The Sensitising Capacity of Intact β-Lactoglobulin Is Reduced by Co-Administration with Digested β-Lactoglobulin

Abstract

Background: It is generally believed that protein hydrolysis in the gastrointestinal tract decreases the allergenicity of food allergens. However, it remains unknown if specific properties of digestion products determine whether a sensitisation or tolerogenic immune response will develop. We sought to examine the sensitising capacity of the cow’s milk allergen β-lactoglobulin (BLG) and digestion products thereof in a Brown Norway (BN) rat model. Methods: Intact BLG was digested in an in vitro model simulating the gastro-duodenal digestion process and subsequently fractionated by gel permeation chromatography. BN rats were dosed with either PBS, 200 µg of intact BLG, 30 µg of intact BLG, 200 µg of partially digested BLG, 200 µg of digested BLG, or with 200 µg of a fraction of large complexes or a fraction of small complexes. Sera from BN rats were analysed for specific antibodies and avidity was measured. Results: BLG partly resisted the digestion process. However, the BLG molecules that did not survive the digestion process were rapidly broken down to peptides of sizes less than M_r 4,500. Specific antibody responses revealed that both 200 and 30 µg of intact BLG had immunogenic as well as sensitising capacity, while digested BLG could not induce any specific antibodies. Most importantly, while intact BLG showed a significant sensitising capacity when administered alone, this sensitising capacity was significantly reduced when co-administered with digested BLG. Conclusions: Co-immunisation of intact BLG with digested BLG reduces the sensitising capacity of intact BLG, which could result from tolerogenic mechanisms induced by the digestion products.

Preclinical Brown Norway Rat Models for the Assessment of Infant Formulas in the Prevention and Treatment of Cow’s Milk Allergy

“…Interestingly, we previously found that the sensitising capacity of intact BLG was reduced by co-administration with digested BLG [21], yet the desensitising capacity of such a mixture remains unknown. Previous studies have reported that pepsin-hydrolysed cashew nut protein extract [22] and aminopeptidase-hydrolysed egg white [23] have a desensitising capacity, but the presence of intact protein in these preparations is unclear.…”

The impact of structural integrity and route of administration on the antibody specificity against three cow's milk allergens ‐ a study in Brown Norway rats

“…The amount of specific IgE antibodies only account for a small fraction of the total sum of specific antibodies, for which reason an antibody-capture ELISA is a far more sensitive choice than an indirect ELISA for most allergens. The ELISAs were performed with native or denatured digoxigenin-coupled BLG, native or denatured digoxigenin-coupled ALA and digoxigenin-coupled β -casein essentially as described in Bøgh et al [21]. ELISAs were not performed with denatured digoxigenin-coupled β -casein due to shortness of the β -casein source.…”

Do lipids influence the allergic sensitization process?

“…Once the tightly packed β-lactoglobulin is disrupted, hydrophobic residues become exposed and readily available for insertion into the lipid bilayer 76 . The importance of the intact structure and functionality for the immunogenic and sensitizing capacity of β-lactoglobulin was indicated by a recent study 77 . Only the intact, but not the digested, β-lactoglobulin was able to induce IgG and IgE antibody responses in a Brown Norway rat model.…”