Fecal microbiome transplant in food allergy in humans and mice identifies a role for bile acid metabolites in oral tolerance.

In responders, fecal microbiome transplantation increased tolerogenic RORγt + regulatory T cells (T reg cells) and decreased T helper 2 cells (T H 2 cells).

In both humans and mice, protection by fecal microbiome transplantation was associated with increased bile acid metabolites.

Deletion of a bile salt hydrolase in a candidate protective Bacteroides abrogated food allergy suppression in mice.