Abstract
Over the last 20 years, extracellular vesicles (EVs) have been established as an additional way to transmit signals outside the cell. They are membrane-surrounded structures of nanometric size that can either originate from the membrane invagination of multivesicular bodies of the late endosomal compartment (exosomes) or bud from the plasma membrane (microvesicles). They contain proteins, lipids, and nucleic acids—namely miRNA, but also mRNA and lncRNA—which are derived from the parental cell, and have been retrieved in every fluid of the body. As carriers of antigens, either alone or in association with major histocompatibility complex (MHC) class II and class I molecules, their immunomodulatory properties have been extensively investigated. Moreover, recent studies have shown that EVs may carry and deliver membrane-derived bioactive lipids that play an important function in the immune system and related pathologies, such as prostaglandins, leukotrienes, specialized pro-resolving mediators, and lysophospholipids. EVs protect bioactive lipids from degradation and play a role in the transcellular synthesis of prostaglandins and leukotrienes. Here, we summarized the role of EVs in the regulation of immune response, specifically focusing our attention on the emerging role of EVs as carriers of bioactive lipids, which is important for immune system function.
Highlights
IntroductionCell-to-cell communication may take place through several mechanisms
In multicellular organisms, cell-to-cell communication may take place through several mechanisms
This study showed that enterobacteria-secreted particles induce the production of exosome-like S1P-containing particles by intestinal epithelium, and that these extracellular vesicles (EVs) drive tumorigenesis in a Th17-dependent manner, possibly interfering with the recruitment of neutrophils and macrophages to altered and/or inhibiting T regulatory cells (Tregs)
Summary
Cell-to-cell communication may take place through several mechanisms. Microvesicles, which are referred to as ectosomes, originate from plasma membrane outward budding They are characterized by a wider size distribution (from 100 to 1000 nm) and a less regular morphology than exosomes. Apoptotic bodies are released by dying cells during the later stages of apoptosis [3] They have a larger size (500–5000 nm) than exosomes and microvesicles, a few studies reported that apoptotic cells may release smaller vesicles [4]. EVs carry, in their inner core or in their lipid bilayer, bioactive compounds such as proteins, lipids, nucleic acids, and metabolites Most of these molecules are structural components, but they are signalling mediators. They have been exploited either to break the tolerance against tumor antigens in anti-cancer immunotherapy, or as immunosuppressive agents in inflammation-driven immune pathologies, namely autoimmune diseases [22]
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