Morphological and pathologic changes of experimental chronic atrophic gastritis (CAG) and the regulating mechanism of protein expression in rats

Alteration of gastric microbiota and transcriptome in a rat with gastric intestinal metaplasia induced by deoxycholic acid

Objective

Bile reflux plays a key role in the development of gastric intestinal metaplasia (GIM), an independent risk factor of gastric cancer. Here, we aimed to explore the biological mechanism of GIM induced by bile reflux in a rat model.

Methods

Rats were treated with 2% sodium salicylate and allowed to freely drink 20 mmol/L sodium deoxycholate for 12 weeks, and GIM was confirmed by histopathological analysis. Gastric microbiota was profiled according to the 16S rDNA V3-V4 region, gastric transcriptome was sequenced, and serum bile acids (BAs) were analyzed by targeted metabolomics. Spearman's correlation analysis was used in constructing the network among gastric microbiota, serum BAs, and gene profiles. Real-time polymerase chain reaction (RT-PCR) measured the expression levels of nine genes in the gastric transcriptome.

Results

In the stomach, deoxycholic acid (DCA) decreased the microbial diversity but promoted the abundances of several bacterial genera, such as Limosilactobacillus, Burkholderia-Caballeronia-Paraburkholderia, and Rikenellaceae RC9 gut group. Gastric transcriptome showed that the genes enriched in gastric acid secretion were significantly downregulated, whereas the genes enriched in fat digestion and absorption were obviously upregulated in GIM rats. The GIM rats had four promoted serum BAs, namely cholic acid (CA), DCA, taurocholic acid, and taurodeoxycholic acid. Further correlation analysis showed that the Rikenellaceae RC9 gut group was significantly positively correlated with DCA and RGD1311575 (capping protein-inhibiting regulator of actin dynamics), and RGD1311575 was positively correlated with Fabp1 (fatty acid-binding protein, liver), a key gene involved in fat digestion and absorption. Finally, the upregulated expression of Dgat1 (diacylglycerol acyltransferase 1) and Fabp1 related to fat digestion and absorption was identified by RT-PCR and IHC.

Conclusion

DCA-induced GIM enhanced gastric fat digestion and absorption function and impaired gastric acid secretion function. The DCA-Rikenellaceae RC9 gut group-RGD1311575/Fabp1 axis might play a key role in the mechanism of bile reflux-related GIM.

Network pharmacology-based strategy to investigate pharmacological mechanisms of Zuojinwan for treatment of gastritis

BACKGROUND

Zuojinwan (ZJW), a classic herbal formula, has been extensively used to treat gastric symptoms in clinical practice in China for centuries. However, the pharmacological mechanisms of ZJW still remain vague to date.

METHODS

In the present work, a network pharmacology-based strategy was proposed to elucidate its underlying multi-component, multi-target, and multi-pathway mode of action against gastritis. First we collected putative targets of ZJW based on TCMSP and STITCH databases, and a network containing the interactions between the putative targets of ZJW and known therapeutic targets of gastritis was built. Then four topological parameters, "degree", "betweenness", "closeness", and "coreness" were calculated to identify the major targets in the network. Furthermore, the major hubs were imported to the Metacore database to perform a pathway enrichment analysis.

RESULTS

A total of 118 nodes including 59 putative targets of ZJW were picked out as major hubs in terms of their topological importance. The results of pathway enrichment analysis indicated that putative targets of ZJW mostly participated in various pathways associated with anti-inflammation response, growth and development promotion and G-protein-coupled receptor signaling. More importantly, five putative targets of ZJW (EGFR, IL-6, IL-1β, TNF-α and MCP-1) and two known therapeutic targets of gastritis (CCKBR and IL-12β) and a link target NF-κB were recognized as active factors involved in the main biological functions of treatment, implying the underlying mechanisms of ZJW acting on gastritis.

CONCLUSION

ZJW could alleviate gastritis through the molecular mechanisms predicted by network pharmacology, and this research demonstrates that the network pharmacology approach can be an effective tool to reveal the mechanisms of traditional Chinese medicine (TCM) from a holistic perspective.

Epidermal growth factor and prostaglandin E2 levels in Helicobacter pylori-positive gastric intraepithelial neoplasia

OBJECTIVE

To investigate levels of epidermal growth factor (EGF) and prostaglandin E2 (PGE2) in Han Chinese patients with Helicobacter pylori-positive gastric low-grade intraepithelial neoplasia (LGIN).

METHODS

In this prospective, observational study, gastric specimens from patients with LGIN were collected by gastroscopy with consecutive biopsy. EGF and PGE2 concentrations in serum and gastric juice from patients with LGIN were measured by enzyme-linked immunosorbent assay. Presence of H. pylori infection was assessed in patients with LGIN and healthy controls.

RESULTS

Out of 5 638 patients and 548 controls, H. pylori infection in patients with chronic gastritis was associated with disease type (endoscopic classification) and disease severity. Patients with H. pylori-positive LGIN had significantly higher concentrations of serum EGF and lower concentrations of serum PGE2 versus patients with H. pylori-negative LGIN. Serum EGF and PGE2 levels in patients with LGIN were not significantly associated with disease type, but were significantly associated with disease severity.

CONCLUSIONS

H. pylori infection was associated with chronic gastritis type (endoscopic classification) and disease severity. Abnormal EGF and PGE2 levels may be associated with H. pylori-positive LGIN in Han Chinese patients in central China.

Genetic and molecular aspects of Helicobacter pylori in gastritis, pre- cancerous conditions and gastric adenocrcinoma

Gastric adenocarcinoma is one of the most common malignancies worldwide. Many ethological causes have been introduced among which helicobacter pylori, as a gram-negative bacterium has been considered as an important pathological facilitating factor. This agent is also associated with different digestive diseases, such as gastritis, peptic ulcer, and mucosa-associated lymphoid tissue lymphoma. Recently, scientists have been described some molecular aspects that show the role of some apoptotic genes and proteins; for example: P53, Bcl2, C-Myc and Rb-suppressor systems in the H. pylori pathogenesis. Also the relationship between nitric oxide (NOSi genotype) with H. pylori infection has been shown. The aim of this mini-review is to explain better these genetically aspects of H.pylori pathogenesis.

Advances in development of animal models of chronic atrophic gastritis

Chronic atrophic gastritis (CAG) is a precancerous disease whose research and treatment has attracted much attention. Development of animal models of CAG is very important for the research of this disease. Wistar rats and SD rats are mainly experimental animals used for modeling; however, the age and sex of these animals differ among different studies, although many scholars believe that these factors might affect experimental results. Helicobacter pylori is a common risk factor for CAG and can be used to create CAG model successfully, but this method is time-consuming and the induced pathological changes are not stable. N-methyl-N'-nitro-N-nitrosoguanidine, ammonia, sodium deoxycholate, and sodium salicylate are currently commonly used substances for inducing CAG. These substances can be used either alone or in combination to induce CAG successfully; however, the consistent dosage and perfusion time standards have not been established. In addition, combination of disease and syndrome by traditional Chinese medicine can also be used to model CAG. This article reviews recent advances in the development of animal models of CAG.

The regenerating gene iα is overexpressed in atrophic gastritis rats with hypergastrinemia

The role of gastrin on the development of atrophic gastritis (AG) and its relationship with the expression of RegIα  in vivo remain unclear. We established experimental AG in rats by combination administration with sodium salicylate, alcohol, and deoxycholate sodium. The mean score of inflammation in gastric antrum in AG rats was significantly elevated (P < 0.05), while the number of glands dramatically decreased (P < 0.05). In addition, the cell proliferation in gastric glands was increased in experimental AG rats, as determined by immunohistochemistry staining of PCNA and GS II. The level of serum gastrin in AG rats was significantly elevated relative to that of normal rats (P < 0.01). Moreover, the expression of RegIα protein and its receptor mRNA was increased in gastric tissues in AG rats (P < 0.05). Taken together, we demonstrated that the overexpression of Reglα is related with hypergastrinemia in AG rats.

Development of a rat model of atrophic gastritis by implantation of a spring into the pylorus in combination with intragastric administration of hot salty starch paste

AIM: To establish a novel rat model of atrophic gastritis according to the characteristics of the disease in Chinese patients.

METHODS: Fifty-one healthy male Wistar rats were randomized into five groups: control group (n = 10), sham operation group (n = 10), 2-mo model group (n = 10), 3-mo model group (n = 10), and 4-mo model group (n = 11). Atrophic gastritis was induced in rats of the three model groups by implanting a spring into the pylorus and intragastrically administering hot salty starch paste. The control group did not underwent any operation and was treated with saline twice a week, i.g., for 4 wk, while the sham operation group underwent the same operation as model rats except for spring implantation and was treated with saline for the same duration. Serum levels of PGE2 and gastrin were measured by radioimmunoassay. Pathological assessment of gastric changes was performed after intragastric administration.

RESULTS: Serum levels of PGE2 and gastrin in the 4-mo model group were lower than those in the control and sham operation groups (all P < 0.05 or 0.01). All the rats of the model groups had histological manifestations in gastric mucosa mimicking atrophic gastritis. These pathological changes deteriorated in a time-dependent manner. The 4-mo model group had the highest constituent ratio of gastric mucosal volume (relative to the control group), followed by the 3- and 2-mo model groups and sham operation group (20.44%, 17.28%, 9.82 %, 3.30 %). The 4-mo model group also had the highest potency unit of gastric mucosa volume, followed by the 3- and 2-mo model groups, sham operation group and control group (1.000, 0.868, 0.527, 0.1884, 0.000). Time-response curve equation of gastric mucosa atrophy potency (Y, volume change relative percentage) and logarithmic time required to induce model (X, h) was Y = 0.1882+0.9108/[1+10^{(11.828001-3.709X)}] (R = 0.9992), and half atrophy time was 1 545 h (95% CI: 618.4 h -3 858 h) (approximately 2 mo).

CONCLUSION: A rat model of atrophic gastritis was successfully established by implanting a spring into the pylorus and intragastrically administering hot salty starch paste.

G cells and gastrin in chronic alcohol-treated rats

Numerous reports have described gastric mucosal injury in rats treated with high ethanol concentrations. However, to the best of our knowledge, ultrastructural characteristics of G cells and antral gastrin levels have not been previously reported, either in rats that chronically consumed alcohol or in human alcoholics. The goal of this study was to examine the effect of ethanol consumption (8.5 g/kg) over a 4-month period, under controlled nutritional conditions, on antral and plasma levels of gastrin, ultrastructure of G cells, morphometric characteristics of G cells by stereological methods, and analysis of endocrine cells in the gastric mucosa by immunohistochemistry. The chronic alcohol consumption resulted in a nonsignificant decrease in gastrin plasma levels and unchanged antral gastrin concentrations. A slightly damaged glandular portion of the gastric mucosa and dilatation of small blood vessels detected by histological analysis, suggests that ethanol has a toxic effect on the mucosal surface. Chronic alcohol treatment significantly decreased the number of antral G cells per unit area, and increased their cellular, nuclear, and cytoplasmatic profile areas. In addition, the volume density and diameter of G-cell granules, predominantly the pale and lucent types, were increased, indicating inhibition of gastrin release. Ethanol treatment also decreased the number of gastric somatostatin-, serotonin-, and histamine-immunoreactive cells, except the somatostatin cells in the pyloric mucosa, as well as both G: D: enterochromaffin cells (EC) cell ratios in the antrum and D: ECL cell ratios in the fundus. These results indicate that the change of morphometric parameters in G cells may be related to cellular dysfunction. Our findings also suggest that regulation of G-cell secretion was not mediated by locally produced somatostatin in ethanol-consuming rats, but may involve gastric luminal content and/or neurotransmitters of gastric nerve fibers.