Bifidobacteria: early allies against allergic risk?
Certain intestinal bifidobacteria, supported in particular by breastfeeding, seem to reduce an infant’s future allergic risk by modulating IgE production.
Lay public section
Find here your dedicated section
Sources
This article is based on scientific information
About this article
Vaginal birth, presence of siblings, pets, living in rural settings : all early exposures that shape immune system development. Everything appears to be decided very early: the presence in infants’ blood of IgE specific to food sensitivity is an early indicator of impaired immune tolerance and future development of allergic diseases. Could gut microbiota play a key role?
16% Food allergen sensitization affects up to 16% of all infants in low- and high-income countries. ¹
Infant-type ALDH+ Bifidobacterium strains
Researchers examined changes in the gut flora of 56 full-term Swedish infants from the ALADDIN cohort 1 followed until age 5. While they were breastfed, their microbiota were dominated largely by Bifidobacterium species carrying the aromatic lactate dehydrogenase (ALDH) gene, including B. bifidum and B. longum, as well as B. infantis and B. breve. The ALDH enzyme catalyzes the final step in converting aromatic amino acids into aromatic lactates (including 4-hydroxyphenyl lactate, or 4-OH-PLA). These aromatic lactates modulate host immunity, although it remains unknown whether they regulate IgE.
x14 Vaginal delivery was associated with a 14-fold higher odds of maternal strain colonization than caesarean section. ¹
A link between bifidobacteria and IgE
This leads to a question from the team: is this early abundance of ALDH+ bifidobacteria associated with allergic sensitization and circulating IgE? Data from 146 children in the same cohort show that ALDH+ bifidobacteria are more abundant in children without food allergen-specific IgE. Conversely, ALDH- bifidobacteria are more abundant in children with such IgE. This association is confirmed in the German PAPS cohort 2.
The levels of aromatic lactates produced by intestinal ALDH+ bifidobacteria during the breastfeeding phase are therefore associated inversely with circulating allergen-specific IgE levels in early childhood.And also with atopic dermatitis at age 2.
½ At preschool age, up to half of the children with circulating IgE against common food allergens in infancy are reported to develop food allergy. ¹
Protective effect of a bifidobacterial metabolite
The microbial metabolite 4-OH-PLA, which specifically inhibits IgE production (without affecting IgG), could explain 40% of the inverse association between the presence of ALDH+ bifidobacteria and circulating IgE levels.
This protective association seems limited to an early immune window (before 5 months of age), when 4-OH-PLA is most abundant in the infant intestine. As solid foods are introduced, its levels drop sharply.
Therefore, an early interaction among gut microbiota, bacterial metabolites and immunity seems to influence allergic sensitivity, reinforcing the importance of the first 1,000 days. In this regard, vaginal delivery, the presence of siblings, and exclusive breastfeeding were each associated with higher 4-OH-PLA levels in stools at 2 months of age, while early introduction of infant formula reduced them. This is yet another reason to support breastfeeding when possible.
