Fecal IgE Analyses Reveal a Role for Stratifying Peanut-Allergic Patients

Peanut allergy (PA) is an IgE-mediated food allergy with variable clinical outcomes. Mild to-severe symptoms affect various organs and, often, the gastrointestinal tract. The role of intestine-derived IgE antibodies in gastrointestinal PA symptoms is poorly understood. Objective: This study aimed to examine fecal IgE responses in PA as a novel approach to patient endotyping.

Feces and serum samples were collected from peanut-allergic and healthy children (n=26) to identify IgE and cytokines using multiplex assays. Shotgun metagenomics DNA sequencing and allergen database comparisons made it possible to identify microbial peptides with homology to known allergens.

Compared to controls, fecal IgE signatures showed broad diversity and increased levels for 13 allergens, including food, venom, contact, and respiratory allergens (P<.01-.0001). Overall, fecal IgE patterns were negatively correlated compared to sera IgE patterns in PA patients, with the greatest differences recorded for peanut allergens (P<.0001). For 83% of the allergens recognized by fecal IgE, we found bacterial homologs from PA patients' gut microbiome (eg, thaumatin-like protein Acinetobacter baumannii vs Act d 2, 109/124 aa identical). Compared to controls, PA patients had higher levels of fecal IgA, IL-22, and auto-IgE binding to their own fecal proteins (P<.001). Finally, levels of fecal IgE correlated with abdominal pain scores (P<.0001), suggesting a link between local IgE production and clinical outcomes.

Fecal IgE release from the intestinal mucosa could be an underlying mechanism of severe abdominal pain through the association between leaky gut epithelia and anticommensal TH2 responses in PA.