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Fecal samples were collected from 640 individuals in Korea, including 523 patients with IBD (223 with Crohn's disease [CD] and 300 with ulcerative colitis [UC]) and 117 healthy controls. The samples were subjected to cross-sectional gut metagenomic analysis using 16 S rRNA sequencing and bioinformatics analysis. Patients with IBD, particularly those with CD, exhibited significantly lower alpha diversities than the healthy subjects. Differential abundance analysis revealed dysbiotic signatures, characterized by an expansion of the genus Escherichia-Shigella in patients with CD. Functional annotations showed that functional pathways related to bacterial pathogenesis and production of hydrogen sulfide (H2S) were strongly upregulated in patients with CD. A dysbiosis score, calculated based on functional characteristics, highly correlated with disease severity. Markers distinguishing between healthy subjects and patients with IBD showed accurate classification based on a small number of microbial taxa, which may be used to diagnose ambiguous cases. These findings confirm the taxonomic and functional dysbiosis of the gut microbiota in patients with IBD, especially those with CD. Taxa indicative of dysbiosis may have significant implications for future clinical research on the management and diagnosis of IBD. [ABSTRACT FROM AUTHOR]

Background and Aim: The global inflammatory bowel disease (IBD) escalation has precipitated an increased disease burden and economic impact, particularly in Asia. This study primarily aimed to predict the future prevalence of IBD in Korea and elucidate its evolution pattern. Methods: Using a validated diagnostic algorithm, we analyzed data from the Korean National Health Insurance Service between 2004 and 2017 to identify patients with IBD. We predicted the number and prevalence of patients with IBD from 2018 to 2048 with the autoregressive integrated moving average method. A generalized linear model (GLM) was also employed to identify factors contributing to the observed trend in IBD prevalence. Results: Our prediction model validation demonstrated an acceptable error range for IBD prevalence, with a 2.45% error rate and a mean absolute difference of 2.61. We foresee a sustained average annual increase of 4.51 IBD cases per 100 000, culminating in a prevalence of 239.73 per 100 000 by 2048. The forecasted average annual percent change was 6.17% for males and 2.75% for females over the next 30 years. The GLM analysis revealed that age, gender and time significantly impact the prevalence of IBD, with notable disparities observed between genders in specific age groups for both Crohn's disease and ulcerative colitis (all interaction P < 0.05). Conclusions: Our study forecasts a notable increase in Korean IBD prevalence by 2048, particularly among males and the 20–39 age group, highlighting the need to focus on these high‐risk groups to mitigate the future disease burden. [ABSTRACT FROM AUTHOR]

Background and Aims Crohn's disease [CD] has a complex polygenic aetiology with high heritability. There is ongoing effort to identify novel variants associated with susceptibility to CD through a genome-wide association study [GWAS] in large Korean populations. Methods Genome-wide variant data from 902 Korean patients with CD and 72 179 controls were used to assess the genetic associations in a meta-analysis with previous Korean GWAS results from 1621 patients with CD and 4419 controls. Epistatic interactions between CD-risk variants of interest were tested using a multivariate logistic regression model with an interaction term. Results We identified two novel genetic associations with the risk of CD near ZBTB38 and within the leukocyte immunoglobulin-like receptor [LILR] gene cluster [ p  < 5 × 10−8], with highly consistent effect sizes between the two independent Korean cohorts. CD-risk variants in the LILR locus are known quantitative trait loci [QTL] for multiple LILR genes, of which LILRB2 directly interacts with various ligands including MHC class I molecules. The LILR lead variant exhibited a significant epistatic interaction with CD-associated regulatory variants for TAP2 involved in the antigen presentation of MHC class I molecules [ p  = 4.11 × 10−4], showing higher CD-risk effects of the TAP2 variant in individuals carrying more risk alleles of the LILR lead variant (odds ratio [OR] = 0.941, p  = 0.686 in non-carriers; OR = 1.45, p  = 2.51 × 10−4 in single-copy carriers; OR = 2.38, p  = 2.76 × 10−6 in two-copy carriers). Conclusions This study demonstrated that genetic variants at two novel susceptibility loci and the epistatic interaction between variants in LILR and TAP2 loci confer a risk of CD. [ABSTRACT FROM AUTHOR]

Aim: To analyze the correlation between intestinal ultrasound (IUS) and serum and fecal biomarkers, and the characteristics of small bowel disease, for the assessment of active bowel inflammation. Methods: Patients with Crohn's disease (CD) who underwent an initial IUS examination between July 2018 and November 2022 at our institution were included retrospectively. We divided small and large bowels into seven segments, and recorded the presence of active inflammation according to following criteria: bowel wall thickness ≥ mm with ≥1 of feature of active disease on IUS. The correlations between IUS‐assessed activity and serum C‐reactive protein (CRP, mg/dL) and fecal calprotectin (FC, μg/g) levels were analyzed. Results: A total of 127 patients were included (mean age: 32.42 ± 12.07, M:F = 90:37, median disease duration 6 years [0–35]). Of them, 78 showed active bowel inflammation (61.4%), with inflammation distal to the terminal ileum being the most common disease location (n = 61, 78.2%). FC and serum CRP levels were significantly correlated with the number of segments with active inflammation (rho = 0.58, 0.48), number of segments with complications (r = 0.35, 0.31), and US activity score (r = 0.62, 0.54). With FC cutoff values of 100 and 150 μg/g, the concordance rates for patients with active small bowel disease were 78.7% (26/33) and 72.7% (24/33), respectively, which were better than those for other disease locations. Conclusions: Disease activity determined by IUS was significantly correlated with the biomarkers, with a better concordance rate in patients with active small bowel disease than in those with other disease locations with FC cut‐off values of 100 and 150 μg/g. [ABSTRACT FROM AUTHOR]

We investigated whether the response to anti-tumor necrosis factor (anti-TNF) treatment varied according to inflammatory tissue characteristics in Crohn's disease (CD). Bulk RNA sequencing (RNA-seq) data were obtained from inflamed and non-inflamed tissues from 170 patients with CD. The samples were clustered based on gene expression profiles using principal coordinate analysis (PCA). Cellular heterogeneity was inferred using CiberSortx, with bulk RNA-seq data. The PCA results displayed two clusters of CD-inflamed samples: one close to (Inflamed_1) and the other far away (Inflamed_2) from the non-inflamed samples. Inflamed_1 was rich in anti-TNF durable responders (DRs), and Inflamed_2 was enriched in non-durable responders (NDRs). The CiberSortx results showed that the cell fraction of activated fibroblasts was six times higher in Inflamed_2 than in Inflamed_1. Validation with public gene expression datasets (GSE16879) revealed that the activated fibroblasts were enriched in NDRs over Next, we used DRs by 1.9 times pre-treatment and 7.5 times after treatment. Fibroblast activation protein (FAP) was overexpressed in the Inflamed_2 and was also overexpressed in the NDRs in both the RISK and GSE16879 datasets. The activation of fibroblasts may play a role in resistance to anti-TNF therapy. Characterizing fibroblasts in inflamed tissues at diagnosis may help to identify patients who are likely to respond to anti-TNF therapy. [ABSTRACT FROM AUTHOR]

Introduction: We explored the long-term evolution of direct healthcare costs for inflammatory bowel diseases (IBD) using a population-level database in a country with an escalating burden of IBD. Methods: We searched the database of the Korean National Health Insurance Claims, which covers more than 97% of the South Korean population. An IBD diagnosis was defined as the combination of a billing code for Crohn's disease (CD: K50.xx) or ulcerative colitis (UC: K51.xx) and at least one claim for IBD-specific drugs. Between 2006 and 2015, a total of 59,447 patients (CD: 17,677; UC: 41,770) were included. Results: The total and mean cost per capita increased significantly over time. In the last year of the study (2015), the cost for anti-tumor necrosis factor (TNF) therapy accounted for 68.8% (CD) and 48.8% (UC) of the total cost. Age at diagnosis (<20 years vs. ≥30 years) and anti-TNF use were independent predictors of increased total IBD cost. Anti-TNF therapy was the strongest predictor of high-cost outliers (designated as the top 20 percentile of the total costs) for IBD (OR: 160.4; 95% CI: 89.0–289.2). The mean cost among patients with newly diagnosed CD increased significantly over the 8-year follow-up period (p =.03), while costs associated with UC remained stable. Only medication costs increased significantly during the follow-up period for CD. Conclusions: Over the past 10 years, the increased usage of anti-TNF agents has been the key driver of IBD-related healthcare costs. Long-term cost-cutting strategies for patients with CD are warranted. [ABSTRACT FROM AUTHOR]

Abstract: Background/aims: The effect of immunosuppressants on the efficacy of a variety of vaccines is a controversial issue in patients with inflammatory bowel disease (IBD). In this study we determined whether specific immunosuppressants impair the serological response to the standard 23-valent pneumococcal polysaccharide vaccine (PPSV23) in a large cohort of patients with Crohn's disease (CD). Methods: This was a multi-center, prospective observational study of adult patients with CD at 15 academic teaching hospitals in Korea. The study population received one intramuscular injection of PPSV23. Anti-pneumococcal IgG antibody titers were measured by immunoassay prior to and 4weeks after vaccination. All vaccination-related adverse events and the effect of the vaccine on disease activity were also evaluated. Results: The overall serological response rate was 67.5% (133/197). The serological response rate was significantly lower in patients on anti-tumor necrosis factor (anti-TNF) therapy (50.0% on anti-TNF alone; 58.0% on anti-TNF combined with an immunomodulator, IM) than patients on 5-aminosalicylate (78.4%; all P-values vs. 5-aminosalicylate<0.05); 45.6% (41/90) of patients on anti-TNF therapy were not protected against PPSV23. IM did not affect the immunologic response to the vaccine. Female gender and anti-TNF therapy were significant predictors of non-response to the vaccine (odds ratio [OR] 2.316, P =0.015; OR 2.582, P =0.048, respectively). Vaccination was generally safe and tolerated by all patients. Conclusions: Patients with CD on anti-TNF therapy are at significant risk of an inadequate response to PPSV23. The pneumococcal vaccination strategy should be optimized for patients with CD on anti-TNF therapy. [Copyright &y& Elsevier]

Background and Aim Although differences in genetic susceptibility and the clinical features of Crohn's disease ( CD) have been reported between Asian and Caucasian patients, the disease course and predictors of CD in Asians remains poorly defined. The study therefore aimed to investigate factors predictive of the clinical outcomes of patients with CD in a Korean population. Methods This retrospective multicenter cohort study included 728 Korean CD patients from 13 university hospitals. The first CD-related surgery or need for immunosuppressive or biological agents were regarded as the clinical outcomes of interest. Results A total of 126 (17.3%) CD patients underwent CD-related surgery, while 473 (65.0%) and 196 (26.9%) were prescribed thiopurine drugs and infliximab, respectively. Multivariate Cox regression analysis identified current (hazard ratio [ HR] = 1.86; P = 0.018) and former smoking habits ( HR = 1.78; P = 0.049), stricturing ( HR = 2.24; P < 0.001), and penetrating disease behavior at diagnosis ( HR = 3.07; P < 0.001) as independent predictors associated with the first CD-related surgery. With respect to immunosuppressive and biological agents, younger age (< 40 years) ( HR = 2.17; P < 0.001 and HR = 2.10; P = 0.006, respectively), ileal involvement ( HR = 1.36; P = 0.035 and HR = 2.17; P = 0.006, respectively), and perianal disease ( HR = 1.42; P = 0.001 and HR = 1.38; P = 0.038, respectively) at diagnosis were significant predictors for the need of these medications. Conclusions In Korean patients with CD, stricturing, penetrating disease behavior, and smoking habits at the time of diagnosis are independent predictors for CD-related surgery. It was also identified that younger age (< 40 years), ileal involvement, and perianal disease at diagnosis are predictive of a need for immunosuppressive or biological agents. [ABSTRACT FROM AUTHOR]

Early intestinal resection in patients with Crohn's disease (CD) is necessary due to a severe and complicating disease course. Herein, we aim to predict which patients with CD need early intestinal resection within 3 years of diagnosis, according to a tree-based machine learning technique. The single-nucleotide polymorphism (SNP) genotype data for 337 CD patients recruited from 15 hospitals were typed using the Korea Biobank Array. For external validation, an additional 126 CD patients were genotyped. The predictive model was trained using the 102 candidate SNPs and seven sets of clinical information (age, sex, cigarette smoking, disease location, disease behavior, upper gastrointestinal involvement, and perianal disease) by employing a tree-based machine learning method (CatBoost). The importance of each feature was measured using the Shapley Additive Explanations (SHAP) model. The final model comprised two clinical parameters (age and disease behavior) and four SNPs (rs28785174, rs60532570, rs13056955, and rs7660164). The combined clinical–genetic model predicted early surgery more accurately than a clinical-only model in both internal (area under the receiver operating characteristic (AUROC), 0.878 vs. 0.782; n = 51; p < 0.001) and external validation (AUROC, 0.836 vs. 0.805; n = 126; p < 0.001). Identification of genetic polymorphisms and clinical features enhanced the prediction of early intestinal resection in patients with CD. [ABSTRACT FROM AUTHOR]