Inflammatory Bowel Diseases

BackgroundIntestinal barrier dysfunction is a hallmark of inflammatory bowel diseases (IBD). This condition causes intoxication and immune hyperactivation. Understanding the events underlying epithelial barrier disruption during chronic inflammation is key to developing barrier-restoring therapies. Filamentous actin (F-actin) is essential for maintaining polarity and junctional integrity. However, the contribution of F-actin dynamics to IBD-associated barrier dysfunction remains unclear. ObjectiveWe aimed to examine actin cytoskeleton integrity during chronic colitis across mouse models and human patients and identify potential regulators of cytoskeleton dynamics. DesignF-actin and junctional proteins were analyzed in three models of chronic colitis (Muc2 KO, DSS-induced colitis, adoptive transfer colitis) using confocal microscopy. Claudin-3 interactors were identified by immunoprecipitation and proteomics. Intestinal organoids were used to assess the effect of F-actin disruption on barrier integrity. Metabolomic and gene expression analyses identified candidate pathways, further validated by chemical inhibition. Biopsies from patients with ulcerative colitis (UC) were examined using transmission electron microscopy and confocal microscopy. ResultsDisrupted actin dynamics emerged as a critical driver of epithelial barrier dysfunction in chronic colitis. An imbalance between polymeric and monomeric actin impaired barrier integrity in vivo and in 3D organoids. Immunoprecipitation identified actin and associated factors as the primary interactors of claudin-3 with reduced interaction during inflammation. Ceramide metabolism was revealed as a potential regulator of F-actin and intestinal barrier. In UC patients, we confirmed concurrent disruption of junctions and F-actin. ConclusionsF-actin dysregulation contributes to barrier dysfunction in IBD and targeting its modulators, including ceramide biosynthesis, represents a novel therapeutic strategy. WHAT IS ALREADY KNOWN ON THIS TOPICO_LIEpithelial damage and increased paracellular permeability are key characteristics of inflammatory bowel diseases. C_LIO_LIParacellular permeability is partially attributed to the downregulation of junction proteins but this mechanism does not explain all clinical observations. C_LIO_LIIn the Muc2 KO mouse model of chronic colitis, F-actin organization and membrane localization of tight junction protein claudin-3 are disrupted, although protein expression levels remain unchanged. C_LI WHAT THIS STUDY ADDSO_LIF-actin dynamics is impaired in the intestinal epithelium across three different mouse models of chronic colitis and IBD patients. C_LIO_LIDisruption of F-actin dynamics leads to impaired membrane localization of tight and adherens junction proteins and increased intestinal epithelial permeability in vivo and in colonic organoids. C_LIO_LIInhibition of ceramide biosynthesis rescues F-actin polymerization and intestinal barrier integrity in mouse chronic colitis models. C_LI HOW THIS STUDY MIGHT AFFECT RESEARCH, PRACTICE OR POLICYO_LITargeting F-actin dynamics is a promising approach to improve gut epithelial integrity. C_LIO_LI"Ceramide-F-actin-junction" axis is proposed as one of the mechanisms behind epithelial barrier disruption in colitis. Therapeutic targeting of this axis represents a promising path for restoring gut integrity. C_LI

BackgroundKeratins, a major subgroup of intermediate filament proteins, play a critical role in maintaining epithelial barrier and intracellular epithelial integrity. Studies have demonstrated possible links between inflammatory signaling and colonic keratins type II K8, and type I K18, K19 and K20, in animal models of colitis, and in patients with Inflammatory Bowel Disease (IBD). K7 is de novo expressed in patients with the IBD subtypes Ulcerative Colitis (UC) and Crohns Disease (CD). However, the histopathological roles of colonocyte keratins across IBD, microscopic colitis (MC), and Irritable Bowel Syndrome (IBS) remain poorly understood. Given the established utility as biomarkers in cancer diagnostics, we investigated whether keratin expression patterns could be used to distinguish inflammatory and functional colonic disorders. MethodsBiobank samples from patients with IBD (n=27), MC (n=18), IBS (n=32) and healthy controls (n=31), were collected and immunohistochemically stained for K7, K8, K18, K19, and K20. Digital image analysis quantified staining intensities, which were correlated with histopathological severity scores and clinical parameters. ResultsColonic keratin expression was significantly elevated in IBD, particularly in UC, while they were decreased in MC, and unaltered in IBS. Notably, K8 and K19 expression were strongly associated with areas of severe epithelial damage in IBD. Keratin expression was most pronounced in patients who had undergone colectomy due to treatment-resistant IBD. DiscussionKeratin changes in IBD and MC but not in IBS highlight their importance in maintaining barrier homeostasis. Whether these changes are causes or consequences for these diseases will warrant further research.

BackgroundCrohns disease (CD) is a chronic inflammatory disorder of the gastrointestinal tract characterized by high post-operative recurrence (POR) rates, reaching up to 90% within one year. Current clinical and endoscopic predictors show limited accuracy. ObjectiveThis study aimed to identify molecular mechanisms associated with POR at the time of surgery through integrated transcriptomic and bacteriomic analyses of ileal tissue. DesignIleal samples were obtained during surgery from 20 patients with CD and 10 inflammatory bowel disease-free controls, with an independent validation cohort of 49 patients with CD. POR was evaluated every six months using ileocolonoscopy and defined by Rutgeerts score. Host gene expression and tissue-associated microbiome profiles were integrated using correlation and pathway enrichment analyses to uncover host-microbe interactions linked to POR. ResultsIn the inflamed mucosa of patients who developed endoscopic POR, we identified a novel immune interaction involving the Porphyromonadaceae family, mainly Parabacteroides gordonii, which was slightly depleted. This depletion was associated with downregulation of epithelial barrier and tissue repair genes, including TFF1 and LSR, findings confirmed in the validation cohort. Porphyromonadaceae abundance positively correlated with short-chain fatty acid levels, particularly propionate. Additionally, omics integration revealed an association between Xanthomonadaceae and increased expression of ITGAM, a gene involved in neutrophil activation. ConclusionThese results highlight microbial-host gene interactions associated with POR. The pathogenic ITGAM-driven immune signature and the protective Porphyromonadaceae-TFF1-propionate axis supporting epithelial integrity may enable microbiome-informed prognostic tools and therapeutic strategies for CD POR. O_LIWhat is already known on this topic: Post-operative recurrence in Crohns disease is linked to microbial dysbiosis, particularly reduced diversity and expansion of Enterobacteriaceae. However, how microbial changes translate into host molecular mechanisms driving POR remains unclear. C_LIO_LIWhat this study adds: This prospective multi-omic study identifies a disrupted Porphyromonadaceae-SCFA-epithelial barrier axis and the participation of neutrophil responses in patients who develop POR at surgery time. C_LIO_LIHow this study might affect research, practice or policy: The findings provide mechanistic targets for microbiome-informed risk stratification and prevention of POR. They support development of microbial or metabolite-based interventions aimed at restoring epithelial barrier function after surgery. C_LI

Background & AimsFood-related adverse reactions are frequently reported by patients with inflammatory bowel disease (IBD), but the underlying mechanisms are poorly understood. We investigated how intestinal inflammation and the microbiota contribute to the development of adverse food reactions. MethodsWe sensitized mice to different foods (dairy and gluten) after intestinal inflammation (chemically- and hapten-induced models), and then re-exposure to the sensitized foods through diet enrichment. To study whether inflamed microbiota facilitates adverse food reactions, we employed gnotobiotic models and bacterial supplementation experiments. We assessed markers of intestinal inflammation and sensitization, clinical responses, RNA transcripts, and microbiota composition and function. In a translational approach, we recruited IBD patients in remission and healthy controls, recorded self-reported food intolerances and clinical responses to triggering foods, and feces for gut microbiota analyses were collected. ResultsIntestinal inflammation facilitates food sensitization by disrupting microbial antigen metabolism, recruiting mast cells to the colon, and promoting mucosal IgE production. In gnotobiotic models, inflammation-driven depletion of colonic bacteria involved in food digestion contributed to food sensitization. Upon re-exposure to triggering foods, sensitized mice experienced visceral pain and low-grade inflammation through mast-cell mediated mechanisms, which also worsened experimental colitis. Supplementation with depleted bacteria or treatment with mast cell stabilizers attenuated food-driven responses. In IBD patients, self-reported food intolerances were common and associated with microbial disruption and depletion of food-metabolizing bacteria. ConclusionMicrobial metabolism of foods is disrupted after intestinal inflammation. This facilitates food sensitization, through colonic mast cell-mediated immune responses, which may explain the high number of adverse food reactions reported by IBD patients. WHAT YOU NEED TO KNOWO_ST_ABSBackground and contextC_ST_ABSPatients with inflammatory bowel disease (IBD) frequently report adverse food reactions, but the underlying mechanisms are not well understood. New findingsIntestinal inflammation promotes food sensitization by depleting bacteria that degrade food triggers. IBD patients in remission with food intolerances show reduced microbial diversity and loss of bacteria involved in digesting food triggers. LimitationsWe used chemically- and hapten-induced mouse models in this study due to the importance of monitoring inflammation onset. Food-driven immune reactions in the mucosa of IBD patients were not performed. Clinical research relevanceImpaired microbial food metabolism is linked to adverse food reactions in IBD. Microbiome-based therapies, such as probiotics capable of degrading dairy or gluten, should be considered for IBD patients with food intolerances. Basic research relevanceWe identified a novel mechanism in which microbial disruption caused by intestinal inflammation leads to adverse food reactions and worsened colitis in preclinical models. Restoring the microbial capacity to digest trigger foods reverses these effects. Lay AbstractIntestinal inflammation facilitates sensitization to gluten and dairy proteins by depleting microbes that digest them, contributing to the increase in adverse food reactions among IBD patients.

BackgroundPatients with chronic immune-mediated disorders (IMIDs), including inflammatory bowel disease (IBD), are at increased risk of cardiovascular disease. While advanced therapies show cardioprotective effects in other IMIDs, their impact on major adverse cardiovascular events (MACE) in IBD remains unclear. We conducted a meta-analysis of randomized controlled trials (RCTs) and observational studies evaluating MACE risk with advanced therapies in IBD. MethodsSystematic search of PubMed, Embase and Cochrane Central identified 43 high-quality studies (36 RCTs,7 observational studies) published between 2002 and 2024. Primary analyses estimated odds ratios (OR) for MACE comparing advanced therapy to placebo, with secondary analyses stratified studies by drug class and length of follow-up. ResultsPlacebo-controlled RCTs showed a nonsignificant trend toward reduced MACE risk (OR: 0.60; 95% CI: 0.24-1.51), with similar findings after continuity correction for zero-event studies (OR: 0.87; 95% CI: 0.45-1.68). Class-specific trends suggested lower MACE risk with IL-12/IL-23 inhibitors (OR: 0.35; 95% CI: 0.05-2.21), JAK inhibitors (OR: 0.57; 95% CI: 0.16-2.06), and a potential increase with anti-TNF agents (OR: 3.04; 95% CI: 0.31-29.47), though none reached statistical significance. Long-term follow-up studies showed consistent findings. Observational studies suggested lower MACE risk for anti-TNF therapies (OR: 0.29; 95% CI: 0.21-0.40), but not for IL-12/IL-23 (OR: 4.41; 95% CI: 0.49-39.28) or JAK inhibitors (OR: 1.57; 95% CI: 0.86-2.84). ConclusionAdvanced therapies did not demonstrate a clear increase or decrease in cardiovascular risk in IBD. The discrepancies between RCTs and observational studies underscore the urgent need for rigorous-designed observational research with long-term follow-up to evaluate the real-world impact of advanced therapies on MACE risk. SummaryThis study evaluated cardiovascular safety of advanced therapies in inflammatory bowel disease. Findings showed no clear signal of decreased major cardiovascular risk compared with conventional treatment, highlighting the need for continued monitoring through long-term and real-world evidence. Key MessagesO_LIWhat is already known? Patients with IBD are at increased risk of cardiovascular events, and the impact of advanced therapies on this risk remains uncertain. C_LIO_LIWhat is new here? This meta-analysis integrates data from randomized and observational studies and found no significant association between advanced therapies and MACE. C_LIO_LIHow can this study help patient care? Findings show no clear signal of decreased cardiovascular risk with advanced IBD therapies, though continued evaluation is warranted. C_LI

BackgroundRecent genome wide association studies (GWAS) performed by our laboratory identified polymorphisms at the locus containing the gene, cAMP-responsive element modulator (CREM), that influence Entamoeba histolytica+ diarrheal disease susceptibility in children. CREM is a cAMP-responsive transcription factor that regulates genetic expression and epigenetic modulation in a context- and cell-specific manner. Polymorphisms at this locus have been previously associated with IBD susceptibility, suggesting CREM regulates enteric inflammation in infectious and autoimmune colitis. MethodsMice were generated with either a tamoxifen-inducible global deletion or an intestinal epithelial cell (IEC)-specific deletion of Crem. Dextran-sodium sulfate (DSS) was administered to chemically induce colitis and mice were assayed for weight loss, clinical score, spectral flow cytometry of colonic lamina propria and mesenteric lymph node white blood cells, and shallow shotgun whole genome sequencing of fecal samples. ResultsTamoxifen-inducible global deletion of Crem significantly ameliorated DSS-colitis severity as measured by clinical scoring and weight loss over the course of disease (p = 2.29 x 10-15, p = 2.24 x 10-21, respectively). Protection was not phenocopied when Crem was deleted exclusively in IECs. When sampled during acute colitis, protection seen in Crem-deleted mice was associated with a significant increase in macrophages, and ROR{gamma}t+ regulatory (pTregs) and T helper (Th17) cells in the colonic lamina propria, along with an increase of T-follicular like helper cells in the mesenteric lymph node. ConclusionsInducible global deletion of Crem reduced the severity of DSS colitis while increasing colonic macrophages, ROR{gamma}t+ regulatory (pTregs) and T helper (Th17) cells. Future work will investigate the aforementioned cell types to determine the mechanism by which CREM aggravates DSS-colitis, thereby defining the immunoregulatory role of CREM in intestinal inflammation with the goal of identifying new therapeutic targets for IBD.

Background & AimsUnchecked inflammation in Eosinophilic esophagitis (EoE) leads to esophageal fibrosis and eventual stricture. Differentiated fibroblasts, termed myofibroblasts, are the main effector cells in fibrosis, responsible for secreting extracellular matrix proteins leading to tissue stiffness. Regulating myofibroblasts has not been explored as a therapeutic possibility in the fibrostenotic esophagus. Herein, we aim to investigate the efficacy of Prostaglandin E2 (PGE2) in dedifferentiation of the EoE myofibroblast. MethodsWe evaluated the efficacy and mechanism of myofibroblast dedifferentiation using fetal esophageal fibroblasts (FEF3), patient-derived fibroblasts, and a murine model of EoE. ResultsFibrosis markers (SMA, FN1, and COL1A1) and contractility of myofibroblasts were significantly decreased by PGE2 via the cAMP pathway. PGE2 treatment decreased nuclear accumulation of phospho-Smad2/3-YAP complex and induced phospho-YAP proteasomal degradation. Transcriptome analyses of FEF3 treated with TGF{beta} or PGE2 revealed that the Integrin1 pathway, and specifically thrombospondin 1 (THBS-1), was significantly upregulated by TGF{beta} and downregulated by PGE2, as supported by pseudo-bulk single-cell RNA-seq of EoE biopsies. THBS-1 was shown to be regulated by PGE2 via the cAMP/YAP pathway, and its knockdown induced myofibroblasts dedifferentiation. In a murine model of EoE, Butaprost, agonist of the E-prostanoid G protein-coupled receptor 2, treatment significantly reduced the expression of THBS-1, SMA, and FN1 along with a decrease in YAP nuclear translocation. Additionally, collagen fiber organization in the lamina propria was markedly reduced. ConclusionPGE2 promotes dedifferentiation of myofibroblasts in EoE via the cAMP/YAP/ THBS-1 pathway. Our data suggest that PGE2 is a promising treatment strategy for EoE with stenosis. What You Need to KnowO_ST_ABSBackground and ContextC_ST_ABSIn Eosinophilic esophagitis, unchecked inflammation and tissue stiffness drives fibroblast differentiation and fibrostenosis of the esophagus, yet targeting myofibroblasts as regulators of extracellular matrix deposition in fibrostenotic disease remains clinically unexplored. New FindingsProstaglandin E2 promotes dedifferentiation of myofibroblasts in eosinophilic esophagitis via the cAMP/YAP pathway, with Thrombospondin-1 identified as a critical YAP regulated target driving fibrostenosis. LimitationsThis study focused on fibroblast-specific mechanisms. The effects of PGE2 on esophageal epithelial differentiation, barrier function, and immune cell recruitment in EoE remain to be determined. Clinical Research RelevanceThis study demonstrates proof-of-concept that pharmacological reversal of established fibrosis is achievable in EoE. PGE2 and its EP2-selective agonists represent translatable therapeutic targets for fibrostenotic EoE--a patient population that remains treatment-refractory to current immunosuppressive approaches. Basic Research RelevanceThe cAMP/YAP/THBS-1 signaling in fibroblasts emerges as a critical therapeutic target for esophageal fibrosis. Importantly, this work demonstrates that terminally differentiated myofibroblasts retain remarkable plasticity and can dedifferentiate--challenging the paradigm that fibrosis is irreversible.

PurposeHirschsprung-associated enterocolitis remains a major postoperative complication of Hirschsprungs disease (HD), and impaired epithelial barrier integrity has been proposed as a contributing factor. In this study, we investigated whether 12-hydroxyheptadecatrienoic acid (12-HHT), an endogenous leukotriene B4 receptor 2 (BLT-2) agonist, enhances the epithelial barrier and exerts anti-inflammatory effects in patient-derived colonic organoids. MethodsNormoganglionic specimens from rectal/rectosigmoid HD at pull-through (HD-N; n = 8) and transverse colon specimens from anorectal malformation (ARM) at colostomy closure (n = 10) were used to generate colonic organoids. Epithelia were isolated using ethylenediaminetetraacetic acid and subsequently embedded in Matrigel. Baseline expression of TJP1, TJP2, F11R (encoding junctional adhesion molecule-A), JAM2, CLDN1, CLDN3, CLDN4) and LTB4R2 (encoding BLT-2) was assessed by qPCR and immunoblotting. Organoids were then treated with 12-HHT (0.4, 2, or 10 M) for 7 days, followed by qPCR. Additional experiments assessed cytokine expression (IL1B, IL6) and TJPs after 24 h with tumor necrosis factor- (TNF-, 100 ng/mL) plus phosphate buffered saline or 12-HHT. Barrier function was evaluated using FITC-dextran influx assays. ResultsHD-N and ARM organoids exhibited similar growth efficiencies. Baseline expression for F11R, JAM2, CLDN1, CLDN3, CLDN4, and LTB4R2 was significantly lower in HD-N than in ARM. TJPs were upregulated by 12-HHT at 2 and 10 M in both groups, with stronger effects in ARM. In HD-N organoids, 10 M 12-HHT suppressed TNF--induced IL1B and IL6 elevation mitigated tight junction proteins (TJPs) downregulation more effectively than 2 M. 12-HHT attenuated TNF--induced FITC-dextran influx in HD-N organoids. Conclusion12-HHT may exert anti-inflammatory effects by integrating TJPs of HD-N.

BackgroundAnti-tumor necrosis factor (anti-TNF), particularly infliximab, have transformed inflammatory bowel disease (IBD) management, but their high cost imposes a significant economic burden. Infliximab biosimilars were introduced to reduce the unmet needs. Despite the approval of infliximab biosimilars, real-world evidence of cardiovascular safety and effectiveness of infliximab biosimilars is lacking among patients with IBD. In this trial emulation, we compared the effectiveness and cardiovascular safety between patients who initiated infliximab reference product (IFX-RP) and biosimilars (IFX-BP). MethodsUsing the Merative Marketscan Research database (2011-2023), we conducted a retrospective cohort study to emulate the target trial where biologic-naive adults were randomly assigned to initiate IFX-RP or IFX-BP. Primary outcomes included healthcare resource utilization (HRU), and incidence of major adverse cardiovascular events (MACE) over one year. Propensity score matching was applied to mimic the randomization. Both intention-to-treat and per-protocol effects were estimated. ResultsAfter matching, 850 patients (425 per group) were included. HRU was comparable between IFX-RP and IFX-BP groups across outpatient visits, hospitalizations, surgeries, and emergency visit. During follow-up, MACE events were more frequent in the IFX-BP group (9 vs. 3), with an incidence rate ratio (IRR) of 3.04 (95% CI: 0.82-11.23). Although the difference was not statistically significant, consistent directional trends were observed across analyses. Sensitivity analyses supported primary results. ConclusionOur study found comparable effectiveness between IFX-RP and IFX-BP in routine clinical care. While cardiovascular events were infrequent, the potential signal suggesting increased MACE risk associated with infliximab biosimilars warrants further investigation. Continued pharmacovigilance is essential to ensure the cardiovascular safety of biosimilars. SummaryInfliximab biosimilars, introduced to reduce the economic burden of anti-TNF therapy in IBD, demonstrated comparable real-world effectiveness to the infliximab reference product in a target trial emulation using Merative MarketScan data, while a potential signal of increased cardiovascular risk underscores the need for ongoing pharmacovigilance and further investigation. Key MessagesO_LIWhat is known? Infliximab biosimilars demonstrate comparable efficacy and safety to the reference product in IBD, but cardiovascular outcomes remain underexplored. C_LIO_LIWhat is new here? This U.S. real-world study emulating a target trial found similar effectiveness between infliximab reference and biosimilar products, with a possible trend toward increased cardiovascular risk in biosimilar users. C_LIO_LIHow can this study help patient care? Findings highlight the need for continued pharmacovigilance and cardiovascular monitoring when prescribing infliximab biosimilars to optimize safety in IBD management. C_LI

IntroductionPrevious studies have shown that Aquamin(R), a multi-mineral extract from red marine algae, enhances barrier integrity proteins in the human colon. These findings prompted further investigation into Aquamin(R)s effects on gastrointestinal barrier function and permeability. MethodsSubjects with mild or in remission ulcerative colitis (UC) and healthy controls were enrolled in an open-label trial and received Aquamin(R) capsules (800 mg calcium/day) for 90 days. Intestinal permeability was evaluated before and after the 90-day intervention by urinary mannitol excretion after ingestion of a 5 g mannitol solution, with collections across several time intervals (pre-drink, 0-2 h, 2-8 h, and 8-24 h). The primary outcome was the change in mannitol excretion. Serum samples were also collected to assess liver and renal function. ResultsIn this pilot study (NCT04855799), which included UC patients and healthy controls (n = 8 per group), baseline urine mannitol levels in the 0-2 h sample were 54% higher in UC patients compared to healthy subjects (p = 0.006). Following 90 days of Aquamin(R) supplementation, urinary mannitol levels in UC patients decreased by 28%, 26%, and 41% at the 0-2 h, 2-8 h, and 8-24 h timepoints, respectively; the reduction at the 0-2 h interval reached statistical significance (p = 0.015). Overall, Aquamin(R) supplementation reduced total post-intervention mannitol excretion by 29% (p = 0.024). Aquamin(R) was well tolerated, with no serious adverse events reported. The serum metabolic panel revealed a modest but statistically significant reduction in alkaline phosphatase levels after 90 days of intervention. ConclusionThese results provide preliminary evidence that Aquamin(R) supplementation beneficially modulates gut barrier function and supports epithelial integrity in UC patients. These findings support further investigation of Aquamin(R) as a safe and promising adjunct to current UC management strategies, with potential utility as a barrier therapy in UC. SummaryAquamin(R) supplementation for 90 days reduced intestinal permeability in ulcerative colitis patients, as measured by urinary mannitol excretion. The intervention was well tolerated, suggesting Aquamin(R) may be a safe, promising adjunct for enhancing gut barrier function in UC management.

BackgroundGestational exposures may contribute to the newborns lifetime risk of inflammatory bowel disease (IBD). While gestational influences are associated with IBD onset, the causality and confounding of such exposures are difficult to ascertain. The neonatal metabolome provides a metabolic snapshot of gestational influences. ObjectiveWe tested the neonatal metabolomes ability to predict future IBD, to assess whether gestational exposures are reflected in early molecular precursors of the disease. MethodsWe profiled dried blood spots from 520 newborns who later developed IBD and matched controls using high-resolution untargeted mass spectrometry metabolomics (1,350 QC-passing metabolites). Genotyping was available for 1,009 of these individuals. PERMANOVA confirmed assay sensitivity to gestational exposures, gradient boosting was used for prediction. ResultsThe neonatal metabolome significantly captured maternal smoking, birth weight, and gestational age (p < 0.001), but explained minimal variance in IBD status (R2 = 0.09%, p = 0.390) and showed no predictive power for IBD (AUC = 0.51, 95% CI 0.50-0.52, p = 0.585). Stratifying by disease subtype and age of onset did not improve performance. In contrast, genetic risk scores were modestly predictive (CD: AUC = 0.64, p < 5.11x10-14; UC: AUC = 0.63, p < 7.65x10-{superscript 1}{superscript 2}), but uncorrelated with neonatal metabolomic profiles (CD: p = 0.650; UC: p = 0.970), suggesting a later-age effect. ConclusionsUsing a large, comprehensively profiled cohort, we demonstrate that neonatal metabolomic profiles sensitively capture gestational signatures, but not the overall future IBD risk. Our findings suggest that most IBD risk accumulates later in life, beyond gestational molecular imprints.

Background and ObjectivesInflammatory bowel disease (IBD) involves dysregulated immune responses and chronic intestinal inflammation. The nod-like receptor pyrin domain-containing 3 (NLRP3) inflammasome plays a critical role in IBD pathogenesis, but regulatory mechanisms remain not fully understood. Mitsugumin 53 (MG53, also known as TRIM72), originally identified as a critical membrane repair protein, has emerged as a novel regulator of inflammatory processes. To investigate the protective role of MG53 in colitis and elucidate its mechanisms in regulating NLRP3 inflammasome activation in IBD. MethodsWe used dextran sodium sulfate (DSS)-induced colitis models comparing MG53 knockout (MG53-/-) and wild-type (WT) mice, assessing disease severity, MG53 tissue uptake, and therapeutic effects of recombinant human MG53 (rhMG53). In vitro studies examined rhMG53s effects on NLRP3 inflammasome activation, caspase-1 cleavage, interleukin-1{beta} (IL-1{beta}) secretion, and MG53-NLRP3 interactions. ResultsMG53-/- mice showed more severe colitis with increased weight loss, higher disease activity scores, shortened colons, and greater inflammation. DSS treatment induced the accumulation of circulating MG53 in inflamed colonic tissue. rhMG53 administration ameliorated colitis severity in MG53-/- mice and dose-dependently suppressed NLRP3 inflammasome activation in vitro. MG53 interacted with NLRP3 and reduced apoptosis-associated speck-like protein containing a CARD (ASC) speck formation and NLRP3 oligomerization without affecting upstream signaling or NLRP3 stability. ConclusionMG53 is a physiological regulator of NLRP3 inflammasome activation that protects against colitis, suggesting therapeutic potential for IBD.

Background & AimsCeliac disease is a wheat-induced immune-mediated enteropathy. Intestinal organoid models for adult stem cell-based celiac disease exist, but planar intestinal models derived from celiac disease patients that would allow direct assessment from both sides of the epithelium have been lacking. We aimed to bridge this gap by setting up a two-dimensional in vitro model based on small intestinal epithelial cells (SIECs) derived from induced pluripotent stem cells (iPSC) from celiac disease patients. MethodsIPSCs from celiac disease and control patients were sequentially differentiated towards SIECs. The models applicability was tested under cytokine stimuli. ResultsCeliac disease and control patient iPSCs matured similarly towards SIECs. However, they had inherent gene expression differences in inflammation- and immune-related genes, such as IRF1 and HLA-DRB1. Both iPSC-SIECs responded in a SIEC-specific manner to the cytokine stimulation. The response in celiac disease iPSC-SIECs was attenuated compared with that of control iPSC-SIECs. ConclusionsThe data confirm that iPSC-derived SIECs represent an appropriate platform for studying inflammation-associated enteropathies, such as celiac disease, but also suggest that there might be inherent patient-specific or cell type-specific differences in the responses.

Anemia is one of the most debilitating and frequent complications of inflammatory bowel diseases (IBD) and is often treated with iron supplementation, which has limited efficacy. Damaged intestinal barrier function is a hallmark of IBD and causes the translocation of endotoxins from gut bacteria into the bloodstream. In a previous study in mice, we reported that endotoxin suppresses erythropoiesis by reprogramming erythroblastic island macrophages (EBI M{varphi}). Here, we show that IBD patients and mice with acute colitis developed endotoxemia associated with anemia. Endotoxemia in IBD patients was negatively correlated with blood erythrocyte counts. In line with this, mice with acute colitis caused by drinking water containing dextrin sodium sulphate (DSS) had endotoxemia together with anemia characterized by reduced red blood cell counts, hemoglobin content and hematocrit., and reduced medullary erythropoiesis which was in part compensated by increased extramedullary erythropoiesis. As the endotoxin receptor TLR4 is expressed by CD169+ gut-resident macrophages and erythroid island macrophages in the bone marrow, we tested the hypothesis that TLR4 expressed by these CD169+ macrophages mediate both inflammatory colitis and anemia. Indeed, mice with conditional deletion of the Tlr4 gene specifically in CD169+ tissue-resident macrophages were protected from DSS-induced anemia and colitis. In addition, treatment of DSS mice with the TLR4 inhibitor C34 abated inflammation and anemia. These results suggest that endotoxins leaking from the inflamed gut may play a crucial role in IBD and associated anemia and that drugs targeting TLR4 may protect against IBD-associated anemia. Key pointsO_LIPatients with IBD and mice with acute colitis are anemic with increased endotoxemia and inflammation. C_LIO_LIEndotoxemia is inversely correlated with blood erythrocyte counts in IBD patients. C_LIO_LIConditional deletion of endotoxin receptor gene Tlr4 specifically in CD169+ tissue-resident macrophages or administration of synthetic TLR4 inhibitor significantly reduced colitis-induced anemia in mice. C_LI

BackgroundCurrent British Society of Gastroenterology (BSG) guidelines misclassify metachronous lesion risk after polypectomy in approximately 40% of patients. Building on evidence that immune exclusion drives progression of adenomas to colorectal cancer, this study examined immune profiles in screen-detected adenomas as a predictive biomarker for metachronous lesion risk. MethodsPatients undergoing polypectomy within the Scottish Bowel Screening Programme, with surveillance colonoscopy between 6 months and 6 years were included. Chromogenic immunohistochemistry (IHC; n=2642), 6-plex multiplex immunofluorescence (mIF; n=334), and spatially resolved 6000-plex single cell transcriptomics (n=7) were applied to adenoma microarrays. Cell density and location were measured using QuPath. Hierarchical then K-means clustering was used to define immune cell density-based clusters, which were compared to future lesion events using Kaplan-Meier curves and the log rank test. ResultsAfter adjustment for age, sex, site, size and dysplasia, adenoma CD3+ T cell density was significantly associated with future colorectal neoplasia (HR 1.43, 95% CI 1.19-1.71, p<0.001). Using mIF three immune cell density clusters were identified; 1) high T cell density, low macrophage density, 2) low T cell density, low macrophage density, and 3) high T cell, macrophage and SMA density, with significant differences in future lesion risk (Cluster 1: 22%, Cluster 2: 41%, Cluster 3: 36%, p=0.032). Bulk RNAseq and spatial transcriptomic analysis revealed significant variation in T cell and macrophage co-location and gene expression profiles between clusters. ConclusionAdenoma immune contexture emerges as a determinant of future metachronous lesion risk, offering a novel biomarker to refine surveillance and reduce disease burden. SummaryWhat is already known on this topic: O_LIPost-polypectomy surveillance is currently recommended to patients with high-risk pathological features to detect metachronous lesions and cancer. However current guidelines misclassify risk in a proportion of patients, leading to unnecessary surveillance for some, whilst falsely reassuring others. C_LI What this study adds: O_LIAnalysis of this large post-polypectomy surveillance cohort reveals that adaptive immune responses within removed index adenomas predicts low risk of metachronous lesions, while an immune excluded phenotype signals higher risk, independent of pathological characteristics, and patient risk factors. C_LI How this study might affect research, practice or policy: O_LIDefining immune cell spatial distributions and interactions that drive future adenoma and cancer risk will enable more precise risk stratification for surveillance, informing surveillance guidelines and shaping targeted colorectal cancer prevention strategies. C_LI

ObjectivesFree fatty acid receptors 2 and 3 (FFA2 and FFA3) are activated by nutrient-derived metabolites such as short-chain fatty acids (SCFAs) and ketone bodies, produced by the gut microbiota and host, respectively. This study aimed to investigate the intracellular signaling pathways recruited in glucagon-like peptide-1 (GLP-1) releasing enteroendocrine cells following activation of FFA2 and FFA3 to resolve the impact of nutrient status on enteroendocrine cell function. MethodsExperiments were performed using primary mouse colonic cultures and the mouse enteroendocrine cell line, GLUTag cells. Expression analysis by bulk RNA sequencing was used to determine expression of FFA2 and FFA3 in GLP-1 releasing cells. Measurement of GLP-1 secretion by sandwich ELISA was used to assess enteroendocrine cell function. Live-cell measurements of intracellular calcium and cAMP levels were performed to assess canonical second messenger signaling pathways. ResultsA SCFA mixture stimulated GLP-1 secretion from both primary mouse colonic cultures and GLUTag cells. In GLUTag cells, the FFA2 ligand 4-CMTB inhibited GLP-1 release independent of Gaq- and Gai-signaling as neither YM-254890 (Gaq inhibitor) nor pertussis toxin (Gai- uncoupler) altered its effect. However, 4-CMTB did elevate cAMP levels, suggesting an indirect mechanism for the increase in cAMP production. Stimulation of FFA2 with the Gai-biased ligand AZ1729 or the ketone body acetoacetate inhibited GLP-1 release and cAMP accumulation. AZ1729 was insensitive to pertussis toxin and OZITX, supporting atypical FFA2 signaling. Stimulation of FFA3 with AR420626 or the ketone body {beta}-hydroxybutyrate increased GLP-1 secretion from GLUTag cells, an effect that was not mediated by cAMP production. AR420626, but not {beta}-hydroxybutyrate increased intracellular calcium levels. ConclusionsOverall, activation of FFA2 inhibited secretory function in GLP-1-releasing enteroendocrine cells, whereas activation of FFA3 stimulated GLP-1 secretion via distinct intracellular signaling mechanisms. O_FIG O_LINKSMALLFIG WIDTH=184 HEIGHT=200 SRC="FIGDIR/small/708924v1_ufig1.gif" ALT="Figure 1"> View larger version (37K): org.highwire.dtl.DTLVardef@175dbaforg.highwire.dtl.DTLVardef@a9cc3eorg.highwire.dtl.DTLVardef@1a026e5org.highwire.dtl.DTLVardef@15997af_HPS_FORMAT_FIGEXP M_FIG Graphical Abstract C_FIG HighlightsO_LIExposure to physiological levels of SCFAs stimulates GLP-1 secretion from colonic EECs C_LIO_LIFFA2 and FFA3 regulate GLP-1 release via non-canonical signaling pathways C_LIO_LIKetone bodies activate SCFA receptors to differentially modulate GLP-1 levels C_LIO_LILigand bias enables nutrient-dependent tuning of EEC gut hormone secretion C_LI

BackgroundThis study aims to examine the independent relationships between individual components of metabolic syndrome (MetS) and two key clinical outcomes in patients with Crohns disease (CD): disease activity, as quantified by the Crohns Disease Activity Index (CDAI), and the occurrence of complications. MethodsThis retrospective cross-sectional study included 376 adults with newly diagnosed Crohns disease. Multiple linear regression was used to examine associations between metabolic parameters and CDAI scores, while multivariate logistic regression assessed links to complications. Analyses were also based on clinical CDAI cut-offs. Predictive nomograms were developed and internally validated via bootstrap resampling. ResultsMultiple linear regression indicated that higher CDAI scores were independently associated with lower BMI (B = -5.866, P < 0.001), lower HDL-C levels (B = -81.770, P < 0.001), higher triglycerides (B = 15.618, P = 0.001), and lower ESR (B = -0.375, P = 0.03). Multivariate logistic regression established low HDL-C (OR = 0.042, P < 0.001), low BMI (OR = 0.915, P = 0.034), and high triglycerides (OR = 1.792, P = 0.007) as significant independent risk factors for complications. The developed nomograms demonstrated strong predictive performance, with an adjusted R2 of 0.207 for the CDAI model and an AUC of 0.765 for the complication model. For both predictive tasks, the model incorporating separate TG and HDL-C measurements significantly outperformed the TG/HDL-C ratio model. ConclusionMetabolic disturbances demonstrate a significant association with increased disease severity and a higher risk of complication development in Crohns disease. Core tipO_LIDual-outcome study reveals HDL-C and TG differentially link to CD inflammation and complications, pointing to distinct mechanisms. C_LIO_LILow HDL-C is the strongest independent predictor for CD complications, underscoring its protective role beyond cholesterol transport. C_LIO_LIIndividual TG and HDL-C metrics outperform their ratio in prediction, challenging its use and suggesting independent pathways in CD. C_LIO_LILow BMI independently associates with both adverse outcomes, refining the "obesity paradox" and highlighting malnutritions key role. C_LIO_LIA practical, validated nomogram (AUC=0.765) integrates HDL-C, TG, and BMI to stratify complication risk, aiding clinical decision-making. C_LI

Type I interferons (IFN-Is) play a critical role in innate immunity, modulating the host response. While dysregulated IFN-I signaling has been implicated in autoimmune and infectious disorders, its role in inflammatory bowel disease (IBD) remains unclear. In this study, we extensively assessed the function of IFN-I signaling in human IBD and murine models of colitis. Expression of IFN-I signature genes was elevated in patients with active ulcerative colitis as well as multiple murine models of colitis. Single cell RNA sequencing revealed that upregulated IFN-I signature genes were enriched in myeloid cells, which exhibited increased expression of IFN receptors during mucosal inflammation. Mice carrying gain-of-function alleles of Ifnar1, a subunit of IFN-I receptor, showed heightened IFN-I signaling and altered colonic immune homeostasis at baseline, and were more susceptible to experimental colitis. In contrast, postnatal inhibition of IFNAR1, using either an inducible transgenic mouse model or an anti-IFNAR1 blocking antibody, protected against experimental colitis. Taken together, our findings reveal a previously under-recognized pathogenic role of IFN-I in IBD and provide a rationale for therapeutic intervention targeting this pathway.

Background and Aims: Alterations in immunoglobulin G (IgG) N-glycosylation are implicated in inflammatory bowel disease (IBD); however, the robustness of IgG glycan signatures across IBD cohorts with diverse demographics and geographic origins remains underexplored. We aimed to determine whether compositional data analysis (CoDA) and machine learning (ML) can identify IBD-related IgG N-glycan signatures and whether these signatures capture disease-associated acceleration of biological aging. Methods: We analyzed the IgG glycome profiles of 1,367 plasma samples collected from healthy controls (HC), symptomatic controls (SC), and people with newly diagnosed Crohn's (CD), and ulcerative colitis (UC) across four cohorts (UK, Italy, United States, and Netherlands). IgG glycosylation was analyzed by ultra-high-performance liquid chromatography, yielding 24 total-area-normalized glycan peaks (GPs). Analyses were performed using cross-sectional data obtained at baseline. CoDA-powered association analyses were used to identify disease-related effects on GPs while controlling for demographic covariates. ML models were trained and evaluated to assess generalizability to unseen cohorts and demographic subgroups, with a focus on discrimination and reliability. Results: Across all cohorts, people with IBD demonstrated accelerated biological aging as quantified by the GlycanAge index. This was accompanied by consistent reductions in IgG galactosylation, with effects partially modulated by age. Classification models trained on glycomics and demographics achieved robust discrimination (AUROC~0.80) between non-IBD (HC+SC) and IBD across cohorts. Conclusion: These findings reveal accelerated biological aging in people with IBD and support the translational potential of IgG glycans as biomarkers and a novel route toward clinically interpretable personalized risk estimates.

Background and AimsArtificial intelligence (AI) is increasingly applied to histological assessment in inflammatory bowel disease (IBD), but most approaches quantify features in isolation and ignore their anatomical location within the mucosa. We developed and validated PAIR-IBD (Perspectum AI Reading in IBD), an AI system that quantifies inflammatory cell populations, crypt injury, and epithelial damage within defined mucosal compartments to distinguish active disease, remission, and equivocal cases in ulcerative colitis (UC). MethodsA deep learning ensemble was trained on three IBD biopsy datasets to identify lymphocytes, neutrophils, eosinophils, and plasma cells, and to segment crypts, lamina propria (LP), and muscularis mucosae. Inflammatory cell densities and crypt injury metrics (mucin depletion, solidity, roughness, branching, and abscess formation) were quantified. PAIR-IBD outputs were compared between histologically active and remissive UC, evaluated in inconclusive cases, and correlated with manual pathology grading. ResultsNeutrophil density increased 3.5-fold in the LP and 15-fold within crypts in active UC (p<0.0001). Eosinophil density doubled and LP lymphocytes increased 1.4-fold. Active UC showed increased mucin depletion, crypt branching, and crypt abscesses, with reduced crypt solidity (p<0.0001 for all). PAIR-IBD metrics correlated with manual inflammatory and crypt injury scores (rs=0.23-0.72) and global indices (rs=0.27-0.65). Up to 89% of inconclusive cases aligned with remission-like profiles based on multiple independent AI metrics. ConclusionPAIR-IBD provides spatially resolved, quantitative assessment of inflammation and epithelial injury in UC, improving disease stratification and resolution of equivocal histology, with potential to support scoring consensus and improve accuracy of histological endpoints in clinical trials.