Bovine Milk-Derived Extracellular Vesicles Attenuate Liver Injury by Modulating the Gut–Liver Axis via <i>Faecalibaculum</i> -Mediated SCFA Production

Chronic liver injury represents a core pathological substrate in a spectrum of hepatic disorders, wherein gut-liver axis homeostasis critically drives progression. Although bovine milk extracellular vesicles (mEVs) positively regulate intestinal homeostasis, the mechanisms underlying their gut microbiota-linked hepatoprotection remain unclear. Herein, we demonstrated that mEVs (0.6 mg/kg/d) effectively alleviated carbon tetrachloride (CCl₄, 1 mg/kg)-induced liver injury, as evidenced by reduced hepatic inflammation and fibrosis. Concurrently, mEVs also markedly attenuated colonic barrier disruption and inflammation concomitant with liver injury. Gut microbiota analysis revealed that mEVs notably enriched the relative abundances of <i>Faecalibaculum</i> and <i>Lactobacillus</i>, which correlated positively with mEV-enhanced colonic short-chain fatty acid (SCFA)/free fatty acid receptor (FFAR) signaling. Furthermore, a causal link between the mEV-reshaped gut microbiota and the resulting hepatoprotection was further established via fecal microbiota transplantation (FMT). In summary, these findings revealed that mEVs attenuated liver injury in a gut microbiota-dependent manner, offering valuable insights into microbiota-targeted and mEV-based therapeutic strategies for hepatic disorders.