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Mycobacterium tuberculosis invades and replicates within type II alveolar cells
1Kuzell Institute for Arthritis & Infectious Diseases, California Pacific Medical Center Research Institute, San Francisco, USA.
Infection and Immunity
|April 1, 1996
Summary
Mycobacterium tuberculosis invades human alveolar epithelial cells, challenging the assumption of macrophage-only infection. This invasion, dependent on specific cell receptors and host cell cytoskeleton, suggests a role in lung infection pathogenesis.
Area of Science:
- Microbiology
- Cell Biology
- Pathogenesis Research
Background:
- Mycobacterium tuberculosis primarily infects alveolar macrophages.
- Alveolar epithelial cells may also interact with M. tuberculosis upon inhalation.
Purpose of the Study:
- To investigate the in vitro binding and invasion capabilities of M. tuberculosis with alveolar epithelial cells.
- To explore the mechanisms and host cell receptors involved in M. tuberculosis entry.
Main Methods:
- Utilized A549 human type II alveolar cell line and M. tuberculosis H37Rv/H37Ra strains.
- Performed adherence and invasion assays at different temperatures.
- Investigated the role of CD51, CD29 integrins, microtubules, and microfilaments in invasion.
Main Results:
- M. tuberculosis H37Rv efficiently invaded A549 cells compared to other strains and bacteria.
- Invasion was temperature-dependent (37°C > 30°C).
- Binding was inhibited by anti-CD51 and anti-CD29 antibodies, indicating integrin involvement.
- Uptake was dependent on microtubules and microfilaments, suggesting distinct invasion pathways.
Conclusions:
- M. tuberculosis can invade type II alveolar epithelial cells.
- Alveolar epithelial cell invasion may contribute to the pathogenesis of tuberculosis.
- Identified specific host cell receptors and cytoskeletal elements involved in M. tuberculosis entry.