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Legionella pneumophila replicates within rat alveolar epithelial cells
C H Mody1, R Paine, M S Shahrabadi
1Department of Internal Medicine, University of Calgary, Canada.
The Journal of Infectious Diseases
|May 1, 1993
Summary
Legionella pneumophila can replicate in lung epithelial cells, not just macrophages. This finding helps explain how this bacterium causes legionnaires
Area of Science:
- Microbiology
- Cell Biology
- Pathogenesis
Background:
- Legionella pneumophila causes legionnaires' pneumonia by replicating in the lungs.
- While typically found in macrophages, activated immune cells inhibit L. pneumophila proliferation.
- This suggests L. pneumophila may utilize alternative host cells to evade immune responses.
Purpose of the Study:
- To investigate if pulmonary alveolar epithelial cells serve as a replication site for Legionella pneumophila.
- To understand the role of epithelial cells in the pathogenesis of legionnaires' disease.
Main Methods:
- Primary cultures of rat pulmonary alveolar epithelial cells were used.
- Double-label immunofluorescence and electron microscopy confirmed intracellular L. pneumophila.
- Replication rates were compared between epithelial cells and alveolar macrophages in various media.
Main Results:
- Legionella pneumophila successfully replicated within primary cultures of rat pulmonary alveolar epithelial cells.
- Intracellular replication was observed in epithelial cells, requiring viable cells and occurring in both serum-free and serum-containing media.
- Replication was enhanced in the presence of serum and required similar cell numbers as alveolar macrophages.
Conclusions:
- Pulmonary alveolar epithelial cells represent a viable alternative host cell for Legionella pneumophila replication in the lung.
- This intracellular replication in epithelial cells may contribute to the pathogenesis of legionnaires' disease.
- Identifying alternative replication sites provides new insights into L. pneumophila evasion strategies.