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Growth in vascular cells and cytokine production by Chlamydia pneumoniae
1Division of Infectious Diseases, Johns Hopkins University, Baltimore, MD 21205. cgaydos@welch.jhu.edu
Abstract:
The proposed pathogenesis of Chlamydia pneumoniae in atherosclerosis is supported by the finding that C. pneumoniae can initiate and sustain growth in human vascular cells. In vitro growth of C. pneumoniae is found in macrophages, peripheral blood monocyte (PBMC)-derived macrophages, endothelial cells, and aortic artery smooth muscle cells. U-937 macrophages infected with C. pneumoniae are capable of transmitting the infection to human coronary artery endothelial cells (CAEC) with direct cellular contact. Production of cytokines by cells infected with C. pneumoniae indicates that the organism can stimulate the immune system. CAEC infected with C. pneumoniae produce more interleukin-8 than cells sham inoculated with negative control cells. When interferon-gamma is used to stimulate HEp-2 cells, U-937 cells, and PBMC (before infection with C. pneumoniae), inhibition of a productive growth cycle occurs in a dose-related response. Studies are needed to learn the relationship between productive infection and persistence, the ability of C. pneumoniae to affect the immune response, and the potential for C. pneumoniae to influence atheromatous lesions.
Insights
Chlamydia pneumoniae can grow in human vascular cells, supporting its role in atherosclerosis. This infection stimulates immune responses and may influence atheromatous lesion development.
Area of Science:
- Infectious diseases
- Vascular biology
- Immunology
Background:
- Chlamydia pneumoniae is implicated in atherosclerosis pathogenesis.
- Understanding its interaction with vascular cells is crucial.
Purpose of the Study:
- To investigate the in vitro growth and transmission of C. pneumoniae in human vascular cells.
- To determine the immune response stimulated by C. pneumoniae infection.
Main Methods:
- In vitro culture of C. pneumoniae in macrophages, PBMCs, endothelial cells, and smooth muscle cells.
- Assessing infection transmission between cell types.
- Measuring cytokine production (e.g., interleukin-8) and the effect of interferon-gamma on C. pneumoniae growth.
Main Results:
- C. pneumoniae successfully initiated and sustained growth in various human vascular cells.
- Infected macrophages transmitted C. pneumoniae to endothelial cells via direct contact.
- Infection stimulated cytokine production, including increased interleukin-8 in CAEC.
- Interferon-gamma inhibited C. pneumoniae productive growth in a dose-dependent manner.
Conclusions:
- C. pneumoniae can infect and persist in human vascular cells, supporting its role in atherosclerosis.
- The organism can modulate the immune response through cytokine production.
- Further research is needed on infection persistence, immune effects, and atheromatous lesion influence.