Multiparametric Extracellular Vesicle Profiling Identifies a Distinct Circulating Signature of Bicuspid Aortic Valve Disease

Background: Bicuspid aortic valves (BAV) are at higher risk for early-onset and more aggressive calcific aortic valve disease (CAVD) compared to tricuspid aortic valves (TAV). Extracellular vesicles (EVs) can provide insight into the molecular drivers of BAV-associated CAVD. Researchers used a combination of techniques to analyze EVs in patients with BAV and TAV.

Methods: The study measured the abundance and morphology of large extracellular vesicles (LEV) using nano-flow cytometry and super-resolution microscopy. Additionally, proteomic profiling was performed to identify the molecular contents of LEVs and associated biological pathways in BAV and TAV patients.

Results: The study found that patients with BAV had distinct circulating LEV profiles compared to TAVs. Super-resolution imaging revealed specific organization of adhesion molecules on LEVs that was unique to BAV. Proteomic analysis identified a previously unrecognized neutrophil-associated signature in BAV LEVs, enriched for proteins involved in neutrophil degranulation and innate immunity.

This finding was associated with alterations in platelet- and neutrophil-associated LEV populations in BAV patients, indicating enhanced thrombo-inflammatory activity. Furthermore, specific associations between LEV populations and clinical parameters in BAV and TAV suggest that LEV profiles reflect the morphology-specific aspects of disease severity.

Conclusions: This comprehensive analysis of single-vesicle and bulk proteomic profiling revealed a unique circulating LEV signature in BAV-associated CAVD. This signature is characterized by endothelial activation and reciprocal platelet-neutrophil interactions, highlighting previously unrecognized differences between BAV and TAV. These findings suggest that LEV analysis could serve as a potential biomarker for valve morphology-specific pathophysiology in CAVD.