Understanding Apple Allergies: How Polyphenols Interact with Allergenic Proteins

Jenn Hoskins
12th July, 2024

Understanding Apple Allergies: How Polyphenols Interact with Allergenic Proteins

Image Source: Natural Science News, 2024

Key Findings

  • The study from the University of Hamburg found that only a small fraction (6-15%) of the allergen Mal d 1 is released during oral digestion
  • Oligomeric polyphenols and browning products cause Mal d 1 to aggregate, potentially reducing its allergenicity
  • The interaction between polyphenols and Mal d 1 could explain why some apple cultivars are better tolerated by individuals with birch pollen allergies
Apple allergies are a significant concern for many individuals, particularly those with birch pollen allergies. This is due to a phenomenon known as cross-reactivity, where proteins in birch pollen and apples share similar structures, leading to allergic reactions[2]. A recent study conducted by researchers at the University of Hamburg has provided new insights into why certain apple cultivars might be better tolerated by individuals with these allergies[1]. The study focused on the interaction between phenolic compounds, which are abundant in some apple varieties, and the allergen Mal d 1. Mal d 1 is the primary protein responsible for allergic reactions in apple-allergic individuals and is structurally similar to the major allergen found in birch pollen, Bet v 1[2]. This structural similarity often leads to oral allergy syndrome (OAS), where individuals experience allergic reactions localized in the mouth and throat after consuming apples[3]. The researchers investigated how Mal d 1 is released during the oral digestion phase and found that only a small fraction (6-15%) of the total Mal d 1 present in apples is released. This limited release could be a factor in why some apple cultivars are better tolerated than others. The study employed various analytical methods, including isothermal titration calorimetry, 1H-15N-HSQC NMR, and untargeted mass spectrometry, to explore the interactions between Mal d 1 and polyphenols, which are compounds known for their antioxidant properties. Interestingly, the study revealed that monomeric polyphenols (single molecule forms) exhibited only limited noncovalent interactions with Mal d 1. In contrast, oligomeric polyphenols (larger, multi-molecule forms) and browning products caused Mal d 1 to aggregate. This aggregation could potentially reduce the allergenicity of Mal d 1, as aggregated proteins are less likely to trigger an allergic response. Additionally, while covalent modifications of Mal d 1 were not detectable in apple samples, a specific chemical reaction involving epicatechin (a type of polyphenol) and cysteine 107 in Mal d 1 was observed. This reaction, known as Michael addition, could further alter the allergenic potential of Mal d 1. These findings build on earlier research that highlighted the variability in allergenicity among different apple cultivars. For instance, a study demonstrated that apple varieties like Golden Delicious and Santana differ significantly in their allergenic potential, as confirmed by skin prick tests and double-blind, placebo-controlled food challenges (DBPCFC)[4]. The current study from the University of Hamburg provides a molecular basis for these observations, suggesting that polyphenol content and interactions with Mal d 1 play a crucial role in determining the allergenicity of different apple cultivars. The implications of this research are significant for individuals with apple allergies and those involved in apple cultivation and storage. By selecting apple cultivars with higher polyphenol content and optimizing storage conditions, it may be possible to reduce the allergenicity of apples and improve tolerance for allergic individuals[4]. Furthermore, understanding the molecular interactions between allergens and polyphenols could pave the way for developing new strategies to manage and treat food allergies more effectively. In summary, the study conducted by the University of Hamburg sheds light on the complex interactions between phenolic compounds and the allergen Mal d 1 in apples. By revealing how these interactions can influence the release and aggregation of Mal d 1 during digestion, the research provides valuable insights into why some apple cultivars are better tolerated by individuals with birch pollen allergies. This knowledge could inform future efforts to breed and store apples in ways that minimize their allergenic potential, ultimately benefiting those affected by apple allergies.

FruitsHealthBiochem

References

Main Study

1) Multianalytical Approach to Understand Polyphenol-Mal d 1 Interactions to Predict Their Impact on the Allergenic Potential of Apples.

Published 11th July, 2024

https://doi.org/10.1021/acs.jafc.4c01555

Related Studies

2) Structure of the Major Apple Allergen Mal d 1.

https://doi.org/10.1021/acs.jafc.6b05752

4) In vivo assessment with prick-to-prick testing and double-blind, placebo-controlled food challenge of allergenicity of apple cultivars.

Journal: The Journal of allergy and clinical immunology, Issue: Vol 116, Issue 5, Nov 2005


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