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Minimal effect of advanced aging on susceptibility of mice to infection with Mycobacterium tuberculosis
1Trudeau Institute, Inc., Saranac Lake, New York 12983.
Abstract:
Young (3-month-old) and old (> or = 24-month-old) mice of a long-lived strain were compared in terms of their ability to resist infection with Mycobacterium tuberculosis. There was little overall difference in the ability of young and old mice to resist this infection. Mice in both age groups could control infection in their livers and spleens by a mechanism that was predominantly CD4+ T cell-mediated but not in their lungs. Again, old mice were almost as capable as young mice at being immunized by bacille Calmette-Guérin against a challenge infection with M. tuberculosis. The results argue against including M. tuberculosis among infectious agents to which mice become susceptible with advanced age.
Insights
Aging does not significantly impact resistance to Mycobacterium tuberculosis infection in mice. Both young and old mice effectively controlled infections in organs like the liver and spleen, suggesting M. tuberculosis susceptibility does not increase with age.
Area of Science:
- Immunology
- Infectious Diseases
- Gerontology
Background:
- Aging can alter immune responses and susceptibility to infections.
- Mycobacterium tuberculosis (M. tuberculosis) is a significant human pathogen.
- Understanding age-related changes in host defense is crucial for public health.
Purpose of the Study:
- To investigate the impact of aging on the ability of mice to resist M. tuberculosis infection.
- To compare the immune control mechanisms in young versus old mice.
- To assess the efficacy of bacille Calmette-Guérin (BCG) immunization in aged mice.
Main Methods:
- Comparison of infection resistance in young (3-month-old) and old (>= 24-month-old) mice.
- Assessment of M. tuberculosis burden in liver, spleen, and lungs.
- Evaluation of CD4+ T cell-mediated immunity.
- Testing BCG immunization efficacy against M. tuberculosis challenge.
Main Results:
- Little overall difference in M. tuberculosis resistance between young and old mice.
- Both age groups controlled infection in the liver and spleen via CD4+ T cell-dependent mechanisms.
- Pulmonary infection control was not observed in either age group.
- Old mice were effectively immunized by BCG, similar to young mice.
Conclusions:
- M. tuberculosis infection susceptibility does not appear to increase with advanced age in this mouse model.
- CD4+ T cell-mediated immunity plays a key role in controlling M. tuberculosis in the liver and spleen.
- Aging does not significantly impair the ability to mount an adaptive immune response to M. tuberculosis or BCG vaccination.
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