Impairment of brain mitochondrial functions by β-hemolytic Group B Streptococcus. Effect of cardiolipin and...

Area of Science:

• Neuroscience
• Microbiology
• Biochemistry

Background:

• Group B Streptococcus (GBS) is a significant cause of central nervous system infections.
• Understanding GBS's impact on neuronal energy production is crucial for developing therapeutic strategies.

Purpose of the Study:

• To investigate the effects of GBS infection on brain mitochondrial function.
• To identify the specific GBS virulence factors responsible for mitochondrial damage.
• To explore potential protective mechanisms against GBS-induced mitochondrial dysfunction.

Main Methods:

• Isolated brain mitochondria were exposed to GBS strains with and without β-hemolysin expression.
• Mitochondrial membrane potential (Δψm), oxygen consumption, ATP synthesis, and cytochrome c release were measured.
• Phospholipid composition was analyzed using MALDI-TOF mass spectrometry.
• The effects of exogenous cardiolipin (CL) and dipalmitoylphosphatidylcholine (DPPC) were assessed.

Main Results:

• GBS strains expressing β-hemolysin dissipated mitochondrial membrane potential (Δψm), indicating loss of reducing power.
• GBS infection led to increased oxygen consumption, uncoupled respiration, inhibited ATP synthesis, and cytochrome c release.
• Mitochondrial Ca(2+) uptake control systems were compromised.
• Exogenous CL and DPPC attenuated GBS-induced mitochondrial uncoupling through distinct mechanisms.

Conclusions:

• β-hemolysin is a key GBS virulence factor that directly impairs brain mitochondrial function.
• GBS disrupts critical mitochondrial processes including energy production and calcium homeostasis.
• Cardiolipin and DPPC show potential as therapeutic agents by mitigating GBS-induced mitochondrial damage.