Yoo Min Han

Background: Inflammatory bowel diseases (IBDs) are heterogeneous disorders in which gut microbial dysbiosis may influence disease activity and clinical outcomes. However, it remains unclear whether microbiome-based stratification identifies clinically relevant IBD subtypes. Methods: We profiled the gut microbiome of a cohort comprising patients with IBD (n = 260), at-risk individuals (n = 166), and healthy control individuals (n = 57) using 16S rRNA gene amplicon sequencing. Unsupervised clustering was used to define gut microbial enterotypes. Associations with clinical characteristics and outcomes, including fecal calprotectin levels and medication step-up, were evaluated. Statistical and machine learning approaches were applied to identify enterotype-specific microbial signatures. Results: Four enterotypes were identified and labeled according to their most discriminative genera: Faecalibacterium and Blautia, Prevotella, Phocaeicola, and Bifidobacterium with reduced Faecalibacterium (Bif + Faec-low). Faecalibacterium and Blautia and Prevotella were enriched in healthy control individuals, Phocaeicola was enriched in at-risk individuals, and Bif + Faec-low was enriched in patients with IBD. The Bif + Faec-low enterotype was associated with lower body mass index, higher fecal calprotectin levels, and an increased risk of medication step-up (hazard ratio, 1.71; 95% confidence interval, 1.10-2.66). Microbial composition and network analyses identified distinct enterotype-specific taxa and hub genera, suggesting functional divergence among enterotypes. Conclusions: Gut microbial enterotypes are associated with distinct clinical phenotypes and treatment escalation in IBD, and exhibit enterotype-specific microbial community structures and alterations across disease states. Enterotype-based stratification may provide a clinically relevant framework for assessing risk assessment and guiding personalized disease management.

Background Clostridioides difficile infection (CDI) frequently occurs concurrently in patients with inflammatory bowel disease (IBD), and differential diagnosis from IBD flares is critical. However, clinical management of C. difficile in IBD patients with polymerase chain reaction toxin-positive (tPCR+)/enzyme immunoassay toxin-negative (tEIA−) results has not yet been investigated. Aims We aimed to assess the clinical significance of C. difficile tPCR+/tEIA− in patients with IBD and the impact of antibiotic treatment on IBD outcomes. Methods This single-center, retrospective cohort study included patients with IBD with CDI test results between January 01, 2018, and August 01, 2022. First, the clinical outcomes of IBD, such as medication escalation, hospitalization, and surgery, were compared between patients with IBD with tPCR−/tEIA− and those with tPCR+/tEIA− using Cox regression and propensity score matching. Next, the clinical outcomes of IBD were assessed based on whether antibiotic treatment for CDI was administered to both groups. Results Among 412 patients with IBD with PCR test, 71 (17.2%) showed tPCR+/tEIA− results. The tPCR+/tEIA− group showed no statistically significant difference in IBD outcomes compared to the tPCR−/tEIA− group. The antibiotic-treated tPCR+/tEIA− group showed a higher risk of drug escalation and admission than the tPCR−/tEIA− group, while the antibiotic-untreated tPCR+/tEIA− group did not. After drug escalation during the follow-up, the treated tPCR+/tEIA− group showed IBD outcomes similar to those of the tPCR−/tEIA− group. Conclusions In patients with IBD with indeterminate CDI, the need for antibiotics should be thoroughly assessed and proper management of underlying IBD such as drug escalation may lead to favorable outcomes.

The incidence of cancer and its associated mortality have increased over the past several decades

Han YM, et al. Clin Hypertens. 2025 Oct;31(1):e30. https://doi.org/10.5646/ch.2025.31.e30

Han YM, et al. Clin Hypertens. 2025 Jun;31(1):e22. https://doi.org/10.5646/ch.2025.31.e22

Jooyoung Lee, Woo Sang Cho, Byeong Soo Kim, Dan Yoon, Jung Kim, Ji Hyun Song, Sun Young Yang, Seon Hee Lim, Goh Eun Chung, Ji Min Choi, Yoo Min Han, Hyoun-Joong Kong, Jung Chan Lee, Sungwan Kim, Jung Ho Bae. Gut and Liver 2024;18:857-66. https://doi.org/10.5009/gnl240068

INTRODUCTION: Visceral obesity is a risk factor for reflux esophagitis (RE). We investigated the risk of RE according to visceral adipose tissue (VAT) measured by deep neural network architecture using computed tomography (CT) and evaluated the longitudinal association between abdominal adipose tissue changes and the disease course of RE. METHODS: Individuals receiving health checkups who underwent esophagogastroduodenoscopy (EGD) and abdominal CT at Seoul National University Healthcare System Gangnam Center between 2015 and 2016 were included. Visceral and subcutaneous adipose tissue areas and volumes were measured using a deep neural network architecture and CT. The association between the abdominal adipose tissue area and volume and the risk of RE was evaluated. Participants who underwent follow-up EGD and abdominal CT were selected; the effects of changes in abdominal adipose tissue area and volume on RE endoscopic grade were investigated using Cox proportional hazards regression. RESULTS: We enrolled 6,570 patients who underwent EGD and abdominal CT on the same day. RE was associated with male sex, hypertension, diabetes, excessive alcohol intake, current smoking status, and levels of physical activity. The VAT area and volume increased the risk of RE dose-dependently. A decreasing VAT volume was significantly associated with improvement in RE endoscopic grade (hazard ratio: 3.22, 95% confidence interval: 1.82–5.71). Changes in subcutaneous adipose tissue volume and the disease course of RE were not significantly correlated. DISCUSSION: Visceral obesity is strongly associated with RE. VAT volume reduction was prospectively associated with improvement in RE endoscopic grade dose-dependently. Visceral obesity is a potential target for RE treatment.