Effects of <i>Enterococcus faecium</i> Extracellular Vesicles on Intestinal Barrier Function and Microbiota in Piglets

<i>Enterococcus faecium</i> (Ef) is a common microorganism in the gastrointestinal tract, recognized for its beneficial effects on human and animal health. It plays a vital role in promoting intestinal microbial balance and enhancing gut barrier function. A key feature of Ef extracellular vesicles (EfEVs) is their ability to specifically target sites within the intestine, leading us to hypothesize that EfEVs function as an important active component of Ef in intestinal microenvironment regulation. This study aimed to explore the impact of EfEV supplementation on the intestinal barrier function and microbiota composition in piglets. <i>In vitro</i> intestinal porcine epithelial cell J2 (IPEC-J2) cell culture experiments have shown that supplementation with EfEV significantly enhanced cell viability, increased the activity of the antioxidant enzyme, promoted cell proliferation, and inhibited autophagy. <i>In vitro,</i> fecal culture experiments demonstrated significant increases in OD630 and the contents of acetic aid, butyric acid, and isovaleric acid, and decreases in valeric acid following EfEV supplementation. Furthermore, EfEV supplementation altered the diversity and composition of the intestinal microbiota. It significantly reduced levels of <i>Escherichia-Shigella</i> at the family level, while increasing the abundance of beneficial microorganisms, including <i>[Eubacterium]_eligens_group</i>, <i>unidentified_Mitochondria</i>, <i>Lachnoclostridium</i>. In conclusion, EfEV plays a pivotal role in inhibiting pathogens growth, enhancing the production of metabolites such as acetic acid and butyrate acid, providing energy for microorganisms, and protecting the intestinal barrier.