Introduction

Tryptophan metabolism is severely disrupted in IBD. Pro-inflammatory cytokines activate the first rate-limiting enzyme IDO1 leading to tryptophan degradation through the kynurenine pathway. Although Trp degradation typically support de novo NAD synthesis via KP activation, evidence suggests a metabolic block at the downstream enzyme QPRT in IBD. STING has been described as inducing the secretion of type I interferons and other inflammatory cytokines, suggesting its important role in regulating intestinal homeostasis. Several studies have reported an association between STING-mediated IDO1 activity and its role in promoting tumour immune evasion. However, the relationship between STING pathway and tryptophan metabolism in intestine has not be understood. This study aims to investigate the effect of STING signalling on tryptophan degradation and explore how the metabolic blockage in tryptophan-NAD axis may influence STING-mediated immune response.

Aims & Methods

To investigate the STING pathway's role in tryptophan metabolism within the intestinal microenvironment, we utilized human colonic fibroblast cell line CCD-18co. Quantitative RT-PCR and Western blot were employed to measure mRNA and protein expression. Tryptophan metabolism was quantified via LC-MS. QPRT knockdown was achieved using siRNA transfection. Transcriptomic changes were analysed by RNA sequencing. Intracellular NAD level were assessed by NAD-Glo assay. Seahorse assay was conducted to evaluate mitochondrial function.

Results

We screened a range of established IDO1-inducing cytokines (IFNγ, TNFα, etc.) and compared their effects on IDO1 expression with STING agonists diABZI, dsDNA and 2'3'cGAMP. STING agonists induced significantly higher IDO1 expression than any of the cytokines tested. While cultivation of in presence of Anifrolumab (type I IFN receptor antagonist) and Tofacitinib (pan-JAK inhibitor) strongly inhibited STING-induced IDO1 upregulation. LC-MS showed upregulation of IDO1 drive tryptophan into kynurenine pathway, which was again inhibited by Anifrolumab and Tofacitinib.
To mimic the reduced QPRT expression in IBD, we performed QPRT knockdown followed by RNA sequencing. Loss of QPRT resulted in spontaneous activation of type I interferon signature, which was further amplified upon stimulation with STING agonists, leading to a pronounced inflammatory transcriptional response. Mechanistically, QPRT-deficient cells exhibited reduced intracellular NAD levels and signs of mitochondrial dysfunction, including opening of the mitochondrial permeability transition pore (mPTP), release of mitochondrial DNA and RNA into the cytosol, and subsequent activation of the cGAS-STING and RIG-I/MAVS pathways, respectively. These events collectively led to a pronounced induction of type I interferons and pro-inflammatory cytokines. Notably, supplementation with nicotinamide riboside (NR) restored intracellular NAD levels and significantly attenuated the heightened inflammatory response induced by QPRT knockdown.

Conclusion

Our findings reveal a novel mechanism by which STING activation in intestinal fibroblasts promotes tryptophan metabolism via kynurenine pathway. Furthermore, QPRT deficiency-induced metabolic disruption amplifies STING-mediated pro-inflammatory responses via the release of mitochondrial nucleic acids, a process that can be effectively attenuated by supplementation with NAD precursors.

Introduction

Dutch society has witnessed significant societal and demographic changes over the decades. With 28% of the Dutch population having a migration background in 2023, understanding diversity within the gastroenterology workforce is imperative. This study examines the evolution of sex, ethnic, and socio-economic diversity among Dutch gastroenterologists from 2005-2023.

Aims & Methods

This repeated cross-sectional study utilized pseudonymized data from the BIG-register, paired with demographic variables from Statistics Netherlands (CBS), covering the years 2005, 2010, 2015, 2020, and 2023. The total population sample in each year consisted of all individuals registered as gastroenterologists for at least one day in a respective year. Variables such as sex, migration background, year of birth, and parental socio-economic status indicators were analyzed to assess trends and identify factors associated with being a
gastroenterologist. Descriptive and logistic regression analyses were employed to explore these trends and compare generational differences.

Results

The study revealed a narrowing sex gap with an increase in female gastroenterologists (28% to 43% from 2005-2023), particularly among the younger cohort (60% female). However, ethnic diversity has not kept pace, with a decline in the representation of gastroenterologists from migration backgrounds among younger professionals (27% to 18% for gastroenterologists < 1979 and ≥ 1980, respectively). Socio-economic analysis indicated that approximately 75% of gastroenterologists have parents from top-20% assets category.

Conclusion

The gastroenterology field in the Netherlands shows significant advancements in gender diversity, but lags in ethnic and socio-economic diversity. The increasing trend of gastroenterologists from medical families highlights the need for policy adjustments, to ensure access to candidates from more diverse socio-economic backgrounds. Policies should focus much more on promoting comprehensive diversity to enhance healthcare outcomes and reflect the demographic changes within society.

References

1. Stanford FC. The Importance of Diversity and Inclusion in the Healthcare Workforce.
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2. Gomez LE, Bernet P. Diversity improves performance and outcomes. J Natl Med
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3. Juch A. 100 jaar Maag-Darm-Leverarts in Nederland 1913-20132013. 336 p.
4. Brach C, Fraser I. Reducing disparities through culturally competent health care: an
analysis of the business case. Qual Manag Health Care. 2002;10(4):15-28.
5. Moberly T. Men outnumber women three to one in some specialties. Bmj.
2018;363:k4098.
6. Subramaniam M, Azad N, Wasan SK, Long MT. Equal Opportunity: Women
Representation on Editorial Boards and Authorship of Editorials in Gastroenterology and
Hepatology Journals. Am J Gastroenterol. 2021;116(3):613-6.
7. Dossa F, Baxter NN. The place of women in gastrointestinal medicine and surgery:
the need for progress. Lancet Gastroenterol Hepatol. 2023;8(11):965-6.
8. Kesavarapu K, Schwartz J, Ikonomi E, Ahmad A. What's holding women back? A
review of gender inequality in gastroenterology in the USA. Lancet Gastroenterol Hepatol.
2019;4(12):898-900.
9. Esposito I, Simsek C, Nowak A, Tiniakos D, Equality UEG, Diversity G. United
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2023;11(5):484-7.

Disclosure

OKB, ABB, PK and LM have no conflict of interests, CJJM is consultant for Douglas (New Zealand) and HLW (The Netherlands). All outside submitted work.

Introduction

The BIOSTOP trial is a Norwegian, multicenter study with a prospective, randomized, controlled, and open-label design. The trial was initiated to evaluate the two-year outcomes following the withdrawal of tumor necrosis factor-alpha (anti-TNF) antibodies in patients with ulcerative colitis (UC) who are in sustained clinical and endoscopic remission.

Aims & Methods

The main aim was to identify transcriptomic differences in colon biopsies associated with increased risk of relapse with anti-TNF withdrawal. We also wanted to increase our understanding of the underlying pathological mechanisms of relapse after anti-TNF withdrawal and treatment failure during continued treatment.
Between June 2017 and December 2020, 174 ulcerative colitis patients in confirmed clinical and endoscopic remission were enrolled and randomized, with 86 assigned to continue anti-TNF therapy (control group) and 86 to discontinue treatment (intervention group). Mucosal biopsies were collected at baseline, two-year follow-up, and at point of relaps
Bulk mRNA-sequencing was performed on RNA extracted from rectal biopsies. For patients in remission, samples from baseline and two-year follow-up were analyzed. For those who relapsed or experienced treatment failure, samples from baseline and point of relapse were analyzed. Differential gene expression was performed using DESeq2, and pathway enrichment analysis was assessed with clusterProfiler.

Results

There were no significant differences found at baseline between patients that relapsed (n=45) vs those that stayed in remission (n=41) after anti-TNF withdrawal. In patients that relapsed, the comparison from baseline to point of relapse showed upregulation of key inflammatory genes, including IL1B, STAT3, OSMR, TNF and CXCL10. Pathway enrichment analysis showed that the upregulated genes were associated with an inflammatory response, including TNF-signaling. At two-year follow-up patients who remained in remission also showed upregulation of proinflammatory genes, including genes associated with TNF-signaling. However, the expression levels were lower than in the relapse group. Patients in the control group who experienced treatment failure (n=10) showed a gene expression signature that strongly overlapped with those that relapsed in the intervention group.

Conclusion

We did not detect any transcriptional differences between the relapse and remission group at baseline and after anti-TNF withdrawal the expression of proinflammatory genes including genes involved in TNF-signaling increased in both groups. However, a more pronounced increase was observed in the relapse group, suggesting that those that relapse exhibited reduced immunoregulatory capacity.

Introduction

The Pisa EoE Adaptation Questionnaire (PiEAQ) on adaptive behaviors at mealtime significantly improves the correlation between dysphagia scores and histological disease activity (HDA) in eosinophilic esophagitis (EoE) [Reference 1].

Aims & Methods

Whether longitudinal variations of PiEAQ scores (∆PiEAQ) can capture HDA trends following pharmacological treatment of EoE has not been investigated. Consecutive adults (>18 years) with histologically active EoE (i.e., ≥15 eos/high-power field) were prospectively enrolled. Clinical characteristics, HDA, a recall-modified dysphagia symptom questionnaire (mDSQ), esophageal hypervigilance and anxiety scale (EHAS), and PiEAQ (drinking water to push the bolus, lubricating food, chewing for long, and blending food) were recorded longitudinally at baseline (T0) and 12 weeks post-treatment using a 30-day recall period (T1). ROC curve analysis with DeLong test was used to calculate the diagnostic accuracy (AUC) of clinical scores for predicting HDA following treatment. Significance threshold was p<0.05.

Results

Thirty-seven histologically active EoE patients were included (Table 1). The mDSQ, PiEAQ, and EHAS score at baseline were 2.97 (IQR, 2-5), 2.00 (IQR, 1-3), and 21 (IQR, 14– 25), respectively. Following treatment with budesonide orodispersible tablets (72.2%), PPIs (19.6%), dupilumab (5.5%), or milk-free diet (2.7%), histological remission was achieved in 78.4% of patients, while 21.6% remained histologically active. Post-treatment (T1), mDSQ, PiEAQ, and EHAS scores decreased significantly only in patients who achieved histological remission (Table 2 and Figure1). ROC curve analysis showed that a post-treatment reduction of at least 2 adaptive behaviors compared to baseline (∆PiEAQ=-2) had AUC of 85.0%, with 100% specificity and 64% sensitivity for the identification of patients achieving histological remission following treatment. Similarly, a post-treatment reduction of at least 3 points in mDSQ scores compared to baseline (∆mDSQ=-3) had AUC of 81.1% with 100% specificity and 57.7% sensitivity. The non-inferiority analysis showed that the ∆PiEAQ had similar performance to ∆DSQ (DeLong p-value= 0.46). A combined score integrating both ∆PiEAQ and ∆DSQ scores increased the AUC of clinical scores for capturing variations of HDA post-treatment to 90%, with 100% specificity and 73.1% sensitivity for detecting patients achieving histological remission post-treatment (Figure 2).

Conclusion

The PiEAQ is the first questionnaire investigating adaptive behaviors as a standalone domain in EoE. We demonstrated that longitudinal variations in PiEAQ scores are sensitive to HDA variations over time and can monitor histological disease activity trends after treatment. This study confirms that, similar to dysphagia, adaptive behaviors contribute to disease burden in EoE and improve with treatment.

References

1. Visaggi P, Del Corso G, Solinas I, Ovidi F, Adamo G, Dulmin I, Baiano Svizzero F, Bellini M, Savarino EV, de Bortoli N. Adaptive Behaviors, Esophageal Anxiety, and Hypervigilance Modify the Association Between Dysphagia Perception and Histological Disease Activity in Eosinophilic Esophagitis. Am J Gastroenterol. 2024 Dec 30. doi: 10.14309/ajg.0000000000003272. Epub ahead of print. PMID: 39787341.

Disclosure

Speaker or Consultancy for Apogee Therapeutics, Dr Falk Pharma, Malesci, JB Pharmaceuticals, Sanofi, Alfasigma

Introduction

Crohn ‘s disease (CD) is characterized by chronic inflammation in the gut, where severe complications such as fibrotic strictures require surgical resection. Stricture development involves excessive extracellular matrix (ECM) deposition due to continuous activation of intestinal myofibroblasts, that further contribute to intestinal fibrogenesis. Emerging data suggests that stricture-related intestinal myofibroblasts overexpress a serine protease called fibroblast activation protein (FAP). Furthermore, type III collagen deposition is increased during fibrosis in all layers of the intestinal tract, and studies have shown elevated collagen degradation in serum from patients with CD. The present study aimed at evaluating the potential of FAP-cleaved type III collagen [C3F] as a serum marker for intestinal fibrosis in CD.

Aims & Methods

The cohort consisted of 49 patients with luminal CD and 62 patients with stenotic CD. Clinical assessment was conducted for all patients at baseline and 12 months post study initiation. For the luminal phenotype, endoscopy was performed at both time points. For the stenotic group, radiographical assessment was done prior to surgery and endoscopy was performed at 12 months. C3F was measured in serum at all timepoints for baseline, post-operative day (POD), 1, 3, 6 and 12 months. To compare C3F levels at baseline for luminal vs stenotic phenotype, Mann-Whitney U-test was conducted. For the stenotic group, mixed-effect analysis, with a Dunnett’s multiple comparison applying Bonferroni Correction, was conducted to compare C3F levels for baseline vs POD and Spearman’s rank correlation was applied.

Results

C3F baseline levels were significantly higher in patients with stenotic CD compared to luminal CD (Table 1). In the stenotic group, C3F was significantly increased in patients at POD compared to baseline (Table 1). In the luminal group, C3F was significantly elevated in patients at 12 months compared to baseline. Furthermore, C3F showed a positive correlation with C-reactive protein (CRP) (ρ=0.350, p=0.006) and a significant negative correlation with disease duration (ρ= -0.257, p=0.048) for patients with the stenotic CD phenotype (Table 1).


Table 1. C3F levels are elevated in the stenotic CD vs the luminal CD group, with increased levels at POD compared to baseline for the stenotic phenotype. Spearman’s rank correlation, depicting the relationship between C3F and routine blood demographics, as well as demographics. Significant findings (p<0.05) are highlighted in bold.

Conclusion

C3F was elevated in patients with stenotic CD, with even higher levels after the surgical resection. The data suggests that C3F reflects fibroblast activity during fibrostenosis and tissue remodeling following surgery. The positive correlation with CRP supports the association with inflammation leading to collagen deposition and fibrosis. Interestingly, C3F shows negative correlation with disease duration suggesting that C3F could reflect fibrosis at early stages of stenotic CD. These findings highlight the potential use of C3F as a novel biomarker for intestinal fibrosis in CD.

Disclosure

TTK, MSA, MP are employed at Nordic Bioscience. ACBJ, JHM and MAK are employees and stock owners at Nordic Bioscience.

Introduction

While ileocecal resection (ICR) is the most common surgical procedure in Crohn's disease (CD), non-ICR surgeries account for only 20% of cases and remain underrepresented in the literature. This study aimed to identify specific clinical risk factors for surgical recurrence in CD patients undergoing small bowel or colonic resections without involving the ileocecal valve.

Aims & Methods

This multicenter retrospective cohort study included 257 patients with CD (124 small bowel resections, 133 colonic resections) across 13 Italian centers from 1978 to 2023. Univariate and multivariate logistic regression and Cox proportional hazards analyses were performed to identify clinical risk factors associated with surgical recurrence.

Results

The cohort comprised two distinct groups: small bowel resections (n=124), characterized by male predominance (63.71%), a high prevalence of stricturing disease (60.48%), and a median follow-up of 75.5 months; and colonic resections (n=133), featuring a more balanced gender distribution (47.37% male), higher rates of penetrating disease (47.37%), and a median follow-up of 88.0 months. Penetrating disease behaviour emerged as the only significant predictor of recurrence in logistic regression analysis (OR 2.16, 95% CI 1.03-4.52, p=0.041), while factors typically predictive in ICR, such as smoking (OR 0.90, p=0.843) and prior resections (OR 0.96, p=0.913), were non-significant. Cox regression identified prior biologic exposure as a significant predictor of earlier recurrence (HR 2.52, 95% CI 1.22-5.18, p=0.012), with TNF experience specifically associated with increased risk (HR 2.28, 95% CI 1.12-4.67, p=0.024). The cumulative number of risk factors (HR 1.35, 95% CI 1.01-1.82, p=0.046) and postoperative intra-abdominal septic complications (HR 2.75, 95% CI 1.18-6.44, p=0.020) also contributed to recurrence risk. Disease phenotypes significantly differed between resection types (p<0.001), with stricturing disease most prevalent in small bowel resections (60.48% vs. 36.09% in colonic) and penetrating disease more common in colonic resections (47.37% vs. 36.29% in small bowel). Results are summarized in Table 1.

Table 1: Univariate logistic regression analysis of predictors for postoperative surgical recurrence in patients undergoing small bowel or colonic resections. Abbreviations: CI: Confidence Interval; CD: Crohn’s Disease; IBD: Inflammatory Bowel Disease; POR: Postoperative recurrence; TNF: Tumour Necrosis Factors.

Conclusion

This study reveals distinct risk factors for surgical recurrence after non-ICR surgeries in CD. Unlike ICR where smoking, perianal disease, and prior resections predominate, non-ICR recurrence is primarily associated with penetrating disease phenotype and prior biologic exposure. These findings demonstrate that risk stratification models developed for ICR are not applicable to non-ICR surgeries, highlighting the need for procedure-specific approaches to postoperative management. Tailored prophylactic strategies should address the unique recurrence dynamics of small bowel and colonic resection surgeries.

Introduction

Infiltration of neutrophils into the intestinal tissue is a crucial component of the inflammatory response in Crohn‘s disease (CD). CPa9-HNE, a calprotectin fragment released by human neutrophil elastase during NETosis, has been shown to strongly correlate with endoscopic disease activity in inflammatory bowel disease (IBD) and serves as an indicator for pharmacodynamic response. Furthermore, emerging data suggests that neutrophil extracellular traps (NETs) significantly contribute to the pathogenesis of fibrosis.

Aims & Methods

For the first time, we investigated the association of CPa9-HNE with histological grading of both inflammation and fibrosis. The cohort included 62 patients with stenotic Crohn‘s disease. Inclusion criterion was the presence of stenotic disease requiring bowel resection, as confirmed by radiographic assessment. Upon surgery, the resected specimens were collected and histologically graded according to transmural fibrosis burden, and inflammation (D'Haens score). Serum was drawn at baseline (before resection). CPa9-HNE was measured, reflecting a human neutrophil elastase-derived fragment of calprotectin. Spearman’s rank correlation was applied.

Results

CPa9-HNE showed an overall positive correlation to the D'Haens score (ρ=0.279, p<0.005). Significant positive correlation was observed between CPa9-HNE and the presence of neutrophils, both in the epithelium and the lamina propria (ρ=0.309, ρ=0.349, p<0.005 both), as well as with epithelial damage (ρ=0.262, p<0.005). We also observed a positive correlation between CPa9-HNE and transmural fibrosis burden, specifically fibrosis in the submucosa (ρ=0.294, p<0.005)

Conclusion

This study showed that CPa9-HNE, a biomarker of neutrophil activity, correlated with the presence of neutrophils in the intestinal tissue, as well as epithelial damage. Interestingly, CPa9-HNE also showed association to submucosal fibrosis, emphasizing the importance of considering neutrophil activity when targeting the fibro-inflammatory axis. These findings highlight the potential use of CPa9-HNE as a complementary tool for histological grading of inflammation and fibrosis burden, and could be used to further explore the role of neutrophil extracellular traps in intestinal fibrosis.

Disclosure

MSA, TKA, MP, MAK, ACBJ and JHM are employees of Nordic Bioscience. MAK, ACBJ and JHM are shareholders of Nordic Bioscience.