Beta-Lactam Antibiotics Promote Extracellular Vesicle Production of Staphylococcus aureus Through ROS-Mediated Lipid...

Area of Science:

• Microbiology
• Biotechnology
• Drug Discovery

Background:

• Bacterial extracellular vesicles (EVs) are valuable for bioproducts like vaccines and drug delivery.
• Low natural EV yield from bacteria limits their widespread application.
• Staphylococcus aureus EVs hold potential for therapeutic and diagnostic uses.

Purpose of the Study:

• To investigate methods for enhancing bacterial EV production.
• To elucidate the mechanisms by which sub-minimum inhibitory concentration (MIC) β-lactams increase EV yield in Staphylococcus aureus.
• To evaluate the potential of modified EVs in an immunological context.

Main Methods:

• Treatment of Staphylococcus aureus strains with sub-MIC β-lactam antibiotics.
• Analysis of penicillin-binding protein (PBP) gene expression.
• Assessment of reactive oxygen species (ROS) production.
• Transcriptomic and lipidomic analyses.
• Evaluation of EV-loaded proteins and immunogenicity in mice.

Main Results:

• Sub-MIC β-lactams, specifically oxacillin (OXA), significantly boosted EV production in S. aureus.
• β-lactam treatment increased PBP gene expression and ROS levels, with PBP inactivation promoting EV secretion.
• OXA-induced ROS triggered lipid metabolic reprogramming, including increased lipid peroxidation, phosphatidic acid, and lipoteichoic acid biosynthesis, contributing to EV generation.
• EVs from OXA-treated bacteria showed altered protein cargo and enhanced Dengue EDIII-specific antibody induction in mice.

Conclusions:

• Sub-MIC β-lactams are effective in enhancing bacterial EV production through a ROS-dependent pathway involving lipid metabolism.
• Targeting PBP and modulating ROS levels presents a viable strategy to increase bacterial EV yield.
• Modified bacterial EVs demonstrate potential for improved immunogenicity, supporting their development for vaccines and other bioproducts.