Extracellular vesicle size in early sepsis
Jaehne AK, Golembieski W, Kemper A, Osobamiro O, Cheung WL, Buller B, Zhang ZG, Chopp M, Rivers EP, and Morris D. Extracellular vesicle size in early sepsis. Shock 2019; 51(6 Suppl 1):133.
Introduction: Sepsis continues to be a disease with high mortality and morbidity. Pathophysiologic understanding continues to be limited. Research has focused in the past on freely circulating inflammatory cells, cytokines, RNAs and DNAs without yielding much insight into the complex processes of these entities in the development of multiorgan dysfunction. Cell to cell communication and organ crosstalk is not only dependent on the free circulating markers, but may be more precisely modulated by extracellular vesicles (EV) such as exosomes and microvesicles, which contain protein markers along with RNA and DNA components in a defined structure. The composition of these vesicles along with variation in their size and amount could be another important puzzle piece to understand the pathophysiology of sepsis. Hypothesis: We aimed to examine variations size distribution of extracellular vesicles in patients with sepsis at time of their presentation and compare these with healthy controls healthy controls. Methods: Blood plasma samples were obtained from 10 patients at the time of presentation to the emergency department and 6 healthy control, after informed consent (HFHS IRB 1578, IRB 11000). Plasma was immediately frozen and stored at -80°C. For EV extraction samples were defrosted once and Invitrogen™ Total Exosome Extraction kit (from plasma) was used, according to manufactures protocol. EV pellets were re-suspended in PBS. Nanoparticle tracking analysis (NTA, NanoSight NS 300) was done at a standard dilution of 1:5.000. Western blots (ALIX, CD63, CD9, HSP70) and electron microscopy was conducted to confirm presence of EVs. Results: The average size of extracellular vesicles on NTA for patients with sepsis was 82.3 ± 106.5 nm and for healthy controls 71.3 ± 30.8 nm, p = 0.03. The average size of extracellular vesicles was 79.6 ± 152.1 nm for sepsis survivors (N = 6), 86.5 ± 28.3 for sepsis nonsurvivors (N = 4) and 71.3 ± 30.8 nm for healthy controls, p = 0.05. There was no statistical difference in the particle size between sepsis survivors and sepsis non-survivors. Conclusion: Size of extracellular vesicles in patients with sepsis at the time of presentation to the emergency department differs from the size of extracellular vesicles in healthy volunteers. Outlook: Differences in extracellular vesicle size at the time of presentation potentially indicate increased cellular processes and may be used in the future to aid diagnosis of sepsis.
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