Mechanisms of food-specific antibody induction in the gut

The rate of food allergy diagnosis in the United States has been increasing over the past few decades, with more than 32 million Americans affected. Food allergies are caused by pathogenic, food-specific immunoglobulin E (IgE) antibodies. It is not fully understood why some people make allergenic IgE food-specific antibodies when the default response to food is oral tolerance. Using a mouse model of oral peanut exposure to screen environmental triggers for their ability to promote the production of food-specific IgE, we discovered that a lipid called alpha-galactosylceramide (α-GalCer) was able to induce anaphylactic peanut-specific IgE. Mechanistically we identified an α-GalCer-dependent pathway that required invariant natural killer T (iNKT) cells, type 2 conventional DCs (cDC2s), and T follicular helper (Tfh) cells for peanut IgE production. Despite evidence that iNKT cells are involved in allergy, mechanisms by which iNKT cell activation leads to IgE to food production are unknown. While α-GalCer itself is unlikely to act as the environmental trigger of food allergy, we hypothesize that specific lipids in the diet or microbiome are presented by gut cDC2s to a subset of pro-allergenic iNKT cells, which promote the priming of Tfh13 cells that drive food-specific IgE. In this proposal, we will define how these three immune cells work in concert to promote the production of food-specific IgE. In addition, we will test if other lipids can promote the production of food-specific IgE, through iNKT and other lipid-restricted T cell mechanisms. In Aim 1 we will determine how iNKT cell activation promotes Tfh cell-dependent food- specific IgE production. Using flow cytometry and single-cell RNA-Sequencing will identify gut iNKT subsets that are activated following oral immunization with α-GalCer and peanut and will determine the cytokines and co- stimulatory signals they produce. In Aim 2 we will test whether exposure to environmental lipids induces food- specific IgE. We will screen naturally occurring lipids from food and microbial sources to determine whether they can activate iNKT cells and promote the production of peanut-specific IgE in a manner similar to α-GalCer. Using human CD1 transgenic mouse model we will also determine whether human CD1-restricted, lipid-specific murine NKT cells can promote peanut-specific IgE responses after peanut and food lipid exposure. In Aim 3 we will identify which antigen presenting cells coordinate the activation of iNKT cells and priming of Tfh cells in the production of iNKT cell-dependent food-specific IgE. Once completed, this work will define the mechanisms of how iNKT cell-induced anaphylactic IgE to food allergens is produced, revealing new cellular pathways that could potentially be targeted to prevent the development of food allergy. Project Number: 1R01AI195448-01 | Fiscal Year: 2026 | NIH Institute/Center: National Institute of Allergy and Infectious Diseases (NIAID) | Principal Investigator: Stephanie Eisenbarth (+1 co-PI) | Institution: NORTHWESTERN UNIVERSITY AT CHICAGO, CHICAGO, IL | Award Amount: $493,889 | Activity Code: R01 | Study Section: Special Emphasis Panel[ZRG1 IMHA-B (01)] View on NIH RePORTER: https://reporter.nih.gov/project-details/1R01AI19544801