Abstract
BACKGROUND: Food allergen immunotherapy can induce remission of food allergies in certain individuals, but the mechanisms underlying this remission are largely unknown. Prior work has identified differences in immunomodulatory metabolites between older children who develop remission versus non-remission on oral immunotherapy (OIT). Here we aim to characterize metabolomic changes during OIT in young children to and validate patterns of immunomodulatory metabolites previously observed. METHODS: Untargeted plasma metabolomic profiling was performed on samples from the DEVIL peanut OIT trial (n=41, ages 9-36 months). Remission status was determined by oral food challenges conducted at the end-of-therapy and the end of a 1-month avoidance period. Linear and logistic regression models were used to detect differences in individual metabolites over time on OIT and by remission status. Pathway analyses were used to determine enrichment of chemical subclasses and biological pathways. These pathways were then compared to prior findings generated from similar profiling performed from the PNOIT peanut OIT trial (n=20, ages 7-13). RESULTS: During OIT, glycerophospholipid metabolites (q=3.8×10 (-5) ) increased over time and most amino acid metabolites (q=6.1×10 (-45) ) decreased over time. Participants who went on to develop remission, had higher levels of amino acids (q=4.3×10 (-8) ) and bile acids (q=0.00014), whereas children who developed non-remission had higher levels of glycerophospholipids (q=4.3×10 (-10) ). Comparison of these findings with our second cohort of OIT in older children, showed replication of the enrichment of glycerophosphocholines (q=1.0×10 (-13) ) and amino acids (q=2.1×10 (-5) ) among metabolites that changed over time on OIT and replication of glycerophospholipids(q=5.7×10 (-16) ), amino acids ( PNOIT q=7.2×10 (-) (7) ), and bile acids ( PNOIT q=3.8×10 (-8) ) among metabolites that varied by remission status. CONCLUSIONS: Metabolomic profiles on OIT differed both over time on OIT and by OIT remission status in young children. Between two independent OIT cohorts of different ages we observed replication of significantly enriched chemical subclasses of glycerophospholipids, amino acids, and bile acids. Given the potentially immunomodulatory roles of some of these metabolites, our results suggest that glycerophospholipids, amino acids, and bile acids may be involved in the mechanisms of remission on OIT.