IDDF2024-ABS-0288 Engineered probiotic with high tryptophan synthesis capability protects against inflammatory bowel disease

<h3>Background</h3> Aberrant L-tryptophan metabolism has been implicated in the pathogenesis of inflammatory bowel disease (IBD). Here, we engineered a probiotic, which in conjunction with microcapsule-aided delivery to the colon, rectifies colon tryptophan metabolism and alleviates IBD in mice. <h3>Methods</h3> Probiotic EcN was genetically engineered to establish the EcN-TRP strain, with enhanced capacity to produce tryptophan. EcN-TRP was encapsulated in a dual-layered, pH-responsive microcapsule (EcN-TRP@A/G) through high-voltage electrospinning and liquid interface self-assembly. Murine IBD models were induced by DSS or TNBS, and they were orally administered with EcN-TRP@A/G. <h3>Results</h3> EcN-TRP significantly increased the capacity for tryptophan synthesis, achieving a production level &gt;370 times that of native EcN. EcN-TRP@A/G microcapsules largely preserved EcN-TRP viability under acidic conditions of the upper gastrointestinal tract and facilitated targeted release in the colon, with a 22.8-fold increase in delivery to the mouse colon compared to naked EcN-TRP by bioluminescent tracking. Metabolomic profiling validated that EcN-TRP@A/G significantly modulated tryptophan and indole metabolites indole-3-acetic acid (IAA) and indole-3-propionic acid (IPA) in the mouse colon for up to 7 days after a single dose. Concordantly, EcN-TRP@A/G administration significantly ameliorated DSS- or TNBS-induced IBD in mice and was effective in both preventive and treatment settings. Mechanistically, EcN-TRP@A/G restored gut barrier function, inhibited inflammation and reduced colon epithelial cell apoptosis in IBD mouse models. EcN-TRP@A/G also recovered gut microbial homeostasis by enriching beneficial bacteria such as <i>Prevotellaceae_</i>UCG-001 and <i>Anaerostipes</i>, together with the depletion of pathogenic strains like <i>Escherichia-Shigella</i>. Notably, some of the enriched probiotics are known to metabolize indole metabolites, suggesting the metabolic cross-feeding of EcN-TRP@A/G and other gut microbes to generate indole metabolites that confer synergistic effects against IBD. <h3>Conclusions</h3> EcN-TRP@A/G formulation is a safe and cost-effective approach for the prevention and treatment of IBD.