講演情報
[SY7-1]Right-sided Predominance of Primary Sclerosing Cholangitis–Associated Colitis: Insights from Gut Microbiota
*Haruka Okada1, Shinya Sugimoto1, Nobuhiro Nakamoto1, Ryosuke Kasuga1, Hiroki Kiyohara1, Hiroki Kiyohara1, Yohei Mikami1, Takanori Kanai1 (1. Division of Gastroenterology and Hepatology, Department of Internal Medicine, Keio University School of Medicine, Japan)
[Objective] Primary sclerosing cholangitis (PSC) is frequently associated with inflammatory bowel disease, and gut microbiota involvement has been suggested. We previously reported that Klebsiella pneumoniae (Kp) is frequently detected in PSC feces and is associated with disease activity and prognosis. PSC-associated colitis (PSC-colitis) is characterized by right-sided predominance, rectal sparing (RS), and backwash ileitis (BI); however, their frequencies vary among studies. This study aimed to investigate the significance of right-sided colitis by systematic evaluation of endoscopic images and by using a mouse model.
[Methods] We retrospectively analyzed PSC patients at our institution between January 2012 and July 2025. All colonoscopic images were reviewed, and PSC-colitis cases with evaluable active phase were included. For comparison, Ulcerative colitis (UC) without PSC (n = 3,419) were used to generate a 1:1 matched control group. In mice, PSC-derived Kp strains were orally administered, and their gut localization and bacterial translocation were quantitatively assessed.
[Results] Among 212 PSC patients, 170 (80.2%) had concomitant colitis. The majority (98.2%) exhibited a UC-like phenotype. In PSC with UC-like colitis and evaluable active phase endoscopy (n = 126), disease distribution was predominantly extensive (97.6%), with minimal left-sided (2.4%) and no proctitis, whereas UC-only patients showed extensive (66.7%), left-sided (20.6%), and proctitis (12.7%) (P < 0.001). RS and BI were significantly more frequent in PSC-colitis (92.1% vs. 11.1% and 24.1% vs. 3.2%, respectively; both P < 0.001). In mice, PSC-derived Kp preferentially accumulated in the ileocecal region and translocated to mesenteric lymph nodes draining this region.
[Conclusion] PSC-colitis is characterized by right-sided predominance, frequent RS and BI, and a phenotype distinct from UC. Preferential localization of PSC-derived Kp to the ileocecal region suggests a role for regional microbiota in the right-sided colon, consistent with gut–liver axis involvement.
[Methods] We retrospectively analyzed PSC patients at our institution between January 2012 and July 2025. All colonoscopic images were reviewed, and PSC-colitis cases with evaluable active phase were included. For comparison, Ulcerative colitis (UC) without PSC (n = 3,419) were used to generate a 1:1 matched control group. In mice, PSC-derived Kp strains were orally administered, and their gut localization and bacterial translocation were quantitatively assessed.
[Results] Among 212 PSC patients, 170 (80.2%) had concomitant colitis. The majority (98.2%) exhibited a UC-like phenotype. In PSC with UC-like colitis and evaluable active phase endoscopy (n = 126), disease distribution was predominantly extensive (97.6%), with minimal left-sided (2.4%) and no proctitis, whereas UC-only patients showed extensive (66.7%), left-sided (20.6%), and proctitis (12.7%) (P < 0.001). RS and BI were significantly more frequent in PSC-colitis (92.1% vs. 11.1% and 24.1% vs. 3.2%, respectively; both P < 0.001). In mice, PSC-derived Kp preferentially accumulated in the ileocecal region and translocated to mesenteric lymph nodes draining this region.
[Conclusion] PSC-colitis is characterized by right-sided predominance, frequent RS and BI, and a phenotype distinct from UC. Preferential localization of PSC-derived Kp to the ileocecal region suggests a role for regional microbiota in the right-sided colon, consistent with gut–liver axis involvement.