P1351 Microbiome Diversity and Taxonomic Differences in Quiescent Ulcerative Colitis: A Comparative Study of Proximal Extension
Authors: Kang MD.- PhD. S B , Jung S H , Lee K M 
Published: January 2025

Abstract

Background
The gut microbiome plays a significant role in ulcerative colitis (UC) pathogenesis, but its contributions during clinical remission and in relation to disease extent remain underexplored. This study investigates the microbiome profiles of quiescent UC patients with proximal extension (Y) and those without proximal extension (N), aiming to identify microbiome-based differences and potential biomarkers for disease stratification.

Methods
Fecal microbiome samples were obtained from 30 quiescent UC patients: 17 without proximal extension (N) and 13 with proximal extension (Y). Sequencing data were processed to exclude human genome reads, and rarefaction curves were used to ensure data quality. Alpha- and beta-diversity metrics assessed microbial diversity within and between groups. Differentially abundant taxa were identified, and a random forest model was employed to classify patients based on microbial composition.

Results: Diversity Analysis
Alpha-diversity showed no significant differences between the N and Y groups.Beta-diversity analysis revealed no distinct clustering between groups (P = 0.44), indicating shared microbial community structures.

Taxonomic Composition
The Y group (proximal extension) showed higher abundances of taxa such as Bartonella birtlesii, Lactobacillus salivarius, Klebsiella sp. M5al, and Proteus vulgaris.
The N group (no proximal extension) was enriched with taxa like Lactococcus lactis and Pediococcus acidilactici.

Machine Learning Classification
The random forest model successfully classified patients into N and Y groups based on microbial features. Key predictive taxa aligned with findings from differential abundance analyses, reinforcing their potential as biomarkers.

Conclusion
This study highlights distinct microbiome signatures between UC patients with and without proximal extension during remission. While diversity metrics were similar, specific taxa showed significant differences in abundance. These findings may inform microbiome-based diagnostic and therapeutic approaches tailored to disease extent. Further research is required to validate these results and explore the underlying mechanisms driving microbiome-disease interactions.

References
1.Kang DY, Park JL, Yeo MK, Kang SB, Kim JM, Kim JS, Kim SY. Diagnosis of Crohn's disease and ulcerative colitis using the microbiome. BMC Microbiol. 2023 Nov 11;23(1):336. doi: 10.1186/s12866-023-03084-5.
2.Guo XY, Liu XJ, Hao JY. Gut microbiota in ulcerative colitis: insights on pathogenesis and treatment. J Dig Dis. 2020 Mar;21(3):147-159. doi: 10.1111/1751-2980.12849.
3.Hsia K, Zhao N, Chung M et al. Alterations in the Fungal Microbiome in Ulcerative Colitis. Inflamm Bowel Dis. 2023 Oct 3;29(10):1613-1621. doi: 10.1093/ibd/izad082.
4.Fang J, Wang H, Zhou Y el al. Slimy partners: the mucus barrier and gut microbiome in ulcerative colitis. Exp Mol Med. 2021 May;53(5):772-787.
5.Bullard BM, VanderVeen BN, McDonald SJ, Cardaci TD, Murphy EA. Cross talk between the gut microbiome and host immune response in ulcerative colitis: nonpharmacological strategies to improve homeostasis. Am J Physiol Gastrointest Liver Physiol. 2022 Dec 1;323(6):G554-G561. doi: 10.1152/ajpgi.00210.2022.
6.Basha OM, Hafez RA, Salem SM, Anis RH, Hanafy AS. Impact of gut Microbiome alteration in Ulcerative Colitis patients on disease severity and outcome. Clin Exp Med. 2023 Sep;23(5):1763-1772. doi: 10.1007/s10238-022-00917-x.
7.Roda G, Narula N, Pinotti R et al. Systematic review with meta-analysis: proximal disease extension in limited ulcerative colitis. Aliment Pharmacol Ther. 2017 Jun;45(12):1481-1492. doi: 10.1111/apt.14063.