IgE-Mediated Rat Mast Cell Triggering with Tryptic and Synthetic Peptides of Bovine β-Lactoglobulin

Influence of Complexation with β- and γ-Cyclodextrin on Bioactivity of Whey and Colostrum Peptides

Dairy protein hydrolysates possess a broad spectrum of bioactivity and hypoallergenic properties, as well as pronounced bitter taste. The bitterness is reduced by complexing the proteolysis products with cyclodextrins (CDs), and it is also important to study the bioactivity of the peptides in inclusion complexes. Hydrolysates of whey and colostrum proteins with extensive hydrolysis degree and their complexes with β/γ-CD were obtained in the present study, and comprehensive comparative analysis of the experimental samples was performed. The interaction of CD with peptides was confirmed via different methods. Bioactivity of the initial hydrolysates and their complexes were evaluated. Antioxidant activity (AOA) was determined by fluorescence reduction of fluorescein in the Fenton system. Antigenic properties were studied by competitive enzyme immunoassay. Antimutagenic effect was estimated in the Ames test. According to the experimental data, a 2.17/2.78-fold and 1.45/2.14-fold increase in the AOA was found in the β/γ-CD interaction with whey and colostrum hydrolysates, respectively. A 5.6/5.3-fold decrease in the antigenicity of whey peptides in complex with β/γ-CD was detected, while the antimutagenic effect in the host-guest systems was comparable to the initial hydrolysates. Thus, bioactive CD complexes with dairy peptides were obtained. Complexes are applicable as a component of specialized foods (sports, diet).

Development of a Two-Step Hydrolysis Hypoallergenic Cow's Milk Formula and Evaluation of Residue Allergenicity by Peptidomics and Immunoreactivity Analysis

Cow's milk allergy (CMA) is an abnormal immune response that severely affects the nutritional supplementation of allergic infants. Currently, only a limited number of hypoallergenic formulas are available on the market, and these are only categorized according to their degree of hydrolysis, which still poses an allergy risk and cannot be consumed by CMA patients, especially infants. To address this issue, we developed a two-step hydrolysis hypoallergenic formula targeting destruction of allergen epitope from whey protein. Then, a comprehensive evaluation system was constructed, including peptidomics analysis, in vivo and in vitro allergenicity assessments, revealing allergic changes in the product from the epitope structure level to the immunological level. The results showed that 97.14% of hydrolyzed peptides from α-lactalbumin and β-lactoglobulin did not contain allergenic epitopes after treatment with trypsin and flavourzyme. In vitro and in vivo allergenicity assessment results confirmed that the two-step hydrolysis method effectively reduced the allergenicity of whey protein. Compared with the common milk powder, the hypoallergenic formula induced lower levels of basophil degranulation and relieved the body's anaphylactic symptoms caused by cow milk. This study provides a promising solution to the limited hypoallergenic formula problem and may benefit allergic infants who require nutritional supplements.

Allergenicity reduction of cow milk treated by alkaline protease combined with Lactobacillus Plantarum and Lactobacillus helveticus based on epitopes

This paper has investigated the residual allergenicity of cow's milk treated by enzymatic hydrolysis combined with Lactobacillus fermentation (Lb. Plantarum and Lb. helveticus). The treated products were comprehensively evaluated by SDS-PAGE, RP-HPLC, ELISA, and Caco-2 models. And the allergenic changes of residual allergenic peptides were explored by DC-T co-culture. The results showed that alkaline protease was the most suitable protease that targeted to destroy epitopes of milk major allergen than trypsin, pepsin, and papain by prediction. And the residual epitopes were reduced to four which was treated by alkaline protease combined with Lb. helveticus. The transport absorption capacity of treated products was almost twice than milk. Meanwhile, the seven residual allergenic peptides were obtained from treated products. Among them, αs₁-casein (AA84-90) can be used as an immune tolerance peptide for further study. Lb. helveticus combined with alkaline protease treatment may be considered promising strategy of protect from cow's milk allergy.

Identification of peptides sequence and conformation contributed to potential allergenicity of main allergens in yogurts

Yogurts provide a good source of nutrition and may induce tolerance in people with cow's milk allergy (CMA). This study aimed to investigate the IgE-binding capacity of main allergens in the different yogurts which provide a reference for people with a high risk of CMA, and analyze the epitopes of major allergen peptides in yogurt. We assessed the degradation and the allergenic properties of major allergens in six commercial yogurts and fresh milk. The degradation of major allergens was analyzed by SDS-PAGE and RP-HPLC. Western blot and ELISA experiments detected allergenic characteristics by using specific sera. The results showed that β-lactoglobulin (Bos d 5) and α-lactalbumin (Bos d 4) were obviously degraded in yogurts but caseins were still present in abundance, which indicated that the proteases in yogurts were specific to whey proteins. IgE and IgG binding ability of major allergens were obviously reduced in yogurts, especially GuMi yogurt. In addition, 17 peptides of major allergens in GuMi yogurt were identified by LC-MS/MS and most of them were located in the interior of the spatial structure of proteins. Among them, 8 peptides had specific biological functions for health benefits, such as antibacterial, antioxidant, and ACE-inhibitory. We also found that 6 and 14 IgE epitopes of Bos d 5 and caseins were destroyed in GuMi yogurt, which could lead to the reduction of IgE-binding capacity. Meanwhile, peptides [Bos d 5 (AA15-40), Bos d 9 (AA120-151, AA125-151)] also preserved T cell epitopes, which might also induce the development of oral tolerance. Therefore, this study suggested that the sequence and conformation of peptides in yogurts contributed to hypoallergenicity.

Identification of conformational antigenic epitopes and dominant amino acids of buffalo β-lactoglobulin

Major allergen β-lactoglobulin exists in many mammalian types of milk except human breast. Buffalo milk also contains this major allergen but the detailed information on its epitopes is not available. The aim of this work was to map and characterize its conformational antigenic epitopes. Sixty mimotopes of buffalo β-lactoglobulin were produced by biopanning of phage display peptide library and then 2 mimotopes, specific for sera from rabbit 1 and 2, respectively, were predicted to be conformational epitope candidates by the use of DNAStar and web tool of MIMOX. On the basis of bioinformation analysis, 5 conserved amino acid residues PL-ENK were identified in 2 conformational epitope sequences and 7 conformational epitopes were derived from 2 mimotopes by molecular modeling. The result showed that these conformational epitopes were located in the 2 regions on buffalo β-lactoglobulin and composed of 5 hydrophilic and 2 hydrophobic amino acids.

Hydrolysis under high hydrostatic pressure as a means to reduce the binding of beta-lactoglobulin to immunoglobulin E from human sera

Cows' milk allergy is the most frequent food allergy in children, and beta-lactoglobulin (beta-Lg) is a major allergen. Milk-based hypoallergenic ingredients are manufactured by enzymatic hydrolysis, a process that could be improved by the application of high-pressure treatments. This study showed that the treatment of beta-Lg dissolved in buffer with chymotrypsin and trypsin under high pressure for relatively short times accelerated proteolysis by leading to a rapid removal of the intact protein. The rapid proteolysis of the beta-Lg substrate under pressure led to the production, in 20 min, of hydrolysates with lower immunoglobulin (Ig) G binding than those produced in 8 h (chymotrypsin) or 48 h (trypsin) at atmospheric pressure. However, those hydrolysates retained some residual IgE-binding properties that could be traced to the preferential release, during the initial stages of proteolysis, of peptides containing IgE epitopes, such as (Val-41-Lys-60), (Leu-149-Ile-162), and (Ser-21-Arg-40). The formation of these fragments was favored when proteolysis was conducted under high pressure due to the preferential hydrolysis of Arg-40 and Arg-148 by trypsin, and Tyr-42 and Leu-149 by chymotrypsin, all located at the dimer interface of beta-Lg or very close to it. Although our results do not support that trypsin and chymotrypsin under high pressure selectively address the allergenic regions of beta-Lg, it is possible to select the conditions that quickly produce hydrolysates with reduced potential allergenicity that could be used in hypoallergenic foods.