Staphylococcus aureus extracellular vesicles induce apoptosis and restrain mitophagy-mediated degradation of damaged...

Area of Science:

• Microbiology
• Cell Biology
• Pathogenesis

Background:

• Extracellular vesicles (EVs) are secreted by bacteria and play roles in host-pathogen interactions.
• Pathogenic Gram-positive bacteria, including Staphylococcus aureus (S. aureus), release EVs that can cause host damage.
• Understanding the mechanisms of EV-mediated pathogenesis is crucial for developing effective treatments.

Purpose of the Study:

• To investigate the protein composition of S. aureus EVs.
• To determine the internalization pathway of S. aureus EVs into bovine mammary epithelial cells (MAC-T cells).
• To elucidate the effects of S. aureus EVs on mitochondrial function, apoptosis, and mitophagy in MAC-T cells.

Main Methods:

• Isolation and purification of S. aureus EVs.
• Liquid chromatography-tandem mass spectrometry (LC-MS/MS) for protein analysis.
• Western blot to measure MAPK and NF-κB pathway activation, apoptosis, and mitophagy markers.
• Confocal microscopy to detect mitochondrial damage and mitophagy.

Main Results:

• Purified S. aureus EVs were internalized into MAC-T cells via lipid raft-mediated endocytosis.
• S. aureus EVs induced mitochondrial damage and apoptosis in MAC-T cells.
• Mitophagy was impaired due to S. aureus EV-induced disruption of lysosomal acidity, preventing damaged mitochondria clearance.

Conclusions:

• S. aureus EVs contribute to pathogenesis by inducing immune stimulation and mitochondrial damage in bovine mammary epithelial cells.
• The EVs disrupt the lysosomal acidic environment, inhibiting Parkin-mediated mitophagy and leading to cellular damage.
• These findings provide insights into the pathogenic mechanisms of S. aureus involving extracellular vesicles.