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

Abstract

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. β-glucan has manifested of multiple biological effects including anti-inflammatory, regulating gut microbiota and immunomodulatory activities. At present, there is no relevant study considering the effects of β-glucan on NEC. This study aimed to investigate the effects of β-glucan on NEC. Methods Neonatal C57BL/6 mice were randomly divided into three groups: control group, NEC group and β-glucan group. Newborn 3-day-old mice were gavage with either 1mg/ml β-glucan or PBS at 0.03 ml/g for consecutive 7 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-hour modeling. HE staining was performed to assess the pathological injury of the intestine. The mRNA expression levels of inflammatory factors in intestinal tissues were determined by quantitative real-time PCR. The protein levels of TLR4, NF-κB and tight junctions proteins in intestinal tissues were evaluated using western blotting and immunohistochemistry. 16S rRNA sequencing was performed to determine the structure of gut microbiota. Results β-glucan administration ameliorated intestinal injury of NEC mice; reduced the intestinal expression of TLR4, NF-κB, interleukin- (IL-) 1β, IL-6 and TNF-α; and increased the intestinal expression of IL-10 (P < 0.05); improved the expression of ZO-1, Occludin and Claudin-1 within intestinal barrier. Pre-treatment with β-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 β-glucan intervention can prevent necrotizing enterocolitis in neonatal mice, possibly by suppressing TLR4-NF-κB signaling pathway, improving intestinal barrier function and partially regulating intestinal microbiota.