Introduction

The highest risk factor of inflammatory bowel disease (IBD) is having a first-degree relative (FDR) with IBD. However, genetic variation accounts for only a small proportion of IBD heritability. Evidence from family and twin studies underscores the role of shared environment for the development of IBD. In a recent study based on two population-based IBD cohorts from South-Eastern Norway, thirty years apart, we reported a substantial increase in the rate of familial IBD (1).

Aims & Methods

This study investigates the potential underlying mechanisms for the increased rate of familial IBD in South-Eastern Norway.
We examine the association between shared environment and gene expression across IBD phenotypes [Crohn’s disease (CD) and ulcerative colitis (UC)] and four comparison groups: (I) multiplex IBD familial patients (≥3 FDRs with IBD), (II) healthy relatives in multiplex IBD families, (III) sporadic IBD patients, and (IV) symptomatic non-IBD controls. Expression analyses focus on four candidate genes, FKBP5, BCL3, VMP1, and TRAIL, previously identified as differentially methylated in IBD compared to controls (2,3). Blood samples were collected from 15 multiplex IBD families in South-Eastern Norway, between April 2023 and January 2024. For comparison, blood samples from 50 sporadic IBD patients and 50 symptomatic controls (SC) were obtained from the IBSEN III cohort (4).
RNA was extracted from PAXgene blood samples of the multiplex families at EpiGen, Akershus University Hospital, Norway, while RNA extractions from the sporadic IBD patients and SCs were performed at The Institute of Clinical Molecular Biology, Kiel, Germany. All cDNA synthesis were carried out at EpiGen. Gene expression was measured using RT-qPCR on cDNA with target-specific primers. Relative quantification was performed using GAPDH and ACTB as housekeeping genes.
Simple t-tests were conducted to compare the mean gene expression between the four comparison groups and across IBD phenotypes.

Results

The multiplex IBD family study included 62 individuals, 41 IBD patients, 25 patients with UC, 16 with CD, and 21 healthy family members, 13 FDR and 8 spouses. The results for the differences in mean fold changes between the four groups, including CD and UC for each of the four candidate genes, are presented in Table 1. The gene expression analysis revealed differences in mean fold changes between the four groups and across CD and UC.
The relative quantification of gene expressions for the four candidate genes revealed no significant differences in gene expression among the IBD patients vs healthy members of multiplex families.
Significant differences were observed for all candidate genes among familial IBD vs sporadic IBD and between healthy multiplex family members vs symptomatic controls, except for BCL3 and TRAIL, respectively. (p<0.005).

Conclusion

Our results reveal associations between the expression levels of IBD candidate genes and shared family environment, suggesting that epigenetic mechanisms may contribute to the development of familial IBD. Further methylation studies are warranted to clarify the underlying mechanisms of changed gene expression.

References

1. Aabrekk TB. Increased familial risk of IBD over thirty years based on twopulation-based IBD incident cohorts conducted in South-Eastern Norway in 1990-1994 (IBSEN I) and in 2017-2019 (IBSEN III). [Abstract]. In press 2024.
2. Ventham NT, Kennedy NA, Adams AT, Kalla R, Heath S, O'Leary KR, et al. Integrative epigenome-wide analysis demonstrates that DNA methylation may mediate genetic risk in inflammatory bowel disease. Nat Commun. 2016;7:13507.
3. Joustra V, Hageman IL, Satsangi J, Adams A, Ventham NT, de Jonge WJ, et al. Systematic Review and Meta-analysis of Peripheral Blood DNA Methylation Studies in Inflammatory Bowel Disease. J Crohns Colitis. 2023;17(2):185-98.
4. Kristensen VA, Opheim R, Perminow G, Huppertz-Hauss G, Detlie TE, Lund C, et al. Inflammatory bowel disease in South-Eastern Norway III (IBSEN III): a new population-based inception cohort study from South-Eastern Norway. Scand J Gastroenterol. 2021;56(8):899-905.

Disclosure

Vendel A. Kristensen har reported scientific advisory boards from Takeda AS, consultant fees from Janssen-Cilag AS and speaker fees from Thermo Fisher Scientific.
Marte Lie Høivik has reported investigator-initiated research grants from Takeda, Pfizer, Tillotts, Ferring and Janssen. Speaker honoraria from Takeda, Tillotts, Ferring, AbbVie, Pfizer, Galapagos, MSD and Meda and Advisory board Takeda, Galapagos, MSD, Lilly, Janssen, Pfizer and AbbVie.
The other authors of this abstract have no Conflict of Interest

Introduction

Metabolic dysfunction-associated steatotic liver disease (MASLD), formerly referred to as non-alcoholic fatty liver disease (NAFLD), and dyslipidemia are among the most common metabolic disorders worldwide. Disruption of intestinal barrier integrity, as reflected by elevated zonulin levels, has been implicated in insulin resistance and lipid metabolism disorders, contributing to the pathogenesis of MASLD.

Aims & Methods

The aim was to evaluate fecal zonulin levels in patients with dyslipidemia and MASLD, and to explore their potential role as risk factors for disease development and progression. The study included 342 patients with dyslipidemia, among whom MASLD was diagnosed in 152 cases based on ultrasound and steatometry findings. Fecal zonulin levels were measured by ELISA. Small intestinal bacterial overgrowth (SIBO) was diagnosed using hydrogen breath testing. Correlations between zonulin, inflammatory markers (high-sensitivity C-reactive protein, hsCRP), lipid profiles, and SIBO prevalence were analyzed.

Results

SIBO was detected in 45% of patients with dyslipidemia and 53.2% of patients with MASLD. Fecal zonulin levels in patients with MASLD (115±2.76 ng/g) significantly exceeded the normal upper limit (≤107 ng/g) and were higher compared to patients without steatosis. Zonulin levels positively correlated with hsCRP (r=0.65, p<0.05) and triglycerides (r=0.58, p<0.05). A strong negative correlation was observed between SIBO presence and HDL-C levels (r=–0.78, p<0.05) in patients with dyslipidemia.

Conclusion

Elevated zonulin levels and increased intestinal permeability are closely associated with systemic inflammation and lipid metabolism disturbances in MASLD. Zonulin and SIBO may represent novel therapeutic targets for the prevention and treatment of MASLD and metabolic disorders.

Introduction

Anti-mitochondrial antibodies (AMA) are commonly associated with Primary Biliary Cholangitis (PBC), a progressive liver disease. However, the clinical significance of AMA positivity in patients with normal liver enzymes remains poorly understood. Despite the presence of AMA, many patients maintain normal liver function, raising the question of whether these individuals are at risk for developing liver-related complications.

Aims & Methods

This study aims to evaluate the natural history, prognostic implications, and potential risk factors for disease progression in AMA-positive patients with normal liver enzymes.
A retrospective cohort study was conducted using a national healthcare database to identify patients (aged>18) with a positive AMA and normal liver enzymes between 2002 and 2023. Demographics, biochemical parameters, and liver-related complications were analyzed. Multivariate regression models assessed predictors of disease progression.

Results

Among 1,018 patients, 76 (7.5 %) developed Primary biliary cholangitis (PBC), and 30 (2.9%) progressed to cirrhosis over a median follow-up of 6.3 years. Liver-related complications were rare, with esophageal varices in 1.1%, ascites in 1.8%, hepatocellular carcinoma in 0.2%, and liver transplantation in 0.1%. Notably, higher AMA titers were strongly associated with increased risk of developing PBC, cirrhosis and liver-related complications, demonstrating a clear titer-dependent pattern.

Conclusion

Most AMA-positive patients with normal liver enzymes do not develop clinically significant liver disease. However, higher AMA titers identify a high-risk subgroup that warrants closer monitoring. These findings underscore the need for risk-stratified follow-up strategies and may influence future clinical guidelines.

Introduction

Functional dyspepsia (FD) and irritable bowel syndrome (IBS) are disorders that affect approximately 20% of the population. One of the proposed pathophysiological mechanisms in these conditions is a loss of mucosal integrity, associated with low-grade inflammation and food-induced mast cell activation. To date, confocal laser endomicroscopy to monitor allergy-like reactions to luminal food protein application, or a wheal-and-flare-like reaction to submucosal injection of food proteins have experimentally been used to demonstrate allergy-like food responses in these patients. Compared to these complex methods, urinary histamine measurement may provide an elegant and non-invasive tool to detect such food reactions in FD and IBS. In this pilot project we assessed the ability to detect an increase of urinary histamine and n-methylhistamine after ingestion of food with different histamine content.

Aims & Methods

Healthy volunteers were recruited to ingest a histamine rich meal (HRM) or low histamine meal (LHM) on two different days with one week in between, in a cross over fashion. All volunteers filled out the upper gastrointestial ROME-IV diagnostic questionnaire to confirm the absence of disorders of gut-brain interaction. Volunteers came to the hospital fasted and received a standardized breakfast (pancake, brown sugar, water). After two hours participants were asked to empty the bladder before they consumed the study meal. After finishing the meal participants collected all urine and filled out symptom questionnaires of 10 gastrointestinal symptoms (VAS 0-4) for 4 hours. ELISA analysis of urinary histamine and n-methylhistamine were performed in accordance with the manufacturer’s instructions. Data are shown as mean ± standard deviation. Statistical tests were done using a paired T-test or two-way ANOVA with correction for multiple testing as appropriate.

Results

We recruited 10 healthy volunteers (70% female) with an average age of 23,8 ± 5,05 years and an average body mass index (BMI) of 21,3±1,55. All participants finished the whole meal. Urinary output was similar after the HRM and LHM (respectively 577±167 mL and 540±128 mL, p=0,605). There was no difference in urinary n-methylhistamine excretion between the HRM and LHM (respectively 34,5±8,8 µg/g creatinine vs 36,3±10,3 µg/g creatinine, p=0,779). Urinary excretion measures of histamine were below the detection limit in the majority of samples, excluding this aspect from statistical analysis. Overall symptom scores did not differ significantly after the HRM and the LHM. Only at 15 minutes postprandially, higher scores were found for postprandial fullness after the HRM (mean difference of 0,4 [95% CI 0,01 – 0,79], p=0,038).

Conclusion

In healthy volunteers administration of food with high histamine content compared to food with low histamine content does not increase urinary n-methylhistamine excretion. Ingestion of a histamine rich meal was associated with a transient postprandial increase of excessive postprandial fullness and did not induce a significant rise in postprandial symptoms.

References

1: Vanheel H, Vicario M, Vanuytsel T, Van Oudenhove L, Martinez C, Keita ÅV, Pardon N, Santos J, Söderholm JD, Tack J, Farré R. Impaired duodenal mucosal integrity and low-grade inflammation in functional dyspepsia. Gut. 2014 Feb;63(2):262-71.
2: McIntosh K, Reed DE, Schneider T, Dang F, Keshteli AH, De Palma G, Madsen K, Bercik P, Vanner S. FODMAPs alter symptoms and the metabolome of patients with IBS: a randomised controlled trial. Gut. 2017 Jul;66(7):1241-1251.