Proteomic Profiling of Acoustically Isolated Extracellular Vesicles from Blood Plasma during Murine Bacterial Sepsis.

Sepsis is a life-threatening condition caused by a dysregulated host response to an infection and is a leading cause of death worldwide. The condition is variable, which in combination with insufficient clinical markers, makes it challenging to predict when infection will progress to sepsis and to categorize patients into homogeneous patient subgroups. In this study, we demonstrate the use of acoustic trapping to rapidly enrich extracellular vesicles (EVs) from minute volumes of blood plasma from experimental mouse models of sepsis infected with the Gram-positive pathogen Streptococcus pyogenes or the Gram-negative pathogen Escherichia coli. Using quantitative mass spectrometry-based proteomics, we characterized the proteome of EVs and plasma to demonstrate that the EVs expand the observable proteome in plasma, with an emphasis on cellular processes and signaling. In our models, systemic bacterial infection altered the EV and plasma proteomes differently, with a predominant effect on proteins related to leukocyte migration in the EVs and on metabolism in the plasma. Finally, we show that E. coli infection significantly impacted metabolism, whereas S. pyogenes infection mainly affected the inflammatory response and neutrophil degranulation in our models. Collectively, our findings demonstrate that the acoustic trap facilitates access to plasma EVs, which in turn provides additional biological information which was not obtained from the plasma proteome alone.