Introduction

Microscopic colitis (MC) is an inflammatory bowel disease (IBD) that causes chronic non-bloody watery diarrhea and abdominal pain that significantly reduces the quality of life¹. MC can be subdivided into collagenous colitis (CC) and lymphocytic colitis (LC), which are clinically indistinguishable but differ histologically². The activation of immune responses and the alteration of the intestinal epithelial barrier via water channel aquaporin downregulation and crypt hyperproliferation are characteristic features of MC³, often shared by other gastrointestinal disorders, such as “classical” IBD (Crohn’s disease and ulcerative colitis, UC), or irritable bowel syndrome (IBS). Enteric glial cells (EGC) are key regulators of gut homeostasis and epithelial permeability, that respond to inflammation by entering a reactive state, potentially driving epithelial dysfunction. Whether EGC promote resolution or perpetuate inflammation remains unclear.⁴

Aims & Methods

MC is poorly understood and EGC role in MC is still unknown. Therefore, our aim is to investigate the involvement of EGC – due to their neuroimmune functions and involvement in intestinal dysmotility – in patients with MC. In addition, mast cells will be investigated since altered interactions with EGC have been demonstrated during IBS⁵.
Paraffin-embedded colonic biopsies from patients with active CC, LC, UC, IBS-diarrhea (D) and healthy controls (HC) were collected (n=13-26 per cohort). In addition, a subset of CC patients was also sampled during successful treatment with glucocorticosteroid 9mg budesonide (n=13). The amount of EGC was quantified using glial fibrillary acidic protein (GFAP) and S100 calcium-binding protein B (S100β). Mast cells were quantified using tryptase.

Results

Immunofluorescence analysis of EGC revealed an increased amount of EGC^GFAP+ in CC compared to HC (p<0.001). Of note, CC EGC^GFAP+ levels were comparable to those shown by biopsies from patients suffering from IBS-D and UC. Among the 13 CC patients with paired samples before and under budesonide treatment, we observed a trend toward reduced EGC^GFAP+ levels during treatment (p = 0.08). In contrast, LC patients displayed similar EGC^GFAP+ levels as to HC, but lower than those observed in biopsies from patients with CC, IBS-D, and UC (p<0.001). On the other hand, EGC^S100β+ were increased only in active CC (p<0.0001). Yet, UC patients displayed the highest level of EGC^S100β+ (p<0.0001). Mast cells analysis showed an increased counts for tryptase in CC before and under treatment compared to HC (p<0.01).

Conclusion

Our findings indicate that EGC and mast cells are involved in CC pathogenesis due to an increased reactivity of EGC and mast cells in the colonic mucosa. CC patients exhibit signs of EGC^GFAP+ levels comparable to those observed in UC and IBS-D. Oppositely, LC seems to be independent of neuroinflammation as EGC and mast cells presence was comparable to HC. These preliminary findings support the theory that CC and LC are distinct disease entities. Future work will include RNA sequencing of EGC-related genes, counts of eosinophils as well as in situ analysis of mast cells and eosinophils degranulation, and assessment of budesonide effects on EGC in vitro.

References

1. Nyhlin N, Wickbom A, Montgomery SM, et al. Long-term prognosis of clinical symptoms and health-related quality of life in microscopic colitis: a case-control study. Aliment Pharmacol Ther 2014; 39: 963-972. 20140311. DOI: 10.1111/apt.12685.
2. Carrasco A, Esteve M, Salas A, et al. Immunological Differences between Lymphocytic and Collagenous Colitis. J Crohns Colitis 2016; 10: 1055-1066. 20160229. DOI: 10.1093/ecco-jcc/jjw058.
3. Escudero-Hernandez C, Munch A, Ostvik AE, et al. The Water Channel Aquaporin 8 is a Critical Regulator of Intestinal Fluid Homeostasis in Collagenous Colitis. J Crohns Colitis 2020; 14: 962-973. DOI: 10.1093/ecco-jcc/jjaa020.
4. Gonzales J and Gulbransen BD. The Physiology of Enteric Glia. Annu Rev Physiol 2024 20241115. DOI: 10.1146/annurev-physiol-022724-105016.
5. Meira de-Faria F, Casado-Bedmar M, Marten Lindqvist C, et al. Altered interaction between enteric glial cells and mast cells in the colon of women with irritable bowel syndrome. Neurogastroenterol Motil 2021; 33: e14130. 20210402. DOI: 10.1111/nmo.14130.

Introduction

There is evidence linking inflammatory bowel disease (IBD) and cardiovascular diseases. However, the roles of histologic and clinical activity of IBD in the development of arrhythmias remain unknown.

Aims & Methods

In this nationwide cohort study in Sweden, we included IBD patients with histologic data (n = 61,383; diagnosed 1969–2017; classified as histologic inflammation vs. remission based on the Swedish version of the Systematized Nomenclature of Medicine codes) and clinical activity data (n = 96,154; diagnosed 1969–2020; classified as clinically active vs. quiescent IBD based on IBD-related hospitalization, surgery, and treatment escalation) and followed them through December 31, 2021. The primary outcome was incident arrhythmias (including atrial fibrillation/flutter, bradyarrhythmias, other supraventricular arrhythmias, and ventricular arrhythmias/cardiac arrest) within 2 years after documented histologic inflammation (vs. remission) or clinically active IBD (vs. quiescent IBD). Poisson regression models estimated incidence rates (IRs) of arrhythmias, while Cox proportional hazards models estimated adjusted hazard ratios (aHRs) and 95% confidence intervals (CIs). We adjusted for age at IBD diagnosis, sex, calendar year at index date, county of residence, educational attainment, country of birth, number of health care visits, and history of CVD-related comorbidities in the model.

Results

Histologic inflammation was associated with an increased risk of developing any arrhythmias compared to histologic remission (IR: 62.0 vs. 47.2 per 10,000 person-years; aHR = 1.35, 95%CI: 1.18–1.54), corresponding to one additional event of arrhythmia per 338 IBD patients over 2 years after histologic inflammation. We found an excess risk for atrial fibrillation/flutter (aHR = 1.38, 95%CI: 1.18–1.62) and ventricular arrhythmias/cardiac arrest (aHR = 1.73, 95%CI: 1.22–2.44), but not for bradyarrhythmias or other supraventricular arrhythmias. Compared to clinically quiescent IBD, active IBD was also related to a higher risk of arrhythmias (IR: 67.4 vs. 108.4; aHR = 1.77, 95%CI: 1.66–1.88), affecting all subtypes except bradyarrhythmias. In patients with clinically quiescent IBD, histologic inflammation was also associated with an increased risk of arrhythmias (aHR = 1.16, 95%CI: 1.00–1.36, P=0.054).

Conclusion

Histologic and clinical activity were associated with a slightly increased risk of arrhythmias in patients with IBD.

Disclosure

All authors have completed the ICMJE uniform disclosure form and declare:
OO has been PI on projects at Karolinska Institutet financed by grants from Janssen, Pfizer, AbbVie, Takeda, Galapagos/Alfasigma, Ferring, and Bristol Myer Squibb. JH served as speaker or advisory board member for AbbVie, BMS, Celltrion, Eli Lilly, Ferring, Galapagos, Gilead, Index Pharma, Janssen, Medtronic, Merck, MSD, Novartis, Pfizer, Sandoz, Shire, Takeda, Thermo Fisher Scientific, Tillotts Pharma, and Vifor Pharma and received grant support from Takeda, Janssen, and MSD. FE has served as an advisory board member for Boehringer Ingelheim. JFL has coordinated a study for the Swedish IBD Quality Register (SWIBREG), which received funding from Janssen Corporation. JFL has also received financial support from MSD to develop a paper reviewing national healthcare registers in China. JFL has a research collaboration on celiac disease with Takeda and has a research collaboration on fibrosis in IBD with MSD. The other authors report no disclosures relevant to the manuscript.

Introduction

Increased mesenteric blood flow in inflammatory bowel disease (IBD) alters biomechanical forces acting on intestinal vascular endothelial cells (ECs). These cells sense mechanical stimuli through the mechanosensitive ion channel Piezo1, which transduces these forces into pro-inflammatory signaling, thereby aggravating inflammation. Moreover, lactate contributes to immune regulation by influencing macrophage polarization. However, the precise role of Piezo1 in governing endothelial lactate metabolism during IBD pathogenesis remains insufficiently understood.

Aims & Methods

To elucidate the role of Piezo1 in IBD, single-cell RNA sequencing was conducted on colonic tissues from IBD patients and healthy controls to evaluate Piezo1 expression and its association with lactate metabolism. Endothelial cell-specific Piezo1 knockout (Piezo1^ΔEC/ΔEC) mice were generated and subjected to DSS-induced colitis to assess inflammation severity, lactate levels, and macrophage polarization. CRISPR-Cas9 technology was employed to knock out Piezo1 in human umbilical vein endothelial cells (HUVECs). The involvement of the HIF-1α-mediated glycolysis pathway and monocarboxylate transporter 1 (MCT1) in Piezo1-dependent lactate regulation was also investigated.

Results

Piezo1 expression was significantly upregulated in intestinal ECs from active IBD patients and DSS-induced colitis mice compared to controls. Single-cell sequencing further confirmed the enrichment of Piezo1 in intestinal ECs during active inflammation. In DSS-induced colitis, Piezo1^ΔEC/ΔEC mice exhibited decreased levels of pro-inflammatory cytokines (IL-6, TNF-α, IL-1β), a reduced M1/M2 macrophage ratio, and lower lactate concentrations in both endothelial cells and plasma. Piezo1 activation promotes aerobic glycolysis through the Ca²⁺-induced CaMKII-HIF1α axis. Moreover, the Piezo1/HIF-1α pathway upregulated MCT1 expression in ECs, enhancing lactate transport across mesenteric vessels. Deletion of Piezo1 suppressed MCT1 expression, normalized plasma lactate levels, attenuated M1 macrophage activation, and ameliorated colitis severity in Piezo1^ΔEC/ΔEC mice.

Conclusion

These findings demonstrate that mechanical forces activate Piezo1 in intestinal ECs, driving lactate metabolism through the Piezo1-HIF-1α-MCT1 axis and promoting M1 macrophage differentiation, which subsequently contribute to intestinal inflammation in IBD. Targeting Piezo1 may represent a promising therapeutic strategy for the treatment of IBD.

Introduction

IIn Crohn’s disease, chronic inflammation drives fibroblast activation, excessive collagen deposition, and creeping fat expansion, all contributing to fibrostenotic strictures. We examined serum markers related to collagen formation, macrophage and neutrophil activation, and NETosis, exploring their associations with stricturing Crohn’s disease in a treatment-naïve IBD inception cohort.

Aims & Methods

142 Serum samples from CD patients were analysed (IBSEN III population matched baseline and 1-year follow-up). The Montreal classification (luminal, fibrostenotic strictures, fistula) was applied to assess disease complications at the time of serum sampling, e.g. baseline biomarkers measurements were paired with baseline Montreal B assessment, and one-year followup biomarkers measurements were paired with one-year followup Montreal B assessment. The biomarkers C4M, C6M, C7M, PRO-C3, PRO-C4, PRO-C5, PRO-C6, PRO-C11, PRO-C16, PRO-C22, VICM, CTX-III, CPa9-HNE were measured in the serum samples at baseline (total n=142; luminal n=114; fibrostenotic n=23, fistula n=5) and 1-year follow-up (total n=142; luminal n=111; fibrostenotic n=24, fistula n=7). One-way-ANOVA with LSD correction was applied for statistical analysis.

Results

The PRO-C6 (p<0.001) and CPa9-HNE (p<0.05) biomarkers were significantly elevated in CD patients with fibrostenotic strictures compared to luminal CD patients at baseline, and PRO-C6 was continually elevated in serum after 1 year of follow-up in patients with fibrostenotic strictures (p<0.01). At baseline, C7M was demonstrated to be elevated in fistulizing CD patients compared to luminal and fibrostenotic CD patients (P<0.01). PRO-C5 (p<0.001) and PRO-C16 (p<0.01) were significantly elevated at 1-year follow-up in the CD patients with fibrostenotic strictures compared with luminal CD patients. None of the remaining biomarkers were associated with stenotic or fistulizing CD.

Conclusion

These encouraging biomarker data from the IBSEN III, especially PRO-C6, seem to be a promising biomarker for intestinal fibrosis, as PRO-C6 was demonstrated to be elevated at baseline and after 1 year follow-up. CPa9-HNE levels were highest in the fibrostenotic group, suggesting neutrophil activity and NETosis involvement in intestinal fibrogenesis. Elevated levels of C7M were associated with fistula in CD patients, suggesting that C7M is reflective of transmural inflammation. The biomarkers PRO-C5 and PRO-C16 are also relevant biomarkers of established intestinal fibrosis, as these were elevated after 1 year of follow-up. Collectively, these biomarker data highlight the importance of quantifying collagen protein fragments in serum as tools for assessing intestinal fibrosis in Crohn’s disease.

Disclosure

Full time employee at Nordic Bioscience A/S

Introduction

The intestinal mucosa undergoes constant renewal, with epithelial and immune cells routinely shed into the gut lumen. Recent findings suggest that these shed cells remain viable and retain transcriptomic signatures relevant to bowel pathology. Analysis of luminal content obtained during colonoscopy indicates that Fecal Host Transcriptomes (FHT) mirror histologic inflammation in IBD. This study aimed to evaluate whether sequencing of stool samples can noninvasively reflect the presence of intestinal inflammation in patients with IBD, predict the location of inflammation within the bowel and distinguish between IBD type; Crohn’s Disease and Ulcerative Colitis.

Aims & Methods

Our aim was to investigate whether transcriptomic analysis of stool samples that are taken ambulatory or at home could reveal the inflammation signature of inflamed IBD patients.
Bulk RNA sequencing of stool samples from 71 IBD patients and healthy controls was used to generate FHTs. Each sample was paired with an endoscopic assessment and clinical data to capture a time-matched view of intestinal inflammation. Three random forest classifiers were trained to: (1) distinguish active inflammation from remission; (2) predict inflammation location in Crohn’s disease (colon vs. small intestine). and (3) classifier based on gene modules expression was used to differ between CD and UC in patients with active inflammation.

Results

Fecal RNA quality was high, with a median of 2,140 human genes detected per sample. The FHT test demonstrated robust performance across all tested applications. The first model, designed to distinguish active inflammation from remission (n = 71), achieved a sensitivity of 85% and a specificity of 92%. The second model, which predicted the location of inflammation in Crohn’s disease patients (n = 21), achieved 100% sensitivity and 100% specificity. The third model, aimed at differentiating Crohn’s Disease from Ulcerative Colitis (n = 35), reached a sensitivity of 83% and a specificity of 100%. These findings underscore the potential of FHTs as a non-invasive tool for comprehensive inflammation profiling in IBD.

Conclusion

Fecal shed cell transcriptomics offers a novel, non-invasive approach for assessing mucosal inflammation at the endoscopic level in IBD patients. This approach enables differentiation between disease activity states, anatomical localization of inflammation, and IBD subtype classification. Ongoing studies aim to evaluate its utility in grading inflammation severity and predicting therapeutic response.

References

Dan et al., CMGH 2023
Ungar et al., GUT 2022

Introduction

Tyrosine kinase 2 (TYK2) inhibitors block signaling downstream of multiple pro-inflammatory cytokines involved in immune-mediated inflammatory diseases, including inflammatory bowel disease, and may have an improved safety profile relative to Janus kinase inhibitors. Phase 2 studies of the highly selective and potent TYK2 inhibitor zasocitinib in Crohn’s disease (CD; NCT06233461) and ulcerative colitis (UC; NCT06254950) are ongoing.^1,2 Here, we describe the design of a combined open-label extension trial (NCT06764615), which will include patients from both parent trials who are responsive to treatment.

Aims & Methods

Patients are eligible for the phase 2 parent studies in CD and UC if they are aged 18–75 years with moderately to severely active disease, and have inadequate or loss of response to, or intolerance of, ≥ 1 standard or advanced therapy. Patients who have failed treatment with ≥ 3 classes of advanced therapy are excluded. Patients are randomized to one of three (CD) or two (UC) doses of zasocitinib, or placebo, for a 12-week double-blind induction phase followed by a 40-week sponsor-open (CD) or open-label (UC) maintenance period. At the end of the parent trials, patients will be eligible for the combined open-label extension if they are clinical (CD) or symptomatic (UC) responders at Week 52, defined as: (1) CD: a ≥ 30% decrease in average daily very soft or liquid stools and/or a ≥ 30% decrease in average daily abdominal pain from baseline; and (2) UC: a ≥ 1-point and ≥ 30% decrease from baseline in partial modified Mayo score, and a ≥ 1-point decrease from baseline in rectal bleeding (RB) subscore or achievement of an absolute RB subscore of ≤ 1. All enrolled patients will receive the same dose of open-label, oral, once-daily zasocitinib for a maximum of 108 weeks, with study visits every 12 weeks, followed by a 4-week safety follow-up period. Data analysis will be descriptive, with no formal statistical comparisons performed.

Results

The primary objective of the study is to determine long-term safety and tolerability, assessed through the incidence of treatment-emergent adverse events or adverse events of special interest. Secondary endpoints will assess the long-term efficacy of zasocitinib, including clinical, symptomatic, or endoscopic response or remission by visit or at Weeks 48 and 108, according to indication, and effects on patient-reported outcomes, including fatigue, bowel urgency, abdominal pain, and disease-specific health-related quality of life.

Conclusion

This open-label extension trial will provide data on the long-term safety of zasocitinib, as well as durability of treatment response among patients with CD or UC who experience treatment benefit in the phase 2 parent studies.

References

1. Jairath V et al. UEG Journal 2024;12(S8):1033.
2. Peyrin-Biroulet L et al. UEG Journal 2024;12(S8):1041.

Disclosure

GP reports receiving personal payments, honoraria, or speaker fees from AbbVie, Allergan, BMS, Celltrion, Ferring, Galapagos, Janssen, Pfizer, Sorriso, Takeda, and Tillotts, travel grants or fellowships from AbbVie, Celltrion, Ferring, Janssen, Takeda, and Tillotts, and is a Director and shareholder in Ampersand Health. SGR, LZ, VAN, LA, FN, TF, LS, and NS are employees and shareholders of Takeda.

Introduction

Hepatobiliary disorders are recognised extraintestinal manifestations in inflammatory bowel disease (IBD). Up to 30% of patients exhibit abnormal liver function tests and 5% will develop chronic liver disease (1). IBD-associated liver diseases (IBDALD), comprising primary sclerosing cholangitis (PSC), autoimmune hepatitis (AIH) and AIH/PSC overlap syndrome carry significant morbidity through progressive hepatobiliary damage and increased cancer risk. Early recognition is challenging due to non-specific biochemical derangement and heterogeneous presentation. No validated stratification tools exist for prospective risk identification. This study investigated whether routinely collected biomarkers convey predictive value for IBDALD, leveraging large-language model (LLM) refined phenotyping.

Aims & Methods

We analysed 1,571 paediatric and adult-onset IBD patients recruited to the “Genetics of IBD” study (Southampton, UK; 2010–). IBDALD cases were identified through LLM-assisted (Llama 3.1-70B-Instruct) structuring of 32,041 free-text imaging and histopathology reports, followed by clinician verification (2). Participants diagnosed with IBDALD prior to IBD were excluded from further analysis. Examined biomarkers included ALT, ALT and ESR (n=335,605 datapoints for the examined cohort). For each biomarker, patient-level medians were calculated from all available results within ±6 months of IBD diagnosis. A 1:4 individual matched case-control design was applied (matched on age at IBD diagnosis, gender, and IBD subtype) in R. Conditional logistic regression models assessed associations between IBDALD and biomarker values, treated as both continuous (patient-level medians) and binary – normal versus abnormal - (age- and sex-adjusted lab range flags) variables. Longitudinal biomarker trajectories were explored using LOESS and linear mixed-effects models.

Results

Thirty-five cases of IBDALD were identified (27 post-IBD diagnosis). Median follow-up duration was 11.5 (0.5–59.5) years and median 4.5 years (0.4–39.1) from IBD diagnosis to liver disease onset. In whole cohort analyses, ALT, ALP, and ESR were significantly elevated in IBDALD at diagnosis of IBD (p < 0.01). In matched case-control models, higher median ALT (OR = 1.04 per U/L increase, 95% CI: 1.01–1.07, p = 0.012), ALP (OR = 1.01, 95% CI: 1.00–1.02, p = 0.014), and ESR (OR = 1.05, 95% CI: 1.00–1.09, p = 0.034) were each associated with IBDALD. In a combined model including all three biomarkers, none retained statistical significance. When analysed as binary (normal/abnormal) variables, ALT and ALP remained significantly associated with IBDALD (ALT: OR = 5.10, 95% CI: 1.57–16.59, p<0.01; ALP: OR = 15.33, 95% CI: 1.87–125.77, p<0.05). ESR did not reach significance (OR = 3.71, 95% CI: 0.75-18.32 p=0.107). Longitudinal modelling supported distinct ALT and ALP trajectories in the IBDALD group and distinct trends over time were visualised for ALT, ALP and ESR in LOESS scatterplots.

Conclusion

These data suggest that routinely measured biomarkers may carry early predictive signals for IBD-associated liver disease, identifiable at the time of IBD diagnosis. The use of LLM-assisted phenotyping enabled high-fidelity case definition within real-world data. These findings should be interpreted cautiously given the rarity of IBDALD and potential overfitting in multivariable models. Future prospective studies are warranted to validate predictive models and support integration into IBD care pathways.

References

1. Scott JA, Mysko C, Purssell H, et al. Investigation of abnormal liver blood tests in patients with inflammatory bowel disease. Frontline Gastroenterology 2024;15:516-522.
2. Kadhim A, Green Z, Nazari I, et al. Application of Generative Artificial Intelligence to Utilise Unstructured Clinical Data for Acceleration of Inflammatory Bowel Disease Research. Article in PrePrint medRxiv 2025.03.07.25323569; doi: https://doi.org/10.1101/2025.03.07.25323569

Disclosure

JJA is a SAB member for Orchard Therapeutics.