Egg Allergy: Diagnosis and Immunotherapy

Screening, identification, and application of aptamers against allergens in food matrices

Food allergies have become one of the most pressing issues in food safety and public health globally along with their incidence increasing in recent years. The reliable recognition of allergens from different sources, especially food-hidden allergens, is essential for preventing and controlling food allergies. Recently, aptamers, as emerging recognition elements, have gained considerable attention in food allergy, especially in the detection of food allergens. This review systematically summarizes the latest progress in screening, identification, and application of aptamers against food allergens over the past five years. We first introduce a brief overview of food allergy and aptamers, followed by a detailed focus on the aptamers' research against different food allergens broadly based on the major categories of the Big-8 allergens: highlighting the newly screened aptamers and their applied systematic evolution of ligands by exponential enrichment (SELEX) strategies, and emphasizing their practical applications including aptasensors, allergy inhibitors, or affinity adsorptions. Finally, the remaining challenges and future exploitations faced by aptamers in food allergens are comprehensively discussed and depicted. This review holds the promise of inspiring a broader range of researchers to gain an in-depth understanding of food allergy assisted by aptamer recognition and to facilitate improved biochemical analyses and successful application.

Hen's egg white allergy in adults leading to strong impairment of quality of life

In adulthood, hen's egg white allergy (EWA) is a rare condition and rising in prevalence. Typically, EWA begins in early childhood and resolves at school age. Persistence into adulthood or newly onset of the allergy has been reported, but scientific data is scarce. Symptoms reach from typical gastrointestinal problems to severe systemic reactions. EWA and the fear of allergic reactions lead to drastic restrictions in diet as in social life of the affected individuals. This study aims to assess health related quality of life (HRQoL) in adults with EWA using the validated questionnaire "Food Allergy Quality of Life Questionnaire - adult form (FAQoLQ-AF)" and Food Allergy Independent Measure (FAIM). Between July 2023 and October 2023, 16 adults with hen's egg white allergy were identified and questioned using the FAQoLQ-AF to evaluate HRQoL. Patients' characteristics were obtained including age at allergy onset and the most severe allergic symptom. The results were summarized using descriptive statistical analysis. HRQoL was impaired in 16/16 allergic individuals with an overall mean score of 4.64/7 (SD 1.3). Self-assessed emotional impact of the EWA was more problematic than food allergy related health. Food Allergy Independence Measure (FAIM) mean score was 4.64 (SD 1.0) with highest result in product avoidance. The most frequent occurring symptoms were oral allergy syndrome and stomach pain in 7 (44%) patients each. This study shows impaired HRQoL in a small cohort of adults with hen's egg white allergy using the FAQoLQ and FAIM questionnaire with special emphasis on emotional impact. We identified an urgent need for correct food labelling and research into safe treatment options to improve HRQoL.

Hen's egg ladder: Therapy option for the gradual introduction of hen's eggs in cases of hen's egg allergy

More than 10 years ago, the British Society for Allergy and Clinical Immunology (BSACI) published guidelines for the management of egg allergy [1]. For the first time, these included a stepwise plan for the reintroduction of egg for egg-allergic children who could already tolerate well-cooked egg, such as cakes and cookies. Since then, various egg ladders have been developed [2, 3, 4, 5, 6, 7, 8, 9]. In the past 3 years, several studies have been published suggesting that a gradual introduction of highly processed to less processed egg containing foods contribute to the acceleration of tolerance development [2, 3, 4, 5]. However, depending on the study and egg ladder, the egg products vary in their level of processing (wheat matrix, degree, and location of heating (e.g., oven, pan, pot), egg quantity, and egg protein). In the UK, the introduction of the egg ladder is recommended at the age of 12 months or if the last reaction occurred 6 months before. The benefits of introducing egg at home include an early increase in the variety of foods, reduction of food fears, improved nutrient intake, and the avoidance of hospitalization fears in children [10]. Children with mild reactions in the past can start with small amounts of baked goods at home. Food challenges in an inpatient setting to exclude or reconfirm the allergy should be conducted if the patients have previously had severe allergic reactions, i.e., anaphylaxis, or if the smallest amounts triggered an allergic reaction or if existing asthma is poorly controlled [10, 11]. The present work includes, in addition to the evaluation of study results, a presentation of the recent studies regarding egg ladders. From these, a new egg ladder as therapeutic option for the German-speaking region has been developed. As already done for the milk ladder a detailed step-by-step plan, selection criteria, a recipe collection, and also ideas for commercial prepackaged food items can be found in the appendices [11].

Baked Egg Oral Immunotherapy: Current State in Pediatric Age

Hen's egg allergy is one of the most common food allergies in the Western world, with an increase in recent years. It affects about 9.5% of the pediatric population, and the onset most often occurs before the first year of life. The occurrence of spontaneous oral tolerance acquisition varies among studies, but it is generally high by school age. Nowadays, allergen immunotherapy may represent the only therapeutic strategy able to modify the natural history of hen's egg allergy. Specifically, many children with hen's egg allergy may tolerate baked eggs. Food processing, specifically high temperatures, alters the allergenicity of hen's egg proteins by causing conformational changes in allergen epitopes, which makes them less allergenic. This review aims to discuss the scientific evidence in the field of baked egg oral immunotherapy in hen's egg-allergic children, with a meticulous examination of the pertinent literature surrounding the subject matter.

Practical experience of allergy to egg proteins clinical manifestation

Food allergy occupies a significant place among disorders that impair the quality of patients’ lives, bringing a large number of restrictions to their diet and lifestyle. Therefore, the purpose of this study is to examine the clinical features of allergy to chicken eggs with the determination of key trends in diagnosis and treatment. A descriptive and comparative analysis of three cases was carried out with a large-scale assessment of specific Immunoglobulins E (IgE), determined by the enzyme-linked immunosorbent assay. It becomes clear, that due to the high prevalence of allergy to white and yolk of chicken eggs in the general population (among the Polish population including), chicken eggs have severe allergenic characteristics and may display various symptoms that may be problematic to differentiate. The patients from the presented cases were characterized by a severe course of the disease – minimal consumption of chicken eggs led to the development of urticaria, swelling of the eyelids, and bronchospasm, which required urgent administration of adrenaline and hospitalization. For the purpose of diagnosis, patients with anaphylactic reactions are highly restricted, because methods of skin prick testing, and provocation tests (oral and nasal) are contraindicated. In this regard, molecular diagnostics and the determination of specific immunoglobulins E for ovalbumin, ovomucoid, and other glycoproteins are recommended. This research can lead to the creation of purified recombinant allergens for use in the process of diagnosis and treatment, as well as in the food industry, also, it emphasizes the introduction of preventive measures for the development of anaphylaxis.

Dietary Advancement Therapy Using Milk and Egg Ladders Among Children With a History of Anaphylaxis

BACKGROUND

Anaphylaxis has been increasing in recent years, with common triggers in infants being milk and eggs. Currently, the mainstay of treatment for milk and/or egg allergy is strict avoidance. Recently, new therapies have emerged including stepwise introduction of allergens via a ladder approach. The suitability of infants for the ladders is debated.

OBJECTIVE

This study aims to focus on the use of food ladders in children with anaphylaxis to egg or milk.

METHODS

Retrospective review of pediatric patients diagnosed with immunoglobulin E-mediated milk and/or egg allergy between 2011 and 2021. Inclusion and exclusion criteria were applied. Anaphylaxis was defined as per the World Allergy Organization-amended criteria 2020. Data analysis utilized SPSS Version 28.

RESULTS

We reviewed 1,552 patient charts, and excluded 1,094, leaving a total sample size of 458. Seventy infants had anaphylaxis at diagnosis (milk n = 36; egg n = 34). A range of 77.8% to 85.2% of infants with anaphylaxis successfully completed the ladder, 88.9% to 92.9% without anaphylaxis were successful. Children who successfully completed the ladder did so at similar rates. A range of 20.6% to 50% children presenting with anaphylaxis at diagnosis experienced allergic symptoms during treatment, compared with 17.3% to 40.7% without anaphylaxis. Reactions were mild, mostly cutaneous and not requiring medical attention. Patients experiencing allergic symptoms while on the ladder were less likely to successfully complete treatment.

CONCLUSIONS

Milk and egg ladders are a safe and effective way of inducing tolerance in infants, including those with a history of anaphylaxis at diagnosis. There are no obvious predictors for who will experience allergic reactions while on the ladder; however, these children are less likely to complete the ladder, so parents should be educated in management of mild allergic reactions at home.

Ovalbumin promotes innate immune response of Caenorhabditis elegans through DAF-16 and SKN-1 pathways in insulin/IGF-1 signaling

Ovalbumin (OVA) is a major allergen in eggs and could induce severe allergic reactions in sensitive individuals, where the innate immune system works as a regulator. The mechanism of how innate immunity adjusts to food allergy is relatively well-studied, however, the effects of allergen uptake on the innate immune system remain unclear. Therefore, the Caenorhabditis elegans (C. elegans) model was utilized to assess the effects of OVA on its innate immune system. OVA enhanced the immune response of C. elegans with higher survival rates under Pseudomonas aeruginosa infection. Moreover, sustaining OVA treatment improved the health states that were reflected in the prolonged lifespan, alleviated oxidative stress, accelerated growth, and promoted motility. RNA-sequencing analysis and the slow-killing assays in the mutants of insulin/IGF-1 signaling (IIS)-related genes confirmed that IIS was necessary for OVA to regulate innate immunity. Besides, OVA activated SKN-1 temporarily and facilitated the nuclear localization of DAF-16 for improving immunity and health status in C. elegans. Together, OVA could enhance the innate immune responses via DAF-16 and SKN-1 pathways in the IIS of C. elegans, and this work will provide novel insights into the regulation of innate immunity by OVA in higher organisms.

Traditional cooking methods decreased the allergenicity of egg proteins

Egg allergy is one of the most common food allergies globally. This study aimed to assess the impact of four traditional cooking methods on the allergenicity of egg proteins using a comprehensive strategy, including simulated gastrointestinal digestion in vitro, serology experiments, a rat basophilic leukemia (RBL)-2H3 cell degranulation model, and a passive cutaneous anaphylaxis (PCA) mice model, and the structure changes were detected by circular dichroism (CD) spectra and ultraviolet (UV) spectra. The results showed that the processed egg proteins were more readily digested compared to raw egg proteins. The serological experiments revealed a significant reduction in immunoglobulin E binding of egg proteins after thermal treatments (p < 0.05), particularly after frying. Subsequently, the RBL-2H3 cell degranulation experiment demonstrated a marked decrease in the level of egg allergens-induced β-hexosaminidase release after cooking (p < 0.05). Moreover, the results from the PCA mice model indicated that the increase in vascular permeability was effectively relieved in the treated groups, especially in frying group (p < 0.05). Additionally, the α-helix and β-turn contents of processed egg proteins were significantly decreased (p < 0.05) compared with native egg proteins. The UV spectra findings showed that all cooking treatments caused significant alterations in the tertiary structure, and fluorescence analysis indicated that cooking decreased the surface hydrophobicity of egg proteins. In conclusion, four traditional cooking methods reduced the allergenicity of egg proteins, particularly frying, and this reduction was associated with structural changes that could contribute to the destruction or masking of epitopes of egg allergens. PRACTICAL APPLICATION: Egg allergy has a serious impact on public health, and there is no ideal treatment method at present. This study demonstrated that four traditional cooking methods (boiling, steaming, baking, and frying) reduced the allergenicity of egg proteins, especially frying, and the results will provide a basis for the development of hypoallergenic egg products.

Animal-derived food allergen: A review on the available crystal structure and new insights into structural epitope

Immunoglobulin E (IgE)-mediated food allergy is a rapidly growing public health problem. The interaction between allergens and IgE is at the core of the allergic response. One of the best ways to understand this interaction is through structural characterization. This review focuses on animal-derived food allergens, overviews allergen structures determined by X-ray crystallography, presents an update on IgE conformational epitopes, and explores the structural features of these epitopes. The structural determinants of allergenicity and cross-reactivity are also discussed. Animal-derived food allergens are classified into limited protein families according to structural features, with the calcium-binding protein and actin-binding protein families dominating. Progress in epitope characterization has provided useful information on the structural properties of the IgE recognition region. The data reveals that epitopes are located in relatively protruding areas with negative surface electrostatic potential. Ligand binding and disulfide bonds are two intrinsic characteristics that influence protein structure and impact allergenicity. Shared structures, local motifs, and shared epitopes are factors that lead to cross-reactivity. The structural properties of epitope regions and structural determinants of allergenicity and cross-reactivity may provide directions for the prevention, diagnosis, and treatment of food allergies. Experimentally determined structure, especially that of antigen-antibody complexes, remains limited, and the identification of epitopes continues to be a bottleneck in the study of animal-derived food allergens. A combination of traditional immunological techniques and emerging bioinformatics technology will revolutionize how protein interactions are characterized.

An integrated calibration strategy for the development and validation of an LC-MS/MS method for accurate quantification of egg allergens (Gal d 1-6) in foods

Accurate determination of egg allergens in food is vital for allergen management and labeling. However, quantifying egg allergens with mass spectrometry poses challenges and lacks validation methods. Here, we developed and validated an LC-MS/MS method for quantifying egg allergens (Gal d 1-6) in foods. Sample extraction, enzymatic digestion, purification, proteins/peptides selection, and calibration curves were optimized. VMVLC[+57]NR (Gal d 1) and GTDVQAWIR (Gal d 5) exhibited outstanding sensitivity and stability, serving as quantitation markers for egg white and yolk. Using a matrix-matched calibration curve with allergen ingredients as calibrants and labeled peptides as standards, we achieved highly accurate quantitation. Validation involved spiking egg protein into egg-free foods, showing excellent sensitivity (LOQ: 1-5 mg/kg), accuracy (62.4 %-88.5 %), and reproducibility (intra-/inter-day precision: 3.5 %-14.2 %/8.2 %-14.6 %). Additionally, we successfully applied this method to commercial food analysis. These findings demonstrate optimal allergen selection, peptides, and calibration strategy are crucial parameters for food allergen quantification via MS-based methods.

Tackling food allergens-The role of food processing on proteins' allergenicity

This chapter examines how innovative and emerging food processing technologies, such as those that use heat, electricity, electromagnetic waves, and pressure, can modify protein denaturation, aggregation, and intermolecular interactions pathways, which can result in varying immunoreactive responses. It emphasizes the need to understand how these processing methods affect the protein epitopes recognized by antibodies and their respective priming pathways, especially during the sensitization stage that precedes an allergic response. Although traditional processing methods have been investigated, the impact of novel technologies on food protein allergenicity remains largely unknown. The chapter specifically focuses on milk proteins, which have clinical significance and are associated with cow's milk allergy, one of the most common food allergies in young children. Additionally, it examines potential scientific advancements that novel processing methods may bring to this field.

Methodological Principles of Nasal Food Challenge

Thanks to their valuable assessment possibilities (subjective complaints and changes in nasal patency during the examination), nasal provocation tests may serve as an alternative tool for oral food challenges in the future. However, this test requires successive attempts to regulate its methodology in order to develop a standardized lyophilisate form and determine the threshold dose for a positive result. The study objective was to present the methodological foundation for nasal food allergen provocation tests induced by freeze-dried powdered chicken egg whites. A control group of 25 individuals with no history of allergy to chicken eggs or any other allergy was included in the study. Optical rhinometry and visual analog scales were used to assess the response of nasal mucosa to local allergen challenges. Minor variations in nasal flows, as measured by optical rhinometry, were observed in the provocation tests. The mean optical density measurements (as measured regardless of the allergen dose used) varied from positive to negative values and vice versa, e.g., amounting to 0.018 OD (standard deviation 0.095) at 15 min and -0.011 OD (standard deviation 0.090) at 30 min. No significant differences were observed concerning the perceived nasal discomfort using the visual analog scale. Due to the absence of nasal mucosal reactivity, nasal challenge is an excellent methodological tool for implementing food allergen tests.

Oral and nasal provocation test in chicken egg allergy-case report

INTRODUCTION

Allergy to chicken egg protein is a common form of food allergy. The most common clinical presentation includes gastrointestinal, skin, and respiratory symptoms. Differential diagnosis, including provocative tests, is critical in diagnosis.

CASE DESCRIPTION

We present a case of a 21-year-old patient with egg allergy, who underwent a double-blind food provocation test with placebo (evaluating subjective complaints from the gastrointestinal tract) and a titrated nasal provocation test using dry chicken egg content. We assessed the response of the nasal mucosa in the provocation test using the visual analogue scale (VAS), acoustic and optical rhinometry, as well as measurements of nitric oxide concentration in the exhaled air. During the provocation test, we measured the changes in the transverse section of the nasal passages, which were accompanied by subjective complaints measured with the VAS scale, using objective techniques. In the nasal provocation test with a dose of 20 µg of chicken egg protein, we observed an increase in the reactivity of the nasal mucosa and a decrease in the level of nitric oxide in the exhaled air from the upper airways (920 ppb before the provocation test and up to 867 ppb during the early stage of the allergic reaction). During the provocation tests, we recorded typical symptoms associated with the early stage of the allergic reaction; including nasal obstruction (1.2 cm), leakage of watery discharge (0.8 cm) in the food test, and itchy nose (1.1 cm) in the food test vs. the nasal test: 4.6, 2.8, and 3.5 cm, respectively.

CONCLUSIONS

The nasal mucosa provides convenient conditions for evaluation of the severity of allergy to common food allergens, including chicken egg allergens.

Proteomic investigation and understanding on IgY purification and product development

An increasing demand for the development of immunoglobin Y (IgY) illustrates the necessity of the component analysis in the process of conduction and quality control. This study investigated the proteomic changes in crude IgY extracts and purified IgY products obtained by sequential polyethylene glycol precipitation (PEG) of egg yolks followed by human mycoplasma protein-based affinity chromatography compared with intact egg yolks. After confirming the extraction efficiency and purity by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis, liquid chromatography tandem-mass spectrometry (LC-MS/MS) was performed with samples including fresh yolk, IgY extracted product and purified product. A total of 348 proteins were identified, with 36 proteins deleted and 209 newly detected proteins in the purified product compared to the intact egg yolk. The significantly decreased proteins mainly included phosvitin, albumin, and apolipoprotein B whereas the significantly increased proteins were mainly IgY-related proteins. GO analysis showed that the purified IgY product had ATPase activity and purine ribonucleoside triphosphate binding activity, and was mainly involved in purine and nucleic acid metabolism. This study will inevitably fasten the commercial application of IgY antibodies and is of greater significance for promotion, development and approval for new antibody derived drug products.

The role of basophil activation test and component-resolved diagnostics in the workup of egg allergy in children at low risk for severe allergic reactions: A real-life study

BACKGROUND

The gold standard for diagnosing egg allergy in children is the oral food challenge (OFC). However, OFCs are time-consuming and risky procedures. Our study aimed to evaluate the utility of the basophil activation test (BAT) and component-resolved diagnostic in the diagnostic workup of children with egg allergy.

METHODS

Overall, 86 children aged 6 months to 17 years, suspected of egg allergy, underwent OFC with boiled egg according to international standardized protocols. BAT and specific immunoglobulin E (sIgE) testing to component egg proteins (Gal d 1-4) were also performed.

RESULTS

Of the 22 children who reacted to boiled egg, only one experienced anaphylaxis during the challenge. BAT was performed in samples obtained by 75 of the 86 patients of our cohort. Egg white and yolk protein extracts induced CD63 upregulation in the egg-allergic (EA) children compared with sensitized children that tolerated boiled egg (we registered an overall mean of CD63 expression in the EA population of 44.4% [SD 34.1] for egg white and 34.7% [SD 31.3] for egg yolk vs. 12.5% [SD 19.1] and 10.0% [SD 16.0] in sensitized children). BAT could discriminate between true egg allergy and egg sensitization in our population. As a second-line diagnostic step, the positivity of BAT for egg white or Gal d 1-sIgE resulted in a 40.9% OFC reduction, especially for those with a positive outcome.

CONCLUSION

The BAT may be implemented in the diagnostic workup of egg allergy in children and, in a stepwise approach, separately or combined with Gal d 1-sIgE, may predict the allergic status and reduce the number of positive OFCs in children with egg allergy at low risk for severe reactions.

Advanced Proteomic and Bioinformatic Tools for Predictive Analysis of Allergens in Novel Foods

In recent years, novel food is becoming an emerging trend increasingly more demanding in developed countries. Food proteins from vegetables (pulses, legumes, cereals), fungi, bacteria and insects are being researched to introduce them in meat alternatives, beverages, baked products and others. One of the most complex challenges for introducing novel foods on the market is to ensure food safety. New alimentary scenarios drive the detection of novel allergens that need to be identified and quantified with the aim of appropriate labelling. Allergenic reactions are mostly caused by proteins of great abundance in foods, most frequently of small molecular mass, glycosylated, water-soluble and with high stability to proteolysis. The most relevant plant and animal food allergens, such as lipid transfer proteins, profilins, seed storage proteins, lactoglobulins, caseins, tropomyosins and parvalbumins from fruits, vegetables, nuts, milk, eggs, shellfish and fish, have been investigated. New methods for massive screening in search of potential allergens must be developed, particularly concerning protein databases and other online tools. Moreover, several bioinformatic tools based on sequence alignment, motif identification or 3-D structure predictions should be implemented as well. Finally, targeted proteomics will become a powerful technology for the quantification of these hazardous proteins. The ultimate objective is to build an effective and resilient surveillance network with this cutting-edge technology.

Cross-reactive epitopes and their role in food allergy

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

Epitope Mapping of Lysozyme Using the Chinese Egg-Allergic Sera at Both Pooled and Individual Levels

To accurately map the B-cell linear epitopes of lysozyme (LYS) in eggs, five bioinformatics tools were first used to obtain the mimotopes. Afterward, based on the Chinese egg-allergic sera samples screened by the indirect enzyme-linked immunosorbent, the epitopes possessing the capability of binding to IgG/IgE were mapped at both pooled and individual levels by using overlapping peptides covering the complete amino acid sequence of LYS. Six B-cell linear epitopes and two dominant B-cell linear epitopes that could bind to LYS-sIgG were mapped for the first time. Seven IgE-binding epitopes and three dominant IgE-binding epitopes were also obtained. Furthermore, AA31-34 and AA88-91 were the shared dominant epitopes of LYS-sIgG and LYS-sIgE at pooled and individual levels. Overall, the mapped B-cell linear epitopes filled in the gaps in the study of LYS epitopes, and the results may provide theoretical support for the following immunotherapy of egg allergy.

The Impact of Processing and Extraction Methods on the Allergenicity of Targeted Protein Quantification as Well as Bioactive Peptides Derived from Egg

This review article discusses advanced extraction methods to enhance the functionality of egg-derived peptides while reducing their allergenicity. While eggs are considered a nutrient-dense food, some proteins can cause allergic reactions in susceptible individuals. Therefore, various methods have been developed to reduce the allergenicity of egg-derived proteins, such as enzymatic hydrolysis, heat treatment, and glycosylation. In addition to reducing allergenicity, advanced extraction methods can enhance the functionality of egg-derived peptides. Techniques such as membrane separation, chromatography, and electrodialysis can isolate and purify specific egg-derived peptides with desired functional properties, improving their bioactivity. Further, enzymatic hydrolysis can also break down polypeptide sequences and produce bioactive peptides with various health benefits. While liquid chromatography is the most commonly used method to obtain individual proteins for developing novel food products, several challenges are associated with optimizing extraction conditions to maximize functionality and allergenicity reduction. The article also highlights the challenges and future perspectives, including optimizing extraction conditions to maximize functionality and allergenicity reduction. The review concludes by highlighting the potential for future research in this area to improve the safety and efficacy of egg-derived peptides more broadly.

Research advance of non-thermal processing technologies on ovalbumin properties: The gelation, foaming, emulsification, allergenicity, immunoregulation and its delivery system application

Ovalbumin (OVA) is the most abundant protein in egg white, with excellent functional properties (e.g., gelling, foaming, emulsifying properties). Nevertheless, OVA has strong allergenicity, which is usually mediated by specific IgE thus results in gut microbiota dysbiosis and causes atopic dermatitis, asthma, and other inflammation actions. Processing technologies and the interactions with other active ingredients can influence the functional properties and allergic epitopes of OVA. This review focuses on the non-thermal processing technologies effects on the functional properties and allergenicity of OVA. Moreover, the research advance about immunomodulatory mechanisms of OVA-mediated food allergy and the role of gut microbiota in OVA allergy was summarized. Finally, the interactions between OVA and active ingredients (such as polyphenols and polysaccharides) and OVA-based delivery systems construction are summarized. Compared with traditional thermal processing technologies, novel non-thermal processing techniques have less damage to OVA nutritional value, which also improve OVA properties. OVA can interact with various active ingredients by covalent and non-covalent interactions during processing, which can alter the structure or allergic epitopes to affect OVA/active components properties. The interactions can promote OVA-based delivery systems construction, such as emulsions, hydrogels, microencapsulation, nanoparticles to encapsulate bioactive components and monitor freshness for improving foods quality and safety.

Advances in the Study of Probiotics for Immunomodulation and Intervention in Food Allergy

Food allergies are a serious food safety and public health issue. Soybean, dairy, aquatic, poultry, and nut products are common allergens inducing allergic reactions and adverse symptoms such as atopic dermatitis, allergic eczema, allergic asthma, and allergic rhinitis. Probiotics are assumed as an essential ingredient in maintaining intestinal microorganisms' composition. They have unique physiological roles and therapeutic effects in maintaining the mucosal barrier, immune function, and gastrointestinal tract, inhibiting the invasion of pathogenic bacteria, and preventing diarrhea and food allergies. Multiple pieces of evidence reveal a significant disruptive effect of probiotics on food allergy pathology and progression mechanisms. Thus, this review describes the allergenic proteins as an entry point and briefly describes the application of probiotics in allergenic foods. Then, the role of probiotics in preventing and curing allergic diseases by regulating human immunity through intestinal flora and intestinal barrier, modulating host immune active cells, and improving host amino acid metabolism are described in detail. The anti-allergic role of probiotics in the function and metabolism of the gastrointestinal tract has been comprehensively explored to furnish insights for relieving food allergy symptoms and preventing food allergy.

Hepatoprotective Effects of Rosmarinic Acid on Ovalbumin-Induced Intestinal Food Allergy Mouse Model

Rosmarinic acid (RA) has been proven to exert antianaphylaxis in atopic dermatitis, asthma, and allergic rhinitis. The aim of this study was to determine the hepatoprotective effects of RA on ovalbumin (OVA) challenge-induced intestinal allergy. The results exhibited that RA could relieve anaphylactic symptoms, decrease diarrhea, and prevent hypothermia in allergic mice. Moreover, the elevation of OVA specific IgE (OVA-sIgE), histamine, and mouse mast cell proteinases (mMCP-1) in the serum of OVA challenged mice were remarkably inhibited by RA. OVA challenge resulted in notable increases in serum alanine aminotransferase (ALT), aspartate aminotransferase (AST) activities, liver malondialdehyde (MDA) and nitic oxide (NO) levels, and a remarkable decrease in liver superoxide dismutase (SOD) activity and glutathione (GSH) level. RA treatments succeeded in improving these biochemical parameters and promote the redox homeostasis. Cytokine expression evaluation showed that RA effectively enhanced the expression of anti-inflammatory cytokines (IL-10 and FOXP-3) in the liver of OVA-challenged mice. Meanwhile, the elevation of pro-inflammatory cytokines (TNF-α, IL-4, IL-6, mMCP-1, and iNOS) were remarkably inhibited by RA. These findings suggest that RA possesses hepatoprotective effects on OVA challenge-induced liver injury. The anti-oxidative and anti-inflammatory activities of RA potentially play vital roles in this process.

Identification of the Immunoglobulin E Epitope of Arginine Kinase, an Important Allergen from Crassostrea angulata

Arginine kinase (AK) was identified as an allergen in Crassostrea angulata. However, little information is available about its epitopes. In this study, AK from C. angulata was registered to the World Health Organization/International Union of Immunological Societies allergen nomenclature committee to be named as Cra a 2. The immunoglobulin G/immunoglobulin E-binding capacity of Cra a 2 was significantly reduced after chemical denaturation treatment. Further, eight linear mimotopes and five conformational mimotopes of Cra a 2 were obtained using phage panning. In addition to six linear epitopes that have been identified, two linear epitopes were verified by a synthetic peptide, of which L-Cra a 2-2 was conserved in shellfish. Four conformational epitopes were verified by site-directed mutation, among which mutation of C-Cra a 2-1 affected the structure and reduced the immunoreactivity of Cra a 2 most significantly. Overall, the identified epitopes may lay a foundation for the development of hypoallergenic oyster products through food processing.

Poultry Meat allergy: a Review of Allergens and Clinical Phenotypes

Purpose of review

In the recent years, more cases of poultry meat allergy, both IgE- or non-IgE-mediated, are being reported. Patients have varied clinical reactivity at various levels of sensitivity to different meat preparations. The lack of validated biomarkers renders accurate diagnosis challenging. In this review, we aim to provide an overview of the current status of poultry meat allergy along with a description on the allergens implicated.

Recent findings

Poultry meat allergy occurs as a result of cross-reactions with known allergens of egg yolk or bird feathers or as genuine IgE-mediated sensitivity to allergens in poultry meat. Individuals can also develop non-IgE-mediated hypersensitivity reactions to poultry meat. Chicken serum albumin is the main responsible allergen in secondary cases, while myosin light chain, α parvalbumin, enolase, aldolase, hemoglobin, and α-actin have been recognized as potential eliciting allergens in genuine poultry meat allergy.

Summary

There is a wide phenotypic variation among patients with poultry meat allergy, regarding clinical severity and cross-reactivity features. Recognizing the various clinical entities of reactions to poultry meat is an important step towards accurate diagnosis and providing management options that are well received by patients.

Performance evaluation of a laboratory-developed light-initiated chemiluminescence assay for quantification of egg white-specific IgE

Background

Specific IgE (sIgE) testing has become one of the most important tools for diagnosing IgE‐mediated food allergy. Enzyme‐linked immunosorbent assay (ELISA) and dot‐enzyme‐linked immunosorbent assay (Dot‐ELISA) have been used to measure sIgE in clinical widely. Light‐initiated chemiluminescence assay (LICA) is a new method for measuring allergen‐sIgE. We aimed to establish a LICA method for quantitative detection of egg white‐sIgE and evaluate its performances.

Methods

The best chemibeads coupling method in detecting egg white‐sIgE was selected, and a LICA method for quantitative detection of egg white‐sIgE was established. The precision study was performed according to Clinical and Laboratory Standards Institute (CLSI) EP5‐A2. Detection capability which contains limit of blank (LoB), limit of detection (LoD), and limit of quantitation (LoQ) was evaluated according to National Health Commission of the People's Republic of China (NHC) WS/T 514–2017. Linear range was evaluated according to CLSI EP6‐A. All data were analyzed using SPSS software.

Results

Precision contains repeatability and intermediate precision. The CV of repeatability ranged from 2.72% to 7.29%, and the CV of intermediate precision ranged from 4.93% to 8.64%. The LoB, LoD, and LoQ of the assay were 0.000 kUA/L, 0.053 kUA/L, and 0.076 kUA/L. The assay linear range was 0.076–34.125 kU_A/L (r = 0.9979 ≥ 0.9900).

Conclusion

This laboratory‐developed LICA method can detect egg white‐sIgE, and performance meets clinical requirements. This method shows rapid turnaround cycles and high sensitivity. It can be used as an alternative method for clinical detection of egg white‐sIgE.

Suppression of Airway Allergic Reactions by a Photocatalytic Filter Using Mouse Model

Photocatalytic filters installed in air purifiers have been used to purify spaces by decomposing allergenic substances. However, we have not found any reports that evaluate the effectiveness of photocatalytic filters in suppressing allergic reactions in living organisms. In this study, we intratracheally instilled ovalbumin (OVA) into OVA-sensitized mice after the OVA was photocatalyzed by a titanium dioxide (TiO₂) filter, and verified the experimental model for evaluating the allergy-suppressing effect of photocatalysts. Mice were sensitized to OVA (10 µg/mouse) four times, and were intratracheally instilled with OVA (10 µg/mouse) after photocatalysis three times. Non-sensitized animals were instilled with normal saline following the same exposure schedule. The mice were dissected 24 h after final exposure. The OVA after photocatalysis significantly decreased the number of eosinophils in bronchoalveolar lavage fluid, and the concentration of OVA-specific IgE and IgG1 in serum, which were elevated in untreated OVA. Moreover, our experimental model showed the suppression of allergic reactions in mice, along with the decomposition of OVA after photocatalysis using the photocatalytic filter. Taken together, our experimental model for evaluating allergic reactions in the respiratory tract suggested that the allergy-suppressing effect of the photocatalytic filter can be evaluated.

Aptamer-Based Fluorescent Biosensor for the Rapid and Sensitive Detection of Allergens in Food Matrices

Food allergies have seriously affected the life quality of some people and even endangered their lives. At present, there is still no effective cure for food allergies. Avoiding the intake of allergenic food is still the most effective way to prevent allergic diseases. Therefore, it is necessary to develop rapid, accurate, sensitive, and reliable analysis methods to detect food allergens from different sources. Aptamers are oligonucleotide sequences that can bind to a variety of targets with high specificity and selectivity, and they are often combined with different transduction technologies, thereby constructing various types of aptamer sensors. In recent years, with the development of technology and the application of new materials, the sensitivity, portability, and cost of fluorescence sensing technology have been greatly improved. Therefore, aptamer-based fluorescence sensing technology has been widely developed and applied in the specific recognition of food allergens. In this paper, the classification of major allergens and their characteristics in animal and plant foods were comprehensively reviewed, and the preparation principles and practical applications of aptamer-based fluorescence biosensors are summarized. In addition, we hope that this article can provide some strategies for the rapid and sensitive detection of allergens in food matrices.

Genetically engineered birds; pre-CRISPR and CRISPR era

Generating biopharmaceuticals in genetically engineered bioreactors continues to reign supreme. Hence, genetically engineered birds have attracted considerable attention from the biopharmaceutical industry. Fairly recent genome engineering methods have made genome manipulation an easy and affordable task. In this review, we first provide a broad overview of the approaches and main impediments ahead of generating efficient and reliable genetically engineered birds, and various factors that affect the fate of a transgene. This section provides an essential background for the rest of the review, in which we discuss and compare different genome manipulation methods in the pre-CRISPR and CRISPR era in the field of avian genome engineering.

Adult onset egg allergy: a case report

BACKGROUND

Egg allergy is one of the most frequent food allergies in childhood while adult onset of egg allergy is a rare condition.

CASE PRESENTATION

We report the case of a 30 years old man sent to our center in order to investigate gastrointestinal symptoms occurring since 2 years after egg and derivatives intake. He did not suffer from egg or other food allergies in childhood. He is an active smoker with a contact dermatitis related to nickel and mild allergic rhinoconjunctivitis to grass pollen. Skin prick test and serum specific IgE to egg were performed and revealed sensitization to egg proteins.

CONCLUSIONS

Even though IgE-mediated egg allergy affects children, this report witnesses a rare case of adult onset.

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.

Effect of processing technologies on the digestibility of egg proteins

Egg and egg products are a rich source of highly bioavailable animal proteins. Several processing technologies can affect the structural and functional properties of these proteins differently and can influence their fate inside the gastrointestinal tract. The present review examines some of the processing technologies for improving egg protein digestibility and discusses how different processing conditions affect the digestibility of egg proteins under gastrointestinal digestion environments. To provide up-to-date information, most of the studies included in this review have been published in the last 5 years on different aspects of egg protein digestibility. Digestibility of egg proteins can be improved by employing some processing technologies that are able to improve the susceptibility of egg proteins to gastrointestinal proteases. Processing technologies, such as pulsed electric field, high-pressure, and ultrasound, can induce conformational and microstructural changes that lead to unfolding of the polypeptides and expose active sites for further interactions. These changes can enhance the accessibility of digestive proteases to cleavage sites. Some of these technologies may inactivate some egg proteins that are enzyme inhibitors, such as trypsin inhibitors. The underlying mechanisms of how different technologies mediate the egg protein digestibility have been discussed in detail. The proteolysis patterns and digestibility of the processed egg proteins are not always predictable and depends on the processing conditions. Empirical input is required to tailor the optimization of processing conditions for favorable effects on protein digestibility.

Processes for reducing egg allergenicity: Advances and different approaches

Egg is a versatile ingredient and ubiquitous food. Nevertheless, egg proteins are a common cause of allergy mainly in childhood. Until now, egg eviction has been the best way to prevent this disorder, however, processed food can contribute to mitigate allergies and to guarantee life quality of allergic individuals. This review focuses on discussing and highlighting recent advances in processes to reduce egg allergenicity as well as new approaches to egg allergy management. In recent times, different methods have been developed to reduce egg allergies, by hiding the epitopes or changing the native or conformational structure of the proteins. Despite processing food has not yet been a solution to completely remove the allergenic potential of egg proteins, innovative strategies, such as addition of phenolic compounds, have been developed with promising results.