3-Fucosyllactose and 3'-sialyllactose combined with Lacticaseibacillus rhamnosus 1.0320 alleviate necrotizing enterocolitis by modulating the gut microbiota and regulating NF-κB/Nrf2 pathways.

Necrotizing enterocolitis (NEC) is a severe gastrointestinal disease that primarily affects premature infants. In recent years, increasing attention has been paid to the potential roles of human milk oligosaccharides (HMOs) and probiotics in the prevention and treatment of NEC. In this study, a neonatal rat NEC model was established to evaluate the protective effects of Lacticaseibacillus rhamnosus 1.0320 combined with 3-FL and 3'-SL. The results demonstrated that 1.0320FS improved the macroscopic manifestations of NEC, reduced clinical disease scores, and improved histopathological alterations. Moreover, 1.0320FS modulated intestinal inflammatory responses by inhibiting the NF-κB signaling pathway and reducing the levels of pro-inflammatory cytokines. Meanwhile, it activated the Nrf2/NQO1 antioxidant pathway, increased the activities of GSH, SOD, and CAT, reduced MDA levels, and alleviated oxidative stress-induced intestinal damage. In addition, 1.0320FS promoted the expression of tight junction proteins, thereby restoring intestinal barrier integrity. The combined intervention also reshaped gut microbiota composition, characterized by an increased abundance of Firmicutes and a decreased abundance of Proteobacteria, enrichment of beneficial bacteria such as Lactobacillus, and suppression of harmful bacteria including Proteus. Furthermore, short-chain fatty acid (SCFA) levels were significantly elevated. In summary, L. rhamnosus 1.0320 combined with 3-FL and 3'-SL alleviated intestinal injury in NEC through multiple mechanisms, including regulation of inflammation, oxidative stress, intestinal barrier function, immune balance, and gut microbiota homeostasis.