β-glucan protects against necrotizing enterocolitis in mice by inhibiting intestinal inflammation, improving the gut barrier, and modulating gut microbiota

Background Necrotizing enterocolitis (NEC) is a devastating gastrointestinal disease with high morbidity and mortality, affecting preterm infants especially those with very low and extremely low birth weight. beta-glucan has manifested multiple biological effects including anti-inflammatory, regulation of gut microbiota, and immunomodulatory activities. This study aimed to investigate the effects of beta-glucan on NEC.Methods Neonatal C57BL/6 mice were randomly divided into three groups: Control group, NEC group and beta-glucan group. Newborn 3-day-old mice were gavaged with either 1 mg/ml beta-glucan or phosphate buffer saline at 0.03 ml/g for 7 consecutive days before NEC induction and a NEC model was established with hypoxia combined with cold exposure and formula feeding. All the pups were killed after 72-h modeling. Hematoxylin-eosin staining was performed to assess the pathological injury to the intestines. The mRNA expression levels of inflammatory factors in intestinal tissues were determined using quantitative real-time PCR. The protein levels of TLR4, NF-kappa B and tight junction proteins in intestinal tissues were evaluated using western blotting and immunohistochemistry. 16S rRNA sequencing was performed to determine the structure of the gut microbiota.Results beta-glucan administration ameliorated intestinal injury of NEC mice; reduced the intestinal expression of TLR4, NF-kappa B, IL-1 beta, IL-6, and TNF-alpha; increased the intestinal expression of IL-10; and improved the expression of ZO-1, Occludin and Claudin-1 within the intestinal barrier. Pre-treatment with beta-glucan also increased the proportion of Actinobacteria, Clostridium butyricum, Lactobacillus johnsonii, Lactobacillus murinus, and Lachnospiraceae bacterium mt14 and reduced the proportion of Klebsiella oxytoca g Klebsiella in the NEC model.Conclusion beta-glucan intervention prevents against NEC in neonatal mice, possibly by suppressing the TLR4-NF-kappa B signaling pathway, improving intestinal barrier function, and partially regulating intestinal microbiota.