Alterations in gastric mucosal lineages before or after acute oxyntic atrophy in gastrin receptor and H2 histamine receptor-deficient mice

Metabolic regulator ERRγ governs gastric stem cell differentiation into acid-secreting parietal cells

Parietal cells (PCs) produce gastric acid to kill pathogens and aid digestion. Dysregulated PC census is common in disease, yet how PCs differentiate is unclear. Here, we identify the PC progenitors arising from isthmal stem cells, using mouse models and human gastric cells, and show that they preferentially express cell-metabolism regulator and orphan nuclear receptor Estrogen-related receptor gamma (Esrrg, encoding ERRγ). Esrrg expression facilitated the tracking of stepwise molecular, cellular, and ultrastructural stages of PC differentiation. EsrrgP2ACreERT2 lineage tracing revealed that Esrrg expression commits progenitors to differentiate into mature PCs. scRNA-seq indicated the earliest Esrrg+ PC progenitors preferentially express SMAD4 and SP1 transcriptional targets and the GTPases regulating acid-secretion signal transduction. As progenitors matured, ERRγ-dependent metabolic transcripts predominated. Organoid and mouse studies validated the requirement of ERRγ for PC differentiation. Our work chronicles stem cell differentiation along a single lineage in vivo and suggests ERRγ as a therapeutic target for PC-related disorders.

Exploration of mechanism of abdominal massage to promote repair of ethanol-induced gastric mucosal injury in rats based on brain-gut axis

BACKGROUND

As one of the external treatment methods of traditional Chinese medicine, abdominal massage can effectively promote the repair of gastric mucosal injury, but its mechanism is not clear. We hypothesized that abdominal massage can stimulate the hypothalamus through the brain-gut axis, result in the release of intestinal trefoil factor (ITF) to the gastric mucosa, and thus promote the repair of the gastric mucosa.

AIM

To explore the mechanism of abdominal massage to promote the repair of gastric mucosal injury, and to verify the role of the brain-gut axis in this process.

METHODS

Rats were randomly divided into an abdominal massage group, a model group, and a blank control groupp. A rat model of gastric mucosal injury was reproduced by absolute ethanol gavage. The abdominal massage group was given massage intervention every day, and the model group and the blank control group were not given any intervention. After 21 d, the expression of gastrin (GAS) and neuropeptide Y (NPY) in the colon and hypothalamus, and the content of ITF in serum were detected by ELISA. The expression of c-fos protein in the hypothalamus was detected by immunohistochemistry and Western blot. The expression of ITF mRNA in the hypothalamus and gastric mucosa was detected by real-time quantitative RT-PCR.

RESULTS

Compared with the blank control group, the contents of GAS and NPY in the hypothalamus were significantly decreased, the content of GAS in the colon was significantly decreased, the content of NPY in the colon was significantly increased, the expression of c-fos protein in the hypothalamus was significantly increased, and the content of ITF in the hypothalamus and gastric mucosa was significantly increased in the model group. After abdominal massage intervention, the contents of GAS and NPY in the colon and hypothalamus were improved, the expression of c-fos protein in the hypothalamus was significantly decreased, and the levels of ITF mRNA in the hypothalamus and serum ITF and gastric mucosa were significantly increased.

CONCLUSION

Abdominal massage can improve the contents of GAS and NPY in the colon and hypothalamus of rats with gastric mucosal injury, and regulate the central nervous system, which confirms the existence of the brain-gut axis. Abdominal massage can regulate the expression of c-fos protein in the hypothalamus, downregulate the intensity of stress response, and stimulate the hypothalamus to release ITF into blood. ITF reaching the gastric mucosa via blood circulation can promote the repair of gastric mucosal injury.

Gastric Corpus Mucosal Hyperplasia and Neuroendocrine Cell Hyperplasia, but not Spasmolytic Polypeptide-Expressing Metaplasia, Is Prevented by a Gastrin Receptor Antagonist in H+/K+ATPase Beta Subunit Knockout Mice

Proton pump inhibitor use is associated with an increased risk of gastric cancer, which may be mediated by hypergastrinemia. Spasmolytic polypeptide-expression metaplasia (SPEM) has been proposed as a precursor of gastric cancer. We have examined the effects of the gastrin receptor antagonist netazepide (NTZ) or vehicle on the gastric corpus mucosa of H⁺/K⁺ATPase beta subunit knockout (KO) and wild-type (WT) mice. The gastric corpus was evaluated by histopathology, immunohistochemistry (IHC), in situ hybridization (ISH) and whole-genome gene expression analysis, focusing on markers of SPEM and neuroendocrine (NE) cells. KO mice had pronounced hypertrophy, intra- and submucosal cysts and extensive expression of SPEM and NE cell markers in the gastric corpus, but not in the antrum. Numerous SPEM-related genes were upregulated in KO mice compared to WT mice. NTZ reduced hypertrophia, cysts, inflammation and NE hyperplasia. However, NTZ neither affected expression of SPEM markers nor of SPEM-related genes. In conclusion, NTZ prevented mucosal hypertrophy, cyst formation and NE cell hyperplasia but did not affect SPEM. The presence of SPEM seems unrelated to the changes caused by hypergastrinemia in this animal model.

A signalling cascade of IL-33 to IL-13 regulates metaplasia in the mouse stomach

OBJECTIVE

Alternatively activated macrophages (M2) are associated with the progression of spasmolytic polypeptide-expressing metaplasia (SPEM) in the stomach. However, the precise mechanism(s) and critical mediators that induce SPEM are unknown.

DESIGN

To determine candidate genes important in these processes, macrophages from the stomach corpus of mice with SPEM (DMP-777-treated) or advanced SPEM (L635-treated) were isolated and RNA sequenced. Effects on metaplasia development after acute parietal cell loss induced by L635 were evaluated in interleukin (IL)-33, IL-33 receptor (ST2) and IL-13 knockout (KO) mice.

RESULTS

Profiling of metaplasia-associated macrophages in the stomach identified an M2a-polarised macrophage population. Expression of IL-33 was significantly upregulated in macrophages associated with advanced SPEM. L635 induced metaplasia in the stomachs of wild-type mice, but not in the stomachs of IL-33 and ST2 KO mice. While IL-5 and IL-9 were not required for metaplasia induction, IL-13 KO mice did not develop metaplasia in response to L635. Administration of IL-13 to ST2 KO mice re-established the induction of metaplasia following acute parietal cell loss.

CONCLUSIONS

Metaplasia induction and macrophage polarisation after parietal cell loss is coordinated through a cytokine signalling network of IL-33 and IL-13, linking a combined response to injury by both intrinsic mucosal mechanisms and infiltrating M2 macrophages.

Murine Models of Gastric Corpus Preneoplasia

Intestinal-type gastric adenocarcinoma evolves in a field of pre-existing metaplasia. Over the past 20 years, a number of murine models have been developed to address aspects of the physiology and pathophysiology of metaplasia induction. Although none of these models has achieved true recapitulation of the induction of adenocarcinoma, they have led to important insights into the factors that influence the induction and progression of metaplasia. Here, we review the pathologic definitions relevant to alterations in gastric corpus lineages and classification of metaplasia by specific lineage markers. In addition, we review present murine models of the induction and progression of spasmolytic polypeptide (TFF2)-expressing metaplasia, the predominant metaplastic lineage observed in murine models. These models provide a basis for the development of a broader understanding of the physiological and pathophysiological roles of metaplasia in the stomach.

Identification of alanyl aminopeptidase (CD13) as a surface marker for isolation of mature gastric zymogenic chief cells

Injury and inflammation in the gastric epithelium can cause disruption of the pathways that guide the differentiation of cell lineages, which in turn can cause persistent alterations in differentiation patterns, known as metaplasia. Metaplasia that occurs in the stomach is associated with increased risk for cancer. Methods for isolating distinct gastric epithelial cell populations would facilitate dissection of the molecular and cellular pathways that guide normal and metaplastic differentiation. Here, we identify alanyl aminopeptidase (CD13) as a specific surface marker of zymogenic chief cells (ZCs) in the gastric epithelium. We show that 1) among gastric epithelial cells alanyl aminopeptidase expression is confined to mature ZCs, and 2) its expression is lost en route to metaplasia in both mouse and human stomachs. With this new marker coupled with new techniques that we introduce for dissociating gastric epithelial cells and overcoming their constitutive autofluorescence, we are able to reliably isolate enriched populations of ZCs for both molecular analysis and for the establishment of ZC-derived ex vivo gastroid cultures.

Mucosal expression of aquaporin-4 in the stomach of histamine type 2 receptor knockout mice and Helicobacter pylori-infected mice

BACKGROUND AND AIM

Basolateral water channel, aquaporin-4 (AQP4), is known to be expressed in gastric parietal cells, especially in the basal side of gastric mucosa. However, the role of AQP4 in the stomach is still unknown. Histamine type 2 receptor (H2R) knockout mice, which are characterized by suppressed gastric acid secretion, are known as formation of mucosal hyperplasia with cystic dilatation and spasmolytic polypeptide-expressing metaplasia (SPEM) in the stomach. The aim of the present study is to investigate whether the expression of AQP4 is changed by the condition of acid suppression and Helicobacter pylori infection.

METHODS

Male H2 R knockout mice and their controls (C57BL/6) were used. H. pylori was orally infected at the age of 5 weeks. The distributions of AQP4 and H+/K+-ATPase in the gastric mucosa were investigated by fluorescent immunohistochemistry. The mRNA expressions of AQP4, H+/K+-ATPase, sonic hedgehog (Shh), and trefoil factor-2 (TFF2) were investigated by quantitative reverse transcription polymerase chain reaction (RT-PCR).

RESULTS

In the H2 R knockout mice, the distribution of AQP4-positive parietal cells was extended toward the surface of the fundic glands. Although the mRNA expression levels of AQP4 and H+/K+ATPase were elevated in H2 R knockout mice at the age of 20 weeks, the elevations were not maintained by aging or H. pylori infection. In H2 R knockout mice with H. pylori infection, the expression level of TFF2 mRNA was elevated while the ratio between AQP4 and H+/K+ ATPase mRNA expression was decreased compared with the H2 R knockout mice without H. pylori infection.

CONCLUSIONS

In the H2 R knockout mice, massive SPEM was induced by H. pylori colonization and the ratio between AQP4 and H+/K+ATPase mRNA expression was decreased.

Cell lineage distribution atlas of the human stomach reveals heterogeneous gland populations in the gastric antrum

OBJECTIVE

The glands of the stomach body and antral mucosa contain a complex compendium of cell lineages. In lower mammals, the distribution of oxyntic glands and antral glands define the anatomical regions within the stomach. We examined in detail the distribution of the full range of cell lineages within the human stomach.

DESIGN

We determined the distribution of gastric gland cell lineages with specific immunocytochemical markers in entire stomach specimens from three non-obese organ donors.

RESULTS

The anatomical body and antrum of the human stomach were defined by the presence of ghrelin and gastrin cells, respectively. Concentrations of somatostatin cells were observed in the proximal stomach. Parietal cells were seen in all glands of the body of the stomach as well as in over 50% of antral glands. MIST1 expressing chief cells were predominantly observed in the body although individual glands of the antrum also showed MIST1 expressing chief cells. While classically described antral glands were observed with gastrin cells and deep antral mucous cells without any parietal cells, we also observed a substantial population of mixed type glands containing both parietal cells and G cells throughout the antrum.

CONCLUSIONS

Enteroendocrine cells show distinct patterns of localisation in the human stomach. The existence of antral glands with mixed cell lineages indicates that human antral glands may be functionally chimeric with glands assembled from multiple distinct stem cell populations.

Gastric secretion

PURPOSE OF REVIEW

This review summarizes the past year's literature regarding the regulation of gastric exocrine and endocrine secretion at the central, peripheral, and cellular levels.

RECENT FINDINGS

Gastric acid secretion is an intricate and dynamic process that is regulated by neural (efferent and afferent), hormonal (e.g., gastrin), and paracrine (e.g., histamine, ghrelin, somatostatin) pathways as well as mechanical (e.g., distension) and chemical (e.g., protein, glutamate, coffee, and ethanol) stimuli. Secretion of hydrochloric acid by the parietal cell involves recruitment and fusion of HK-adenosine triphosphatase (HK-ATPase)-containing cytoplasmic tubulovesicles with the apical membrane with subsequent electroneutral transport of hydronium ions in exchange for potassium; the source of the latter is the potassium channel, KCNQ1. Concomitantly, chloride exits via the cystic fibrosis transmembrane regulator. Inhibition of the HK-ATPase by proton pump inhibitors leads to a compensatory hypergastrinemia which, if prolonged, results in parietal and enterochromaffin-like cell hyperplasia. The clinical consequence is rebound acid secretion which may induce dyspeptic symptoms in healthy individuals and exacerbate reflux symptoms in patients with gastroesophageal reflux disease.

SUMMARY

We continue to make progress in our understanding of the regulation of gastric acid secretion in health and disease. A better understanding of the pathways and mechanisms regulating acid secretion should lead to improved management of patients with acid-induced disorders as well as those who secrete too little acid.