Fructophilic Apilactobacillus kunkeei alleviates high-fructose diet-induced lipid accumulation by modulating gut microbiota and intestinal barrier function in mice.

Excessive fructose consumption is strongly linked to metabolic syndrome, with gut microbiota playing a pivotal role in mediating fructose metabolism and associated metabolic disturbances. In this study, we aimed to characterize Apilactobacillus (A.) kunkeei, a fructophilic lactic acid bacterium from honey, and evaluate its probiotic function in male C57BL/6 J mice fed a high-fructose diet (HFD). Transcriptome analysis was carried out to analyze the activation of pathways under various culture conditions. Pathway inhibitors were used in cell culture and a hepatectomy mouse model to study the function of different pathways in hepatocyte growth and liver regeneration. Our results showed that A. kunkeei FM01 exhibited strong tolerance to simulated gastrointestinal stress in vitro, indicating good probiotic potential. Administration of A. kunkeei FM01 significantly reduced body weight gain, improved glucose tolerance, and attenuated hepatic and visceral (perirenal and epididymal) lipid accumulation in HFD-fed mice. Serum lipid profiling and targeted lipidomic analysis revealed that A. kunkeei FM01 lowered triglycerides, phosphatidylcholine, and lysophosphatidylcholine levels while increasing beneficial phospholipids such as phosphatidylethanolamine. Metagenomic analysis demonstrated that A. kunkeei FM01 modulated gut microbiota composition by reducing pro-inflammatory and fructose-metabolizing taxa, including Alistipes, Oscillibacter, Desulfovibrio, Lawsonibacter, and Enterococcus, while enriching beneficial species, including Kineothrix alysoides and Faecalibaculum rodentium. These microbial shifts were associated with increased abundances in genes encoding carbohydrate-active enzymes and amino acid biosynthesis pathways. Furthermore, A. kunkeei FM01 restored intestinal barrier integrity by upregulating tight junction proteins (Zonula Occludens-1 and occludin) and reduced serum lipopolysaccharide and diamine oxidase levels. Collectively, these findings suggest that A. kunkeei FM01 exerts protective effects against HFD-induced metabolic dysfunction through multi-targeted mechanisms involving lipid metabolism, gut microbiota modulation, and intestinal barrier restoration. This study identifies A. kunkeei FM01 as a promising probiotic candidate for preventing and managing fructose-associated metabolic disorders.