +/- 0.4 (wheat) and for 100-ppm (wt/wt) samples (12-microg/g [ppm] buckwheat protein) from 7.7 +/- 1.0 (pepper) to 9.8 +/- 0.5 (wheat) microg/g (ppm). The method's accuracy, sensitivity, and specificity were considered sufficient for detection of buckwheat contamination at the level required for compliance with the Japanese Food Allergen Labeling Regulation.

PCR method for detecting trace amounts of buckwheat (Fagopyrum spp.) in food

Buckwheat often causes severe allergic reactions, even when its ingestion level is extremely low. Therefore, buckwheat is listed in several countries as a common food allergen. In addition to common buckwheat and Tartarian buckwheat that are cultivated and consumed widely, wild buckwheat may be potentially allergenic. Food containing undeclared buckwheat poses a risk to patients with the buckwheat allergy. We describe in this report a PCR method to detect buckwheat DNA by using primers corresponding to the internal transcribed spacer region and the 5.8S rRNA gene. The method is buckwheat-specific and compatible with both cultivated and wild buckwheat of the Fagopyrum spp. Its sensitivity was sufficient to detect 1 ppm (w/w) of buckwheat DNA spiked in wheat DNA. This method should benefit food manufacturers, clinical doctors, and allergic patients by providing information on the presence of buckwheat contamination in food.

Buckwheat (Fagopyrum esculentum Moench) low molecular weight seed proteins are restricted to the embryo and are not detectable in the endosperm

Buckwheat (Fagopyrum esculentum Moench) proteins are nutritionally important because of their high and balanced content of essential amino acids making their biological value much higher than that of cereal proteins. We analyzed extracts of buckwheat endosperm and embryo proteins by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). On electropherograms of endosperm proteins, six intense bands were detected. Two most intense bands were in the range of molecular weights (M.W.s) from 50 to 60 kDa. Protein of 57 kDa has been shown not to cross-react against antibodies raised against proteins of M.W. ranging between 23 and 25 kDa. There are no reports about the allergenicity of other endosperm proteins. On the electropherogram of buckwheat endosperm no low M.W. proteins could be detected. In this study we have demonstrated the tissue specific presence of proteins of different size classes of the endosperm and embryo tissues.

[Anaphylactic shock due to French galette. Type I allergic reaction to buckwheat]

A 37-year-old woman twice developed a life-threatening anaphylactic reaction after eating galettes, a special French pancake from Brittany. She had tolerated ordinary pancakes and crepes for many years. The allergological work-up revealed a Type I allergic reaction to buckwheat contained in the galettes. A prick test to buckwheat was positive and specific IgE antibodies to buckwheat were found in her serum. In contrast to wheat, buckwheat is not a cereal but a gluten-free knot-grass, initially from Asia. Whenever a patient suffers from allergic reactions due to pastries, a buckwheat allergy should be considered.

Buckwheat pillow-induced asthma and allergic rhinitis

BACKGROUND

Immunoglobulin (Ig)E-mediated hypersensitivity is a mechanism suggested to explain adverse reactions to buckwheat. This is the first reported case in the United States of a person who developed asthma and worsening allergic rhinitis after exposure to a buckwheat pillow.

OBJECTIVE

To describe a patient who developed asthma and worsening allergic rhinitis after exposure to a buckwheat pillow and to provide evidence that the adverse reaction was IgE-mediated.

METHODS

The patient underwent skin prick and ImmunoCAP testing (Pharmacia Diagnostics, Kalamazoo, MI) to buckwheat as well as skin prick testing to several environmental allergens.

RESULTS

The patient showed a 4+ skin prick test response to buckwheat. He also showed 4+ positive skin prick responses to multiple trees, grasses, and weeds, Alternaria, Helminthosporium, dog, and histamine control and was 3+ positive to house-dust mites, Penicillium, Aspergillus, cat, and feather mix. His negative control was negative. His ImmunoCAP test for buckwheat-specific IgE was class 4, or strongly positive. He had normal spirometry values. Performance of house-dust mite avoidance measures did not result in improvement of the patient's symptoms. Removal of the patient's two buckwheat pillows resulted in resolution of his asthma and improvement of rhinitis symptoms.

CONCLUSIONS

The positive skin prick and ImmunoCAP test to buckwheat along with the positive clinical response to buckwheat pillow elimination support an IgE-mediated mechanism in explaining our patient's buckwheat pillow-induced asthma and allergic rhinitis.

The kiss of death: a severe allergic reaction to a shellfish induced by a good-night kiss

True (IgE-mediated) allergic reactions to crustaceans are relatively common and can be serious. A young woman with a clinical history of multiple urticarial reactions after touching shrimp and lobster dishes was seen in an emergency department of a Mayo Clinic-affiliated hospital for an anaphylactic reaction that developed immediately after she kissed her boyfriend. The boyfriend had eaten several shrimp just before the kiss. It is important to warn susceptible patients that food does not actually have to be eaten to trigger an allergic reaction; touching the offending food and kissing or touching someone who has recently eaten the food can be enough to cause a major reaction.