Introduction

Disorders of gut-brain interaction (DGBIs), such as functional dyspepsia and irritable bowel syndrome, are chronic gastrointestinal disorders with recurrent and bothersome abdominal symptoms. Although incompletely understood, immune activation, particularly involving eosinophils and mast cells, and visceral hypersensitivity have been implicated in their pathophysiology.

Aims & Methods

Using the normoglycemic Biobreeding diabetes-prone (BBDP-N) rat, we aim to 1) characterise the immune activation in jejunal and colonic mucosa and to 2) study the effect of budesonide, a local anti-inflammatory corticosteroid, on gut physiology and sensitivity.
90-day-old BBDP-N and Biobreeding diabetes-resistant (control) rats underwent a 28-day treatment with budesonide (0.5 mg/kg/day) or vehicle. Eosinophils and mast cells were identified by staining jejunal and colonic sections with Chromotrope 2R and anti-mast cell protease 2 antibody, respectively. To assess their activity, eosinophil peroxidase (EPO) and β-hexosaminidase levels were measured. Jejunal and colonic segments were mounted in modified Ussing chambers, and permeability was assessed by the transmucosal passage of a fluorescently labelled 20 and 4kDa dextran molecule (FITC-Dx4/20), and the transepithelial electrical resistance (TEER). Sensitivity to isobaric colorectal distension was assessed(1): the ∆ area under the curve (AUC) of the visceromotor response (VMR) to wall tension was calculated at baseline and after treatment. Depending on the normality of the data, an unpaired t-test or Mann-Whitney test was performed.

Results

Comparing vehicle-treated groups, the BBDP-N rats had higher numbers of jejunal eosinophils (1366.0±201.3 vs. 561.7±55.3 eosinophils/mm²; p<0.01) and mast cells (1151.0±136.7 vs. 549.1±44.8 mast cells/mm²; p<0.001), whereas only colonic eosinophil numbers were higher (222.7±40.4 vs. 128.9±14.5 eosinophils/mm²; p=0.03). Additionally, EPO levels were higher in the BBDP-N rats in both regions (jejunum: 59.4±9.8 vs. 4.4±3.0 µg/g tissue; p<0.01 & colon: 82.0±23.6 vs. 1.6±1.1 µg/g tissue; p<0.01), with no difference in mast cell activation. Following budesonide treatment, eosinophil (jejunum, BBDP-N: 167.3±53.6 vs. 1366.0±201.3 eosinophils/mm²; p<0.001 & control: 220.1±43.7 vs. 561.7±55.3 eosinophils/mm²; p<0.01, colon: BBDP-N: 58.2±11.9 vs. 222.7±40.4 eosinophils/mm²; p<0.01 & control: 78.1±14.4 vs. 128.9±14.5 eosinophils/mm²; p=0.01) and mast cell (jejunum: BBDP-N: 418.8±51.0 vs. 1151.0±136.7 mast cells/mm²; p<0.001 & control: 305.4±67.6 vs. 549.1±44.8 mast cells/mm²; p=0.01, colon: BBDP-N: 146.5±19.1 vs. 262.6±37.5 mast cells/mm²; p<0.01 & control: 137.4±17.8 vs. 244.9±29.4 mast cells/mm²; p<0.01) levels decreased in both groups in both regions. Colonic eosinophil activation was also reduced in BBDP-N rats (21.5±9.7 vs. 82.0±23.6 µg/g tissue; p=0.05), with no effect on mast cell activation. Jejunal permeability, assessed by 20kDa passage was increased in vehicle-treated BBDP-N rats (258.0±51.5 vs. 132.0±25.1 pmol/cm²; p=0.03). Budesonide treatment significantly increased colonic TEER in BBDP-N rats (73.2±4.3 vs. 38.3±4.1 Ω.cm²; p<0.001). Colonic sensitivity to distention was significantly reduced in BBDP-N following the treatment (-20.1±17.2 vs. 207.0±85.5 mV/s x mmHg.cm; p=0.02).

Conclusion

In conclusion, our work shows the importance of eosinophil and mast cell predominant immune activation in visceral hypersensitivity in a well-characterised preclinical model of DGBI. Anti-inflammatory treatments should be re-evaluated in DGBI with intestinal eosinophil and mast cell infiltration.

References

1: Meleine M et al. Neurogastroenterology and motility, 2019.

Introduction

Real-time symptom assessment provides a detailed understanding of the dynamic interplay between gastrointestinal symptoms in irritable bowel syndrome (IBS) and potential triggers, including affect and environmental factors. This study evaluates the association between abdominal pain and potential triggers over time in IBS patients with and without comorbidities, using the Experience Sampling Method (ESM) as a real-time, ecologically valid measurement method.

Aims & Methods

In this prospective, observational multicenter study, as part of the DISCOvERIE project, we included 215 Rome IV IBS patients (80% female; mean age 42.1) from six European countries, categorized into 103 IBS-alone, 67 IBS-mental (anxiety/depression), 16 IBS-somatic (fibromyalgia/chronic fatigue syndrome), and 29 IBS-multicomorbid patient subgroups. Participants scored abdominal pain and affect using an 11-point Numeric Rating Scale and environmental factors using ESM at up to ten random moments each day over seven consecutive days. Linear mixed-effects models analyzed the associations between abdominal pain and these potential triggers, both concurrently and predictively (trigger scores lagged by one time point, maximum of 90 minutes), in each subgroup.

Results

ESM assessment completion rate was 63%. Regarding affect triggers, abdominal pain was significantly correlated with concurrent positive and negative affect in all IBS groups (p<0.02), while significant lagged associations were only found within IBS-mental for positive affect (p=0.02) and within IBS-alone and IBS-multicomorbid for negative affect (p<0.001). Regarding environmental triggers, abdominal pain was significantly associated with concurrent ‘feeling comfortable in situation’ within IBS-alone, IBS-mental and IBS-multicomorbid (p<0.001), concurrent ‘feeling of pleasantness of company’ (p=0.01) and being alone (versus with somebody, p=0.01) within IBS-alone, and eating since the last ESM-assessment within IBS-alone (p=0.04) and IBS-multicomorbid (p=0.002). No significant lagged associations or correlations with location, activity, alcohol consumption, and nicotine use were found.

Conclusion

Our results demonstrate that in IBS patients, real-time abdominal pain is significantly associated with environmental and affect triggers, with both positive and negative affect correlating with abdominal pain irrespective of mental comorbidities. Moreover, fewer triggers predict abdominal pain over time, underscoring the importance of in-the-moment assessments. This study highlights the value of ESM in accurately identifying symptom triggers, thereby enhancing personalized healthcare in IBS.

Disclosure

MB, LV, MH, IM, SM, MRB, and DD declare no conflicts of interests. DJ has received research funding from public-private partnership grants of Top Knowledge Institute (TKI) Agri&Food and Health Holland, by the Carbokinetics program as part of the NWO-CCC Partnership Program, and by Organic A2BV/Mothersfinest BV. DK has received research funding from ZonMw, MLDS, UEG, Rome Foundation, Horizon Europe, Horizon 2020, Grunenthal, Allergan and speaker’s fee from Dr Falk (paid to host institute).

Introduction

Spasmolytic polypeptide expressing metaplasia (SPEM) is a cell repair lineage and is a very important phenotype of gastric mucosal injury and precancerous lesion.
Previously, parietal cells loss is considered as the first step and followed with chief cells transdiffernation to induce SPEM. But whether chief cells initial loss cause SPEM
needs to be further investigation. Acidic mammalian chitinase (CHIA) belongs to the 18 glycosidase family and is highly expressed in the chief cells. Our previous study showed that CHIA deficiency in the chief cells is the key event to induce SPME to progress to gastric cancer (Liu et al., DDW 2023 and 2024). However, the molecular role of CHIA in the development of SPEM is need further investigated.

Aims & Methods

Electron microscopy, qRT-PCR and single-cell sequencing (scRNA-seq) technology, as well as histopathological and immunofluorescence (IF) stainning with specific markers were performed in chief cells specific CHIA knockout mouse model (CHIA^rox/rox-GIF-Dre) and wild-type mice(CHIA^rox/rox), and in CHIA over - expression mice (CHIA ^rox/rox - GIF - Dre + rAAv - CHIA) and the control group (CHIA ^rox/rox - GIF - Dre + rAAv - control).

Results

Compared with CHIA^rox/rox mice, histological analysis and scRNA-seq technology data showed that loss of chief cells with increased M2 macrophage infiltration and final SPEM formation, but remaining of parietal cells in CHIA^rox/rox-GIF-Dre mice. Electron microscopy showed CHIA deficiency in mice resulted in endoplasmic reticulum was dilated and swollen, as well as the mitochondrial membrane was discontinuous of chief cells, followed with the accumulation of endoplasmic reticulum stress marker, including PERK, XBP-1, eIF2α/P-eIF2α, and GRP78, together with upregulation of pyroptosis-related marker, including NLRP3, ACS, GSDMD, NEK7, Caspase1, Caspase11, IL-1β, and IL-18, which was detected by qRT-PCR. These data indicating that target CHIA deletion caused chief cells pyroptosis. Furthermore, qRT-PCR analysis showed that CHIA deficiency caused the activation of IL33/IL-13 circuit in the mucosa of mice. Moreover, double immunofluorescence staining confirmed that upregulation and colocalization of IL-33 induced M2 macrophage polarization markers, including F4/80 and CD163⁺ with NLRP3 in the base of gastric mucosal of CHIA^rox/rox-GIF-Dre mice when compared with CHIA^rox/rox mice.Notably, CHIA ^rox/rox - GIF - Dre + rAvv - CHIA mice reversed the above process compared with controls.

Conclusion

Chief cells specific CHIA deficiency resulted in endoplasmic reticulum stress mediate NLRP3 inflammasome activation to induce chief cells proptosis.
Chief cells initial loss is sufficient and the key step to activate IL-33/ST2-M2 macrophage polarization axis to induce SPEM, which is independent of parietal cells loss.