Introduction

Dietary intervention is well recognised as an effective treatment for Crohn’s disease in children, and there is a growing evidence base for its use in adults in inducing and maintaining remission¹. It has a number of advantages over standard therapy including a low side effect profile and being cost effective, but despite this nutrition therapy is underused in practice².

Aims & Methods

To investigate the efficacy of the addition of dietary intervention including elemental formula and a Low Fat/ Fibre Limited Exclusion (LOFFLEX) diet in addition to standard therapy on outcomes in Crohn’s disease, compared to standard therapy alone.
A cohort of patients at MDHB in Palmerston North, New Zealand, with Crohn’s disease who were started on dietary intervention as monotherapy or in addition to standard therapy in non-responsive patients between the beginning of 2019 and the end of 2021 were analysed retrospectively. A cohort of patients treated with standard therapy alone, which includes treatment with 5ASA, immunomodulator and biologic therapy were also retrospectively recruited from a database of IBD patients at MDHB. Baseline data for both groups were collected and standardised using regression model analysis for baseline characteristics including duration of disease, gender, smoking status, location and behaviour of disease, baseline Harvey-Bradshaw Index (HBI) and C-reactive protein (CRP).
Outcomes for both groups were measured using number of flares (defined by course of steroids and/or hospital presentations), biochemical markers including CRP and faecal calprotectin, and a composite marker of symptoms using the Harvey Bradshaw Index.
We fitted a mixed effects model to the response (i.e. HBI, CRP, faecal calprotectin and number of flares) separately with a fixed effects of time (12 and 24 months) for the nutrition and standard groups.

Results

At the 12 month mark, patients on nutrition therapy had a significantly lower HBI (1.9126) compared to those on standard therapy alone (4.3454 with a p-value of 0.0026. There was no significant difference between groups at 24 months. There was no statistically significant difference between the groups for other outcome measures including CRP, faecal calprotectin, and number of flares.

Conclusion

Our study suggests nutrition therapy in Crohn’s disease is effective as monotherapy or when combined with other treatment modalities in non-responsive patients already on pharmacotherapy. At the 12-month duration nutrition therapy was more effective in this group compared to patients on standard therapy based on the Harvey-Bradshaw Index, suggesting a potential alternative treatment approach for adults with mild to moderate Crohn’s disease, and highlighting the need for further research in this area.

References

• Zulkiflee, Nuur Hj, et al. "PTH-28 Elemental formula and LOFFLEX nutrition therapy; an effective but neglected treatment strategy in Crohn’s disease." (2021): A184-A185.
• Woolner, J., et al. "The development and evaluation of a diet for maintaining remission in Crohn's disease." Journal of Human Nutrition and Dietetics 11.1 (1998): 1-11.
• Luo, D., Ganesh, S., & Koolaard, J. (2021). Predictmeans: calculate predicted means for linear models [R package version 1.0.6]. https://CRAN.R-project.org/package=predictmeans.
• Douglas Bates, Martin Maechler, Ben Bolker, Steve Walker (2015). Fitting Linear Mixed-Effects Models Using lme4. Journal of Statistical Software, 67(1), 1-48. doi:10.18637/jss.v067.i01.

Introduction

The pathophysiology of disorders of gut-brain interaction is complex and incompletely understood. In functional dyspepsia, increased gut permeability and low-grade mucosal inflammation with eosinophils and mast cells have been reported. Stress as well as exogenously administered corticotropin-releasing hormone (CRH) have been shown to increase small bowel permeability in vivo in a mast-cell dependent fashion. Moreover, eosinophil-derived CRH has been implicated in mast cell activation.

Aims & Methods

The aim of the current study was to evaluate whether acute CRH administration can induce increased duodenal mucosal permeability and immune activation in healthy volunteers (HVs).
HVs without gastrointestinal symptoms were recruited. The use of drugs such as NSAIDs, mast cell stabilizers or corticoids was prohibited. An i.v. bolus of 100 µg CRH or placebo (NaCl 0.9%) was administered in a crossover, double blind, randomized fashion with a 1-week washout period. Two hours after injection a gastroscopy with duodenal biopsies was performed. Duodenal permeability was evaluated in Ussing chambers measuring trans-epithelial electrical resistance (TEER) and the flux of a fluorescence-labeled dextran of 4kDa (FITC-D4). Duodenal biopsies were incubated at 37°C in culture medium for 24h. Sandwich ELISA was performed on supernatant for eosinophil derived neurotoxin (EDN), tryptase and chymase, corrected for biopsy weight. Analysis was performed using marginal mixed models in SAS. Correlation analysis was performed using Pearson correlation coefficient. Results are described as mean ± SEM. P-values < 0.05 were considered significant after correction for multiple testing.

Results

Twenty HVs (65% women, 27±1 years, BMI 23.2 ± 0.6 kg/m²) completed the study. Tryptase release in supernatant was significantly lower after CRH exposure, 6.06±0.88 ng/mL vs 4.03±0.46 ng/mL after CRH exposure (n=16, p= 0.031). Chymase release however, was not significantly different between both conditions (2805.82 ± 447.85 pg/mL/mg for placebo vs 2001.19±365.91 for CRH pg/mL/mg; p=0.27, n=15). There was a trend towards a decrease in EDN, after CRH exposure (13.3±2.05 µg/L/mg for placebo vs 8.96±1.11 µg/L/mg for CRH; p=0.061; n=16). Correlation analysis of delta values showed a significant correlation between ∆ tryptase and ∆ chymase (r 0.79, p=0.0062, n=10) and ∆ tryptase and ∆ EDN (r 0.60, p=0.019, n=15). No significant correlation was found between ∆ chymase and ∆ EDN (r 0.36, p=0.30, n=10).
A trend towards an decreased mucosal permeability was observed after CRH administration for TEER (25.75 ± 0.91 Ω.cm² for placebo vs 27.20 ± 1.44 Ω.cm² for CRH; p=0.056). Likewise, FITC-D4 flux was significantly lower in the CRH condition (41.4 ± 5.6 pmol for placebo vs 33.0 ± 2.7 pmol for CRH, p<0.0001). There was no significant correlation of delta values of FITC-D4 flux or TEER with delta values of supernatant for tryptase, chymase or EDN secretion.

Conclusion

Acutely administered CRH in vivo decreased tryptase release in supernatant of duodenal biopsies, suggesting an increased tryptase release in vivo, and decreased duodenal permeability in healthy subjects. However, no correlation between permeability and tryptase release was found.

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.

Introduction

Previous studies indicate that patients with irritable bowel syndrome (IBS) may present with altered fecal microbiota and metabolite profiles. While changes in bowel habits seem to not influence the microbiota dynamics, the stability of fecal metabolites in IBS patients has not been addressed yet.

Aims & Methods

This study aimed to assess the stability of the fecal metabolite profile over time, and its link with fluctuations of stool consistency. It used fecal samples from two cohorts (A and B) comprising healthy subjects and patients with IBS diagnosed according to either Rome III (Cohort A) or Rome IV (Cohort B) and subtyped using the Bristol Stool Form (BSF) scale. Cohort A collected fecal samples for 5 consecutive days that were analyzed by gas chromatography-tandem mass spectrometry (GC-MS/MS). Additionally, IBS patients collected up to 3 additional samples within one of those days. Cohort B collected fecal samples at week 0 (healthy and IBS) and week 4 (only IBS), later analyzed by liquid chromatography-MS (LC-MS). All participants reported stool consistency using BSF scale. Metabolome variation based on the metabolite intensity signals was assessed by Bray-Curtis dissimilarity in R (version 4.2.1). Additional statistical analyses were conducted in GraphPad (version 9.4.1).

Results

Cohort A (7 healthy subjects and 8 IBS patients with mixed bowel habits, IBS-M) provided 66 fecal samples. Twenty-nine samples were collected from Cohort B (7 healthy subjects, 3 IBS-M, and 8 IBS patients with predominant diarrhea). The metabolome of Cohort A (n=155 spectral features) at day 1 showed similar composition with a tendency towards a higher Bray-Curtis dissimilarity in the IBS group (0.026 (0.023-0.028) vs 0.028(0.025-0.032); p=0.10). Over a period of 5 days, metabolome dissimilarities were higher between- than within- individuals (Table 1) and fluctuated minimally over time for both healthy subjects and IBS patients. The stool type however changed more over time in the IBS than the healthy group (p<0.001). Consecutive samples taken within the same day showed higher compositional variance between- than within- IBS patients (Table 1). At individual level, the metabolomic profiles remained stable despite changes in the BSF score. In Cohort B, the metabolome profile comprised 6 999 spectral features. The metabolome dissimilarity was higher in IBS patients as compared to healthy subjects at week 0 (0.045(0.040-0.048) vs 0.048(0.042-0.054); p<0.05). In the IBS group, the metabolome was stable between week 0 and week 4 regardless of stool form and differed more between- than within-patients (Table 1).

Conclusion

The metabolite profile of fecal samples remains stable over time within an individual IBS patient independently of the variation in stool consistency. This study suggests the use of fecal metabolites as a potential non-invasive diagnostic tool in IBS.