Assessment of the Sensitizing Potential of Proteins in BALB/c Mice: Comparison of Three Protocols of Intraperitoneal Sensitization

Characterization of the potential allergenicity of enzymatically hydrolyzed casein in Balb/c mouse model

Bovine casein is a major allergen present in cow milk to induce anaphylaxis. In this study, the potential allergenicity of enzymatically hydrolyzed casein (HC) was evaluated based on in vitro and in vivo. The results showed that Alcalase and Protamex treatment (AT, PT) reduced the potential allergenicity of CN, with the greatest reductions of 68.25% and 50.75%, respectively. In addition, in vivo results showed that HC effectively alleviated allergic response symptoms of Balb/c mice; a significant tendency toward decreased serum IgG1 and mast cell tryptase levels was observed, accompanied by a decrease of Th2-associated IL-4, IL-5, and IL-13 and an increase of IFN-γ levels in spleen. Moreover, the inflammation of the lung, jejunum, and ileum was remarkably ameliorated. The findings indicated that HC induced a shift toward Th1 response and maintained the Th1/Th2 immune balance. Importantly, our results provide the basis for the production of hypoallergenic dairy products.

A Food Matrix Triggers a Similar Allergic Immune Response in BALB/c Mice Sensitized with Native, Denatured, and Digested Ovalbumin

The search for an animal model to evaluate the allergenic potential of processed food products is still ongoing. Both the sensitization to ovalbumin (OVA) in different structural states and the allergic response triggered after intragastric or food challenges were assessed. BALB/c mice were sensitized intraperitoneally to OVA (50 µg) in different structural states (native OVA, N-OVA; denatured OVA, D-OVA; formaldehyde- and lysine-treated OVA, FK-OVA; denatured OVA-FK, OVA-DFK; peptides from pepsin digestion, Pep-OVA). Anti-OVA-specific IgE responses were evaluated using ELISA. Anaphylactic signs and mMCP-1 serum levels were evaluated after intragastric (2.0 mg/OVA) and food (0.41 mg/OVA) challenges. IgE reactivities to N-OVA and D-OVA were similar among groups (p > 0.05). After the challenges, all OVA-sensitized mice developed mild to severe anaphylactic signs (p < 0.05 vs. control). Mice sensitized to N-OVA and D-OVA had the highest mMCP-1 serum levels after challenges (p < 0.05 vs. control). Allergic responses were similar despite the different OVA doses used for the challenges. The N-OVA-sensitized murine model of egg allergy proposed in the present study holds the potential for evaluating the impact of food matrix composition and processing on the threshold of egg-allergic responses.

A comprehensive overview of emerging processing techniques and detection methods for seafood allergens

Seafood is rich in nutrients and plays a significant role in human health. However, seafood allergy is a worldwide health issue by inducing adverse reactions ranging from mild to life-threatening in seafood-allergic individuals. Seafood consists of fish and shellfish, with the major allergens such as parvalbumin and tropomyosin, respectively. In the food industry, effective processing techniques are applied to seafood allergens to lower the allergenicity of seafood products. Also, sensitive and rapid allergen-detection methods are developed to identify and assess allergenic ingredients at varying times. This review paper provides an overview of recent advances in processing techniques (thermal, nonthermal, combined [hybrid] treatments) and main allergen-detection methods for seafood products. The article starts with the seafood consumption and classification, proceeding with the prevalence and symptoms of seafood allergy, followed by a description of biochemical characteristics of the major seafood allergens. As the topic is multidisciplinary in scope, it is intended to provide information for further research essential for food security and safety.

Assessment of the Route of Exposure to Ovalbumin and Cow's Milk Proteins on the Induction of IgE Responses in BALB/c Mice

BALB/c mice can be orally sensitized to food proteins under acid suppressive medication, mimicking human exposure and triggering a human-like allergic immune response. However, the reproducibility of such an oral food allergy model remains questionable. Our aim was to evaluate the IgE responses triggered against ovalbumin (OVA) and cow’s milk proteins (CMP) after intragastric (IG), either under gastric-acid suppression or not, or intraperitoneal (IP) sensitization in BALB/c mice. OVA (0.2 mg) and different concentrations of CMP were administered with/without the antacid sucralfate by the IG route. For IP sensitization, OVA or CMP (0.5 mg) were administered. ELISA was used to evaluate IgE responses. The IP sensitization protocols triggered more robust and consistent anti-OVA or anti-CMP IgE responses than the intragastric ones (with/without sucralfate) (p < 0.05). 2.7% (1/36), and 5.5% (3/54) of the mice that underwent the sucralfate-assisted IG protocol triggered IgE responses against OVA or CMP, respectively. All the mice were administered OVA or CMP via IP triggered detectable IgE responses. The IP sensitization model is more reliable than the IG one for evaluating the intrinsic sensitizing and/or allergenic potential of food proteins, even if IG immunizations are carried out under gastric-acid suppression.

Two allergens from Scylla paramamosain share common epitopes showed different allergenic potential in Balb/c mice

Filamin C (FLN c) and triosephosphate isomerase (TIM) are novel allergens of crab (Scylla paramamosain) which are sharing common epitopes. This work aimed to assess their contributions to the induction and elicitation of allergenic responses. Balb/c mice were sensitized by intraperitoneal injections and challenged by intragastric gavage with purified proteins. Upon oral challenge, FLN c triggered more severe anaphylactic symptoms, higher levels of specific antibodies and histamine in serum than TIM, while TIM was a more active promotor of early specific antibody production and stimulated stronger Th2-biased responses. Combined with the results of in vitro assays, the data demonstrated that though with common epitopes, the two allergens showed a different allergenicity, TIM favored Th2 polarization in sensitization stage, while FLN c had a better ability to stimulate B cells and is highly immunogenic in oral challenge stage. The findings can help with the better understanding of allergenicity of crab allergens.

Assessment of allergenicity of irradiated dairy products in a Balb/c mice model

The objective of the presentin vivostudy was to analyze the changes in the immune response of the sensitized Ваlb/c mice against milk allergens in lyophilized cow’s milk (LCM) and whey curd (LC) before and after gamma irradiation (10 kGy). The results showed lower levels of IgE in the group treated with irradiated LCM (ICM) compared to the group treated with non-irradiated LCM (NiCM). Hence, it could be suggested that gamma irradiation influenced the epitopes of the major milk proteins and was associated with lower allergenicity of the lyophilized irradiated milk. The gamma irradiation in the whey curd, however, did not significantly change the level of IgE antibodies in IC (treated with irradiated LC) compared to NiC (treated with non-irradiated LC) group.

Influence of heat treatment and egg matrix on the physicochemical and allergenic properties of egg custard

To investigate the influence of heat treatment and egg matrix on egg custard (EC) proteins, 12 different kinds of ECs with different egg/water ratios (1:1, 1:1.5, 1:2, or 1:3, v/v) and different heating temperatures (80, 90, or 100 °C) and times (10, 15, or 20 min) were prepared and evaluated for the digestibility, structure, eliciting capacity and sensitizing capacity using SDS-PAGE, fluorescence spectra, ELISA, and a BALB/c mouse model, respectively. The physicochemical properties of EC proteins were significantly affected by heat treatment and egg matrix, which showed the increased digestibility and partially unfolded structure. The eliciting capacity of EC evaluated by IgE binding to sera from egg-allergic patients was reduced after heat treatment, and the EC made by heating at 100 °C for 20 min with a whole egg/water ratio of 1:2 (v/v) was the weakest. The sensitizing capacity of EC was also reduced in the BALB/c mouse model, which showed the significantly decreased levels of specific IgE, IgG, IgG1 and IgG2a, mMCP-1 and histamine in the mouse sera, as well as cytokine secretions of IL-4, IL-5, and IL-13, compared with the raw egg (RE) group. Results demonstrate that heat treatment and egg matrix significantly reduced the eliciting and sensitizing capacity of EC by changing the tertiary structure and increasing the digestibility of EC proteins. PRACTICAL APPLICATION: Egg custard (EC) is one kind of savory food suitable for all ages, and is also a traditional supplementary food for infants and young children in China. However, limited information is available on the allergenicity of egg custard. In this work, we evaluated how the structure, digestibility, and allergenic potential of egg allergens in EC were altered by the degree of thermal treatment and egg matrix, and elucidated the links between the physicochemical properties and allergenic potential of EC affected by heat treatment and egg matrix. Our results demonstrate that heat treatment and egg matrix significantly reduced the eliciting and sensitizing capacity of EC by changing the tertiary structure and increasing the digestibility of EC proteins.

Milk and Meat Allergens from Bos taurus β-Lactoglobulin, α-Casein, and Bovine Serum Albumin: An In-Vivo Study of the Immune Response in Mice

The mechanism of food allergy may vary. This study aimed to compare the effects of milk, yogurt, or beef meat supplementation on humoral and cellular immune responses in a mice model. Mice were divided into four groups: The "Milk group" was sensitized with a β-lactoglobulin (β-lg)/α-casein (α-CN) mixture and supplemented cow milk; the "Yogurt group" was sensitized with β-lg/α-CN and supplemented yogurt; the "Beef group" was immunized with bovine serum albumin (BSA) and supplemented beef meat; and the "PBS group" received PBS in all procedures. ELISA was used to measure humoral response, including: Total IgE, specific IgG, and IgA. Cellular response was determined by phenotyping lymphocyte from lymphoid tissue and measuring the Th1/Th2 cytokine concentration with flow cytometry. The qPCR method was used for quantification of the fecal microbiota. The results obtained revealed a lower IgE level for the Yogurt group than for the Milk one. In the Yogurt group, the contribution of regulatory T cells to MLN and PP was higher compared to the other groups. We confirmed that diet supplementation with yogurt modulates the immune response to the prime allergen, and changes the activity of serum antibodies to milk proteins and BSA. Based on a specific antibodies level, we cannot exclude the possibility of CMA mice reaction against BSA.

Assessing the Sensitizing and Allergenic Potential of the Albumin and Globulin Fractions from Amaranth (Amaranthus hypochondriacus) Grains before and after an Extrusion Process

Background: The first cases of food allergy to amaranth grain have recently been published. This pseudocereal is considered hypoallergenic, and there is scarce information about the allergenic potential of amaranth proteins, either before or after food processing. Objective: To evaluate, in a mouse model of food allergy, the sensitizing and allergenic potential of extruded and non-extruded albumin and globulin fractions from amaranth grains. Materials and Methods: Amaranth (Amaranthus hypochondriacus) flour was obtained and the albumin and globulin fractions isolated. These protein fractions were also obtained after flour extrusion. An intraperitoneal 28-day protocol was carried out to evaluate the sensitizing and allergenic potential of the proteins. The common and rarely allergenic proteins ovalbumin and potato acidic phosphatase were utilized as reference. Specific IgE and IgG antibodies were evaluated for all the proteins tested. Mast cell protease-1 (mMCP-1) responses were evaluated in serum samples collected after intragastric challenges with the proteins of interest. All serological evaluations were carried out using ELISA. Results: Mice were sensitized to the non-extruded albumin fraction from amaranth grains and to ovalbumin (p = 0.0045). The extrusion process of amaranth proteins abrogated the IgE responses triggered under non-extruded conditions (p = 0.0147). mMCP-1 responses were significantly detected in the group of mice sensitized to ovalbumin (p = 0.0138), but not in others. Conclusions: The non-extruded albumin fraction from amaranth has the potential to sensitize BALB/c mice, but this sensitizing potential fails to induce detectable serum levels of the mast cell degranulation marker mMCP-1 after intragastric challenges. Furthermore, the extrusion process abolished the sensitization potential of the amaranth albumins.

Effects of thermal processing on digestion stability and immunoreactivity of the Litopenaeus vannamei matrix

Many types of shellfish, including shrimp, are sometimes cooked before ingestion.