Extracellular Vesicles from Lactic Acid Bacteria: Emerging Postbiotic Effectors in Host-Microbe Crosstalk.

Abstract

This article addresses extracellular vesicles derived from lactic acid bacteria (LAB-EVs), which have become fundamental mediators of host-microbe communication, yielding new insights about the molecular mechanisms underlying probiotic and postbiotic activity. The review integrates current evidence on the biogenesis, structural characteristics, and functional roles of LAB-EVs, stressing their capacity to transport bioactive cargos - including proteins, nucleic acids, and metabolites - to host cells. We highlight how LAB-EVs interact with the intestinal epithelial barrier, modulate innate and adaptive immune responses, and contribute to the maintenance of mucosal homeostasis. Particular attention is given to signaling pathways mediated by pattern recognition receptors, macrophage polarization, and the regulation of tight junction proteins, which collectively sustain barrier integrity and immune tolerance. Furthermore, we discuss the therapeutic implications of LAB-EVs in inflammatory bowel disease, epithelial repair, and systemic tissue regeneration. Despite these promising findings, significant obstacles remain in standardizing isolation methods, characterizing vesicle heterogeneity, and developing regulatory systems for clinical translation. Conquering these technical and safety barriers will be essential to consolidate LAB-EVs as safe and effective postbiotic tools in microbiome-based therapies. This review provides a discerning perspective on the current state of LAB-EVs research and describes future directions for their use in human health.