Exosomes are small subtypes of extracellular vesicles (EVs) naturally released by different types of cells into their environment. Their physiological roles appear to be multiple, yet many aspects of their biological activities remain to be understood. These vesicles can transport and deliver a variety of cargoes and may serve as unconventional secretory vesicles. Thus, they play a crucial role as important vectors for intercellular communication and the maintenance of homeostasis. Exosome production and content can vary under several stresses or modifications in the cell microenvironment, influencing cellular responses and stimulating immunity. During infectious processes, exosomes are described as double-edged swords, displaying both beneficial and detrimental effects. Owing to their tractability, the analysis of EVs from multiple biofluids has become a booming tool for monitoring various pathologies, from infectious to cancerous origins. In this review, we present an overview of exosome features and discuss their particular and ambiguous functions in infectious contexts. We then focus on their properties as diagnostic or therapeutic tools. In this regard, we explore the capacity of exosomes to vectorize immunogenic viral antigens and their function in mounting adaptive immune responses. As exosomes provide interesting platforms for antigen presentation, we further review the available data on exosome engineering, which enables peptides of interest to be exposed at their surface. In the light of all these data, exosomes are emerging as promising avenues for vaccine strategies.

Exosomes are small subtypes of extracellular vesicles (EVs) naturally released by different types of cells into their environment. Their physiological roles appear to be multiple, and many aspects of their biological activities remain to be understood. These vesicles can transport and deliver a variety of cargoes, including proteins, metabolites, nucleic acids, and lipids. Consequently, it is argued that exosomes may serve as unconventional secretory vesicles, playing a crucial role as important vectors for intercellular communication and the maintenance of homeostasis. Exosome production and content can vary under several stresses or modifications in the cell microenvironment, influencing cellular responses both qualitatively and quantitatively. Thus, the analysis of EVs from multiple biofluids, due to its ease of implementation, has become a booming tool for monitoring various pathologies, particularly cancer, as we shall outline further on. During infectious processes, exosomes are described as double-edged swords, displaying both beneficial and detrimental effects. Indeed, during a viral infection, the production of EVs and circulating exosomes is often enhanced to signal danger, stimulate immunity, and possibly serve as pathological biomarkers. Conversely, viruses can disrupt or hijack the exosome content and production. In this review, we discuss the particular and ambiguous functions of exosomes in infectious contexts. Furthermore, we explore the vectoring capacity of exosomes in light of the extensive literature examining their function in mounting adaptive immune responses. Exosomes provide an interesting platform for antigen presentation and could therefore serve as novel therapeutic targets or be used in vaccine strategies.

Médecine/sciences (M/S), revue internationale dans le domaine de la recherche biologique, médicale et en santé

Les vésicules extracellulaires participent à la communication intercellulaire. Dans une tumeur, elles sont souvent associées au développement de métastases ou à l’immunosuppression. Les virus oncolytiques sont des virus réplicatifs atténués qui infectent les cellules tumorales. Ils induisent une mort cellulaire immunogène qui active une réponse immunitaire antitumorale. Ces virus peuvent aussi servir de vecteurs pour exprimer des molécules thérapeutiques dans la tumeur. A ce jour, l’effet des virus oncolytiques sur la sécrétion des vésicules extracellulaires tumorales est peu connu. L’objectif de ce travail était de caractériser l’effet du virus de la stomatite vésiculaire et du virus de la vaccine sur les vésicules extracellulaires sécrétées par des cellules de mélanome ou de cancers thoraciques humains. Nos résultats montrent que les cellules infectées sécrètent davantage de vésicules extracellulaires. Ces vésicules contiennent des protéines virales qui augmentent le transfert de leur contenu à des cellules souvent présentes dans le microenvironnement tumoral. Leur contenu est enrichi en protéines liées à l’immunité et l’incubation de lymphocytes T CD8 avec des vésicules de cellules infectées a permis d’augmenter leurs fonctions cytotoxiques. Nos résultats suggèrent que les virus oncolytiques augmentent la communication médiée par les vésicules extracellulaires, ce qui participe à l’activation d’une réponse immunitaire antitumorale. Ce mécanisme pourrait expliquer une partie de l’effet thérapeutique des virus oncolytiques.