The carrying pigeons of the cell: exosomes and their role in infectious diseases caused by human pathogens

Exosomes have recently been classified as the newest family members of 'bioactive vesicles' that function to promote intercellular communication. Long ignored and thought to be only a mechanism by which cellular waste is removed, exosomes have garnered a huge amount of interest in recent years as their critical functions in maintaining homeostasis through intercellular communication and also in different types of diseases have been demonstrated. Many groundbreaking studies of exosome functions have been performed in the cancer field and the infectious disease areas of study, revealing the importance and also the fascinating complexity of exosomal packaging, targeting, and functions. Selective packaging of exosomes in response to the type of infection, exosomal modulation of the immune response and host signaling pathways, exosomal regulation of pathogen spread, and effects of exosomes on the degree of pathogenesis have all been well documented. In this review, we provide a synthesis of the current understanding of the role of exosomes during infections caused by human pathogens and discuss the implications of these findings for a better understanding of pathogenic mechanisms and future therapeutic and diagnostic applications.