The Role of Glycosaminoglycans in Protection from Neonatal Necrotizing Enterocolitis: A Narrative Review

miR-375-3p targets YWHAB to attenuate intestine injury in neonatal necrotizing enterocolitis

PURPOSE

Necrotizing enterocolitis (NEC) is a significant contributor to neonatal mortality. This study aimed to investigate the role of high levels of miR-375-3p in breast milk in the development of NEC and elucidate its mechanism.

METHODS

Differential expression of miR-375-3p in the intestines of breast-fed and formula-fed mice was confirmed using real-time polymerase chain reaction (RT-PCR). NEC mice models were established, and intestinal injury was assessed using HE staining. RT-PCR and Western blot were conducted to examine the expression of miR-375-3p, tyrosine 3-monooxygenase/tryptophan 5-monooxygenase activation protein β (YWHAB), as well as the inflammatory in IEC-6 cells, and intestinal tissues obtained from NEC mice and patients. Flow cytometry and cell counting kit-8 (CCK-8) were employed to elucidate the impact of miR-375-3p and YWHAB on cell apoptosis and proliferation.

RESULTS

Breastfeeding increases miR-375-3p expression in the intestines. The expression of miR-375-3p in NEC intestinal tissues exhibited a significant decrease compared to the healthy group. Additionally, the expression of interleukin-6 (IL-6), interleukin-10 (IL-10), and tumor necrosis factor-α (TNF-α) was higher in the NEC group compared to the control group. Down-regulation of miR-375-3p inhibited IEC-6 cell proliferation, increased apoptosis, and elevated secretion of inflammatory factors. Bioinformatics revealed that YWHAB may be a target of miR-375-3p. RT-PCR and Western blot indicated a down-regulation of YWHAB expression in intestines of NEC patients and mice. Furthermore, YWHAB was found to be positively connected with miR-375-3p. Knockdown miR-375-3p down-regulated YWHAB expression in cells. Inhibition of YWHAB exhibited similar effects to miR-375-3p in IEC-6 cells. YWHAB plasmid partially reverse cellular functional impairment induced by miR-375-3p knockdown.

CONCLUSIONS

Breastfeeding elevated miR-375-3p expression in intestines in neonatal mice. MiR-375-3p leads to a decrease in apoptosis of intestinal epithelial cells, an increase in cell proliferation, and a concomitant reduction in the expression of inflammatory factors partly through targeting YWHAB.

Effect of Oral Chondroitin Sulfate Supplementation on Acute Brain Injury in a Murine Necrotizing Enterocolitis Model

BACKGROUND

Necrotizing enterocolitis (NEC) is a devastating condition where inflammatory changes and necrosis in the gut results in activation of brain microglia and subsequent neurodevelopmental impairment. Chondroitin sulfate (CS) is a glycosaminoglycan in human breast milk that is absent in conventional formulas. We hypothesized that oral formula supplementation with CS during a murine model of experimental NEC would not only attenuate intestinal injury, but also brain injury.

STUDY DESIGN

NEC was induced in mouse pups on postnatal days (PNDs) 5 to 8. Three conditions were studied: (1) breastfed controls, (2) NEC, and (3) NEC+enteral CS (formula+200 mg/kg/d of CS). Pups were euthanized on PND 9 or reunited with dams by the evening of PND 8. Intestinal segments were H&E stained, and immunohistochemistry was performed on brain tissue for Iba-1 to assess for microglial morphology and cortical changes. Neurodevelopmental assays were performed on mice reunited with foster dams on PND 9. Single-cell RNA-sequencing analysis was performed on human intestinal epithelial cells exposed to (1) nothing, (2) hydrogen peroxide (H 2 O 2 ) alone, or (3) H 2 O 2 + CS to look at the differential gene expression between groups. Groups were compared with ANOVA or Kruskal-Wallis tests as appropriate with p < 0.05 considered significant.

RESULTS

Compared with NEC, mice treated with oral CS showed improved clinical outcomes, decreased intestinal injury, and attenuated microglial activation and deleterious cortical change. Mice with CS performed better on early neurodevelopmental assays when compared with NEC alone. Single-cell analysis of HIEC-6 cells demonstrated that CS treatment down regulated several inflammatory pathways including nuclear factor κB-suggesting an explanation for the improved Th17 intestinal cytokine profile.

CONCLUSIONS

Oral CS supplementation improved both physiological, clinical, and developmental outcomes. These data suggest that CS is a safe compound for formula supplementation for the prevention of NEC.

Chondroitin sulfate supplementation improves clinical outcomes in a murine model of necrotizing enterocolitis

Necrotizing enterocolitis (NEC) continues to be a devastating disease in preterm neonates and has a paucity of medical management options. Chondroitin sulfate (CS) is a naturally occurring glycosaminoglycan (GAG) in human breast milk (HM) and has been shown to reduce inflammation. We hypothesized that supplementation with CS in an experimental NEC model would alter microbial diversity, favorably alter the cytokine profile, and (like other sulfur compounds) improve outcomes in experimental NEC via the eNOS pathway. NEC was induced in 5-day-old pups. Six groups were studied (n = 9-15/group): (1) WT breastfed and (2) Formula fed controls, (3) WT NEC, (4) WT NEC + CS, (5) eNOS KO (knockout) NEC, and (6) eNOS KO NEC + CS. Pups were monitored for clinical sickness score and weights. On postnatal day 9, the pups were killed. Stool was collected from rectum and microbiome analysis was done with 16 s rRNA sequencing. Intestinal segments were examined histologically using a well-established injury scoring system and segments were homogenized and analyzed for cytokine profile. Data were analyzed using GraphPad Prism with p < 0.05 considered significant. CS supplementation in formula improved experimental NEC outcomes when compared to NEC alone. CS supplementation resulted in similar improvement in NEC in both the WT and eNOS KO mice. CS supplementation did not result in microbial changes when compared to NEC alone. Our data suggest that although CS supplementation improved outcomes in NEC, this protection is not conferred via the eNOS pathway or alteration of microbial diversity. CS therapy in NEC does improve the intestinal cytokine profile and further experiments will explore the mechanistic role of CS in altering immune pathways in this disease.

Impact of neonatal nutrition on necrotizing enterocolitis

Necrotizing enterocolitis (NEC) is the leading cause of morbidity and mortality in preterm infants. NEC is multifactorial and the result of a complex interaction of feeding, dysbiosis, and exaggerated inflammatory response. Feeding practices in the neonatal intensive care units (NICUs) can vary among institutions and have significant impact on the vulnerable gastointestinal tract of preterm infants. . These practices encompass factors such as the type of feeding and fortification, duration of feeding, and rate of advancement, among others. The purpose of this article is to review the data on some of the most common feeding practices in the NICU and their impact on the development of NEC in preterm infants. Data on the human milk bioactive component glycosaminoglycans, specifically hyaluronan, will also be discussed in the context of postnatal intestinal development and NEC prevention.

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. β-glucan has manifested multiple biological effects including anti-inflammatory, regulation of gut microbiota, and immunomodulatory activities. 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 gavaged with either 1 mg/ml β-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-κB 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

β-glucan administration ameliorated intestinal injury of NEC mice; reduced the intestinal expression of TLR4, NF-κB, IL-1β, IL-6, and TNF-α; 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 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 prevents against NEC in neonatal mice, possibly by suppressing the TLR4-NF-κB signaling pathway, improving intestinal barrier function, and partially regulating intestinal microbiota.

Effect of Hyaluronic Acid 35 kDa on an In Vitro Model of Preterm Small Intestinal Injury and Healing using Enteroid-derived Monolayers

In vitro scratch wound assays are commonly used to investigate the mechanisms and characteristics of epithelial healing in a variety of tissue types. Here, we describe a protocol to generate a two-dimensional (2D) monolayer from three-dimensional (3D) non-human primate enteroids derived from intestinal crypts of the terminal ileum. These enteroid-derived monolayers were then utilized in an in vitro scratch wound assay to test the ability of hyaluronan 35 kDa (HA35), a human milk HA mimic, to promote cell migration and proliferation along the epithelial wound edge. After the monolayers were grown to confluency, they were manually scratched and treated with HA35 (50 µg/mL, 100 µg/mL, 200 µg/mL) or control (PBS). Cell migration and proliferation into the gap were imaged using a transmitted-light microscope equipped for live-cell imaging. Wound closure was quantified as percent wound healing using the Wound Healing Size Plugin in ImageJ. The scratch area and rate of cell migration and the percentage of wound closure were measured over 24 h. HA35 in vitro accelerates wound healing in small intestinal enteroid monolayers, likely through a combination of cell proliferation at the wound edge and migration to the wound area. These methods can potentially be used as a model to explore intestinal regeneration in the preterm human small intestine.

A mini-review of advances in intestinal flora and necrotizing enterocolitis

Necrotizing enterocolitis (NEC) is a digestive disease that frequently occurs in premature infants with low gestational age and low birth weight, and seriously threatens the life of NEC patients. NEC pathogenesis is recognized to be affected by multiple factors, such as preterm birth, formula feeding, and low birth weight. As a popular object for the past decades, intestinal flora is commonly used in NEC-related studies, and intestinal disorder is considered as a critical risk factor for the occurrence and development of NEC. The colonization of abnormal microbiota into gastrointestinal micro-ecosystem can easily lead to the damage of intestinal mucosal barrier, destruction of immune function, inflammatory reaction, and further the occurrence of NEC. Although it is a low-cost and safe way to prevent and treat the NEC by early intervention of oral probiotics to regulate the intestinal homeostasis, more studies in the future are still encouraged to narrow the gap between theoretical guidance and practical application.

Expression and Possible Role of Silent Mating Type Information Regulation 2 Homolog 1 in Post-necrotizing Enterocolitis Stricture in vivo and in vitro

PURPOSE

To investigate the expression and possible role of Sirtuin1 or Silent mating-type information regulation 2 homolog-1 (SIRT1) in post-necrotizing enterocolitis stricture.

MATERIALS AND METHODS

The expression characteristics of SIRT1 and TGF-β1 in post-necrotizing enterocolitis stricture were detected by immunohistochemistry. The siRNA-SIRT1 was used to inhibit the expression of SIRT1 in intestinal epithelial cells-6 (IEC-6), and qRT-PCR, WB, and ELISA were utilized to detect the changes of Transforming growth factor-β1 (TGF-β1), nuclear factor (NF)-κB, tumor necrosis factor-α (TNF-α), tight junction protein-1 (ZO-1), and vascular endothelial growth factor (VEGF) expressions. The IEC-6 cell proliferation and migration ability were tested via CCK8 kit and Transwell test. The expression of E-cadherin and Vimentin in cells was detected by immunofluorescence.

RESULTS

The CRP, IL-6, IL-10, and IFN-γ in the serum of Necrotizing enterocolitis (NEC) intestinal stenosis patients were significantly higher than the reference values. The SIRT1 protein was under-expressed and the TGF-β1 protein was overexpressed in NEC intestinal stenosis tissue. And the expression of SIRT1 was negatively correlated with TGF-β1. At the time of diagnosis of NEC, the expression of SIRT1 decreased in children with respiratory distress syndrome and CRP level increased. After inhibiting the expression of SIRT1 in IEC6 cells, the expression levels of TGF-β1, Smad3, and NF-κB were decreased, and the expression of ZO-1 was also decreased. The proliferation and migration ability of IEC6 cells was decreased significantly, and the expression of E-cadherin and Vimentin proteins in IEC6 cells did not change significantly.

CONCLUSION

Promotion of intestinal fibrosis by inflammation may be the mechanism of post-necrotizing enterocolitis stricture. SIRT1 may be a protective protein of NEC. The probable mechanism is that SIRT1 can regulate intestinal fibrosis and can protect the intestinal mucosal barrier function to participate in the process of post-necrotizing enterocolitis stricture.

Acceleration of Small Intestine Development and Remodeling of the Microbiome Following Hyaluronan 35 kDa Treatment in Neonatal Mice

The beneficial effects of human milk suppressing the development of intestinal pathologies such as necrotizing enterocolitis in preterm infants are widely known. Human milk (HM) is rich in a multitude of bioactive factors that play major roles in promoting postnatal maturation, differentiation, and the development of the microbiome. Previous studies showed that HM is rich in hyaluronan (HA) especially in colostrum and early milk. This study aims to determine the role of HA 35 KDa, a HM HA mimic, on intestinal proliferation, differentiation, and the development of the intestinal microbiome. We show that oral HA 35 KDa supplementation for 7 days in mouse pups leads to increased villus length and crypt depth, and increased goblet and Paneth cells, compared to controls. We also show that HA 35 KDa leads to an increased predominance of Clostridiales Ruminococcaceae, Lactobacillales Lactobacillaceae, and Clostridiales Lachnospiraceae. In seeking the mechanisms involved in the changes, bulk RNA seq was performed on samples from the terminal ileum and identified upregulation in several genes essential for cellular growth, proliferation, and survival. Taken together, this study shows that HA 35 KDa supplemented to mouse pups promotes intestinal epithelial cell proliferation, as well as the development of Paneth cells and goblet cell subsets. HA 35 KDa also impacted the intestinal microbiota; the implications of these responses need to be determined.

It's all in the milk: chondroitin sulfate as potential preventative therapy for necrotizing enterocolitis

Necrotizing enterocolitis (NEC) is a devastating condition affecting up to 5% of neonatal intensive care unit (NICU) admissions. Risk factors include preterm delivery, low birth weight, and antibiotic use. The pathogenesis is characterized by a combination of intestinal ischemia, necrosis of the bowel, reperfusion injury, and sepsis typically resulting in surgical resection of afflicted bowel. Targeted medical therapy remains elusive. Chondroitin sulfate (CS) holds the potential to prevent the onset of NEC through its anti-inflammatory properties and protective effect on the gut microbiome. The purpose of this review is to outline the many properties of CS to highlight its potential use in high-risk infants and attenuate the severity of NEC. The purpose of this review is to (1) discuss the interaction of CS with the infant microbiome, (2) review the anti-inflammatory properties of CS, and (3) postulate on the potential role of CS in preventing NEC. IMPACT: NEC is a costly medical burden in the United States. Breast milk is the best preventative measure for NEC, but not all infants in the NICU have access to breast milk. Novel therapies and diagnostic tools are needed for NEC. CS may be a potential therapy for NEC due to its potent anti-inflammatory properties. CS could be added to the formula in an attempt to mitigate breast milk disparities.