With the development of technology, more and more strategies were continually applied for detecting and isolating exosomes, promoting the exploration of exosomes. Due to the complexity of endocytic pathways, the mechanisms regulating exosome release have not been well elucidated to date. For instance, proteins of the endosomal sorting complex required for transport (ESCRT) and CD63 are associated with MVBs and have also been found in exosomes ( 10).
Therefore, the composition of exosomes is expected to reflect to some extent the composition of MVBs. Another possibility is for MVBs to merge with the plasma membrane, therefore, releasing its ILVs into the extracellular space, where they are called exosomes ( 9). The main fate of MVBs is to fuse with lysosomes, where their content is degraded. Early endosomes mature into late endosomes characterized by the presence of ILVs in their lumen, reason for which they are also called MVBs ( 7, 8). Endocytic vesicles then fuse with early endosomes and deliver their content to them. At the same time, we elaborate on the role of exosomes in immune regulation.Īccording to present knowledge, the biogenesis of an exosome consists of four stages: initiation, endocytosis, MVB formation, and secretion ( 6).Īt first, membrane-associated molecules, such as nucleic acids, proteins and others, are internalized via endocytic vesicles formed by invagination of the plasma membrane. We discuss two opposite aspects: infection and anti-infection, and we hypothesize a balance between them. The purpose of this review is to describe present findings regarding exosomes and pathogen infections, and highlight their enormous potential in clinical diagnosis and treatment. We believe that exosomes act as “bridges” during pathogen infections through the mechanisms mentioned above. Second, exosomes play anti-infection roles through: (1) inhibiting pathogen proliferation and infection directly (2) inducing immune responses such as those related to the function of monocyte-macrophages, NK cells, T cells, and B cells. First, exosomes containing proteins and RNAs derived from pathogens can promote infections in three ways: (1) mediating further infection by transmitting pathogen-related molecules (2) participating in the immune escape of pathogens and (3) inhibiting immune responses by favoring immune cell apoptosis. Our view is that exosomes exert a bidirectional regulatory effect on pathogen infections by delivering their content. Consequently, they play an important role in health and disease. They are composed of proteins, lipids, and RNAs through which they participate in cellular crosstalk. Exosomes are extracellular vesicles derived from cell endocytosis which act as transmitters between cells.