W/O Emulsion Encapsulated Oligopeptide (KRQKYD) for Ameliorating Alcohol-induced Liver Damage by Regulating the Intestinal Homeostasis

Alcohol-induced liver damage (ALD) remains a global health burden with limited therapeutic options. To address this challenge, this study developed a water-in-oil (W/O) emulsion encapsulating the oligopeptide KRQKYD, using Jinhua ham fat (JHF) as the oil phase, aiming to enhance the oligopeptide’s digestive stability and ameliorate ALD by regulating intestinal homeostasis. The results confirmed that the W/O emulsion (containing 60% oligopeptide solution) had high encapsulation efficiency (96.37% ± 9.43%), which significantly enhanced the gastrointestinal digestion stability of KRQKYD—with 86.48% ± 2.20% of KRQKYD retained after 120 minutes of simulated intestinal digestion, a rate markedly higher than the 60.84% ± 1.84% retention of free KRQKYD. Moreover, in C57BL/6 mouse models of ALD, oral administration of the emulsion (400 mg/kg B.W., containing 60% oligopeptide solution at 55.6% w/w) significantly reduced serum levels of alanine transaminase (ALT), aspartate transaminase (AST), and malondialdehyde (MDA) compared to ethanol-treated mice (P < 0.05), with efficacy superior to that of KRQKYD or JHF alone. Mechanistically, the emulsion exerted multifaceted protective effects through synergistic actions of its components: KRQKYD promoted the proliferation of Akkermansia muciniphila by alleviating intestinal oxidative stress, while JHF enriched Lactobacillus by replenishing long-chain fatty acids, collectively restoring microbial balance (e.g., reducing Proteobacteria and increasing Verrucomicrobia). Concurrently, KRQKYD upregulated the NRF2/HO-1 pathway, and JHF activated the AhR/NQO1 pathway, which together reduced hepatic ROS accumulation and enhanced the activities of SOD and GSH-Px. Additionally, the emulsion strengthened intestinal barrier function by increasing Occludin and Claudin-1 expression, thereby reducing LPS leakage; this, in turn, inhibited the LPS-TLR4-NF-κB cascade and lowered hepatic levels of pro-inflammatory cytokines (TNF-α, IL-1β, IL-6). Furthermore, in terms of lipid metabolism, the emulsion downregulated SREBP1c-mediated lipid synthesis and activated AMPK-dependent lipid oxidation, ultimately decreasing hepatic triglyceride accumulation. This study demonstrates that the W/O emulsion enhances KRQKYD stability and exerts synergistic effects with JHF, providing a novel strategy for the oral delivery of bioactive oligopeptides to ameliorate ALD by targeting gut-liver crosstalk.