Immunostimulatory Potential of Staphylococcus aureus-Derived Vesicles in the Context of Infective Endocarditis
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| Year of publication | 2025 |
| Type | Conference abstract |
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| Description | Infective endocarditis (IE) is a severe inflammatory disease of the heart's inner lining, primarily caused by gram-positive bacteria such as Streptococcus, Staphylococcus, and Enterococcus, accounting for 80–90% of cases. Recent research has highlighted the role of bacterial extracellular vesicles (bEVs) as potential contributors to bacterial virulence and immune modulation.This study focuses on bEVs derived from a clinical strain of Staphylococcus aureus 3.496, characterized by whole genome sequencing using Oxford Nanopore Technologies. bEVs were isolated through a series of centrifugation, filtration, ultracentrifugation, and sucrose cushion purification steps. Comprehensive characterization was conducted using nanoparticle tracking analysis (NTA), cryo-electron microscopy (Cryo-EM), FTIR spectroscopy, Western blotting, and protein quantification. Functional assays revealed that stimulation of RAW264.7 macrophages with purified bEVs significantly increased the production of proinflammatory mediators, including TNF?, IL-6, nitric oxide, and inducible nitric oxide synthase (iNOS). The vesicles, approximately 80 nm in diameter with a lipid bilayer structure, triggered a pronounced inflammatory response, suggesting their role in host immune activation. These findings support the involvement of Staphylococcus aureus-derived bEVs in the pathogenesis of IE, with ongoing proteomic analyses aimed at identifying associated virulence factors within the vesicular cargo. |