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

Few studies have examined esophageal motility disorders in patients with type 2 diabetes operated with sleeve gastrectomy (SG) or gastric bypass (RYGB).

Aims & Methods

We have recently reported overall prevalence of gastroesophageal reflux disease (GERD) in this group of patients (1) and now aimed to investigate potential differences between the two surgical methods regarding the prevalence of dysmotility 5 years after surgery. Furthermore, we also aimed to analyse and report on the available GERD-data in detail.
In the Oseberg study (January 2013 – December 2022), 125 patients with BMI ≥ 35 kg/m² and type 2 diabetes were screened, sixteen patients were excluded or withdrew consent, leaving 109 patients allocated to SG (n=55) or RYGB (n=54). To assess reflux symptoms, GerdQ (Gastroesophageal reflux disease questionnaire) was completed. Gastroscopy and 24-hour pH monitoring were used to examine GERD. High-resolution manometry with the Chicago classification v3.0 was used to assess esophageal motility.

Results

At inclusion the average age was 47.7 years (SD 9.6), BMI was 42.3 kg/m2 (5.3), and 66% were women. At the 5-year follow-up, 29 (53%) patients in SG-group and 32 (59%) in RYGB-group underwent gastroscopy, 22 (40%) vs. 25 (46%) underwent 24-hour pH monitoring, 23 (42%) vs. 26 (48%) underwent manometry, and 42 (76%) vs. 42 (78%) completed GerdQ. The proportion of patients with GERD symptoms (GerdQ ≥8) was low in both groups, with a slightly lower prevalence after RYGB (2%) than after SG (14%). There was no difference in the prevalence of erosive esophagitis between the groups (38% in SG and 41% in RYGB), all findings with less advanced esophagitis (Los Angeles grades A and B), but one patient in each group had new onset Barrett's esophagus. The proportion of patients with pH<4 for more than 6% of the recording (Acid exposure time, AET) was significantly higher after SG compared with RYGB (59% versus 8%, p < 0.0001). Esophageal dysmotility was diagnosed in 14 (61%) after SG compared with 19 (73%) patients after RYGB. Most of these patients (n=22) had hypertensive or hypotensive lower esophageal sphincter (LES), with no difference between groups. The remaining 11 patients had ineffective esophageal motility (IEM) or elevated distal contractile integral (DCI). None of the patients with dysmotility reported swallowing difficulties or chest pain with food intake.

Conclusion

The Oseberg study demonstrates a high prevalence of asymptomatic esophageal dysmotility after SG or RYGB with uncertain clinical relevance. Furthermore, a seven times higher prevalence of pathological acid reflux after SG compared with RYGB was demonstrated, but the prevalences of erosive esophagitis and esophageal dysmotility were approximately similar between groups. Few of the examined patients reported GERD symptoms, hence objective assessment of GERD should be included in long-term follow-up after SG to detect and prevent the development of Barrett's esophagus, dysplasia, and adenocarcinoma.

References

1. Hauge JW et al., Effect of gastric bypass versus sleeve gastrectomy on the remission of type 2 diabetes, weight loss, and cardiovascular risk factors at 5 years (Oseberg): secondary outcomes of a single-centre, triple-blind, randomised controlled trial. Lancet Diabetes Endocrinol. 2025 Apr 1:S2213-8587(24)00396-6