Infant gut microbiome seems to shape allergy risk by altering immune responses
September 15, 2016
The microbial communities, or microbiota, that naturally colonize the digestive tract in very young infants can affect their risk of later developing childhood allergies and asthma. Scientists now have identified a specific type of microbiota composition and corresponding metabolic environment in the neonatal gut that appears to influence immune cell populations and promote allergy and asthma development. The work was funded by the National Institute of Allergy and Infectious Diseases (NIAID), part of the National Institutes of Health.
A team led by researchers at the University of California, San Francisco, and Henry Ford Health System in Detroit analyzed stool samples collected from 298 neonates and infants and categorized them into groups based on the compositions of their gut microbiota. They found three different gut microbial compositions in neonates (aged 16 to 137 days), one of which was associated with an increased risk for many allergies at 2 years of age and asthma at age 4. The high-risk group had a relatively lower abundance of certain bacteria and an increased abundance of specific fungi.
Taking a step further, the scientists identified a relationship between the type of neonatal gut microbiota and the metabolome–the set of small-molecule products, or metabolites, resulting from the breakdown of proteins, fats and so on. When the researchers exposed immune cells from healthy adult donors to sterile metabolite mixtures extracted from the stool of high-risk infants, the proportion of allergy-promoting immune cells in the samples increased, as did production of an allergy-associated cell-signaling protein. In contrast, the proportion of cells that protect against allergy decreased. Exposing the healthy immune cells to a metabolite called 12,13-DiHOME, which was enriched in the stool of the high-risk infants, caused a similar decrease in allergy-protective cells.
Together, these results suggest that the composition of microbial communities and the related microbe-associated metabolites in the gut of very young infants contribute to their risk of developing allergies and asthma during childhood. Although more work is needed, the findings eventually may help advance development of early-life interventions to prevent allergies and allergic diseases.