Spatio-temporal brain invasion pattern of Streptococcus pneumoniae and dynamic changes in the cellular environment in...

Area of Science:

• Neuroscience
• Infectious Diseases
• Microbiology

Background:

• Streptococcus pneumoniae is a leading cause of bacterial meningitis globally.
• Pneumococcal meningitis can result in severe, long-term neurological sequelae affecting sensorimotor functions.
• The precise invasion patterns of pneumococci within the brain remain poorly understood.

Purpose of the Study:

• To investigate the invasion pattern of Streptococcus pneumoniae within the brain during meningitis.
• To understand the early neuropathological changes induced by pneumococcal infection in the brain.

Main Methods:

• Utilized a bacteremia-derived meningitis mouse model.
• Employed 3D whole brain imaging techniques.
• Performed brain microdissection to analyze bacterial distribution and host response.

Main Results:

• Identified equal involvement of all brain regions during disease progression.
• Observed pneumococci closely associated with the brain's microvasculature.
• Detected microglial activation in the hippocampus and increased neuroblast proliferation/migration in the neurogenic niche.
• Found high bacterial load and neuroinflammation throughout the brain prior to symptom onset.

Conclusions:

• Streptococcus pneumoniae disseminates widely throughout the brain early in meningitis.
• Pneumococcal meningitis triggers neuroinflammation and cell death, impairing the brain's regenerative capacity.
• Early bacterial invasion and associated pathology contribute to the neurological deficits seen in pneumococcal meningitis.