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Background: Bismuth quadruple therapies (BQTs) including bismuth, a proton pump inhibitor (PPI) and two antibiotics have been shown to be highly effective for treating Helicobacter pylori infection even in areas of high bacterial antibiotic resistance., Objective: To describe the time trends of use, effectiveness and safety of BQT in Europe using the European Registry on Helicobacter pylori Management (Hp-EuReg)., Design: Patients registered in the Hp-EuReg from 2013 to 2021 who had received BQT were included. The regimens prescribed, the number of eradication attempts, effectiveness, adherence and safety were analysed. The effectiveness was assessed by modified intention to treat (mITT). Time-trend and multivariate analyses were performed to determine variables that predicted treatment success., Results: Of the 49 690 patients included in the Hp-EuReg, 15 582 (31%) had received BQT. BQT use increased from 8.6% of all treatments in 2013 to 39% in 2021. Single-capsule BQT-containing bismuth, metronidazole and tetracycline-plus a PPI (single-capsule BQT, ScBQT) was the most frequent treatment mode (43%). Schemes that obtained an effectiveness above 90% were the 10-day ScBQT and 14-day BQT using tetracycline plus metronidazole, or amoxicillin plus either clarithromycin or metronidazole. Only ScBQT achieved above 90% cure rates in all the geographical areas studied. Using the ScBQT scheme, adherence, the use of standard or high-dose PPIs, 14-day prescriptions and the use of BQT as first-line treatment were significantly associated with higher mITT effectiveness., Conclusion: The use of BQT increased notably in Europe over the study period. A 10-day ScBQT was the scheme that most consistently achieved optimal effectiveness., Trial Registration Number: NCT02328131., Competing Interests: Competing interests: XC has received research grants and fees for lectures from Allergan. JPG has served as speaker, consultant and advisory member for or has received research funding from Mayoly Spindler, Allergan, Diasorin, Richen, Biocodex and Juvisé. OPN received research funding from Allergan, Mayoly Spindler, Richen, Biocodex and Juvisé. DSB served as a lecturer for Astellas, AstraZeneca, KRKA and Abbott. FM is a consultant for PHATHOM, DaVoltera and has received grants from Allergan, bioMerieux and Mobidiag. The remaining authors declare no conflict of interest., (© Author(s) (or their employer(s)) 2024. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

The absolute number of annual cases of gastric cancer in Europe is rising. The Council of the European Union has recommended implementation of gastric cancer screening for countries or regions with a high gastric cancer incidence and death rates. However, as of 2024 no organised gastric cancer screening programme has been launched in Europe.There are several ways to decrease gastric cancer burden, but the screen and treat strategy for Helicobacter pylori (H. pylori ) seems to be the most appropriate for Europe. It has to be noted that increased use of antibiotics would be associated with this strategy.Only organised population-based cancer screening is recommended in the European Union, therefore gastric cancer screening also is expected to fulfil the criteria of an organised screening programme. In this respect, several aspects of screening organisation need to be considered before full implementation of gastric cancer prevention in Europe; the age range of the target group, test types, H. pylori eradication regimens and surveillance strategies are among them. Currently, ongoing projects (GISTAR, EUROHELICAN, TOGAS and EUCanScreen) are expected to provide the missing evidence. Feedback from the decision-makers and the potential target groups, including vulnerable populations, will be important to planning the programme.This paper provides an overview of the recent decisions of the European authorities, the progress towards gastric cancer implementation in Europe and expected challenges. Finally, a potential algorithm for gastric cancer screening in Europe is proposed., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2024. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Objective: Achieving HBV cure will require novel combination therapies of direct-acting antivirals and immunomodulatory agents. In this context, the toll-like receptor 8 (TLR8) agonist selgantolimod (SLGN) has been investigated in preclinical models and clinical trials for chronic hepatitis B (CHB). However, little is known regarding its action on immune effectors within the liver. Our aim was to characterise the transcriptomic changes and intercellular communication events induced by SLGN in the hepatic microenvironment., Design: We identified TLR8 -expressing cell types in the human liver using publicly available single-cell RNA-seq data and established a method to isolate Kupffer cells (KCs). We characterised transcriptomic and cytokine KC profiles in response to SLGN. SLGN's indirect effect was evaluated by RNA-seq in hepatocytes treated with SLGN-conditioned media (CM) and quantification of HBV parameters following infection. Pathways mediating SLGN's effect were validated using transcriptomic data from HBV-infected patients., Results: Hepatic TLR8 expression takes place in the myeloid compartment. SLGN treatment of KCs upregulated monocyte markers (eg, S100A12 ) and downregulated genes associated with the KC identity (eg, SPIC ). Treatment of hepatocytes with SLGN-CM downregulated NTCP and impaired HBV entry. Cotreatment with an interleukin 6-neutralising antibody reverted the HBV entry inhibition., Conclusion: Our transcriptomic characterisation of SLGN sheds light into the programmes regulating KC activation. Furthermore, in addition to its previously described effect on established HBV infection and adaptive immunity, we show that SLGN impairs HBV entry. Altogether, SLGN may contribute through KCs to remodelling the intrahepatic immune microenvironment and may thus represent an important component of future combinations to cure HBV infection., Competing Interests: Competing interests: FZ and BT received grants from Assembly, Beam Therapeutics, Blue Jay and JnJ; FZ had consulting activities with Assembly, Blue Jay and GSK. YCH receives grants from Gilead Sciences and Sysmex. FZ is an associate editor of the journal. SD, LL, NK, JJW, AHL, and SPF are or were employees of Gilead Sc., (© Author(s) (or their employer(s)) 2024. Re-use permitted under CC BY. Published by BMJ.)

Objective: In patients with Crohn's disease (CD) on combination therapy (infliximab and immunosuppressant) and stopping infliximab (cohort from the study of infliximab diSconTinuation in CrOhn's disease patients in stable Remission on combined therapy with Immunosuppressors (STORI)), the risk of short-term (≤6 months) and mid/long-term relapse (>6 months) was associated with distinct blood protein profiles. Our aim was to test the external validity of this finding in the SPARE cohort (A proSpective Randomized Controlled Trial comParing infliximAb-antimetabolites Combination Therapy to Anti-metabolites monotheRapy and Infliximab monothErapy in Crohn's Disease Patients in Sustained Steroid-free Remission on Combination Therapy)., Design: In SPARE, patients with CD in sustained steroid-free clinical remission and on combination therapy were randomly allocated to three arms: continuing combination therapy, stopping infliximab or stopping immunosuppressant. In the baseline serum of the STORI and SPARE (arm stopping infliximab) cohorts, we studied 202 immune-related proteins. The proteins associated with time to relapse (univariable Cox model) were compared between STORI and SPARE. The discriminative ability of biomarkers (individually and combined in pairs) was evaluated by the c-statistic (concordance analysis) which was compared with C-reactive protein (CRP), faecal calprotectin and a previously validated model (CEASE)., Results: In STORI and SPARE, distinct blood protein profiles were associated with the risk of short-term (eg, high level: CRP, haptoglobin, interleukin-6, C-type lectin domain family 4 member C) and mid/long-term relapse (eg, low level: Fms-related tyrosine kinase 3 ligand, kallistatin, fibroblast growth factor 2). At external validation, the top 10 biomarker pairs showed a higher c-statistic than the CEASE model, CRP and faecal calprotectin in predicting short-term (0.76-0.80 vs 0.74 vs 0.71 vs 0.69, respectively) and mid/long-term relapse (0.66-0.68 vs 0.61 vs 0.52 vs 0.59, respectively)., Conclusion: In patients with CD stopping infliximab, we confirm that the risk of short-term and mid/long-term relapse is associated with distinct blood protein profiles showing the potential to guide infliximab withdrawal., Trial Registration Number: NCT00571337 and NCT02177071., Competing Interests: Competing interests: PB has received research grants from AbbVie, Amgen, Celltrion, Mylan, Pfizer and Takeda; lecture fees from AbbVie, Celltrion, Janssen, Lilly and Takeda; and consulting fees from AbbVie, Arena Pharmaceuticals, Bristol Myers Squibb, Celltrion, Dr Falk Pharma, Galapagos, Janssen, Lilly, Pentax, PSI-CRO, Roche, Takeda and Tetrameros. LV has received fees from AbbVie, Amgen, Biogen, Mylan, Takeda, MSD, Janssen, Pfizer, Ferring and Galapagos. SV has received speaker’s fees from AbbVie, Ferring, Janssen and Takeda. J-FC has received grants from AbbVie, Janssen Pharmaceuticals, Prometheus, Takeda and Bristol Myers Squibb; receiving payment for lectures from AbbVie, and Takeda; receiving consulting fees from AbbVie, Amgen, AnaptysBio, Allergan, Arena Pharmaceuticals, Boehringer Ingelheim, Bristol Myers Squibb, Celgene Corporation, Celltrion, Eli Lilly, Ferring Pharmaceuticals, Galmed Research, Glaxo Smith Kline, Genentech (Roche), Janssen Pharmaceuticals, Kaleido Biosciences, Immunic, Invea, Iterative Scopes, Merck, Landos, Microba Life Science, Novartis, Otsuka Pharmaceutical, Pfizer, Protagonist Therapeutics, Prometheus, Sanofi, Seres, Takeda, Teva, TiGenix, Vifor; and hold stock options in Intestinal Biotech Development. EL has received educational and research grants from Janssen, Pfizer, AbbVie and Takeda, Fresenius-Kabi; speaker fees from AbbVie, Dr Falk Pharma, Ferring, Janssen, Pfizer, Celgene, Bristol Myers Squibb (BMS), Galapagos and Takeda; advisory board fees for AbbVie, Celgene, Ferring, Janssen, BMS, Pfizer, Takeda, Gilead-Galapagos, Arena and Elli Lilly; and consultancy fees from AbbVie., (© Author(s) (or their employer(s)) 2024. No commercial re-use. See rights and permissions. Published by BMJ.)

Competing Interests: Competing interests: None declared.

Competing Interests: Competing interests: None declared.

Background and Aim: Randomised trials show improved polyp detection with computer-aided detection (CADe), mostly of small lesions. However, operator and selection bias may affect CADe's true benefit. Clinical outcomes of increased detection have not yet been fully elucidated., Methods: In this multicentre trial, CADe combining convolutional and recurrent neural networks was used for polyp detection. Blinded endoscopists were monitored in real time by a second observer with CADe access. CADe detections prompted reinspection. Adenoma detection rates (ADR) and polyp detection rates were measured prestudy and poststudy. Histological assessments were done by independent histopathologists. The primary outcome compared polyp detection between endoscopists and CADe., Results: In 946 patients (51.9% male, mean age 64), a total of 2141 polyps were identified, including 989 adenomas. CADe was not superior to human polyp detection (sensitivity 94.6% vs 96.0%) but outperformed them when restricted to adenomas. Unblinding led to an additional yield of 86 true positive polyp detections (1.1% ADR increase per patient; 73.8% were <5 mm). CADe also increased non-neoplastic polyp detection by an absolute value of 4.9% of the cases (1.8% increase of entire polyp load). Procedure time increased with 6.6±6.5 min (+42.6%). In 22/946 patients, the additional detection of adenomas changed surveillance intervals (2.3%), mostly by increasing the number of small adenomas beyond the cut-off., Conclusion: Even if CADe appears to be slightly more sensitive than human endoscopists, the additional gain in ADR was minimal and follow-up intervals rarely changed. Additional inspection of non-neoplastic lesions was increased, adding to the inspection and/or polypectomy workload., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2024. No commercial re-use. See rights and permissions. Published by BMJ.)

Objective: Extracellular matrix protein 1 (ECM1) serves as a gatekeeper of hepatic fibrosis by maintaining transforming growth factor-β1 (TGF-β1) in its latent form. ECM1 knockout (KO) causes latent (L) TGF-β1 activation, resulting in hepatic fibrosis with rapid mortality. In chronic liver disease (CLD), ECM1 decreases with increasing CLD severity. We investigate the regulatory role of ECM1 in TGF-β1 bioavailability and its impact on CLD progression., Design: RNAseq was performed to analyse hepatic gene expression. Functional assays were performed using hepatic stellate cells (HSCs), Ecm1 -KO and Fxr -KO mice, patient liver tissue and computer simulations., Results: Expression of LTGF-β1 activators, including thrombospondins (TSPs), ADAMTS proteases and matrix metalloproteinases (MMPs), increased along with profibrotic gene expression in liver tissue of Ecm1 -KO mice. In HSCs, overexpression of ECM1 prevented LTGF-β1 activation mediated by TSP-1, ADAMTS1, and MMP-2/9. In vitro interaction assays demonstrated that ECM1 inhibited LTGF-β1 activation by interacting with TSP-1 and ADAMTS1 via their respective, intrinsic KRFK or KTFR amino acid sequences and by suppressing MMP-2/9 proteolytic activity. In mice, ECM1 overexpression attenuated KRFK-induced LTGF-β1 activation while KTFR treatment reversed Ecm1 -KO-mediated and Fxr -KO-mediated liver injury. In patients with CLD, ECM1 expression was inversely correlated with TSP-1, ADAMTS1, MMP-2/9 expression and LTGF-β1 activation. And, these results were complemented by a computational compartment model representing the key network of cellular phenotypes and predicted interactions in liver fibrogenesis., Conclusion: Our findings underscore the hepatoprotective effect of ECM1, which interferes with mediators of LTGF-β1 activation, suggesting ECM1 or its representative peptide as potential antifibrotic therapies in CLD., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2024. No commercial re-use. See rights and permissions. Published by BMJ.)

Artificial intelligence (AI) holds significant potential for enhancing quality of gastrointestinal (GI) endoscopy, but the adoption of AI in clinical practice is hampered by the lack of rigorous standardisation and development methodology ensuring generalisability. The aim of the Quality Assessment of pre-clinical AI studies in Diagnostic Endoscopy (QUAIDE) Explanation and Checklist was to develop recommendations for standardised design and reporting of preclinical AI studies in GI endoscopy.The recommendations were developed based on a formal consensus approach with an international multidisciplinary panel of 32 experts among endoscopists and computer scientists. The Delphi methodology was employed to achieve consensus on statements, with a predetermined threshold of 80% agreement. A maximum three rounds of voting were permitted.Consensus was reached on 18 key recommendations, covering 6 key domains: data acquisition and annotation (6 statements), outcome reporting (3 statements), experimental setup and algorithm architecture (4 statements) and result presentation and interpretation (5 statements). QUAIDE provides recommendations on how to properly design (1. Methods, statements 1-14), present results (2. Results, statements 15-16) and integrate and interpret the obtained results (3. Discussion, statements 17-18).The QUAIDE framework offers practical guidance for authors, readers, editors and reviewers involved in AI preclinical studies in GI endoscopy, aiming at improving design and reporting, thereby promoting research standardisation and accelerating the translation of AI innovations into clinical practice., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2024. No commercial re-use. See rights and permissions. Published by BMJ.)

Background: Endoscopic retrograde cholangiopancreatography (ERCP) with fully covered self-expandable metal stent (FCSEMS) placement is the preferred approach for biliary drainage in patients with suspected distal malignant biliary obstruction (MBO). However, FCSEMS placement is associated with a high risk of post-ERCP pancreatitis (PEP). Endoscopic sphincterotomy prior to FCSEMS placement may reduce PEP risk., Objective: To compare endoscopic sphincterotomy to no sphincterotomy prior to FCSEMS placement., Design: This multicentre, randomised, superiority trial was conducted in 17 hospitals and included patients with suspected distal MBO. Patients were randomised during ERCP to receive either endoscopic sphincterotomy (sphincterotomy group) or no sphincterotomy (control group) prior to FCSEMS placement. The primary outcome was PEP within 30 days. Secondary outcomes included procedure-related complications and 30-day mortality. An interim analysis was performed after 50% of patients (n=259) had completed follow-up., Results: Between May 2016 and June 2023, 297 patients were included in the intention-to-treat analysis, with 156 in the sphincterotomy group and 141 in the control group. After the interim analysis, the study was terminated prematurely due to futility. PEP did not differ between groups, occurring in 26 patients (17%) in the sphincterotomy group compared with 30 patients (21%) in the control group (relative risk 0.78, 95% CI 0.49 to 1.26, p=0.37). There were no significant differences in bleeding, perforation, cholangitis, cholecystitis or 30-day mortality., Conclusion: This trial found that endoscopic sphincterotomy was not superior to no sphincterotomy in reducing PEP in patients with distal MBO. Therefore, there was insufficient evidence to recommend routine endoscopic sphincterotomy prior to FCEMS placement., Trial Registration Number: NL5130., Competing Interests: Competing interests: JvH has received research support from Cook Medical and acted as lecturer for Cook Medical, Boston Scientific and Falk, and as consultant for Olympus, outside the submitted work. RPV received a research grant and acted as consultant for Boston Scientific, outside the submitted work. PF acted as a consultant for Cook Endoscopy and Olympus, outside the submitted work. RvW acted as a consultant for Boston Scientific, outside the submitted work. All other authors declare that they have no competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© Author(s) (or their employer(s)) 2024. No commercial re-use. See rights and permissions. Published by BMJ.)

Background and Aims: Conventional hot snare endoscopic mucosal resection (H-EMR) is effective for the management of large (≥20 mm) non-pedunculated colon polyps (LNPCPs) however, electrocautery-related complications may incur significant morbidity. With a superior safety profile, cold snare EMR (C-EMR) of LNPCPs is an attractive alternative however evidence is lacking. We conducted a randomised trial to compare the efficacy and safety of C-EMR to H-EMR., Methods: Flat, 15-50 mm adenomatous LNPCPs were prospectively enrolled and randomly assigned to C-EMR or H-EMR with margin thermal ablation at a single tertiary centre. The primary outcome was endoscopically visible and/or histologically confirmed recurrence at 6 months surveillance colonoscopy. Secondary outcomes were clinically significant post-EMR bleeding (CSPEB), delayed perforation and technical success., Results: 177 LNPCPs in 177 patients were randomised to C-EMR arm (n=87) or H-EMR (n=90). Treatment groups were equivalent for technical success 86/87 (98.9%) C-EMR versus H-EMR 90/90 (100%); p=0.31. Recurrence was significantly greater in C-EMR (16/87, 18.4% vs 1/90, 1.1%; relative risk (RR) 16.6, 95% CI 2.24 to 122; p<0.001).Delayed perforation (1/90 (1.1%) vs 0; p=0.32) only occurred in the H-EMR group. CSPEB was significantly greater in the H-EMR arm (7/90 (7.8%) vs 1/87 (1.1%); RR 6.77, 95% CI 0.85 to 53.9; p=0.034)., Conclusion: Compared with H-EMR, C-EMR for flat, adenomatous LNPCPs, demonstrates superior safety with equivalent technical success. However, endoscopic recurrence is significantly greater for cold snare resection and is currently a limitation of the technique., Trial Registration Number: NCT04138030., Competing Interests: Competing interests: MJB: Research Support: Olympus Medical, Cook Medical, Boston Scientific. The remaining authors have no financial, professional or personal conflicts of interest to disclose., (© Author(s) (or their employer(s)) 2024. No commercial re-use. See rights and permissions. Published by BMJ.)

Competing Interests: Competing interests: None declared.

Introduction: The environmental impact of endoscopy is a topic of growing interest. This study aimed to compare the carbon footprint of performing an esogastroduodenoscopy (EGD) with a reusable (RU) or with a single-use (SU) disposable gastroscope., Methods: SU (Ambu aScope Gastro) and RU gastroscopes (Olympus, H190) were evaluated using life cycle assessment methodology (ISO 14040) including the manufacture, distribution, usage, reprocessing and disposal of the endoscope. Data were obtained from Edouard Herriot Hospital (Lyon, France) from April 2023 to February 2024. Primary outcome was the carbon footprint (measured in Kg CO 2 equivalent) for both gastroscopes per examination. Secondary outcomes included other environmental impacts. A sensitivity analysis was performed to examine the impact of varying scenarios., Results: Carbon footprint of SU and RU gastroscopes were 10.9 kg CO 2 eq and 4.7 kg CO 2 eq, respectively. The difference in carbon footprint equals one conventional car drive of 28 km or 6 days of CO 2 emission of an average European household. Based on environmentally-extended input-output life cycle assessment, the estimated per-use carbon footprint of the endoscope stack and washer was 0.18 kg CO 2 eq in SU strategy versus 0.56 kg CO 2 eq in RU strategy. According to secondary outcomes, fossil eq depletion was 130 MJ (SU) and 60.9 MJ (RU) and water depletion for 6.2 m 3 (SU) and 9.5 m 3 (RU), respectively., Conclusion: For one examination, SU gastroscope have a 2.5 times higher carbon footprint than RU ones. These data will help with the logistics and planning of an endoscopic service in relation to other economic and environmental factors., Competing Interests: Competing interests: ERdS: Olympus Educational activity and advisory work, Apollo Endosurgery Educational activity, Norgine Conference fees and educational activity, Casen Conference fees. MP: Consultant for Olympus, trainer for Olympus, Pentax, Norgine, Boston, Cook. Other authors have nothing to disclose., (© Author(s) (or their employer(s)) 2024. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Background: Statins have multiple benefits in patients with metabolic-associated steatotic liver disease (MASLD)., Aim: To explore the effects of statins on the long-term risk of all-cause mortality, liver-related clinical events (LREs) and liver stiffness progression in patients with MASLD., Methods: This cohort study collected data on patients with MASLD undergoing at least two vibration-controlled transient elastography examinations at 16 tertiary referral centres. Cox regression analysis was performed to examine the association between statin usage and long-term risk of all-cause mortality and LREs stratified by compensated advanced chronic liver disease (cACLD): baseline liver stiffness measurement (LSM) of ≥10 kPa. Liver stiffness progression was defined as an LSM increase of ≥20% for cACLD and from <10 kPa to ≥10 or LSM for non-cACLD. Liver stiffness regression was defined as LSM reduction from ≥10 kPa to <10 or LSM decrease of ≥20% for cACLD., Results: We followed up 7988 patients with baseline LSM 5.9 kPa (IQR 4.6-8.2) for a median of 4.6 years. At baseline, 40.5% of patients used statins, and cACLD was present in 17%. Statin usage was significantly associated with a lower risk of all-cause mortality (adjusted HR=0.233; 95% CI 0.127 to 0.426) and LREs (adjusted HR=0.380; 95% CI 0.268 to 0.539). Statin usage was also associated with lower liver stiffness progression rates in cACLD (HR=0.542; 95% CI 0.389 to 0.755) and non-cACLD (adjusted HR=0.450; 95% CI 0.342 to 0.592), but not with liver stiffness regression (adjusted HR=0.914; 95% CI 0.778 to 1.074)., Conclusions: Statin usage was associated with a relatively lower long-term risk of all-cause mortality, LREs and liver stiffness progression in patients with MASLD., Competing Interests: Competing interests: TC-FY reported serving as an advisory committee member and a speaker for Gilead Sciences outside the submitted work. EAT reported receiving personal fees as advisory board member for Boehringer, Novo Nordisk, Pfizer and Siemens; receiving speaker fees from Echosens, Novo Nordisk and AbbVie outside the submitted work. HH reported personal fees from AstraZeneca, personal fees from Bristol Myers-Squibb, personal fees from MSD, personal fees from Novo Nordisk, personal fees from Boehringer Ingelheim, personal fees from KOWA and personal fees from GW Phara outside the submitted work, and grants from AstraZeneca, grants from Echosens, grants from Gilead Sciences, grants from Intercept, grants from MSD, grants from Novo Nordisk and grants from Pfizer outside the submitted work. JB reported receiving grants and personal fees from Echosens outside the submitted work. JLC reported receiving other from Echosens Clinical Trials during the conduct of the study; grants from Roche Pharma and other from Gilead Advisory Board outside the submitted work. WKC reported serving as consultant or advisory board member for Zuellig Pharma, Abbott, Roche, AbbVie, Boehringer Ingelheim and Novo Nordisk; and a speaker for Novo Nordisk, Abbott, Echosens, Viatris and Hisky Medical. AJS reported receiving grants from Intercept, personal consulting fees from Gilead, grants from Merck, personal consulting fees from Pfizer, grants and personal consulting fees from Eli Lilly, grants and personal consulting fees from Novo Nordisk, Boehringer Ingelheim, Novartis, Histoindex, and stock options from Genfit, Tiziana, Durect, Inversago and personal consulting fees from Genentech, ALnylam, Regeneron, Zydus, LG chem, Hanmi, Madrigal, Path AI, 89 Bio and stock options from Galmed outside the submitted work. VdL reported receiving non-financial support from Echosens during the conduct of the study. PNN reported receiving grants from Novo Nordisk, advisory board and personal consulting fees, honoraria for lectures and travel expenses from Novo Nordisk, personal consulting and advisory board fees from Boehringer Ingelheim, Gilead, Intercept, Poxel Pharmaceuticals, Bristol-Myers Squibb, Pfizer, MSD, Sun Pharma, Eli Lilly, Madrigal, GSK and non-financial support for educational events from AiCME outside the submitted work. LC reported receiving personal fees for consulting and speakers bureau from Echosens during the conduct of the study; personal consultancy fees from Boston pharmaceutical and Gilead, speaker bureau and consultancy personal fees from GSK, personal speaker bureau fees from Inventiva, personal consultancy fees from Madrigal, personal Consultancy fees from MSD and Novo Nordisk, personal consultancy fees from Pfizer, Sagimet and Siemens Healthineers outside the submitted work. CF reported being in the full-time employment of Echosens during the conduct of the study. GL-HW reported receiving personal fees from Echosens during the conduct of the study; grants from Gilead Sciences Research outside the submitted work. MS-WC reported being in the full-time employment of Echosens during the conduct of the study. MR-G reported receiving personal fees from Echosens outside the submitted work. SUK reported personal fees from Gilead Sciences, personal fees from GSK, personal fees from Bayer, personal fees from Eisai, personal fees from AbbVie, personal fees from Echosens, personal fees from MSD, personal fees from Bristol-Myers Squibb and personal fees from AstraZeneca outside the submitted work, and grants from AbbVie, grants from Bristol-Myers Squibb, and grants from Gilead Sciences outside the submitted work. VW-SW reported receiving personal speaker fees from Abbott, consultant and speaker fees from AbbVie, personal consultant fees from Boehringer Ingelheim, Echosens, Gilead Sciences, grants from Gilead Sciences, personal consultant fees from Intercept, Inventiva, Novo Nordisk, personal consultant fees from Pfizer, Sagimet Biosciences, TARGET PharmaSolutions, personal speaker fees from Unilab, personal consultant fees from Visirna, and being a cofounder of Illuminatio outside the submitted work. CDB has received grant support from Echosens. No other disclosures were reported., (© Author(s) (or their employer(s)) 2024. No commercial re-use. See rights and permissions. Published by BMJ.)

Objective: Pancreatic ductal adenocarcinoma (PDAC) is a highly lethal malignancy because it is often diagnosed at a late-stage. Signal transducer and activator of transcription 5 (STAT5) is a transcription factor implicated in the progression of various cancer types. However, its role in KRAS-driven pancreatic tumourigenesis remains unclear., Design: We performed studies with LSL-Kras G12D ; Ptf1a-Cre ERT (KC ERT ) mice or LSL-Kras G12D (KPC) mice crossed with conditional disruption of STAT5 or completed deficiency interleukin (IL)-22. Pancreatitis was induced in mice by administration of cerulein. Pharmacological inhibition of STAT5 on PDAC prevention was studied in the orthotopic transplantation and patient-derived xenografts PDAC model, and KPC mice.LSL-Trp53 R172H ; Pdx1-Cre (KPC) mice crossed with conditional disruption of STAT5 or completed deficiency interleukin (IL)-22. Pancreatitis was induced in mice by administration of cerulein. Pharmacological inhibition of STAT5 on PDAC prevention was studied in the orthotopic transplantation and patient-derived xenografts PDAC model, and KPC mice., Results: The expression and phosphorylation of STAT5 were higher in human PDAC samples than control samples and high levels of STAT5 in tumour cells were associated with a poorer prognosis. The loss of STAT5 in pancreatic cells substantially reduces the KRAS mutation and pancreatitis-derived acinar-to-ductal metaplasia (ADM) and PDAC lesions. Mechanistically, we discovered that STAT5 binds directly to the promoters of ADM mediators, hepatocyte nuclear factor (HNF) 1β and HNF4α. Furthermore, STAT5 plays a crucial role in maintaining energy metabolism in tumour cells during PDAC progression. IL-22 signalling induced by chronic inflammation enhances KRAS-mutant-mediated STAT5 phosphorylation. Deficiency of IL-22 signalling slowed the progression of PDAC and ablated STAT5 activation., Conclusion: Collectively, our findings identified pancreatic STAT5 activation as a key downstream effector of oncogenic KRAS signalling that is critical for ADM initiation and PDAC progression, highlighting its potential therapeutic vulnerability., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2024. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

The gut microbiome has been recognised as a key component in the pathogenesis of inflammatory bowel diseases (IBD), and the wide range of metabolites produced by gut bacteria are an important mechanism by which the human microbiome interacts with host immunity or host metabolism. High-throughput metabolomic profiling and novel computational approaches now allow for comprehensive assessment of thousands of metabolites in diverse biomaterials, including faecal samples. Several groups of metabolites, including short-chain fatty acids, tryptophan metabolites and bile acids, have been associated with IBD. In this Recent Advances article, we describe the contribution of metabolomics research to the field of IBD, with a focus on faecal metabolomics. We discuss the latest findings on the significance of these metabolites for IBD prognosis and therapeutic interventions and offer insights into the future directions of metabolomics research., Competing Interests: Competing interests: RKW acted as consultant for Takeda Pharmaceuticals, received unrestricted research grants from Takeda, Johnson & Johnson, Tramedico and Ferring and received speaker’s fees from MSD, Abbvie and Janssen Pharmaceuticals. All other authors have no conflicts of interest to declare., (© Author(s) (or their employer(s)) 2024. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Competing Interests: Competing interests: None declared.

Background and Aims: The efficacy of colorectal endoscopic mucosal resection (EMR) is limited by recurrence and the necessity for conservative surveillance. Margin thermal ablation (MTA) after EMR has reduced the incidence of recurrence at the first surveillance colonoscopy at 6 months (SC1). Whether this effect is durable to second surveillance colonoscopy (SC2) is unknown. We evaluated long-term surveillance outcomes in a cohort of LNPCPs that have undergone MTA., Methods: LNPCPs undergoing EMR and MTA from four academic endoscopy centres were prospectively recruited. EMR scars were evaluated at SC1 and in the absence of recurrence, SC2 colonoscopy was conducted in a further 12 months. A historical control arm was generated from LNPCPs that underwent EMR without MTA. The primary outcome was recurrence at SC2 in all LNPCPs with a recurrence-free scar at SC1., Results: 1152 LNPCPs underwent EMR with complete MTA over 90 months until October 2022. 854 LNPCPs underwent SC1 with 29/854 (3.4%) LNPCPs demonstrating recurrence. 472 LNPCPs free of recurrence at SC1 underwent SC2. 260 LNPCPs with complete SC2 follow-up formed the control arm from January 2012 to May 2016. Recurrence at SC2 was significantly less in the MTA arm versus controls (1/472 (0.2%) vs 9/260 (3.5%); p<0.001))., Conclusion: LNPCPs that have undergone successful EMR with MTA and are free of recurrence at SC1 are unlikely to develop recurrence in subsequent surveillance out to 2 years. Provided the colon is cleared of synchronous neoplasia, the next surveillance can be potentially extended to 3-5 years. Such an approach would reduce costs and enhance patient compliance., Competing Interests: Competing interests: MJB: Research Support: Olympus Medical, Cook Medical, Boston Scientific. GB: Research Support: Olympus Medical. The remaining authors have no financial, professional, or personal conflicts of interest to disclose., (© Author(s) (or their employer(s)) 2024. No commercial re-use. See rights and permissions. Published by BMJ.)

Background: Cholangiocarcinoma (CCA) is a very difficult-to-treat cancer. Chemotherapies are little effective and response to immune checkpoint inhibitors is limited. Therefore, new therapeutic strategies need to be identified., Objective: We characterised the enzyme protein arginine-methyltransferase 5 (PRMT5) as a novel therapeutic target in CCA., Design: We evaluated the expression of PRMT5, its functional partner MEP50 and methylthioadenosine phosphorylase (MTAP)-an enzyme that modulates the sensitivity of PRMT5 to pharmacological inhibitors-in human CCA tissues. PRMT5-targeting drugs, currently tested in clinical trials for other malignancies, were assessed in human CCA cell lines and organoids, as well as in two immunocompetent CCA mouse models. Transcriptomic, proteomic and functional analyses were performed to explore the underlying antitumoural mechanisms., Results: PRMT5 and MEP50 proteins were correlatively overexpressed in most CCA tissues. MTAP was absent in 25% of intrahepatic CCA. PRMT5-targeting drugs markedly inhibited CCA cell proliferation, synergising with cisplatin and gemcitabine and hindered the growth of cholangiocarcinoma organoids. PRMT5 inhibition blunted the expression of oncogenic genes involved in chromatin remodelling and DNA repair, consistently inducing the formation of RNA loops and promoting DNA damage. Treatment with PRMT5-targeting drugs significantly restrained the growth of experimental CCA without adverse effects and concomitantly induced the recruitment of CD4 and CD8 T cells to shrinking tumourous lesions., Conclusion: PRMT5 and MEP50 are frequently upregulated in human CCA, and PRMT5-targeting drugs have significant antitumoural efficacy in clinically relevant CCA models. Our findings support the evaluation of PRMT5 inhibitors in clinical trials, including their combination with cytotoxic and immune therapies., Competing Interests: Competing interests: MAA is editor of Gut. All other authors have no conflict of interest., (© Author(s) (or their employer(s)) 2024. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Objective: Intrahepatic cholangiocarcinoma (iCCA) is the second most common primary liver cancer with limited therapeutic options. KRAS mutations are among the most abundant genetic alterations in iCCA associated with poor clinical outcome and treatment response. Recent findings indicate that Poly(ADP-ribose)polymerase1 (PARP-1) is implicated in KRAS -driven cancers, but its exact role in cholangiocarcinogenesis remains undefined., Design: PARP-1 inhibition was performed in patient-derived and established iCCA cells using RNAi, CRISPR/Cas9 and pharmacological inhibition in KRAS -mutant, non-mutant cells. In addition, Parp-1 knockout mice were combined with iCCA induction by hydrodynamic tail vein injection to evaluate an impact on phenotypic and molecular features of Kras -driven and Kras -wildtype iCCA. Clinical implications were confirmed in authentic human iCCA., Results: PARP-1 was significantly enhanced in KRAS -mutant human iCCA. PARP-1-based interventions preferentially impaired cell viability and tumourigenicity in human KRAS -mutant cell lines. Consistently, loss of Parp-1 provoked distinct phenotype in Kras/Tp53- induced versus Akt/Nicd- induced iCCA and abolished Kras -dependent cholangiocarcinogenesis. Transcriptome analyses confirmed preferential impairment of DNA damage response pathways and replicative stress response mediated by CHK1. Consistently, inhibition of CHK1 effectively reversed PARP-1 mediated effects. Finally, Parp-1 depletion induced molecular switch of KRAS -mutant iCCA recapitulating good prognostic human iCCA patients., Conclusion: Our findings identify the novel prognostic and therapeutic role of PARP-1 in iCCA patients with activation of oncogenic KRAS signalling., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2024. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Objective: During the last decade, the management of gastric intestinal metaplasia (GIM) has been addressed by several distinct international evidence-based guidelines. In this review, we aimed to synthesise these guidelines and provide clinicians with a global perspective of the current recommendations for managing patients with GIM, as well as highlight evidence gaps that need to be addressed with future research., Design: We conducted a systematic review of the literature for guidelines and consensus statements published between January 2010 and February 2023 that address the diagnosis and management of GIM., Results: From 426 manuscripts identified, 16 guidelines were assessed. There was consistency across guidelines regarding the purpose of endoscopic surveillance of GIM, which is to identify prevalent neoplastic lesions and stage gastric preneoplastic conditions. The guidelines also agreed that only patients with high-risk GIM phenotypes (eg, corpus-extended GIM, OLGIM stages III/IV, incomplete GIM subtype), persistent refractory Helicobacter pylori infection or first-degree family history of gastric cancer should undergo regular-interval endoscopic surveillance. In contrast, low-risk phenotypes, which comprise most patients with GIM, do not require surveillance. Not all guidelines are aligned on histological staging systems. If surveillance is indicated, most guidelines recommend a 3-year interval, but there is some variability. All guidelines recommend H. pylori eradication as the only non-endoscopic intervention for gastric cancer prevention, while some offer additional recommendations regarding lifestyle modifications. While most guidelines allude to the importance of high-quality endoscopy for endoscopic surveillance, few detail important metrics apart from stating that a systematic gastric biopsy protocol should be followed. Notably, most guidelines comment on the role of endoscopy for gastric cancer screening and detection of gastric precancerous conditions, but with high heterogeneity, limited guidance regarding implementation, and lack of robust evidence., Conclusion: Despite heterogeneous populations and practices, international guidelines are generally aligned on the importance of GIM as a precancerous condition and the need for a risk-stratified approach to endoscopic surveillance, as well as H. pylori eradication when present. There is room for harmonisation of guidelines regarding (1) which populations merit index endoscopic screening for gastric cancer and GIM detection/staging; (2) objective metrics for high-quality endoscopy; (3) consensus on the need for histological staging and (4) non-endoscopic interventions for gastric cancer prevention apart from H. pylori eradication alone. Robust studies, ideally in the form of randomised trials, are needed to bridge the ample evidence gaps that exist., Competing Interests: Competing interests: No conflicts of interest are declared by MD-R, SS, HE-S, MB, NU, HT, LGC, DL, EL, AR, J-YF, LM, JB, EJK, EME-O. PM is a member of advisory board/lecturer of Aboca, Alfasigma, Allergosan, Bayer, Biocodex, Menarini advisory boards/lectures., (© Author(s) (or their employer(s)) 2024. No commercial re-use. See rights and permissions. Published by BMJ.)

Objective: Highly malignant pancreatic ductal adenocarcinoma (PDAC) is characterised by an abundant immunosuppressive and fibrotic tumour microenvironment (TME). Future therapeutic attempts will therefore demand the targeting of tumours and stromal compartments in order to be effective. Here we investigate whether dual specificity and tyrosine phosphorylation-regulated kinase 1B (DYRK1B) fulfil these criteria and represent a promising anticancer target in PDAC., Design: We used transplantation and autochthonous mouse models of PDAC with either genetic Dyrk1b loss or pharmacological DYRK1B inhibition, respectively. Mechanistic interactions between tumour cells and macrophages were studied in direct or indirect co-culture experiments. Histological analyses used tissue microarrays from patients with PDAC. Additional methodological approaches included bulk mRNA sequencing (transcriptomics) and proteomics (secretomics)., Results: We found that DYRK1B is mainly expressed by pancreatic epithelial cancer cells and modulates the influx and activity of TME-associated macrophages through effects on the cancer cells themselves as well as through the tumour secretome. Mechanistically, genetic ablation or pharmacological inhibition of DYRK1B strongly attracts tumoricidal macrophages and, in addition, downregulates the phagocytosis checkpoint and 'don't eat me' signal CD24 on cancer cells, resulting in enhanced tumour cell phagocytosis. Consequently, tumour cells lacking DYRK1B hardly expand in transplantation experiments, despite their rapid growth in culture. Furthermore, combining a small-molecule DYRK1B-directed therapy with mammalian target of rapamycin inhibition and conventional chemotherapy stalls the growth of established tumours and results in a significant extension of life span in a highly aggressive autochthonous model of PDAC., Conclusion: In light of DYRK inhibitors currently entering clinical phase testing, our data thus provide a novel and clinically translatable approach targeting both the cancer cell compartment and its microenvironment., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2024. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Competing Interests: Competing interests: None declared.

Competing Interests: Competing interests: None declared.

Acute severe ulcerative colitis (ASUC), characterised by bloody diarrhoea and systemic inflammation, is associated with a significant risk of colectomy and a small risk of mortality. The landmark trial of cortisone in 1955 was pivotal for two reasons: first, for establishing the efficacy of a drug that remains a first-line therapy today and, second, for producing the first set of disease severity criteria and clinical trial endpoints that shaped the subsequent ASUC trial landscape. Trials in the 1990s and at the turn of the millennium established the efficacy of infliximab and ciclosporin, but since then, there has been little progress in drug development for this high-risk population. This systematic review evaluates all interventional randomised controlled trials (RCTs) conducted in patients hospitalised with severe UC. It provides an overview of the efficacy of treatments from past to present and assesses the evolution of trial characteristics with respect to study populations, eligibility criteria and study designs over time. This review details ongoing RCTs in this field and provides a perspective on the challenges for future clinical trial programmes and how these can be overcome to help deliver novel ASUC therapies., Competing Interests: Competing interests: SH served as a speaker, a consultant and/or an advisory board member for Pfizer, Janssen, AbbVie, Lilly and Takeda, and in addition, she has received travel grants from Ferring, Pharmacosmos, Falk Pharma. VJ reports personal fees from AbbVie, Alimentiv (formerly Robarts Clinical Trials), Arena Pharmaceuticals, Asahi Kasei Pharma, Asieris, AstraZeneca, Avoro Capital, BMS, Celltrion, Endpoint Health, Enthera, Ferring, Flagship Pioneering, Fresenius Kabi, Galapagos, Gilde Healthcare, GSK, Genentech, Gilead, Innomar, JAMP, Janssen, Lilly, Merck, Metacrine, Mylan, Pandion, Pendopharm, Pfizer, Protagonist, Prometheus, Reistone Biopharma, Roche, Roivant, Sandoz, SCOPE, Second Genome, Sorriso Pharmaceuticals, Takeda, Teva, Topivert, Ventyx and Vividion outside the submitted work and fees from advisory board membership of AbbVie, Alimentiv (formerly Robarts Clinical Trials), Arena Pharmaceuticals, Asahi Kasei Pharma, Asieris, AstraZeneca, BMS, Celltrion, Ferring, Flagship Pioneering, Fresenius Kabi, Galapagos, Gilde Healthcare, GSK, Genentech, Gilead, Innomar, JAMP, Janssen, Lilly, Merck, Metacran, Mylan, Pandion, Pendopharm, Pfizer, Protagonist, Prometheus, Reistone Biopharma, Roche, Sandoz, SCOPE, Second Genome, Sorriso Pharmaceuticals, Takeda, Teva, Topivert, Ventyx and Vividion. BES reports consulting fees from Abbvie, Alimentiv, Amgen, Arena Pharmaceuticals, Artugen Therapeutics, AstraZeneca, Boehringer Ingelheim, Boston Pharmaceuticals, Calibr, Celgene, Celltrion, ClostraBio, Equillium, Enthera, Evommune, Fresenius Kabi, Galapagos, Genentech (Roche), Gilead Sciences, GlaxoSmithKline, Gossamer Bio, IndexPharmaceuticals, Innovation Pharmaceuticals, Inotrem, Kaleido, Kallyope, Merck, Morphic Therapeutics, MRM Health, Progenity, Prometheus, Protagonist Therapeutics, Q32 Bio, Sun Pharma, Surrozen, Target RWE, Teva, TLL Pharmaceutical, Ventyx Biosciences; consulting and speaking fees from Abivax; consulting and speaking fees and other support from Lilly; research grants, consulting and speaking fees and other support from Bristol Myers Squibb, Janssen, Pfizer, Takeda; research grants and consulting fees from Theravance Biopharma; and stock options from Ventyx Biopharma. PSD received consulting fees from Abbvie, Abivax, Adiso, Bristol Myers Squibb, GSK, Janssen, Lilly, Pfizer and Takeda and grant support from Bristol-Myers Squibb, Janssen, Pfizer and Takeda and licensing royalties from PreciDiag. SD has served as a speaker, consultant and advisory board member for Schering-Plough, AbbVie, Actelion, Alfa Wasserman, AstraZeneca, Cellerix, Cosmo Pharmaceuticals, Ferring, Genentech, Grunenthal, Johnson & Johnson, Millennium/Takeda, MSD, Nikkiso Europe GmbH, Novo Nordisk, Nycomed, Pfizer, Pharmacosmos, UCB and Vifor. LPB reports consulting fees from Abbvie, Abivax, Adacyte, Alimentiv, Amgen, Applied Molecular Transport, Arena, Banook, Biogen, BMS, Celltrion, Connect Biopharm, Cytoki Pharma, Enthera, Ferring, Fresenius Kabi, Galapagos, Genentech, Gilead, Gossamer Bio, GSK, IAC Image Analysis, Index Pharmaceuticals, Inotrem, Janssen, Lilly, Medac, Mopac, Morphic, MSD, Nordic Pharma, Novartis, Oncodesign Precision Medicine, ONO Pharma, OSE Immunotherapeuthics, Pandion Therapeuthics, Par' Immune, Pfizer, Prometheus, Protagonist, Roche, Samsung, Sandoz, Sanofi, Satisfay, Takeda, Telavant, Theravance, Thermo Fischer, Tigenix, Tillots, Viatris, Vectivbio, Ventyx, Ysopia, Grant support from Celltrion, Fresenius Kabi, Medac, MSD, Takeda. Lecture fees from Abbvie, Amgen, Arena, Biogen, Celltrion, Ferring, Galapagos, Genentech, Gilead, Janssen, Lilly, Medac, MSD, Nordic Pharma, Pfizer, Sandoz, Takeda, Tillots, Viatris. Travel support fees from Abbvie, Amgen, Celltrion, Connect Biopharm, Ferring, Galapagos, Genentech, Gilead, Gossamer Bio, Janssen, Lilly, Medac, Morphic, MSD, Pfizer, Sandoz, Takeda, Thermo Fischer, Tillots., (© Author(s) (or their employer(s)) 2024. No commercial re-use. See rights and permissions. Published by BMJ.)

Competing Interests: Competing interests: BV reports research support from AbbVie, Biora Therapeutics, Landos, Pfizer, Sossei Heptares and Takeda; speaker’s fees from Abbvie, Biogen, Bristol Myers Squibb, Celltrion, Chiesi, Falk, Ferring, Galapagos, Janssen, Lily, MSD, Pfizer, R-Biopharm, Sandoz, Takeda, Tillots Pharma, Truvion and Viatris; consultancy fees from Abbvie, Alfasigma, Alimentiv, Applied Strategic, Astrazeneca, Atheneum, BenevolentAI, Biora Therapeutics, Boxer Capital, Bristol Myers Squibb, Galapagos, Guidepont, Landos, Lily, Merck, Mylan, Nxera, Inotrem, Ipsos, Janssen, Pfizer, Progenity, Sandoz, Sanofi, Santa Ana Bio, Sapphire Therapeutics, Sosei Heptares, Takeda, Tillots Pharma and Viatris; stock options Vagustim.

Competing Interests: Competing interests: NKHdB served as a speaker for AbbVie and MSD and as consultant and principal investigator for Teva Pharma BV and Takeda and received an unrestricted research grant from Dr Falk Pharma, Teva Pharma BV, MLDS and Takeda, all outside the submitted work.

Competing Interests: Competing interests: JAF and ES have no conflicts of interest or financial ties to disclose. RPV reports research grants from Boston Scientific and Prion Medical, performed as a consultant for Boston Scientific and Cook Medical, and received speaker’s fee from Mylan and Zambon. CYP reports research grants from Gilead, Perspectum, advisory work for Pliant, Chemomab, NGM, and Takeda, and speaker’s fee from Tillotts. All outside the submitted work.

Competing Interests: Competing interests: None declared.

Epidemiological and translational data increasingly implicate environmental pollutants in inflammatory bowel disease (IBD). Indeed, the global incidence of IBD has been rising, particularly in developing countries, in parallel with the increased use of chemicals and synthetic materials in daily life and escalating pollution levels. Recent nationwide and ecological studies have reported associations between agricultural pesticides and IBD, particularly Crohn's disease. Exposure to other chemical categories has also been linked with an increased risk of IBD. To synthesise available data and identify knowledge gaps, we conducted a systematic review of human studies that reported on the impact of environmental pollutants on IBD risk and outcomes. Furthermore, we summarised in vitro data and animal studies investigating mechanisms underlying these associations. The 32 included human studies corroborate that heavy and transition metals, except zinc, air pollutants, per- and polyfluorinated substances, and pesticides are associated with an increased risk of IBD, with exposure to air pollutants being associated with disease-related adverse outcomes as well. The narrative review of preclinical studies suggests several overlapping mechanisms underlying these associations, including increased intestinal permeability, systemic inflammation and dysbiosis. A consolidated understanding of the impact of environmental exposures on IBD risk and outcomes is key to the identification of potentially modifiable risk factors and to inform strategies towards prediction, prevention and mitigation of IBD., Competing Interests: Competing interests: MF reports receiving lecture/consultant fees from Abbvie, Ferring, Tillots, MSD, Biogen, Amgen, Fresenius, Hospira, Sandoz, Pfizer, Bristol Myers Squibb, Celgene, Gilead, Boehringer, Eli Lilly, Nordic-Pharma, Arena, Galapagos, Janssen and Takeda. JFC reports receiving research grants from AbbVie, Janssen Pharmaceuticals and Takeda; receiving payment for lectures from AbbVie, Amgen, Allergan, Ferring Pharmaceuticals, Shire and Takeda; receiving consulting fees from AbbVie, Amgen, Arena Pharmaceuticals, Boehringer Ingelheim, Bristol Myers Squibb, Celgene Corporation, Eli Lilly, Ferring Pharmaceuticals, Galmed Research, Glaxo Smith Kline, Geneva, Iterative Scopes, Janssen Pharmaceuticals, Kaleido Biosciences, Landos, Otsuka, Pfizer, Prometheus, Sanofi, Takeda, TiGenix and hold stock options in Intestinal Biotech Development.MA reports consulting for Douglas Pharmaceutical., (© Author(s) (or their employer(s)) 2024. No commercial re-use. See rights and permissions. Published by BMJ.)