Extracellular vesicles have emerged as important elements in cell-cell communication and as key players in disease pathogenesis via surface contact but also via transmission of their cargo between different cells. During the last decade, various techniques have been used to investigate the relative differences in biophysical and biomolecular properties of different population of extracellular vesicles.
In this research, we have used various vibrational spectroscopic techniques including attenuated total reflectance (bio-ATR) and atomic force microscope infrared (AFM-IR) spectroscopies to assess biochemical changes in the heterogeneous population of bulk and individual extracellular vesicles derived from LPS-stimulated monocytes, as a model of septic shock. In addition to being relatively quick, one of the great advantages of vibrational spectroscopic techniques compared to the traditional semi-quantitative omics approaches, is their ability to provide information on relative changes between classes (proteins, lipids, nucleic acids, carbohydrates) and protein conformations.
Sepsis is a life-threatening condition that arises from a systemic inflammatory response to infection. Increased numbers of extracellular vesicles have been reported in different pathological disorders including severely septic patients with renal dysfunction, meningococcal infection, and Candida infection.
In this study we not only have compared two different vibrational spectroscopic techniques to analyse bulk and individual extracellular vesicles but also have demonstrated time-dependent changes in biomolecular content of extracellular vesicles derived from monocytes activated with lipopolysaccharide, interleukin-4 or interferon-gamma. These results provide pivotal insights into the mechanisms of extracellular vesicle production, as well as on their role in physiological and pathological pathways.