Primer: histopathology for the clinician—how to interpret biopsy information for gastritis

Metagenomic and single-cell RNA-Seq survey of the Helicobacter pylori-infected stomach in asymptomatic individuals

Helicobacter pylori colonization of the gastric niche can persist for years in asymptomatic individuals. To deeply characterize the host-microbiota environment in H. pylori-infected (HPI) stomachs, we collected human gastric tissues and performed metagenomic sequencing, single-cell RNA-Seq (scRNA-Seq), flow cytometry, and fluorescent microscopy. HPI asymptomatic individuals had dramatic changes in the composition of gastric microbiome and immune cells compared with noninfected individuals. Metagenomic analysis uncovered pathway alterations related to metabolism and immune response. scRNA-Seq and flow cytometry data revealed that, in contrast to murine stomachs, ILC2s are virtually absent in the human gastric mucosa, whereas ILC3s are the dominant population. Specifically, proportion of NKp44+ ILC3s out of total ILCs were highly increased in the gastric mucosa of asymptomatic HPI individuals, and correlated with the abundance of selected microbial taxa. In addition, CD11c+ myeloid cells and activated CD4+ T cells and B cells were expanded in HPI individuals. B cells of HPI individuals acquired an activated phenotype and progressed into a highly proliferating germinal-center stage and plasmablast maturation, which correlated with the presence of tertiary lymphoid structures within the gastric lamina propria. Our study provides a comprehensive atlas of the gastric mucosa-associated microbiome and immune cell landscape when comparing asymptomatic HPI and uninfected individuals.

Plasmonic Alloys Reveal a Distinct Metabolic Phenotype of Early Gastric Cancer

Gastric cancer (GC) is a multifactorial process, accompanied by alterations in metabolic pathways. Non-invasive metabolic profiling facilitates GC diagnosis at early stage leading to an improved prognostic outcome. Herein, mesoporous PdPtAu alloys are designed to characterize the metabolic profiles in human blood. The elemental composition is optimized with heterogeneous surface plasmonic resonance, offering preferred charge transfer for photoinduced desorption/ionization and enhanced photothermal conversion for thermally driven desorption. The surface structure of PdPtAu is further tuned with controlled mesopores, accommodating metabolites only, rather than large interfering compounds. Consequently, the optimized PdPtAu alloy yields direct metabolic fingerprints by laser desorption/ionization mass spectrometry in seconds, consuming 500 nL of native plasma. A distinct metabolic phenotype is revealed for early GC by sparse learning, resulting in precise GC diagnosis with an area under the curve of 0.942. It is envisioned that the plasmonic alloy will open up a new era of minimally invasive blood analysis to improve the surveillance of cancer patients in the clinical setting.

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.

Mid- and Deep-Zone Gastritis: A Histologic Pattern Associated With Autoimmune Disease but Distinct From Autoimmune Atrophic Gastritis

OBJECTIVES

We sought to characterize a histologic pattern of mid- and deep-zone gastritis, distinct from the typical pattern of Helicobacter pylori or autoimmune gastritis and to see if it had any clinicopathologic association(s).

METHODS

We analyzed inflammatory patterns and composition, excluded autoimmune gastritis using immunohistochemistry, and reviewed the medical record for demographics, medical/surgical history, presenting symptoms, endoscopic findings, and medications for 28 cases.

RESULTS

All cases had inflammation in the middle and/or deep mucosal zones with sparing of the superficial/pit compartment. Subfeatures included corpus or antral predominance, pangastric involvement, prominence of a subset(s) of inflammatory cells, and degree of epithelial injury. Of 28 patients, 13 had autoimmune disease(s), autoantibodies, or both. There was no other unifying clinical feature.

CONCLUSIONS

This unique pattern of gastritis should be distinguished from other entities such as H pylori and autoimmune gastritis. At least a subset may be an autoimmune condition different from classic autoimmune gastritis.

Johns Hopkins course: 8th annual Current Topics in Gastrointestinal and Liver Pathology

The 8th annual Current Topics in Gastrointestinal and Liver Pathology course was held on the campus of the Johns Hopkins Medical Institutions in Baltimore, MD, USA, on the 8-9 November 2008. Lectures and hands-on microscopy sessions were provided by the Johns Hopkins Division of Gastrointestinal Pathology faculty and a guest faculty member from the University of Michigan (MI, USA). Key topics included newly recognized staging issues, the application of molecular techniques and practical topics for diagnostic pathologists.

Practical approach to the pathologic diagnosis of gastritis

CONTEXT

Most types of gastritis can be diagnosed on hematoxylin-eosin stains. The most common type of chronic gastritis is Helicobacter pylori gastritis. Reactive or chemical gastropathy, which is often associated with nonsteroidal anti-inflammatory drug use or bile reflux, is common in most practices. The diagnosis of atrophic gastritis can be challenging if few biopsy samples are available and if the location of the biopsies in the stomach is not known, such as when random biopsies are sampled in one jar. If the biopsy site is not known, immunohistochemical stains, such as a combination of synaptophysin and gastrin, are useful in establishing the biopsy location.

OBJECTIVE

To demonstrate a practical approach to achieving a pathologic diagnosis of gastritis by evaluating a limited number of features in mucosal biopsies.

DATA SOURCE

In this article, we present several representative gastric biopsy cases from a gastrointestinal pathology practice to demonstrate the practical application of basic histopathologic methods for the diagnosis of gastritis.

CONCLUSIONS

Limited ancillary tests are usually required for a diagnosis of gastritis. In some cases, special stains, such as acid-fast stains, and immunohistochemical stains, such as for H pylori and viruses, can be useful. Helicobacter pylori immunohistochemical stains can particularly contribute (1) when moderate to severe, chronic gastritis or active gastritis is present but no Helicobacter organisms are identified upon hematoxylin-eosin stain; (2) when extensive intestinal metaplasia is present; and (3) in follow-up biopsies, after antibiotic treatment for H pylori.