Vacuoles of Acanthamoeba Castellanii Behave As a Specialized Shelter (Host) for Helicobacter Pylori Publisher



Alipour N^{1, 2} ; Gaeini N³ ; Taner A⁴ ; Yildiz F¹ ; Masseret S⁵ ; Malfertheiner P⁶ Show Affiliations
Source: Helicobacter Published:2015

Abstract

Background: 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. Acanthamoeba castellanii 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-fecal and water–food-borne Acanthamoeba castellanii. In addition, H. pylori-specific genes and proteins were detected in samples extracted from these ameba cells. The coccoid forms of H. pylori present within this ameba are converted to spiral form and 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 ameba along with amplification of H. pylori-specific genes from consecutive generations indicate that new ameba can inherit the intracellular H. pylori as part of their vacuolar content. Accordingly, it is proposed that Acanthamoeba vacuoles serve as sophisticated niche that protects H. pylori against the environmental stresses and provides essential nutrients for its growth and multiplication. This intracellular establishment inside the Acanthamoeba vacuole likely occurred long ago, leading to the adaptation of H. pylori to persist in phagocytic cells. The presence of these bacteria within Acanthamoeba, along with the transmission of Acanthamoeba from sewage, saliva water to others, provides explanations for the persistence and propagation of H. pylori in the human population. Objective: This topic highlights the reviews and discusses recent evidence regarding the evolutionary adaptation of H. pylori to thrive in host cell vacuoles. Method and Results: Helicobacter pylori (H. pylori) have been observed within Acanthamoeba vacuoles by light and fluorescence microscopy, and their presence has been confirmed by the detection of H. pylori-specific genes and proteins in Acanthamoeba extracts, such as vacA subunits, ureA, peroxiredoxin, and thiol peroxidase. Moreover, nonculturable H. pylori cells have been found in subsequent generations of Acanthamoeba, indicating the generational transmission of the bacteria as part of the transfer of vacuolar content. Conclusion: H.pylori are therefore well equipped to establish in the vacuoles of Acanthamoeba, which provide them with essential nutrients for multiplication, as a pre-adaptation for invasion of human cells. Due to general tropism of all bacteria to yeast extract, entrance of H. pylori into candida was modified by our experiments and it is corrected to “Acanthamoeba”. © 2015 John Wiley & Sons Ltd, Helicobacter.