Host response genes associated with nodular gastritis in Helicobacter pylori infection

Histopathological staging and differential diagnosis of marginal zone lymphoma of gastric mucosa-associated lymphoid tissue

The purpose of this study was to explore the histopathological staging and differential diagnosis of marginal zone lymphoma in gastric mucosa-associated lymphoid tissue (MALT lymphoma). We performed detailed histomorphology and immunohistochemistry investigations as well as genetic testing on endoscopic biopsy and endoscopic mucosal resection specimens from 18 patients with gastric MALT lymphoma. We found that gastric MALT lymphoma typically begins as a small, isolated area outside the lymphoid follicular mantle zone or proliferates in a multifocal, patchy manner, gradually spreads to the interfollicular zone, forming diffuse proliferation, invades the gastric mucosal glands, and infiltrates or proliferates into the center of peripheral reactive lymphoid follicles. Abnormally proliferating lymphocytes invade the surrounding lymphoid follicles, resulting in damage, atrophy, and disappearance of their normal follicles as well as of the gastric mucosa glands, forming diffuse proliferation. Redifferentiation and proliferation lead to the transformation of lymphocytes; that is, MALT transitions into highly invasive lymphoma. Based on our findings in this study, we propose the following five stages in the process of development and progression of gastric MALT lymphoma: the stage of cell proliferation outside the lymphoid follicular mantle zone; the stage of heterogeneous proliferative lymphoepithelial lesion; the stage of reactive lymphoid follicular implantation; the stage of lymphoid follicular clonal proliferation; and the stage of MALT transforming into highly invasive lymphoma. We examined the differential diagnosis of histopathological features at each stage. The clinicopathological staging of gastric MALT lymphoma can help clinicians provide accurate treatment and track malignant cell transformation, thus playing a significant role in controlling its development and progression.

Severe induction of aberrant DNA methylation by nodular gastritis in adults

BACKGROUND

Nodular gastritis (NG) is characterized by marked antral lymphoid follicle formation, and is a strong risk factor for diffuse-type gastric cancer in adults. However, it is unknown whether aberrant DNA methylation, which is induced by atrophic gastritis (AG) and is a risk for gastric cancer, is induced by NG. Here, we analyzed methylation induction by NG.

METHODS

Gastric mucosal samples were obtained from non-cancerous antral tissues of 16 NG and 20 AG patients with gastric cancer and 5 NG and 6 AG patients without, all age- and gender-matched. Genome-wide methylation analysis and expression analysis were conducted by a BeadChip array and RNA-sequencing, respectively.

RESULTS

Clustering analysis of non-cancerous antral tissues of NG and AG patients with gastric cancer was conducted using methylation levels of 585 promoter CpG islands (CGIs) of methylation-resistant genes, and a large fraction of NG samples formed a cluster with strong methylation induction. Promoter CGIs of CDH1 and DAPK1 tumor-suppressor genes were more methylated in NG than in AG. Notably, methylation levels of these genes were also higher in the antrum of NG patients without cancer. Genes related to lymphoid follicle formation, such as CXCL13/CXCR5 and CXCL12/CXCR4, had higher expression in NG, and genes involved in DNA demethylation TET2 and IDH1, had only half the expression in NG.

CONCLUSIONS

Severe aberrant methylation, involving multiple tumor-suppressor genes, was induced in the gastric antrum and body of patients with NG, in accordance with their high gastric cancer risk.

Translation of gastric disease progression at gene level expression

Helicobacter pylori is associated with the development of several lesions in the human stomach. This chronic infection produces gastritis, which can progress to intestinal metaplasia and gastric cancer. To date, there is very little information regarding gene-expression in the different phases of progression caused by chronic H. pylori infection. In this study, we performed a genome-wide gene-expression analysis in gastric biopsies of patients chronically infected with H. pylori, using the potential of high-throughput technologies that have not been fully exploited in this area. Here we illustrate the potential correlation of H. pylori infection with the gene expression changes in follicular gastritis, chronic gastritis and intestinal metaplasia. We also suggest its potential as biomarkers of each condition. An exploratory set of 21 biopsies from patients with follicular gastritis, chronic gastritis, and intestinal metaplasia were analyzed by gene-expression microarrays in order to identify the biological processes altered in each lesion. The microarray data was corroborated by real-time PCR, while 79 Formalin-Fixed Paraffin-Embeded samples were analyzed by immunohistochemistry. Follicular gastritis exhibited significant enrichment in genes associated with glutamate signaling, while chronic gastritis showed a down-regulation in metallothionein 1 and 2 and in oxidative phosphorylation-related genes, which could be associated with the chronic infecton of H. pylori. Intestinal metaplasia exhibited an over-expression of gastrointestinal stem cell markers, such as LGR5 and PROM1, as well as messenger RNA and nucleic acid metabolism-related genes. The gene-expression patterns found in this study provide new comparative information about chronic gastritis, follicular gastritis and intestinal metaplasia that may play an important role in the development of gastric cancer.

Helicobacter pylori and some aspects of gut microbiota in children

Helicobacter pylori infection in children differs from infection in adults in many aspects. The rate of infection, epidemiology, clinical presentations and complications, the applicability of diagnostic tests, antibiotic resistance, treatment options, and success rates differ significantly. Due to all these differences, management guidelines for children and adults differ also substantially. In 2017, the Updated ESPGHAN and NASPGHAN Guidelines on the management of H. pylori infection in children were published, emphasizing the differences in clinical presentation and indications for treatment, stating that the primary goal of clinical investigation in children is to identify the cause of upper gastrointestinal symptoms rather than the presence of H. pylori infection. Therefore, the diagnosis should be based on upper endoscopy, and the "test and treat strategy" should not be used in children. Due to an increasing rate of antibiotic resistance worldwide, the updated guidelines recommend broader use of antimicrobial susceptibility testing for H. pylori strains in order to tailor eradication treatment accordingly. Moreover, treatment in children should be prescribed only when indicated and should be based on the rate of eradication in local populations aiming for treatment success above 90%. During the last two decades there has been a steady decrease in the rate of H. pylori infection in both children and adults in the Western world. Two recent publications studying the incidence of H. pylori infection confirmed that early childhood is a time for acquisition of infection both in industrialized and nonindustrialized countries. In addition, they showed that H. pylori could be acquired outside the family. In respect to the inverse association between H. pylori and allergy, a longitudinal study demonstrated that early exposure to H. pylori at any age was inversely associated with atopy and allergic conditions.