Experimental Helicobacter pylori infection in association with other bacteria

The Protective Effect of Polysaccharide SAFP from Sarcodon aspratus on Water Immersion and Restraint Stress-Induced Gastric Ulcer and Modulatory Effects on Gut Microbiota Dysbiosis

Sarcodon aspratus is a popular edible fungus for its tasty flavour and can be used as a dietary supplement for its functional substances. This study was conducted to evaluate the potential health benefits of Sarcodon aspratus polysaccharides (SAFP) on water immersion and restraint stress (WIRS)-induced gastric ulcer in rats. The results indicated that SAFP could decrease myeloperoxidase (MPO) activity and plasma corticosterone levels, as well as enhance Prostaglandin E2 (PGE2) and Nitrate/nitrite (NOx) concentration in rats. Furthermore, SAFP significantly attenuated the stress damage, inflammation, pathological changes and gastric mucosal lesion in rats. Moreover, high-throughput pyrosequencing of 16S rRNA suggested that SAFP modulated the dysbiosis of gut microbiota by enhancing the relative abundance of probiotics, decreasing WIRS-triggered bacteria proliferation. In summary, these results provided the evidence that SAFP exerted a beneficial effect on a WIRS-induced gastric ulcer via blocking the TLR4 signaling pathway and activating the Nrf2 signaling pathway. Notably, SAFP could modulate the WIRS-induced dysbiosis of gut microbiota. Thus, SAFP might be explored as a natural gastric mucosal protective agent in the prevention of gastric ulcers and other related diseases in the food and pharmaceutical industries.

Intestinal microbial patterns of the common marmoset and rhesus macaque

The intestinal microflora of common marmosets and rhesus monkeys were compared by enumerating bacteria from the small and large intestines. Rhesus monkeys had a consistent microflora pattern manifest by higher concentrations of total and Gram-negative aerobic and facultatively anaerobic bacteria, as well as aerobic and anaerobic Lactobacilli, in the large intestine as compared to the small intestine. In contrast, the marmoset microflora were considerably more variable. Approximately two-thirds of the marmosets (designated group A) had an overall profile that resembled the rhesus monkeys, but they had significantly higher concentrations of Gram-negative microflora in their large intestines than the rhesus monkeys. The remaining marmosets (group B) had higher concentrations of bacteria in the small intestine as compared to the large intestine, with the large intestinal concentrations being significantly lower than in the rhesus monkeys and group A marmosets. Moreover, the marmosets did not have detectable levels of aerobic Lactobacilli, and anaerobic Lactobacilli concentrations were significantly lower than in the rhesus macaques. Although it is unknown why microflora differ across species, it is likely that evolutionary adaptations in anatomy and functioning of the gastrointestinal tract influence the concentration and types of bacteria residing as the normal intestinal microflora.

Adhesion of Helicobacter pylori to yeast cells

In order to get information as to whether direct interaction of H. pylori and yeasts may modulate the course of H. pylori infections, the adhesion of H. pylori to C. albicans, C. glabrata, C. guilliermondii, C. krusei, C. parapsilosis, C. tropicalis and S. cereviseae was investigated. H. pylori adhered significantly more frequently to C. tropicalis (adhesion ratio > 10%) than to the other yeasts (adhesion ratios < 5%). On an average, no significant difference to the adhesion ratios of E. coli and S. aureus was found. Electron microscopic examinations showed that H. pylori cells contacted the cells of C. tropicalis either by knob-like structures or by close surface-to-surface adhesion. Cholesterol-depleted H. pylori cells adhered to the yeast no more than cholesterol-carrying cells. There was no indication that a direct cooperation with yeasts plays a role in H. pylori infections.

A euthymic hairless mouse model of Helicobacter pylori colonization and adherence to gastric epithelial cells in vivo

The hairless mouse strain NS:Hr/ICR was examined as a potential small animal model of Helicobacter pylori colonization, adherence to gastric epithelial cells in vivo, and gastritis. Among several small animals tested, NS:Hr/ICR mice proved to be the most highly susceptible to H. pylori infection. Challenge with clinical isolates of H. pylori consisting of either phenotype I or II (VacA and CagA positive and negative, respectively) resulted in colonization by mucus-resident and epithelial cell-adherent bacterial populations. Cell-adherent bacteria resisted 80 cycles of top-speed Vortex washing and were recovered only by homogenization of serially washed glandular stomach tissue, indicating intimate association with the mucosal surface. Immunoperoxidase staining of paraffin sections of gastric tissue from infected mice revealed H. pylori antigens localized in the glandular region of the mucosa, with some colonized areas seen in the vicinity of submucosal mononuclear cell infiltration. The latter inflammatory reaction was observed as a function of the H. pylori phenotype (only type I induced inflammation) and the challenge dose (only those mice challenged with 10(8) CFU or higher showed the reaction). The NS:Hr/ICR strain of mice is a suitable miniature model of H. pylori infection and may prove useful in the quest for an efficacious mode of treatment for this common infection in humans.