DISCUSSION
ulcerative colitis, UC
DISEASE, REMISSION, ULCERATIVE COLITIS
In this study, we explored the clinical outcomes of capsulized FMT treatment in patients with active UC. We also performed a general analysis of the gut microbiota and serum metabolites to identify specific taxonomic, functional, and metabolite changes associated with clinical outcomes after FMT. Capsulized FMT could induce clinical remission in 57.1% (12 of 21) of patients with UC and clinical response in 76.2% (16 of 21) of patients at week 12. The gut microbiome and serum metabolites in samples obtained from patients were significantly altered after capsulized FMT treatment, especially at week 4. Improvements in microbial richness, depletion of opportunistic pathogens (The key features distinguishing this study from previous studies on FMT in UC patients were the low intensity of microbiota transplantation using capsules and the high efficiency of clinical remission. Previously, colonic transendoscopic tubes or enemas were the main methods used to deliver fecal microbiota transplantation, and the treatment cycle was relatively long. For example, Paramsothy et al. first achieved a single colonoscopic delivery of FMT to the right colon and then performed enemas 5 days per week for 8 weeks (Generally, if clinical symptoms were relieved 4 weeks after FMT, most patients could be in a stationary phase. The longer the time required for symptom remission, the worse the prognosis. We attempted to reveal the relationship between lesion regions (E1, E2, and E3) or disease severity and the clinical response, but there were no significant differences in the efficacy of capsulized FMT, indicating that the impact of capsulized FMT was unrelated to the lesion area and disease severity. We also observed remarkable and specific differences in gut microbiota and metabolites between the Rm and NRm groups at week 4 after FMT. Notably, previous studies also investigated changes in the microbiota at 4 weeks after FMT, and results show consistent trends (We also observed that microbial richness was significantly decreased in patients with UC compared to that in healthy individuals. However, microbial richness levels were improved to levels comparable to those of donors only in patients who achieved clinical remission at week 12 after FMT. Improvement of gut microbial richness after FMT has been reported in previous clinical studies on UC patients (Microbes and functional microbial pathways associated with clinical remission were further analyzed based on 16S rRNA gene and metagenomic data sets. Compared with the baseline, the increased relative abundance of species, including Serum metabolite profiles were significantly different between the baseline and week 4 after FMT. Among these profiles, elevated levels of indolelactic acid, PGH2-EA, and isohyodeoxycholic acid were associated with a favorable treatment output, while increased levels of 12,13-DiHOME were associated with worse outcomes. PGH2-EA, a prostaglandin, showed anti-inflammatory properties in ulcerative colitis (In general, we demonstrated the efficacy of FMT in patients with mild to severe UC through well-prepared donor stool capsules administered orally three times a week. Capsulized FMT could accelerate the metabolism of tryptophan by increasing the abundance of 