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Published on: December 16, 2019
Interaction of Chlamydiae with human macrophages
1Biocenter, Department of Microbiology, University of Würzburg, Germany.
Abstract:
The phylum Chlamydiae contains several members that are well-known human pathogens, like Chlamydia trachomatis and C. pneumoniae. Establishing a chronic bacterial infection requires the active evasion of the host immune response. A major arm of the innate immune defence is constituted by macrophages, which fight infections by removing bacteria and triggering an adaptive immune response. However, some pathogenic Chlamydia infect and survive in macrophages at least for a certain period of time. Therefore, macrophages can serve as vehicles for the dissemination of bacterial infections from the primary infection site via the urogenital or respiratory tract to distant sites in the body. The capacity to infect macrophages seems to depend on the chlamydial strain and the source of macrophages. In vitro infections of macrophages with C. trachomatis, C. psittaci and C. pneumoniae reveal low efficiency of infection and progeny formation, as well as failure to develop mature inclusions. In contrast, the emerging pathogen, Simkania negevensis, actively replicates in macrophages. Here we summarize the current knowledge of the intracellular and molecular key mechanisms of C. trachomatis, C. pneumoniae and S. negevensis infections in human macrophages.
Insights
Certain Chlamydia bacteria evade immune cells called macrophages. Unlike common pathogens Chlamydia trachomatis and Chlamydia pneumoniae, the emerging Simkania negevensis actively replicates within these crucial immune cells.
Area of Science:
- Microbiology
- Immunology
- Pathogenesis
Background:
- Chlamydiae are significant human pathogens, including Chlamydia trachomatis and Chlamydia pneumoniae.
- Macrophages are key innate immune cells that phagocytose and eliminate pathogens.
- Some Chlamydia species can infect and survive within macrophages, potentially aiding systemic dissemination.
Purpose of the Study:
- To review the intracellular and molecular mechanisms of Chlamydia infections in human macrophages.
- To compare the macrophage infectivity of established Chlamydia pathogens with emerging Simkania negevensis.
Main Methods:
- In vitro infection models using human macrophages.
- Analysis of bacterial replication, inclusion formation, and host-pathogen interactions.
- Comparative study of Chlamydia trachomatis, Chlamydia pneumoniae, and Simkania negevensis.
Main Results:
- Chlamydia trachomatis, Chlamydia psittaci, and Chlamydia pneumoniae exhibit low infection efficiency and limited replication in macrophages.
- Simkania negevensis demonstrates active replication within macrophages, unlike other studied Chlamydia species.
- Macrophage infection dynamics vary depending on the Chlamydia strain and macrophage source.
Conclusions:
- Macrophages can be exploited by certain Chlamydia species for survival and dissemination.
- Simkania negevensis possesses distinct mechanisms for successful intracellular replication in macrophages.
- Understanding these host-pathogen interactions is crucial for developing therapeutic strategies against chlamydial infections.
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