Hexane Extracts of Calophyllum brasiliense Inhibit the Development of Gastric Preneoplasia in Helicobacter felis Infected INS-Gas Mice

Brasiliensic acid: in vitro cytotoxic and genotoxic, in vivo acute toxicity and in silico pharmacological prediction of a new promising molecule

Brasiliensic acid (Bras) is a chromanone isolated from Calophyllum brasiliense Cambèss. bark extracts with confirmed potential activity on gastric ulcer and Helicobacter pylori infection. This study aimed to investigate the in vitro and in vivo toxicity of Bras and molecular docking studies on its interactions with the H. pylori virulence factors and selected gastric cancer-related proteins. Cytotoxicity was evaluated by alamarBlue© assay, genotoxicity by micronucleus and comet assays, and on cell cycle by flow cytometry, using Chinese hamster epithelial ovary cells. Bras was not cytotoxic to CHO-K1 cells, and caused no chromosomal aberrations, nor altered DNA integrity. Furthermore, Bras inhibited damages to DNA by H2O2 at 1.16 µM. No cell cycle arrest was observed, but apoptosis accounted for 31.2% of the cell death observed in the CHO-K1 at 24 h incubation of the IC50. Oral acute toxicity by Hippocratic screening test in mice showed no relevant behavioral change/mortality seen up to 1,000 mg/kg. The molecular docking approach indicated potential interactions between Bras and the various targets for peptic ulcer and gastric cancer, notably CagA virulence factor of H. pylori and VEGFR-2. In conclusion, Bras is apparently safe and an optimization for Bras can be considered for gastric ulcer and cancer.Communicated by Ramaswamy H. Sarma.

Gastric Helicobacter species associated with dogs, cats and pigs: significance for public and animal health

This article focuses on the pathogenic significance of Helicobacter species naturally colonizing the stomach of dogs, cats and pigs. These gastric "non-Helicobacter (H.) pylori Helicobacter species" (NHPH) are less well-known than the human adapted H. pylori. Helicobacter suis has been associated with gastritis and decreased daily weight gain in pigs. Several studies also attribute a role to this pathogen in the development of hyperkeratosis and ulceration of the non-glandular stratified squamous epithelium of the pars oesophagea of the porcine stomach. The stomach of dogs and cats can be colonized by several Helicobacter species but their pathogenic significance for these animals is probably low. Helicobacter suis as well as several canine and feline gastric Helicobacter species may also infect humans, resulting in gastritis, peptic and duodenal ulcers, and low-grade mucosa-associated lymphoid tissue lymphoma. These agents may be transmitted to humans most likely through direct or indirect contact with dogs, cats and pigs. Additional possible transmission routes include consumption of water and, for H. suis, also consumption of contaminated pork. It has been described that standard H. pylori eradication therapy is usually also effective to eradicate the NHPH in human patients, although acquired antimicrobial resistance may occasionally occur and porcine H. suis strains are intrinsically less susceptible to aminopenicillins than non-human primate H. suis strains and other gastric Helicobacter species. Virulence factors of H. suis and the canine and feline gastric Helicobacter species include urease activity, motility, chemotaxis, adhesins and gamma-glutamyl transpeptidase. These NHPH, however, lack orthologs of cytotoxin-associated gene pathogenicity island and vacuolating cytotoxin A, which are major virulence factors in H. pylori. It can be concluded that besides H. pylori, gastric Helicobacter species associated with dogs, cats and pigs are also clinically relevant in humans. Although recent research has provided better insights regarding pathogenic mechanisms and treatment strategies, a lot remains to be investigated, including true prevalence rates, exact modes of transmission and molecular pathways underlying disease development and progression.

Helicobacter pylori antibiotic eradication coupled with a chemically defined diet in INS-GAS mice triggers dysbiosis and vitamin K deficiency resulting in gastric hemorrhage

Infection with Helicobacter pylori causes chronic inflammation and is a risk factor for gastric cancer. Antibiotic treatment or increased dietary folate prevents gastric carcinogenesis in male INS-GAS mice. To determine potential synergistic effects, H. pylori-infected male INS-GAS mice were fed an amino acid defined (AAD) diet with increased folate and were treated with antibiotics after 18 weeks of H. pylori infection. Antibiotic therapy decreased gastric pathology, but dietary folate had no effect. However, the combination of antibiotics and the AAD diet induced anemia, gastric hemorrhage, and mortality. Clinical presentation suggested hypovitaminosis K potentially caused by dietary deficiency and dysbiosis. Based on current dietary guidelines, the AAD diet was deficient in vitamin K. Phylloquinone administered subcutaneously and via a reformulated diet led to clinical improvement with no subsequent mortalities and increased hepatic vitamin K levels. We characterized the microbiome and menaquinone profiles of antibiotic-treated and antibiotic-free mice. Antibiotic treatment decreased the abundance of menaquinone producers within orders Bacteroidales and Verrucomicrobiales. PICRUSt predicted decreases in canonical menaquinone biosynthesis genes, menA and menD. Reduction of menA from Akkermansia muciniphila, Bacteroides uniformis, and Muribaculum intestinale were confirmed in antibiotic-treated mice. The fecal menaquinone profile of antibiotic-treated mice had reduced MK5 and MK6 and increased MK7 and MK11 compared to antibiotic-free mice. Loss of menaquinone-producing microbes due to antibiotics altered the enteric production of vitamin K. This study highlights the role of diet and the microbiome in maintaining vitamin K homeostasis.

Netazepide Inhibits Expression of Pappalysin 2 in Type 1 Gastric Neuroendocrine Tumors

BACKGROUND & AIMS

In patients with autoimmune atrophic gastritis and achlorhydria, hypergastrinemia is associated with the development of type 1 gastric neuroendocrine tumors (gNETs). Twelve months of treatment with netazepide (YF476), an antagonist of the cholecystokinin B receptor (CCKBR or CCK2R), eradicated some type 1 gNETs in patients. We investigated the mechanisms by which netazepide induced gNET regression using gene expression profiling.

METHODS

We obtained serum samples and gastric corpus biopsy specimens from 8 patients with hypergastrinemia and type 1 gNETs enrolled in a phase 2 trial of netazepide. Control samples were obtained from 10 patients without gastric cancer. We used amplified and biotinylated sense-strand DNA targets from total RNA and Affymetrix (Thermofisher Scientific, UK) Human Gene 2.0 ST microarrays to identify differentially expressed genes in stomach tissues from patients with type 1 gNETs before, during, and after netazepide treatment. Findings were validated in a human AGSGR gastric adenocarcinoma cell line that stably expresses human CCK2R, primary mouse gastroids, transgenic hypergastrinemic INS-GAS mice, and patient samples.

RESULTS

Levels of pappalysin 2 (PAPPA2) messenger RNA were reduced significantly in gNET tissues from patients receiving netazepide therapy compared with tissues collected before therapy. PAPPA2 is a metalloproteinase that increases the bioavailability of insulin-like growth factor (IGF) by cleaving IGF binding proteins (IGFBPs). PAPPA2 expression was increased in the gastric corpus of patients with type 1 gNETs, and immunohistochemistry showed localization in the same vicinity as CCK2R-expressing enterochromaffin-like cells. Up-regulation of PAPPA2 also was found in the stomachs of INS-GAS mice. Gastrin increased PAPPA2 expression with time and in a dose-dependent manner in gastric AGSGR cells and mouse gastroids by activating CCK2R. Knockdown of PAPPA2 in AGSGR cells with small interfering RNAs significantly decreased their migratory response and tissue remodeling in response to gastrin. Gastrin altered the expression and cleavage of IGFBP3 and IGFBP5.

CONCLUSIONS

In an analysis of human gNETS and mice, we found that gastrin up-regulates the expression of gastric PAPPA2. Increased PAPPA2 alters IGF bioavailability, cell migration, and tissue remodeling, which are involved in type 1 gNET development. These effects are inhibited by netazepide.

Other Helicobacters, gastric and gut microbiota

The current article is a review of the most important and relevant literature published in 2016 and early 2017 on non-Helicobacter pylori Helicobacter infections in humans and animals, as well as interactions between H. pylori and the microbiota of the stomach and other organs. Some putative new Helicobacter species were identified in sea otters, wild boars, dogs, and mice. Many cases of Helicobacter fennelliae and Helicobacter cinaedi infection have been reported in humans, mostly in immunocompromised patients. Mouse models have been used frequently as a model to investigate human Helicobacter infection, although some studies have investigated the pathogenesis of Helicobacters in their natural host, as was the case for Helicobacter suis infection in pigs. Our understanding of both the gastric and gut microbiome has made progress and, in addition, interactions between H. pylori and the microbiome were demonstrated to go beyond the stomach. Some new approaches of preventing Helicobacter infection or its related pathologies were investigated and, in this respect, the probiotic properties of Saccharomyces, Lactobacillus and Bifidobacterium spp. were confirmed.