To understand the role of early microbial colonisation in the prevention of food allergies in children through supplementation with breast milk oligosaccharides

At present, one third of the world’s population is affected by one or more allergies, and their prevalence continues to rise (Sanchez-Borges et al., World Allergy Organization Journal, 2018). Food allergies result from a disproportionate reaction by the immune system to a food that is normally harmless to the body, combined with an imbalance in the gut microbiota and the intestinal epithelial barriers. During the first 1,000 days of life (from conception to the age of 2), the diet of pregnant women can influence the development and maturation of these biological systems in the child, representing a window of opportunity to intervene and regulate the development of allergies. The sugars in breast milk, in particular 2’-fucosyllactose (2’-FL), possess anti-inflammatory properties, promote the colonisation of gut bacteria beneficial to health and strengthen the gut barrier (Rousseaux et al., Front Immunol. 2021). We have demonstrated that maternal supplementation with 2’-FL during pregnancy prevents the onset of food allergy in offspring (Rousseaux et al., Allergy 2024). This protection was associated with the establishment of an in utero immune imprint, which persists in the offspring, as well as with changes in the microbiota in both the mother and her offspring (Brosseau et al., Gut Microbes 2025).

In order to understand the protective role of the tolerance response induced in the offspring of mothers who had received supplementation, we prevented the vertical transfer of the maternal microbiota at birth. We demonstrated that offspring exposed to 2’-FL were no longer protected against the symptoms of food allergy, despite the presence of an in utero immune imprint. The aim of this project is to determine whether the specific microbiota imprint alone is sufficient to prevent food allergy, without the need for an in utero immune imprint. To this end, we will transfer the 2’-FL maternal microbiota to newborns born to mothers who have not been supplemented with 2’-FL, in order to mimic the transfer of the 2’-FL microbiota at birth without inducing in utero immune imprinting. This study will be the first to identify the mechanisms by which a nutritional strategy can prevent food allergy. This preclinical project will provide essential proof of concept prior to clinical development and may pave the way for a new nutritional strategy for the primary prevention of allergies.

The project is coordinated by Marie Bodinier, head of the Allergy team, and is being carried out as part of Marine Le Romancer’s PhD thesis. The model used, as well as the analysis of allergy symptoms and markers, the characterisation of the immune system and the statistical analyses, will be carried out within the Allergy team.

Synopsis

• Project start date : janvier 2027 (18 mois)
• Coordination : Marie BODINIER (équipe Allergie)
• Partners : Host-microbe interactions and pathophysiology, Pasteur Institute, France; Institut MICALIS, INRAE, France; Equipes Allergie, BIA.
• Funding : Programme de partenariat de l'Institut Biostime pour la recherche en nutrition et en soins.

Contact :  Marie BODINIER, marie.bodinier@inrae.fr