Introduction

The pathophysiological mechanism involved in irritable bowel syndrome (IBS) is thought to be multifactorial, involving the gut-brain axis and the immune system. Despite this complexity, dietary restriction of fermentable oligo-, dis-, mono- saccharides, and polyols (FODMAPs) has become the first line of treatment, improving symptoms in up to 80% of patients (1). FODMAPs are poorly absorbed in the small intestine and serve as a substrate for the colonic microbiota, which has been proposed as a key mediator of FODMAP tolerance and symptom development. Considering that both the gut microbiota and the (in)tolerance to individual FODMAPs are highly personalised (2), there is a growing need to understand the host-microbiota interactions underlying individual responses to FODMAP restriction and intake. This personalised interplay may be key to more targeted dietary interventions for IBS.

Aims & Methods

We aimed to disentangle the role of the gut microbiota in FODMAP tolerance by exploring microbial dynamics upon restriction and reintroducing individual FODMAPs. To this end, we performed 16S rRNA gene sequencing of over 1,700 faecal samples from 463 IBS patients participating in two clinical trials: a) The DOMINO trial (3), where primary-care patients underwent a FODMAP-lowering diet and b) A cohort of 117 tertiary-care patients underwent a strict FODMAP-restriction followed by a blinded re-introduction of 6 FODMAPs powders (2). Response to the diet was defined as a reduction of at least 50 points on the IBS symptom severity scale. Linear and logistic mixed models were used to assess the relation between the microbiome, response to dietary intervention, host genetics and 32 blood and faecal parameters.

Results

Participants with dysbiotic microbiota at baseline were shown to be less likely to respond to the dietary restriction (p-value=0.01). These participants also showed higher levels of fecal calprotectin, secretory IgA and eosinophil-derived neurotoxin, suggesting immune activation in this subgroup of IBS patients (p-value<0.05). In both cohorts, limiting FODMAP intake was associated with decreased Bifidobacterium abundance (FDR<0.01). Moreover, a dose-dependent effect was observed as depletion was less severe in the FODMAP-lowering DOMINO diet. This effect was independent of response and IBS subtype. Furthermore, total bacterial biomass did not change during the restriction or the reintroduction period. However, we found 25 significant associations between individual FODMAPs and gut bacteria. The reintroduction of galacto-oligosaccharides and fructans restored the levels of Bifidobacterium, while polyols increased the abundance of Anaerostipes, regardless of participants’ tolerance (FDR<0.05). In addition, we observed distinct dynamics in the gut microbiota associated with the tolerance of specific FODMAPs, although they did not reach significance after multiple testing corrections at the current sample size. For example, participants intolerant to sorbitol showed an increase in Alistipes upon exposure to this compound (p-value<0.05, FDR>0.05).

Conclusion

Our results suggest that microbiota composition at baseline influences the clinical response to FODMAP restriction. A low-FODMAP diet does not induce drastic changes in the microbiome composition, although we confirmed the negative impact of dietary restriction on the abundance of Bifidobacterium. However, the less restrictive DOMINO diet results in a milder depletion, suggesting that moderate FODMAP reduction may better preserve beneficial microbiota while still offering symptom relief. Finally, we found evidence for a link between microbial dynamics and FODMAP tolerance, although this needs to be confirmed in larger cohorts.

References

(1) Staudacher HM, Whelan K The low FODMAP diet: recent advances in understanding its mechanisms and efficacy in IBS Gut 2017;66:1517-1527.
(2) Van den Houte K, Colomier E, Routhiaux K, Mariën Z, Schol J, Van den Bergh J, Vanderstappen J, Pauwels N, Joos A, Arts J, Caenepeel P, De Clerck F, Matthys C, Meulemans A, Jones M, Vanuytsel T, Carbone F, Tack J. Efficacy and Findings of a Blinded Randomized Reintroduction Phase for the Low FODMAP Diet in Irritable Bowel Syndrome. Gastroenterology. 2024
(3) Carbone F, Van den Houte K, Besard L DOMINO Study Collaborators, et al Diet or medication in primary care patients with IBS: the DOMINO study - a randomised trial supported by the Belgian Health Care Knowledge Centre (KCE Trials Programme) and the Rome Foundation Research Institute Gut 2022;71:2226-2232.

Disclosure

JT has given Scientific advice to AlfaWassermann, Allergan, Christian Hansen, Danone, Grünenthal, Ironwood, Janssen, Kiowa Kirin, Menarini, Mylan, Neutec, Novartis, Noventure, Nutricia, Shionogi, Shire, Takeda, Theravance, Tramedico, Truvion, Tsumura, Zealand and Zeria pharmaceuticals, has received research support from Shire, Sofar and Tsumura, and has served on the Speaker bureau for Abbott, Allergan, AstraZeneca, Janssen, Kyowa Kirin, Menarini, Mylan, Novartis, Shire, Takeda, Truvion and Zeria. Funding was provided by a Methusalem grant from Leuven University to JT This study was supported by a research grant from the Belgian Health Care Knowledge Centre (KCE).

Introduction

Pathological esophageal acid exposure may persist in patients with Barrett’s esophagus (BE) despite standard proton pump inhibitor (PPI) therapy and symptom control, although current guidelines recommend at least standard-dose PPI for all patients with BE.¹

Aims & Methods

Aim was to evaluate the role of esophageal function testing in assessing acid exposure in BE patients on PPI therapy and in predicting neoplastic progression. We conducted a multicenter retrospective study including asymptomatic BE patients (defined by GerdQ total score <8 and a score of 0 on the first GerdQ item) who underwent high-resolution manometry and 24-hour pH impedance monitoring while on various PPI regimens. Maximal PPI therapy included esomeprazole 40 mg, pantoprazole 40 mg, rabeprazole 20 mg, or lansoprazole 30 mg, all administered twice daily. All other regimens were considered standard dosing. Index upper endoscopy with biopsies was performed under the same therapeutic regimen. Histologically, presence and degree of neoplasia (all confirmed by a second pathologist) was recorded. Acid exposure time (AET) <4% was defined as adequate acid control; AET >6% as pathological reflux. Predictors of pathological reflux and neoplasia were assessed using logistic regression analysis.

Results

A total of 135 patients (2016-2025) were included (mean age 58 ± 15 years; 73% male). Median BE length was C1 (range 0–3 cm) and M2 (range 1–5 cm), with 41% (n=56) classified as having long-segment BE. Sixty-seven patients (50%) were on standard-dose PPI. Pathological reflux was identified in 37 patients (27%), of whom 25 (67%) were on standard-dose therapy. Fourteen patients (10%) had borderline AET values (4–6%). Among the 84 patients (62%) with adequate acid control, 33 (39%) were taking standard-dose PPI. On multivariable analysis, standard-dose PPI (OR 3.04; 95% CI 1.34–6.89; p=0.008) and type III esophagogastric junction morphology (OR 2.52; 95% CI 1.01–5.01; p=0.047), consistent with manometric hiatal hernia, were independently associated with pathological reflux. Non-dysplastic BE was found in 112 patients, while 13 (10%) had neoplasia at index endoscopy (8 low-grade dysplasia, 3 high-grade dysplasia, 2 intramucosal adenocarcinoma). Pathological reflux was the only independent predictor of neoplasia (OR 10.41; 95% CI 2.65–41.26; p<0.001).

Table 1. Logistic regression analysis for factors associated with neoplasia on index endoscopy.

Conclusion

Nearly one-third of asymptomatic BE patients exhibit pathological reflux on pH-monitoring despite PPI treatment, predominantly among those on standard-dose and with manometric hiatal hernia. Nonetheless, adequate acid control is achieved in over one-third of patients on standard PPI therapy. Pathological reflux is associated with a 10-fold increased risk of neoplasia.

References

1. Shaheen NJ, Falk GW, Iyer PG, et al. Diagnosis and Management of Barrett's Esophagus: An Updated ACG Guideline. Am J Gastroenterol. 2022;117(4):559-587.

Introduction

Non-celiac gluten/wheat sensitivity (NCGWS) is characterized by gastrointestinal and extra-intestinal symptoms triggered by gluten/wheat ingestion. Symptoms of NCGWS overlap with those of irritable bowel syndrome (IBS) or functional dyspepsia (FD). Due to diagnostic challenges and symptom overlap, data on the prevalence and predictors of NCGWS among patients with IBS or FD, especially those with refractory symptoms, are limited.

Aims & Methods

This was a prospective, multicentric, double-blind, placebo-controlled, crossover trial conducted from October 2021 to March 2023 in India.This was prospectivly registered with the clinical trials Registry, INDIA (CTRI/2021/10/037323). Adults aged 18–65 years with Rome IV-defined irritable bowel syndrome (IBS) or functional dyspepsia (FD) refractory to standard treatment were enrolled after excluding celiac disease, wheat allergy, and alarm features. Participants underwent a two-step diagnostic protocol. In Step I, patients adhered to a 6-week strict gluten-free diet (GFD) under dietitian supervision. Weekly assessments of gastrointestinal and extra-intestinal symptoms, health-related quality of life (HRQoL), and psychological scores were performed using validated instruments. Gluten responders—defined by ≥30% reduction in one to three primary symptoms—were advanced to Step II: a randomized, double-blind, placebo-controlled gluten challenge with crossover. Subjects received indistinguishable gluten or placebo cookies (8 g/day) for one week, followed by a one-week washout and crossover. A ≥30% symptom difference between gluten and placebo phases confirmed non-celiac gluten/wheat sensitivity (NCGWS). Primary outcome was NCGWS prevalence; secondary outcomes included symptom and HRQoL changes post-GFD and predictors of NCGWS. Statistical analyses included intention-to-treat principles and multivariable regression to identify baseline predictors.

Results

Of the 252 patients screened, 177 were enrolled for 6-week GFD (step I), and 154 patients completed this phase (mean age 41.9±14.2 years, 53.2% males). Eighty two (52.3%) patients responded to GFD, of whom 77 entered step 2 (DBPCGC). Thirty one (20.1%) patients had significant symptom worsening on blinded gluten ingestion, suggesting the presence of NCGWS. Independent predictors of NCGWS were female gender, FD-IBS overlap, headache, fatigue, and anxiety. Significant improvements in gastrointestinal symptoms, health-related quality of life, and psychological scores were observed after GFD in responders. No significant impact of diet sequence was noted.

Conclusion

Introduction

Eosinophilic esophagitis (EoE) is a chronic, progressive, esophageal disease driven by type 2 inflammation.

Aims & Methods

The aim of this analysis was to determine the histopathologic effect of dupilumab on esophageal inflammation in patients aged 1–11 years with eosinophilic esophagitis (EoE) from the phase 3 EoE KIDS trial. In Part A, patients were randomized to receive weight-tiered dupilumab or placebo for 16 weeks. In Part B, all patients received weight-tiered dupilumab for 36 weeks. Biopsies from proximal, mid, and distal esophageal regions were analyzed. Peak eosinophil count (PEC) and EoE Histologic Scoring System (HSS) grade/stage scores were assessed at baseline, Week 16, and Week 52.

Results

At Week 16, dupilumab vs placebo treatment resulted in significantly greater improvements in PEC (least squares mean percent change -86.09% vs 20.98%, respectively; P<0.0001) and improvements from baseline were observed in EoE-HSS grade and stage total scores, and inflammatory and architectural sub-scores (Table). Improvements were maintained at Week 52 with continued dupilumab. For those who switched from placebo at Week 16, improvements were observed at Week 52. Improvements in individual component scores were also observed.

Table. Mean percent change from Part A baseline in EoE-HSS scores at Weeks 16 and 52.

Conclusion

Dupilumab treatment improved a range of histopathologic aspects of EoE through 52 weeks versus placebo in children aged 1–11 years with EoE.

Disclosure

Collins MH: Arena, Pfizer, AstraZeneca, Calypso Biotech, EsoCap Biotech, GSK, Receptos, Celgene, Bristol Myers Squibb, Regeneron Pharmaceuticals Inc., Robarts Clinical Trials Inc. Alimentiv, Inc., Sanofi, Shire, a Takeda company – advisory board/consultancy fees.
Lerner D: Regeneron Pharmaceuticals Inc. – educational board fees.
Pesek RD: Regeneron Pharmaceuticals Inc. – advisory board/consultancy fees.
Zevit N: AstraZeneca, Rafa Inc., Regeneron Pharmaceuticals Inc., Sanofi, Takeda – advisory board/consultancy fees. Adare Pharmaceuticals, Dr. Falk Pharma – advisory board/consultancy fees. Dr. Falk Pharma, Rafa Inc., Regeneron Pharmaceuticals Inc., Sanofi – speaker fees. Rome Foundation – honoraria.
Xia C, Raphael BP, Radwan A: Regeneron Pharmaceuticals Inc. – employees and shareholders.
Zaghloul S, Angello JT: Sanofi – employees, may hold stock and/or stock options in the company.