P424 Analysis of the intestinal microbiome using an Endoscopic Brush in Ulcerative colitis

Background The precise pathogenesis of the Ulcerative colitis is still yet unknown, but one of its cause is known to be microbial dysbiosis. The mucosa-associated microbiota are more deeply involved in the pathogenesis of UC. However, the optimal sampling of mucosa-associated microbiome has yet to be investigated. In this study, we investigated the mucosa-associated microbiome in patients with ulcerative colitis, using endoscopic brush samples. We hypothesized that endoscopic brushing is precise and noninvasive method to get sample of mucosa-associated microbiome. Methods Patients with UC who visited the gastroenterology department of Korea University Anam hospital were screened for this study. Clinical data such as medical records, colonoscopy and fecal samples were reviewed. Using a stool and saliva sample collector kit respectively, the subjects provided stool and saliva samples. Brushing samples were collected during the sigmoidoscopy procedure with 3-4 brush strokes on the colon mucosa using the cytology brush. The samples were analyzed for microbiome in the Korea University Medical Center. Results From July 2022 to January 2023, we prospectively enrolled 19 patients with UC. Firmicutes, Bacteroidetes, Proteobacteria, and Actinobacteria were the most common species in microbiota of brush, stool and saliva.(Fig.1-1) The microbiome between stool and brush was no significant difference in alpha and beta diversities.(Fig.1-2) However, Oral microbiome was different from stool and brush in beta diversities.(Fig.1-3) Patients were categorized into to analyze the oral microbiome. A trend was observed where increased disease severity was associated with an increase in Firmicutes.(Fig.1-4) Conclusion The microbiome of stool and brush was no significantly different. However, the novel sampling of mucosa-associated microbiome, endoscopic brush, is not inferior compared to currently used sampling of stool. Also the analysis of the oral microbiome suggested that Firmicutes could be considered a useful biomarker for assessing disease severity. Therefore, it is necessary to conduct followup research by increasing the number of subjects.