Probiotic Pediococcus pentosaceus NQ0729 Attenuates ETEC-Induced Rumen Epithelial Injury in Yak Calves.

Abstract

Enterotoxigenic Escherichia coli (ETEC) infection is an important cause of gastrointestinal injury in young animals. However, whether probiotic strains isolated from naturally fermented yak yogurt can protect rumen epithelial health in ETEC-challenged yak calves remains unclear. This study investigated the effects of Pediococcus pentosaceus NQ0729 isolated from naturally fermented yak yogurt on ETEC-induced rumen epithelial injury and explored its associations with the rumen microbiota and microbiota-associated metabolites. ETEC challenge increased the serum IL-1β, IL-6, TNF-α, IFN-γ, MDA, and ROS levels and decreased the IL-10, SOD, CAT, GSH-Px, and T-AOC levels (P < 0.05). P. pentosaceus NQ0729 pretreatment attenuated these inflammatory and oxidative stress responses (P < 0.05). ETEC challenge also caused rumen epithelial morphological damage, increased epithelial apoptosis, and reduced the expression of epithelial barrier-related markers, including ZO-1, Occludin, and Claudin-4, as well as the mucin-related marker MUC2 (P < 0.05). These alterations were partially attenuated by P. pentosaceus NQ0729 pretreatment (P < 0.05). In addition, P. pentosaceus NQ0729 reduced the activation of TLR4/MyD88/NF-κB-related inflammatory signaling and enhanced Nrf2-associated antioxidant defense in rumen tissues (P < 0.05). 16 S rRNA gene sequencing and untargeted metabolomics revealed that P. pentosaceus NQ0729 altered the rumen microbial composition and ruminal metabolite profile. Integrated analysis further revealed significant associations among differential rumen genera, microbiota-associated metabolites, and host inflammatory, oxidative stress, antioxidant, and barrier-related indices (P < 0.05). P. pentosaceus NQ0729 alleviated ETEC-induced rumen epithelial injury in yak calves, which was accompanied by reduced inflammation and oxidative stress, improved epithelial barrier-related markers, and changes in the rumen microbiota and microbiota-associated metabolites. These findings suggest that P. pentosaceus NQ0729 may protect rumen epithelial homeostasis, with its protective effects accompanied by changes in the rumen microbiota and microbiota-associated metabolites and by significant associations among microbial, metabolic, and host barrier-related features.

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