Allergy to Peanut, Soybean, and Other Legumes: Recent Advances in Allergen Characterization, Stability to Processing and IgE Cross-Reactivity

Identification and semi-quantification of protein allergens in complex mixtures using proteomic and AllerCatPro 2.0 bioinformatic analyses: a proof-of-concept investigation

The demand for botanicals and natural substances in consumer products has increased in recent years. These substances usually contain proteins and these, in turn, can pose a risk for immunoglobulin E (IgE)-mediated sensitization and allergy. However, no method has yet been accepted or validated for assessment of potential allergenic hazards in such materials. In the studies here, a dual proteomic-bioinformatic approach is proposed to evaluate holistically allergenic hazards in complex mixtures of plants, insects, or animal proteins. Twelve commercial preparations of source materials (plant products, dust mite extract, and preparations of animal dander) known to contain allergenic proteins were analyzed by label-free proteomic analyses to identify and semi-quantify proteins. These were then evaluated by bioinformatics using AllerCatPro 2.0 (https://allercatpro.bii.a-star.edu.sg/) to predict no, weak, or strong evidence for allergenicity and similarity to source-specific allergens. In total, 4,586 protein sequences were identified in the 12 source materials combined. Of these, 1,665 sequences were predicted with weak or strong evidence for allergenic potential. This first-tier approach provided top-level information about the occurrence and abundance of proteins and potential allergens. With regards to source-specific allergens, 129 allergens were identified. The sum of the relative abundance of these allergens ranged from 0.8% (lamb's quarters) to 63% (olive pollen). It is proposed here that this dual proteomic-bioinformatic approach has the potential to provide detailed information on the presence and relative abundance of allergens, and can play an important role in identifying potential allergenic hazards in complex protein mixtures for the purposes of safety assessments.

Recent advance in sesame allergens: Influence of food processing and their detection methods

Sesame (Sesamum indicum L.) is a valuable oilseed crop with numerous nutritional benefits containing a diverse range of bioactive compounds. However, sesame is also considered an allergenic food that triggers various mild to severe adverse reactions (e.g., anaphylaxis). Strict dietary avoidance of sesame components is the best option to protect the sensitized consumers. Sesame or sesame-derived foods are always consumed after certain food processing operations, which would cause a considerable impact on the structure of sesame proteins, changing their sensitization capacity and detectability. In the review, the molecular structure properties, and immunological characteristics of the sesame allergens were described. Meanwhile, the influence of food processing techniques on sesame proteins and the relevant detection techniques used for the sesame allergens quantification are also emphasized critically. Hopefully, this review could provide valuable insight into the development and management for the new "Big Eight" sesame allergen in food industry.

Development of validated sandwich ELISA for detecting peanut allergen Ara h 3 in food

Peanut is an important food that can cause food allergies, often leading to moderate and severe allergic symptoms such as skin rashes, asthma, and even anaphylactic shock.Research indicates that Ara h 3 is one of the major peanut allergen. In order to establish a simple analytical method for detecting Ara h 3, we developed a sandwich enzyme-linked immunosorbent assay (ELISA) with antibodies that were induced from purified Ara h 3. The experimental results showed that the purified Ara h 3 had good purity, and we successfully prepared capture and detection antibodies. The method established in this study exhibited high specificity and did not cross-react with soybeans, cashew nuts, and sesame. For validation, including precision, recovery and sensitivity were in good condition. We also detected the Ara h 3 in peanut related foods. Overall, the ELISA developed in this study is a reliable method for Ara h 3 detection.

Application of legumes in plant-based milk alternatives: a review of limitations and solutions

In recent years, a global shift has been observed toward reducing the consumption of animal-derived foods in favor of healthier and more sustainable dietary choices. This has led to a steady growth in the market for plant-based milk alternatives (PBMAs). Projections suggest that this market will reach a value of USD 69.8 billion by 2030. Legumes, being traditional and nutritious ingredients for PMBAs, are rich in proteins, dietary fibers, and other nutrients, with potential health benefits such as anticancer and cardiovascular disease prevention. In this review, the application of 12 legumes in plant-based milk alternatives was thoroughly discussed for the first time. However, compared to milk, processing of legume-based beverages can lead to deficiencies such as nutritional imbalance, off-flavor, and emulsion stratification. Considering the potential and challenges associated with legume-based beverages, this review aims to provide a scientific comparison between legume-based beverages and cow's milk in terms of nutritional quality, organoleptic attributes and stability, and to summarize ways to improve the deficiencies of legume-based beverages in terms of raw materials and processing method improvements. In conclusion, the legume-based beverage industry will be better enhanced and developed by improving the issues.

Discovery and characterization of dietary antigens in oral tolerance

Food antigens elicit immune tolerance through the action of regulatory T cells (Tregs) in the intestine. Although antigens that trigger common food allergies are known, the epitopes that mediate tolerance to most foods have not been described. Here, we identified murine T cell receptors specific for maize, wheat, and soy, and used expression cloning to de-orphan their cognate epitopes. All of the epitopes derive from seed storage proteins that are resistant to degradation and abundant in the edible portion of the plant. Multiple unrelated T cell clones were specific for an epitope at the C-terminus of 19 kDa alpha-zein, a protein from maize kernel. An MHC tetramer loaded with this antigen revealed that zein-specific T cells are predominantly Tregs localized to the intestine. These cells, which develop concurrently with weaning, constitute up to 2% of the peripheral Treg pool. Bulk and single-cell RNA sequencing revealed that these cells express higher levels of immunosuppressive markers and chemokines compared to other Tregs. These data suggest that immune tolerance to plant-derived foods is focused on a specific class of antigens with common features, and they reveal the functional properties of naturally occurring food-specific Tregs.

Localization of G1A1a Allergenic Domain Destroyed by Thermal Processing

Glycinin is an important allergenic protein. A1a is the acidic chain of the G1 subunit in glycinin (G1A1a), and it has strong allergenicity. In this study, we used phage display technology to express the protein of G1A1a and its overlapping fragments and an indirect enzyme-linked immunosorbent assay (iELISA) to determine the antigenicity and allergenicity of the expressed protein. After three rounds of screening, it was determined that fragment A1a-2-B-I (151SLENQLDQMPRRFYLAGNQEQEFLKYQQEQG181) is the allergenic domain of G1A1a destroyed by thermal processing. In addition, three overlapping peptides were synthesized from fragments A1a-2-B-I, and a linear epitope was found in this domain through methods including dot blot and iELISA. Peptide 2 (157DQMPRRFYLANGNQE170) showed allergenicity, and after replacing it with alanine, it was found that amino acids D157, Q158, M159, and Y164 were the key amino acids that affected its antigenicity, while Q158, M159, R162, and N168 affected allergenicity.

Structural, extraction and safety aspects of novel alternative proteins from different sources

With rapid population growth and continued environmental degradation, it is no longer sustainable to rely on conventional proteins to meet human requirements. This has prompted the search for novel alternative protein sources of greater sustainability. Currently, proteins of non-conventional origin have been developed, with such alternative protein sources including plants, insects, algae, and even bacteria and fungi. Most of these protein sources have a high protein content, along with a balanced amino acid composition, and are regarded as healthy and nutritious sources of protein. While these novel alternative proteins have excellent nutritional, research on their structure are still at a preliminary stage, particularly so for insects, algae, bacteria, and fungi. Therefore, this review provides a comprehensive overview of promising novel alternative proteins developed in recent years with a focus on their nutrition, sustainability, classification, and structure. In addition, methods of extraction and potential safety factors for these proteins are summarized.

Influence of Roasting Temperature on the Detectability of Potentially Allergenic Lupin by SDS-PAGE, ELISAs, LC-MS/MS, and Real-Time PCR

Seeds of "sweet lupins" have been playing an increasing role in the food industry. Lupin proteins may be used for producing a variety of foods, including pasta, bread, cookies, dairy products, and coffee substitutes. In a small percentage of the population, lupin consumption may elicit allergic reactions, either due to primary sensitization to lupin or due to cross-allergy with other legumes. Thus, lupin has to be declared on commercial food products according to EU food regulations. In this study, we investigated the influence of roasting seeds of the L. angustifolius cultivar "Boregine" on the detectability of lupin by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), ELISAs, LC-MS/MS, and real-time PCR. Seeds were roasted by fluidized bed roasting, and samples were drawn at seed surface temperatures ranging from 98 °C to 242 °C. With increasing roasting temperature, the extractability of proteins and DNA decreased. In addition, roasting resulted in lower detectability of lupin proteins by ELISAs and LC-MS/MS and lower detectability of DNA by real-time PCR. Our results suggest reduced allergenicity of roasted lupin seeds used for the production of "lupin coffee"; however, this has to be confirmed in in vivo studies.

Insight of pH-shifting as an effective pretreatment to reduce the antigenicity of lectin from red kidney bean (Phaseolus vulgaris L.) combining with autoclaving treatments: The structure investigation

Combined effects of pH-shifting and an autoclaving cycle (121 °C, 15 min) on red kidney bean lectin (RKBL) were investigated using intrinsic and extrinsic fluorescence, UV, FTIR, DSC, SEC, dot-blot analysis and in vitro digestibility. Spectroscopic studies suggested that the protein refolding was stable after 3 h incubation with the hydrophobic exposure after pH-shifting, and hydrophobicity was significantly increased with the formation of more looser structure, which would influence the structural stability of known epitopes. In details, the increase of β-turn and reduction of random coil was related with the lower denaturation enthalpy, while the protein aggregation was also observed in acidic treated samples after autoclaving. Lower antigenicity and good digestibility suggested the exposure of enzyme cutting sites, and confirmed the effectivity of pH-shifting prior to the autoclaving. Then the results would be beneficial to the development of hypoallergenic kidney bean foods.

Electrochemical immunosensor for point-of-care detection of soybean Gly m TI allergen in foods

Soybean is a legume with high technological functionality, commonly used by the food industry as an ingredient in different products. However, soybean is an allergenic food whose undeclared presence in processed foods may represent a public health risk. In this work, it was developed an efficient electrochemical immunosensor, targeting the soybean trypsin inhibitor (Gly m TI) allergen using commercial anti-Gly m TI IgG, aiming at detecting/quantifying minute amounts of soybean in different food formulations. For this purpose, model mixtures of different foods (sausages, cooked-hams, biscuits) were prepared to contain known amounts of soybean protein isolate (100,000-0.1 mg kg-1) and submitted to specific thermal treatments (autoclaving, oven-cooking, baking). The electrochemical immunosensor allowed quantifying down to 0.1 mg kg-1 of soybean in the three food matrices, raw and processed (0.0012 mg of Gly m TI/kg of matrix). Accordingly, the immunosensor is suitable for detecting traces of soybean in raw, processed, and complex foods, thus protecting 99 % of soybean-allergic patients.

Food Allergens of Plant and Animal Origin: Classification, Characteristics, and Properties

Food allergy is an adverse immune response to specific foods that can be either IgE-mediated or non-IgE mediated. The causes of IgE-mediated food allergy are multifactorial and involve genetic, dietary, and environmental factors. The prevalence of food allergy has increased over the last few decades, especially in urbanized, industrialized, and Westernized countries, and the epithelial barrier hypothesis has been recently suggested as a possible explanation for this increase. Food allergens of plant and animal origin are classified into a few families and superfamilies that are widely distributed and conserved. While it is known that food allergens share common properties, such as stability to enzymes and solubility, they also exhibit differential properties, and exceptions to the common characteristics exist. In recent years, novel characteristics of food allergens have been proposed based on their immunological properties and their ability to act as adjuvants or enhancers of the immune system.This chapter provides an overview of the current knowledge of food allergy, covering their prevalence, classification of food allergens from plant and animal origins, and recent advancements in the characterization of the properties of these allergens.

Benefits of Soybean in the Era of Precision Medicine: A Review of Clinical Evidence

Soybean (Glycine max) is an important ingredient of cuisines worldwide. While there is a wealth of evidence that soybean could be a good source of macronutrients and phytochemicals with health-promoting effects, concerns regarding adverse effects have been raised. In this work, we reviewed the current clinical evidence focusing on the benefits and risks of soybean ingredients. In breast, prostate, colorectal, ovarian, and lung cancer, epidemiological studies showed an inverse association between soybean food intake and cancer risks. Soybean intake was inversely correlated with risks of type 2 diabetes mellitus (T2DM), and soy isoflavones ameliorated osteoporosis and hot flashes. Notably, soybean was one of the dietary protein sources that may reduce the risk of breast cancer and T2DM. However, soybean had adverse effects on certain types of drug treatment and caused allergies. In sum, this work provides useful considerations for planning clinical soybean research and selecting dietary protein sources for human health.

Prospects for developing allergen-depleted food crops

In addition to the challenge of meeting global demand for food production, there are increasing concerns about food safety and the need to protect consumer health from the negative effects of foodborne allergies. Certain bio-molecules (usually proteins) present in food can act as allergens that trigger unusual immunological reactions, with potentially life-threatening consequences. The relentless working lifestyles of the modern era often incorporate poor eating habits that include readymade prepackaged and processed foods, which contain additives such as peanuts, tree nuts, wheat, and soy-based products, rather than traditional home cooking. Of the predominant allergenic foods (soybean, wheat, fish, peanut, shellfish, tree nuts, eggs, and milk), peanuts (Arachis hypogaea) are the best characterized source of allergens, followed by tree nuts (Juglans regia, Prunus amygdalus, Corylus avellana, Carya illinoinensis, Anacardium occidentale, Pistacia vera, Bertholletia excels), wheat (Triticum aestivum), soybeans (Glycine max), and kidney beans (Phaseolus vulgaris). The prevalence of food allergies has risen significantly in recent years including chance of accidental exposure to such foods. In contrast, the standards of detection, diagnosis, and cure have not kept pace and unfortunately are often suboptimal. In this review, we mainly focus on the prevalence of allergies associated with peanut, tree nuts, wheat, soybean, and kidney bean, highlighting their physiological properties and functions as well as considering research directions for tailoring allergen gene expression. In particular, we discuss how recent advances in molecular breeding, genetic engineering, and genome editing can be used to develop potential low allergen food crops that protect consumer health.

Food allergy - New risks through vegan diet? Overview of new allergen sources and current data on the potential risk of anaphylaxis

A vegan diet is increasingly en vogue, i.e., a diet based on plants, in which animal products are completely avoided, often for health and environmental reasons. The menu is supplemented with pulses (e.g., soy, lentils, peas), nuts (e.g., cashew, macadamia, almond, pecan, para, walnut) and seeds (e.g., chia, flaxseed) or pseudo-grains (quinoa, buckwheat). Indeed, the product range is expanding to include vegan foods such as milk alternatives (e.g., oat, almond, soy drinks) and cheese or meat substitutes (e.g., soy-based). Food allergies are also on the rise, with an increasing prevalence worldwide. It is worthy of note that the main allergens of anaphylactic reactions to food in adults are predominantly of plant origin, mainly pulses and nuts - the very foods that form the main source of protein in the vegan diet. In this context, allergies to storage proteins (e.g., Gly m 5 and Gly m 6 from soya beans) can lead to severe anaphylactic reactions, while highly processed substitute products containing plant protein isolates (e.g., pea flour) in concentrated form continue to be of particular concern and may therefore be allergologically problematic. In this article, we aim to provide an overview of allergens and emerging allergen sources in vegan foods and highlight the anaphylaxis risk of the vegan diet.

Nahrungsmittelallergie - Neue Risiken durch vegane Ernährung? Überblick zu neuen Allergenquellen und aktuelle Daten zum Anaphylaxierisiko: Food allergy - New risks through vegan diet? Overview of new allergen sources and current data on the potential risk of anaphylaxis

Zunehmend mehr Menschen ernähren sich aus gesundheitlichen und Umweltaspekten ausschließlich von pflanzlichen Nahrungsmitteln (vegan). Dabei werden vielfach Hülsenfrüchte (wie Soja, Linsen, Erbsen), Schalenfrüchte (Cashew, Macadamia, Mandel, Pekan‐, Para‐ und Walnuss), Samen und Saaten (wie Chia, Leinsamen) oder (Pseudo‐)Getreide (wie Quinoa, Buchweizen) verzehrt. Vegane Milchalternativen sind Hafer‐, Mandel‐ und Sojadrinks, auch Käse‐ sowie Fleischersatzprodukte basieren oft auf einer Sojagrundlage. Gleichzeitig nimmt die Prävalenz von Nahrungsmittelallergien weltweit zu. Pflanzenallergene aus Hülsen‐ und Schalenfrüchten, die in der veganen Ernährung die Hauptproteinquelle ausmachen, zählen zu den häufigsten Auslösern von Nahrungsmittelallergien bei Erwachsenen. Dabei kommt es bei Allergien auf Speicherproteine (wie Gly m 5 und Gly m 6 aus der Sojabohne) zu teils schweren anaphylaktischen Reaktionen. Besonderes Augenmerk liegt weiter auf hochverarbeiteten Ersatzprodukten, die Pflanzenproteinisolate (zum Beispiel Erbsenmehl) in konzentrierter Form enthalten und damit allergologisch problematisch werden können. In diesem Artikel geben wir einen Überblick über wichtige Allergene und neue Allergenquellen in ausgesuchten veganen Nahrungsmitteln und betrachten die vegane Ernährung unter allergologischen Aspekten.

A comprehensive review on glycation and its potential application to reduce food allergenicity

Food allergens are a major concern for individuals who are susceptible to food allergies and may experience various health issues due to allergens in their food. Most allergenic foods are subjected to heat treatment before being consumed. However, thermal processing and prolonged storage can cause glycation reactions to occur in food. The glycation reaction is a common processing method requiring no special chemicals or equipment. It may affect the allergenicity of proteins by altering the structure of the epitope, revealing hidden epitopes, concealing linear epitopes, or creating new ones. Changes in food allergenicity following glycation processing depend on several factors, including the allergen's characteristics, processing parameters, and matrix, and are therefore hard to predict. This review examines how glycation reactions affect the allergenicity of different allergen groups in allergenic foods.

Pollen Sensitization Can Increase the Allergic Reaction to Non-Cross-Reactive Allergens in a Soy-Allergic Patient

During and after the pollen season, an increase in food-triggered allergic symptoms has been observed in pollen-food syndrome patients, possibly due to seasonal boosting of pollen-IgE levels. It has been suggested that consumption of birch-pollen-related foods plays a role in seasonal allergenic inflammation. However, whether this increased pollen sensitization during the pollen season can also affect the allergenicity of allergens that are non-cross-reactive with birch pollen remains in question. This study presents the case of a patient with soy allergy and pollinosis, who experiences worsening of gastrointestinal (GI) symptoms during the birch pollen season even though the eliciting food factor does not cross-react with birch pollen allergens and their homologs (e.g., Bet v 1 and Gly m 4). The results showed a notable increase in sIgE for Gly m 4 (3.3 fold) and Bet v 1 (2.6 fold) during the birch pollen season compared to outside the birch pollen season, while Gly m 5 and Gly m 6 showed only a slight increase (1.5 fold). The basophil activation test (BAT) showed that in this patient Gly m 5 and Gly m 6 are clinically relevant soy allergens, which correlates with the reported clinical symptoms to processed soy. Moreover, the BAT against raw soy shows an increase in basophil activation during the birch pollen season and a negative basophil activation result outside the birch pollen season. Thus, the worsening of GI symptoms could possibly be due to an increase in IgE receptors, an over-reactive immune system, and/or significant intestinal allergic inflammation. This case highlights the importance of including allergens that do not cross-react with birch pollen and using a functional assay such as the BAT to evaluate clinical relevance when assessing birch pollen seasonal influence on soy allergenicity.

Is pea our hidden allergen? An American pediatric case series

Plant-based diets, consisting of legumes, are becoming increasingly a diet trend, thus a focus for food manufacturers as a source of protein. Allergy to legumes, specifically to green pea and dun pea, have been emerging. There is currently no data on pea allergy in the United States. As such, and with the progressive increase in pea/pea proteins inclusion into foods, we present in this case series children with allergic reactions to foods containing green peas or pea-protein.

Peanut Allergenicity: An Insight into Its Mitigation Using Thermomechanical Processing

Peanuts are the seeds of a legume crop grown for nuts and oil production. Peanut allergy has gained significant attention as a public health issue due to its increasing prevalence, high rate of sensitization, severity of the corresponding allergic symptoms, cross-reactivity with other food allergens, and lifelong persistence. Given the importance of peanuts in several sectors, and taking into consideration the criticality of their high allergic potential, strategies aiming at mitigating their allergenicity are urgently needed. In this regard, most of the processing methods used to treat peanuts are categorized as either thermal or thermomechanical techniques. The purpose of this review is to provide the reader with an updated outlook of the peanut’s allergens, their mechanisms of action, the processing methods as applied to whole peanuts, as well as a critical insight on their impact on the allergenicity. The methods discussed include boiling, roasting/baking, microwaving, ultrasonication, frying, and high-pressure steaming/autoclaving. Their effectiveness in alleviating the allergenicity, and their capacity in preserving the structural integrity of the treated peanuts, were thoroughly explored. Research data on this matter may open further perspectives for future relevant investigation ultimately aiming at producing hypoallergenic peanuts.

Consumer Perception and Acceptability of Lupin-Derived Products: A Systematic Review

The addition of lupin into other foods can enhance their nutritional value and may be an acceptable approach to introducing lupin into the food supply, particularly as an ingredient. Lupin could be used in many food products (bakery products, pasta, beverages, meat products and dairy products) to improve their protein content and possible nutraceutical effects. The main aim of this study is to summarise the recent formulation trends with lupin as an ingredient of new food products based on consumer perception and acceptability. The present systematic literature review was conducted through the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. The eligibility criteria for the articles to be considered were: (a) the manufacturing of a food product with lupin as a formulation ingredient; (b) the food product developed was tested by a sensorial panel. A total of 33 studies filled the inclusion criteria and were incorporated into the qualitative synthesis. The sensory analysis of each product was notoriously different based on the jury evaluators and measurement scales used but revealed high acceptability rates for possible future consumers. The high protein and fibre contents of lupin were the most cited reason associated with the importance of nutrient-rich food products for consumers. More research on foods with high nutrition profiles and well-established sustainability parameters is crucial to promote healthier food environments.

Allergenicity of peanut allergens and its dependence on the structure

Food allergies are a global food safety problem. Peanut allergies are common due, in part, to their popular utilization in the food industry. Peanut allergy is typically an immunoglobulin E-mediated reaction, and peanuts contain 17 allergens belonging to different families in peanut. In this review, we first introduce the mechanisms and management of peanut allergy, followed by the basic structures of associated allergens. Subsequently, we summarize methods of epitope localization for peanut allergens. These methods can be instrumental in speeding up the discovery of allergenicity-dependent structures. Many attempts have been made to decrease the allergenicity of peanuts. The structures of hypoallergens, which are manufactured during processing, were analyzed to strengthen the desensitization process and allergen immunotherapy. The identification of conformational epitopes is the bottleneck in both peanut and food allergies. Further, the identification and modification of such epitopes will lead to improved strategies for managing and preventing peanut allergy. Combining traditional wet chemistry research with structure simulation studies will help in the epitopes' localization.

EAACI Molecular Allergology User's Guide 2.0

Since the discovery of immunoglobulin E (IgE) as a mediator of allergic diseases in 1967, our knowledge about the immunological mechanisms of IgE-mediated allergies has remarkably increased. In addition to understanding the immune response and clinical symptoms, allergy diagnosis and management depend strongly on the precise identification of the elicitors of the IgE-mediated allergic reaction. In the past four decades, innovations in bioscience and technology have facilitated the identification and production of well-defined, highly pure molecules for component-resolved diagnosis (CRD), allowing a personalized diagnosis and management of the allergic disease for individual patients. The first edition of the "EAACI Molecular Allergology User's Guide" (MAUG) in 2016 rapidly became a key reference for clinicians, scientists, and interested readers with a background in allergology, immunology, biology, and medicine. Nevertheless, the field of molecular allergology is moving fast, and after 6 years, a new EAACI Taskforce was established to provide an updated document. The Molecular Allergology User's Guide 2.0 summarizes state-of-the-art information on allergen molecules, their clinical relevance, and their application in diagnostic algorithms for clinical practice. It is designed for both, clinicians and scientists, guiding health care professionals through the overwhelming list of different allergen molecules available for testing. Further, it provides diagnostic algorithms on the clinical relevance of allergenic molecules and gives an overview of their biology, the basic mechanisms of test formats, and the application of tests to measure allergen exposure.

Changes in Serum Protein-Peptide Patterns in Atopic Children Allergic to Plant Storage Proteins

Next to cow's milk and eggs, plant foods, i.e., legumes, tree nuts and cereal grains, most often sensitise atopic children. Storage proteins constitutes the most relevant protein fraction of plant foods, causing primary sensitisation. They exhibit strong allergenic properties and immunogenicity. Our goal was to analyse sensitisation to 26 plant storage proteins in a group of 76 children aged 0-5 years with chronic symptoms of atopic dermatitis using Allergy Explorer ALEX2 and to discover changes in serum protein-peptide patterns in allergic patients with the use of MALDI-TOF-MS. We reported that 25% of children were allergic to 2S albumins, 19.7% to 7S globulins, 13.2% to 11S globulins and 1.3% to cereal prolamins. The most common allergenic molecules were Ara h 1 (18.4%), Ara h 2 (17.1%), Ara h 6 (15.8%) and Ara h 3 (11.8%) from peanuts, and the mean serum sIgE concentrations in allergic patients were 10.93 kUA/L, 15.353 kUA/L, 15.359 kUA/L and 9.038 kUA/L, respectively. In children allergic to storage proteins compared to the other patients (both allergic and non-allergic), the cell cycle control protein 50A, testis-expressed sequence 13B, DENN domain-containing protein 5A and SKI family transcriptional corepressor 2 were altered. Our results indicate that the IgE-mediated allergy to storage proteins is a huge problem in a group of young, atopic children, and show the potential of proteomic analysis in the prediction of primary sensitisation to plant foods. It is the next crucial step for understanding the molecular consequences of allergy to storage proteins.

Allergenic risk assessment of cowpea and its cross-reactivity with pea and peanut

BACKGROUND

Novel protein sources can represent a risk for allergic consumers. The aim of this study was to evaluate the allergenicity of cowpea (Vigna unguiculata), an increasingly consumed legume and potential new industrial food ingredient which may put legume-allergic patients at risk.

METHODS

Children with allergy to legumes associated to peanut (LP group: n = 13) or without peanut allergy (L group: n = 14) were recruited and sensitization to several legumes including cowpea was assessed by prick tests and detection of specific IgE (sIgE). Cowpea protein extract was analyzed by SDS-PAGE and immunoblotting, IgE-reactive spots were subjected to mass spectrometry. IgE-cross-reactivity between cowpea, pea, and peanut was determined using ELISA inhibition assays. Basophil activation tests were performed to evaluate sensitivity and reactivity of patient basophils toward legumes.

RESULTS

Prick tests and sIgE levels to cowpea were positive in 8/14 and 4/13 patients of the L group and in 9/13 and 10/13 patients of the LP group, respectively. Four major IgE-binding proteins were identified as vicilins and seed albumin. Cowpea extract and its vicilin fraction strongly inhibited IgE-binding to pea and peanut extract. Peanut, lentil, and pea were the strongest activators of basophils, followed by cowpea, soybean, mung bean, and lupin.

CONCLUSION

A majority of patients with legume allergy were sensitized to cowpea proteins. Four novel allergens were identified in cowpea, among which storage proteins were playing an important role in IgE-cross-reactivity, exposing legume-allergic patients to the risk of clinical cross-reactivity to cowpea and thus adding cowpea to the group of nonpriority legumes that are not subjected to allergen labeling such as chickpea, pea, and lentil.

Cottonseed Meal Protein Isolate as a New Source of Alternative Proteins: A Proteomics Perspective

Cottonseed meal (CSM) is a good source of dietary proteins but is unsuitable for human consumption due to its gossypol content. To unlock its potential, we developed a protein extraction process with a gossypol removal treatment to generate CSM protein isolate (CSMPI) with ultra-low gossypol content. This process successfully reduced the free and total gossypol content to 4.8 ppm and 147.2 ppm, respectively, far below the US FDA limit. In addition, the functional characterisation of CSMPI revealed a better oil absorption capacity and water solubility than pea protein isolate. Proteome profiling showed that the treatment improved protein identification, while SDS-PAGE analysis indicated that the treatment did not induce protein degradation. Amino acid analysis revealed that post-treated CSMPI was rich in branched-chain amino acids (BCAAs). Mass spectrometry analysis of various protein fractions obtained from an in vitro digestibility assay helped to establish the digestibility profile of CSM proteins. Several potential allergens in CSMPI were also found using allergenic prediction software, but further evaluation based on their digestibility profiles and literature reviews suggests that the likelihood of CSMPI allergenicity remains low. Overall, our results help to navigate and direct the application of CSMPIs as alternative proteins toward nutritive human food application.

Relevance of sensitization to legumes in peanut-allergic children

BACKGROUND

Legume consumption has increased during the two past decades. In France, legumes are responsible for 14.6% of food-related anaphylaxis in children, with peanut as the main allergen (77.5%). Few studies have demonstrated cross-reactivities between peanut and other legumes. The aim of this study was to determine prevalence and relevance of sensitization to legumes in peanut-allergic children.

METHODS

All children, aged of 1-17 years, admitted to the Pediatric Allergy Department of the University Hospital of Nancy between January 1, 2017 and February 29, 2020 with a confirmed peanut allergy (PA) and a documented consumption or sensitization to at least one other legume were included. Data were retrospectively collected regarding history of consumption, skin prick tests, specific immunoglobulin E (IgE), prior allergic reactions, and oral food challenges for each legume.

RESULTS

Among the 195 included children with PA, 122 were sensitized to at least one other legume (63.9%). Main sensitizations were for fenugreek (N = 61, 66.3%), lentil (N = 38, 42.2%), soy (N = 61, 39.9%), and lupine (N = 63, 34.2%). Among the 122 sensitized children, allergy to at least one legume was confirmed for 34 children (27.9%), including six children who had multiple legume allergies (4.9%). Lentil, lupine, and pea were the main responsible allergens. Half of allergic reactions to legumes other than peanut were severe.

CONCLUSION

The high prevalence of legume sensitization and the frequent severe reactions reported in children with PA highlight that tolerated legume consumption should be explored for each legume in the case of PA, and sensitization should be investigated if not.

Monitoring starch hydrolysis with micro visco-amylo-graph for the production of chickpea milk and optimization of the parameters with response surface methodology

Plant-based milk products are gaining attention since it has been demonstrated that the consumption of animal-derived foods had to be reduced to combat global climate change. The production of plant-based milk includes a starch hydrolysis step for raw materials with high starch content such as cereals and pulses, since the gelatinized starch forms a thick slurry which causes an unsuitable consistency for a drinkable product. The objectives of this work were to investigate the effects of slurry concentration (solid to solvent ratio), enzyme including temperature, enzyme amount and mixing (rotation) speed on the pasting properties especially final viscosity of a crude chickpea milk and also to investigate the potential use of Micro Visco Amylo-Graph for monitoring starch hydrolysis. Response surface methodology, based on Box Behnken Design, was used to assess the parameters and to optimize the hydrolysis conditions for the minimum final viscosity. In conclusion, it was observed that slurry concentration and enzyme including temperature were the most critical factors that affect either the pasting properties or the final viscosity of the crude chickpea milk. Briefly, lower final viscosities were obtained from samples which were prepared at lower beginning concentrations and treated with higher enzyme amounts at lower temperatures.

Sensitive and selective detection of peanut allergen Ara h 1 by ELISA and lateral flow immunoassay

The Ara h1 protein is a peanut allergen and it provides a useful biomarker for the detection of peanut protein. In this manuscript, we describe the generation of monoclonal antibodies (MAbs) against the Ara h1 protein and their development into sensitive and selective immunoassays for peanut detection. Our enzyme-linked immunosorbent assay (sELISA) detects a peanut meal standard with a sensitivity of 10 ng/mL and 500 ng/mL by lateral flow immunoassay (LFIA). MAb Ara h1 binding epitopes were identified, and immunoassay detection was limited to peanut meal varieties irrespective of thermal treatment. No binding was observed from tree nut meals (100-0.4 µg/mL). Peanut allergen detection during food manufacturing can limit the incidence of product recall resulting from cross-contact contamination or improper labeling of finished food products. Detection of Ara h1 by immunoassay can provide a cost-effective method for rapid surveillance of peanut during food production and prior to consumption.

Impact of Food Matrices on Digestibility of Allergens and Poorly Allergenic Homologs

Background

Protease resistance is considered a risk factor for allergenicity of proteins, although the correlation is low. It is nonetheless a part of the weight-of-evidence approach, proposed by Codex, for assessing the allergenicity risk of novel food proteins. Susceptibility of proteins to pepsin is commonly tested with purified protein in solution.

Objective

Food proteins are rarely consumed in purified form. Our aim was to evaluate the impact of experimental and endogenous food matrices on protease susceptibility of homologous protein pairs with different degrees of allergenicity.

Methods

Porcine and shrimp tropomyosin (ST) were subjected to sequential exposure to amylase, pepsin, and pancreatin in their respective endogenous matrix (pork tenderloin/boiled shrimp) and in three different experimental matrices (dessert mousse [DM], soy milk [SM], and chocolate bar [CB]). Digestion was monitored by immunoblotting using tropomyosin-specific antibodies. Recombinant peach and strawberry lipid transfer protein were biotinylated, spiked into both peach and strawberry fruit pulp, and subjected to the same sequential digestion protocol. Digestion was monitored by immunoblotting using streptavidin for detection.

Results

Chocolate bar, and to a lesser extent SM, had a clear protective effect against pepsin digestion of porcine tropomyosin (PT) and to a lesser extent of ST. Increased resistance was associated with increased protein content. Spiking experiments with bovine serum albumin (BSA) confirmed the protective effect of a protein-rich matrix. The two tropomyosins were both highly resistant to pepsin in their protein-rich and lean native food matrix. Pancreatin digestion remained rapid and complete, independent of the matrix. The fat-rich environment did not transfer protection against pepsin digestion. Spiking of recombinant peach and strawberry lipid transfer proteins into peach and strawberry pulp did not reveal any differential protective effect that could explain differences in allergenicity of both fruits.

Conclusions

Protein-rich food matrices delay pepsin digestion by saturating the protease. This effect is most apparent for proteins that are highly pepsin susceptible in solution. The inclusion of food matrices does not help in understanding why some proteins are strong primary sensitizers while homologs are very poor allergens. Although for induction of symptoms in food allergic patients (elicitation), a protein-rich food matrix that may contribute to increased risk, our results indicate that the inclusion of food matrices in the weight-of-evidence approach for estimating the potential risks of novel proteins to become allergens (sensitization), is most likely of very limited value.

Molecular and immunological characterization of cysteine protease from Phaseolus vulgaris and evolutionary cross-reactivity

A commonly consumed legume in India, the kidney bean (Phaseolus vulgaris) is associated with allergy. We report molecular and immunological characterization of cysteine protease allergen and its cross-reactivity. In silico allergenicity assessment and phylogenetic analysis of kidney bean cysteine protease showed significant sequence homology (upto 67%) with allergens from kiwi, papaya, soybean, ragweed pollen and mites. Physicochemical properties and motif-analysis depicted cysteine protease as probable allergen. Multiple sequence alignment and phylogenetic analysis indicated structural conservation between kidney bean and homologous cysteine protease sequences. The gene was cloned, expressed and affinity purified. Cysteine protease was resolved at 42 kDa and exhibited high IgE binding (up to 89%) with hypersensitive sera. Cysteine protease showed functional property on cross-linking IgE receptors and upregulated expression of CD203c on activated basophils. In inhibition studies, 8.4 ng of cysteine protease was required for 50% self-inhibition, whereas significant inhibition was also observed with kidney bean (52 ng), black gram (155 ng), chick pea (437 ng), mesquite pollen (36 ng), house dust mite (64.85 ng), Alternaria alternata (78.8 ng) and Curvularia lunata (73.6 ng) extracts. ConSurf analysis indicated conserved active site and catalytic residues in mature domain among proteases from legumes, fruits, pollens, mites and fungus. In summary, P. vulgaris cysteine protease was molecularly characterized having functional activity. This study demonstrated, cross-reactivity between food and aeroallergens based on evolutionary conservancy that showed its clinical importance as cross-reactive allergen. PRACTICAL APPLICATIONS: Adaptation of sustainable lifestyle has led to a surge in consumption of plant-based foods especially legumes. Their high nutritional content lowers the risk of developing cardiovascular diseases, diabetes, obesity, and stroke. Kidney beans, a commonly consumed legume in Indian subcontinent, have a potential to be used as nutraceutical and functional food. Despite its alimentary nature, it elicits allergic reactions. Being a major sensitizer, trivial information regarding its allergic components has led to an urgent need for exploring its allergen repertoire. Our study reported biochemical and immunological characterization of its major cysteine protease allergen. Cysteine proteases are major cross-reactive allergens from insects, fruits and fungal sources. Identification and molecular characterization of such immunodominant allergens by RDT offers the prospect of using recombinant proteins for accurate diagnosis and therapeutic purposes. This study suggests that a potential major cross-reactive allergen may aid in developing allergy management interventions for a wide range of allergenic sources.

Utility of the Basophil Activation Test Using Gly m 4, Gly m 5 and Gly m 6 Molecular Allergens for Characterizing Anaphylactic Reactions to Soy

There are two major clinically described forms of IgE-dependent soy allergy: (i) a primary dietary form, linked to sensitization against soy storage proteins Gly m 5 and Glym 6, and (ii) a form included in birch-soy syndromes linked to Gly m 4, a PR-10-like allergen. This second form sometimes causes severe systemic reactions, even anaphylaxis, especially on consuming certain forms of soy such as soymilks or smoothies. Skin prick tests and specific IgE assays against soy whole extracts lack sensitivity. Assays of anti-Gly m 4, Gly m 5 and Gly m 6 specific IgEs have been developed to overcome this obstacle, but they unfortunately lack specificity, especially for anti-Gly m 4. We hypothesized that the basophil activation test (BAT) using molecular soy allergens Gly m 4, Gly m 5 and Gly m 6 would both remedy the lack of sensitivity of other tests and offer, through its mechanistic contribution, greater specificity than the assay of anti-Gly m 4 specific IgEs. This would enable the two types of soy allergy to be separately identified. In a characteristic clinical example of PR-10-induced anaphylactic reaction after consuming soymilk, we report preliminary results of Gly m 4-exclusive positivity of BAT supporting our hypothesis. It will be necessary to confirm these results on more patients in subsequent studies, and to specify the place of the BAT in an overall diagnostic strategy. Meanwhile, soy BAT using molecular allergens is a promising diagnostic tool for soy allergy and probably also for follow-up in specific immunotherapies.

[Role of vegan diets in food allergies-risk of developing food anaphylaxis?]

We report about a 28-year-old woman with an anaphylactic reaction to falafel. The diagnosis of type 1 allergy to peas was made based on the detailed medical history, the sensitization profile and an oral food challenge. Pea (Pisum sativum) is a legume that is increasing used, for example, as protein flour in vegetarian and vegan food products. In addition to the case report, we discuss the anaphylaxis risk of food used in the vegan diet.

Peanut oral immunotherapy – current trends in clinical trials

Immunotherapy for allergy has been practised for over 100 years. Low-dose repeated exposure to specific allergen extracts over several months to years can successfully induce clinical tolerance in patients with allergy to insect venoms, pollen, house dust mite and domestic animals. Different regimens and routes for immunotherapy include subcutaneous, sublingual, oral and intralymphatic. Food allergies have been difficult to treat in this way due to high anaphylactic potential and only recently the first immunotherapy for peanut allergy has received regulatory approval. Several clinical trials have indicated high efficacy in desensitisation of peanut-allergic individuals using oral immunotherapy, which allows for safer administration of relatively high allergen concentrations. Still, the risk of adverse events including serious allergic reactions and high anxiety levels for patients remains, demonstrating the need for further optimisation of treatment protocols. Here we discuss the design and outcomes of recent clinical trials with traditional oral immunotherapy, and consider alternative protocols and formulations for safer and more effective oral treatment strategies for peanut allergy.

Selection of Specific Nanobodies against Lupine Allergen Lup an 1 for Immunoassay Development

The declaration of lupine supplements is mandatory to avoid lupine allergy for sensitive individuals. However, reliable detection methods against lupine allergen remain critical to prevent the unintended consumption of allergen contaminated food. In this study, we have immunized an alpaca with lupine protein extracts and retrieved nanobodies (Nbs). Nevertheless, the target antigen has been recognized as Lup an 1, which has been classified as β-conglutin, and confirmed to connect with lupine allergy. After selection of the best Nb-pair, a sandwich enzyme-linked immunosorbent assay (ELISA) has been developed providing a linear range of 0.036–4.4 μg/mL with detection limit of 1.15 ng/mL. This immunoassay was confirmed by detecting the samples with spiked allergen, and a recovery from 86.25% to 108.45% with coefficient of variation (CV) less than 4.0% has been determined. Generally, this study demonstrated the selection of Nbs against allergen with crude protein content to develop the immunoassay for lupine surveillance in foods.

Irradiation technology: An effective and promising strategy for eliminating food allergens

Food allergies are one of the major health concerns worldwide and have been increasing at an alarming rate in recent times. The elimination of food allergenicity has been an important issue in current research on food. Irradiation is a typical nonthermal treatment technology that can effectively reduce the allergenicity of food, showing great application prospects in improving the quality and safety of foods. In this review, the mechanism and remarkable features of irradiation in the elimination of food allergens are mainly introduced, and the research progress on reducing the allergenicity of animal foods (milk, egg, fish and shrimp) and plant foods (soybean, peanut, wheat and nuts) using irradiation is summarized. Furthermore, the influencing factors for irradiation in the elimination of food allergens are analyzed and further research directions of irradiation desensitization technology are also discussed. This article aims to provide a reference for promoting the application of irradiation technology in improving the safety of foods.

Protein profile of commercial soybean milks analyzed by label-free quantitative proteomics

The consumption of soy milk is increasing worldwide for its nutritional value and health benefits, however, its protein composition after commercialization is not well known. Technological and thermal treatments to which soy milk is subjected could affect the protein composition of the commercial products. This study compared the protein profile of 15 different commercial soy milks using a label-free quantitative proteomics approach. Proteins related to nutrient reservoir activity, endopeptidase inhibitor activity, lipid binding, and seed maturation contribute the most in terms of percentage mass. Their associated Gene Ontology terms are also enriched. Samples clustered into three groups based on their protein composition, with glycinins and beta-conglycinins being the most influential for determining the clustering. Amino acid composition estimated from the proteomics data also reflects the clustering of samples. Twenty allergenic proteins varying in abundance were identified, with Gly m 5 and Gly m 6 being the predominantly abundant allergens.

Identification of a vicilin-like major allergen from Prosopis juliflora exhibiting cross- reactivity with legume food allergens

BACKGROUND

Prosopis juliflora is a clinically relevant allergic sensitizer worldwide and shares cross-reactivity with allergens from several tree pollen and food. The present study aims to purify and immunobiochemically characterize a major allergen from Prosopis pollen. The allergen was further investigated for its cross-reactivity with legume allergens.

METHODS

Prosopis extract was fractionated by Q Sepharose and Superdex 75 gel filtration column to purify the allergen. Specific IgE against purified protein was estimated via ELISA and immunoblot. The protein was subjected to mass spectrometric analysis. Glycan characterization was performed by Schiff staining and lectin binding assay followed by deglycosylation studies. The functional activity of the purified protein was evaluated by the basophil activation test. Cross-reactivity was assessed by inhibition studies with legume extracts.

RESULTS

A 35 kDa protein was purified and showed 75% IgE reactivity with the patients' sera by ELISA and immunoblot. Glycan characterization of protein demonstrated the presence of terminal glucose and mannose residues. A reduction of 40% and 27% in IgE binding was observed upon chemical and enzymatic deglycosylation of the protein, respectively. The glycoprotein allergen upregulates the expression of CD203c on basophils which was significantly reduced upon deglycosylation, signifying its biological ability to activate the effector cells. The identified protein shared significant homology with Lup an 1 from the lupine bean. Immunoblot inhibition studies of the purified allergen with legume extracts underlined high cross-reactive potential. Complete inhibition was observed with peanut and common bean, while up to 70% inhibition was demonstrated with soy, black gram, chickpea, and lima bean.

CONCLUSION

A 35 kDa vicilin-like major allergen was isolated from P. juliflora. The protein possesses glycan moieties crucial for IgE binding and basophil activation. Furthermore, the purified protein shows homology with Lup an 1 and exhibits cross-reactivity with common edible legume proteins.

Tuning IgE: IgE-Associating Molecules and Their Effects on IgE-Dependent Mast Cell Reactions

The recent emergence of anti-immunoglobulin E (IgE) drugs and their candidates for humans has endorsed the significance of IgE-dependent pathways in allergic disorders. IgE is distributed locally in the tissues or systemically to confer a sensory mechanism in a domain of adaptive immunity to the otherwise innate type of effector cells, namely, mast cells and basophils. Bound on the high-affinity IgE receptor FcεRI, IgE enables fast memory responses against revisiting threats of venoms, parasites, and bacteria. However, the dysregulation of IgE-dependent reactions leads to potentially life-threatening allergic diseases, such as asthma and anaphylaxis. Therefore, reactivity of the IgE sensor is fine-tuned by various IgE-associating molecules. In this review, we discuss the mechanistic basis for how IgE-dependent mast cell activation is regulated by the IgE-associating molecules, including the newly developed therapeutic candidates.