Protective Effects of Biifdobacterium on intestinal tissue of newborn rats with necrotizing enterocolitis and its regulation / 中华围产医学杂志

ABSTRACT

Objective To discuss the possible molecular mechanisms involved in the protective effects of Biifdobacterium on intestinal tissue of necrotizing enterocolitis (NEC) newborn rats. Methods Seventy-five newborn Sprague-Dawley rats (born within 2 h) were randomly divided into five groups, each group with 15 rats. Group A was the NEC model group, and the rats were fed lipopolysaccharide (LPS) and formula. Group B was the Biifdobacterium treatment group, and the rats were fed LPS and formula and Biifdobacterium micro-capsule. Group C was the artificial feeding control group, and the rats were fed formula. Group D was the Biifdobacterium control group, and the rats were fed formula and Biifdobacterium micro-capsule. Group E was the breastfeeding control group, and the rats were fed rat breast milk by mothers. LPS 30 mg/kg was administered by gavage once per day for 3 days. Bifidobacterium micro-capsules were given as 1×1010 colony forming units/ml by gavage with formula once per day. After fed for 72 h and fasted for 12 h, the five groups of rats were killed by decapitation. Morphological changes in the terminal ileum tissue were observed under a light microscope and intestinal injury was scored. The expression of Toll-like receptor (TLR) 2, TLR4, and nuclear transcription factor (NF)-κB p65 was detected by immunohistochemical methods. Kruskal-Wallis test, analysis of variance, corrected Chi-square test and Fisher's exact test were used for statistics. Results The morbidity of NEC in group A to E was 11/15, 4/15, 3/15, 2/15 and 0/15, respectively;the intestinal injury score in group A to E was 3.37±0.27, 1.53±0.44, 1.75±0.37, 0.92±0.39 and 0.30±0.18, respectively; the expression level of TLR2 in group A to E was 0.35±0.05, 0.30±0.03, 0.32±0.04, 0.30±0.02 and 0.29±0.03, respectively;the expression level of TLR4 in group A to E was 0.48±0.05, 0.34±0.03, 0.36±0.03, 0.37±0.04 and 0.35±0.02, respectively;the expression level of NF-κB p65 in group A to E was 0.43±0.03, 0.29±0.03, 0.35±0.02, 0.32±0.02 and 0.30±0.02, respectively. The differences in NEC morbidity, intestinal injury score, and the expression levels of TLR4, TLR2 and NF-κB p65 among the five groups were all statistically significant (χ2, H or F=23.863, 70.290, 8.803, 38.599 and 75.076, respectively, all P 0.05). The intestinal injury score in the Bifidobacterium treatment group was significantly higher than that in the Bifidobacterium control group and the breastfeeding control group (both P 0.05). The expression levels of TLR4 and NF-κB p65 in the Biifdobacterium treatment group were significantly lower than those in the artificial feeding control group and the Biifdobacterium control group (all P 0.05). The expression level of TLR2 in the Biifdobacterium treatment group compared with the three control groups was not significantly different (all P > 0.05). Conclusions Biifdobacterium may inhibit pathogenic bacteria or regulate the negative feedback of TLR2 to reduce the expression of TLR2 and TLR4 in intestinal mucosa cells, inhibit the NF-κB pathway, attenuate the inflammatory reaction, and play a role in the prevention and control of NEC.