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Viability of Mycobacterium leprae inside macrophages from different strains of mice and possible genetic control
I Nair1, D Varadkar, P R Mahadevan
1Foundation for Medical Research, Worli, Bombay, India.
Abstract:
Peritoneal macrophages from Swiss white mice in vitro tolerated Mycobacterium leprae and allowed metabolism of the bacteria leading to release of bacteria-specific antigenic protein. This was associated with the maintenance of viability of the bacilli inside the cells. Macrophages from C57BL mice reduced viability of M. leprae after phagocytosis, and this was associated with the production of superoxide. Blockage of superoxide production resulted in maintaining viability of the cells of these mouse strains. Associated with loss of viability of the bacilli is the absence of the production of antigenic protein in the lysate. Interestingly, the maintenance of viability or loss of viability and the factors controlling such viability in the macrophages of Swiss white and C57BL mice, respectively, appeared to be genetically controlled.
Insights
Mice macrophages show different responses to Mycobacterium leprae (M. leprae). Swiss white mice macrophages support M. leprae viability and antigen release, while C57BL mice macrophages reduce viability via superoxide production, a trait controlled by genetics.
Area of Science:
- Immunology
- Microbiology
- Genetics
Background:
- Macrophages play a crucial role in the host immune response to microbial infections.
- Mycobacterium leprae (M. leprae) is the causative agent of leprosy, a complex infectious disease.
- Understanding host-pathogen interactions at the cellular level is key to developing effective treatments.
Purpose of the Study:
- To investigate the differential in vitro responses of peritoneal macrophages from two distinct mouse strains (Swiss white and C57BL) to Mycobacterium leprae.
- To elucidate the role of superoxide production in macrophage-mediated control of M. leprae viability.
- To explore the genetic basis for the observed differences in macrophage-pathogen interactions.
Main Methods:
- In vitro culture of peritoneal macrophages from Swiss white and C57BL mice.
- Exposure of macrophages to Mycobacterium leprae.
- Assessment of bacterial viability and metabolism within macrophages.
- Measurement of superoxide production by macrophages.
- Inhibition of superoxide production to evaluate its effect on bacterial viability.
Main Results:
- Swiss white mouse macrophages tolerated M. leprae, maintaining bacterial viability and releasing specific antigenic proteins.
- C57BL mouse macrophages reduced M. leprae viability post-phagocytosis, correlating with superoxide production.
- Blocking superoxide production in C57BL macrophages preserved M. leprae viability.
- Loss of M. leprae viability in C57BL macrophages was associated with absent antigenic protein production.
- The differential control of M. leprae viability by macrophages appeared to be genetically determined.
Conclusions:
- Macrophage response to M. leprae differs significantly between Swiss white and C57BL mice, indicating strain-specific immune mechanisms.
- Superoxide production is a critical factor in C57BL macrophage-mediated control of M. leprae viability.
- Genetic factors likely govern the divergent macrophage responses and M. leprae handling in these mouse strains.
- These findings provide insights into the genetic basis of host susceptibility or resistance to M. leprae infection.