Brain Infection by Group B Streptococcus Induces Inflammation and Affects Neurogenesis in the Adult Mouse Hippocampus

Area of Science:

• Neuroscience
• Infectious Diseases
• Cellular Biology

Background:

• Central nervous system infections cause significant neuronal damage and neuroinflammation.
• Bacterial brain infections, particularly, lead to hippocampal neuronal degeneration.
• Adult hippocampal neurogenesis is a vital repair process potentially compensating for neuronal loss.

Purpose of the Study:

• To investigate the impact of Group B Streptococcus (GBS) infection on adult hippocampal neurogenesis.
• To establish an adult mouse model for studying GBS-induced brain infection and its effects.

Main Methods:

• Utilized a GBS strain (NEM316) to induce experimental encephalitis in adult mice.
• Assessed neurological deficits, mortality, inflammation, and neurogenesis in the hippocampus.
• Differentiated effects on hippocampal neurogenesis versus subventricular zone neurogenesis.

Main Results:

• GBS encephalitis caused neurological deficits, inflammation, and increased mortality.
• Adult hippocampal neurogenesis was significantly suppressed, specifically in the dentate gyrus.
• Progenitor cell proliferation and new neuron generation in the hippocampus were inhibited.
• Neurogenesis in the subventricular zone remained unaffected by the infection.

Conclusions:

• GBS brain infection detrimentally affects adult hippocampal neurogenesis.
• The study highlights the vulnerability of endogenous repair mechanisms in the hippocampus to bacterial encephalitis.
• These findings offer new insights into the neuropathology of GBS infections and their impact on brain plasticity.