Low gut Bacteriodes abundance associated with peanut allergy in childhood

Results of an observational study show an association between persistently low level of gut Bacteroides abundance throughout infancy and sensitization to peanuts in full-term infants at the age of 1–3 years, with a further increase in risk of sensitization to peanuts in infants born to Asian mothers.

“Our study is the first to demonstrate an association between persistently low level of gut Bacteroides abundance throughout infancy, mother’s Asian ethnicity, and food sensitization,” said the authors. “Our findings support future development of microbiota-based preventive and therapeutic interventions for food allergy in toddlers.” [Gastroenterology 2021;doi:10.1053/j.gastro.2021.03.016]

“The level of gut Bacteroides, a type of bacteria known to be critical for immune system development, increases with age, with high level of gut Bacteroides abundance indicative of maturation of gut microbiome in children,” said investigator Dr Hein M Tun of the School of Public Health, The University of Hong Kong (HKU).

“Four developmental trajectories of infant gut microbiota were identified in the study, with one trajectory [ie, C1-C1] characterized by persistently low level of gut Bacteroides abundance and high Enterobacteriaceae/Bacteroidaceae ratio throughout infancy,” said Tun.

“A number of factors, including methods of birth and feeding, presence of siblings and furry pets, as well as exposure to antibiotics and use of chemical disinfectants, influence microbial seeding and colonization in the first year of life, [ie, the window of opportunity for microbiota and immune development],” Tun explained.

“Compared with other trajectories, the C1-C1 trajectory was more commonly seen in infants delivered by Caesarean section [38.0 percent vs 7.7–36.9 percent] and in infants born to Asian mothers [23.1 percent vs 9.9–18.2 percent],” he pointed out.

The C1-C1 vs C2-C2 trajectory was associated with a 2.82-fold increase (95 percent confidence interval [Cl], 1.13 to 1.70) in risk of peanut sensitization at 3 years of age.

The risk of peanut sensitization at 3 years of age was further increased in infants with vs without the C1-C1 trajectory born to Asian vs non-Asian mothers (adjusted odds ratio, 7.87; 95 percent CI, 2.75 to 22.55).

The microbiome profile of infants with the C1-C1 trajectory was characterized by Clostridioides difficile colonization in late infancy, with an elevated risk of food and peanut sensitization throughout infancy, while a significant decrease in metabolism of sphingolipids (cellular membrane proteins implicated in immune system development and atopic disease) was detected in these infants born to Asian mothers.

“Infants born to Asian mothers, in particular, are suggested to be exposed to an environment with diverse microbes in the first 3 years of life based on the hygiene hypothesis, as an overly clean environment hampers the development of children’s immune system,” said Tun.

In the study, 2,844 faecal samples of 1,422 full-term infants from the Canadian Healthy Infant Longitudinal Development (CHILD) birth cohort were collected at early infancy (mean age, 3.4 months) and late infancy (mean age, 12.2 months) for faecal microbiota analysis via 16S ribosomal ribonucleic acid (rRNA) amplicon sequencing. Detection of C. difficile colonization was performed with quantitative polymerase chain reaction (qPCR).

Skin prick test (SPT) against 10 standardized inhalant allergens and common food allergens was done in the infants at 1 year of age, with seven additional inhalant allergens tested at 3 years of age, with histamine and glycerin regarded as positive and negative control, respectively.