Extracellular Vesicles as Immunomodulatory Mediators in Inflammatory Processes

Extracellular vesicles (EVs) is the collective term used for cell-secreted phospholipid bilayer-bound structures generated by an evolutionarily conserved process. EVs include microvesicles, apoptotic bodies, and exosomes. These three EVs subtypes are basically classified based on their biogenesis and diameter range and can be secreted by all cell types tested so far. EVs are of particular interest in biology because their origin involves a distinct intracellular regulatory process that likely determines their composition, and their function(s) once released into the extracellular space. They can carry many constituents including DNA, RNA, lipids, metabolites, and cytosolic and cell-surface proteins, and have been described to play important roles in regulating cell signaling and cell–to-cell communication. EVs play a complex role in immune system, influencing both innate and adaptive immune responses through the exchange of EVs among immune cells as macrophages, dendritic cells, B cells, T cells, and others. Considered as protectors of complex biological information, EVs immunomodulatory functions can contributes to the initiation, propagation and regulation of inflammatory diseases. Previous research indicates that EVs have been implicated in some pathogenic processes as formation of immune complexes, antigen presentation, delivery of miRNAs, inflammatory cytokines, proteases, and other proteins. It is also well recognized that EVs contents are altered depending on the local microenvironment, supporting the possibility of their use as biomarkers due to their stability in body fluids. In contrast to their role in the pathogenesis of inflammatory conditions, EVs by themselves or as delivery vehicles have been explored as therapeutic agents. Dendritic cells and mesenchymal stem cells (MSC)-derived exosomes have been demonstrated to exert immunoregulatory and immunosuppressive effects, for example through the suppression of T cell proliferation, generation of regulatory T cells and miRNA delivery.

The aim of this Research Topic is to provide comprehensive overview of how EVs affect the inflammatory processes. The knowledge of the complex biology of EVs remains incomplete and it requires further comprehensive studies on the mechanisms by which they modulate the immune response. We still have a lot to learn about EVs role in pathogenesis, and future work has the potential to elicit new therapeutic approaches to target the diseases, and its interfaces.

This Research Topic welcomes researchers to submit Original Research, Reviews, Mini-Reviews, and Methods articles that address, but are not limited to, the following topics:

• Mechanisms underlying the immunoregulatory functions of EVs from both immune cells and non-immune cells.
• Signaling properties of EVs and their role in cell-to-cell communication.
• Novel methods and concepts for studying EVs in immune regulation.
• Physiological and pathological functions of EVs in inflammatory disorders, and their potential as diagnostic and therapeutic tools.
• Possible roles of EVs in mediating both natural and therapeutic tolerance.