Pathogenesis of NEC: Role of the innate and adaptive immune response

Applying the bronchopulmonary dysplasia framework to necrotizing enterocolitis

Necrotizing enterocolitis (NEC) is a devastating disease of the neonatal intestine, causing widespread intestinal necrosis as well systemic illness that frequently results in death. Because the clinical onset of NEC is sudden and difficult to predict, NEC is considered an acute event. However, NEC does not occur in utero, meaning that postnatal exposures are required, and it does not typically occur right after birth, suggesting that longitudinal changes may be occurring before NEC can develop. In this perspective, the author considers whether NEC should be re-considered as a problem of disordered intestinal epithelial development, with required maladaptation over time prior to the onset of the necrotic event. This framework is similar to how bronchopulmonary dysplasia is currently conceptualized. They also advocate that NEC researchers incorporate this possibility into future studies on NEC susceptibility and pathogenesis.

Values of serum intestinal fatty acid-binding protein, fecal calprotectin, and fecal human β-defensin 2 for predicting necrotizing enterocolitis

BACKGROUND

This study aimed to assess the diagnostic potential of serum intestinal fatty acid-binding protein (I-FABP), fecal calprotectin (FC), and fecal human β-defensin 2 (hBD2) in predicting necrotizing enterocolitis (NEC) in preterm infants.

METHODS

A prospective cohort of neonates with a gestational age < 32 weeks, suspected of NEC, was enrolled between June 2021 and December 2022. Serum I-FABP, FC, and fecal hBD2 levels were measured upon NEC suspicion, and diagnosis was confirmed through radiological examination or surgical intervention. Diagnostic precision of serum I-FABP, FC, and fecal hBD2 was assessed using a logistic regression model with multiple variables.

RESULTS

The study included 70 neonates (45 males, 25 females), with 30 developing NEC (40% Stage III, n = 12; 60% Stage II, n = 18) and 40 in the control group. NEC patients exhibited significantly higher serum I-FABP and FC levels (4.76 ng/mL and 521.56 µg/g feces, respectively) than those with other diagnoses (1.38 ng/mL and 213.34 µg/g feces, respectively; p ˂ 0.05 for both biomarkers). Stage II NEC neonates showed elevated fecal hBD2 levels (376.44 ng/g feces) than Stage III NEC neonates and controls (336.87 ng/g and 339.86 ng/g feces, respectively; p ˂ 0.05). No such increase was observed in infants progressing to Stage III NEC. Using a serum I-FABP threshold of > 2.54 ng/mL yielded 76.7% sensitivity, 87.5% specificity, 82.1% positive predictive value (PPV), and 83.3% negative predictive value (NPV). For FC (cutoff > 428.99 µg/g feces), corresponding values were 76.7% sensitivity, 67.5% specificity, 63.9% PPV, and 79.4% NPV.

CONCLUSION

Serum I-FABP and FC levels are valuable for early NEC detection and provide insights into disease severity. Low fecal hBD2 levels suggest an inadequate response to luminal bacteria, potentially rendering these infants more susceptible to NEC development or exacerbation.

Dietary fiber pectin: challenges and potential anti-inflammatory benefits for preterms and newborns

Pectins, a class of dietary fibers abundant in vegetables and fruits, have drawn considerable interest due to their potential anti-inflammatory properties. Numerous studies have indicated that incorporating pectins into infant formula could be a safe strategy for alleviating infant regurgitation and diarrhea. Moreover, pectins have been shown to modulate cytokine production, macrophage activity, and NF-kB expression, all contributing to their anti-inflammatory effects. Despite this promising evidence, the exact mechanisms through which pectins exert these functions and how their structural characteristics influence these processes remain largely unexplored. This knowledge is particularly significant in the context of gut inflammation in developing preterm babies, a critical aspect of necrotizing enterocolitis (NEC), and in children and adults dealing with inflammatory bowel disease (IBD). Our mini review aims to provide an up-to-date compilation of relevant research on the effects of pectin on gut immune responses, specifically focusing on preterms and newborns. By shedding light on the underlying mechanisms and implications of pectin-mediated anti-inflammatory properties, this review seeks to advance our knowledge in this area and pave the way for future research and potential therapeutic interventions.

Hydrogen Sulfide Improves Outcomes in a Murine Model of Necrotizing Enterocolitis via the Cys440 Residue on Endothelial Nitric Oxide Synthase

BACKGROUND

Hydrogen sulfide (H2S) has been shown to improve outcomes in a murine model of necrotizing enterocolitis (NEC). There is evidence in humans that H2S relies on endothelial nitric oxide synthase (eNOS) to exert its protective effects, potentially through the persulfidation of eNOS at the Cysteine 443 residue. We obtained a novel mouse strain with a mutation at this residue (eNOSC440G) and hypothesized that this locus would be critical for GYY4137 (an H2S donor) to exert its protective effects.

METHODS

Necrotizing enterocolitis was induced in 5-day old wild type (WT) and eNOSC440G mice using intermittent exposure to hypoxia and hypothermia in addition to gavage formula feeds. On postnatal day 9, mice were humanely euthanized. Data collected included daily weights, clinical sickness scores, histologic lung injury, intestinal injury (macroscopically and histologically), and intestinal perfusion. During the NEC model, pups received daily intraperitoneal injections of either GYY4137 (50 mg/kg) or PBS (vehicle). Data were tested for normality and compared using t-test or Mann-Whitney, and a p-value <0.05 was considered significant.

RESULTS

In WT mice, the administration of GYY4137 significantly improved clinical sickness scores, attenuated intestinal and lung injury, and improved mesenteric perfusion compared to vehicle (p < 0.05). In eNOSC440G mice, the treatment and vehicle groups had similar clinical sickness scores, intestinal and lung injury scores, and intestinal perfusion.

CONCLUSIONS

GYY4137 administration improves clinical outcomes, attenuates intestinal and lung injury, and improves perfusion in a murine model of necrotizing enterocolitis. The beneficial effects of GYY4137 are dependent on the Cys440 residue of eNOS.

Identification of omega-3 oxylipins in human milk-derived extracellular vesicles with pro-resolutive actions in gastrointestinal inflammation

Introduction

Premature infants (PIs) are at risk of suffering necrotizing enterocolitis (NEC), and infants consuming human milk (HM) show a lower incidence than infants receiving formula. The composition of HM has been studied in depth, but the lipid content of HM-derived small extracellular vesicles (HM sEVs) remains unexplored. Identifying these molecules and their biological effects has potential for the treatment of intestinal disorders in PIs and could contribute to the development of HM-based fortified formulas.

Methods

We isolated HM sEVs from HM samples and analyzed their oxylipin content using liquid chromatography coupled to mass spectrometry, which revealed the presence of anti-inflammatory oxylipins. We then examined the efficacy of a mixture of these oxylipins in combating inflammation and fibrosis, in vitro and in a murine model of inflammatory bowel disease (IBD).

Results

HM-related sEVs contained higher concentrations of oxylipins derived from docosahexaenoic acid, an omega-3 fatty acid. Three anti-inflammatory oxylipins, 14-HDHA, 17-HDHA, and 19,20-DiHDPA (ω3 OXLP), demonstrated similar efficacy to HM sEVs in preventing cell injury, inducing re-epithelialization, mitigating fibrosis, and modulating immune responses. Both ω3 OXLP and HM sEVs effectively reduced inflammation in IBD-model mice, preventing colon shortening, infiltration of inflammatory cells and tissue fibrosis.

Discussion

Incorporating this unique cocktail of oxylipins into fortified milk formulas might reduce the risk of NEC in PIs and also provide immunological and neurodevelopmental support.

To What Extent Does Arginine Reduce the Risk of Developing Necrotizing Enterocolitis?

Necrotizing enterocolitis (NEC) and neonatal sepsis are polar opposite diseases that are commonly encountered in the NICU. Concerning the frequency of these pathologies, NEC is regarded as being a much rarer condition, whereas neonatal sepsis is slightly more commonly encountered. However, neonatal sepsis can present with varying clinical presentations and, if caught late, can be detrimental to the patient. Many different modes of therapies have been studied for both conditions at different levels of pathologies, from a microscopic to a macroscopic level, leading to an assessment of treatment approaches. With the different ongoing treatment protocols being studied, one such therapy under investigation that does stand out is the use of L-arginine in both conditions. The L-arginine, being an essential amino acid, has many basic biological roles in developing neonates. It mainly involves the production of nitric oxide (NO), a potent vasodilator, which is particularly important in the development of vasculature in almost every organ. In premature infants, poorly developed vasculature makes them more susceptible to injury, therefore increasing the risk of diseases such as NEC and the severity of diseases such as neonatal sepsis. By assessing the uses of L-arginine and its application towards treating conditions like NEC and neonatal sepsis, we aim to identify its potential benefits as a treatment and its potential applications in clinical practice by understanding its basic functions and role in the pathophysiology of NEC and neonatal sepsis.

The Association of Human Milk Proportion with the Clinical Outcomes of Necrotizing Enterocolitis in Preterm Infants: A Retrospective Study

Human milk (HM) has been associated with a lower risk of necrotizing enterocolitis (NEC). However, the association of precise HM proportion with the outcome of NEC remains unclear. A total of 77 cases and 154 matched controls were included in this study. The samples were divided into three groups based on the HM proportion of the total enteral intake before NEC onset: ≥70% (HHM), <70% (LHM), and 0% (NHM). The study cohort did not show a significant association between different HM proportions and NEC risk. The adjusted odds ratio (OR) for the highest versus the lowest intake was 0.599. In the prognosis of NEC, different HM proportions significantly affected weight gain, the timing of NEC onset, diagnosis time, hospitalization cost, and the severity of NEC (p < 0.05). Our findings support the beneficial effects of HM on reducing NEC in preterm infants, particularly when a greater proportion of HM of the total enteral intake is included in their feeding. Additionally, the study indicates that preterm infants fed with lower proportions of HM of the total enteral feeding are more prone to experiencing severe cases of NEC.

Progress in Research on Stem Cells in Neonatal Refractory Diseases

With the development and progress of medical technology, the survival rate of premature and low-birth-weight infants has increased, as has the incidence of a variety of neonatal diseases, such as hypoxic-ischemic encephalopathy, intraventricular hemorrhage, bronchopulmonary dysplasia, necrotizing enterocolitis, and retinopathy of prematurity. These diseases cause severe health conditions with poor prognoses, and existing control methods are ineffective for such diseases. Stem cells are a special type of cells with self-renewal and differentiation potential, and their mechanisms mainly include anti-inflammatory and anti-apoptotic properties, reducing oxidative stress, and boosting regeneration. Their paracrine effects can affect the microenvironment in which they survive, thereby affecting the biological characteristics of other cells. Due to their unique abilities, stem cells have been used in treating various diseases. Therefore, stem cell therapy may open up the possibility of treating such neonatal diseases. This review summarizes the research progress on stem cells and exosomes derived from stem cells in neonatal refractory diseases to provide new insights for most researchers and clinicians regarding future treatments. In addition, the current challenges and perspectives in stem cell therapy are discussed.

Programmed death of intestinal epithelial cells in neonatal necrotizing enterocolitis: a mini-review

Necrotizing enterocolitis (NEC) is one of the most fatal diseases in premature infants. Damage to the intestinal epithelial barrier (IEB) is an important event in the development of intestinal inflammation and the evolution of NEC. The intestinal epithelial monolayer formed by the tight arrangement of intestinal epithelial cells (IECs) constitutes the functional IEB between the organism and the extra-intestinal environment. Programmed death and regenerative repair of IECs are important physiological processes to maintain the integrity of IEB function in response to microbial invasion. However, excessive programmed death of IECs leads to increased intestinal permeability and IEB dysfunction. Therefore, one of the most fundamental questions in the field of NEC research is to reveal the pathological death process of IECs, which is essential to clarify the pathogenesis of NEC. This review focuses on the currently known death modes of IECs in NEC mainly including apoptosis, necroptosis, pyroptosis, ferroptosis, and abnormal autophagy. Furthermore, we elaborate on the prospect of targeting IECs death as a treatment for NEC based on exciting animal and clinical studies.

Single-cell atlas of the human neonatal small intestine affected by necrotizing enterocolitis

Necrotizing enterocolitis (NEC) is a gastrointestinal complication of premature infants with high rates of morbidity and mortality. A comprehensive view of the cellular changes and aberrant interactions that underlie NEC is lacking. This study aimed at filling in this gap. We combine single-cell RNA sequencing (scRNAseq), T-cell receptor beta (TCRβ) analysis, bulk transcriptomics, and imaging to characterize cell identities, interactions, and zonal changes in NEC. We find an abundance of proinflammatory macrophages, fibroblasts, endothelial cells as well as T cells that exhibit increased TCRβ clonal expansion. Villus tip epithelial cells are reduced in NEC and the remaining epithelial cells up-regulate proinflammatory genes. We establish a detailed map of aberrant epithelial-mesenchymal-immune interactions that are associated with inflammation in NEC mucosa. Our analyses highlight the cellular dysregulations of NEC-associated intestinal tissue and identify potential targets for biomarker discovery and therapeutics.

Single-cell RNA sequencing of intestinal immune cells in neonatal necrotizing enterocolitis

PURPOSE

Necrotizing enterocolitis (NEC) causes fatal intestinal necrosis in neonates, but its etiology is unknown. We analyzed the intestinal immune response to NEC.

METHODS

Using single-cell RNA sequencing (scRNA-seq), we analyzed the gene expression profiles of intestinal immune cells from four neonates with intestinal perforation (two with NEC and two without NEC). Target mononuclear cells were extracted from the lamina propria of the resected intestines.

RESULTS

In all four cases, major immune cells, such as T cells (15.1-47.7%), B cells (3.1-19.0%), monocytes (16.5-31.2%), macrophages (1.6-17.4%), dendritic cells (2.4-12.2%), and natural killer cells (7.5-12.8%), were present in similar proportions to those in the neonatal cord blood. Gene set enrichment analysis showed that the MTOR, TNF-α, and MYC signaling pathways were enriched in T cells of the NEC patients, suggesting upregulated immune responses related to inflammation and cell proliferation. In addition, all four cases exhibited a bias toward cell-mediated inflammation, based on the predominance of T helper 1 cells.

CONCLUSION

Intestinal immunity in NEC subjects exhibited stronger inflammatory responses compared to non-NEC subjects. Further scRNA-seq and cellular analysis may improve our understanding of the pathogenesis of NEC.

Paneth cell proteins DEFA6 and GUCA2A as tissue markers in necrotizing enterocolitis

Previous studies suggest that Paneth cells are involved in NEC development. Defensin alpha 6 (DEFA6) and guanylate cyclase activator 2A (GUCA2A) are selective protein markers of Paneth cells. The objective was to explore DEFA6 and GUCA2A expression in intestinal tissue samples from newborn infants with and without NEC. Tissue samples from histologically intact intestine were analyzed from 70 infants: 43 underwent bowel resection due to NEC and 27 controls were operated due to conditions such as intestinal atresia, dysmotility, aganglionosis, pseudo-obstruction or volvulus. Each tissue sample was immunohistochemically stained for DEFA6 and GUCA2A. Semi-automated digital image analysis was performed to determine protein expression. Clinical data and protein expressions were compared between the groups. DEFA6 expression was lower in the NEC group (p = 0.006). Low DEFA6 correlated with risk of developing NEC in a logistic regression analysis, independently of gestational age and birth weight (OR 0.843 [CI 0.732-0.971]; p = 0.018). GUCA2A expression did not differ between the two groups.

CONCLUSION

Lower expression of DEFA6 together with intact GUCA2A expression indicates that NEC patients have well-defined Paneth cells but diminished defensin activity. Our results suggest that DEFA6 could be used as a biomarker for NEC.

WHAT IS KNOWN

• Previous studies of defensin activity in NEC have been inconsistent, showing that defensin levels may be increased or diminished in NEC. GUCA2A has to our knowledge never been studied in NEC.

WHAT IS NEW

• This study benchmarks two specific Paneth cell markers (DEFA6 and GUCA2A) and their activity in individuals with and without NEC. • The key finding is that the NEC group had a lower DEFA6 expression compared to the Controls, while the expression of GUCA2A did not differ between the groups.

Harnessing the therapeutic potential of the stem cell secretome in neonatal diseases

Preterm birth and intrapartum related complications account for a substantial amount of mortality and morbidity in the neonatal period despite significant advancements in neonatal-perinatal care. Currently, there is a noticeable lack of curative or preventative therapies available for any of the most common complications of prematurity including bronchopulmonary dysplasia, necrotizing enterocolitis, intraventricular hemorrhage, periventricular leukomalacia and retinopathy of prematurity or hypoxic-ischemic encephalopathy, the main cause of perinatal brain injury in term infants. Mesenchymal stem/stromal cell-derived therapy has been an active area of investigation for the past decade and has demonstrated encouraging results in multiple experimental models of neonatal disease. It is now widely acknowledged that mesenchymal stem/stromal cells exert their therapeutic effects via their secretome, with the principal vector identified as extracellular vesicles. This review will focus on summarizing the current literature and investigations on mesenchymal stem/stromal cell-derived extracellular vesicles as a treatment for neonatal diseases and examine the considerations to their application in the clinical setting.

Butyrate induces development-dependent necrotizing enterocolitis-like intestinal epithelial injury via necroptosis

BACKGROUND

The accumulation of short-chain fatty acids (SCFAs) from bacterial fermentation may adversely affect the under-developed gut as observed in premature newborns at risk for necrotizing enterocolitis (NEC). This study explores the mechanism by which specific SCFA fermentation products may injure the premature newborn intestine mucosa leading to NEC-like intestinal cell injury.

METHODS

Intraluminal injections of sodium butyrate were administered to 14- and 28-day-old mice, whose small intestine and stool were harvested for analysis. Human intestinal epithelial stem cells (hIESCs) and differentiated enterocytes from preterm and term infants were treated with sodium butyrate at varying concentrations. Necrosulfonamide (NSA) and necrostatin-1 (Nec-1) were used to determine the protective effects of necroptosis inhibitors on butyrate-induced cell injury.

RESULTS

The more severe intestinal epithelial injury was observed in younger mice upon exposure to butyrate (p = 0.02). Enterocytes from preterm newborns demonstrated a significant increase in sensitivity to butyrate-induced cell injury compared to term newborn enterocytes (p = 0.068, hIESCs; p = 0.038, differentiated cells). NSA and Nec-1 significantly inhibited the cell death induced by butyrate.

CONCLUSIONS

Butyrate induces developmental stage-dependent intestinal injury that resembles NEC. A primary mechanism of cell injury in NEC is necroptosis. Necroptosis inhibition may represent a potential preventive or therapeutic strategy for NEC.

IMPACT

Butyrate induces developmental stage-dependent intestinal injury that resembles NEC. A primary mechanism of cell injury caused by butyrate in NEC is necroptosis. Necroptosis inhibitors proved effective at significantly ameliorating the enteral toxicity of butyrate and thereby suggest a novel mechanism and approach to the prevention and treatment of NEC in premature newborns.

Extracellular Vesicle-microRNAs as Diagnostic Biomarkers in Preterm Neonates

Neonates born prematurely (<37 weeks of gestation) are at a significantly increased risk of developing inflammatory conditions associated with high mortality rates, including necrotizing enterocolitis, bronchopulmonary dysplasia, and hypoxic-ischemic brain damage. Recently, research has focused on characterizing the content of extracellular vesicles (EVs), particularly microRNAs (miRNAs), for diagnostic use. Here, we describe the most recent work on EVs-miRNAs biomarkers discovery for conditions that commonly affect premature neonates.

Intra-Amniotic Administration-An Emerging Method to Investigate Necrotizing Enterocolitis, In Vivo (Gallus gallus)

Necrotizing enterocolitis (NEC) is a severe gastrointestinal disease in premature infants and a leading cause of death in neonates (1-7% in the US). NEC is caused by opportunistic bacteria, which cause gut dysbiosis and inflammation and ultimately result in intestinal necrosis. Previous studies have utilized the rodent and pig models to mimic NEC, whereas the current study uses the in vivo (Gallus gallus) intra-amniotic administration approach to investigate NEC. On incubation day 17, broiler chicken (Gallus gallus) viable embryos were injected intra-amniotically with 1 mL dextran sodium sulfate (DSS) in H₂O. Four treatment groups (0.1%, 0.25%, 0.5%, and 0.75% DSS) and two controls (H₂O/non-injected controls) were administered. We observed a significant increase in intestinal permeability and negative intestinal morphological changes, specifically, decreased villus surface area and goblet cell diameter in the 0.50% and 0.75% DSS groups. Furthermore, there was a significant increase in pathogenic bacterial (E. coli spp. and Klebsiella spp.) abundances in the 0.75% DSS group compared to the control groups, demonstrating cecal microbiota dysbiosis. These results demonstrate significant physiopathology of NEC and negative bacterial-host interactions within a premature gastrointestinal system. Our present study demonstrates a novel model of NEC through intra-amniotic administration to study the effects of NEC on intestinal functionality, morphology, and gut microbiota in vivo.

The Immunological Role of Milk Fat Globule Membrane

Human milk is the ideal food for newborns until the age of six months. Human milk can be defined as a dynamic living tissue, containing immunological molecules, such as immunoglobulins, supra-molecular structures, such as the milk fat globule membrane (MFGM), and even entire cells, such as the milk microbiota. The milk composition changes throughout lactation to fulfill the infant’s requirements and reflect the healthy/disease status of the lactating mother. Many bioactive milk components are either soluble or bound to the MFGM. In this work, we focus on the peculiar role of the MFGM components, from their structural organization in fat globules to their route into the gastrointestinal tract. Immunometabolic differences between human and bovine MFGM components are reported and the advantages of supplementing infant formula with the MFGM are highlighted.

Human Breast Milk: The Key Role in the Maturation of Immune, Gastrointestinal and Central Nervous Systems: A Narrative Review

Premature birth is a major cause of mortality and morbidity in the pediatric population. Because their immune, gastrointestinal and nervous systems are not fully developed, preterm infants (<37 weeks of gestation) and especially very preterm infants (VPIs, <32 weeks of gestation) are more prone to infectious diseases, tissue damage and future neurodevelopmental impairment. The aim of this narrative review is to report the immaturity of VPI systems and examine the role of Human Breast Milk (HBM) in their development and protection against infectious diseases, inflammation and tissue damage. For this purpose, we searched and synthesized the data from the existing literature published in the English language. Studies revealed the significance of HBM and indicate HBM as the best dietary choice for VPIs.

Initial surgical treatment of necrotizing enterocolitis: a meta-analysis of peritoneal drainage versus laparotomy

Necrotizing enterocolitis (NEC) in premature infants is associated with high morbidity and mortality, and the optimal intervention remains uncertain. To compare the mortality of primary peritoneal drainage versus primary peritoneal laparotomy as initial surgical intervention for NEC. All data were extracted from PubMed, Embase, and the Cochrane Library. Studies published up to December 2021. Patients with NEC. Studies centered on primary peritoneal drainage and primary peritoneal laparotomy as the initial surgical treatment. Mortality outcomes were available for both interventions. Randomized controlled trials, retrospective cohort studies, and case series in peer-reviewed journals. Language limited to English. Odds ratio (OR) with 95% confidence intervals (CIs) was used to evaluate mortality outcome. Subgroup analyses and linear regression were performed to ascertain the association between mortality pre-specified factors. Data of 1062 patients received peritoneal drainage and 2185 patients received peritoneal laparotomy from five case series, five retrospective cohort studies, and three randomized controlled trials. Peritoneal drainage caused similar mortality (OR 1.49, 95% CI 0.99-2.26) compared with peritoneal laparotomy as initial surgical management for NEC infants. The subgroup analysis of study design, sample size, birth weight, and sex showed similar findings, but inconsistent results were found for country (USA: 1.47, 95% CI 0.90-2.41; Canada: 2.53, 95% CI 0.30-21.48; Australia: 10.29, 95% CI 1.03-102.75; Turkey: 0.09, 95% CI 0.01-0.63) and gestational age (age mean difference < 3: 1.23, 95% CI 0.72-2.11; age mean difference ≥ 3: 2.29, 95% CI 1.04-5.05). No statistically significance was found for the linear regression between mortality and sample size (P = 0.842), gestational age (P = 0.287), birth weight (P = 0.257), sex (P = 0.6). Small sample size, high heterogeneity, NEC, and spontaneous intestinal perforation (SIP) had to be analyzed together, lack of selection criteria for the future selection of an intervention, and no clear, standardized procedures.   Conclusion: There was no significant difference in mortality between peritoneal drainage and laparotomy as initial surgical intervention. The results suggest that either intervention could be used in selected patients. What is Known: • Necrotizing enterocolitis (NEC) in premature infants is associated with high morbidity and mortality, and the optimal intervention remains uncertain. What is New: • No significant difference of mortality between peritoneal drainage and laparotomy as initial surgical intervention.

Advances in our understanding of the molecular pathogenesis of necrotizing enterocolitis

Necrotizing enterocolitis (NEC) is a multifactorial and complex disease. Our knowledge of the cellular and genetic basis of NEC have expanded considerably as new molecular mechanisms have been identified. This article will focus on the current understanding of the molecular pathogenesis of NEC with a focus on the inflammatory, immune, infectious, and genetic mechanisms that drive disease development.

Hyaluronic Acid 35 kDa Protects against a Hyperosmotic, Formula Feeding Model of Necrotizing Enterocolitis

Necrotizing enterocolitis (NEC), an inflammatory disease of the intestine, is a common gastrointestinal emergency among preterm infants. Intestinal barrier dysfunction, hyperactivation of the premature immune system, and dysbiosis are thought to play major roles in the disease. Human milk (HM) is protective, but the mechanisms underpinning formula feeding as a risk factor in the development of NEC are incompletely understood. Hyaluronic acid 35 kDa (HA35), a bioactive glycosaminoglycan of HM, accelerates intestinal development in murine pups during homeostasis. In addition, HA35 prevents inflammation-induced tissue damage in pups subjected to murine NEC, incorporating Paneth cell dysfunction and dysbiosis. We hypothesized HA35 treatment would reduce histological injury and mortality in a secondary mouse model of NEC incorporating formula feeding. NEC-like injury was induced in 14-day mice by dithizone-induced disruption of Paneth cells and oral gavage of rodent milk substitute. Mortality and histological injury, serum and tissue cytokine levels, stool bacterial sequencing, and bulk RNA-Seq comparisons were analyzed. HA35 significantly reduced the severity of illness in this model, with a trend toward reduced mortality, while RNA-Seq analysis demonstrated HA35 upregulated genes associated with goblet cell function and innate immunity. Activation of these critical protective and reparative mechanisms of the small intestine likely play a role in the reduced pathology and enhanced survival trends of HA-treated pups subjected to intestinal inflammation in this secondary model of NEC, providing potentially interesting translational targets for the human preterm disease.

Intestinal perfusion assessed by quantitative fluorescence angiography in piglets with necrotizing enterocolitis

BACKGROUND

Reduced intestinal perfusion is thought to be a part of the pathogenesis in necrotizing enterocolitis (NEC). This study aims to evaluate the intestinal perfusion assessment in NEC-lesions by quantitative fluorescence angiography with indocyanine green (q-ICG) during laparoscopy and open surgery.

METHODS

Thirty-four premature piglets were delivered by cesarean section and fed with parenteral nutrition and increasing infant formula volumes to induce NEC. During surgery, macroscopic NEC-lesions were evaluated using a validated macroscopic scoring system (1-6 for increasing NEC severity). The intestinal perfusion was assessed by q-ICG and quantified with a validated pixel intensity computer algorithm.

RESULTS

Significantly higher perfusion values were found in healthy areas of the colon (score 1) compared to those with NEC scores of 4, 5, and 6 (p < 0.05). Similarly, in the small intestine, perfusion was higher in the intestine with areas scored 1 compared to scores of 3 and 4 (p < 0.05). A cut-off value was found between NEC score of 1-2 vs. 3-4 for the small intestine at 117 and for colon at 107 between NEC scores 12 vs. scores of 36 with an area less than the curve value at 0.9 (p < 0.05).

CONCLUSIONS

q-ICG seems to be a feasible and valuable technique to evaluate the perfusion of tissue with NEC-lesions. We found a cut-off between intestine with scores 1-2 and intestine with NEC scores 3-6 in colon, and NEC score 3-4 in the small intestine.

LEVEL OF EVIDENCE

II.

DMBT1 expression and neutrophil-to-lymphocyte ratio during necrotizing enterocolitis are influenced by impaired perfusion due to cardiac anomalies

BACKGROUND

Deleted in malignant brain tumors 1 (DMBT1) is involved in innate immunity and epithelial differentiation. It has been proven to play a role in various states of inflammation or hypoxia of fetal gastrointestinal and pulmonary diseases. Discrimination of pathogenesis in necrotizing enterocolitis (NEC) based on cardiac status improves the understanding of NEC in different patient subgroups. We aimed at examining DMBT1 expressions regarding their association with cardiac status leading to impaired intestinal perfusion, intraoperative bacteria proof, and a fulminant course of NEC.

METHODS

Twenty-eight patients with NEC were treated surgically between 2010 and 2019 at our institution. DMBT1 expression was examined in intestinal sections using immunohistochemistry to detect DMBT1 protein. Associations of clinical parameters and DMBT1 expression were analyzed.

RESULTS

We examined DMBT1 levels in 10 patients without cardiac defects and 18 patients with persisting ductus arteriosus (PDA) and congenital heart defects (CHD). Compared to patients without cardiac malformations, DMBT1 levels tended to score higher in patients with PDA/CHD (p = 0.2113) and were negatively correlated with C-reactive protein in these infants (p = 0.0172; r = - 0.5533). The number of DMBT1-expressing macrophages was elevated in the PDA/CHD-subgroup (p = 0.0399). Ratios of neutrophils and monocytes to lymphocytes were significantly higher in infants with PDA/CHD (p = 0.0319 and 0.0493). DMBT1 expression was significantly associated with positive bacterial culture of intraoperative swabs (p = 0.0252) and DMBT1 expression of the serosa was associated with a fulminant course of NEC (p = 0.0239).

CONCLUSIONS

This study demonstrates that DMBT1 expression may be influenced by cardiac anomalies with an impaired intestinal perfusion in the neonatal intestine. NEC in PDA/CHD infants is associated with more DMBT1-positive macrophages and a significantly elevated neutrophil-to-lymphocyte ratio.

Correlation of systemic immune-inflammation Index with surgical necrotizing enterocolitis

BACKGROUND

Systemic Immune-Inflammation Index (SII), known as an easy, economical and useful marker, correlates with the severity of inflammatory response. However, the usefulness of SII in necrotizing enterocolitis (NEC) remains unclear. Therefore, we evaluated the correlation of SII at NEC diagnosis and subsequent surgery.

METHODS

Retrospective review of 131 neonates with NEC in a tertiary-level pediatric referral hospital was conducted with assessments of demographic data, general blood examination results at NEC diagnosis, treatment strategies and clinical outcomes. The receiver operating characteristic (ROC) curve determined the optimal cut-off values of SII, platelet-to-lymphocyte ratio (PLR), and neutrophil-to-lymphocyte ratio. Univariate/multivariate logistic regression analysis and ROC curve were conducted to evaluate the predictive significance of SII in identifying the patients who eventually received surgery. Additionally, NEC-related deaths were assessed.

RESULTS

Overall, 49 (37.4%) cases received surgical intervention and mortality was 12.3% (14/131). The area under ROC curve of SII at NEC diagnosis to predict subsequent surgery was 0.833 (optimal cut-off value: 235.85). The SII value in surgical intervention group was significantly higher than that in medical treatment group (332.92 ± 158.52 vs. 158.84 ± 106.82, P < 0.001). Independent influencing factors for surgical NEC were SII (95% confidence interval [CI]: 4.568∼36.449, odds ratio [OR]:12.904, P < 0.001) and PLR (95% CI: 1.071∼7.356, OR:2.807, P = 0.036). SII ≤ 235.85 could identify patients at high risk for surgery, with 87.76% sensitivity, 73.17% specificity, outperformed PLR. Furthermore, mortality was significantly higher in patients with SII ≤ 235.85 than those with SII > 235.85 (20.0% vs. 1.5%, P < 0.001).

CONCLUSION

SII and PLR at NEC diagnosis were independent influencing factors for subsequent surgery. SII ≤ 235.85 may be a useful predictive marker for the identification of surgical NEC and mortality.

Enteric Nervous System in Neonatal Necrotizing Enterocolitis

BACKGROUND

The pathophysiology of necrotizing enterocolitis (NEC) is not clear, but increasing information suggests that the risk and severity of NEC may be influenced by abnormalities in the enteric nervous system (ENS).

OBJECTIVE

The purpose of this review was to scope and examine the research related to ENS-associated abnormalities that have either been identified in NEC or have been noted in other inflammatory bowel disorders (IBDs) with histopathological abnormalities similar to NEC. The aim was to summarize the research findings, identify research gaps in existing literature, and disseminate them to key knowledge end-users to collaborate and address the same in future studies.

METHODS

Articles that met the objectives of the study were identified through an extensive literature search in the databases PubMed, EMBASE, and Scopus.

RESULTS

The sources identified through the literature search revealed that: (1) ENS may be involved in NEC development and post-NEC complications, (2) NEC development is associated with changes in the ENS, and (3) NEC-associated changes could be modulated by the ENS.

CONCLUSION

The findings from this review identify the enteric nervous as a target in the development and progression of NEC. Thus, factors that can protect the ENS can potentially prevent and treat NEC and post-NEC complications. This review serves to summarize the existing literature and highlights a need for further research on the involvement of ENS in NEC.

Current therapy option for necrotizing enterocolitis: Practicalities and challenge

Necrotizing enterocolitis (NEC) is one of the most prevalent neonatal gastrointestinal disorders. Despite ongoing breakthroughs in its treatment and prevention, the incidence and mortality associated with NEC remain high. New therapeutic approaches, such as breast milk composition administration, stem cell therapy, immunotherapy, and fecal microbiota transplantation (FMT) have recently evolved the prevention and the treatment of NEC. This study investigated the most recent advances in NEC therapeutic approaches and discussed their applicability to bring new insight to NEC treatment.

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.

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.

CD16+CD163+ monocytes traffic to sites of inflammation during necrotizing enterocolitis in premature infants

Necrotizing enterocolitis (NEC) is a severe gastrointestinal complication of prematurity. Using suspension and imaging mass cytometry coupled with single-cell RNA sequencing, we demonstrate severe inflammation in patients with NEC. NEC mucosa could be subtyped by an influx of three distinct neutrophil phenotypes (immature, newly emigrated, and aged). Furthermore, CD16⁺CD163⁺ monocytes/Mϕ, correlated with newly emigrated neutrophils, were specifically enriched in NEC mucosa, found adjacent to the blood vessels, and increased in circulation of infants with surgical NEC, suggesting trafficking from the periphery to areas of inflammation. NEC-specific monocytes/Mϕ transcribed inflammatory genes, including TREM1, IL1A, IL1B, and calprotectin, and neutrophil recruitment genes IL8, CXCL1, CXCL2, CXCL5 and had enrichment of gene sets in pathways involved in chemotaxis, migration, phagocytosis, and reactive oxygen species generation. In summary, we identify a novel subtype of inflammatory monocytes/Mϕ associated with NEC that should be further evaluated as a potential biomarker of surgical NEC and a target for the development of NEC-specific therapeutics.

Subclinical necrotizing enterocolitis-induced systemic immune suppression in neonatal preterm pigs

Preterm infants are at high risks of sepsis and necrotizing enterocolitis (NEC). Some develop sepsis shortly after suspected or confirmed NEC, implying that NEC may predispose to sepsis but the underlying mechanisms are unknown. Using NEC-sensitive preterm pigs as models, we investigated the immune status in animals following development of subclinical NEC-like lesions with variable severities. Caesarean-delivered preterm pigs were reared until day 5 or day 9. Blood was analyzed for T-cell subsets, neutrophil phagocytosis, transcriptomics, and immune responses to in vitro LPS challenge. Gut tissues were used for histology and cytokine analyses. Pigs with/without macroscopic NEC lesions were scored as healthy, mild, or severe NEC. Overall NEC incidence was similar on day 5 and day 9 (61%-62%) but with lower severity on day 9, implying gradual mucosal repair following the early phase of NEC. Pigs with NEC showed decreased goblet cell density and increased MPO⁺ and CD3⁺ cell infiltration in the distal small intestine or colon. Mild or severe NEC lesions had limited effects on circulating parameters on day 5. On day 9, pigs with NEC lesions (especially severe lesions) showed systemic immune suppression, as indicated by elevated Treg frequency, impaired neutrophil phagocytosis, low expression of genes related to innate immunity and Th1 polarization, and diminished LPS-induced immune responses. In conclusion, we shows evidence for NEC-induced systemic immune suppression, even with mild and subclinical NEC lesions. The results help to explain that preterm infants suffering from NEC may show high sensitivity to later secondary infections and sepsis.NEW & NOTEWORTHY Necrotizing enterocolitis (NEC) and sepsis are common diseases in preterm infants. Many develop sepsis following an episode of suspected NEC, suggesting NEC as a predisposing factor for sepsis but mechanisms are unclear. Using preterm pigs as a model, now we show that subclinical NEC lesions, independent of clinical confounding factors, induces systemic immune suppression. The results may help to explain the increased risks of infection and sepsis in preterm infants with previous NEC diagnosis.

Exosome-Derived MicroRNAs of Human Milk and Their Effects on Infant Health and Development

Multiple biologically active components of human milk support infant growth, health and development. Milk provides a wide spectrum of mammary epithelial cell-derived extracellular vesicles (MEVs) for the infant. Although the whole spectrum of MEVs appears to be of functional importance for the growing infant, the majority of recent studies report on the MEV subfraction of milk exosomes (MEX) and their miRNA cargo, which are in the focus of this review. MEX and the dominant miRNA-148a play a key role in intestinal maturation, barrier function and suppression of nuclear factor-κB (NF-κB) signaling and may thus be helpful for the prevention and treatment of necrotizing enterocolitis. MEX and their miRNAs reach the systemic circulation and may impact epigenetic programming of various organs including the liver, thymus, brain, pancreatic islets, beige, brown and white adipose tissue as well as bones. Translational evidence indicates that MEX and their miRNAs control the expression of global cellular regulators such as DNA methyltransferase 1-which is important for the up-regulation of developmental genes including insulin, insulin-like growth factor-1, α-synuclein and forkhead box P3-and receptor-interacting protein 140, which is important for the regulation of multiple nuclear receptors. MEX-derived miRNA-148a and miRNA-30b may stimulate the expression of uncoupling protein 1, the key inducer of thermogenesis converting white into beige/brown adipose tissue. MEX have to be considered as signalosomes derived from the maternal lactation genome emitted to promote growth, maturation, immunological and metabolic programming of the offspring. Deeper insights into milk's molecular biology allow the conclusion that infants are both "breast-fed" and "breast-programmed". In this regard, MEX miRNA-deficient artificial formula is not an adequate substitute for breastfeeding, the birthright of all mammals.

Stem cells and exosomes: promising candidates for necrotizing enterocolitis therapy

Necrotizing enterocolitis (NEC) is a devastating disease predominately affecting neonates. Despite therapeutic advances, NEC remains the leading cause of mortality due to gastrointestinal conditions in neonates. Stem cells have been exploited in various diseases, and the application of different types of stem cells in the NEC therapy is explored in the past decade. However, stem cell transplantation possesses several deficiencies, and exosomes are considered potent alternatives. Exosomes, especially those derived from stem cells and breast milk, demonstrate beneficial effects for NEC both in vivo and in vitro and emerge as promising options for clinical practice. In this review, the function and therapeutic effects of stem cells and exosomes for NEC are investigated and summarized, which provide insights for the development and application of novel therapeutic strategies in pediatric diseases. Further elucidation of mechanisms, improvement in preparation, bioengineering, and administration, as well as rigorous clinical trials are warranted.

Necrotizing Enterocolitis

Necrotizing enterocolitis (NEC) is an inflammatory disease affecting premature infants. Intestinal microbial composition may play a key role in determining which infants are predisposed to NEC and when infants are at highest risk of developing NEC. It is unclear how to optimize antibiotic therapy in preterm infants to prevent NEC and how to optimize antibiotic regimens to treat neonates with NEC. This article discusses risk factors for NEC, how dysbiosis in preterm infants plays a role in the pathogenesis of NEC, and how probiotic and antibiotic therapy may be used to prevent and/or treat NEC and its sequelae.

Efficacy of Docosahexaenoic Acid for the Prevention of Necrotizing Enterocolitis in Preterm Infants: A Randomized Clinical Trial

Necrotizing enterocolitis (NEC) is an inflammatory bowel disease and a leading cause of morbidity and mortality in preterm infants. In this study, a randomized double-blind parallel-group (1:1) trial was carried out in two neonatal intensive care units of two tertiary hospitals. Two hundred and twenty-five preterm newborns with an expected functional gastrointestinal tract were recruited and received an enteral dose of 75 mg of docosahexaenoic acid (DHA)/kg body weight or high-oleic sunflower oil daily for 14 days from the first enteral feed after birth. Confirmed NEC was evaluated with Bell’s scale from stage ≥ IIa. Two hundred and fourteen randomized infants were analyzed in terms of the intent-to-treat (DHA-group: n = 105; control-group: n = 109); data for two hundred infants were analysed per protocol. Confirmed NEC was lower in infants from the DHA-group compared with the control-group (0/100 vs. 7/100; p = 0.007), with RR = 0.93 (95% CI 0.881 to 0.981), risk difference = −7%, (95% CI −12.00 to −1.99), and number needed-to-treat = 15 (95% CI 8.3 to 50). Intent-to-treat analysis showed a lower level of treatment failure in the DHA-group compared with the control-group (6/105 (6%) vs. 16/109 (15%); p = 0.03, RR = 0.905, (95% CI 0.826 to 0.991)). The results after multivariate-regression analysis remained significant. Adverse events (apart from the incidence of NEC) were not different between groups. A daily dose of DHA for 14 days starting with the first enteral feed may prevent NEC in preterm infants.

Surfactant protein A reduces TLR4 and inflammatory cytokine mRNA levels in neonatal mouse ileum

Levels of intestinal toll-like receptor 4 (TLR4) impact inflammation in the neonatal gastrointestinal tract. While surfactant protein A (SP-A) is known to regulate TLR4 in the lung, it also reduces intestinal damage, TLR4 and inflammation in an experimental model of necrotizing enterocolitis (NEC) in neonatal rats. We hypothesized that SP-A-deficient (SP-A^-/-) mice have increased ileal TLR4 and inflammatory cytokine levels compared to wild type mice, impacting intestinal physiology. We found that ileal TLR4 and proinflammatory cytokine levels were significantly higher in infant SP-A^-/- mice compared to wild type mice. Gavage of neonatal SP-A^-/- mice with purified SP-A reduced ileal TLR4 protein levels. SP-A reduced expression of TLR4 and proinflammatory cytokines in normal human intestinal epithelial cells (FHs74int), suggesting a direct effect. However, incubation of gastrointestinal cell lines with proteasome inhibitors did not abrogate the effect of SP-A on TLR4 protein levels, suggesting that proteasomal degradation is not involved. In a mouse model of experimental NEC, SP-A^-/- mice were more susceptible to intestinal stress resembling NEC, while gavage with SP-A significantly decreased ileal damage, TLR4 and proinflammatory cytokine mRNA levels. Our data suggests that SP-A has an extrapulmonary role in the intestinal health of neonatal mice by modulating TLR4 and proinflammatory cytokines mRNA expression in intestinal epithelium.

Immunologic Properties of Human Milk and Clinical Implications in the Neonatal Population

Human milk contains various bioactive substances including hormones, immunoglobulins, enzymes, and growth factors in addition to its macro- and micronutrients. It has been suggested that human milk is a vehicle of communication between the maternal and infant immune systems, providing passive protection as well as direct active immunomodulation. Human milk protects newborns against pathogens by acting directly on multiple physiologic systems. Bioactive and immunologic factors regulate the infant's immune, metabolic, and microbiome systems. Breastfeeding protects infants in all socioeconomic groups, showing a pattern of protective dose/duration-response effects. This review summarizes the immune components and immunologic properties of human milk and provides an update of their potential implications in the neonatal population.

Impact and Clinical Implications of Prematurity on Adaptive Immune Development

Purpose of Review

Detail normal adaptive immune maturation during fetal and neonatal life and review the clinical implications of arrested immune development.

Recent Findings

Advancements in the field of immunology have enabled investigations of the adaptive immunity starting during fetal life. New insights have drawn important distinctions between the neonatal and adult immune systems. The presence of diverse immunologic responses in the perinatal period suggests the importance of in utero immune development. Disruption of immune maturation due to premature birth may have significant implications for clinical pathology.

Summary

Establishing protective adaptive immunity during the perinatal period is critical for effective immune responses later in life. Preterm infants are susceptible to aberrant immune system maturation and inflammatory immune responses have been associated with the development of necrotizing enterocolitis (NEC) and bronchopulmonary dysplasia (BPD). Improving our understanding of how immune responses contribute to the pathogenesis of NEC and BPD may offer new opportunities for future treatment and prevention of these diseases.

Human breast milk oligosaccharides attenuate necrotizing enterocolitis in rats by suppressing mast cell accumulation, DPPI activity and TLR4 expression in ileum tissue, and regulating mitochondrial damage of Caco-2 cells

Necrotizing enterocolitis (NEC), a devastating infant disease characterized by severe intestinal necrosis, its pathogenesis is poorly understood, but appears to be multifactorial and highly associated with immaturity of gastrointestinal tract and immature innate-immune system. Breast-milk is effective strategy to protect infants against NEC. This study is using a NEC rat model to investigate the pathological mechanism of NEC involved intestinal-damages, and the therapeutic mechanism of sialylated human milk oligosaccharides (SHMOs) on NEC rats; also using cell model to investigate the effects of SHMOs on colon-epithelial cells (Caco-2) in-vitro. Extraction and characterization of SHMOs from breast milk, establishment of a NEC rat model, histopathological analysis and mast cell accounting of the terminal ileum were taken; The levels of DPPI, TLR4, IL-6, TNF-α, MMP-2/9 and glutathione were measured using various methods. Caco-2 cells were pre-treated with SHMOs and cultured with LPS, histamine, chymase or DPPI, cell viabilities and mitochondrial membrane potential were examined; flow cytometry was used to detect cell cycle. The accumulation of mast cells was found in the ileum of NEC rats, but prohibited by SHMOs treatment; the increased levels of TLR4, DPPI, IL-6, TNF-α, MMP-2/9 in NEC ileum were suppressed by SHMOs in-vivo. SHMOs prevented Caco-2 cells from LPS, histamine, chymase induced damages by surviving cell viability, regulating G0/G1 and S phase in cell cycles, and increasing mitochondrial membrane potential. These findings provide a new insight into the pharmacological mechanism of SHMOs treatment for NEC and suggest that SHMOs needs well attention for therapeutic aims.

Hyaluronan 35 kDa enhances epithelial barrier function and protects against the development of murine necrotizing enterocolitis

BACKGROUND

Disruption of tight junctions (TJs) predisposes to bacterial translocation, intestinal inflammation, and necrotizing enterocolitis (NEC). Previously, studies showed that hyaluronan (HA), a glycosaminoglycan in human milk, maintains intestinal permeability, enhances intestinal immunity, and reduces intestinal infections. In this study, we investigated the effects of HA 35 kDa on a NEC-like murine model.

METHODS

Pups were divided into Sham, NEC, NEC+HA 35, and HA 35. Severity of intestinal injury was compared using a modified macroscopic gut scoring and histologic injury grading. The effect of HA 35 on intestinal permeability was determined by measuring FITC dextran and bacterial translocation. RNA and protein expression of TJ proteins (claudin-2, -3, -4, occludin, and ZO-1) were compared between the groups.

RESULTS

Pups in the NEC+HA 35 group had increased survival and lower intestinal injury compared to untreated NEC. In addition, HA 35 reduced intestinal permeability, bacterial translocation, and proinflammatory cytokine release. Ileal expression of claudin-2, -3, -4, occludin, and ZO-1 was upregulated in NEC+HA 35 and HA 35 compared to untreated NEC and shams.

CONCLUSION

These findings suggest that HA 35 protects against NEC partly by upregulating intestinal TJs and enhancing intestinal barrier function.

Abdominal Distention and Emesis in a Term Neonate

BACKGROUND

Necrotizing enterocolitis (NEC) is a gastrointestinal emergency characterized by ischemic necrosis of the intestinal mucosa, leading to bacterial translocation and pneumatosis of the bowel wall. Although there are numerous studies on clinical presentations of preterm NEC, approximately 10-15% of cases occur in full-term neonates. Nearly 10% of all infants with NEC will develop a rapidly progressive and fatal form of the disease called NEC totalis.

CASE REPORT

A 24-day-old term male infant presented to the Emergency Department (ED) with emesis. The infant was ill-appearing with a tense abdomen and had significant tachycardia and hypotension. The patient was immediately volume resuscitated and started on empiric antibiotics. Initial radiographs revealed no evidence of bowel obstruction or pneumatosis. Pediatric Surgery was consulted, and upper gastrointestinal and abdominal computed tomography scans were obtained, which were nondiagnostic. The patient was taken to the operating room for an exploratory laparotomy after continued clinical deterioration and was diagnosed with NEC totalis and passed away within 6 days. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: This case demonstrates an uncommon presentation of NEC in an otherwise healthy term neonate without any known risk factors. The diagnosis of NEC is challenging because imaging studies may be inconclusive, particularly early in the clinical course. Regardless of the etiology, all infants who present to the ED with signs and symptoms of severe gastrointestinal distress should be treated with basic emergency care, including rapid fluid resuscitation, empiric antibiotics, bowel decompression, and early surgical consultation.

Comparative study of preterm infants fed new and existing human milk fortifiers showed favourable markers of gastrointestinal status

Aim

This study examined the influence of different human milk fortifiers on biomarkers of gastrointestinal immaturity and inflammation in preterm infants.

Methods

We report secondary outcomes from a controlled, double‐blind, randomised, parallel group study conducted from 2011 to 2014 in neonatal intensive care units at 11 metropolitan hospitals in France, Belgium, Germany, Switzerland and Italy. Preterm infants born at up to 32 weeks or weighing up to 1500 g were randomised to a new powdered human milk fortifier (n = 77) or a control fortifier (n = 76) for a minimum of 21 days. We analysed faecal markers of gut inflammation, namely alpha‐1 antitrypsin and calprotectin, and maturity, namely elastase‐1.

Results

Faecal alpha‐1 antitrypsin was slightly lower in the new than control fortifier group after 21 days of full enteral feeding, with a geometric mean and standard deviation of 1.52 ± 1.32 vs 1.82 ± 1.44 mg/g stools (P = .01). There was no significant difference in faecal calprotectin (median [Q1‐Q3] of 296 [136‐565] μg/g stools in both groups combined at study day 21). Faecal elastase‐1 was lower in the new fortifier than control fortifier group (202.5 ± 1.6 vs 257.7 ± 1.5 μg/g stools, P = .016).

Conclusion

Mean values for each parameter were within the ranges in healthy term infants, indicating favourable markers of gastrointestinal status in both groups. In addition, for faecal calprotectin, the relatively high concentration observed in preterm infants fed fortified human milk suggests that the threshold level for detecting necrotising enterocolitis should be revised.

Gut Mucosal and Fecal Microbiota Profiling Combined to Intestinal Immune System in Neonates Affected by Intestinal Ischemic Injuries

Background and Purpose: Early life microbiota plays a crucial role in human health by acting as a barrier from pathogens' invasion and maintaining the intestinal immune homoeostasis. Altered fecal microbiota (FM) ecology was reported in newborns affected by intestinal ischemia. Our purpose was to describe, in these patients, the FM, the mucosal microbiota (MM) and the mucosal immunity.

Methods: Fourteen newborns underwent intestinal resection because of intestinal ischemia. FM and MM were determined through targeted-metagenomics, diversity assignment and Kruskal-Wallis analyses of Operational taxonomic units (OTUs). The mucosal immune cells were analyzed through cytofluorimetry.

Results and Conclusion: Based on the severity intestinal injueris we identified two groups: extensive (EII) and focal intestinal ischemia (FII). FM and MM varied in EII and FII groups, showing in the EII group the predominance of Proteobacteria and Enterobacteriaceae and the reduction of Bacteroidetes and Verrucomicrobia for both microbiota. The MM was characterized by a statistically significant reduction of Bacteroides, Lachnospiraceae and Ruminococcaceae and by a higher diversity in the EII compared to FII group. FM showed a prevalence of Proteobacteria, while the Shannon index was lower in the EII compared to FII group. An overall increment in B- and T-lymphocytes and Natural killer (NK) T-like cells was found for EII mucosal samples associated to an increment of TNF-α and INF-γ expressing cells, compared to FII group. FM and MM carry specific signatures of intestinal ischemic lesions. Further research may be crucial to address the role of specific taxa in EII, expecially with reference to inflammation grade and ischemia extension.

Premature Birth Infants Present Elevated Inflammatory Markers in the Meconium

Introduction: Prematurity, a well-established risk factor for various intestinal diseases in newborns, results in increased morbidity and mortality. However, the intestinal inflammatory status of preterm (PT) infants has been poorly characterized. Here we have broadly described the intestinal and systemic inflammatory status of PT children. Materials and Methods: Meconium and plasma from 39 PT and 32 full term (T) newborns were studied. Fecal calprotectin, polymorphonuclear leukocyte elastase (PMN-E), TNF, IL-17A, IL-8, IP-10, MCP-1, MIP-1, IL-1β, IL-1α, and E-selectin and the enzymatic activities of myeloperoxidase (MPO) and alkaline phosphatase (AP) in meconium were measured. Plasma levels of AP, hepatocyte growth factor, nerve growth factor (NGF), proinflammatory cytokines, leptin, adiponectin, PAI-1, and resistin were also determined. Correlations with gestational age (GA) and birth weight (BW) were studied. Results: Neutrophil derived PMN-E, MPO and calprotectin were increased in the meconium of PT compared to T newborns, while AP was decreased. No significant differences were found in other inflammatory parameters. Considering data from all children, GA and BW showed inverse correlation with neutrophil markers, while AP directly correlated with BW. Plasma levels of IL-1β and NGF were enhanced in PT infants, and were also negatively correlated with BW. PT children additionally showed neutropenia and decreased adiponectin, leptin, haematocrit, and haemoglobin. These parameters (neutrophils, adiponectin, and so forth) were positively correlated with GA and BW, while IL-8, MCP-1, PAI-1, and plasma AP were negatively correlated. PT children showing postnatal morbidity exhibited increased meconium MPO and MIP-1α. Conclusion: PT neonates present a significant elevation of intestinal inflammatory parameters, characterized by the presence of neutrophil markers, associated with mild systemic inflammation.

Mode of delivery and necrotizing enterocolitis in very preterm very-low-birth-weight infants

Objective: To investigate the association between delivery mode and necrotizing enterocolitis (NEC) in very preterm (24-31 weeks' gestational age (GA)) very-low-birth-weight (VLBW) (≤1500 g) infants.Design: Population-based observational study using univariate and multivariable logistic regression analyses.Setting: The Israel National VLBW infant database 1995-2015.Patients: 20,223 VLBW infants, 11,832 singletons and 8391 multiples.Main outcome measures: The association of NEC occurrence to delivery by cesarean section (CS) in singletons and multiples VLBW very preterm infants.Results: NEC occurred in 7.6% of singletons and 6.4% of multiples. 71.5% were delivered by CS (64.7% of singletons, 80.9% of multiples). CS delivery was not significantly associated with NEC stages 2-3 in singletons; but multiple births CS were associated with significantly higher odds for NEC (OR 1.31, 95% CI 1.01-1.69). Odds for NEC were greater with lower GA, small for GA (SGA) and patent ductus arteriosus (PDA) in both singletons and multiples, and lower in multiples with antenatal corticosteroids.Conclusions: We demonstrated association between deliveries by CS and increased risk for NEC only in multiple pregnancies.

Abdominal ultrasound should become part of standard care for early diagnosis and management of necrotising enterocolitis: a narrative review

Necrotising enterocolitis (NEC) is a leading cause of death and disability in preterm newborns. Early diagnosis through non-invasive investigations is a crucial strategy that can significantly improve outcomes. Hence, this review gives particular attention to the emerging role of abdominal ultrasound (AUS) in the early diagnosis of NEC, its performance against abdominal radiograph and the benefits of AUS use in daily practice. AUS has been used in the diagnosis and management of NEC for a couple of decades. However, its first-line use has been minimal, despite growing evidence demonstrating AUS can be a critical tool in the early diagnosis and management of NEC. In 2018, the NEC group of the International Neonatal Consortium recommended using AUS to detect pneumatosis and/or portal air in preterm NEC as part of the 'Two out of three' model. To facilitate widespread adoption, and future improvement in practice and outcomes, collaboration between neonatologists, surgeons and radiologists is needed to generate standard operating procedures and indications for use for AUS. The pace and scale of the benefit generated by use of AUS can be amplified through use of computer-aided detection and artificial intelligence.

Recent Potential Noninvasive Biomarkers in Necrotizing Enterocolitis

Necrotizing enterocolitis (NEC) is a rare but devastating gastrointestinal disease that predominately affects preterm neonates. Numerous studies have revealed that NEC is strongly associated with very low birth weight, degree of prematurity, formula feeding, infection, hypoxic/ischemic injury, and enteric dysbiosis. Given these clinical associations, the search for a deeper understanding of disease pathogenesis has led to an intense interest in the discovery and development of noninvasive biomarkers of NEC from stool, urine, and serum. Biomarkers for NEC may serve at least two general purposes of urgent unmet need: to improve diagnostic accuracy and disease prediction and to reveal the mechanism of the disease. This review will provide an overview of recent research focused on clinical NEC and highlight the advances that were made within the past five years towards the development of noninvasive diagnostic biomarkers.

Challenges in Advancing Necrotizing Enterocolitis Research

Progressing necrotizing enterocolitis research is difficult because the disease is variable in presentation, there are difficulties in making a precise diagnosis, a reliable agreed case-definition is currently lacking, and there is a paucity of preclinical research to identify etiologic targets. The major challenges of the cost of clinical trials and need for long-term outcome ascertainment could be eased through incorporation of novel randomization approaches and data collection into routine care, and collaboration between public-sector and industry funders.

Necrotizing enterocolitis

Necrotizing enterocolitis (NEC) is an acute inflammatory disease of the intestine which primarily affects preterm infants and is a leading cause of morbidity and mortality in the neonatal intensive care unit. From a clinical standpoint, and during the early course of the disease, NEC can be difficult to distinguish from other diseases and conditions common to the preterm infant, and this warrants the need for specific disease biomarkers. The pathogenesis of NEC is only partly understood but likely involves an altered intestinal barrier immune response to feeding and the developing microbiome. Recent evidence points toward a role of the enteric nervous system in NEC pathogenesis. In this issue, Meister and colleagues use a rodent model of NEC to demonstrate that NEC is associated with diminished vagal tone, as determined by decreased high-frequency heart rate variability (HF-HRV), and altered myenteric nitrergic inhibitory neurotransmission. These results augment their previous findings that describe decreased HF-HRV in human preterm infants with NEC. This mini-review provides a brief summary of clinical and pathophysiologic aspects of NEC with focus on certain aspects of neurogastroenterology.

Development of a human milk concentrate with human milk lyophilizate for feeding very low birth weight preterm infants: A preclinical experimental study

Breast milk is considered the gold standard nutritional resource for very low birth weight (VLBW) infants in terms of nutrients and protective factors. If mother's milk is not available, the second choice is donated and fortified human milk (HM) from the Human Milk Bank (HMB). This study hypothesized that HM could be lyophilized and used as an additive to increase the levels of macronutrients and micronutrients available to VLBW infants. This study aimed to constitute a lyophilized HM concentrate and determine the osmolality and the concentration of macronutrients and micronutrients in HM samples at “baseline” and in “HM concentrates”, analyzed immediately (HMCI), and after 3 (HMC3m) and 6 (HMC6m) months of freezing. Osmolality was verified using the freezing point osmometric method. Macronutrient quantification was performed using the MIRIS Human Milk Analyzer. Micronutrients were determined by Flame Atomic Absorption Spectrophotometry and by the automated colorimetric method. Bayesian linear mixed effect models were adjusted using OpenBUGS to estimate mean differences and 95% credibility intervals (CrI) of osmolality and of macro- and micronutrients between the types of HM samples. A comparison of dosage values showed a significant increase between HM baseline and HMCI, HMC3m, and HMC6m. Comparing HM baseline and HMCI highlighted the increase in energy content and the concentration of carbohydrates and total lipids. The Ca and P contents increased and the levels of energy, total lipids, and Cu were reduced in HMC3m compared to HMCI. Ca, Mg, K, Zn, and P increased and the levels of energy, total lipids, and Cu were reduced in HMC6m, compared to HMCI. The present study confirms the possibility of formulation and utilization of the immediate concentrate. Partial stability of HM concentrates generated from freeze-drying of donated milk do not recommend storage.