Early-life fecal metabolomics of food allergy

Abstract

Background: Intestinal microenvironmental perturbations may increase food allergy risk. We hypothesize that children with clinical food allergy, those with food sensitization, and healthy children can be differentiated by intestinal metabolites in the first years of life.

Methods: In this ancillary analysis of the Vitamin D Antenatal Asthma Reduction Trial (VDAART), we performed untargeted metabolomic profiling in 824 stool samples collected at ages 3-6 months, 1 year and 3 years. Subjects included 23 with clinical food allergy at age 3 and/or 6 years, 151 with food sensitization but no clinical food allergy, and 220 controls. We identified modules of correlated, functionally related metabolites and sought associations of metabolite modules and individual metabolites with food allergy/sensitization using regression models.

Results: Several modules of functionally related intestinal metabolites were reduced among subjects with food allergy, including bile acids at ages 3-6 months and 1 year, amino acids at age 3-6 months, steroid hormones at 1 year, and sphingolipids at age 3 years. One module primarily containing diacylglycerols was increased in those with food allergy at age 3-6 months. Fecal caffeine metabolites at age 3-6 months, likely derived from breast milk, were increased in those with food allergy and/or sensitization (beta = 5.9, 95% CI 1.0-10.8, p = .02) and were inversely correlated with fecal bile acids and bilirubin metabolites, though maternal plasma caffeine levels were not associated with food allergy and/or sensitization.

Conclusions: Several classes of bioactive fecal metabolites are associated with food allergy and/or sensitization including bile acids, steroid hormones, sphingolipids, and caffeine metabolites.

Keywords: bile acids; caffeine; food allergy; food sensitization; metabolomics.

Figure 1.

Study design overview. Abbreviations: sIgE = serum specific IgE to foods.

Figure 2.

A. Caffeine metabolic pathway. Metabolites in the fecal caffeine metabolite module are displayed with purple background. Figure modified from KEGG Caffeine metabolism reference pathway B. Fecal caffeine metabolite module from age 3-6 months. Displayed by association of individual metabolites with food allergy/sensitization (y axis, adjusted odds ratio) and by module membership (correlation of individual metabolite with module eigenvalue, x axis).

Figure 3.

Violin plots depict associations between the fecal caffeine metabolite module and whether subjects were ingesting breast milk and not ingesting formula at the time of stool sample collection. In metabolomics batch 1, 27 subjects were breastfed and 55 were not breastfed; in batch 2, 31 were breastfed and 92 not breastfed.

Figure 4.

Scatterplots depict associations between food allergy/sensitization-associated fecal intestinal bile acid/bilirubin and caffeine modules from stool samples collected at age 3-6 months. Metabolomics Batch 1 Pearson rho=−0.49, p=2e-6, Batch 2 rho=−0.33, p=0.0002.