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Intestinal fibrosis is the primary cause of disability in patients with Crohn's disease (CD), yet effective therapeutic strategies are currently lacking. Here, we report a multiomics analysis of gut microbiota and fecal/blood metabolites of 278 CD patients and 28 healthy controls, identifying characteristic alterations in gut microbiota (e.g., Lachnospiraceae, Ruminococcaceae, Muribaculaceae, Saccharimonadales) and metabolites (e.g., L-aspartic acid, glutamine, ethylmethylacetic acid) in moderate-severe intestinal fibrosis. By integrating multiomics data with magnetic resonance enterography features, putative links between microbial metabolites and intestinal fibrosis-associated morphological alterations were established. These potential associations were mediated by specific combinations of amino acids (e.g., L-aspartic acid), primary bile acids, and glutamine. Finally, we provided causal evidence that L-aspartic acid aggravated intestinal fibrosis both in vitro and in vivo. Overall, we offer a biologically plausible explanation for the hypothesis that gut microbiota and its metabolites promote intestinal fibrosis in CD while also identifying potential targets for therapeutic trials., (© 2024. The Author(s).)

Background: A pathogenic mutation in the manganese transporter ZIP8 (A391T; rs13107325) increases the risk of Crohn's disease. ZIP8 regulates manganese homeostasis and given the shared need for metals between the host and resident microbes, there has been significant interest in alterations of the microbiome in carriers of ZIP8 A391T. Prior studies have not examined the ileal microbiome despite associations between ileal disease and ZIP8 A391T., Methods: Here, we used the Pediatric Risk Stratification Study (RISK) cohort to perform a secondary analysis of 16S ribosomal RNA gene sequencing data obtained from ileal and rectal mucosa to study associations between ZIP8 A391T carrier status and microbiota composition., Results: We found sequence variants mapping to Veillonella were decreased in the ileal mucosa of ZIP8 A391T carriers. Prior human studies have demonstrated the sensitivity of Veillonella to bile acid abundance. We therefore hypothesized that bile acid homeostasis is differentially regulated in carriers of ZIP8 A391T. Using a mouse model of ZIP8 A391T, we demonstrate an increase in total bile acids in the liver and stool and decreased fibroblast growth factor 15 (Fgf15) signaling, consistent with our hypothesis. We confirmed dysregulation of FGF19 in the 1000IBD cohort, finding that plasma FGF19 levels are lower in ZIP8 A391T carriers with ileocolonic Crohn's disease., Conclusions: In the search for genotype-specific therapeutic paradigms for patients with Crohn's disease, these data suggest targeting the FGF19 pathway in ZIP8 A391T carriers. Aberrant bile acid metabolism may precede development of Crohn's disease and prioritize study of the interactions between manganese homeostasis, bile acid metabolism and signaling, and complicated ileal Crohn's disease., (© The Author(s) 2024. Published by Oxford University Press on behalf of Crohn’s & Colitis Foundation. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)

Background: Mitochondrial dysfunction has been linked to the development of inflammatory bowel disease (IBD), but the genetic pathophysiology was not fully elucidated. We employed Mendelian randomization and colocalization analyses to investigate the associations between mitochondrial-related genes and IBD via integrating multi-omics., Methods: Summary-level data of mitochondrial gene methylation, expression and protein abundance levels were obtained from corresponding methylation, expression and protein quantitative trait loci studies, respectively. We obtained genetic associations with IBD and its two subtypes from the Inflammatory Bowel Disease Genetics Consortium (discovery), the UK Biobank (replication), and the FinnGen study (replication). We performed summary-data-based Mendelian randomization analysis to assess the associations of mitochondrial gene-related molecular features with IBD. Colocalization analysis was further conducted to assess whether the identified signal pairs shared a causal genetic variant., Findings: After integrating the multi-omics data between mQTL-eQTL and eQTL-pQTL, we identified two mitochondrial genes, i.e., PARK7 and ACADM, with tier 1 evidence for their associations with IBD and ulcerative colitis (UC). PDK1 and FISI genes were associated with UC risk with tier 2 and tier 3 evidence, respectively. The methylation of cg05467918 in ACADM was associated with lower expression of ACADM, which fits with the positive effect of cg05467918 methylation on UC risk. Consistently, the inverse associations between gene methylation and gene expression were also observed in PARK7 (cg10385390) and PDK1 (cg17679246), which were corroborated with the protective role in UC. At circulating protein level, genetically predicted higher levels of PARK7 (OR 0.36, 95% CI 0.25-0.52) and HINT1 (OR 0.47, 95% CI 0.30-0.74) were inversely associated with IBD risk; genetically predicted higher level of HINT1 was associated with a decreased risk of Crohn's disease (CD) (OR 0.26, 95% CI 0.14-0.49) and a higher level of ACADM (OR 0.67, 95% CI 0.55-0.83), PDK1 (OR 0.63, 95% CI 0.49-0.81), FIS1 (OR 0.63, 95% CI 0.47-0.83) was associated with a decreased risk of UC., Interpretation: We found that the mitochondrial PARK7 gene was putatively associated with IBD risk, and mitochondrial FIS1, PDK1, and ACADM genes were associated with UC risk with evidence from multi-omics levels. This study identified mitochondrial genes in relation to IBD, which may enhance the understanding of the pathogenic mechanisms of IBD development., Funding: XL is supported by the Natural Science Fund for Distinguished Young Scholars of Zhejiang Province (LR22H260001) and Healthy Zhejiang One Million People Cohort (K-20230085)., Competing Interests: Declaration of interests The authors declare that they have no competing interests., (Copyright © 2023 The Authors. Published by Elsevier B.V. All rights reserved.)

Background: A distinctive metabolic phenotype provides the opportunity to discover noninvasive biomarkers for the diagnosis of Crohn's disease (CD) and for differentiating it from other intestinal inflammatory diseases. The study sought to identify new biomarkers for CD diagnosis., Methods: Serum metabolites from 68 newly diagnosed and treatment-naïve patients with CD and 56 healthy control (HC) subjects were profiled using targeted liquid chromatography-mass spectrometry. Five metabolic biomarkers were identified to distinguish patients with CD from the HC subjects and validated in a separate cohort consisting of 110 patients with CD and 90 HC subjects using a combination of univariate analysis, orthogonal partial least-squares discriminant analysis, and receiver-operating characteristic curve analysis. Differences in the 5 metabolites were evaluated among patients with CD and patients with ulcerative colitis (n = 62), intestinal tuberculosis (n = 48), and Behçet's disease (n = 31)., Results: Among the 185 quantified metabolites, a panel of 5 (pyruvate, phenylacetylglutamine, isolithocholic acid, taurodeoxycholic acid, and glycolithocholic acid) were found to distinguish patients with CD with high accuracy from HC subjects, with an area under the curve of 0.861 (P < .001). The performance of the model in assessing clinical disease activity was comparable to that of the present biomarkers: C-reactive protein and erythrocyte sedimentation rate. The 5 metabolites were significantly different among the patients and were valuable in the differentiation between CD and other chronic intestinal inflammatory diseases., Conclusions: The combination of 5 serum metabolite biomarkers for the diagnosis of CD has the potential to provide an accurate, noninvasive, and inexpensive alternative to conventional tests and might be valuable for the differentiation from other diagnostically challenging intestinal inflammatory diseases., (© The Author(s) 2023. Published by Oxford University Press on behalf of Crohn’s & Colitis Foundation. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Background: Disrupted intestinal epithelial barrier is one of the major causes of Crohn's disease (CD). Novel molecular targets for intestinal epithelial barrier are essential to treatment of CD. Transmembrane and immunoglobulin domain-containing protein 1 (TMIGD1) is an adhesion molecule that regulates cell adhesion, migration, and enterocyte differentiation. However, the function and mechanism of TMIGD1 in CD and intestinal epithelial barrier has rarely been studied. Furthermore, the association between TMIGD1 and the clinical features of CD remains unclear., Methods: Transcriptome analysis on colonic mucosa from CD patients and healthy individuals were performed to identify dysregulated genes. Multi-omics integration of the 1000IBD cohort including genomics, transcriptomics of intestinal biopsies, and serum proteomics identified the association between genes and characteristics of CD. Inflammation was assessed by cytokine production in cell lines, organoids and intestinal-specific Tmigd1 knockout (Tmigd1 INT-KO ) mice. Epithelial barrier integrity was evaluated by trans-epithelium electrical resistance (TEER), paracellular permeability, and apical junction complex (AJC) expression. Co-immunoprecipitation, GST pull-down assays, mass spectrometry, proteomics, and transcriptome analysis were used to explore downstream mechanisms., Results: Multi-omics integration suggested that TMIGD1 was negatively associated with inflammatory characteristics of CD. TMIGD1 was downregulated in inflamed intestinal mucosa of patients with CD and mice colitis models. Tmigd1 INT-KO mice were more susceptible to chemically induced colitis. In epithelial cell lines and colonic organoids, TMIGD1 knockdown caused impaired intestinal barrier integrity evidenced by increased paracellular permeability and reduced TEER and AJC expression. TMIGD1 knockdown in intestinal epithelial cells also induced pro-inflammatory cytokine production. Mechanistically, TMIGD1 directly interacted with cytoplasmic BAF nuclear assembly factor 1 (BANF1) to inhibit NF-κB activation. Exogenous expression of TMIGD1 and BANF1 restored intestinal barrier function and inhibited inflammation in vitro and in vivo. TMIGD1 expression predicted response to anti-TNF treatment in patients with CD., Conclusions: Our study demonstrated that TMIGD1 maintained intestinal barrier integrity and inactivated inflammation, and was therefore a potential therapeutic target for CD., (© 2023. BioMed Central Ltd., part of Springer Nature.)

Inflammatory bowel diseases (IBDs), e.g., Crohn's disease (CD) and ulcerative colitis (UC), are chronic immune-mediated inflammatory diseases. A comprehensive overview of an IBD-specific antibody epitope repertoire is, however, lacking. Using high-throughput phage-display immunoprecipitation sequencing (PhIP-Seq), we identified antibodies against 344,000 antimicrobial, immune, and food antigens in 497 individuals with IBD compared with 1,326 controls. IBD was characterized by 373 differentially abundant antibody responses (202 overrepresented and 171 underrepresented), with 17% shared by both IBDs, 55% unique to CD, and 28% unique to UC. Antibody reactivities against bacterial flagellins dominated in CD and were associated with ileal involvement, fibrostenotic disease, and anti-Saccharomyces cerevisiae antibody positivity, but not with fecal microbiome composition. Antibody epitope repertoires accurately discriminated CD from controls (area under the curve [AUC] = 0.89), and similar discrimination was achieved when using only ten antibodies (AUC = 0.87). Individuals with IBD thus show a distinct antibody repertoire against selected peptides, allowing clinical stratification and discovery of immunological targets., Competing Interests: Declaration of interests G.D. received an unrestricted research grant from Takeda and speaker fees from Pfizer and Janssen Pharmaceuticals. R.K.W. acted as consultant for Takeda, received unrestricted research grants from Takeda, Johnson & Johnson, Tramedico, and Ferring and received speaker fees from MSD, AbbVie, and Janssen Pharmaceuticals. M.C.V. received speaker fees from Janssen-Cilag, Galapagos, and Ferring B.V., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Background: Oxidative stress (OS) is a key pathophysiological mechanism in Crohn's disease (CD). OS-related genes can be affected by environmental factors, intestinal inflammation, gut microbiota, and epigenetic changes. However, the role of OS as a potential CD etiological factor or triggering factor is unknown, as differentially expressed OS genes in CD can be either a cause or a subsequent change of intestinal inflammation. Herein, we used a multi-omics summary data-based Mendelian randomization (SMR) approach to identify putative causal effects and underlying mechanisms of OS genes in CD., Methods: OS-related genes were extracted from the GeneCards database. Intestinal transcriptome datasets were collected from the Gene Expression Omnibus (GEO) database and meta-analyzed to identify differentially expressed genes (DEGs) related to OS in CD. Integration analyses of the largest CD genome-wide association study (GWAS) summaries with expression quantitative trait loci (eQTLs) and DNA methylation QTLs (mQTLs) from the blood were performed using SMR methods to prioritize putative blood OS genes and their regulatory elements associated with CD risk. Up-to-date intestinal eQTLs and fecal microbial QTLs (mbQTLs) were integrated to uncover potential interactions between host OS gene expression and gut microbiota through SMR and colocalization analysis. Two additional Mendelian randomization (MR) methods were used as sensitivity analyses. Putative results were validated in an independent multi-omics cohort from the First Affiliated Hospital of Sun Yat-sen University (FAH-SYS)., Results: A meta-analysis from six datasets identified 438 OS-related DEGs enriched in intestinal enterocytes in CD from 817 OS-related genes. Five genes from blood tissue were prioritized as candidate CD-causal genes using three-step SMR methods: BAD, SHC1, STAT3, MUC1, and GPX3. Furthermore, SMR analysis also identified five putative intestinal genes, three of which were involved in gene-microbiota interactions through colocalization analysis: MUC1, CD40, and PRKAB1. Validation results showed that 88.79% of DEGs were replicated in the FAH-SYS cohort. Associations between pairs of MUC1-Bacillus aciditolerans and PRKAB1-Escherichia coli in the FAH-SYS cohort were consistent with eQTL-mbQTL colocalization., Conclusions: This multi-omics integration study highlighted that OS genes causal to CD are regulated by DNA methylation and host-microbiota interactions. This provides evidence for future targeted functional research aimed at developing suitable therapeutic interventions and disease prevention., (© 2023. The Author(s).)

Objective: Inflammatory bowel disease (IBD) is not only a chronic inflammatory disorder of the gastrointestinal tract but also accompanied by systemic inflammation. The onset of hypertension is closely related to systemic inflammation. However, the relationship between IBD and hypertension has not been investigated. We aimed to investigate the potential association between IBD and the incidence of hypertension., Method: We retrieved IBD onset and the incidence of hypertension from a public database UK Biobank. The association between the onset of IBD and subsequent incidence of hypertension was analyzed using a multivariate Cox regression analysis, and propensity score matching was performed for sensitivity analysis., Result: Of a total of 281,064 participants included in the study, 2376 (0.8%) were diagnosed with IBD at baseline, and 20,129 (7.2%) in the whole cohort developed hypertension with a median follow-up duration of 8.1 years (interquartile range [IQR] 7.3-8.8 years). Patients with IBD had a higher cumulative risk of hypertension compared with general population (10.9% in ulcerative colitis [UC], 7.7% in Crohn's disease [CD], and 9.3% in IBD unclassified [IBD-U] vs. 7.1% in non-IBD, p < 0.001). Multivariate Cox regression analysis identified that UC, rather than CD or IBD-U, was independently associated with subsequent occurrence of hypertension (HR 1.30, 95% CI: 1.11-1.52, p = 0.001). In propensity matching analysis, UC also showed its robustness as a risk factor for the prediction of hypertension (HR 1.56, 95% CI: 1.21-2.03, p = 0.001)., Conclusion: In IBD patients, UC rather than CD is associated with a higher risk for the incidence of hypertension compared with general population. Close monitoring of hypertension might be required in clinical practice., (© 2022 The Authors. United European Gastroenterology Journal published by Wiley Periodicals LLC on behalf of United European Gastroenterology.)

The pattern-recognition receptor NOD2 senses bacterial muropeptides to regulate host immunity and maintain homeostasis. Loss-of-function mutations in NOD2 are associated with Crohn's disease (CD), but how the variations in microbial factors influence NOD2 signaling and host pathology is elusive. We demonstrate that the Firmicutes peptidoglycan remodeling enzyme, DL-endopeptidase, increased the NOD2 ligand level in the gut and impacted colitis outcomes. Metagenomic analyses of global cohorts (n = 857) revealed that DL-endopeptidase gene abundance decreased globally in CD patients and negatively correlated with colitis. Fecal microbiota from CD patients with low DL-endopeptidase activity predisposed mice to colitis. Administering DL-endopeptidase, but not an active site mutant, alleviated colitis via the NOD2 pathway. Therapeutically restoring NOD2 ligands with a DL-endopeptidase-producing Lactobacillus salivarius strain or mifamurtide, a clinical analog of muramyl dipeptide, exerted potent anti-colitis effects. Our study suggests that the depletion of DL-endopeptidase contributes to CD pathogenesis through NOD2 signaling, providing a therapeutically modifiable target., Competing Interests: Declaration of interests H.W.Z. is listed as an inventor on patents related to the anti-colitis effect of the isolated L. salivarius and mifamurtide., (Copyright © 2022 The Authors. Published by Elsevier Inc. All rights reserved.)

Diet plays an important role in the development and progression of inflammatory bowel disease (IBD, comprising Crohn’s disease (CD) and ulcerative colitis (UC)). However, little is known about the extent to which different diets reflect inflammation in IBD beyond measures such as faecal calprotectin or C-reactive protein. In this study, we aimed to unravel associations between dietary patterns and circulating inflammatory proteins in patients with IBD. Plasma concentrations of 73 different inflammation-related proteins were measured in 454 patients with IBD by proximity extension assay (PEA) technology. Food frequency questionnaires (FFQ) were used to assess habitual diet. Principal component analysis (PCA) was performed to extract data-driven dietary patterns. To identify associations between dietary patterns and plasma proteins, we used general linear models adjusting for age, sex, BMI, plasma storage time, smoking, surgical history and medication use. Stratified analyses were performed for IBD type, disease activity and protein intake. A high-sugar diet was strongly inversely associated with fibroblast growth factor-19 (FGF-19) independent of IBD type, disease activity, surgical history and deviance from recommended protein intake (false discovery rate (FDR) < 0.05). Conversely, a Mediterranean-style pattern was associated with higher FGF-19 levels (FDR < 0.05). A pattern characterised by high alcohol and coffee intake was positively associated with CCL11 (eotaxin-1) levels and with lower levels of IL-12B (FDR < 0.05). All results were replicated in CD, whereas only the association with FGF-19 was significant in UC. Our study suggests that dietary habits influence distinct circulating inflammatory proteins implicated in IBD and supports the pro- and anti-inflammatory role of diet. Longitudinal measurements of inflammatory markers, also postprandial, are needed to further elucidate the diet−inflammation relationship.

Background & Aims: Pro-inflammatory diet interacting with gut microbiome might trigger for Crohn's disease (CD). We aimed to investigate the relationship between dietary inflammatory potential and microflora/metabolites change and their link with CD., Methods: The dietary inflammatory potential was assessed using a dietary inflammatory index (DII) based on the Food Frequency Questionnaire from 150 new-onset CD patients and 285 healthy controls (HCs). We selected 41 CD patients and 89 HCs who had not received medication for metagenomic and targeted metabolomic sequencing to profile their gut microbial composition as well as fecal and serum metabolites. DII scores were classified into quartiles to investigate associations among different variables., Results: DII scores of CD patients were significantly higher than HCs (0.56 ± 1.20 vs 0.23 ± 1.02, p = 0.017). With adjustment for confounders, a higher DII score was significantly associated with higher risk of CD (OR: 1.420; 95% CI: 1.049, 1.923, p = 0.023). DII score also was positively correlated with disease activity (p = 0.001). Morganella morganii and Veillonella parvula were increased while Coprococcus eutactus was decreased in the pro-inflammatory diets group, as well as in CD. DII-related bacteria were associated with disease activity and inflammatory markers in CD patients. Among the metabolic change, pro-inflammatory diet induced metabolites change were largely involved in amino acid metabolic pathways that were also observed in CD., Conclusions: Pro-inflammatory diet might be associated with increased risk and disease activity of CD. Diet with high DII potentially involves in CD by mediating alterations in gut microbiota and metabolites., Competing Interests: Conflict of Interest All authors declared to have no conflict of interests in this manuscript., (Copyright © 2022 The Author(s). Published by Elsevier Ltd.. All rights reserved.)