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Salmonella typhi does not inhibit phagosome-lysosome fusion in human monocyte-derived macrophages
1Department of Microbiology, Meiji College of Pharmacy, Tokyo, Japan.
Abstract:
We examined phagosome-lysosome fusion in Salmonella typhi-infected human monocyte-derived macrophages and its relevance to the intracellular survival of this bacterium in vitro. S. typhi was found to survive and multiply in human monocyte-derived macrophages, whereas S. typhimurium was killed easily, indicating that the survival of Salmonella serovars is host-specific. Neither S. typhi nor S. typhimurium inhibited phagosome-lysosome fusion in human monocyte-derived macrophages. No difference between the phagosome-lysosome fusibilities of freshly prepared human monocytes and monocyte-derived macrophages was observed. These results suggest that S. typhi may survive by adapting to the conditions within fused phagolysosomes of human monocyte-derived macrophages.
Insights
Salmonella typhi survives within human macrophages, unlike Salmonella typhimurium. This suggests Salmonella typhi adapts to the phagolysosome environment for intracellular survival.
Area of Science:
- Immunology
- Microbiology
- Cell Biology
Background:
- Salmonella serovars exhibit varying intracellular survival capabilities within host macrophages.
- Phagosome-lysosome fusion is a critical cellular process for pathogen degradation.
Purpose of the Study:
- To investigate the role of phagosome-lysosome fusion in the intracellular survival of Salmonella typhi in human monocyte-derived macrophages.
- To compare the intracellular survival mechanisms of Salmonella typhi and Salmonella typhimurium in human macrophages.
Main Methods:
- Infection of human monocyte-derived macrophages with Salmonella typhi and Salmonella typhimurium.
- Assessment of bacterial survival and multiplication within macrophages.
- Evaluation of phagosome-lysosome fusion in infected macrophages.
Main Results:
- Salmonella typhi survived and multiplied in human monocyte-derived macrophages.
- Salmonella typhimurium was readily killed by human monocyte-derived macrophages.
- Neither Salmonella serovar inhibited phagosome-lysosome fusion.
- Phagosome-lysosome fusion capacity was consistent between fresh monocytes and derived macrophages.
Conclusions:
- Salmonella typhi's intracellular survival in human macrophages is host-specific.
- Salmonella typhi likely survives by adapting to the fused phagolysosome environment.
- Phagosome-lysosome fusion is not inhibited by these Salmonella serovars, suggesting alternative survival strategies for S. typhi.