About this Research Topic
Cell-to-cell communication is critical for maintaining homeostasis and responding quickly to environmental stimuli. Besides direct intercellular contact, this communication is often mediated by soluble factors that can convey signals to a large repertoire of responding cells, either locally or remotely. Extracellular vesicles (EVs) are membrane-enveloped vesicles of different sizes in the nanometer-level range and are naturally released from almost all mammalian cells. They ferry various biological cargos including proteins, multiple RNA species, and DNAs, and transfer these potential functional mediators to neighboring and distant recipient cells. Except for apoptotic bodies (a separate class of EVs), EVs are broadly classified into two categories, exosomes and microvesicles, owing to their endocytic or plasma membrane origin. Exosomes and microvesicles are also referred to as small and large EVs, respectively, based on their distinct size ranges.
The formation of exosomes is initiated by budding into the late endosome; the multivesicular body transits toward and fuses with the plasma membrane before releasing intraluminal vesicles into the extracellular environment as exosomes. In contrast, microvesicles are generated at the plasma membrane by outward budding and expulsion of plasma membrane directly from the cell surface. In response to stimuli, the parent cell not only releases EVs, but more importantly, also sorts highly specific biological cargos into EVs, contributing to disease pathogenesis. Yet the underlying mechanism remains largely uninvestigated. EVs inherit cell-type surfaces from their parent cells due to the nature of the endogenous plasma membrane, resulting in different affinities for different recipient cell types. Mounting evidence suggests EVs derived from specific parent cells are preferentially captured by recipient cells of a specific type.
In the context of immune responses against pathogens, EVs can carry pathogen antigens and are known to evoke immune responses, thereby gaining interest as a potential vaccine delivery system. Several studies have harnessed EVs produced by bacteria derived from various strains for use as vaccinogens to induce adaptive immune responses. However, the human immune system recognizes bacterial EVs as foreign and bacterial EVs contain virulence factors on their surfaces, which pose a risk of provoking toxic adverse effects such as bacteria-induced sepsis. Therefore, EVs endogenously derived from host cells are regarded as the ideal “nature’s delivery system”.
Most enveloped virions are the same size as exosomes, and their budding shares many similarities with exosome biogenesis. Major exosomal surface markers CD63 and CD81 are enriched in some enveloped viruses. These similarities, both structurally and functionally, make the separation of virus-free EVs and virions in infected specimens particularly challenging.
This Research Topic aims to seek articles about new insights into the functional role of EVs derived from specific cell types following inflammation and infection, and discussion about how EVs may aid in the diagnosis and development of novel therapeutic strategies for infectious diseases. We welcome authors to contribute with Original Research, Reviews, Mini-Reviews, Perspective and Opinion articles, Protocols, Technology Reports, Clinical Trials, or Case Reports focusing on, but not limited to, the following points:
• Cell surface markers on EVs for identification of the parent cell type.
• Mechanism of specific cargo sorting into EVs in response to inflammatory or infectious stimuli.
• Characterization of the functional roles of EVs or EV cargos in recipient cells of a specific type.
• Therapeutic potential of EVs in the context of inflammation and pathogen infection.
• Bacteria-derived EVs as vaccinogens.
• Host-derived EVs as a novel vaccine delivery system.
• EVs and EV cargos as biomarkers of inflammation and infectious diseases.
• State-of-the-art methods for purification of virus-free EVs.
The formation of exosomes is initiated by budding into the late endosome; the multivesicular body transits toward and fuses with the plasma membrane before releasing intraluminal vesicles into the extracellular environment as exosomes. In contrast, microvesicles are generated at the plasma membrane by outward budding and expulsion of plasma membrane directly from the cell surface. In response to stimuli, the parent cell not only releases EVs, but more importantly, also sorts highly specific biological cargos into EVs, contributing to disease pathogenesis. Yet the underlying mechanism remains largely uninvestigated. EVs inherit cell-type surfaces from their parent cells due to the nature of the endogenous plasma membrane, resulting in different affinities for different recipient cell types. Mounting evidence suggests EVs derived from specific parent cells are preferentially captured by recipient cells of a specific type.
In the context of immune responses against pathogens, EVs can carry pathogen antigens and are known to evoke immune responses, thereby gaining interest as a potential vaccine delivery system. Several studies have harnessed EVs produced by bacteria derived from various strains for use as vaccinogens to induce adaptive immune responses. However, the human immune system recognizes bacterial EVs as foreign and bacterial EVs contain virulence factors on their surfaces, which pose a risk of provoking toxic adverse effects such as bacteria-induced sepsis. Therefore, EVs endogenously derived from host cells are regarded as the ideal “nature’s delivery system”.
Most enveloped virions are the same size as exosomes, and their budding shares many similarities with exosome biogenesis. Major exosomal surface markers CD63 and CD81 are enriched in some enveloped viruses. These similarities, both structurally and functionally, make the separation of virus-free EVs and virions in infected specimens particularly challenging.
This Research Topic aims to seek articles about new insights into the functional role of EVs derived from specific cell types following inflammation and infection, and discussion about how EVs may aid in the diagnosis and development of novel therapeutic strategies for infectious diseases. We welcome authors to contribute with Original Research, Reviews, Mini-Reviews, Perspective and Opinion articles, Protocols, Technology Reports, Clinical Trials, or Case Reports focusing on, but not limited to, the following points:
• Cell surface markers on EVs for identification of the parent cell type.
• Mechanism of specific cargo sorting into EVs in response to inflammatory or infectious stimuli.
• Characterization of the functional roles of EVs or EV cargos in recipient cells of a specific type.
• Therapeutic potential of EVs in the context of inflammation and pathogen infection.
• Bacteria-derived EVs as vaccinogens.
• Host-derived EVs as a novel vaccine delivery system.
• EVs and EV cargos as biomarkers of inflammation and infectious diseases.
• State-of-the-art methods for purification of virus-free EVs.
Important Note: All contributions to this Research Topic must be within the scope of the section and journal to which they are submitted, as defined in their mission statements. Frontiers reserves the right to guide an out-of-scope manuscript to a more suitable section or journal at any stage of peer review.
