DOP39 Constructing butyrate-producing yeast as a cell-dependent treatment option for Inflammatory Bowel Disease

Abstract Background Intestinal microbiota dysbiosis and metabolic disruption are essential characteristics of inflammatory bowel disorders (IBD). Butyrate has been proven to regulate immune response and gut microbiota. It has been confirmed that the butyrate content in the intestinal cavity of IBD patients decreases (Fig. 1A). Methods In this study, gene editing was used to reconstruct the butyrate synthesis pathway and regulate related metabolic pathways in Saccharomyces cerevisiae to produce butyrate and enrich its synthesis in anaerobic environments to cope with complex intestinal conditions. A series of engineered strains were co-cultured with gut microbiota samples from six patients with mild-to-moderate ulcerative colitis and 16S ribosomal RNA sequencing was used to analyze the regulatory effect of engineered strains on intestinal microbiota in vitro. The TNBS-induced IBD mice model was used to explore the protective effect of butyrate-engineered yeasts in vivo. Results A series of engineered strains with different butyrate synthesis abilities was constructed to meet the needs of different patients. S. cerevisiae was engineered by introducing an exogenous butyrate synthesis pathway and regulating yeast metabolism to increase the availability of the precursors. Engineered yeast can produce up to 1.8 g/L butyrate (Fig. 1B). The modification of related metabolic pathways also focused on enhancing the synthesis of butyrate under anaerobic conditions to enable engineered yeasts to adapt to the intestinal environment. This series of engineered yeasts with different butyrate synthesis abilities regulated the intestinal microbiota of IBD patients to varying degrees, enhancing the abundance of related probiotics such as Lactobacillus and Bifidobacterium and reducing the abundance of harmful bacteria like Candidatus Bacilloplasma (Fig. 1C). Meanwhile, strains improved TNBS-induced colitis in mice by restoring butyrate content. Remarkably, the engineered strain with the second-highest butyrate yield showed the most significant therapeutic effect (Fig. 1D). Conclusion This study realized butyrate synthesis in S. cerevisiae and regulated related metabolic modules to adjust the butyrate production to achieve the best therapeutic effect on colitis in vivo and in vitro. In addition, the strain with the second-highest butyrate production has the best therapeutic effect. This highlights the dual role of butyrate in epithelial cell repair and suggests a therapeutic window for IBD treatment through butyrate supplementation. Selecting the most suitable strain for each patient's condition is essential for restoring butyrate levels, regulating microbiota, and promoting mucosal repair.