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Measuring Bacterial Load and Immune Responses in Mice Infected with Listeria monocytogenes
Published on: August 9, 2011
Infection of murine fetal brain cell cultures with Listeria monocytogenes
M Peters1, M Hewicker-Trautwein
1Institute of Microbiology and Infectious Diseases of Animals, School of Veterinary Medicine, Hannover, Germany.
Abstract:
The uptake of Listeria monocytogenes by different brain cells was studied in primary dissociated brain cell cultures derived from murine fetuses. In respect to the supposed intraaxonal migration of Listeria monocytogenes in the pathogenesis of listeric focal brain stem encephalitis, it was examined whether the bacterium was internalized by neurons. Infection rates of distinct cell types were determined by double immunofluorescence with antibodies against cell type-specific markers and the bacterial pathogen. Because of the changing composition of the cultures and time-dependent expression of the oligodendrocyte marker galactocerebroside (GC), infections were carried out on day 4, 6, 8, and 15 in vitro. Listeria monocytogenes was detected predominantly within macrophages. Astrocytes, oligodendrocytes, and fibronectin-expressing cells were infected to a lesser extent. The lowest rates of infection were observed in neurons. A tropism of Listeria monocytogenes for neurons was not detected in vitro.
Insights
Listeria monocytogenes primarily infects macrophages in the brain, with lower rates in astrocytes and oligodendrocytes. This study found no evidence of Listeria monocytogenes tropism for neurons in vitro.
Area of Science:
- Neuroscience
- Microbiology
- Immunology
Background:
- Listeria monocytogenes can cause listeric focal brain stem encephalitis.
- Intraaxonal migration of Listeria monocytogenes is a proposed mechanism in encephalitis pathogenesis.
- Understanding bacterial entry into different brain cell types is crucial.
Purpose of the Study:
- To investigate the uptake of Listeria monocytogenes by various primary murine brain cells in vitro.
- To determine if neurons internalize Listeria monocytogenes, a key question for encephalitis pathogenesis.
- To assess the tropism of Listeria monocytogenes for specific neural cell populations.
Main Methods:
- Primary dissociated murine fetal brain cell cultures were used.
- Infection rates were quantified using double immunofluorescence.
- Cell-specific markers and antibodies against Listeria monocytogenes were employed.
- Cultures were analyzed at multiple time points (days 4, 6, 8, 15 in vitro).
Main Results:
- Listeria monocytogenes was predominantly found within macrophages.
- Astrocytes, oligodendrocytes, and fibronectin-expressing cells showed lower infection rates.
- Neurons exhibited the lowest rates of Listeria monocytogenes infection.
- No significant tropism for neurons was observed in vitro.
Conclusions:
- Macrophages are the primary brain cell type infected by Listeria monocytogenes in this model.
- Neurons are not a preferred target for Listeria monocytogenes in vitro.
- The findings suggest alternative pathways for Listeria monocytogenes neuroinvasion or pathogenesis.
