A free amino acid-based diet partially prevents symptoms of cow's milk allergy in mice after oral sensitization with whey.

Background: Amino acid-based formulas (AAFs) are used for the dietary management of cow's milk allergy (CMA). Whether AAFs have the potential to prevent the development and/or symptoms of CMA is not known.
Objective: The present study evaluated the preventive effects of an amino acid (AA)-based diet on allergic sensitization and symptoms of CMA in mice and aimed to provide insight into the underlying mechanism.
Methods: C3H/HeOuJ mice were sensitized with whey protein or with phosphate-buffered saline as sham-sensitized control. Starting 2 weeks before sensitization, mice were fed with either a protein-based diet or an AA-based diet with an AA composition based on that of the AAF Neocate, a commercially available AAF prescribed for the dietary management of CMA. Upon challenge, allergic symptoms, mast cell degranulation, whey-specific immunoglobulin levels, and FoxP3 ⁺ cell counts in jejunum sections were assessed.
Results: Compared to mice fed with the protein-based diet, AA-fed mice had significantly lower acute allergic skin responses. Moreover, the AA-based diet prevented the whey-induced symptoms of anaphylaxis and drop in body temperature. Whereas the AA-based diet had no effect on the levels of serum IgE and mucosal mast cell protease-1 (mMCP-1), AA-fed mice had significantly lower serum IgG2a levels and tended to have lower IgG1 levels (P = .076). In addition, the AA-based diet prevented the whey-induced decrease in FoxP3 ⁺ cells. In sham-sensitized mice, no differences between the two diets were observed in any of the tested parameters.
Conclusion: This study demonstrates that an AA-based diet can at least partially prevent allergic symptoms of CMA in mice. Differences in FoxP3 ⁺ cell counts and serum levels of IgG2a and IgG1 may suggest enhanced anti-inflammatory and tolerizing capacities in AA-fed mice. This, combined with the absence of effects in sham-sensitized mice indicates that AAFs for the prevention of food allergies may be an interesting concept that warrants further research.
(© 2020 The Authors. Immunity, Inflammation and Disease published by John Wiley & Sons Ltd.)