Introduction

Somatic mutations in the APC gene represent an early event occurring in 80% of sporadic colorectal cancers (CRC), while germline mutations are responsible for the CRC-predisposing syndrome Familial Adenomatous Polyposis (FAP) [1]. APC-driven CRC are associated with deregulated Wnt/β-catenin pathway [2]. Intestinal patient-derived organoids are a useful tool to study intestinal physiology and related diseases because they can recapitulate the morphology, the heterogeneity, and the molecular profile of the original tissue [3]. Intestinal organoids long-term culture requires specific culture media, and different compositions have been studied and described, mainly focusing on their influence on organoids drug-response or staminality maintenance [4]. However, it remains unclear how specific culture media influence Wnt/β-catenin components in the study of molecular mechanisms involved in CRC development and progression.

Aims & Methods

The aim of the study was to evaluate the impact of different culture media formulations on Wnt/β-catenin pathway in organoids from sporadic CRC and FAP patients.
Intestinal organoids were obtained from normal-appearing mucosa (NM) tissues of three sporadic CRC and two FAP patients. Organoids were cultured with different growth media: Wnt3a-lacking/containing commercial medium (A+DMEM/A+B), or Wnt3a-conditionate medium lacking/containing homemade medium (Basal1X/Wnt3a-CM) with or without R-spondin1 (+/-RSpo1). The activation status of Wnt/β-catenin pathway was evaluated after 48 hours through RT-qPCR and Western blot on target genes (AXIN2, CCND1, C-MYC) and proteins (active and total-β-catenin); stemness and differentiation were evaluated through LGR5 and KRT20 gene expression. Organoids viability and morphology were analyzed with 3D cell viability assay and imaging software, respectively.

Results

As expected, analysis performed on CRC NM organoids indicated that complete media containing Wnt3a (A+B and Wnt3a-CM+/-Rspo1) increased AXIN2 gene expression compared to Wnt3a-lacking media. Interestingly, Wnt3a-CM+/-RSpo1, but not A+B, significantly increased also CCND1 and c-MYC expression. As a result, Wnt3a-containing media significantly enhanced intestinal staminality, and RSpo1 increased LGR5 expression by regulating the RSpo1/LGR axis. Also, in FAP NM organoids, A+B was less effective in increasing CCND1 and c-MYC expression, but the induction of AXIN2 and LGR5 expression was less potent than that obtained in CRC NM organoids. Western blot analysis confirmed the higher activation of WNT signaling in Wnt3a-CM+/-RSpo1 media compared to A+B, although the different culture media composition didn’t affect organoid viability and morphology.

Conclusion

The use of commercial or homemade Wnt3a-containing media and distinctive intrinsic status of Wnt/β-catenin activation of different tissues (e.g FAP NM) influence the regulation of Wnt/β-catenin pathway. These results underline the importance of choosing the right organoids media composition for studying molecular mechanisms underlying colorectal carcinogenesis.

References

[1] Fodde R, Smits R, Clevers H. APC, signal transduction and genetic instability in colorectal cancer. Nat Rev Cancer. 2001;1(1):55-67. doi:10.1038/35094067
[2] Yu, F., Yu, C., Li, F. et al. Wnt/β-catenin signaling in cancers and targeted therapies. Sig Transduct Target Ther 6, 307 (2021). https://doi.org/10.1038/s41392-021-00701-5
[3] Wang Q, Guo F, Jin Y, Ma Y. Applications of human organoids in the personalized treatment for digestive diseases. Signal Transduct Target Ther. 2022;7(1):336. Published 2022 Sep 27. doi:10.1038/s41392-022-01194-6
[4] Wilson SS, Mayo M, Melim T, et al. Optimized Culture Conditions for Improved Growth and Functional Differentiation of Mouse and Human Colon Organoids. Front Immunol. 2021;11:547102. Published 2021 Feb 12. doi:10.3389/fimmu.2020.547102

Introduction

Gastric cancer ranks as the fifth most common cancer and the second leading cause of cancer-related deaths. Multifocal atrophic gastritis and gastric intestinal metaplasia (GIM) often coexist and are both associated with the risk of developing gastric cancer, with GIM being the first irreversible mucosal transformation to cancer. Endoscopic surveillance was associated with earlier cancer detection and improved survival. This study aims to evaluate the prevalence, epidemiological characteristics, and clinical features of patients with GIM.

Aims & Methods

This is a single-center, retrospective study from January 1, 2022 to December 31, 2023. Including patients aged ≥18 years who underwent esophagogastroduodenoscopy (EGD) with gastric biopsies confirming GIM, All identified cases of GIM were reviewed by gastrointestinal pathologists to confirm the diagnosis. Th primary outcome was to assess the prevalence, epidemiological characteristic, and clinical features of GIM. The secondary outcome was to evaluate adherence to recommended surveillance protocols for GIM.

Results

Among 3,663 patients who underwent EGD, GIM was identified in (4.17%, n=153). The mean age of patients with GIM was 60 years, Males represented more than half of patients (54.2%), the majority were classified as overweight (Body mass index (BMI) 25–29.9; 64%, n=97) or obese (BMI ≥30; 24.3%, n=37).Smoking was reported in (17.6%, n=27), while (5.2%, n=8) reported alcohol consumption. Moreover, (7.2%, n=11) had a history of prior gastric surgeries. Dyspepsia (33.3%) was the most common indication for EGD. Gastritis was the predominant endoscopic finding and the primary reason for performing gastric biopsies (73%, n=112 ).The most common GIM subtype was complete (52%), followed by incomplete (37%) and mixed (11%). In terms of GIM location, extensive GIM was observed in (28.7%), localized GIM in (17.6%), while the location remained unknown in (53.6%) due to the lack of a follow-up EGD for mapping. Coexisting autoimmune atrophic gastritis was observed in (12.4%, n=19), Helicobacter pylori infection was detected in (16.3%, n=25). Furthermore, Dysplasia was identified in (2.6%, n=4), with low-grade dysplasia and high-grade dysplasia each accounting for (1.3%, n=2) (Table 1). Three patients developed.gastric cancer (2%) , while (4.6%, n=7) were found to have neuroendocrine tumors (NET). First degree family history of gastric cancer was reported in (12.4%, n=19).

Conclusion

This study highlights a 4.17% prevalence of GIM among patients who underwent EGD. High BMI and male sex were observed in more than half of the patients. Dysplasia was detected in 2.6%, gastric cancer in 2%, and NET in 4.6% of cases. Many patients lacked follow-up EGD surveillance, limiting effective monitoring. Larger studies with extended follow-up are required to further investigate these associations and their clinical implications.

Introduction

The Wnt/β-catenin signalling is frequently deregulated in colorectal cancer (CRC); indeed, germ-line (as found in familial adenomatous polyposis – FAP) or somatic loss of function of the APC gene represent crucial events in CRC onset. Importantly the PI3K/mTOR pathway is frequently impaired in CRC development and closely involved together with Wnt/β-catenin signalling in self-renewal and homeostasis of intestinal stem cells (1,2). Numerous inhibitors of Wnt/β-catenin and PI3K/mTOR pathways have been proposed as potential anti-cancer treatments (3,4), but long-term exposure often fails due to toxicity or the acquisition of resistance, usually associated with the activation of the non-inhibited pathway due to their mutual regulation (5).

Aims & Methods

The aim of the study was to evaluate the effect of a combination (RDE) of Rapamycin, ω3-PUFA Docosahexaenoic Acid (DHA) and epigallocatechin-3-gallate (EGCG) on PI3K/mTOR and Wnt/β-catenin pathways, in order to define an effective combinatorial approach for CRC prevention through simultaneous suppression of both pathways.
For this purpose RDE was tested for 24 or 48 hours (in cell lines and intestinal organoids, respectively) in selected different genetic backgrounds: (i) APC-mutated settings consisting of cell lines SW480 and HT-29, and intestinal organoids from four FAP patients morphologically normal-appearing mucosa (NM); (ii) non-APC-mutated CRC settings comprising HCT116 (CTNNB1 mutated) cell line and sporadic CRC organoids (CRC1: TP53 mutated; CRC2: PI3KCA and TP53 mutated); HEK293STF cell line and three healthy patients NM-derived organoids as non-mutated settings (iii). We evaluated cells and organoids viability, markers of intestinal stemness (LGR5) and differentiation (KRT20), and we analyzed the expression of target genes and effector proteins of the Wnt/β-catenin and PI3K/mTOR pathways by RT-qPCR and Western-blot.

Results

We found that RDE strongly inhibited PI3K/mTOR by downregulating the protein expression of phospho-P70S6K and phospho-S6R in all tested genetic backgrounds. FAP NM organoids responded to RDE similarly to HEK293STF cell line and the healthy organoids, with increased translocation of β-catenin into the nucleus. In contrast, in the APC-mutated SW480 and HT-29 cell lines, RDE inactivated the Wnt/β-catenin pathway, inhibiting β-catenin nuclear translocation despite the downregulation of APC and AXIN1. These findings were replicated in HCT116 cell line, that also showed reduced cell viability and induction of apoptosis. On the other hand, in non-APC-mutated CRC organoids, RDE showed a mild downregulation of Wnt/β-catenin pathway. Importantly, RDE significantly suppressed LGR5 and induced KRT20 gene expression. Finally, independently from the genetic backgrounds, exposing organoids to RDE led to increased expression of c-MYC.

Conclusion

We found that the dual inhibition of PI3K/mTOR and Wnt/β-catenin pathways by RDE is influenced by genetic backgrounds. Our approach was effective in CRC cell lines and in organoids by affecting markers of intestinal stemness and tissue differentiation, suggesting a potential therapeutic approach for both preventive and therapeutic strategies against CRC.

References

1. Krausova M, Korinek V. Wnt signaling in adult intestinal stem cells and cancer. Cell Signal. 2014 Mar;26(3):570-9. doi: 10.1016/j.cellsig.2013.11.032. Epub 2013 Dec 2. PMID: 24308963.

2. Mossmann D, Park S, Hall MN. mTOR signalling and cellular metabolism are mutual determinants in cancer. Nat Rev Cancer. 2018 Dec;18(12):744-757. doi: 10.1038/s41568-018-0074-8. PMID: 30425336.

3. Zhao H, Ming T, Tang S, Ren S, Yang H, Liu M, Tao Q, Xu H. Wnt signaling in colorectal cancer: pathogenic role and therapeutic target. Mol Cancer. 2022 Jul 14;21(1):144. doi: 10.1186/s12943-022-01616-7. PMID: 35836256.

4. Magaway C, Kim E, Jacinto E. Targeting mTOR and Metabolism in Cancer: Lessons and Innovations. Cells. 2019 Dec 6;8(12):1584. doi: 10.3390/cells8121584. PMID: 31817676.

5. Prossomariti A, Piazzi G, Alquati C, Ricciardiello L. Are Wnt/β-Catenin and PI3K/AKT/mTORC1 Distinct Pathways in Colorectal Cancer? Cell Mol Gastroenterol Hepatol. 2020;10(3):491-506. doi: 10.1016/j.jcmgh.2020.04.007. Epub 2020 Apr 22. PMID: 32334125.

Introduction

Adenomatous polyposis syndromes comprise familial adenomatous polyposis (FAP), linked to a mutation in the APC gene, and MUTYH-associated polyposis (MAP), when there is a biallelic mutation in the MUTYH gene. These conditions result in a high risk of colorectal and duodenal cancers, with well-established recommendations for screening and preventive treatment for these locations. Recent studies also suggest an increased incidence of gastric cancer in these patients, associated with different types of dysplastic lesions in contact or at distance from the classic fundic gland polyps (FGP).

Aims & Methods

The aim of this study was to determine the prevalence, treatment, and follow-up of gastric dysplastic lesions in patients with an adenomatous polyposis syndrome.
We retrospectively analysed clinical and endoscopic data from all patients with adenomatous polyposis syndrome (FAP or MAP) who underwent follow-up esophagogastroduodenoscopy (EGD) in our center, between January 2015 and May 2022. Data was collected from a national prospective database of patients with digestive polyposis diseases created in 2011. We distinguished two types of dysplastic lesions: on the one hand, well-defined umbilicated sessile nodules of the antrum, and on the other hand, whitish flat lesions showing a "blue crest" sign in NBI, often fundic and within FGPs.

Results

A total of 227 patients were included. Thirteen (5.7%) presented a MUTYH mutation. Twenty-seven patients (11.9%) had gastric dysplasia (with 17 (63%) women and a mean age of 52 [23-68] years), located proximally in 70.4% of cases and mostly corresponding to low-grade dysplasia (18 cases, 66.7%), followed by high-grade dysplasia (8 cases, 29.6%) and 1 case of cancer (3.7%). One patient died of metastatic gastric cancer not detected by endoscopy, within a very dense fundic polyposis. None of these patients had an Helicobacter pylori (HP) infection (vs 13 (6.5%) in the control group). Whitish flat areas of the proximal stomach were observed in 27 (11.9%) patients, with confirmed (low-grade) dysplasia in 17 cases (63%). Sessile antral lesions were reported in 21 cases (9.2%), with confirmed dysplasia in 6 (29%). One of the flat fundic lesions was already invasive adenocarcinoma (pT2). Three other cases of dysplasia were revealed by systematic biopsies. The presence of fundic whitish flat lesions was strongly correlated with the presence of dysplasia (relative risk of 31 (95% CI [12.7-74.9], p <0.001)). The mean age and smoking were significantly higher in the dysplasia group (p <0.001). In multivariate analysis, smokers or patients with high-density FGPs (>50) had a significantly higher risk of gastric dysplasia (absolute risk of 13.08, 95% CI [2.67-64.10] and 22.06, 95% CI [4.28-113.58], respectively). Among the cases of dysplasia, 21 (77.8%) were treated by endoscopic resection, mostly ESD (10 cases (47.6%), for lesions with a median diameter of 62.5 [35-160] mm). One of these patients had a deeply invasive pT2 adenocarcinoma and therefore received systemic treatment. A patient with multiple and extensive adenomatous lesions was referred for gastrectomy, which he refused. The remaining patients are still under endoscopic surveillance. The median follow-up duration after treatment was 21 [0-72] months, with 2 proximal recurrences (7%, low grade dysplasia) treated endoscopically.

Conclusion

We present one of the largest gastric follow-up cohorts of patients with familial polyposis, with a non-negligible frequency of gastric dysplasia and risk of cancer. The latter is possibly preventable by endoscopic resection if the dysplasia is recognized early. This accentuates the importance of educating gastroenterologists on recognizing these sometimes very difficult to see lesions (dyschromic flat lesions).

Introduction

Germline truncating variants in the CTNNA1 gene, encoding ⍺E-catenin, account for approximately 2% of hereditary diffuse gastric cancer (HDGC) cases. Signet-ring-cell (SRC) / poorly-cohesive (diffuse) gastric cancer (GC) with loss of ⍺E-catenin expression has been reported on a case-by-case basis in carriers of germline CTNNA1 variants. However, there is a knowledge gap regarding the detailed histopathological and immunohistochemical features of CTNNA1-associated GCs.

Aims & Methods

Eleven tumour samples, including six primary GCs and five (peritoneal and nodal) metastases, from nine CTNNA1 truncating carriers fulfilling the 2020 HDGC genetic testing criteria [doi:10.1016/S1470-2045(20)30219-9] were studied. Immunohistochemistry for ⍺E-catenin (clone EP1793Y) was performed on eight samples from seven patients.

Results

Median age at GC diagnosis was 48 years (range:37–75). One case was detected at early stage (pT1a) in a prophylactic total gastrectomy, while the remaining eight were diagnosed at advanced stage (≥pT2), including five with metastatic disease.
The pT1a carcinoma, adjacent to pagetoid spread of SRCs (pTis), showed classic SRCs. Advanced-stage GCs showed predominantly poorly-cohesive morphology with variable SRC component: <5% in five cases, 5–10% in two, and 10–50% in three. In two patients, the SRC proportion increased from 10% in primary tumours to 50% in corresponding metastases. All metastatic sites showed purely poorly-cohesive morphology with prominent desmoplastic stroma. In contrast, primary tumours displayed additional patterns, including nested, trabecular, rosetoid and true microglandular structures.
All tumours demonstrated aberrant ⍺E-catenin expression: complete loss in 63% (5/8) of samples analysed, and faint/incomplete membranous, paranuclear dotted, and/or cytoplasmic staining in the remaining 37% (3/8).

Conclusion

This is the largest cohort to date characterizing histopathological features and ⍺E-catenin expression in CTNNA1-associated GCs. The morphological diversity observed in primary tumours may represent a diagnostic pitfall in the recognition of HDGC cases. The possible utility of ⍺E-catenin expression as a marker for genetic triage in these cases warrants further investigation.

References

1. van der Sluis L, van Dieren JM, van der Post RS, Bisseling TM. Current advances and challenges in Managing Hereditary Diffuse Gastric Cancer (HDGC): a narrative review. Hered Cancer Clin Pract. 2024 Oct 8;22(1):21. doi: 10.1186/s13053-024-00293-5. PMID: 39379994
2. Lobo S, Benusiglio PR, Coulet F, Boussemart L, Golmard L, Spier I, Hüneburg R, Aretz S, Colas C, Oliveira C. Cancer predisposition and germline CTNNA1 variants. Eur J Med Genet. 2021 Oct;64(10):104316. doi: 10.1016/j.ejmg.2021.104316
3. Coudert M, Drouet Y, Delhomelle H, Svrcek M, Benusiglio PR, Coulet F, Clark DF, Katona BW, van Hest LP, van der Kolk LE, Cats A, van Dieren JM, Nehoray B, Slavin T, Spier I, Hüneburg R, Lobo S, Oliveira C, Boussemart L, Masson L, Chiesa J, Schwartz M, Buecher B, Golmard L, Bouvier AM, Bonadona V, Stoppa-Lyonnet D, Lasset C, Colas C. First estimates of diffuse gastric cancer risks for carriers of CTNNA1 germline pathogenic variants. J Med Genet. 2022 Dec;59(12):1189-1195. doi: 10.1136/jmg-2022-108740. Epub 2022 Aug 29. PMID: 36038258.
4. Gullo I, van der Post RS, Carneiro F. Recent advances in the pathology of heritable gastric cancer syndromes. Histopathology. 2021 Jan;78(1):125-147. doi: 10.1111/his.14228. PMID: 33382491.

Introduction

Autoimmune atrophic gastritis (AAG) is an immune-mediated disorder characterized by corpus oxyntic mucosa atrophy and impaired gastric acid secretion(1,2). The increased gastric cancer (GC) risk in AAG is still debated. One mechanism favoring gastric carcinogenesis may be increased intragastric pH leading to intragastric microenvironment changes and facilitating bacterial dysbiosis(3-5). Oral microbiota and periodontal-dental disorders alterations have been linked to increased GC risk as well(6-8). In AAG, the increased intragastric pH may lead to survival of swallowed bacteria, possibly further contributing to the increased GC risk. The oral and gastric microbiota composition together have not been investigated so far in AAG patients.

Aims & Methods

The aim of the study was to investigate the oral and gastric microbiota composition in AAGpts in order to clarify the role of oral bacteria in gastric dysbiosis.
We conducted a case-control study: n=20 histologically diagnosed AAGpts(F75%,age 64 yrs) and n=20 ctrs with healthy stomach(HS)(F45%,age 56 yrs). From all pts and ctrs a sputum sample was obtained in the morning fasting without tooth brushing. Within 1 hour after sputum collection, pts and ctrs underwent gastroscopy with biopsies (updated Sydney system) for histopathological assessment and one further corpus biopsy for DNA extraction. Sputum(n=40) and biopsy(n=40) samples were collected in vials with DNA shield and frozen at -20°C since processing. DNA was extracted (QIAmp DNA kit) and prepared (Illumina Nextera XT DNA Library Preparation Kit). Paired-end sequencing was performed (Illumina MiSeq sequencer,MiSeq Reagent Kit v3). Fastq files were filtered to remove low-quality reads; filtered reads were taxonomically classified and subjected to Homo sapiens filtering (METAnnotatorX2 pipeline, up-to-date RefSeq database, NCBI).

Results

AAGpts and ctrs were similar with regard to clinical features, oral hygiene and paraodontal-dental disorders. Bacterial abundance in biopsies was higher in AAGpts than in ctrs (403 vs 223,p=0.06), but not different in sputum (27,728 vs 31,544,p=0.54). On biopsies, AAGpts showed a lower Shannon Index than ctrs (2.553 vs 2.617, p=0.001). On sputum, AAGpts showed a higher Shannon Index than ctrs (2.828 vs 2.738, p=0.0). Beta-diversity (Bray-Curtis dissimilarity) was not different between pts and ctrs, neither in sputum nor biopsies.
At the taxa level, in biopsies Streptococcus oralis, Fusobacterium pseudoperiodonticum, Veillonella rogosae, and Gemella sanguinis were significantly associated with pts(p<0.03); while in sputum the most significant associations were G.sanguinis, Prevotella multisaccharivorax, F.nucleatum, and F.peridonticum(p<0.03). The most abundantly shared taxa between sputum and biopsy were S.oralis and P.histicola, while G.sanguinis, F.pseudoperidonticum, and V.rogosae were shared in pts only.

Conclusion

This study confirmed gastric dysbiosis in AAG as shown by lower biodiversity and evenness. Gastric bacterial abundance was higher in AAG, probably due to non-acidic gastric pH permitting overgrowth of gastric bacteria. Oral bacterial abundance was similar in AAG and ctr with higher biodiversity-evenness in AAG pts, probably due to upstream passage of unactivated bacteria from stomach to mouth. Oral taxa related to increased GC risk were more commonly associated to AAG and shared between mouth and stomach. In AAG these findings show the role of oral microbiota in gastric dysbiosis, possibly contributing to increased GC risk.

References

1) Lenti MV,Rugge M,Lahner E,Miceli E,Toh BH,Genta RM,De Block C,Hershko C,Di Sabatino A. “Autoimmune gastritis” Nat Rev Dis Primers. 2020 Jul 9;6(1):56.
2) Rugge M,Genta RM,Malfertheiner P,Dinis-Ribeiro M,El-Serag H,Graham DY,Kuipers EJ,Leung WK,Park JY,Rokkas T,Schulz C,El-Omar EM;RE.GA.IN;the Real-world Gastritis Initiative-updating the updates. Gut. 2024 Feb 23;73(3):407-441. doi: 10.1136/gutjnl-2023-331164. PMID: 38383142.
3) Conti L, Annibale B, Lahner E. Autoimmune Gastritis and Gastric Microbiota. Microorganisms. 2020;8(11):1827. Published 2020 Nov 19. doi:10.3390/microorganisms8111827
4) Lin L, Li W, Yan L, et al. Comparison of gastric microbiota in patients with different gastric lesions in high and low risk areas of gastric cancer. BMC Microbiol. 2025;25(1):202. Published 2025 Apr 9. doi:10.1186/s12866-025-03926-4
5) Conti L, Borro M, Milani C, et al. Gastric microbiota composition in patients with corpus atrophic gastritis. Dig Liver Dis. 2021;53(12):1580-1587. doi:10.1016/j.dld.2021.05.005
6) Huang C, Li Y, He C. Oral microbes and gastrointestinal cancers: new strategies and insights. Clin Transl Oncol. Published online April 5, 2025. doi:10.1007/s12094-025-03891-4
7) Xia R, Jiang Z, Zhou Y, et al. Oral microbiota and gastric cancer: recent highlights and knowledge gaps. J Oral Microbiol. 2024;16(1):2391640. Published 2024 Aug 16. doi:10.1080/20002297.2024.2391640
8) Aguiar FJN, Menezes FDS, Fagundes MA, et al. Gastric adenocarcinoma and periodontal disease: A systematic review and meta-analysis. Clinics (Sao Paulo). 2024;79:100321. Published 2024 Jan 31. doi:10.1016/j.clinsp.2023.100321

Introduction

Autoimmune gastritis (AIG) is the basis of gastric cancer (GC). Loss of parietal cells (PCs) causes the development of spasmolytic polypeptide-expressing metaplasia (SPEM), which is considered as important precancerous lesion. Previously, we demonstrated that parietal cell-specific Slc26a9 deficiency caused spontaneous SPEM to GC in mice (Liu et al., Cellular oncology; 2022; Liu et al., DDW2023, 2024). The present study was undertaken to study a potential role of Slc26a9 downregulation in the development of AIG and how to progress to SPEM.

Aims & Methods

The present study was undertaken to study a potential role of Slc26a9 downregulation in the development of AIG and how to progress to SPEM.
Slc26a9^fl/fl mice were crossed with H⁺-K⁺-Atp4b-Cre to produce the PCs-specific Slc26a9 knockout in Slc26a9^fl/fl/Atp4b-Cre mice in a mixed genomic background. Electron microscope, flow cytometry analysis, histopathological and immunohistochemical (IHC) analysis with specific markers were performed in Slc26a9^fl/fl and Slc26a9^fl/fl/Atp4b-Cre mice.

Results

Compared with Slc26a9^fl/fl mice, Slc26a9^fl/fl/Atp4b-Cre mice exhibited strongly loss of parietal cells, oxyntic atrophy followed with lymphocyte infiltration,
the mitochondria of PCs were significantly swollen, the cell membrane structure was blurred and damaged, and the cristae were broken and disappeared which was observed by electron microscope. Furthermore, Slc26a9 deletion showed an accumulation of multiple pyroptosis factors, including of NRLP3, Caspase-1, ASC, Gasdermin D, IL-1β and IL-18, and activated Gasdermin D binded to mitochondrial cardiolipin and led to the release of mitochondrial mediators, including ACO2, Cyto C, indicating that mitochondrial damage related pyroptosis of PCs. Moreover, Flow cytometry analysis showed that CD4+ Tcells that infiltrated the Slc26a9^fl/fl/Atp4b-Cre stomach expressed the TCR (TCRVα2/TCRVβ2) specific for the H⁺/K⁺-ATPase peptide, followed with upregulation of CD4+ T mediated cytokines, including IFN-γ, IL-2, IL-11 and IL-17. Taken together, PCs selective Slc26a9 deletion in mice caused Gasdermin D mediates mitochondrial damage induced PCs initial loss, resulted in the development of AIG. Furthermore, Slc26a9^fl/fl/Atp4b-Cre mice showed that hypergastrinemia induced Tuft cell migration and mediated IL-25 release, followed with upregulation of ILC2 cell marker GATA3 and M2 macrophage polarized markers F4/80 and CD163 in the base of gastric mucosal of Slc26a9^fl/fl /Atp4b-Cre mice, indicating that PCs selective Slc26a9 deletion in mice caused PCs pyroptosis and followed with gastric regional immunity remodeling, resulted in the development of SPEM based on AIG.

Conclusion

PCs-selective Slc26a9 deletion in mice caused Gasdermin D mediates mitochondrial damage induced PC cells initial loss, and followed with activation of IL-25-ILC2-M2 macrophage axis, which is the key event to induce spontaneous AIG and progress to SPEM.