Gut Microbial Protein Metabolism in Food Allergy and Oral Immunotherapy Efficacy - Project Summary/Abstract Food allergies are common and life-threatening pediatric conditions, predominantly triggered by specific protein motifs in foods, such as Ara h proteins in peanuts (e.g., Ara h 2). Allergen-specific oral immunotherapy (OIT), in which patients are exposed to increasing doses of allergens to desensitize their immune systems, has emerged as a promising treatment for food allergies. However, OIT induces sustained remission in only a fraction of food- allergic patients, and the factors contributing to treatment response remain elusive. My postdoctoral studies have identified strong relationships between the gut microbiome and the response to peanut OIT (POIT) in the IMPACT clinical trial. We found that children who did not respond to POIT have a distinct gut microbiome composition that is significantly enriched in the Xaa-Xaa-proline tripeptidyl-peptidase (ptpA) gene, which encodes a hydrolase that cleaves tripeptides with a proline residue at the third position from the N-terminal of polypeptides. The copy number of the ptpA gene positively correlates with peanut allergen component (Ara h 2) -specific IgE levels. Additionally, we showed that the gut microbiome can metabolize one of the most proteolysis- resistant allergenic peanut proteins, Ara h 2. The microbiome of those who failed to achieve POIT-induced remission exhibited a significantly increased capacity to metabolize Ara h 2 compared to those who achieved remission. This suggests that enhanced microbial metabolism of allergenic peanut proteins may be associated with POIT failure. This proposal comprises three interlinked but independent investigations. Study 1 will test whether interindividual response to POIT is associated with the gut microbial peanut protein metabolism and specific peanut proteins reaching the lower gastrointestinal tract. Study 1 will also investigate the molecular mechanisms by which the human gut microbiome metabolizes allergenic peanut proteins and aims to isolate specific gut microorganisms with peanut protein metabolism capacity. Study 2 will investigate the role of the gut microbial ptpA gene, which is enriched in POIT non-responders, in peanut protein metabolism. Study 3 will develop engineered probiotic bacteria to produce individual peanut Ara h proteins, offering a novel in situ immunotherapeutic production and delivery approach. Leveraging targeted proteomics, next-generation sequencing, in vitro bioreactor arrays, gnotobiotic mouse models, and clinical samples from the IMPACT clinical trial, this proposal aims to identify the molecular mechanisms by which the human gut microbiome affects POIT efficacy. This research, which bridges the gap between gut microbial protein metabolism and POIT efficacy, has the potential to enhance the effectiveness of OITs, bringing us closer to tailored treatments for food-allergic patients.
