Introduction

Confocal laser endomicroscopy (CLE) can detect acute duodenal epithelial disruption in response to food application, potentially identifying personalized elimination diets (1). A pilot study in functional dyspepsia (FD) showed that the 6-food elimination diet (6FED) provided symptom relief. (2). Earlier research in FD, however, showed that the high rate of acute food-induced mucosal alterations on CLE were not associated with altered permeability or changes in mast cell activation ex vivo (3).

Aims & Methods

To evaluate a personalized elimination diet in patients living with FD based on results of CLE, assessing duodenal mucosal changes to locally applied food solutions from the 6FED.
A randomized, double-blind, cross-over, sham-controlled trial was conducted in 17 Rome IV FD patients, in whom immunoglobulin E (IgE) sensitization to nutrients was excluded via food-specific serum IgEs. Baseline symptoms were assessed using the Leuven Postprandial Distress Scale (LPDS) and Patient Assessment of GI Disorders–Symptom Severity Index (PAGI-SYM). Index upper GI endoscopy (EGD) was followed at least 2 weeks later by an EGD with CLE. During CLE, duodenal mucosa was visualized at baseline and after consecutive, random administration of egg white, soy, milk, wheat, lyophilized fish/shellfish and nuts solutions. In case of a reaction to the first 2 food solutions, an additional CLE was scheduled. All patients underwent a crossover dietary intervention excluding foods to which they tested positively (real diet, RD) and negatively (sham diet, SD) in random order. Following 4 weeks of diet, LPDS and PAGI-SYM scores were reevaluated. Missing data were considered non-responder, based on an extreme case approach. Data are reported as mean ± SEM. Comparisons were done using a paired t-test or related-Samples Wilcoxon test, as applicable. Response rate was evaluated using a McNemar test. P<.05 is considered significant.

Results

Dietary outcome was available from 17 patients (age 35±3.7y, 16 female, BMI 22±0.7 kg/m2). In 7% of exams (n=2), acute alterations were already present at baseline. Twelve patients (71%) underwent a second CLE procedure. One patient dropped out after the first diet (which was RD). Three patients did not have a reliable RD/SD comparison due to non-response (n=1) or early response on CLE (n=2), underwent a standardized control diet, and were excluded from the analysis. Among the 14 patients in the cross-over dietary intervention, the proportion with a clinically significant 0.7 decrease in LPDS was similar for both diets (RD 4/14 vs. SD 2/14, p=0.41). No significant differences were found in LPDS subdomains or in the total PAGI-SYM score or PAGI-SYM fullness domain between the two diets (all p>.05).

Conclusion

In patients with FD, without systemic IgE-sensitization, CLE visualized a high rate of acute, food-induced, mucosal alterations, which could not be translated in symptom benefit following a dietary intervention excluding these foods vs. foods that did not trigger a reaction in this double-blind, controlled diet intervention study. None of the analyzed clinical outcome measures differed between the two diets. Given the results of this first double-blind controlled diet intervention in patients living with FD, CLE-based diets cannot be recommended in this population.

References

1. Fritscher-Ravens A, Schuppan D, Ellrichmann M, Schoch S, Rocken C, Brasch J, et al. Confocal endomicroscopy shows food-associated changes in the intestinal mucosa of patients with irritable bowel syndrome. Gastroenterology. 2014;147(5):1012-20 e4.
2. Schol J, Vanuytsel T, Routhiaux K, Huang I, Balsiger L, Van Den Houte K, et al. The six-food elimination diet improves symptoms of functional dyspepsia. Submitted for publication. 2025.
3. Van de Bruaene C, Schol J, Balsiger L, Raymenants K, Toth J, Farre R, et al., editors. Observation of local, food-induced changes of the duodenal mucosa in functional dyspepsia cannot be translated in permeability alterations or changes in mast cell activation ex vivo. F; 2024; Bangkok, Thailand: Neurogastroenterology And Motility.

Introduction

Advances in non-celiac wheat sensitivity (NCWS) have proved that it should be considered a protean condition in which several potential triggers [e.g. gluten, wheat amylase-trypsin inhibitors, etc.] might determine an intestinal mucosal damage with increased permeability and exposure of foods/microbial peptides to immune cells (1,2), resulting in both a local and systemic inflammatory activation responsible for its gastrointestinal and extraintestinal manifestations (3,4). Up to 75% of NCWS subjects complain of multiple foods hypersensitivities (MFH) (5). These patients usually have clinical, immunological and histological features similar to wheat allergy patients, although without positive gluten/wheat IgE assays, allowing to hypothesize the existence of a non-IgE mediated hypersensitivity. In addition, several studies have reported an association between atopic diseases and NCWS.

Aims & Methods

This study aimed to define the presence and features of atopic diseases and other hypersensitivities (primarily food allergies/intolerances) in NCWS compared with celiac disease (CD) and irritable bowel syndrome/functional dyspepsia (IBS/FD) and to analyze a possible correlation between these diseases and NCWS clinical manifestations. This retrospective, multicenter study included NCWS patients diagnosed by double-blind placebo-controlled challenge with wheat. Their clinical, laboratory and histology data at diagnosis (i.e. before the start of a wheat-free diet) were analyzed and compared to control subjects with CD and IBS/FD. Specific allergology data, other than clinical/laboratory features typical of NCWS, were collected and analyzed: family and personal history of atopic diseases, type of allergens responsible, positivity of skin prick tests (SPT), patch tests and total and food-specific IgE.

Results

Atopic disease prevalence was higher in NCWS (32.8%) than in CD (19.3%) and IBS/FD (21.5%) (P=.001 for both). Similarly, NCWS subjects had a higher frequency of MFH (39.8%) and self-reported milk intolerance (SRMI) (65.9%) compared to the controls (P <.001 for both). Allergic asthma, either alone (P=.03) or associated with allergic rhinitis (P=.005), was more prevalent in NCWS compared to IBS/FD, which was more often associated with allergic conjunctivitis (P=.004) or allergic rhinitis alone (P=.02). Graminaceae hypersensitivity and nickel allergic contact dermatitis (Ni-ACD) were more frequent in patients with NCWS (70.1% and 17.8%) vs both CD (48.7% and 9.4%, P=.03 and P=.01, respectively) and IBS/FD (50.8% and 6.7%, P=.01 and P<.001, respectively). On multiple logistic regression analysis, a coexistent atopic disease (OR 1.481), MFH (OR 3.882) and SRMI (OR 2.259) were associated with the NCWS diagnosis. NCWS subjects with atopy compared to those without more frequently had Ni-ACD (P<.001) and SRMI (P=.03), positive patch test (P<.001), SPT for foods (P=0.001) and both total and food-specific serum IgE (P=.02 and P=.002, respectively). On multiple logistic regression analysis, positivity to patch test (OR 2.955), SPT for foods (OR 5.799), and food-specific serum IgE (OR 3.101) were confirmed as differentiating the 2 subgroups.

Conclusion

NCWS subjects have a higher frequency of atopic disease, MFH and SRMI compared to both CD and IBS/FD ones. These conditions could be expression of an underlying hypersensitivity milieu characterizing NCWS and might be of support in the differential diagnosis between NCWS and functional gastrointestinal disorders, if inserted into a broader diagnostic panel.

References

1) Zevallos VF, Raker V, Tenzer S, Jimenez-Calvente C, Ashfaq-Khan M, Rüssel N, et al. Nutritional Wheat Amylase-Trypsin Inhibitors Promote Intestinal Inflammation via Activation of Myeloid Cells. Gastroenterology. 2017;152:1100-1113.e12.
2) Uhde M, Ajamian M, Caio G, De Giorgio R, Indart A, Green PH, et al. Intestinal cell damage and systemic immune activation in individuals reporting sensitivity to wheat in the absence of coeliac disease. Gut. 2016;65:1930–7.
3) Volta U, De Giorgio R, Caio G, Uhde M, Manfredini R, Alaedini A. Nonceliac Wheat Sensitivity. Gastroenterol Clin North Am. 2019;48:165–82.
4) Catassi C, Elli L, Bonaz B, Bouma G, Carroccio A, Castillejo G, et al. Diagnosis of Non-Celiac Gluten Sensitivity (NCGS): The Salerno Experts’ Criteria. Nutrients. 2015;7:4966–77.
5) Carroccio A, Mansueto P, Iacono G, Soresi M, D’Alcamo A, Cavataio F, et al. Non-Celiac Wheat Sensitivity Diagnosed by Double-Blind Placebo-Controlled Challenge: Exploring a New Clinical Entity. American Journal of Gastroenterology. 2012;107:1898–906.

Disclosure

This study is funded by the European Union - Next Generation EU, Mission 4, Component 1 CUP B53D23031860001, Project Code: P2022Z9RZY_001.

Introduction

The Atmo Capsule is a wireless motility capsule that senses and telemetrically transmits measurements of hydrogen (H₂) and carbon dioxide (CO₂) along the gut. In the colon, luminal concentrations of H₂ and CO₂ represent the metabolic activity of the microbial community. We hypothesized that delayed colonic transit would lead to altered gas profiles due to earlier depletion of fermentable substrates relative to transit time and/or facilitation of contact between methanogens and hydrogen (Levitt et al. CGH 2006).

Aims & Methods

The Atmo Capsule was administered to subjects with suspected upper and/or lower gut dysmotility. Colonic transit times (CTT) ≥ 59 h were considered delayed. Luminal H₂ and CO₂ concentrations (as time-normalized, area-under-the-curve [TN-AUC], [%.h]/h) were evaluated across the entire colon. Regional colonic profiles were evaluated per quartile of relative colonic transit, with quartiles 1 and 4 indicative of the proximal and distal colon, respectively. Gas measures were included if ≥ 50% of data were available for the corresponding segment. Fermentation profiles were estimated by the ratio of quartile 1:4 values, and time to peak concentrations were evaluated relative to CTT. Data were analyzed via Mann-Whitney test.

Results

The Atmo Capsule was administered to 209 subjects (median age 41; 188 female) with 170 yielding valid data on both colonic transit and colonic gas concentrations. Delayed colonic transit was identified in 60/170 (35%) subjects. In subjects with delayed CTT, H₂ concentrations tended to be higher in the proximal colon and lower in the distal colon with no overall difference across the region compared with those with normal transit (Table 1). CO₂ concentrations were higher throughout the colon except in the distal colon in subjects with delayed CTT. Peak concentrations of colonic H₂ and CO₂ were higher (H2, 8.7 h vs 5.9 %.h/h, p<0.01; CO2, 37.4 vs 29.9 %.h/h, p<0.01) and tended to occur earlier (H₂, 35.9 vs 47.0 % of colonic transit p=0.14; CO₂, 49.1 vs 86.8 % colonic transit, p<0.01) in patients with delayed compared with normal CTT.

Table 1. Gas profiles in patients with delayed colonic transit and correlation with symptom profiles. Data shown as median (interquartile range) and analyzed via Mann-Whitney test.

Conclusion

Colonic gas profiles, as measured via the Atmo Capsule, differed in patients with delayed compared with normal CTT, with patterns suggesting progressive depletion of fermentable substrates and/or conversion of H2 to methane during transit in those with delayed transit.

References

Levitt MD, Furne JK, Kuskowski M, Ruddy J. Stability of human methanogenic flora over 35 years and a review of insights obtained from breath methane measurements. Clin Gastroenterol Hepatol. 2006 Feb;4(2):123-9. doi: 10.1016/j.cgh.2005.11.006. PMID: 16469670.

Disclosure

These authors disclose the following: Braden Kuo, Anthony J. Lembo, Eammon M.M. Quigley, Satish S.C. Rao, and William D. Chey serve on the Medical Advisory Board of Atmo Biosciences. Michael Cline and Baharak Moshiree served on the Medical Advisory Board of Atmo Biosciences. Braden Kuo has received funding from NIH, Vanda, Atmo Biosciences, and Takeda and has consulted for Evoke, Takeda, Ironwood, Novo Nordisk, Cindome, and Neurogastrx. Thomas Abell has received funding from Gastric Dysrhythmias, Neurogastrx, NIH GpCRC, and Vanda and has consulted for Enterra Medical, Novo Nordisk, Nuvaira, and Vanda. Anthony J. Lembo has received funding from Ardelyx, Biomerica, GSK, Ironwood, Takeda, and Vibrant and holds stock with Allurion, Bristol Myer Squibb, and J&J. Abigail Stocker has received funding from Cindome, Enterra Medical, and Vanda. William D. Chey has received funding from Atmo Biosciences, Commonwealth Diagnostics Intl, QOL Medical, and Salix; has consulted for AbbVie, Ardelyx, Biomerica, Comvita, Gemelli, Ironwood, Nestle, QOL Medical, Phathom, Redhill, Salix, Vibrant, and Takeda; has filed patents with My Nutrition Health, Digital Manometry, and Rectal Expulsion Device; and holds stock options with Coprata, Evinature, Food Marble, Kiwi Bioscience, and Modify Health. The remaining authors disclose no conflicts.

Introduction

Gastric visceral hypersensitivity (VH) is a key pathophysiological feature of functional dyspepsia (FD), characterized by enhanced perception of gastric distension and postprandial pain. Recent studies suggest that dietary gluten may act as a pro-nociceptive factor in FD, particularly in individuals without celiac disease but with dyspeptic symptoms. However, mechanisms linking gluten to VH remain elusive.

Aims & Methods

In the clinical arm, multiple linear regression assessed associations between gluten intake and symptom frequency/severity (postprandial fullness, epigastric pain, early satiety), adjusting for age, sex, and BMI. In the experimental arm, Sprague-Dawley rats received either a 20% gluten diet or gluten-free diet for 8 weeks; an iodoacetamide-induced FD model served as a positive control. Gastric sensitivity was evaluated by abdominal withdrawal reflex (AWR) and electromyography (EMG) following surgical placement of a gastric balloon and electrodes. Duodenal and fecal samples were collected for 16S rRNA microbiota profiling and RNA-seq. Histological and molecular analyses included H&E staining, intraepithelial lymphocyte (IEL) counts, RT-qPCR of cytokines, and quantification of GFAP, Substance P, and MAPK components by RT-qPCR, Western blot, or immunofluorescence. Aprepitant (10 mg/kg/day) was administered during the final 2 weeks to assess its therapeutic effect.

Results

A total of 74 patients diagnosed with FD based on Rome IV criteria (EPS (epigastric pain syndrome)+PDS (postprandial distress syndrome): 29, EPS: 12, PDS: 33) and 29 healthy controls were included. FD patients, particularly EPS subtypes, exhibited significantly higher gluten intake than healthy controls (P＜0.001). Multiple linear regression revealed that gluten intake was a significant positive predictor of symptom frequency and severity in FD patients (frequency: β = 0.0407, 95% CI: 0.0197–0.0617, P ＜0.001; severity: β = 0.0230, 95% CI: 0.0091–0.0368, P＜0.01).
In rats, gastric sensitivity in the 20% gluten group was comparable to the iodoacetamide-induced FD model and significantly greater than the gluten-free control group, exhibited by slower weight gain, increased AWR score, higher area under the curve (AUC) of electromyograph and reduced 24-hour food intake. Compared to controls, gluten-fed rats showed reduced fecal abundance of Lactobacillus and Lactococcus, increased Lachnoclostridium, and decreased Lactococcus in duodenal mucosa. Duodenal tissues also exhibited elevated intraepithelial lymphocyte (IEL) counts, increased expression of IL-1β, IL-4, and IL-5, and upregulation of inflammation-related genes Reg1α and Reg3β, indicating low-grade mucosal inflammation. In addition, gluten exposure significantly increased duodenal expression of Substance P (SP), GFAP, and phosphorylated MAPK pathway proteins.
At week 8, rats in the gluten group were treated with either the NK1R antagonist aprepitant or saline. Aprepitant administration significantly attenuated VH, as shown by reduced AWR scores and EMG AUC compared with the gluten+saline group. Aprepitant also suppressed the expression of IL-1β, IL-4, Reg1α, Reg3β, and MAPK-related genes, suggesting a key role of SP-mediated neuroimmune activation in gluten-induced VH.

Conclusion

Long-term high gluten intake induces gastric hypersensitivity, accompanied by gut dysbiosis, mucosal inflammation, and SP-mediated MAPK signaling. Targeting neuroimmune pathways may offer novel therapeutic strategies for gluten-induced epigastric symptom management.

References

POMENTI S, DEVINSKY J, JODORKOVSKY D. Diet for Functional Gastrointestinal Disorders/Disorders of Gut-Brain Interaction [J]. The Medical clinics of North America, 2022, 106(5): 899-912.
SHAH A, KANG S, TALLEY N J, et al. The duodenal mucosa associated microbiome, visceral sensory function, immune activation and psychological comorbidities in functional gastrointestinal disorders with and without self-reported non-celiac wheat sensitivity [J]. Gut microbes, 2022, 14(1): 2132078.