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.

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

Gut microbiota in Crohn's disease (CD) exhibits considerable variability, with conflicting associations with disease severity and response to therapeutic intervention. We aimed to longitudinally investigate the dynamics of microbial composition in a cohort of patients with newly diagnosed, treatment-naïve Crohn's disease (ndCD) over a one-year period.

Aims & Methods

A prospective real-world study was conducted, enrolling patients with ndCD who were treatment-naïve. Treatment decisions were made by physicians with expertise in CD management. Key one-year clinical outcomes included corticosteroid-free clinical remission (CSFR) and biochemical remission (BR), defined as C-reactive protein levels <1mg/dL and fecal calprotectin levels <150ug/g. Paired stool samples were subjected to 16S rRNA gene sequencing (V4 region) at diagnosis and after one year, followed by analysis for microbial diversity and dysbiosis indices. A linear mixed-effect model was constructed to identify factors associated with microbial alterations and specific taxa driving these alterations, while controlling for confounding variables.

Results

Seventy-five patients completed the one-year follow-up (49.3% female, median age 27 years [IQR 22-38.5]); 45 (60%) received biologics (95.5% anti-tumor necrosis factor [TNF]). Rates of CSFR, BR, and combined CSFR-BR at one-year post-diagnosis were 64%, 56%, and 45.3%, respectively. Analysis of microbial composition revealed significant improvements in microbial indices among patients achieving all desired clinical outcomes, characterized by increased microbial diversity (Shannon index, p=0.004, p=0.002, p=0.004, respectively) and decreased dysbiosis (microbial dysbiosis index [MDI], p=0.003, p=0.04, p=0.01, respectively). Such improvements were not observed in patients failing to achieve CSFR, BR or combined CSFR-BR. Notably, patients treated with biologics, irrespective of outcome achievement, exhibited prominent shifts (improvement) in microbial composition (both indices p<0.001), whereas non-treated patients did not demonstrate significant changes (Shannon index, p=0.53; MDI, p=0.81). Furthermore, microbial composition at baseline was more disrupted among patients treated with biologics compared to non-treated patients (Shannon index, p=0.04; MDI, p=0.03). The linear mixed model analysis confirmed a positive association between biologics and favorable changes in microbial indices (Shannon index, p=0.02; MDI, p=0.04), identifying an increase in 20 gut commensal taxa (considered beneficial) and a decrease in Escherichia coli among the biologics-treated subgroup. Conversely, no taxa exhibited significant alterations in the non-biologics treated subgroup.

Conclusion

In a real-world cohort of patients with treatment-naïve ndCD, clinical improvement over one year was associated with improvement in microbial composition. Treatment with anti-TNF agents was associated with improvement in microbial composition irrespective of clinical outcomes. These findings suggest that microbial composition reflects inflammatory activity and may be positively and independently modified by anti-TNF treatment.