Wednesday, October 12, 2016
Early-life gut microbiome composition and milk allergy resolution
Allergy to cow’s milk affects roughly one in fifty children, rendering them at risk for potentially deadly allergic reactions as well as for poor nutrition that comes with avoiding cow’s milk. In this month’s issue of JACI, Bunyavanich and colleagues relay the results of their research on how gut bacteria might influence the course of this disease (J Allergy Clin Immunol 2016; 138(4): 1122-1130). They looked at the stools of 234 milk allergic children ranging in age from 3 to 16 months. They used 16s rRNA sequencing to profile the different types of gut bacteria and followed the children up to age 8 years.
They found that among children age 3 to 6 months, bacteria in the Firmicutes phylum and Clostridia class were associated with resolution of milk allergy by age 8 years. This is consistent with preliminary findings from mouse models that also show that Clostridia have a role in regulating sensitization to food allergens. However, these bacteria appear to have a very short time window to exert their effect, because there was no association in children beyond 6 months of age. It is possible that the immune systems of infants up to six months of age are easier to tolerize, or that the introduction of solid foods at around age 6 months obscures this association.
It is possible that the fatty acids produced by bacteria may have potent roles in reestablishing tolerance, but the study was not structured to answer that question. Other questions left to answer include whether supplementation with probiotics can help reestablish tolerance and whether introducing these bacteria would be safe.