Kefir is a traditional fermented dairy beverage rich in lactic acid bacteria (LAB) with probiotic potential. Extracellular vesicles (EVs) produced by LAB carry diverse bioactive components and play key roles in inter-strain communication and functional regulation. However, the roles and mechanisms of microbial EVs in fermented foods remain to be systematically elucidated. Here, we characterized the proteomic features and anti-inflammatory effects of EVs from kefir-derived LAB-Lentilactobacillus kefiri KLK29 (KLK29EVs) and Enterococcus faecium KEF14 (KEF14EVs). The two EV proteomes were dominated by cytosol-associated proteins and were enriched in functional modules related to carbohydrate metabolism, transmembrane transport, signal transduction, and environmental response. Several proteins were associated with inflammation regulation. At non-cytotoxic doses (KLK29EVs, 5 μg/mL; KEF14EVs, 1 μg/mL), both EV preparations downregulated pro-inflammatory cytokines, upregulated anti-inflammatory cytokines, and suppressed NF-κB activation. This study provides important information on the functions and mechanistic insights of fermented-food-derived LAB EVs and offers a theoretical basis for their potential application in functional food development.
Li et al. (2026) studied this question.