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Interaction of Mycoplasma pneumoniae with HeLa cells
1Department of Microbiology, University of Georgia, Athens 30602.
Abstract:
The susceptibility of HeLa cells to Mycoplasma pneumoniae-induced injury was examined. Infections were initiated with relatively low mycoplasma doses, carried out in a culture medium incapable of supporting M. pneumoniae replication in the absence of host cells, and monitored for up to 10 days. Under these conditions, a time- and dose-dependent decline in the number of viable host cells compared with that of uninfected controls was observed. The effect of M. pneumoniae infection on host cell macromolecular synthesis was also evaluated. At high doses of infection, synthesis of both protein and RNA declined rapidly relative to that in control cells. At lower doses there was a biphasic response in protein synthesis, which was substantially lower than that in the uninfected control by day 1 postinfection, returned to control levels by day 4 postinfection, and was again less than that in control cells by day 7 postinfection. In contrast, no transient recovery was observed in RNA synthesis, which declined very gradually over 7 days in infected HeLa cells compared with that in uninfected control cells. The ability of HeLa cells to support the proliferation of M. pneumoniae under these experimental conditions was demonstrated by quantitation of mycoplasma CFU in the nonpermissive medium in the presence or absence of HeLa cells. A negligible increase in the number of M. pneumoniae was observed over 4 days when HeLa cells were absent, while CFU increased by almost 20-fold when M. pneumoniae was cultured in the presence of HeLa cells. The susceptibility and response in macromolecular synthesis in M. pneumoniae-infected HeLa cells differed from that recently described for a nontransformed culture of hamster trachea epithelial cells under the same experimental conditions (Y.-Y. Chen and D.C. Krause, Infect. Immun. 56: 570-576, 1988), underscoring the importance of the choice of host cell for in vitro modeling of M. pneumoniae pathogenesis.
Insights
HeLa cells show susceptibility to Mycoplasma pneumoniae, with infection causing a decline in cell viability and macromolecular synthesis. Host cell choice is crucial for modeling M. pneumoniae pathogenesis in vitro.
Area of Science:
- Microbiology
- Cell Biology
- Pathogenesis Research
Background:
- Mycoplasma pneumoniae is a significant human pathogen.
- Understanding host cell responses to M. pneumoniae is crucial for developing effective treatments.
- HeLa cells are a widely used model for studying cellular responses to infection.
Purpose of the Study:
- To investigate the susceptibility of HeLa cells to Mycoplasma pneumoniae-induced injury.
- To evaluate the impact of M. pneumoniae infection on HeLa cell viability and macromolecular synthesis.
- To compare the response of HeLa cells to M. pneumoniae with other host cell models.
Main Methods:
- HeLa cells were infected with M. pneumoniae at low doses in a non-permissive medium for up to 10 days.
- Cell viability was assessed by counting viable host cells.
- Macromolecular synthesis (protein and RNA) was measured.
- Mycoplasma pneumoniae colony-forming units (CFU) were quantified to confirm proliferation.
Main Results:
- A time- and dose-dependent decrease in viable HeLa cells was observed post-infection.
- High M. pneumoniae doses led to rapid declines in protein and RNA synthesis.
- Lower doses showed a biphasic response in protein synthesis, with a transient recovery.
- RNA synthesis showed a gradual decline without transient recovery.
- HeLa cells supported M. pneumoniae proliferation, evidenced by a 20-fold increase in CFU.
Conclusions:
- HeLa cells are susceptible to M. pneumoniae-induced injury.
- M. pneumoniae infection affects host cell macromolecular synthesis in a dose-dependent manner.
- The response of HeLa cells differs from other host cell models, highlighting the importance of host cell selection in M. pneumoniae pathogenesis studies.