Thioredoxin treatment increases digestibility and lowers allergenicity of milk

• Published in: Journal of allergy and clinical immunology 1999-04, Vol.103 (4), p.690-697
• Main Authors: del Val, Gregorio, Yee, Boihon C., Lozano, Rosa M., Buchanan, Bob B., Ermel, Richard W., Lee, Yung-Moo, Frick, Oscar L.
• Format: Article
• Language: English
• Subjects: Allergic diseases; Animals; b-lactoglobulin; Biological and medical sciences; Cattle; Digestion; Digestive System - pathology; Disease Models, Animal; dog model; Dogs; Humans; Immunopathology; Lactoglobulins - chemistry; Lactoglobulins - immunology; Lactoglobulins - metabolism; Medical sciences; Milk - adverse effects; Milk - immunology; Milk - metabolism; milk allergy; milk allergy alleviation; milk allergy mitigation; Milk Hypersensitivity - prevention & control; Models, Molecular; NADP-thioredoxin reductase; Other localizations; Oxidation-Reduction; Pepsin A - metabolism; Skin Tests; Thioredoxin; thioredoxin and allergy alleviation/mitigation; Thioredoxin-Disulfide Reductase - metabolism; Thioredoxins - metabolism; β-lactoglobulin allergenicity; β-lactoglobulin digestibility
• ISSN: 0091-6749; 1097-6825
• DOI: 10.1016/S0091-6749(99)70244-7

Background: By resisting digestion in the stomach, the major bovine milk allergen, β-lactoglobulin, is believed to act as a transporter of vitamin A and retinol to the intestines. β-Lactoglobulin has 2 intramolecular disulfide bonds that may be responsible for its allergic effects. Objective: This study was carried out to assess the importance of disulfide bonds to the allergenicity and digestibility of β-lactoglobulin. Methods: β-Lactoglobulin was subjected to reduction by the ubiquitous protein thioredoxin, which was itself reduced by the reduced form of nicotinamide adenine dinucleotide phosphate by means of nicotinamide adenine dinucleotide phosphate-thioredoxin reductase. Digestibility was measured with a simulated gastric fluid; results were analyzed by SDS-PAGE. Allergenicity was assessed with an inbred colony of high IgE–producing dogs sensitized to milk. Results: As found for other proteins with intramolecular disulfide bonds, β-lactoglobulin was reduced specifically by the thioredoxin system. After reduction of one or both of its disulfide bonds, β-lactoglobulin became strikingly sensitive to pepsin and lost allergenicity as determined by skin test responses and gastrointestinal symptoms in the dog model. Conclusion: The results provide new evidence that thioredoxin can be applied to enhance digestibility and lower allergenicity of food proteins. (J Allergy Clin Immunol 1999;103:690-7.)