Vacuoles of Candida yeast as a specialized niche forHelicobacter pylori

Abstract

Helicobacter pylori (H. pylori) are resistant to hostile gastric environments and antibiotic therapy, reflecting the possibility that they are protected by an ecological niche, such as inside the vacuoles of human epithelial and immune cells. Candida yeast may also provide such an alternative niche, as fluorescently labeled H. pylori were observed as fast-moving and viable bacterium-like bodies inside the vacuoles of gastric, oral, vaginal and foodborne Candida yeasts. In addition, H. pylori-specific genes and proteins were detected in samples extracted from these yeasts. The H. pylori present within these yeasts produce peroxiredoxin and thiol peroxidase, providing the ability to detoxify oxygen metabolites formed in immune cells. Furthermore, these bacteria produce urease and VacA, two virulence determinants of H. pylori that influence phago-lysosome fusion and bacterial survival in macrophages. Microscopic observations of H. pylori cells in new generations of yeasts along with amplification of H. pylori-specific genes from consecutive generations indicate that new yeasts can inherit the intracellular H. pylori as part of their vacuolar content. Accordingly, it is proposed that yeast vacuoles serve as a sophisticated niche that protects H. pylori against the environmental stresses and provides essential nutrients, including ergosterol, for its growth and multiplication. This intracellular establishment inside the yeast vacuole likely occurred long ago, leading to the adaptation of H. pylori to persist in phagocytic cells. The presence of these bacteria within yeasts, including foodborne yeasts, along with the vertical transmission of yeasts from mother to neonate, provide explanations for the persistence and propagation of H. pylori in the human population. This Topic Highlight reviews and discusses recent evidence regarding the evolutionary adaptation of H. pylori to thrive in host cell vacuoles.

Systematic review: gastric microbiota in health and disease

“…Subjects with abundant H pylori in the stomach have significantly different duodenal and oral (both oral and tongue) communities when compared to H pylori negative individuals . One study showed that healthy H pylori positive individuals have reduced oral microbiota diversity, relatively more Proteobacteria and less Fusobacteria and Firmicutes than H pylori negative individuals . Similarly, the presence of H pylori in the stomach of gastritis patients was associated with modest changes in the tongue coating microbiota, while these changes were more pronounced if the H pylori strain was cytotoxin‐associated gene A‐positive …”

“…In this study, amplification of ITS from gastric RNA failed on all 50 analysed samples indicating that yeasts do not appear to be metabolically active in the gastric environment. However, yeasts may have a particular role in facilitating survival of bacteria as endosymbiotic relationships between bacteria and yeasts has been shown including in the case of H pylori and Candida . Furthermore, fungal colonisation of the stomach appears to be more common among patients suffering from gastric ulcer or gastritis than healthy subjects …”

Interkingdom networking within the oral microbiome

“…isolated from the oral cavity of dyspeptic patients were found to contain bacteria-like bodies inside their vacuoles. These contained H. pylori -specific 16S rRNA and H. pylori proteins such as urease, vacuolating toxin (VacA), periredoxin and thiolperoxidase [67]. Fluorescence microscopy revealed H. pylori cells inside the mildly-acidic vacuoles of mother and daughter cells, suggesting that the endobacteria could multiply and transmit.…”

Association between recurrent bacterial vaginosis and Helicobacter pylori infection: a case report

“…18 This relationship may allow H pylori to colonize the vagina. Candida isolated from the vagina has been found to contain H pylori specific genes, one mechanism for the vertical transmission of H pylori.…”