PROJECT SUMMARY Ulcerative colitis (UC) is an inflammatory bowel disease of the large intestine, impacting millions worldwide. UC patients commonly experience significant weight loss, diarrhea, bloody stool, decreased quality of life, and susceptibility to colon cancer. Current medications for UC include antibiotics, corticosteroids, and biological drugs, which can have deleterious off-target effects that contribute to increased susceptibility to severe infections and chronic immunosuppression. Thus, there is a need to develop safe and effective strategies to treat UC. Although the pathogenesis of UC is vague, evidence suggests that disrupted interactions between the host immune system and the gut microbiome play a role in the disease initiation and progression. Indeed, most UC symptoms are believed to be caused by an imbalance between mucosal immunity and intestinal microbiota resulting in excessive intestinal inflammation. Similarly, microbial metabolites have been implicated as key regulators of the intestinal barrier contributing to UC pathogenesis. Thus, improving the immune, microbiome, and metabolite signatures may improve clinical outcome for UC patients. Natural products have been the most significant source of drugs and drug leads in history and have shown promise in treating UC with fewer side- effects. We have identified that panaxynol (Pax), a bioactive component of American ginseng, can suppress colitis and improve disease severity. My data demonstrates that Pax-treated mice display 1) improved disease activity index, 2) better endoscopic scores, 3) greater intestinal barrier function 4) reduced crypt distortion, 5) decreased goblet cell and mucus loss, 6) enhanced differentiation of Tregs, and 7) suppression of pro-colitis gut bacterial populations in a mouse model of colitis. Its exact underlying mechanism, however, remains unclear. Under the auspices of this F31, I will expand my current findings to examine immune, microbiome, and metabolite signatures as potential mediators of the benefits of Pax in colitis. Thus, the primary purpose of my proposed F31 is to understand the mechanisms whereby Pax improves gut resilience in colitis. To accomplish this, I will utilize multiple models of colitis, a clinically attainable Pax dose, both male and female mice, immune, microbiome, metabolite profiling, and mechanistic approaches (immune and microbiome ablation strategies). My central hypothesis is that the beneficial effects of Pax in colitis are mediated via its actions on the host immune system and the gut microbiome and metabolites. To test this hypothesis, I propose two related but independent aims: 1) Characterize the immune profile following Pax treatment in colitis; 2) Determine whether the microbiome contributes to Pax-mediated improvements in colitis. The proposed studies align with my training aims and will provide me with the opportunity to gain expertise in immune profiling and ablation strategies, assessment and manipulation of the microbiome, and examination of microbial metabolites and omics in the context of natural products and colitis. Further, the professional development training will promote advancement to the next step in my path to research independence – a postdoctoral position in the field of gut health.

PROJECT NARRATIVE Ulcerative colitis (UC), a chronic disease that is characterized by diffuse inflammation of the colonic and rectal mucosa, is rising globally. Current medications for UC include antibiotics, corticosteroids, and biological drugs, which can have deleterious off-target effects, contributing to increased susceptibility to severe infections and chronic immunosuppression. Building from our recent work documenting that dietary panaxynol, a bioactive component of American Ginseng, can mitigate colitis, I am proposing to examine immune, microbial and metabolite signatures to establish the potential mechanisms mediating panaxynol’s benefits in colitis.