Extracellular Vesicles of Probiotics: From Structural and Functional Characteristics to Practical Application

The beneficial properties of probiotic bacteria are well known. It has recently been established that these properties are largely due to extracellular vesicles (EVs). EVs produced by bacterial cells transport a wide range of compounds (proteins, lipids, polysaccharides, metabolites, DNA, RNA, including small RNA). The specifics of the physical and chemical properties and composition of EVs determine the characteristics of their biological activity. EVs are enriched with bioactive molecules that can mediate the modulation of signaling pathways and reprogramming of target cells. The size (20–300 nm), biocompatibility, and ability to deliver drugs to different organs and tissues make EVs of probiotics a promising tool for practical application in medicine. Experimental data obtained in recent years have revealed the great potential of probiotic EVs for immunocorrection, the treatment of a number of skin diseases, digestive disorders, metabolic, and psychoneurological disorders, as well as oncological diseases. This has determined the rapid growth of interest in probiotic EVs as postbiotics, fundamentally new drugs and their delivery vehicles, new types of vaccines, and tools for cancer therapy. The realization of emerging prospects requires the comprehensive structural and functional characterization of probiotic EVs. This review presents an analysis of publications devoted to the characterization of probiotic EVs from the point of view of problems and prospects for fundamental research and the practical application of these nanostructures, the development of new scientific directions, and the development of a biosafety system.