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Organotypic hippocampal cultures. A model of brain tissue damage in Streptococcus pneumoniae meningitis
H Schmidt1, A Tlustochowska, K Stuertz
1Department of Neurology, University of Goettingen, Robert-Koch Strasse 40, D-37075 Goettingen, Germany.
Abstract:
Hippocampal slices of newborn rats were exposed to either heat-inactivated Streptococcus pneumoniae R6 (hiR6) equivalent to 10(6) and 10(8) CFU/ml, lipoteichoic acid (LTA) (0.3 microg/ml and 30 microg/ml), peptidoglycans (PG) (0.3, 30, 50 and 100 microg/ml), pneumococcal DNA (pDNA) (0.3 and 30 microg/ml) or medium only (control). Cell injury was examined by Nissl staining, Annexin V and NeuN immunohistochemistry, and quantified by propidium iodide (PI) uptake and by determining neuron-specific enolase (NSE) concentration in the culture medium. Necrotic and apoptotic cell damage occurred in all treatment groups. Overall damage (Nissl and PI staining) was most prominent after hiR6 (10(8) CFU/ml), followed by LTA (30 microg/ml), pDNA (30 microg/ml), and not detectable after PG (30 microg/ml) exposure. PG (100 microg/ml) induced severe damage. Apoptotic cells were most frequent after exposure to LTA and hiR6. Damage in the neuronal cell layers (NeuN, NSE) was most severe after treatment with hiR6 (10(8) CFU/ml), followed by PG (100 microg/ml), pDNA (30 microg/ml), and LTA (30 microg/ml).
Insights
Heat-inactivated Streptococcus pneumoniae and its components cause significant cell injury in rat hippocampal slices. Lipoteichoic acid and pneumococcal DNA also induce damage, with peptidoglycans showing dose-dependent effects.
Area of Science:
- Neuroscience
- Immunology
- Microbiology
Background:
- Bacterial components can trigger inflammatory responses in the central nervous system.
- Understanding the specific effects of Streptococcus pneumoniae components on neuronal cells is crucial for developing therapeutic strategies.
Purpose of the Study:
- To investigate the neurotoxic effects of heat-inactivated Streptococcus pneumoniae R6 (hiR6) and its purified components on newborn rat hippocampal slices.
- To determine the dose-dependent and component-specific injury patterns.
Main Methods:
- Hippocampal slices were exposed to varying concentrations of hiR6, lipoteichoic acid (LTA), peptidoglycans (PG), and pneumococcal DNA (pDNA).
- Cell injury was assessed using Nissl staining, Annexin V, NeuN immunohistochemistry, propidium iodide (PI) uptake, and neuron-specific enolase (NSE) concentration.
Main Results:
- Necrotic and apoptotic cell damage was observed across all treatment groups.
- Heat-inactivated Streptococcus pneumoniae (10^8 CFU/ml) caused the most prominent overall damage.
- Lipoteichoic acid and pneumococcal DNA also induced significant neuronal damage, while peptidoglycans showed severe damage only at high concentrations (100 microg/ml).
- Apoptotic cell death was highest following exposure to LTA and hiR6.
Conclusions:
- Streptococcus pneumoniae components, particularly hiR6, LTA, and pDNA, exert significant neurotoxic effects on developing hippocampal neurons.
- The study highlights the differential neurotoxicity of various bacterial components, with implications for understanding pneumococcal meningitis pathogenesis.