Extracellular vesicles and their content in bioactive lipid mediators

Extracellular vesicles (EVs), such as exosomes and microvesicles, are small membrane-bound vesicles released by cells under various conditions. In a multitude of physiological and pathological conditions, EVs contribute to intercellular communication by facilitating exchange of material between cells. Rapidly growing interest is aimed at better understanding EV function and their use as biomarkers. The vast EV cargo includes cytokines, growth factors, organelles, nucleic acids (messenger and micro RNA), and transcription factors. A large proportion of research dedicated to EVs is focused on their microRNA cargo; however, much less is known about other EV constituents, in particular eicosanoids. These potent bioactive lipid mediators, derived from arachidonic acid, are shuttled in EVs along with the enzymes in charge of their synthesis. In the extracellular milieu, EVs also interact with secreted phospholipases to generate eicosanoids, which then regulate the transfer of cargo into a cellular recipient. Eicosanoids are useful as biomarkers and contribute to a variety of biological functions, including modulation of distal immune responses. Here, researchers from the Université Laval discuss the reported roles of eicosanoids conveyed by EVs and describe their potential as biomarker.

Eicosanoids and the associated enzymes are comprised in extracellular vesicles

Cells produce different types of extracellular vesicles (EV), such as exosomes, and microvesicles.Exosomes are stored in multivesicluar bodies (MVB) and released on cell activation whereas microvesicles are generated by plasma membrane budding and shedding.Graphic  representation  of  the  metabolism  of  AA  into  eicosanoids.  AA; arachidonic    acid,    Cox-1;    cyclooxygenase-1,    Cox-2;    cyclooxygenase-2,    TxS; thromboxane    synthase,    12-LO;    12-lipoxygenase,    5-LO;    5-lipoxygenase,    LT; leukotriene, PG; prostaglandin, HETE; hydroxyeicosatetraenoic acid.