Interleukin-1β Suppresses Gastrin via Primary Cilia and Induces Antral Hyperplasia

Current study of pathogenetic mechanisms and therapeutics of chronic atrophic gastritis: a comprehensive review

Chronic atrophic gastritis (CAG) is a prevalent digestive system disease characterized by atrophy of the gastric mucosa and the disappearance of inherent gastric glands. According to the theory of Correa's cascade, CAG is an important pathological stage in the transformation from normal condition to gastric carcinoma. In recent years, the global incidence of CAG has been increasing due to pathogenic factors, including Helicobacter pylori infection, bile reflux, and the consumption of processed meats. In this review, we comprehensively described the etiology and clinical diagnosis of CAG. We focused on elucidating the regulatory mechanisms and promising therapeutic targets in CAG, with the expectation of providing insights and theoretical support for future research on CAG.

Surface electric field enhanced biosensor based on symmetrical U-tapered HCF structure for gastric carcinoma biomarker trace detection

In this article, a novel U-tapered hollow-core fiber (HCF) surface plasmon resonance (SPR) biosensor coated with PtS2 for early-stage gastric carcinoma (GC) diagnosis was demonstrated. The article proposed the first investigation to detect Interleukin-10 (IL10) and Interleukin-1β (IL1β) which were associated with the risk of developing gastric carcinoma, using optical fiber SPR technology. Herein, the sensitivity of sensor was effectively improved through a combination of tapered and U-shaped structures. Additionally, to further enhance the detection capability, two-dimensional material PtS2 was utilized to increase the surface electric field intensity of the sensor. Simultaneously, optimization of structural parameters such as taper ratio, bending diameters, and Au film thickness was conducted. Ultimately, the designed sensor achieved a remarkable sensitivity of 13210 nm/RIU within the refractive index (RI) range of 1.33-1.37. The sensor demonstrated exceptional performance, achieving sensitivities of 3.64 nm/(ng/ml) and 7.46 nm/(ng/ml) for the detection of IL10 and IL1β biomarkers, respectively, along with limit of detection (LOD) of 2.74 pg/ml and 1.33 pg/ml, and successfully detecting the presence of these biomarkers in the serum of gastric cancer patients. Overall, the proposed sensor exhibits significant potential in early gastric cancer detection and advances the application of optical fiber SPR sensors in trace biodetection.

The bHLH transcription factor ASCL1 promotes differentiation of endocrine cells in the stomach and is regulated by Notch signaling

Notch signaling regulates gastrointestinal stem cell proliferation and differentiation yet Notch-regulated transcriptional effectors of gastric epithelial cell differentiation are poorly understood. Here we tested the role of the bHLH transcription factor Achaete-Scute homolog 1 (ASCL1) in gastric epithelial cell differentiation, and its regulation by Notch. Newborn Ascl1 null mice showed a loss of expression of markers of neurogenin-3-dependent enteroendocrine cells, with normal expression of enterochromaffin-like cells, mucous cells, chief cells, and parietal cells. In adult mice, Ascl1 gene expression was observed in the stomach, but not the intestine, with higher expression in antral than corpus epithelium. Lineage tracing in Ascl1-CreERT2; Rosa26-LSL-tdTomato mice revealed single, scattered ASCL1+ cells in the gastric epithelium, demonstrating expression in antral gastrin- and serotonin-producing endocrine cells. ASCL1-expressing endocrine cells persisted for several weeks posttamoxifen labeling with a half-life of approximately 2 months. Lineage tracing in Gastrin-CreERT2 mice demonstrated a similar lifespan for gastrin-producing cells, confirming that gastric endocrine cells are long-lived. Finally, treatment of Ascl1-CreERT2; Rosa26-LSL-tdTomato mice with the pan-Notch inhibitor dibenzazepine increased the number of lineage-labeled cells in the gastric antrum, suggesting that Notch signaling normally inhibits Ascl1 expression. Notch regulation of Ascl1 was also demonstrated in a genetic mouse model of Notch activation, as well as Notch-manipulated antral organoid cultures, thus suggesting that ASCL1 is a key downstream Notch pathway effector promoting endocrine cell differentiation in the gastric epithelium.NEW & NOTEWORTHY Although Notch signaling is known to regulate cellular differentiation in the stomach, downstream effectors are poorly described. Here we demonstrate that the bHLH transcription factor ASCL1 is expressed in endocrine cells in the stomach and is required for formation of neurogenin-3-dependent enteroendocrine cells but not enterochromaffin-like cells. We also demonstrate that Ascl1 expression is inhibited by Notch signaling, suggesting that ASCL1 is a Notch-regulated transcriptional effector directing enteroendocrine cell fate in the mouse stomach.

Clinically Defined Mutations in MEN1 Alter Its Tumor-suppressive Function Through Increased Menin Turnover

Loss of the tumor suppressor protein menin is a critical event underlying the formation of neuroendocrine tumors (NET) in hormone-expressing tissues including gastrinomas. While aberrant expression of menin impairs its tumor suppression, few studies explore the structure-function relationship of clinical multiple endocrine neoplasia, type 1 (MEN1) mutations in the absence of a complete LOH at both loci. Here, we determined whether clinical MEN1 mutations render nuclear menin unstable and lead to its functional inactivation. We studied the structural and functional implications of two clinical MEN1 mutations (R516fs, E235K) and a third variant (A541T) recently identified in 10 patients with gastroenteropancreatic (GEP)-NETs. We evaluated the subcellular localization and half-lives of the mutants and variant in Men1-null mouse embryo fibroblast cells and in hormone-expressing human gastric adenocarcinoma and NET cell lines. Loss of menin function was assessed by cell proliferation and gastrin gene expression assays. Finally, we evaluated the effect of the small-molecule compound MI-503 on stabilizing nuclear menin expression and function in vitro and in a previously reported mouse model of gastric NET development. Both the R516fs and E235K mutants exhibited severe defects in total and subcellular expression of menin, and this was consistent with reduced half-lives of these mutants. Mutated menin proteins exhibited loss of function in suppressing tumor cell proliferation and gastrin expression. Treatment with MI-503 rescued nuclear menin expression and attenuated hypergastrinemia and gastric hyperplasia in NET-bearing mice. Clinically defined MEN1 mutations and a germline variant confer pathogenicity by destabilizing nuclear menin expression.

Significance

We examined the function of somatic and germline mutations and a variant of MEN1 sequenced from gastroenteropancreatic NETs. We report that these mutations and variant promote tumor cell growth and gastrin expression by rendering menin protein unstable and prone to increased degradation. We demonstrate that the menin-MLL (mixed lineage leukemia) inhibitor MI-503 restores menin protein expression and function in vitro and in vivo, suggesting a potential novel therapeutic approach to target MEN1 GEP-NETs.

Weierning, a Chinese patent medicine, improves chronic atrophic gastritis with intestinal metaplasia

ETHNOPHARMACOLOGICAL RELEVANCE

Weierning tablet (WEN) is a traditional Chinese patent medicine widely used in clinical for chronic atrophic gastritis (CAG) therapy for years. However, the underlying mechanisms of WEN on anti-CAG are still unveiled.

AIM OF THE STUDY

The present study aimed to elucidate the characteristic function of WEN on anti-CAG and to illuminate its potential mechanism.

METHODS

The CAG model was established by gavage rats with a modeling solution (consisting of 2% sodium salicylate and 30% alcohol) with irregular diets and free access to 0.1% ammonia solution for two months on end. An enzyme-linked immunosorbent assay was used to measure the serum levels of gastrin, pepsinogen, and inflammatory cytokines. qRT-PCR was applied to measure mRNA expressions of IL-6, IL-18, IL-10, TNF-α, and γ-IFN in gastric tissue. Pathological changes and the ultrastructure of gastric mucosa were examined by hematoxylin and eosin staining and transmission electron microscopy, respectively. AB-PAS staining was applied to observe the intestinal metaplasia of gastric mucosa. Immunohistochemistry and Western blot were used to measure the expression levels of mitochondria apoptosis-related proteins and Hedgehog pathway-related proteins in gastric tissues. Expressions of Cdx2 and Muc2 protein were determined by immunofluorescent staining.

RESULTS

WEN could dose-dependently lower the serum level of IL-1β and the mRNA expressions of IL-6, IL-8, IL-10, TNF-α, and γ-IFN in gastric tissue. Also, WEN significantly alleviated the collagen deposition in gastric submucosa, regulated the expressions of Bax, Cleaved-caspase9, Bcl2, and Cytochrome c to reduce the apoptosis of gastric mucosa epithelial cells, and maintained the integrity of the gastric mucosal barrier. Moreover, WEN could reduce protein expressions of Cdx2, Muc2, Shh, Gli1, and Smo, and reverse intestinal metaplasia of gastric mucosa to block the progress of CAG.

CONCLUSION

This study demonstrated a positive effect of WEN on improving CAG and reverse intestinal metaplasia. These functions were related to the suppression of gastric mucosal cells' apoptosis and the inhibition of Hedgehog pathways' activation.

A comprehensive evaluation of an animal model for Helicobacter pylori-associated stomach cancer: Fact and controversy

Even though Helicobacter pylori infection was the most causative factor of gastric cancer, numerous in vivo studies failed to induce gastric cancer using H. pylori infection only. The utilization of established animal studies in cancer research is crucial as they aim to investigate the coincidental association between suspected oncogenes and pathogenesis as well as generate models for the development and testing of potential treatments. The methods to establish gastric cancer using infected animal models remain limited, diverse in methods, and showed different results. This study investigates the differences in animal models, which highlight different pathological results in gaster by literature research. Electronic databases searched were performed in PubMed, Science Direct, and Cochrane, without a period filter. A total of 135 articles were used in this study after a full-text assessment was conducted. The most frequent animal models used for gastric cancer were Mice, while Mongolian gerbils and Transgenic mice were the most susceptible model for gastric cancer associated with H. pylori infection. Additionally, transgenic mice showed that the susceptibility to gastric cancer progression was due to genetic and epigenetic factors. These studies showed that in Mongolian gerbil models, H. pylori could function as a single agent to trigger stomach cancer. However, most gastric cancer susceptibilities were not solely relying on H. pylori infection, and numerous factors are involved in cancer progression. Further study using Mongolian gerbils and Transgenic mice is crucial to conduct and establish the best models for gastric cancer associated H. pylori.

IL-1 Polymorphism and Helicobacter pylori Infection Features: Highlighting VNTR's Potential in Predicting the Susceptibility to Infection-Associated Disease Development

Genetic polymorphisms at the IL-1 cluster are associated with increased Helicobacter pylori (H. pylori)-associated disease risk in an ethnically dependent manner. Due to the corroborated role of IL-1β in H. pylori infection progression, our aim is to depict the impact of IL1B rs1143627 and rs16944 as well as the IL1RN variable number of identical tandem repeats (VNTR) on the clinical and biological features of Moroccan H. pylori-infected patients. A total of 58 patients with epigastralgic pain were referred to the gastroenterology department for histopathological and clinical analysis. DNA extraction from antrum and fundus biopsies and PCR-RFLP were performed to detect polymorphisms. As a result, VNTR was significantly associated with IL-1β antrum levels (p-value = 0.029), where the *1/*4 genotype showed a positive association with upregulated cytokine levels in the antrum and was clustered with H. pylori-infected patients' features and higher levels of IL-1β in the antrum and fundus. Likewise, *1/*1 genotype carriers clustered with severe gastritis activity and H. pylori density scores along with low levels of IL-1β in the antrum and fundus, while the *1/*2 genotype was clustered with non-infected-patient features and normal IL-1β levels. In conclusion, VNTR might be an interesting predictor to identify patients at risk of developing H. pylori-associated pathologies.

GFAP-directed Inactivation of Men1 Exploits Glial Cell Plasticity in Favor of Neuroendocrine Reprogramming

BACKGROUND & AIMS

Efforts to characterize the signaling mechanisms that underlie gastroenteropancreatic neoplasms (GEP-NENs) are precluded by a lack of comprehensive models that recapitulate pathogenesis. Investigation into a potential cell-of-origin for gastrin-secreting NENs revealed a non-cell autonomous role for loss of menin in neuroendocrine cell specification, resulting in an induction of gastrin in enteric glia. Here, we investigated the hypothesis that cell autonomous Men1 inactivation in glial fibrillary acidic protein (GFAP)-expressing cells induced neuroendocrine differentiation and tumorigenesis.

METHODS

Transgenic GFAP^ΔMen1 mice were generated by conditional GFAP-directed Men1 deletion in GFAP-expressing cells. Cre specificity was confirmed using a tdTomato reporter. GFAP^ΔMen1 mice were evaluated for GEP-NEN development and neuroendocrine cell hyperplasia. Small interfering RNA-mediated Men1 silencing in a rat enteric glial cell line was performed in parallel.

RESULTS

GFAP^ΔMen1 mice developed pancreatic NENs, in addition to pituitary prolactinomas that phenocopied the human MEN1 syndrome. GFAP^ΔMen1 mice exhibited gastric neuroendocrine hyperplasia that coincided with a significant loss of GFAP expression. Men1 deletion induced loss of glial-restricted progenitor lineage markers and an increase in neuroendocrine genes, suggesting a reprogramming of GFAP⁺ cells. Deleting Kif3a, a mediator of Hedgehog signaling, in GFAP-expressing cells attenuated neuroendocrine hyperplasia by restricting the neuroendocrine cell fate. Similar results in the pancreas were observed when Sox10 was used to delete Men1.

CONCLUSIONS

GFAP-directed Men1 inactivation exploits glial cell plasticity in favor of neuroendocrine differentiation.

The immune microenvironment in gastric adenocarcinoma

Like most solid tumours, the microenvironment of epithelial-derived gastric adenocarcinoma (GAC) consists of a variety of stromal cell types, including fibroblasts, and neuronal, endothelial and immune cells. In this article, we review the role of the immune microenvironment in the progression of chronic inflammation to GAC, primarily the immune microenvironment driven by the gram-negative bacterial species Helicobacter pylori. The infection-driven nature of most GACs has renewed awareness of the immune microenvironment and its effect on tumour development and progression. About 75-90% of GACs are associated with prior H. pylori infection and 5-10% with Epstein-Barr virus infection. Although 50% of the world's population is infected with H. pylori, only 1-3% will progress to GAC, with progression the result of a combination of the H. pylori strain, host susceptibility and composition of the chronic inflammatory response. Other environmental risk factors include exposure to a high-salt diet and nitrates. Genetically, chromosome instability occurs in ~50% of GACs and 21% of GACs are microsatellite instability-high tumours. Here, we review the timeline and pathogenesis of the events triggered by H. pylori that can create an immunosuppressive microenvironment by modulating the host's innate and adaptive immune responses, and subsequently favour GAC development.

The TNF-Alpha Inducing Protein is Associated With Gastric Inflammation and Hyperplasia in a Murine Model of Helicobacter pylori Infection

Helicobacter pylori (H. pylori) is a Gram-negative bacterium that colonizes the human stomach leading to the development of chronic gastritis, peptic ulcers and gastric adenocarcinoma. A combination of host, environment and bacterial virulence factors contribute to disease development. The H. pylori TNFα inducing protein (Tipɑ) is a virulence factor shown to induce multiple pro-inflammatory cytokines in addition to TNFα in vitro. The goal of the present study was to elucidate the role of Tipα in promoting inflammation in vivo and to identify the molecular pathways associated with Tipα associated virulence. Mice were infected with wild-type Sydney strain (SS1) or a tipα mutant (Δtipα) for 1 month and 4 months. We also completed a second 4 months infection including a 1:1 SS1 to Δtipα co-infected group in addition to SS1 and Δtipα infected groups. The expression of TNFα, and KC were significantly higher in the SS1 infected group compared to both uninfected control (naïve) and Δtipα groups. Mice infected with Tipα expressing SS1 induced more severe histological gastritis and developed hyperplasia compared to Δtipα infected mice. Microarray analysis of gastric epithelial cells co-cultured with recombinant Tipα (rTipα) demonstrates up-regulation of the NFκB pathway. This data suggest Tipα plays an important role in H. pylori induced inflammation.

Deletion of kif3a in CK19 positive cells leads to primary cilia loss, biliary cell proliferation and cystic liver lesions in TAA-treated mice

BACKGROUND & AIMS

Loss of primary cilia in epithelial cells is known to cause cystic diseases of the liver and kidney. We have previously shown that during experimental and human cirrhosis that primary cilia were predominantly expressed on biliary cells in the ductular reaction. However, the role of primary cilia in the pathogenesis of the ductular reaction is not fully understood.

METHODS

Primary cilia were specifically removed in biliary epithelial cells (BECs) by the administration of tamoxifen to Kif3a^f/f;CK19^CreERT mice at week 2 of a 20-week course of TAA treatment. Biliary progenitor cells were isolated and grown as organoids from gallbladders. Cells and tissue were analysed using histology, immunohistochemistry and Western blot assays.

RESULTS

At the end of 20 weeks TAA administration, primary cilia loss in liver BECs resulted in multiple microscopic cystic lesions within an unaltered ductular reaction. These were not seen in control mice who did not receive TAA. There was no effect of biliary primary cilia loss on the development of cirrhosis. Increased cellular proliferation was seen within the cystic structures associated with a decrease in hepatocyte lobular proliferation. Loss of primary cilia within biliary organoids was initially associated with reduced cell passage survival but this inhibitory effect was diminished in later passages. ERK but not WNT signalling was enhanced in primary cilia loss-induced cystic lesions in vivo and its inhibition reduced the expansion of primary cilia deficient biliary progenitor cells in vitro.

CONCLUSIONS

TAA-treated kif3a BEC-specific knockout mice had an unaltered progression to cirrhosis, but developed cystic lesions that showed increased proliferation.

Gastrin: From Physiology to Gastrointestinal Malignancies

Abetted by widespread usage of acid-suppressing proton pump inhibitors (PPIs), the mitogenic actions of the peptide hormone gastrin are being revisited as a recurring theme in various gastrointestinal (GI) malignancies. While pathological gastrin levels are intricately linked to hyperplasia of enterochromaffin-like cells leading to carcinoid development, the signaling effects exerted by gastrin on distinct cell types of the gastric mucosa are more nuanced. Indeed, mounting evidence suggests dichotomous roles for gastrin in both promoting and suppressing tumorigenesis. Here, we review the major upstream mediators of gastrin gene regulation, including inflammation secondary to Helicobacter pylori infection and the use of PPIs. We further explore the molecular biology of gastrin in GI malignancies, with particular emphasis on the regulation of gastrin in neuroendocrine neoplasms. Finally, we highlight tissue-specific transcriptional targets as an avenue for targetable therapeutics.

NF-κB in Gastric Cancer Development and Therapy

Gastric cancer is considered one of the most common causes of cancer-related death worldwide and, thus, a major health problem. A variety of environmental factors including physical and chemical noxae, as well as pathogen infections could contribute to the development of gastric cancer. The transcription factor nuclear factor kappa B (NF-κB) and its dysregulation has a major impact on gastric carcinogenesis due to the regulation of cytokines/chemokines, growth factors, anti-apoptotic factors, cell cycle regulators, and metalloproteinases. Changes in NF-κB signaling are directed by genetic alterations in the transcription factors themselves, but also in NF-κB signaling molecules. NF-κB actively participates in the crosstalk of the cells in the tumor micromilieu with divergent effects on the heterogeneous tumor cell and immune cell populations. Thus, the benefits/consequences of therapeutic targeting of NF-κB have to be carefully evaluated. In this review, we address recent knowledge about the mechanisms and consequences of NF-κB dysregulation in gastric cancer development and therapy.

Development of an easy-to-use urease kit for detecting Helicobacter pylori in canine gastric mucosa

BACKGROUND AND AIM

Helicobacter pylori is an important pathogen in humans and animals involved in chronic gastritis, leading to the development of gastric cancer. Urease produced by H. pylori is an enzyme that promotes bacterial colonization and can be used clinically as a biomarker of H. pylori infection as part of a rapid urease test (RUT). A test with high specificity (95-100%) would be more convenient and faster than histopathology, bacterial culture, and polymerase chain reaction (PCR). The aim of this study was to develop a simple, cheap, and fast kit for detecting H. pylori infection in the gastric mucosa of canines, which can be used in clinical practice for diagnosing infection with this bacterium.

MATERIALS AND METHODS

The RUT assays developed were prepared using 1% agar, 1% sodium phosphate monobasic, and 1% urea followed by the addition of 3% methyl red indicator. The cutoff value of sensitivity of the RUT assay was established using the urease of H. pylori ATCC 43504 and color change was monitored for 24 h. Comparisons of the sensitivity to H. pylori ATCC 43504 were made between the developed RUT assays and the Hp Fast™ commercial kit. Then, the limit of detection for H. pylori ATCC 43504 number was analyzed by the SYBR Green real-time PCR assay to measure the copy number of the ureC gene. Gastric biopsy samples from the antrum, body, and fundus of the stomach were collected from eight canines presenting with vomiting and gastroenteritis. Analyses were performed on fresh samples using the developed RUT assays and the Hp Fast™ commercial kit, which were read within 24 h; then, the results were confirmed with SYBR Green real-time PCR. The specificity of the RUT assays was tested with a number of different bacteria, including Staphylococcus pseudintermedius, Proteus spp., Pseudomonas aeruginosa, Klebsiella pneumoniae, Enterococcus spp., Escherichia coli, and Salmonella spp.; H. pylori ATCC 43504 was used as a positive control.

RESULTS

The results showed that the developed assays were sensitive to the urease enzyme at 0.1 mg/mL. The lowest detection limit of this assay for H. pylori ATCC 43504 was found to be 102 copies at 30 min. The sensitivity of detection of H. pylori in gastric biopsies of canines occurred in a minimum of 30 min. The RUT showed similar results to the Hp Fast™ commercial kit. In the developed RUT, the color change of the test from red to yellow could be clearly distinguished between the color of the positive test and the negative one; however, in the commercial Hp Fast™, it was difficult to observe the gel color changein the negative pH range of 5.8 and the positive pH of 6.5. The developed RUT was specific for H. pylori and did not detect any of the other tested bacteria. The test kit can also be stored for 6 months at 4°C.

CONCLUSION

The sensitivity of the developed assays allowed the detection of urease enzyme at a minimum concentration of 0.1 mg/mL. Our RUT could also detect H. pylori from one in eight canine specimens at a minimum of 102 copies within 30 min. This RUT is specific to H. pylori as it did not detect any of the other tested bacteria.