Evidence of systemic dissemination of Chlamydia pneumoniae via macrophages in the mouse
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Updated: Oct 29, 2026
Alveolar Macrophage Phagocytosis and Bacteria Clearance in Mice
Published on: March 2, 2019
T C Moazed1, C C Kuo, J T Grayston
1Department of Pathobiology, University of Washington, Seattle 98195, USA.
Abstract:
Chlamydia pneumoniae has been postulated to cause systemic disease by infection of monocytes/macrophages and spread via the blood or lymphatics. To investigate how C. pneumoniae disseminates, the ability of the organism to infect murine macrophages in vivo and whether infection can be transferred via macrophages were determined. C. pneumoniae was detected by direct plating, isolation, and polymerase chain reaction in alveolar macrophages from intranasally inoculated mice and peritoneal macrophages from intraperitoneally inoculated mice. C. pneumoniae were also detected in peripheral blood mononuclear cells, but not plasma, of intranasally and intraperitoneally inoculated mice. When alveolar or peritoneal macrophages were adoptively transferred by intraperitoneal injection from infected to uninfected mice, C. pneumoniae DNA was detected by polymerase chain reaction in lung, thymus, spleen, and/or abdominal lymph nodes. These results demonstrate the ability of C. pneumoniae to infect macrophages in vivo and to disseminate systemically via infected macrophages by hematogenous and lymphatic routes.
Insights
Chlamydia pneumoniae infects macrophages in mice, spreading the bacteria throughout the body. This study shows infected macrophages can transfer Chlamydia pneumoniae to distant organs via blood and lymph.
Area of Science:
- Infectious Diseases
- Immunology
- Microbiology
Background:
- Chlamydia pneumoniae is suspected to cause systemic illness by infecting monocytes/macrophages.
- The dissemination routes of C. pneumoniae remain incompletely understood.
Purpose of the Study:
- To investigate the in vivo infection of murine macrophages by C. pneumoniae.
- To determine if C. pneumoniae infection can be transferred via macrophages.
Main Methods:
- Mice were inoculated intranasally or intraperitoneally with C. pneumoniae.
- Detection of C. pneumoniae utilized direct plating, isolation, and PCR in macrophages and peripheral blood mononuclear cells.
- Adoptive transfer of infected macrophages was performed to assess systemic spread.
Main Results:
- C. pneumoniae was detected in alveolar and peritoneal macrophages of infected mice.
- Bacterial DNA was found in peripheral blood mononuclear cells, but not plasma.
- Adoptively transferred macrophages transmitted C. pneumoniae DNA to lungs, thymus, spleen, and lymph nodes.
Conclusions:
- C. pneumoniae can infect macrophages in vivo.
- Infected macrophages facilitate systemic dissemination of C. pneumoniae through hematogenous and lymphatic pathways.
