Gastric type I carcinoid: a pilot study with human G17DT immunogen vaccination

Low Pepsinogen I/II Ratio and High Gastrin-17 Levels Typify Chronic Atrophic Autoimmune Gastritis Patients With Gastric Neuroendocrine Tumors

Chronic atrophic autoimmune gastritis (CAAG) can lead to the development of gastric neuroendocrine tumors (gNETs) and can be accompanied by other autoimmune diseases. This study aimed to determine, in CAAG patients, the association of gNET development, the prevalence of autoimmune diseases other than CAAG, the association of autoimmunity, and gNET development with pepsinogen I, II, gastrin-17, and Helicobacter pylori infection analysis.

Immunogenicity and safety of a novel tetanus toxoid-conjugated anti-gastrin vaccine in BALB/c mice

The objective of this study is to determine the immunogenicity and safety of our novel anti-gastrin vaccine that is composed of the common amino-terminal portions of human carboxy-amidated gastrin-17 (G17) and glycine-extended gastrin-17 (gly-G17) as well as the common carboxy-terminal portion of the gastrin precursor progastrin (in a 50:50 mixture) all covalently linked to tetanus toxoid (TT) via peptide spacers. The vaccine, or immunogen, was injected intramuscularly into the legs of BALB/c mice, which produced high serum titres of specific IgG antibodies and IFN-γ in their spleen cells, identifiable by enzyme-linked immunosorbent assay (ELISA) and enzyme-linked immunospot assay (ELISPOT), respectively. TT as the protein carrier effectively enhanced the antigenic epitopes' humoural and cellular immune responses, unlike the antigenic epitopes alone or the immunogen's adjuvant emulsion system (AES), all of which failed to provoke any obvious immune response. Notably, the animals' body weights increased significantly after immunization (P < .01), while their haematology and serum biochemistry were all generally normal, and the gross anatomy of their main organs (e.g., heart, liver, spleen, lung, kidney) showed no obvious histopathological changes.

Gastric carcinoids (neuroendocrine neoplasms)

Gastric neuroendocrine neoplasms of the stomach can be divided into the usually well-differentiated, hypergastrinemia-dependent type I and II lesions and the more aggressively behaving gastrin-independent type III lesions. Studying menin and its complex interrelationship with gastrin may provide insight into tumor biology at the clinical level and in terms of basic cell biology (eg, the role of the epigenome in neuroendocrine cell proliferation), and lead to potential consideration of other targets that are known candidates for molecular-based therapies in other adenocarcinomas.

Gastrin receptor pharmacology

C-terminally amidated gastrins act at cholecystokinin-2 receptors (CCK2R), which are normally expressed by gastric parietal and enterochromaffin-like (ECL) cells and smooth muscle; there is also extensive expression in the CNS where the main endogenous ligand is cholecystokinin. A variety of neoplasms express CCK2R, or splice variants, including neuroendocrine, pancreatic, medullary thyroid and lung cancers. Other products of the gastrin gene (progastrin, the Gly-gastrins) may stimulate cell proliferation but are not CCK2R ligands. Depending on the cell type, stimulation of CCK2R evokes secretion, increases proliferation and cell migration, inhibits apoptosis, and controls the expression of various genes. These effects are mediated by increased intracellular calcium and activation of protein kinase C, MAPkinase and other protein kinase cascades. There has been recent progress in developing CCK2R ligands that can be used for imaging tumours expressing the receptor. New antagonists have also been developed, and there is scope for using these for suppression of gastric acid and for treatment of neuroendocrine and other CCK2R-expressing tumours.

Management of gastric carcinoids (neuroendocrine neoplasms)

Gastric neuroendocrine neoplasms of the stomach can be divided into the usually well-differentiated, hypergastrinemia-dependent type I and II lesions and the more aggressively behaving gastrin-independent type III lesions. Mainly due to better diagnostics and awareness of this tumor, the observed incidence has increased more than tenfold over the last 30 years. Small (<15-20 mm) localized type I and II lesions that are slowly proliferating (Ki67<2%) can usually be managed conservatively with endoscopic surveillance. Reducing hypergastrinemia by surgical removal of an underlying gastrinoma is important in inhibiting growth and induce reduction of type II lesions, while the specific gastrin receptor antagonist YF476 or gastrin antibodies may become useful for both type I and II lesions. Infiltrating and metastasized tumors and type III lesions require a more aggressive approach with surgical resection and consideration of modalities such as somatostatin analogs, cytotoxics, and peptide receptor targeted treatment.

Autoimmune gastritis: histology phenotype and OLGA staging

BACKGROUND

Among Western populations, the declining incidence of Helicobacter pylori infection coincides with a growing clinical impact of autoimmune gastritis.

AIMS

To describe the histological phenotype of autoimmune gastritis, also to test the prognostic impact of OLGA staging in the autoimmune setting.

METHODS

A single-institutional series (spanning the years 2003-2011) of 562 consecutive patients (M:F ratio: 1:3.7; mean age = 57.6 ± 14.4 years) with serologically confirmed autoimmune gastritis underwent histology review and OLGA staging.

RESULTS

Helicobacter pylori infection was ascertained histologically in 44/562 cases (7.8%). Forty six biopsy sets (8.2%) featured OLGA stages III-IV; they included all four cases of incidental epithelial neoplasia (three intraepithelial and one invasive; three of these four cases had concomitant H. pylori infection). There were 230 (40.9%) and 139 (24.7%) cases, respectively, of linear and micro-nodular enterochromaffin-like cell hyperplasia; 19 (3.4%) type I carcinoids were detected. The series included 116 patients who underwent repeated endoscopy/biopsy sampling (mean time elapsing between the two procedures = 54 months; range 24-108). Paired histology showed a significant (P = 0.009) trend towards a stage progression [the stage increased in 25/116 cases (22%); it remained unchanged in 87/116 cases (75%)].

CONCLUSIONS

In autoimmune gastritis, the cancer risk is restricted to high-risk gastritis stages (III-IV), and is associated mainly with concomitant H. pylori infection. OLGA staging consistently depicts the time-dependent organic progression of the autoimmune disease and provides key information for secondary gastric cancer prevention strategies.