# Poster Session I - A31 ORAL MICROBIAL DEGRADATION OF FOOD ALLERGENS: IMPLICATIONS FOR PEANUT AND COW’S MILK ALLERGY

## TL;DR

This study explores how oral bacteria can break down food allergens like peanut and cow's milk proteins, potentially reducing their ability to trigger allergic reactions.

## Contribution

The study identifies specific bacteria that degrade major food allergens and demonstrates their potential to reduce allergen immunogenicity in a mouse model.

## Key findings

- Bacteria from human saliva, including Rothia and Lactobacillus, degrade peanut and dairy allergens like Ara h 1, Ara h 2, Bos d 5, and Bos d 11.
- Degradation of peanut allergens by Rothia and Clostridium strains reduced mast cell degranulation in a mouse model of food allergy.
- Microbial degradation of allergens may explain variability in peanut allergy thresholds among patients.

## Abstract

Food allergies affect 5-10% of Canadians, often leading to severe immune reactions and anaphylaxis to specific food proteins. Despite their prevalence, research on preventive treatments remains limited, and life-threatening anaphylaxis from accidental exposure remains a significant concern. Common allergens include peanut (PN) and cow’s milk (dairy) proteins. PN allergy is typically characterized by Th2-skewed, IgE-mediated immune responses to major allergens such as Ara h 1 and Ara h 2, while cow’s milk allergy often involves IgE reactivity to Bos d 5 and Bos d 11. These allergens are highly resistant to human enzyme degradation, contributing to their immunogenic properties. However, the orogastrointestinal microbiota, comprising trillions of bacteria, can degrade proteins that human enzymes cannot, suggesting that bacterial digestion may aid in allergen elimination and attenuation of IgE-mediated immune responses.

Aim 1: To identify bacteria capable of breaking down PN and dairy allergens.

Aim 2: To test PN and dairy immunogenicity after bacterial digestion.

Saliva samples collected from healthy volunteers were incubated on different agar media supplemented with PN or dairy proteins. Bacteria with the capacity to degrade these proteins macroscopically were selected and further tested to degrade immunodominant allergens Ara h 1, Ara h 2, Bos d 5 and Bos d 11 by ELISA (Inbio) and SDS-PAGE. Additionally, a collection of Lactobacillus was screened for their capacity to degrade the same allergens. Bacteria with the capacity to degrade PN were tested in a new mouse model of PN sensitization and challenge. Briefly, mice were sensitized intraperitoneally to PN and then challenged to PN previously digested with the bacteria of interest, or native PN.

A total of 81 bacteria belonging to Staphylococcus, Rothia, Neisseria and other minor genera were isolated from human saliva with the capacity to degrade PN/dairy allergens. Lactobacillus also contributed to peanut and dairy allergen degradation. Rothia, Lactobacillus, Clostridium and specific species of Staphylococcus degrade the immunodominant allergens Ara h 1 and 2, and Bos d 5 and Bos d 11. Furthermore, PN degradation by Rothia and Clostridium strains reduced mast cell degranulation compared to intact PN in a preclinical mouse model of IgE-mediated food allergy.

Oral bacteria efficiently degrade food allergens thereby affecting their immunogenicity. This microbial activity may help explain the variability in peanut thresholds observed among allergic patients. Bacteria such as Lactobacillus and Rothia show potential for increasing allergen threshold or mitigating allergen cross-contamination in the food industry.

NRCCanadian Allergy, Asthma, and Immunology Foundation (CAAIF)