Deamidation and Enzymatic Hydrolysis of Gliadins Alter Their Processing by Dendritic Cells in Vitro

Higher Potential Sensitization of Cow αS1-Casein over Goat αS1-Casein in a Mouse Model due to Enhanced Dendritic Cell Uptake and Activation

Cow's milk allergy is a common food allergy, with the milk protein αS1-casein being a major allergen. This study aimed to investigate differences in sensitization between cow and goat αS1-CN. Cow and goat αS1-CN were labeled with fluorescent dyes and given to mice sensitized with cholera toxin adjuvant. Both proteins reached immune organs, suggesting no major difference in digestion. However, compared with goat αS1-CN, cow αS1-CN is more readily taken up by dendritic cells, inducing dendritic cell maturation. Furthermore, cow αS1-CN can more effectively induce the generation of Th2 cells, leading to a higher production of specific IgE. In a Caco-2/RBL-2H3 cell model, cow αS1-CN caused more mast cell degranulation and loss of epithelial barrier integrity than goat αS1-CN. In summary, this study found differences in immune responses between cow and goat milk αS1-CN. Cow αS1-CN elicited stronger dendritic cell and Th2 responses, leading to increased mast cell degranulation.

Oral exposure to Staphylococcus aureus enterotoxin B could promote the Ovalbumin-induced food allergy by enhancing the activation of DCs and T cells

Introduction

Recent work highlighted the importance of environmental contaminants in the development of allergic diseases.

Methods

The intestinal mucosal barrier, Th (helper T) cells, DCs (dendritic cells), and intestinal flora were analyzed with flow cytometry, RNA-seq, and 16s sequencing in the present study to demonstrate whether the exposure of enterotoxins like Staphylococcus aureus enterotoxin B (SEB) in allergens could promote the development of food allergy.

Results and discussion

We found that co-exposure to SEB and Ovalbumin (OVA) could impair the intestinal barrier, imbalance the intestinal Th immune, and cause the decline of intestinal flora diversity in OVA-sensitized mice. Moreover, with the co-stimulation of SEB, the transport of OVA was enhanced in the Caco-2 cell monolayer, the uptake and presentation of OVA were promoted in the bone marrow dendritic cells (BMDCs), and Th cell differentiation was also enhanced. In summary, co-exposure to SEB in allergens should be considered a food allergy risk factor.

Allergenicity of wheat protein in diet: Mechanisms, modifications and challenges

Wheat is widely available in people's daily diets. However, some people are currently experiencing IgE-mediated allergic reactions to wheat-based foods, which seriously impact their quality of life. Thus, it is imperative to provide comprehensive knowledge and effective methods to reduce the risk of wheat allergy (WA) in food. In the present review, recent advances in WA symptoms, the major allergens, detection methods, opportunities and challenges in establishing animal models of WA are summarized and discussed. Furthermore, an updated overview of the different modification methods that are currently being applied to wheat-based foods is provided. This study concludes that future approaches to food allergen detection will focus on combining multiple tools to rapidly and accurately quantify individual allergens in complex food matrices. Besides, biological modification has many advantages over physical or chemical modification methods in the development of hypoallergenic wheat products, such as enzymatic hydrolysis and fermentation. It is worth noting that using biotechnology to edit wheat allergen genes to produce allergen-free food may be a promising method in the future which could improve the safety of wheat foods and the health of allergy sufferers.

Antigen presentation induced variation in ovalbumin sensitization between chicken and duck species

The difference in the allergenicity of chicken ovalbumin (C-OVA) and duck ovalbumin (D-OVA) can be related to their differences in antigen presentation. This study explored the differences in uptake between C-OVA and D-OVA through fluorescence dye-labeling, DC antigen presentation, and the immune response of T cells by using C-OVA and D-OVA allergic animal and cell models. The ileum DCs of mice in the C-C group took up more C-OVA than that of D-D and C-D groups through in vivo imaging. Furthermore, C-OVA induced the maturation of DCs in mice in the C-C group as shown in the up-regulation of the expressions of MHC II, CD86 and CD80 on the surface of DCs, and enhanced the ability of antigen presentation. In addition, C-OVA induced the maturation of DCs, promoted the differentiation of T cells into Th2 cells, increased the secretion of the cytokine IL-4 and specific antibody s-IgE, and thus generated an immune response. However, sensitized and cross sensitized D-OVA (D-D and C-D groups) couldn't induce the maturation of DCs, and induced less differentiation of T cells and lower secretion of cytokines compared to C-OVA. In conclusion, the differences in antigen presentation was one of the important factors resulting in the differences in the sensitization between C-OVA and D-OVA.

Acid Hydrolysis of Gluten Enhances the Skin Sensitizing Potential and Drives Diversification of IgE Reactivity to Unmodified Gluten Proteins

SCOPE

Personal care products containing hydrolyzed gluten have been linked to spontaneous sensitization through the skin, however the impact of the hydrolysate characteristics on the sensitizing capacity is generally unknown.

METHODS AND RESULTS

The physicochemical properties of five different wheat-derived gluten products (one unmodified, one enzyme hydrolyzed, and three acid hydrolyzed) are investigated, and the skin sensitizing capacity is determined in allergy-prone Brown Norway rats. Acid hydrolyzed gluten products exhibited the strongest intrinsic sensitizing capacity via the skin. All hydrolyzed gluten products induced cross-reactivity to unmodified gluten in the absence of oral tolerance to wheat, but were unable to break tolerance in animals on a wheat-containing diet. Still, the degree of deamidation in acid hydrolyzed products is associated with product-specific sensitization in wheat tolerant rats. Sensitization to acid hydrolyzed gluten products is associated with a more diverse IgE reactivity profile to unmodified gluten proteins compared to sensitization induced by unmodified gluten or enzyme hydrolyzed gluten.

CONCLUSION

Acid hydrolysis enhances the skin sensitizing capacity of gluten and drives IgE reactivity to more gluten proteins. This property of acid hydrolyzed gluten may be related to the degree of product deamidation, and could be a strong trigger of wheat allergy in susceptible individuals.

Protein deamidation to produce processable ingredients and engineered colloids for emerging food applications

With the ever-increasing demands for functional and sustainable foods from the general public, there is currently a paradigm shift in the food industry toward the production of novel protein-based diet. Food scientists are therefore motivated to search for natural protein sources and innovative technologies to modify their chemical structure for desirable functionality and thus utilization. Deamidation is a viable, efficient, and attractive approach for modifying proteins owing to its ease of operating, specificity, and cost-effective processes. Over the past three decades, the knowledge of protein deamidation for food applications has evolved drastically, including the development of novel approaches for deamidation, such as protein-glutaminase and ion exchange resin, and their practices in new protein substrate. Thanks to deamidation, enhanced functionalities of food proteins from cereals, legumes, milk, oil seeds and others, and thereby their processabilities as food ingredients have been achieved. Moreover, deamidated proteins have been used to fabricate engineered food colloids, including self-assembled protein particles, protein-metallic complexes, and protein-carbohydrate complexes, which have demonstrated tailored physicochemical properties to modulate oral perception, improve gastrointestinal digestion and bioavailability, and protect and/or deliver bioactive nutrients. Novel bioactivity, altered digestibility, and varied allergenicity of deamidated proteins are increasingly recognized. Therefore, deamidated proteins with novel techno-functional and biological properties hold both promise and challenges for future food applications, and a comprehensive review on this area is critically needed to update our knowledge and provide a better understanding on the protein deamidation and its emerging applications.

l-Arabinose Attenuates Gliadin-Induced Food Allergy via Regulation of Th1/Th2 Balance and Upregulation of Regulatory T Cells in Mice

Gliadins are the main cause of wheat allergies, and the prevalence of gliadin allergy has increased in many countries. l-Arabinose, a kind of plant-specific five-carbon aldose, possesses beneficial effects on food allergy to gliadins. This study investigated the antiallergic activities and underlying mechanisms of l-arabinose in a wheat gliadin-sensitized mouse model. BALB/c mice were sensitized to gliadin by intraperitoneal injections with gliadin followed by being given a gliadin challenge. l-arabinose-treated mice exhibited a marked reduction in the productions of total immunoglobulin E (IgE), gliadin-specific IgE, gliadin-specific IgG1, and histamine, with an increase in IgG2a level as compared with gliadin-sensitized mice. Beside that, a significant decrease in Th2-related cytokine level, IL-4, and an increase in Th1-related cytokine level, IFN-γ, in the serum and splenocytes were observed after treatment with l-arabinose. l-Arabinose treatment also improved the imbalance of Th1/Th2 immune response on the basis of the expression levels of related cytokines and key transcription factors in the small intestine and spleen of sensitized mice. In addition, gliadin-induced intestinal barrier impairment was blocked by l-arabinose treatment via regulation of TJ proteins and suppression of p38 MAPK and p65 NF-κB inflammation signaling pathways. Notably, the results confirmed that l-arabinose treatment increased CD4⁺ Foxp3⁺ T cell populations and Treg-related factors associated with increased expression of IL-2 and activation of STAT5 in gliadin-sensitized mice. In conclusion, l-arabinose attenuated the gliadin-induced allergic symptoms via maintenance of Th1/Th2 immune balance and regulation of Treg cells in a gliadin-induced mouse model, suggesting l-arabinose could be used as a promising agent to alleviate gliadin allergy.

Allergenicity of Fermented Foods: Emphasis on Seeds Protein-Based Products

Food allergy is an IgE-mediated abnormal response to otherwise harmless food proteins, affecting between 5% and 10% of the world preschool children population and 1% to 5% adults. Several physical, chemical, and biotechnological approaches have been used to reduce the allergenicity of food allergens. Fermentation processes that contribute to technological and desirable changes in taste, flavor, digestibility, and texture of food products constitute one of these approaches. Lactic acid bacteria (LAB), used as starter cultures in dairy products, are a subject of increasing interest in fermentation of plant proteins. However, the studies designed to assess the impact of LAB on reduction of allergenicity of seed proteins are at an early stage. This review presents the current knowledge on food fermentation, with a focus on seed proteins that are increasingly used as ingredients, and its impacts on food potential allergenicity.

Allergenicity of Deamidated and/or Peptide-Bond-Hydrolyzed Wheat Gliadin by Transdermal Administration

Hydrochloric acid (HCl)-treated wheat protein (HWP) is widely used in various products, including foods, cosmetics and shampoos. Recently, immediate hypersensitivity towards facial soap containing HWP has been reported. HCl treatment of protein causes hydrolysis not only of main-chain amide bonds (peptide-bond hydrolysis) but also of side-chain ones (deamidation). We have already reported that gliadin, the main allergen in wheat, reduces allergenicity and increases digestibility by deamidation, indicating that deamidation and peptide-bond hydrolysis are effective to reduce the allergenicity of wheat protein. However, transdermally administered HWP is assumed to induce sensitization to orally administered wheat protein even in those who have been taking wheat products daily before sensitization. The present study was conducted to examine which structural change is responsible for the induction of cutaneous sensitization by comparing the allergenicity of deamidated and/or peptide-bond-hydrolyzed wheat gliadin. Because we have developed a deamidation method without causing peptide-bond hydrolysis, only deamidated wheat gliadin is available. Therefore, after deamidated-only, hydrolyzed-only, and deamidated and hydrolyzed gliadins were transdermally administered to mice for several weeks, the corresponding gliadin was intraperitoneally administered and allergenicity was evaluated. Transdermal administration of deamidated and hydrolyzed gliadin induced severe allergic reaction, while that of deamidated-only and hydrolyzed-only gliadin showed almost no allergic response. This result indicates that both deamidation and peptide-bond hydrolysis are necessary to increase the allergenic potency of transdermally administered wheat gliadin.