Organotypic hippocampal cultures: A model of brain tissue damage in Streptococcus pneumoniae meningitis

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 μg/ml and 30 μg/ml), peptidoglycans (PG) (0.3, 30, 50 and 100 μg/ml), pneumococcal DNA (pDNA) (0.3 and 30 μg/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 μg/ml), pDNA (30 μg/ml), and not detectable after PG (30 μg/ml) exposure. PG (100 μg/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 μg/ml), pDNA (30 μg/ml), and LTA (30 μg/ml).