Comparison of preoperative and intraoperative surgeon diagnosis and pathologic findings in spontaneous intestinal perforation vs necrotizing enterocolitis

OBJECTIVE

To investigate the accuracy of preoperative and intraoperative diagnosis via comparison to pathologic diagnosis in spontaneous intestinal perforation (SIP) vs. necrotizing enterocolitis (NEC).

STUDY DESIGN

A retrospective review of neonates <1500 g treated for pneumoperitoneum between 07/2004-09/2022 was conducted. Patients treated for NEC medically prior to diagnosis and those treated with drain only were excluded. Fleiss' Kappa analysis assessed agreement between all three diagnoses: preoperative, intraoperative, and pathologic.

RESULT

Overall, 125 patients were included with mean birthweight 834.2 g (SD:259.2) and mean gestational age 25.8 weeks (SD:2.2). Preoperative and intraoperative diagnoses agreed in 90.3%, intraoperative and pathologic agreed in 71.1%, and preoperative and pathologic agreed in 75.2% of patients. Fleiss' Kappa was 0.55 (95% CI:0.43,0.68), indicating moderate agreement between the three diagnoses.

CONCLUSION

Our study shows moderate agreement between preoperative, intraoperative, and pathologic diagnoses. Further studies investigating the clinical characteristics of SIP and NEC are needed to improve diagnostic accuracy and management.

Evaluation of the protective and therapeutic effects of extra virgin olive oil rich in phenol in experimental model of neonatal necrotizing enterocolitis by clinical disease score, ınflammation, apoptosis, and oxidative stress markers

BACKGROUND AND AIM

Necrotizing Enterocolitis (NEC) is an inflammation-associated ischemic necrosis of the intestine. To investigate the effects of extra virgin olive oil (EVOO) on inflammation, oxidative stress, apoptosis, and histological changes in NEC-induced newborn rats.

MATERIALS AND METHODS

24 rats were randomly divided into three groups: control, NEC and NEC + EVOO. NEC induction was performed using hypoxia-hyperoxia, formula feeding, and cold stress. The NEC + EVOO group received 2 ml/kg EVOO with high phenolic content by gavage twice a day for 3 days. 3 cm of bowel including terminal ileum, cecum, and proximal colon was excised.

RESULTS

Weight gain and clinical disease scores were significantly higher in the NEC + EVOO group than in the NEC group (p < 0.001). EVOO treatment caused significant decreases in IL1β, IL6 levels (p = 0.016, p = 0.029 respectively) and EGF, MDA levels (p = 0.032, p = 0.013 respectively) compared to NEC group. Significant decreases were observed in IL6 gene expression in the NEC + EVOO group compared to the NEC group (p = 0.002). In the group NEC + EVOO, the number of Caspase-3 positive cells was found to be significantly reduced (p < 0.001) and histopathological examination revealed minimal changes and significantly lower histopathological scores (p < 0.001).

CONCLUSION

Phenol-rich EVOO prevents intestinal damage caused by NEC by inhibiting inflammation, oxidative stress, apoptosis.

Potential role of bile acids in the pathogenesis of necrotizing enterocolitis

Necrotizing enterocolitis (NEC) is one of the most common acute gastrointestinal diseases in preterm infants. Recent studies have found that NEC is not only caused by changes in the intestinal environment but also by the failure of multiple systems and organs, including the liver. The accumulation of bile acids (BAs) in the ileum and the disorder of ileal BA transporters are related to the ileum injury of NEC. Inflammatory factors such as tumor necrosis factor (TNF)-α and interleukin (IL)-18 secreted by NEC also play an important role in regulating intrahepatic BA transporters. As an important link connecting the liver and intestinal circulation, the bile acid metabolic pathway plays an important role in the regulation of intestinal microbiota, cell proliferation, and barrier protection. In this review, we focus on how bile acids explore the dynamic changes of bile acid metabolism in necrotizing enterocolitis and the potential therapeutic value of targeting the bile acid signaling pathways.

Active polypeptide MDANP protect against necrotizing enterocolitis (NEC) by regulating the PERK-eIF2ɑ-QRICH1 axis

The effect of MDANP effects on ER stress signalling not well known or elucidated. Endoplasmic reticulum (ER) stress plays a critical role in necrotizing enterocolitis (NEC) pathogenesis through the PERK-eIF2ɑ-QRICH1 axis. The present study aimed to explore the protective effects of MDANP in NEC development. Firstly, a function screening was designed to identify the candidate peptides in human milk, and then the identified peptides were validated in NEC patients. In vivo, NEC was induced in mice pups and divided into four groups: (1) control group, (2) NEC group, (3) MDANP + NEC group, and (4) NS + NEC group. In vitro, lentivirus-mediated QRICH1 silencing, was used to transfect NCM460 cell lines, then stimulated with LPS. After LPS stimulation, cells were treated with chemically synthesized MDANP, and the essential proteins in the QRICH1 signalling pathway in cells were tested and compared. After the small-scale screening, a peptide (SKSKKFRRPDIQYPDATDED) named MDANP was determined as the principal peptide. Its protective effect against NEC through inhibiting the expression of ERS key proteins and impeding the intestinal cells' apoptosis was observed in the animal models. Furthermore, the inhibitive effect of MDANP on apoptosis of intestinal epithelial cells through modulating the PERK-eIF2ɑ-QRICH1 ERS pathway was also confirmed in vitro. Taken together, our data suggest that MDANP effectively ameliorates apoptosis in NEC through attenuating PERK-eIF2ɑ-QRICH1.

Persistent Proclivity to a Proinflammatory State in a Human Enteroid Model of Necrotizing Enterocolitis

Background: Necrotizing enterocolitis (NEC) is a devastating disease of premature neonates with substantial morbidity and mortality. Necrotizing enterocolitis is associated with prematurity, a hyperinflammatory response, and dysregulation of intestinal barrier function. We hypothesize that patients with NEC will have an increased hyperinflammatory intestinal response compared with those without NEC. Patients and Methods: Enteroids were generated from intestinal tissue from neonates undergoing resection. They were treated with 100 mcg/mL lipopolysaccharide (LPS), subjected to 24 hours of hypoxia inducing experimental NEC, then compared with untreated controls. Expression of tumor necrosis factor (TNF-α) and interleukin 8 (IL-8) were evaluated via reverse transcriptase-quantitative polymerase chain reaction (RT-qPCR) and enzyme-linked immunosorbent assay (ELISA) to measure inflammatory response. Analysis of variance (ANOVA) determined statistical significance (p < 0.05). Results: Treated NEC-derived enteroids expressed significantly higher levels of IL-8 (RT-qPCR, p = 0.003; ELISA, p = 0.0002) compared with untreated NEC-derived enteroids with an increase in inflammatory marker concentration in those with a greater degree of prematurity (ELISA, p = 0.0015). A higher level of IL-8 was seen in NEC-derived enteroids compared with control after treatment (RT-qPCR, p = 0.024). Tumor necrosis factor-α levels were elevated in treated NEC-derived enteroids compared with untreated NEC-derived enteroids (RT-qPCR, p = 0.006; ELISA, p = 0.002) and compared with treated non-NEC-derived enteroids (RT-qPCR, p = 0.025; ELISA, p < 0.0001). Conclusions: Enteroids generated from neonates with NEC have an elevated hyperinflammatory response in response to NEC-inducing stimuli compared with controls. Enteroids generated from neonates with NEC with a greater degree of prematurity have a larger increase in inflammatory markers. This tendency toward a hyperinflammatory state may be correlated with an infant's proclivity to develop NEC and further demonstrates the hyperinflammatory state of prematurity.

Association of Placental Pathologic Findings with the Severity of Necrotizing Enterocolitis in Preterm infants - A Matched Case-Control Study

OBJECTIVE

To determine the association of placental pathology with the severity of necrotizing enterocolitis (NEC) in preterm infants.

METHODS

This single-center matched case-control study included infants with NEC (n = 107) and gestational age and birth weight-matched controls (n = 130), born between 2013 and 2020. Placentas were evaluated according to the Amsterdam Placental Workshop Group Consensus Statement.

RESULTS

Acute histologic chorioamnionitis with the fetal response was significantly more common in infants with surgical NEC vs. medical NEC (35.4% vs. 15.3%; p = 0.02). On regression model, infants with multiple placental pathologies (OR 2.16; 95% CI 1.01 - 4.73; p = 0.04) and maternal vascular malperfusion (OR 2.2; 95% CI 1.12 - 4.51; p = 0.02) had higher odds of either medical or surgical NEC than controls.

CONCLUSION

Infants with multiple placental lesions, including placental inflammatory and vascular lesions, were at higher risk of medical or surgical NEC in the postnatal period.

Rhus chinensis Mill. fruits prevent necrotizing enterocolitis in rat pups via regulating the expressions of key proteins involved in multiple signaling pathways

ETHNOPHARMACOLOGICAL RELEVANCE

Based on ancient records and previous studies, many parts of Rhus chinensis Mill., including the fruits, have good preventive and therapeutic effects on inflammation, malaria, diarrhea, and gastrointestinal diseases. Rhus plants and Galla chinensis produced from R. chinensis leaves can also prevent or cure intestinal diseases. However, the preventive effect and molecular mechanisms of R. chinensis fruits on necrotizing enterocolitis (NEC) have not been comprehensively studied.

AIM OF THE STUDY

This article aims to estimate the effect of the 80% ethanol extract of R. chinensis fruits (RM) on alleviating NEC in rat pups and illustrate the potential molecular mechanisms.

MATERIALS AND METHODS

Rat pups were subjected to formula feeding, intermittent hypoxic, and cold stresses to establish the NEC model. The preventive effects of RM on NEC were evaluated through survival rate; clinical sickness index; macroscopic conditions; histopathology; and expression levels of inflammatory markers (i.e., tumor necrosis factor-α [TNF-α], interleukin-6 [IL-6]), oxidative stress indicators (i.e., total antioxidant status [TAS], total oxidant status [TOS], superoxide dismutase [SOD], glutathione peroxidase [GSH-Px], myeloperoxidase [MPO], malondialdehyde [MDA]), and tight junction proteins (i.e., Zonula Occludens 1 [ZO-1], Occludin). Moreover, the expression levels of several key proteins involved in oxidative stress (i.e., nuclear factor erythroid 2-related factor 2 [Nrf2], NAD(P)H-quinone oxidoreductase-1 [NQO1]), inflammation (i.e., Toll-like receptor 4 [TLR4], phosphorylated-nuclear factor kappa-B [p-NF-κB], inducible nitric oxide synthase [iNOS]), and apoptosis (i.e., cleaved cysteinyl aspartate specific proteinase-3 [cleaved Caspase-3], Bcl-2-associated X [Bax], B-cell lymphoma-2 [Bcl-2]) in intestinal tissues were analyzed to clarify the molecular mechanisms.

RESULTS

The extract particularly high doses (400 mg RM/kg body weight) could remarkably reduce the mortality and clinical sickness score and improve the macroscopic condition and histopathological injury of the intestine in NEC pups. After RM administration, the levels of TOS, TNF-α, IL-6, MPO, and MDA in the bowel tissue decreased, whereas the levels of TAS, SOD, and GSH-Px were significantly enhanced. The expression levels of ZO-1 and Occludin proteins were dramatically augmented in RM-treated groups to maintain intestinal barrier integrity. Further analyses revealed that RM might prevent NEC pups by improving some pivotal proteins involved in oxidative stress, inflammation, and apoptosis of enterocytes, namely, by down-regulating the levels of TLR4, p-NF-κB, iNOS, cleaved Caspase-3, and Bax and up-regulating the levels of Bcl-2, NQO1, and Nrf2.

CONCLUSIONS

The RM prevented the intestinal inflammation and damage caused by NEC by regulating the expression of several pivotal proteins involved in oxidative stress, inflammation, and apoptosis. This study might provide a scientific basis for R. chinensis fruits as a traditional herbal medicine to prevent and/or alleviate NEC.

Sulforaphane Ameliorates the Intestinal Injury in Necrotizing Enterocolitis by Regulating the PI3K/Akt/GSK-3β Signaling Pathway

Objective

Necrotizing enterocolitis (NEC) is a serious neonatal disease; this study aims to investigate the role of sulforaphane (SFN) in NEC-induced intestinal injury.

Methods

An animal model of NEC was established in newborn mice and intragastrically administrated with SFN; then, the general status and survival of the mice were observed. H&E staining was used to observe the pathological changes of intestinal tissues. ELISA, immunohistochemical staining, and flow cytometry assays were used to detect the levels of inflammatory factors, including TNF-α, IL-6, and IL-17, the expression of Bax, Bcl-2, TLR4, and NF-κB, and the percentages of the Th17 and Treg cells, respectively. GSK-3β expression levels were measured by immunofluorescence. IEC-6 and FHC cells were induced with LPS to mimic NEC in vitro and coincubated with SFN; then, the inflammatory factor levels and cell apoptosis rate were detected. Finally, Western blot was used to assess the expression of PI3K/Akt/GSK-3β pathway-related proteins in vitro and in vivo.

Results

SFN improved the survival rate of NEC mice during modeling, alleviated the severity of the intestinal injury, and reduced the proportion of Th17/Treg cells. SFN could inhibit TLR4 and NF-κB levels, decrease the release of inflammatory factors TNF-α and IL-6, suppress Bax expression, increase Bcl-2 expression, and inhibit apoptosis both in in vitro and in vivo models of NEC. Meanwhile, SFN regulated the expression of PI3K/Akt/GSK-3β pathway-related proteins in vitro and in vivo.

Conclusion

SFN relieved the inflammatory response and apoptosis by regulating the PI3K/Akt/GSK-3β signaling pathway, thereby alleviating NEC in model mice and cells.

[Expression and Role of PD-L1 in a Mouse Model of Necrotizing Enterocolitis]

Objective

To investigate the expression and role of programmed death ligand-1 (PD-L1) in a mouse model of necrotizing enterocolitis (NEC).

Methods

A total of 20 wild-type C57 BL/6 J mice were randomly assigned to the control and the model groups. Mice in the control group were breastfed, while mice in the model group were given lipopolysaccharide, formula feeding, hypoxia, and cold stimulation for NEC induction. Then, the intestines of the mice were collected in order to assess the pathological changes through HE staining, to examine PD-L1 expression and localization with immunofluorescence co-localization, and to evaluate intestinal PD-L1 expression with Western blot. Peripheral blood was collected for flow cytometry to examine leukocyte subpopulations and their PD-L1 expression. On the other hand, 14 PD-L1 (+/+) mice and 14 PD-L1 (-/-) mice were randomly divided into their respective genotype control groups and model groups. The same induction method as was already mentioned was adopted for the model groups. The intestines of the mice were collected for HE staining to evaluate the pathological change and peripheral blood was collected to examine the expression of inflammatory factors.

Results

The NEC mouse model was successfully constructed. PD-L1 was widely expressed in enterocytes and inflammatory cells in the mouse intestines and in T cells, monocytes, and neutrophils in peripheral blood. The expression of PD-L1 in NEC mouse intestines increased in comparison with that of the control group. In the peripheral blood of NEC mice, the proportion of T cells and monocytes and their PD-L1 expression showed no significant changes compared with those of the control group, while the proportion of neutrophils and their PD-L1 expression increased by about 140% and 150%, respectively, in comparison with those of the control group ( P<0.05). According to the results of the PD-L1 gene mouse experiment, the control groups of PD-L1 (+/+) mice and PD-L1 (-/-) mice showed no significant difference in their intestinal conditions and serum inflammatory factor levels, while the PD-L1 (-/-) NEC mouse had worse intestinal pathological changes and increased mean pathological scores compared with those of PD-L1 (+/+) NEC mouse ( P<0.05). In addition, serum interleukin (IL)-10 in PD-L1 (-/-) NEC mouse decreased by about 44% compared with that of PD-L1 (+/+) NEC mice, and chemokine (C-X-C motif) ligand 1/IL-6/IL-1β all increased by more than 25% (all P<0.05).

Conclusion

PD-L1 is widely expressed in inflammatory cells and enterocytes in mice. Knocking out PD-L1 aggravates the degree of NEC inflammation and intestinal pathological changes. PD-L1 plays a protective role by reducing inflammation in the pathogenesis of NEC, the mechanism of which may be related to the regulation of neutrophils/enterocytes.

Reduced Incidence of Necrotizing Enterocolitis due to the Anti-Inflammatory Effects of CXCL14 in Intestinal Tissue

Bioinformatic analysis indicated that downregulated CXCL14 will occur in the intestinal tissue of patients with necrotizing enterocolitis (NEC). To reveal the relationship between CXCL14 and mucosal immune regulation, we designed and implemented the experiments to explore the potential function of CXCL14 in the pathogenesis of NEC. Firstly, this study confirmed that the expression of CXCL14 decreased in the intestinal tract of NEC children. Secondly, the experiments results showed that CXCL14 could ameliorate the inflammatory injury of intestinal tissue through the suppressive effect on the expression of TNF-α and INF-γ in vivo. Finally, we explained that activation of the TLR4 can reduce the expression level of CXCL14 in the intestinal tissue of mouse pups. Collectively, our study suggested that CXCL14 may negatively regulate the inflammatory response in intestinal tissue and play an essential role in NEC development and progression.

DRG1 Maintains Intestinal Epithelial Cell Junctions and Barrier Function by Regulating RAC1 Activity in Necrotizing Enterocolitis

BACKGROUND

An immature intestine is a high-risk factor for necrotizing enterocolitis (NEC), which is a serious intestinal disease in newborns. The regulation of developmentally regulated GTP-binding protein 1 (DRG1) during organ development suggests a potential role of DRG1 in the maturation process of the intestine.

AIM

To illustrate the function of DRG1 during the pathogenesis of NEC.

METHODS

DRG1 expression in the intestine was measured using immunohistochemistry and q-PCR. Immunoprecipitation coupled with mass spectrometry was used to identify the interacting proteins of DRG1. The biological functions of the potential interactors were annotated with the Database for Annotation, Visualization and Integrated Discovery. Caco2 and FHs74Int cells with stable DRG1 silencing or overexpression were used to investigate the influence of DRG1 on cell junctions and intestinal barrier permeability and to elucidate the downstream mechanism.

RESULTS

DRG1 was constitutively expressed during the intestinal maturation process but significantly decreased in the ileum in the context of NEC. Protein interaction analysis revealed that DRG1 was closely correlated with cell junctions. DRG1 deficiency destabilized the E-cadherin and occludin proteins near the cell membrane and increased the permeability of the epithelial cell monolayer, while DRG1 overexpression prevented lipopolysaccharide-induced disruption of E-cadherin and occludin expression and cell monolayer integrity. Further investigation suggested that DRG1 maintained cell junctions, especially adherens junctions, by regulating RAC1 activity, and RAC1 inhibition with NSC23766 attenuated intestinal injury and led to improved barrier integrity in experimental NEC.

CONCLUSIONS

Our findings illustrate the mechanism underlying the effect of DRG1 deficiency on epithelial cell permeability regulation and provide evidence supporting the application of RAC1 inhibitors for protection against NEC.

Neutrophil extracellular trap inhibition increases inflammation, bacteraemia and mortality in murine necrotizing enterocolitis

Necrotizing enterocolitis (NEC) is a devastating gastrointestinal disease affecting primarily premature infants. The disease is characterized by intestinal inflammation and leucocyte infiltration, often progressing to necrosis, perforation, systemic inflammatory response and death. Neutrophil extracellular traps (NETs), denoting nuclear DNA, histone and antimicrobial protein release, have been suggested to play a role in NEC. This study aimed to determine the role of NETs in NEC and explore the effect of chloramidine, a NET inhibitor, on a murine NEC-like intestinal injury model. Blood and intestinal tissues were collected from infants diagnosed with ≥ Stage II NEC, and levels of nucleosomes and NETs, respectively, were compared with those of case-matched controls. In mice, NEC was induced with dithizone/Klebsiella, and mice in the treatment group received 40 mg/kg chloramidine. Bacterial load, intestinal histology, plasma myeloperoxidase and cytokine levels, and immunofluorescent staining were compared with controls. Nucleosomes were significantly elevated in both human and mouse NEC plasma, whereas NET staining was only present in NEC tissue in both species. Chloramidine treatment increased systemic inflammation, bacterial load, organ injury and mortality in murine NEC. Taken together, our findings suggest that NETs are critical in the innate immune defence during NEC in preventing systemic bacteraemia.

An Update on the Role of Extracellular Vesicles in the Pathogenesis of Necrotizing Enterocolitis and Inflammatory Bowel Diseases

Some of the most fundamental influences of microorganisms inhabiting the human intestinal tract are exerted during infant development and impact the maturation of intestinal mucosa and gut immune system. The impact of bacteria on the host gut immune system is partially mediated via released extracellular vesicles (EVs). The heterogeneity in EV content, size, and bacterial species origin can have an impact on intestinal cells, resulting in inflammation and an immune response, or facilitate pathogen entry into the gut wall. In mammals, maintaining the integrity of the gut barrier might also be an evolutionary function of maternal milk EVs. Recently, the usage of EVs has been explored as a novel therapeutic approach in several pathological conditions, including necrotizing enterocolitis (NEC) and inflammatory bowel disease (IBD). In this review, we attempt to summarize the current knowledge of EV biology, followed by a discussion of the role that EVs play in gut maturation and the pathogenesis of NEC and IBD.

Neurodevelopmental Outcomes at 18-24 Months of Corrected Age in Very Low Birth Weight Infants with Late-onset Sepsis

BACKGROUND

Preterm infants are prone to sepsis owing to their immature innate immunity and prolonged hospitalization. We aimed to evaluate the association between late-onset sepsis (LOS) during hospitalization and neurodevelopmental delay at 18-24 months of corrected age in very low birth weight infants (VLBWIs), and to ascertain this association when adjusted for perinatal risk factors.

METHODS

This is a population-based study of VLBWIs born at 23-32 weeks of gestation between January 2014 and December 2017 who were enrolled in the Korean Neonatal Network. Bayley scales of infant development were evaluated at 18-24 months of corrected age in 2,098 infants. To test for LOS as a risk factor for neurodevelopmental delay, multiple logistic regression was used and adjusted for parental education status and clinical variables.

RESULTS

Blood culture positive LOS was identified in 419 (20.0%) infants. Cognitive and motor delays were found in 392 (18.7%) and 347 (16.5%) infants, respectively. When multivariate analysis was performed, LOS had a significant association with cognitive delay (odds ratio, 1.48; 95% confidence interval, 1.02-2.16), but no association with motor delay in VLBWIs. Both delays were significantly more frequent in cases of intraventricular hemorrhage (IVH) ≥ grade 3, periventricular leukomalacia (PVL), and intrauterine growth restriction (IUGR) and duration of mechanical ventilation. Male sex and necrotizing enterocolitis ≥ grade 2 had an effect on motor delay, whereas paternal college graduation affected cognitive delay.

CONCLUSION

In VLBWIs with LOS, there is a heightened risk of cognitive delays at 18-24 months of corrected age. Brain injury, such as severe IVH and PVL, duration of mechanical ventilation, and IUGR, were also associated with cognitive and motor delays.

miR‑34a increases inflammation and oxidative stress levels in patients with necrotizing enterocolitis by downregulating SIRT1 expression

The miR‑34a/SIRT1 signaling axis is an important signaling axis in tumors and diseases. Notably, low SIRT1 expression in the intestinal tissues of patients with necrotizing enterocolitis (NEC) has been reported. However, whether miR‑34a/SIRT1 signaling as a target to protect the intestines during the NEC process is unclear and remains to be elucidated. Blood samples were collected from 30 patients with NEC, and an NEC rat model was used. The miR‑34a and SIRT1 gene and protein expression levels were assayed by qPCR and Western blotting method. The inflammatory cytokine levels and oxidative stress levels were detected using the ELISA method. The results demonstrated that birth weight, albumin and glucose concentrations were significantly decreased in the NEC patient group compared with the control group, but the C‑reactive protein (CRP) and procalcitonin (PCT) concentrations were significantly increased. The miR‑34a expression level was notably increased in the NEC group, but the SIRT1 expression level was markedly decreased. Notably, the miR‑34a was significantly correlated with NEC severity and the concentrations of CRP, PCT, IL‑6, TNF‑α, IL‑1β, IL‑8, MCP‑1, VCAM1 and malondialdehyde (MDA), but was significantly negatively correlated with SIRT1 gene expression and the concentration of IL‑10. Intestinal villi damage in NEC rats was decreased with miR‑34a inhibition and SIRT1 activation treatment by decreasing the levels of inflammatory cytokines, including IL‑6, TNF‑α, IL‑1β and IL‑8, and oxidative stress proteins, including MCP‑1, VCAM1, and MDA, as well as increasing the level of the anti‑inflammatory cytokine IL‑10. In addition, the results indicated that miR‑34a inhibition and SIRT1 activation strongly protected the intestine and decreased the damage caused by NEC, not only by decreasing the protein levels of SIRT1, TNF‑α, IL‑1β, IL‑6 and IL‑8, but also by increasing the IL‑10 protein levels. The miR‑34a inhibition and SIRT1 activation may decrease the damage caused by NEC by decreasing proinflammatory cytokines and oxidative stress proteins and by increasing the anti‑inflammatory cytokine pathway. Based on the aforementioned analysis, the miR‑34a and SIRT1 proteins may be potential novel therapeutic targets in NEC.

Human breast milk-derived exosomes may help maintain intestinal epithelial barrier integrity

BACKGROUND

This study explores the functions of exosomes derived from human breast milk (HBM) in vivo and in vitro.

METHODS

HBM-derived exosomes were collected from healthy lactating mothers. In vitro analysis were divided into five groups: (1) a control with no added agents, (2) exosomes added, (3) stimulated with lipopolysaccharide (LPS), (4) pretreated with exosomes and stimulated with LPS, and (5) pretreated with exosome-free HBM and stimulated with LPS. For in vivo analysis, mouse pups were randomly assigned to four groups: (1) a control group of breastfed pups, (2) necrotizing enterocolitis-induced (NEC) pups, (3) pups pretreated with HBM-derived exosomes 6 h before being induced by NEC, and (4) pups pretreated with exosome-free HBM 6 h before NEC induction.

RESULTS

Expression of zonula occludens-1 (ZO-1), claudin-1, and occludin were decreased in groups 3 and 5. In the animal model, mice pups in group 3 showed milder intestinal tissue injury than those in group 2 or 4 and had lower levels of the proinflammatory cytokines and higher levels of epithelial tight-junction proteins than groups 2 and 4.

CONCLUSIONS

HBM-derived exosomes exert beneficial effects in preventing NEC by reducing inflammation and injury to the intestinal epithelium as well as by restoring intestinal tight-junction proteins.

IMPACT

HBM-derived exosomes can help protect the epithelial tight-junction proteins ZO-1, claudin, and occludin from inflammatory attack. This study sought (1) to analyze whether there were differences in exosome levels between the human breast milk (HBM) of mothers who had delivered preterm or at term and (2) to investigate whether these exosomes could help sustain the intestinal epithelial tight-junction proteins ZO-1, claudin-1, and occludin in the presence of NEC in vitro and in vivo.

Breast milk nutrients driving intestinal epithelial layer maturation via Wnt and Notch signaling: Implications for necrotizing enterocolitis

Necrotizing enterocolitis (NEC) is an often lethal, inflammatory disease of the preterm intestine. The underdeveloped immune system plays an important role; however, the initial trigger for NEC development is likely a damaged intestinal epithelial layer. We hypothesize that due to incomplete maturation of different epithelial cell lineages, nutrients and bacteria are able to damage the epithelial cells and cause the (immature) inflammatory response, food intolerance and malabsorption seen in NEC. Intestinal organoid research has shown that maturation of intestinal epithelial cell lineages is orchestrated by two key signaling pathways: Wnt and Notch. In NEC, these pathways are dysregulated by hyperactivation of Toll-like-receptor-4. Breastfeeding decreases the risk of developing NEC compared to formula milk. Here, we review the intricate link between breast milk components, Wnt and Notch signaling and intestinal epithelial maturation. We argue that (nutritional) interventions regulating these pathways may decrease the risk of NEC development in preterm infants.

Causative role of mast cell and mast cell-regulatory function of disialyllacto-N-tetraose in necrotizing enterocolitis

Necrotizing enterocolitis (NEC) remains a fatal gastrointestinal disorder in neonates. Disialyllacto-N-tetraose (DSLNT), a function-unclear human milk-derived hexasaccharide, shows anti-NEC potential in previous animal studies. This study is aimed to explore the role of mast cell (MC), a fundamental cell type of mucosal immune system and protective DSLNT in regulating pathological process of NEC. For this purpose, infantile intestinal-tissues were collected from NEC neonates for examination of MCs and its proteases-positive cells. MC accumulation and MC-specific proteases (chymase, tryptase and dipeptidyl peptidase I) were firstly found in lesioned area of NEC infants in-vivo. Subsequent in-situ experiments on neonatal ileum segments showed that purified MC-chymase induced a destructive epithelial layer shedding from basement and microvascular endothelium damage in infantile intestinal segments. Human foreskin MC-activation model was established and DSLNT were applied; MC products (histamine and MC-proteases) were used as MC activation/degranulation indicators. In this in-vitro model, DSLNT pretreatment suppressed release of histamine, chymase and tryptase by MC to the tissue supernatants during lipopolysaccharide or complement C5a stimulation. Newborn rats were formula-hand-fed with or without DSLNT supplement and exposed to hypoxia/cold-stress to induce experimental-NEC-model. In NEC rats, DSLNT supplementation reduced the incidence and pathological scores of NEC, inhibited local accumulation of MC and reduced cytokines (IL-1β, IL-6 and TNF-α) levels in the ileum of rats. In conclusion, MC was causally implicated in epithelium barrier failure in pathogenesis of NEC. DSLNT favorably modulated MC homeostasis by regulating MC degranulation/accumulation, contributing to attenuated NEC. This indicated novel pathomechanisms and potential targets of NEC.

Interleukin-22 signaling attenuates necrotizing enterocolitis by promoting epithelial cell regeneration

Necrotizing enterocolitis (NEC) is a deadly intestinal inflammatory disorder that primarily affects premature infants and lacks adequate therapeutics. Interleukin (IL)-22 plays a critical role in gut barrier maintenance, promoting epithelial regeneration, and controlling intestinal inflammation in adult animal models. However, the importance of IL-22 signaling in neonates during NEC remains unknown. We investigated the role of IL-22 in the neonatal intestine under homeostatic and inflammatory conditions by using a mouse model of NEC. Our data reveal that Il22 expression in neonatal murine intestine is negligible until weaning, and both human and murine neonates lack IL-22 production during NEC. Mice deficient in IL-22 or lacking the IL-22 receptor in the intestine display a similar susceptibility to NEC, consistent with the lack of endogenous IL-22 during development. Strikingly, treatment with recombinant IL-22 during NEC substantially reduces inflammation and enhances epithelial regeneration. These findings may provide a new therapeutic strategy to attenuate NEC.

Stress and corticotropin releasing factor (CRF) promote necrotizing enterocolitis in a formula-fed neonatal rat model

The etiology of necrotizing enterocolitis (NEC) is not known. Alterations in gut microbiome, mucosal barrier function, immune cell activation, and blood flow are characterized events in its development, with stress as a contributing factor. The hormone corticotropin-releasing factor (CRF) is a key mediator of stress responses and influences these aforementioned processes. CRF signaling is modulated by NEC's main risk factors of prematurity and formula feeding. Using an established neonatal rat model of NEC, we tested hypotheses that: (i) increased CRF levels-as seen during stress-promote NEC in formula-fed (FF) newborn rats, and (ii) antagonism of CRF action ameliorates NEC. Newborn pups were formula-fed to initiate gut inflammation and randomized to: no stress, no stress with subcutaneous CRF administration, stress (acute hypoxia followed by cold exposure-NEC model), or stress after pretreatment with the CRF peptide antagonist Astressin. Dam-fed unstressed and stressed littermates served as controls. NEC incidence and severity in the terminal ileum were determined using a histologic scoring system. Changes in CRF, CRF receptor (CRFRs), and toll-like receptor 4 (TLR4) expression levels were determined by immunofluorescence and immunoblotting, respectively. Stress exposure in FF neonates resulted in 40.0% NEC incidence, whereas exogenous CRF administration resulted in 51.7% NEC incidence compared to 8.7% in FF non-stressed neonates (p<0.001). Astressin prevented development of NEC in FF-stressed neonates (7.7% vs. 40.0%; p = 0.003). CRF and CRFR immunoreactivity increased in the ileum of neonates with NEC compared to dam-fed controls or FF unstressed pups. Immunoblotting confirmed increased TLR4 protein levels in FF stressed (NEC model) animals vs. controls, and Astressin treatment restored TLR4 to control levels. Peripheral CRF may serve as specific pharmacologic target for the prevention and treatment of NEC.

The protective effects of Anakinra in a neonatal rat model of necrotizing enterocolitis

BACKGROUND

Necrotizing enterocolitis (NEC) is a commonly seen life-threatening condition in newborns characterized by ischemic necrosis. This study aimed to investigate anakinra's effects, an interleukin-1 receptor antagonist, on oxidative stress, inflammation, and tissue necrosis in an NEC rat model.

MATERIALS AND METHODS

Forty Wistar albino pups were divided into four groups randomly as follows; group 1, control group; group 2, anakinra-treated control group; group 3, NEC group, group 4, NEC, and anakinra treatment group. The rats were given hyperosmolar formula feeding, and they were exposed to hypoxia after cold stress at +4° C and oxygen in order to create the NEC model. On the fourth day of the experiment, the pups were decapitated, and the intestinal tissues were resected for biochemical and histopathologic examination.

RESULTS

Microscopic injury scores and apoptotic indexes were higher in group 3 than the control group (p<0.001, p=0.002, respectively), and there was a significant decrease after anakinra. Interleukin 1ß and caspase-3 levels increased with NEC and decreased significantly after administration of anakinra (p=0.006, p=0.004, respectively). Malondialdehyde and glutathione peroxidase levels also increased compared with the control group (p=0.019, p=0.002, respectively).

CONCLUSION

In this experimental study, we found that anakinra had anti-inflammatory and antioxidant effects and was protective against intestinal injury and apoptosis.

Human placental-derived stem cell therapy ameliorates experimental necrotizing enterocolitis

Necrotizing enterocolitis (NEC), a life-threatening intestinal disease, is becoming a larger proportionate cause of morbidity and mortality in premature infants. To date, therapeutic options remain elusive. Based on recent cell therapy studies, we investigated the effect of a human placental-derived stem cell (hPSC) therapy on intestinal damage in an experimental NEC rat pup model. NEC was induced in newborn Sprague-Dawley rat pups for 4 days via formula feeding, hypoxia, and LPS. NEC pups received intraperitoneal (ip) injections of either saline or hPSC (NEC-hPSC) at 32 and 56 h into NEC induction. At 4 days, intestinal macroscopic and histological damage, epithelial cell composition, and inflammatory marker expression of the ileum were assessed. Breastfed (BF) littermates were used as controls. NEC pups developed significant bowel dilation and fragility in the ileum. Further, NEC induced loss of normal villi-crypt morphology, disruption of epithelial proliferation and apoptosis, and loss of critical progenitor/stem cell and Paneth cell populations in the crypt. hPSC treatment improved macroscopic intestinal health with reduced ileal dilation and fragility. Histologically, hPSC administration had a significant reparative effect on the villi-crypt morphology and epithelium. In addition to a trend of decreased inflammatory marker expression, hPSC-NEC pups had increased epithelial proliferation and decreased apoptosis when compared with NEC littermates. Further, the intestinal stem cell and crypt niche that include Paneth cells, SOX9+ cells, and LGR5+ stem cells were restored with hPSC therapy. Together, these data demonstrate hPSC can promote epithelial healing of NEC intestinal damage.NEW & NOTEWORTHY These studies demonstrate a human placental-derived stem cell (hPSC) therapeutic strategy for necrotizing enterocolitis (NEC). In an experimental model of NEC, hPSC administration improved macroscopic intestinal health, ameliorated epithelial morphology, and supported the intestinal stem cell niche. Our data suggest that hPSC are a potential therapeutic approach to attenuate established intestinal NEC damage. Further, we show hPSC are a novel research tool that can be utilized to elucidate critical neonatal repair mechanisms to overcome NEC.

Delineating proinflammatory microenvironmental signals by ex vivo modeling of the immature intestinal stroma

The intestinal stroma provides an important microenvironment for immune cell activation. The perturbation of this tightly regulated process can lead to excessive inflammation. We know that upregulated Toll-like receptor 4 (TLR4) in the intestinal epithelium plays a key role in the inflammatory condition of preterm infants, such as necrotizing enterocolitis (NEC). However, the surrounding stromal contribution to excessive inflammation in the pre-term setting awaits careful dissection. Ex vivo co-culture of embryonic day 14.5 (E14.5) or adult murine intestinal stromal cells with exogenous monocytes was undertaken. We also performed mRNAseq analysis of embryonic and adult stromal cells treated with vehicle control or lipopolysaccharide (LPS), followed by pathway and network analyses of differentially regulated transcripts. Cell characteristics were compared using flow cytometry and pHrodo red phagocytic stain, candidate gene analysis was performed via siRNA knockdown and gene expression measured by qPCR and ELISA. Embryonic stromal cells promote the differentiation of co-cultured monocytes to CD11bhighCD11chigh mononuclear phagocytes, that in turn express decreased levels of CD103. Global mRNAseq analysis of stromal cells following LPS stimulation identified TLR signaling components as the most differentially expressed transcripts in the immature compared to adult setting. We show that CD14 expressed by CD11b+CD45+ embryonic stromal cells is a key inducer of TLR mediated inflammatory cytokine production and phagocytic activity of monocyte derived cells. We utilise transcriptomic analyses and functional ex vivo modelling to improve our understanding of unique molecular cues provided by the immature intestinal stroma.

Activated M1 macrophages suppress c-kit expression via TNF-α-mediated upregulation of miR-222 in Neonatal Necrotizing Enterocolitis

BACKGROUND

Activation of intestinal macrophages is implicated in the pathogenesis of neonatal necrotizing enterocolitis (NEC), yet its precise mechanisms remain unclear.

OBJECTIVE

The purpose of this study is to investigate the role of macrophages and TNF-α via an inflammatory MicroRNA in NEC.

MATERIALS AND METHODS

Immunofluorescence (IF) staining of CD68, iNOS, and Arg-1 was employed to identify phenotypes of macrophage in the intestines of NEC infants and NEC mice. Expression of TNF-α, c-kit, and miR-222 was evaluated by qRT-PCR, Western blot, and immunochemical staining from the tissue samples.

RESULTS

Large number of M1 macrophage infiltration was found in the NEC intestines. Expression of CD68, iNOS, and TNF-α were significantly increased, while c-kit was decreased distinctly in the NEC group. In the early phase of NEC mouse model, inhibition of M1 macrophages reduced the incidence of NEC and intestinal inflammation. We found that TNF-α upregulated the expression of miRNA-222 and inhibited the expression of c-kit. Conversely, such decrease of c-kit expression could be reversed by miR-222 antagonists. Furtherly, dual-luciferase assay confirmed that c-kit can be inhibited by miR-222 directly.

CONCLUSION

Macrophages activation in NEC intestine results in an increased inflammatory response and TNF-α production, accompanied with miR-222 upregulation and c-kit suppression. Modulations of M1 macrophages, TNF-α or miR-222 may be potential therapeutic targets for NEC treatment.

The decrease of fucosylation in intestinal epithelium is related to the development of necrotizing enterocolitis

Necrotizing enterocolitis (NEC) is a devastating neonatal gastrointestinal emergency. Fucosylated glycans on intestinal epithelial cells (IECs) play a central role in the maintenance of intestinal homeostasis. Nevertheless, its association with necrotizing enterocolitis is not clear. We examined paraffin-embedded intestinal specimens from participants and found that the NEC patients showed lower intestinal epithelial fucosylation levels than the control patients. In the mouse model of NEC, the percentage of fucosylated epithelial cells (F-ECs) and ILC3s was decreased. Also, the expression levels of IL-22 and Fut2 were reduced. Moreover, the critical role of epithelial fucosylation in NEC was further confirmed by administering the anti-IL-22 antibody, which caused an increase in histological damage, body weight loss, intestinal permeability and proinflammatory cytokine release correlated with a reduction of F-ECs. Overall, intestinal fucosylation deficiency led to increased susceptibility and severity of NEC. Further studies are needed to determine whether modification of intestinal fucosylation affects the development of NEC.

Intestinal Goblet Cell Loss during Chorioamnionitis in Fetal Lambs: Mechanistic Insights and Postnatal Implications

Chorioamnionitis, an important cause of preterm birth, is linked to necrotizing enterocolitis (NEC). NEC is characterized by a disrupted mucus barrier, goblet cell loss, and endoplasmic reticulum (ER) stress of the intestinal epithelium. These findings prompted us to investigate the mechanisms underlying goblet cell alterations over time in an ovine chorioamnionitis model. Fetal lambs were intra-amniotically (IA) exposed to lipopolysaccharides (LPS) for 5, 12, or 24 h, or 2, 4, 8, or 15 d before premature delivery at 125 d gestational age (GA). Gut inflammation, the number, distribution, and differentiation of goblet cells, ER stress, and apoptosis were measured. We found a biphasic reduction in goblet cell numbers 24 h–2 d after, and 15 d after IA LPS exposure. The second decrease of goblet cell numbers was preceded by intestinal inflammation, apoptosis, and crypt ER stress, and increased SAM-pointed domain-containing ETS transcription factor (SPDEF)-positive cell counts. Our combined findings indicated that ER stress drives apoptosis of maturating goblet cells during chorioamnionitis, ultimately reducing goblet cell numbers. As similar changes have been described in patients suffering from NEC, these findings are considered to be clinically important for understanding the predecessors of NEC, and targeting ER stress in this context is interesting for future therapeutics.

Maternal aryl hydrocarbon receptor activation protects newborns against necrotizing enterocolitis

Necrotizing enterocolitis (NEC) is a disease of premature infants characterized by acute intestinal necrosis. Current dogma suggests that NEC develops in response to post-natal dietary and bacterial factors, and so a potential role for in utero factors in NEC remains unexplored. We now show that during pregnancy, administration of a diet rich in the aryl hydrocarbon receptor (AHR) ligand indole-3-carbinole (I3C), or of breast milk, activates AHR and prevents NEC in newborn mice by reducing Toll-like receptor 4 (TLR4) signaling in the newborn gut. Protection from NEC requires activation of AHR in the intestinal epithelium which is reduced in mouse and human NEC, and is independent of leukocyte activation. Finally, we identify an AHR ligand ("A18") that limits TLR4 signaling in mouse and human intestine, and prevents NEC in mice when administered during pregnancy. In summary, AHR signaling is critical in NEC development, and maternally-delivered, AHR-based therapies may alleviate NEC.

Incomplete resection of necrotic bowel may increase mortality in infants with necrotizing enterocolitis

BACKGROUND

Infants with advanced necrotizing enterocolitis (NEC) often need surgical resection of necrotic bowel. We hypothesized that incomplete resection of NEC lesions, signified by the detection of necrotic patches in margins of resected bowel loops, results in inferior clinical outcomes.

METHODS

We reviewed the medical records of infants with surgical NEC in the past 15 years for demographic, clinical, and histopathological data. We also developed statistical models to predict mortality and hospital stay.

RESULTS

Ninety infants with surgical NEC had a mean (±standard error) gestational age of 27.3 ± 0.4 weeks, birth weight 1008 ± 48 g, NEC onset at 25.2 ± 2.4 days, and resected bowel length of 29.2 ± 3.2 cm. Seventeen (18.9%) infants who had complete resection of the necrosed bowel had fewer (4; 23.5%) deaths and shorter lengths of hospital stay. In contrast, a group of 73 infants with some necrosis within the margins of resected bowel had significantly more (34; 46.6%) deaths and longer hospital stay. The combination of clinical and histopathological data gave better regression models for mortality and hospital stay.

CONCLUSION

In surgical NEC, incomplete resection of necrotic bowel increased mortality and the duration of hospitalization. Regression models combining clinical and histopathological data were more accurate for mortality and the length of hospital stay.

IMPACT

In infants with surgical NEC, complete resection of necrotic bowel reduced mortality and hospital stay. Regression models combining clinical and histopathological information were superior at predicting mortality and hospital stay than simpler models focusing on either of these two sets of data alone. Prediction of mortality improved with the combination of antenatal steroids, chorioamnionitis, and duration of post-operative ileus, with severity of inflammation and hemorrhages in resected intestine. Length of hospital stay was shorter in infants with higher gestational ages, but longer in those with greater depth of necrosis or needing prolonged parenteral nutrition or supervised feedings.

Let-7d-5p suppresses inflammatory response in neonatal rats with necrotizing enterocolitis via LGALS3-mediated TLR4/NF-κB signaling pathway

Necrotizing enterocolitis (NEC) is an acute intestinal condition accounting for severe mortality and morbidity in preterm infants. This study aimed to identify the possible roles of let-7d-5p in neonatal rats with NEC. The differentially expressed genes (DEGs) related to NEC were initially screened in silico. After establishment of NEC rat models, measurement of the expression of let-7d-5p, galectin-3 (LGALS3), Toll-like receptor 4 (TLR4), and nuclear factor-κB (NF-κB) as well as proinflammatory cytokines (TNF-α, IL-1β, and IL-6) was conducted. The interaction between let-7d-5p and LGALS3 or argonaute-2 (AGO2) was identified. Gain- and loss-of-function approaches were then performed in an attempt to investigate the regulatory roles of let-7d-5p and LGALS3 in inflammation and cell apoptosis in NEC neonatal rats. Let-7d-5p was poorly expressed, whereas LGALS3, TLR4, and NF-κB were highly expressed, in the intestinal tissues of NEC rats. Overexpression of let-7d-5p resulted in decreased levels of proinflammatory factors in the intestinal tissues of NEC rats. Through sequential experimentation, let-7d-5p was identified to target LGALS3 and bind to AGO2. In addition, LGALS3 silencing or LPS treatment blocked the TLR4/NF-κB signaling pathway, thereby suppressing intestinal epithelial cell apoptosis and inflammation in NEC. Collectively, let-7d-5p might exercise its inhibitory properties in the inflammatory response and intestinal epithelial cell apoptosis in NEC neonatal rats via inactivation of the LGALS3-dependent TLR4/NF-κB signaling pathway.

Maltodextrin-induced intestinal injury in a neonatal mouse model

Prematurity and enteral feedings are major risk factors for intestinal injury leading to necrotizing enterocolitis (NEC). An immature digestive system can lead to maldigestion of macronutrients and increased vulnerability to intestinal injury. The aim of this study was to test in neonatal mice the effect of maltodextrin, a complex carbohydrate, on the risk of intestinal injury. The goal was to develop a robust and highly reproducible murine model of intestinal injury that allows insight into the pathogenesis and therapeutic interventions of nutrient-driven intestinal injury. Five- to 6-day-old C57BL/6 mice were assigned to the following groups: dam fed (D); D+hypoxia+Klebsiella pneumoniae; maltodextrin-dominant human infant formula (M) only; M+hypoxia; and M+hypoxia+K. pneumoniae. The mice in all M groups were gavage fed five times a day for 4 days. Mice were exposed to hypoxia twice a day for 10 min prior to the first and last feedings, and K. pneumoniae was added to feedings as per group assignment. Mice in all M groups demonstrated reduced body weight, increased small intestinal dilatation and increased intestinal injury scores. Maltodextrin-dominant infant formula with hypoxia led to intestinal injury in neonatal mice accompanied by loss of villi, increased MUC2 production, altered expression of tight junction proteins, enhanced intestinal permeability, increased cell death and higher levels of intestinal inflammatory mediators. This robust and highly reproducible model allows for further interrogation of the effects of nutrients on pathogenic factors leading to intestinal injury and NEC in preterm infants.This article has an associated First Person interview with the first author of the paper.

Biobanking for necrotizing enterocolitis: Needs and standards

BACKGROUND

Necrotizing enterocolitis (NEC) is a devastating gastrointestinal disease that primarily affects premature infants. Despite medical advances, mortality and morbidity from NEC are still unacceptably high. This is partly because of the lack of specific biomarkers and therapies for this disease. Availability of high-quality biological samples and the associated data from premature infants are key to advance our understanding of NEC, and for biomarker discovery and drug development. To that end, the NEC Society Biorepository was established with the goal of promoting studies in human infants through sharing specialized biospecimen and data procurement for NEC research.

OBJECTIVE

In this review, we will discuss the required infrastructure for biobanks, discuss the importance of informatics management, and emphasize the logistical requirements for sharing specimens. Finally, we will discuss the mechanism for how tissues and material will be shared between the institutions.

CONCLUSION

We have developed a state-of-the-art biobank for human infants to advance the field of NEC research. With the NEC Society Biorepository, we seek to facilitate and accelerate the basic and translational studies on NEC to provide hope to the infants afflicted with NEC and their families.

STUDY TYPE

Review article, level V.

Calcium/calmodulin-dependent protein kinase IV signaling pathway is upregulated in experimental necrotizing enterocolitis

PURPOSE

Activation of calcium/calmodulin-dependent protein kinase IV (CaMKIV) has been shown to increase intestinal injury and inhibit epithelial cell proliferation in dextran sulfate sodium (DSS)-induced colitis mice. However, the role of CaMKIV in necrotizing enterocolitis (NEC) is unknown. We aimed to study the expression and activation of CaMKIV in experimental NEC.

METHODS

Following ethical approval, NEC (n = 10) was induced in C57BL/6 mouse pups by hypoxia, gavage hyperosmolar formula feeding and lipopolysaccharide from postnatal days P5 to 9. Breastfed pups served as control (n = 10). Mouse pups were sacrificed on P9 and the terminal ileum was harvested. Gene NEC injury was scored blindly by three independent investigators. CaMKIV, CREM and IL17 gene expression, and CaMKIV and pCaMKIV protein expression were assessed. The data were compared using Mann-Whitney U test. P < 0.05 was considered significant.

RESULTS

Intestinal injury was induced in the NEC mice and confirmed by histological scoring and inflammatory cytokine IL6. CaMKIV and its downstream target genes of CREM and IL17 were significantly elevated in NEC mice relative to control. Similarly, phosphorylated-CaMKIV (pCaMKIV), the active form of CaMKIV, was more notably expressed in the NEC ileal tissue relative to control ileal tissue. Elevated pCaMKIV protein expression was also confirmed by western blot.

CONCLUSION

CaMKIV expression and activation are upregulated in experimental NEC suggesting a potential contributing factor in the pathogenesis of NEC.

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

Necrotizing enterocolitis, a potentially fatal intestinal inflammatory disorder affecting primarily premature infants, is a significant cause of morbidity and mortality in neonates. While the etiology of the disease is, as yet, unknown, a number of risk factors for the development of necrotizing enterocolitis have been identified. One such risk factor, formula feeding, has been shown to contribute to both increased incidence and severity of the disease. The protective influences afforded by breastfeeding are likely attributable to the unique composition of human milk, an extremely potent, biologically active fluid. This review brings together knowledge on the pathogenesis of necrotizing enterocolitis and current thinking on the instrumental role of one of the more prominent classes of bioactive components in human breast milk, glycosaminoglycans.

Vasoactive intestinal peptide decreases inflammation and tight junction disruption in experimental necrotizing enterocolitis

BACKGROUND AND PURPOSE

Excessive inflammatory cell infiltration and accumulation in the intestinal mucosa are pathological features of necrotizing enterocolitis (NEC) leading to intestinal barrier disruption. Vasoactive intestinal peptide (VIP) is a potent anti-inflammatory agent that regulates intestinal epithelial barrier homeostasis. We previously demonstrated that VIP-ergic neuron expression is decreased in experimental NEC ileum, and this may be associated with inflammation and barrier compromise. We hypothesize that exogenous VIP administration has a beneficial effect in NEC.

METHODS

NEC was induced in C57BL/6 mice by gavage feeding, hypoxia, and lipopolysaccharide administration between postnatal day (P) 5 and 9. There were four studied groups: Control (n = 6): Breast feeding without stress factors; Control + VIP (n = 5): Breast feeding + intraperitoneal VIP injection once a day from P5 to P9; NEC (n = 9): mice exposed to NEC induction; NEC + VIP (n = 9): NEC induction + intraperitoneal VIP injection. Terminal ileum was harvested on P9. NEC severity, intestinal inflammation, (IL-6 and TNFα), and Tight junctions (Claudin-3) were evaluated.

RESULTS

NEC severity and intestinal inflammation were significantly decreased in NEC + VIP compared to NEC. Tight junction expression was significantly increased in NEC + VIP compared to NEC.

CONCLUSION

VIP administration has a beneficial therapeutic effect in NEC by reducing inflammation and tight junction disruption.

A Novel Role for Necroptosis in the Pathogenesis of Necrotizing Enterocolitis

BACKGROUND & AIMS

Necrotizing enterocolitis (NEC) is a devastating disease of premature infants characterized by Toll-like receptor 4 (TLR4)-dependent intestinal inflammation and enterocyte death. Given that necroptosis is a proinflammatory cell death process that is linked to bacterial signaling, we investigated its potential role in NEC, and the mechanisms involved.

METHODS

Human and mouse NEC intestine were analyzed for necroptosis gene expression (ie, RIPK1, RIPK3, and MLKL), and protein activation (phosphorylated RIPK3). To evaluate a potential role for necroptosis in NEC, the effects of genetic (ie, Ripk3 knockout or Mlkl knockout) or pharmacologic (ie, Nec1s) inhibition of intestinal inflammation were assessed in a mouse NEC model, and a possible upstream role of TLR4 was assessed in Tlr4-deficient mice. The NEC-protective effects of human breast milk and its constituent milk oligosaccharides on necroptosis were assessed in a NEC-in-a-dish model, in which mouse intestinal organoids were cultured as either undifferentiated or differentiated epithelium in the presence of NEC bacteria and hypoxia.

RESULTS

Necroptosis was activated in the intestines of human and mouse NEC in a TLR4-dependent manner, and was up-regulated specifically in differentiated epithelium of the immature ileum. Inhibition of necroptosis genetically and pharmacologically reduced intestinal-epithelial cell death and mucosal inflammation in experimental NEC, and ex vivo in the NEC-in-a-dish system. Strikingly, the addition of human breast milk, or the human milk oligosaccharide 2 fucosyllactose in the ex vivo system, reduced necroptosis and inflammation.

CONCLUSIONS

Necroptosis is activated in the intestinal epithelium upon TLR4 signaling and is required for NEC development, and explains in part the protective effects of breast milk.

Effects of artificially introduced Enterococcus faecalis strains in experimental necrotizing enterocolitis

Enterococcus faecalis is a ubiquitous intestinal symbiont and common early colonizer of the neonatal gut. Although colonization with E. faecalis has been previously associated with decreased pathology of necrotizing enterocolitis (NEC), these bacteria have been also implicated as opportunistic pathogens. Here we characterized 21 strains of E. faecalis, naturally occurring in 4-day-old rats, for potentially pathogenic properties and ability to colonize the neonatal gut. The strains differed in hemolysis, gelatin liquefaction, antibiotic resistance, biofilm formation, and ability to activate the pro-inflammatory transcription factor NF-κB in cultured enterocytes. Only 3 strains, BB70, 224, and BB24 appreciably colonized the neonatal intestine on day 4 after artificial introduction with the first feeding. The best colonizer, strain BB70, effectively displaced E. faecalis of maternal origin. Whereas BB70 and BB24 significantly increased NEC pathology, strain 224 significantly protected from NEC. Our results show that different strains of E. faecalis may be pathogenic or protective in experimental NEC.

Interleukin 22 disrupts pancreatic function in newborn mice expressing IL-23

Neonatal inflammatory diseases are associated with severe morbidity, but the inflammatory factors underlying them and their potential effector mechanisms are poorly defined. Here we show that necrotizing enterocolitis in neonate mice is accompanied by elevation of IL-23 and IL-22 and decreased production of pancreatic enzymes. These phenotypes are mirrored in neonate mice overexpressing IL-23 in CX3CR1+ myeloid cells or in keratinocytes. The mice fail to grow and die prematurely, displaying systemic inflammation, nutrient malabsorption and decreased expression of intestinal and pancreatic genes mediating digestion and absorption of carbohydrates, proteins, and lipids. Germ-free environment improves, and genetic ablation of IL-22 restores normal growth in mice overexpressing IL-23. Mechanistically, IL-22 acts directly at the level of pancreatic acinar cells to decrease expression of the pancreas associated transcription factor 1a (PTF1a). These results show that augmented production of IL-23 and IL-22 in early life has a negative impact on pancreatic enzyme secretion and food absorption.

A murine neonatal model of necrotizing enterocolitis caused by anemia and red blood cell transfusions

Necrotizing enterocolitis (NEC) is an idiopathic, inflammatory bowel necrosis of premature infants. Clinical studies have linked NEC with antecedent red blood cell (RBC) transfusions, but the underlying mechanisms are unclear. Here we report a neonatal murine model to investigate this association. C57BL/6 mouse pups rendered anemic by timed phlebotomy and then given RBC transfusions develop NEC-like intestinal injury with prominent necrosis, inflammation, and submucosal edema/separation of the lamina propria in the ileocecal region and colon within 12-24 h. The anemic intestine is infiltrated by inflammatory macrophages, which are activated in situ by RBC transfusions via a Toll-like receptor (TLR)-4-mediated mechanism and cause bowel injury. Chelation of RBC degradation products with haptoglobin, absence of TLR4, macrophage depletion, and inhibition of macrophage activation is protective. Intestinal injury worsens with increasing severity and the duration of anemia prior to transfusion, indicating a need for the re-evaluation of current transfusion guidelines for premature infants.

Irf5 deficiency in myeloid cells prevents necrotizing enterocolitis by inhibiting M1 macrophage polarization

Necrotizing enterocolitis (NEC) is a life-threatening inflammatory disease in newborns, but the mechanisms remain unclear. Interferon regulatory factor 5 (IRF5) is a master regulator of macrophage function and is essential for proinflammatory M1 macrophage polarization. Our previous data indicated that M1 macrophages promote NEC injury. Here, we investigated whether IRF5 is involved in the pathogenesis of NEC. First, we found that IRF5 was upregulated in infiltrated macrophages in human neonates with NEC compared to controls. We further confirmed IRF5 upregulation in macrophages in experimental murine NEC and that the infiltrated macrophages were predominantly polarized into the M1 but not the M2 phenotype. Myeloid-specific deficiency of Irf5, which was associated with reduced M1 macrophage polarization and systematic inflammation, dramatically prevented experimental NEC. Moreover, we found that the ablation of Irf5 in myeloid cells markedly suppressed intestinal epithelial cell apoptosis and further prevented intestinal barrier dysfunction in experimental NEC. Bioinformatic and chromatin immunoprecipitation analysis further showed that IRF5 binds to the promoters of the M1 macrophage-associated genes Ccl4, Ccl5, Tnf, and Il12b. Overall, our study provides evidence that IRF5 participates in the pathogenesis of NEC, while the deletion of Irf5 in myeloid cells prevents NEC via inhibiting M1 macrophage polarization.

Blocking NF-κB Activation in Ly6c+ Monocytes Attenuates Necrotizing Enterocolitis

Necrotizing enterocolitis (NEC) is a devastating disease affecting premature infants with intestinal inflammation and necrosis. The neonatal intestinal inflammatory response is rich in macrophages, and blood monocyte count is low in human NEC. We previously found that NF-κB mediates the intestinal injury in experimental NEC. However, the role of NF-κB in myeloid cells during NEC remains unclear. Herein, inhibitor of kappaB kinase β (IKKβ), a critical kinase mediating NF-κB activation, was deleted in lysozyme M (Lysm)-expressing cells, which were found to be Cd11b+Ly6c+ monocytes but not Cd11b+Ly6c- macrophages in the dam-fed neonatal mouse intestine. NEC induced differentiation of monocytes into intestinal macrophages and up-regulation of monocyte recruitment genes (eg, L-selectin) in the macrophage compartment in wild-type mice, but not in pups with IKKβ deletion in Lysm+ cells. Thus, NF-κB is required for NEC-induced monocyte activation, recruitment, and differentiation in neonatal intestines. Furthermore, pups with Lysm-IKKβ deletion had improved survival and decreased incidence of severe NEC compared with littermate controls. Decreased NEC severity was not associated with an improved intestinal barrier. In contrast, NEC was unabated in mice with IKKβ deletion in intestinal epithelial cells. Together, these data suggest that recruitment of Ly6c+ monocytes into the intestine, NF-κB activation in these cells, and differentiation of Ly6c+ monocytes into macrophages are critical cellular and molecular events in NEC development to promote disease.

Bovine milk-derived exosomes enhance goblet cell activity and prevent the development of experimental necrotizing enterocolitis

Necrotizing enterocolitis (NEC) is characterized by intestinal injury and impaired mucin synthesis. We recently showed that breast milk exosomes from rodents promote intestinal cell viability, epithelial proliferation, and stem cell activity, but whether they also affect mucus production is unknown. Therefore, the aim of this study was to investigate the effects of bovine milk-derived exosomes on goblet cell expression in experimental NEC and delineate potential underlying mechanisms of action. Exosomes were isolated from bovine milk by ultracentrifugation and confirmed by Nanoparticle Tracking Analysis and through the detection of exosome membrane markers. To study the effect on mucin production, human colonic LS174T cells were cultured and exposed to exosomes. Compared to control, exosomes promoted goblet cell expression, as demonstrated by increased mucin production and relative expression levels of goblet cell expression markers trefoil factor 3 (TFF3) and mucin 2 (MUC2). In addition, exosome treatment enhanced the expression of glucose-regulated protein 94 (GRP94), the most abundant intraluminal endoplasmic reticulum (ER) chaperone protein that aids in protein synthesis. Furthermore, experimental NEC was induced in mouse pups by hyperosmolar formula feeding, lipopolysaccharide administration and hypoxia exposure on postnatal days 5-9. Milk exosomes were given with each gavage feed. NEC was associated with ileal morphological injury and reduction in MUC2+ goblet cells and GRP94+ cells per villus. Exosome administration to NEC pups prevented these changes. This research highlights the potential novel application of milk-derived exosomes in preventing the development of NEC in high-risk infants when breast milk is not available.

[Pyroptosis is involved in the pathogenesis of necrotizing enterocolitis]

Objective To investigate the role of pyroptosis in the pathogenesis of necrotizing enterocolitis (NEC). Methods Sixty SD rats aged one day were divided into normal control group (n=30) and NEC group (n=30). The NEC model was established in the NEC group by hypoxia and cold stimulation, and the control group was not treated. The general condition of the newborn rats was observed for the first 3 days, and the body mass was measured. On the fourth day, HE staining was used to observe the pathological changes of intestine tissue in the ileocecal area and score them. The levels of IL-18, IL-1β and NLR family pyrin domain containing 3 (NLRP3) in the ileocecal tissues were detected by real-time fluorescent quantitative PCR. The levels of IL-1β and IL-18 in the ileocecal homogenate were tested by ELISA. Western blot analysis was performed to detect the levels of caspase-1, P10 and P20 in the intestinal tissues. Results Compared with the normal group, the neonatal rats in the NEC group were generally in poor condition, and the intestinal epithelial damage in the ileocecal tissue was obvious. The mRNA and protein levels of IL-18 an IL-1β in the intestinal tissues of NEC group and NLRP3 mRNA levels were significantly raised. Caspase-1 protein level was reduced, while P10 and P20 were only expressed in the NEC group. Conclusion Pyroptosis is involved in the pathogenesis of NEC.

Necrotizing Enterocolitis in Moderate Preterm Infants

Necrotizing enterocolitis (NEC) is a devastating morbidity usually seen in preterm infants, with extremely preterm neonates (EPT ≤28 weeks) considered at highest risk. Moderately preterm infants (MPT 28-34 weeks) constitute a large percentage of NICU admissions. In our retrospective data analysis of NEC in a single regional perinatal center, NEC was observed in 10% of extremely EPT and 7% of MPT, but only 0.7% of late-preterm/term admissions. There was an inverse relationship between postnatal age at onset of NEC and gestational age at birth. Among MPT infants with NEC, maternal hypertensive disorders (29%) and small for gestational age (SGA-15%) were more common than in EPT infants (11.6 and 4.6%, resp.). Congenital gastrointestinal anomalies were common among late preterm/term infants with NEC. SGA MPT infants born to mothers with hypertensive disorders are particularly at risk and should be closely monitored for signs of NEC. Identifying risk factors specific to each gestational age may help clinicians to tailor interventions to prevent NEC.

Loss of murine Paneth cell function alters the immature intestinal microbiome and mimics changes seen in neonatal necrotizing enterocolitis

Necrotizing enterocolitis (NEC) remains the leading cause of gastrointestinal morbidity and mortality in premature infants. Human and animal studies suggest a role for Paneth cells in NEC pathogenesis. Paneth cells play critical roles in host-microbial interactions and epithelial homeostasis. The ramifications of eliminating Paneth cell function on the immature host-microbial axis remains incomplete. Paneth cell function was depleted in the immature murine intestine using chemical and genetic models, which resulted in intestinal injury consistent with NEC. Paneth cell depletion was confirmed using histology, electron microscopy, flow cytometry, and real time RT-PCR. Cecal samples were analyzed at various time points to determine the effects of Paneth cell depletion with and without Klebsiella gavage on the microbiome. Deficient Paneth cell function induced significant compositional changes in the cecal microbiome with a significant increase in Enterobacteriacae species. Further, the bloom of Enterobacteriaceae species that occurs is phenotypically similar to what is seen in human NEC. This further strengthens our understanding of the importance of Paneth cells to intestinal homeostasis in the immature intestine.

Enteral administration of bacteria fermented formula in newborn piglets: A high fidelity model for necrotizing enterocolitis (NEC)

Objective

To develop an animal model which replicates neonatal NEC and characterizes the importance of bacterial fermentation of formula and short chain fatty acids (SCFAs) in its pathogenesis.

Background

NEC is a severe form of intestinal inflammation in preterm neonates and current models do not reproduce the human condition.

Methods

Three groups of newborn piglets: Formula alone (FO), Bacteria alone (E.coli: BO) and E.coli-fermented formula (FF) were anesthetized, instrumented and underwent post-pyloric injection of formula, bacteria or fermented-formula. SCFA levels were measured by gas chromatography-mass spectrometry. At 6 h bowel appearance was assessed, histologic and molecular analysis of intestine were performed. Gut inflammation (p65 NF-κB, TLR4, TNF-α, IL-1β), apoptosis (cleaved caspase-3, BAX, apoptosis) and tight junction proteins (claudin-2, occludin) were measured.

Results

SCFAs were increased in FF. Small bowel from FF piglet’s demonstrated inflammation, coagulative necrosis and pneumatosis resembling human NEC. Histologic gut injury (injury score, mast cell activation) were increased by Bacteria, but more severe in FF piglets. Intestinal expression of p65 NF-κB, NF-κB activation, TNF-α and IL-1β were increased in BO and markedly increased in the FF group (P<0.05 vs. FO). Intestine from Bacteria piglets demonstrated increased apoptotic index, pro-apoptotic protein expression and decreased tight junction proteins. These changes were more severe in FF piglets.

Conclusions

Our piglet model demonstrates the findings of NEC in human neonates: systemic acidosis, intestinal inflammation, pneumatosis and portal venous gas. Bacteria alone can initiate intestinal inflammation, injury and apoptosis, but bacterial fermentation of formula generates SCFAs which contribute to the pathogenesis of NEC.

Lactobacillus murinus HF12 colonizes neonatal gut and protects rats from necrotizing enterocolitis

The use of lactobacilli in prevention of necrotizing enterocolitis (NEC) is hampered by insufficient knowledge about optimal species/strains and effects on intestinal bacterial populations. We therefore sought to identify lactobacilli naturally occurring in postnatal rats and examine their ability to colonize the neonatal intestine and protect from NEC. L. murinus, L. acidophilus, and L. johnsonii were found in 42, 20, and 1 out of 51 4-day old rats, respectively. Higher proportion of L. murinus in microbiota correlated with lower NEC scores. Inoculation with each of the three species during first feeding significantly augmented intestinal populations of lactobacilli four days later, indicating successful colonization. L. murinus, but not L. acidophilus or L. johnsonii, significantly protected against NEC. Thus, lactobacilli protect rats from NEC in a species- or strain-specific manner. Our results may help rationalizing probiotic therapy in NEC.

Soybean-derived recombinant human epidermal growth factor protects against experimental necrotizing enterocolitis

BACKGROUND

Epidermal Growth Factor (EGF) reduces necrotizing enterocolitis (NEC). However, its high cost virtually prohibits clinical use. To reduce cost, soybean expressing human EGF was developed. Here we report effectiveness of soybean-derived EGF in experimental NEC.

METHODS

Newborn rats were subjected to the NEC-inducing regimen of formula feeding and hypoxia. Formula was supplemented with extract from EGF-expressing or empty soybeans. NEC pathology was determined microscopically. Localization of tight junction proteins JAM-A and ZO-1 was examined by immunofluorescence and levels of mucosal COX-2 and iNOS mRNAs by real time PCR.

RESULTS

Soybean extract amounts corresponding to 150μg/kg/day EGF caused considerable mortality, whereas those corresponding to 75μg/kg/day EGF were well tolerated. There was no significant difference in NEC scores between animals fed plain formula and formula supplemented with empty soybean extract. Soybean-EGF-supplemented formula at 75μg/kg/day EGF significantly decreased NEC, attenuated dissociation of JAM-A and ZO-1 proteins from tight junctions, and reduced intestinal expression of COX-2 and iNOS mRNAs.

CONCLUSION

Supplementation with soybean-expressed EGF significantly decreased NEC in the rat model. Soybean-expressed EGF may provide an economical solution for EGF administration and prophylaxis of clinical NEC.