Recent advances in understanding the role of extracellular vesicles from probiotics in intestinal immunity signaling

The diverse functions of gut symbiotic bacteria are attracting attention for their potential as probiotics. Some of those bacteria release extracellular vesicles (EVs), spherical structures of approximately 20-400 nm in diameter, outside their cell bodies. Recent research has significantly advanced our understanding of the physicochemical and biochemical properties, functions, and host-cell interactions of EVs released by probiotic bacteria used in food fermentation, such as lactic acid bacteria, bifidobacteria, butyric acid bacteria, and acetic acid bacteria. However, concerns have been raised regarding the use of these EVs as postbiotics. In this review, we discuss the newly discovered roles of EVs in the gut immune signaling and the challenges associated with their application as postbiotics.