Cytokines associated with necrotizing enterocolitis in extremely-low-birth-weight infants

Estrogen Alleviates Oxidative Bowel Injury and Neuroinflammation in Necrotizing Enterocolitis

INTRODUCTION

High mortality and morbidity of neonates with necrotizing enterocolitis (NEC) necessitates the investigation of novel therapies to improve outcomes. It was aimed to elucidate the potential therapeutic effect of estrogen receptor agonists on NEC-induced intestinal and brain injury in rats.

METHODS

Sprague-Dawley pups of both sexes were separated from their mothers at postnatal 5th d. Feeding with formula along with a single session of hypoxia was applied to induce NEC, while control pups were kept with their mothers. The NEC rats received either vehicle, estrogen receptor α (ERα) agonist propyl pyrazole triol (1 mg/kg/day), ERβ agonist diarylpropionitrile (1 mg/kg/day), or 17β-estradiol (1 mg/kg/day) during maternal separation. All pups were decapitated on postnatal 9th d to collect intestinal and brain tissue samples.

RESULTS

Elevation in proinflammatory cytokines, apoptosis, and microscopically and biochemically evident oxidative injury in both the intestinal and brain tissues were observed in NEC-induced pups. In both the intestinal and brain tissues, nerve growth factor and brain-derived neurotrophic factor protein levels were depleted, expressions of both the ESR1 and ESR2 genes were downregulated, while treatment with 17β-estradiol or ER agonists alleviated extent of oxidative injury of the intestines and brain tissue, upregulated nerve growth factor, brain-derived neurotrophic factor, and ER gene expressions, abolished NEC-induced decrease in claudin-3 expression, increased the survival rates, improved the clinical states of the survived pups at varying degrees.

CONCLUSIONS

Activation of estrogen signaling by receptor agonists alleviated NEC-induced intestinal and cerebral injury, implicating that estrogen agonists could be regarded as promising preventive/therapeutic agents for NEC.

Tailored Combinations of Human Milk Oligosaccharides Modulate the Immune Response in an In Vitro Model of Intestinal Inflammation

Infants rely on their developing immune system and the protective components of breast milk to defend against bacterial and viral pathogens, as well as immune disorders such as food allergies, prior to the introduction of solid foods. When breastfeeding is not feasible, fortified infant formula will most frequently be offered, usually based on a cow's milk-based substitute. The current study aimed to explore the immunomodulatory effects of combinations of commercially available human milk oligosaccharides (HMOs). An in vitro co-culture model of Caco-2 intestinal epithelial cells and THP-1 macrophages was established to replicate the hallmarks of intestinal inflammation and to evaluate the direct effects of different synthetic HMO combinations. Notably, a blend of the most prevalent fucosylated and sialylated HMOs, 2'-fucosyllactose (2'-FL) and 6'-siallylactose (6'-SL), respectively, resulted in decreased pro-inflammatory cytokine levels. These effects were dependent on the HMO concentration and on the HMO ratio resembling those in breastmilk. Interestingly, adding additional HMO structures did not enhance the anti-inflammatory effects. This research highlights the importance of carefully selecting HMO combinations in nutritional products, particularly for infant milk formulations, to effectively mimic the benefits associated with breastmilk.

Clinical and Growth Correlates of Retinopathy of Prematurity in Preterm Infants with Surgical Necrotizing Enterocolitis and Intestinal Perforation

OBJECTIVE

 This study aimed to identify the clinical and growth parameters associated with retinopathy of prematurity (ROP) in infants with necrotizing enterocolitis (NEC) and spontaneous ileal perforation (SIP).

STUDY DESIGN

 We conducted a retrospective cohort study that compared clinical data before and after NEC/SIP onset in neonates, categorizing by any ROP and severe ROP (type 1/2) status.

RESULTS

 The analysis included 109 infants with surgical NEC/SIP. Sixty infants (60/109, 55%) were diagnosed with any ROP, 32/109 (29.3%) infants (22% type 1 and 7.3% type 2) with severe ROP. On univariate analysis, those with severe ROP (32/109, 39.5%) were of lower median gestational age (GA, 23.8 weeks [23.4, 24.6] vs. 27.3 [26.3, 29.0], p < 0.001), lower median birth weight (625 g [512, 710] vs. 935 [700, 1,180], p < 0.001) and experienced higher exposure to clinical chorioamnionitis (22.6 vs. 2.13%, p < 0.006), and later median onset of ROP diagnosis (63.0 days [47.0, 77.2] vs. 29.0 [19.0, 41.0], p < 0.001), received Penrose drain placement more commonly (19 [59.4%] vs. 16 [34.0%], p = 0.04), retained less residual small bowel (70.0 cm [63.1, 90.8] vs. 90.8 [72.0, 101], p = 0.007) following surgery, were exposed to higher FiO2 7 days after birth (p = 0.001), received ventilation longer and exposed to higher FiO2 at 2 weeks (p < 0.05) following NEC and developed acute kidney injury (AKI) more often (25 [86.2%] vs. 20 [46.5%], p = 0.002) than those without ROP. Those with severe ROP had lower length, weight for length, and head circumference z scores. In an adjusted Firth's logistic regression, GA (adjusted odds ratio [aOR] = 0.51, 95% confidence interval [CI]: [0.35, 0.76]) and diagnosis at later age (aOR = 1.08, 95% CI: [1.03, 1.13]) was shown to be significantly associated with any ROP.

CONCLUSION

 Infants who develop severe ROP following surgical NEC/SIP are likely to be younger, smaller, have been exposed to more O2, develop AKI, and grow poorly compared with those did not develop severe ROP.

KEY POINTS

· Thirty percent of infants with NEC/SIP had severe ROP.. · Those with severe ROP had poor growth parameters before and after NEC/SIP.. · Risk factors based ROP prevention strategies are needed to have improved ophthalmic outcomes..

Necrotizing Enterocolitis and Neurodevelopmental Impairments: Microbiome, Gut, and Brain Entanglements

There is significant communication and interdependence among the gut, the microbiome, and the brain during development. Diseases, such as necrotizing enterocolitis (NEC), highlight how injury to the immature gastrointestinal tract leads to long-term neurological consequences, due to vulnerabilities of the brain in the early stages of life. A better understanding of the developing gut-microbiota-brain axis is needed to both prevent and treat the devastating consequences of these disease processes. The gut-microbiota-brain axis is a bidirectional communication pathway that includes metabolic, nervous, endocrine, and immune components. In this review, we discuss gut development, microbiome colonization and maturation, and the interactions that influence neurodevelopment in the context of NEC. We describe the components of the gut-brain axis and how the microbiome is an integral member of this relationship. Finally, we explore how derangements within the microbiome and gut-microbiota-brain axis affect the normal development and function of the other systems and long-term neurodevelopmental consequences for patients.

Clinical Correlates of Moderate-to-Severe Bronchopulmonary Dysplasia in Preterm Infants following Surgical Necrotizing Enterocolitis

OBJECTIVE

The aim of the study is to determine clinical correlates of moderate to severe bronchopulmonary dysplasia (BPD) in preterm infants following surgical necrotizing enterocolitis (NEC).

STUDY DESIGN

This is a retrospective, single-center cohort study comparing patients with moderate to severe BPD to patients with non/mild BPD among surgical NEC infants. BPD was defined by NIH 2001 consensus definition.

RESULTS

Of 92 consecutive neonates with surgical NEC, 77% (71/92) had moderate/severe BPD and 22% (21/92) had non/mild BPD. The patent ductus arteriosus (PDA) was significantly higher in those developing moderate/severe BPD (67.6% [48/71]) than non/mild BPD (28.6% [6/21]; p = 0.001). Postoperatively, infants with moderate/severe BPD had more severe acute kidney injury (AKI; 67.6 [48/71] vs. 28.6% [6/21]; p = 0.001), were intubated longer (40.5 [interquartile (IQR): 12, 59] vs. 6 days [IQR: 2, 13]; p <0.001), received more parenteral nutrition (109 [IQR: 77, 147] vs. 55 days [IQR: 19, 70]; p <0.001), developed higher surgical morbidity (46.5 [33/71] vs. 14.3% [3/21]; p = 0.008), had more intestinal failure (62.5 vs. 13.3%; p <0.001), required a longer hospital stay (161 [IQR: 112, 186] vs. 64 days [IQR: 20, 91]; p <0.001), and were more likely to need home oxygen. In a multivariable analysis, lower birth weight (OR = 0.3, [95% confidence interval (CI): 0.1-0.5]; p = 0.001), PDA (OR = 10.3, [95% CI: 1.6-65.4]; p = 0.014), and longer parenteral nutritional days (OR = 8.8; [95% CI: 2.0-43.0]; p = 0.005) were significantly and independently associated with higher odds of moderate/severe versus non-/mild BPD.

CONCLUSION

Development of moderate/severe BPD occurred in the majority of preterm infants with surgical NEC in this consecutive series. Preterm infants with moderate/severe BPD were more likely to have a PDA before NEC. Development of moderate/severe BPD was associated with significantly greater burden and duration of postoperative morbidity following surgical NEC. Identifying surgical NEC infants at increased risk of moderate/severe BPD and developing lung protection strategies may improve surgical NEC outcomes.

KEY POINTS

· Three-fourths of preterm infants experienced severe lung injury following surgical NEC.. · The infants with severe moderate/severe BPD were most likely associated with greater duration of postoperative morbidity.. · There is need to understand and develop lung protective strategies in infants with surgical NEC..

Prevention of Inflammatory Disorders in the Preterm Neonate: An Update with a Special Focus on Bronchopulmonary Dysplasia

BACKGROUND

The rates of major neonatal morbidities, such as bronchopulmonary dysplasia, necrotizing enterocolitis, preterm white matter disease, and retinopathy of prematurity, remain high among surviving preterm infants. Exposure to inflammatory stimuli and the subsequent host innate immune response contribute to the risk of developing these complications of prematurity. Notably, the burden of inflammation and associated neonatal morbidity is inversely related to gestational age - leaving primarily but not exclusively the tiniest babies at highest risk.

SUMMARY

Avoidance, prevention, and treatment of inflammation to reduce this burden remain a major goal for neonatologists worldwide. In this review, we discuss the link between the host response to inflammatory stimuli and the disease state. We argue that inflammatory exposures play a key role in the pathobiology of preterm birth and that preterm neonates hereafter are highly susceptible to immune stimulation not only from their surrounding environment but also from therapeutic interventions employed in clinical care. Using bronchopulmonary dysplasia as an example, we report clinical studies demonstrating the potential utility of targeting inflammation to prevent this neonatal morbidity. On the contrary, we highlight limitations in our current understanding of how inflammation contributes to disease prevention and treatment.

KEY MESSAGE

To be successful in preventing and treating inflammation-driven morbidity in neonatal intensive care, it may be necessary to better identify at-risk patients and pair therapeutic interventions to key pathways and mediators of inflammation-associated neonatal morbidity identified in pre-clinical and translational studies.

Epigenetic Insights Into Necrotizing Enterocolitis: Unraveling Methylation-Regulated Biomarkers

Necrotizing enterocolitis (NEC) is a multifactorial gastrointestinal disease with high morbidity and mortality among premature infants. This study aimed to identify novel methylation-regulated biomarkers in NEC intestinal tissue through multiomics analysis. We analyzed DNA methylation and transcriptome datasets from ileum and colon tissues of patients with NEC. We identify methylation-related differential genes (MrDEGs) based on the rule that the degree of methylation in the promoter region is inversely proportional to RNA transcription. These MrDEGs included ADAP1, GUCA2A, BCL2L14, FUT3, MISP, USH1C, ITGA3, UNC93A and IL22RA1. Single-cell data revealed that MrDEGs were mainly located in the intestinal epithelial part of intestinal tissue. These MrDEGs were verified through Target gene bisulfite sequencing and RT-qPCR. We successfully identified and verified the ADAP1, GUCA2A, IL22RA1 and MISP, primarily expressed in intestinal epithelial villus cells through single-cell data. Through single-gene gene set enrichment analysis, we found that these genes participate mainly in the pathological process of T-cell differentiation and the suppression of intestinal inflammation in NEC. This study enhances our understanding of the pathogenesis of NEC and may promote the development of new precision medicine methods for NEC prediction and diagnosis.

A graded neonatal mouse model of necrotizing enterocolitis demonstrates that mild enterocolitis is sufficient to activate microglia and increase cerebral cytokine expression

Background

Necrotizing enterocolitis (NEC) is an inflammatory gastrointestinal process that afflicts approximately 10% of preterm infants born in the United States each year, with a mortality rate of 30%. NEC severity is graded using Bell's classification system, from stage I mild NEC to stage III severe NEC. Over half of NEC survivors present with neurodevelopmental impairment during adolescence, a long-term complication that is poorly understood but can occur even after mild NEC. Although multiple animal models exist, none allow the experimenter to control nor represent the gradient of symptom severities seen in NEC patients. We bridge this knowledge gap by developing a graded murine model of NEC and studying its relationship with neuroinflammation across a range of NEC severities.

Methods

Postnatal day 3 (P3) C57BL/6 mice were fed a formula containing different concentrations (0% control, 0.25%, 1%, 2%, and 3%) of dextran sodium sulfate (DSS). P3 mice were fed every 3 hours for 72-hours. We collected data on weight gain and behavior (activity, response, body color) during feeding. At the end of the experiment, we collected tissues (intestine, liver, plasma, brain) for immunohistochemistry, immunofluorescence, and cytokine and chemokine analysis.

Results

Throughout NEC induction, mice fed higher concentrations of DSS died sooner, lost weight faster, and became sick or lethargic earlier. Intestinal characteristics (dilation, color, friability) were worse in mice fed with higher DSS concentrations. Histology revealed small intestinal disarray among mice fed all DSS concentrations, while higher DSS concentrations resulted in reduced small intestinal cellular proliferation and increased hepatic and systemic inflammation. In the brain, IL-2, G-CSF, and CXCL1 concentrations increased with higher DSS concentrations. Although the number of neurons and microglia in the CA1 hippocampal region did not differ, microglial branching was significantly reduced in DSS-fed mice.

Conclusion

We characterize a novel graded model of NEC that recapitulates the full range of NEC severities. We show that mild NEC is sufficient to initiate neuroinflammation and microglia activation. This model will facilitate studies on the neurodevelopmental effects of NEC.

Extracellular Nicotinamide Phosphoribosyltransferase Is a Therapeutic Target in Experimental Necrotizing Enterocolitis

Necrotizing enterocolitis (NEC) is the most common gastrointestinal emergency of prematurity. Postulated mechanisms leading to inflammatory necrosis of the ileum and colon include activation of the pathogen recognition receptor Toll-like receptor 4 (TLR4) and decreased levels of transforming growth factor beta (TGFβ). Extracellular nicotinamide phosphoribosyltransferase (eNAMPT), a novel damage-associated molecular pattern (DAMP), is a TLR4 ligand and plays a role in a number of inflammatory disease processes. To test the hypothesis that eNAMPT is involved in NEC, an eNAMPT-neutralizing monoclonal antibody, ALT-100, was used in a well-established animal model of NEC. Preterm Sprague-Dawley pups delivered prematurely from timed-pregnant dams were exposed to hypoxia/hypothermia and randomized to control-foster mother dam-fed rats, injected IP with saline (vehicle) 48 h after delivery; control + mAB-foster dam-fed rats, injected IP with 10 µg of ALT-100 at 48 h post-delivery; NEC-orally gavaged, formula-fed rats injected with saline; and NEC + mAb-formula-fed rats, injected IP with 10 µg of ALT-100 at 48 h. The distal ileum was processed 96 h after C-section delivery for histological, biochemical, molecular, and RNA sequencing studies. Saline-treated NEC pups exhibited markedly increased fecal blood and histologic ileal damage compared to controls (q < 0.0001), and findings significantly reduced in ALT-100 mAb-treated NEC pups (q < 0.01). Real-time PCR in ileal tissues revealed increased NAMPT in NEC pups compared to pups that received the ALT-100 mAb (p < 0.01). Elevated serum levels of tumor necrosis factor alpha (TNFα), interleukin 6 (IL-6), interleukin-8 (IL-8), and NAMPT were observed in NEC pups compared to NEC + mAb pups (p < 0.01). Finally, RNA-Seq confirmed dysregulated TGFβ and TLR4 signaling pathways in NEC pups that were attenuated by ALT-100 mAb treatment. These data strongly support the involvement of eNAMPT in NEC pathobiology and eNAMPT neutralization as a strategy to address the unmet need for NEC therapeutics.

The Difference of Milk-Derived Extracellular Vesicles from Cow Colostrum and Mature Milk on miRNAs Expression and Protecting Intestinal Epithelial Cells against Lipopolysaccharide Damage

Intestinal epithelial cells (IECs) play crucial roles in forming an essential barrier, providing host defense against pathogens and regulating nutrients absorption. Milk-derived extracellular vesicles (EVs) within its miRNAs are capable of modulating the recipient cell function. However, the differences between colostrum and mature milk EVs and their biological function in attenuating intestinal epithelial cell injury remain poorly understood. Thus, we carried out the present study to characterize the difference between colostrum and mature milk-derived miRNA of EVs and the effect of colostrum and mature milk EVs on the proliferation, apoptosis, proinflammatory cytokines and intestinal epithelial barrier related genes in IEC-6 induced by LPS. Differential expression of 329 miRNAs was identified between colostrum and mature milk EVs, with 185 miRNAs being downregulated and 144 upregulated. In addition, colostrum contains a greater number and protein concentration of EVs than mature milk. Furthermore, compared to control, EVs derived from colostrum significantly inhibited the expression of apoptosis- (Bax, p53, and caspase-3) and proinflammatory-related genes (TNFα, IL6, and IL1β). EVs derived from mature milk did not affect expression of apoptosis-related genes (Bax, p53, bcl2, and caspase-3). The EVs derived from mature milk significantly inhibited the expression of proinflammatory-related genes (TNFα and IL6). Western blot analysis also indicated that colostrum and mature milk EVs significantly decreased the apoptosis of IEC-6 cells. The EdU assay results showed that colostrum and mature milk EVs significantly increased the proliferation of IEC-6 cells. The expression of intestinal barrier-related genes (TJP1, CLDN1, OCLN, CDX2, MUC2, and IGF1R) was significantly promoted in IEC-6 cells after colostrum and mature milk EVs addition. Importantly, colostrum and mature milk EVs significantly relieved the LPS-induced inhibition of proliferation and intestinal barrier-related genes expression and attenuated apoptosis and proinflammatory responses induced by LPS in IEC-6 cells. Flow cytometry and Western blot analysis also indicated that colostrum and mature milk EVs significantly affect the apoptosis of IEC-6 cells induced by LPS. The results also indicated that EVs derived from colostrum had better effects on inhibiting the apoptosis- and proinflammatory cytokines-related genes expression. However, the EVs derived from mature milk exhibited beneficial effects on intestinal epithelial barrier protection. The present study will provide a better understanding of the role of EVs derived from colostrum and milk in dairy cows with different responses in the regulation of intestinal cells function, and also presents new evidence for the change of EVs cargos during various stages of lactation.

Clinical correlates of cerebellar injury in preterm infants with surgical necrotizing enterocolitis

BACKGROUND

The preterm infants are at risk of cerebellar injury and the risk factors for necrotizing enterocolitis (NEC) associated cerebellar injury are not fully understood.

AIM

Determine the risk factors of cerebellar injury in infants with surgical necrotizing enterocolitis (NEC).

METHODS

Retrospective study compared clinical/pathological information between surgical NEC infants with and those without cerebellar injury detected on brain MRI obtained at term equivalent age. Cerebellar Injury patterns that we identified on MRI brain were cerebellar hemorrhage, siderosis and/or cerebellar volume loss.

RESULTS

Cerebellar injury (21/65, 32.3%) in preterm infants with NEC was associated with patent ductus arteriosus (PDA) (18/21(85.7%) vs. 25/44(56.8%); p = 0.021), blood culture positive sepsis (13/21 (61.9%) vs. 11/44 (25%); p = 0.004) following NEC, predominantly grew gram positive bacteria (9/21(42.9%) vs. 4/44(9.1%); p = 0.001), greater red cell transfusion, higher rates of cholestasis following NEC and differences in intestinal histopathology (more hemorrhagic and reparative lesions) on univariate analysis. Those with cerebellar injury had higher grade white matter injury (14/21 (66.7%) vs. 4/44(9.1%) p = 0.0005) and higher-grade ROP (70.6% vs. 38.5%; p = 0.027) than those without cerebellar injury.On multilogistic regression, the positive blood culture sepsis (OR 3.9, CI 1.1-13.7, p = 0.03), PDA (OR 4.5, CI 1.0-19.9, p = 0.04) and severe intestinal pathological hemorrhage (grade 3-4) (OR 16.9, CI 2.1-135.5, p = 0.007) were independently associated with higher risk of cerebellar injury.

CONCLUSION

Preterm infants with surgical NEC with positive blood culture sepsis, PDA, and severe intestinal hemorrhagic lesions (grade 3-4) appear at greater risk for cerebellar injury.

Clinical Correlates of Cerebellar Injury in Preterm Infants with Surgical Necrotizing Enterocolitis

Objective

Determine the risk factors of cerebellar injury in infants with surgical necrotizing enterocolitis (NEC).

Methods

Retrospective study compared clinical/pathological information between surgical NEC infants with and those without cerebellar injury.

Results

Infants with cerebellar injury (21/65, 32.3%) had significantly more hemorrhagic and the reparative lesions on the intestinal histopathology, had patent ductus arteriosus (PDA) more often, received red cell transfusion frequently, had blood culture positive sepsis and grew gram positive organisms more often and had cholestasis frequently following NEC than those without cerebellar injury. On multilogistic regression, the positive blood culture sepsis (OR 3.9, CI 1.1-13.7, p = 0.03), PDA (OR 4.5, CI 1.0-19.9, p = 0.04) and severe hemorrhage (grade 3-4)(OR 16.9, CI 2.1-135.5, p = 0.007) were independently associated with higher risk of cerebellar injury.

Conclusion

The cerebellar injury was most likely associated with positive blood culture sepsis following NEC, PDA, and severe hemorrhage lesions (grade 3-4) in infants with surgical NEC.

Novel scoring system for early diagnosis of necrotizing enterocolitis: integrating clinical and laboratory data with urinary caveolin-1 levels

Introduction

Necrotizing enterocolitis (NEC) poses a significant threat to preterm infants, with nonspecific early manifestations complicating timely diagnosis. Therefore, this study aimed to develop a novel scoring system for early diagnosis of NEC, incorporating clinical and laboratory data with urinary caveolin-1 levels.

Material and methods

A single-center prospective cohort study was conducted at a tertiary hospital in East Java, Indonesia. NEC diagnosis was established by Bell's criteria and proven gut dysbiosis. Urinary levels of claudin-2, caveolin-1, and epidermal growth factor (EGF) were assessed as potential indicators of tight junction disruption. The selected urine biomarker cutoff value was determined using symbolic classification analysis and combined with clinical and laboratory parameters from Bell's criteria to create an NEC scoring system, validated with the Aiken index. Sensitivity and specificity analyses were performed.

Results

Thirty-four neonates, comprising NEC, preterm non-NEC, and term infants, were included. qPCR analysis highlighted elevated Klebsiella, Lactobacillus, Clostridium, and Bacteroides levels in NEC patients, indicating a gut dysbiosis trend. Among 3 biomarkers, caveolin-1 ≥ 17.81 ng/dl on day 3 demonstrated 72.86% negative predictive value and 87.50% positive predictive value. The combined scoring system which comprised abdominal cellulitis, distension, radiology, advanced resuscitation at birth, prematurity or low birthweight, platelet count, sepsis, orogastric retention, metabolic acidosis and caveolin-1 findings exhibited an AUC of 0.922 (95% CI: 0.81-1.00, p < 0.001), with ≥ 1.81 as the cutoff, offering 93% sensitivity and 94% specificity.

Conclusions

Urine caveolin-1 on day 3 signifies enterocyte tight junction damage and the acute phase of NEC in premature infants. The proposed scoring system demonstrates good performance in predicting NEC incidence in preterm infants.

Evaluation of white matter microstructural alterations in premature infants with necrotizing enterocolitis

Background

Preterm infants with necrotizing enterocolitis (NEC) are at high risk of adverse neurodevelopmental outcomes. The aim of this study was to explore the value of diffusion tensor imaging (DTI) combined with serum C-reactive protein (CRP) and procalcitonin (PCT) in evaluating alterations of white matter (WM) microstructure in preterm infants with NEC.

Methods

A retrospective cross-sectional study was conducted in which all participants were consecutively enrolled at The Third Affiliated Hospital of Zhengzhou University from June 2017 and October 2021. Data from 30 preterm infants with NEC [mean gestational age at birth 31.41±1.15 weeks; mean age at magnetic resonance imaging (MRI) 37.53±3.08 weeks] and 40 healthy preterm infants with no NEC were recorded (mean gestational age at birth 32.27±2.09 weeks; mean age at MRI 37.15±3.23 weeks). WM was used to obtain the fractional anisotropy (FA) and mean diffusivity (MD) values of the regions of interest (ROIs). Additionally, serum levels of CRP and PCT were determined. Spearman correlation analysis was performed between the WM-derived parameters, CRP level, and the PCT serum index.

Results

Preterm infants with NEC had reduced FA values and elevated MD values in WM regions [posterior limbs of the internal capsule (PLIC), lentiform nucleus (LN), frontal white matter (FWM)] compared to the control group (P<0.05). Additionally, the FA of the PLIC was negatively correlated with serum CRP (r=-0.846; P<0.05) and PCT (r=-0.843; P<0.05). Meanwhile, the MD of PLIC was positively correlated with serum CRP (r=0.743; P<0.05) and PCT (r=0.743; P<0.05, respectively). The area under the curve (AUC) of FA and MD combined with CRP and PCT in the diagnosis of WM microstructure alterations with NEC was 0.968, representing a considerable improvement in predicted efficacy over single indicators, including FA [AUC: 0.938; 95% confidence interval (CI): 0.840-0.950], MD (AUC: 0.807; 95% CI: 0.722-0.838), CRP (AUC: 0.867; 95% CI: 0.822-0.889), and PCT (AUC: 0.706; 95% CI: 0.701-0.758).

Conclusions

WM can noninvasively and quantitatively assess the WM microstructure alterations in preterm infants with NEC. WM combined with serum CRP and PCT demonstrated superior performance in detecting and evaluating WM microstructure alterations in preterm infants with NEC.

New insights into intestinal macrophages in necrotizing enterocolitis: the multi-functional role and promising therapeutic application

Necrotizing enterocolitis (NEC) is an inflammatory intestinal disease that profoundly affects preterm infants. Currently, the pathogenesis of NEC remains controversial, resulting in limited treatment strategies. The preterm infants are thought to be susceptible to gut inflammatory disorders because of their immature immune system. In early life, intestinal macrophages (IMφs), crucial components of innate immunity, demonstrate functional plasticity and diversity in intestinal development, resistance to pathogens, maintenance of the intestinal barrier, and regulation of gut microbiota. When the stimulations of environmental, dietary, and bacterial factors interrupt the homeostatic processes of IMφs, they will lead to intestinal disease, such as NEC. This review focuses on the IMφs related pathogenesis in NEC, discusses the multi-functional roles and relevant molecular mechanisms of IMφs in preterm infants, and explores promising therapeutic application for NEC.

Oropharyngeal application of colostrum or mother's own milk in preterm infants: a systematic review and meta-analysis

CONTEXT

Many preterm neonates often cannot be fed enterally and hence do not receive the benefits of colostrum. Oropharyngeal application of colostrum is a novel way of harnessing the immunological benefits of colostrum. Randomized controlled trials (RCTs) investigating the efficacy of this approach have shown variable results.

OBJECTIVE

The aim of this systematic review was to synthesize available data on the effect of oropharyngeal application of colostrum or mother's own milk (CMOM) in preterm infants.

DATA SOURCES

Six electronic databases (MEDLINE, Embase, CINAHL, Scopus, Web of Science, and Cochrane Library) were searched until January 13, 2022. Only RCTs comparing oral application of CMOM with placebo/routine care in preterm infants were eligible. Studies enrolling term neonates or administering enteral feeds were excluded.

DATA EXTRACTION

Two investigators independently extracted data using a structured proforma.

DATA ANALYSIS

The Cochrane Risk of Bias 2 tool was used to assess bias. Random-effects meta-analysis was undertaken using RevMan 5.4 software. From 2787 records identified, 17 RCTs enrolling 4106 preterm infants were included. There was no significant difference between groups in incidence of necrotizing enterocolitis (NEC) stage 2 or higher (RR = 0.65; 95%CI, 0.36-1.20; 1089 participants in 12 trials). Application of CMOM significantly reduced the incidence of sepsis (RR = 0.72; 95%CI, 0.56-0.92; 1511 participants in 15 studies) and any stage of NEC (RR = 0.58; 95%CI, 0.37-0.92; 1616 participants in 16 trials). The CMOM group achieved full enteral feeds 1.75 days sooner (95%CI, 0.3-3.2 days; 1580 participants in 14 studies) and had higher weight at discharge (MD = 43.9 g; 95%CI, 3-85 g; 569 participants in 3 studies). There were no statistically significant differences in other outcomes.

CONCLUSIONS

Evidence with low to very low certainty suggests CMOM has a beneficial effect on NEC (any stage), sepsis, and time to full enteral feeds. Given its low cost and minimal risk of harm, routine CMOM use may be considered in preterm neonates.

PROSPERO REGISTRATION NUMBER

CRD42021262763.

Human breast milk: A promising treatment for necrotizing enterocolitis

Necrotizing enterocolitis (NEC) is a severe gastrointestinal disorder occurring in newborns, with a mortality rate ranging from 20 % to 30 %. The existing therapeutic approaches for NEC are limited in their effectiveness. Various factors contribute to the development of NEC, including disruption of barrier function, dysregulation of the intestinal immune system, and abnormal colonization of the intestinal microbiota. Researchers have shown considerable interest in exploring the therapeutic potential of the constituents present in human breast milk (HBM) for treating NEC. HBM contains numerous bioactive components, such as exosomes, growth factors, and oligosaccharides. However, the precise mechanisms by which HBM exerts its protective effects against NEC remain incompletely understood. In this study, our objective was to comprehensively review the bioactive substances present in HBM, aiming to facilitate the development of novel therapeutic strategies for NEC.

The Impact of Stress, Microbial Dysbiosis, and Inflammation on Necrotizing Enterocolitis

Necrotizing enterocolitis (NEC) is the leading cause of intestinal morbidity and mortality in neonates. A large body of work exists; however, the pathogenesis of NEC remains poorly understood. Numerous predictors have been implicated in the development of NEC, with relatively less emphasis on maternal factors. Utilizing human tissue plays a crucial role in enhancing our comprehension of the underlying mechanisms accountable for this devastating disease. In this review, we will discuss how maternal stress affects the pathogenesis of NEC and how changes in the intestinal microbiome can influence the development of NEC. We will also discuss the results of transcriptomics-based studies and analyze the gene expression changes in NEC tissues and other molecular targets associated with the pathogenesis of NEC.

Clinical and Growth Correlates of Retinopathy of Prematurity in Preterm infants with Surgical Necrotizing Enterocolitis and intestinal Perforation

Background

we sought to determine the clinical and growth parameters associated with retinopathy of prematurity (ROP) in infants with necrotizing enterocolitis (NEC) and spontaneous ileal perforation (SIP).

Methods

Retrospective cohort study comparing clinical information before and following NEC/SIP onset in neonates with and without severe ROP (Type 1 and 2).

Results

Those with severe ROP (32/109, 39.5%) had lower GA, BW, chorioamnionitis, later median onset of ROP diagnosis and received Penrose drain and had higher AKI, poor weight z scores, poor linear growth, longer duration of ventilation and higher FIo2 than those without ROP following NEC/SIP. The GA and diagnosis at later age remained significant for any ROP on multi regression modelling.

Conclusion

The surgical NEC/SIP infants with severe ROP were more likely to be younger, smaller, had AKI, had higher oxygen exposure and poor weight gain and linear growth than those without severe ROP.

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.

Gut Microbiome-Brain Axis as an Explanation for the Risk of Poor Neurodevelopment Outcome in Preterm Infants with Necrotizing Enterocolitis

Necrotizing Enterocolitis (NEC) is characterized by an inflammation of intestinal tissue that primarily affects premature infants. It is the most common and devastating gastrointestinal morbidity of prematurity, but beyond intestinal morbidity, this condition has also been associated with an increased risk of neurodevelopmental delays that persist beyond infancy. Prematurity, enteral feeding, bacterial colonization, and prolonged exposure to antibiotics are all risk factors that predispose preterm infants to NEC. Interestingly, these factors are all also associated with the gut microbiome. However, whether or not there is a connection between the microbiome and the risk of neurodevelopmental delays in infants after NEC is still an emerging area of research. Furthermore, how microbes in the gut could impact a distant organ such as the brain is also poorly understood. In this review, we discuss the current understanding of NEC and the role of the gut microbiome-brain axis in neurodevelopmental outcomes after NEC. Understanding the potential role of the microbiome in neurodevelopmental outcomes is important as the microbiome is modifiable and thus offers the hope of improved therapeutic options. We highlight the progress and limitations in this field. Insights into the gut microbiome-brain axis may offer potential therapeutic approaches to improve the long-term outcomes of premature infants.

Screening inflammatory protein biomarkers on premature infants with necrotizing enterocolitis

OBJECTIVE

This study aimed to explore potential inflammatory biomarkers for early prediction of necrotizing enterocolitis (NEC) in premature infants.

METHODS

Plasma samples were collected from premature infants with NEC (n = 30), sepsis (n = 29), and controls without infection (n = 29). The 92 inflammatory-related proteins were assessed via high-throughput OLINK proteomics platform.

RESULTS

There were 11 inflammatory proteins that significate differences (p < 0.05) among NEC, sepsis and control preterm infants, which include IL-8, TRAIL, IL-24, MMP-10, CCL20, CXCL1, OPG, TSLP, MCP-4, TNFSF14 and LIF. A combination of these 11 proteins could serve as differential diagnosis between NEC and control infants (AUC = 0.972), or between NEC and sepsis infants (AUC = 0.881). Furthermore, the combination of IL-8, OPG, MCP-4, IL-24, LIF and CCL20 could distinguish Stage II and III of NEC (AUC = 0.977). Further analysis showed the combination of IL-8, IL-24 and CCL20 have the best prediction value for NEC and control (AUC = 0.947), NEC and sepsis (AUC = 0.838) and different severity of NEC (AUC = 0.842).

CONCLUSION

Inflammatory proteins were different expressed in premature infants with NEC compared with controls or sepsis. Combining these proteins provide a higher diagnostic potential for preterm NEC infants.

Systemic Cytokines in Retinopathy of Prematurity

Retinopathy of prematurity (ROP), a vasoproliferative vitreoretinal disorder, is the leading cause of childhood blindness worldwide. Although angiogenic pathways have been the main focus, cytokine-mediated inflammation is also involved in ROP etiology. Herein, we illustrate the characteristics and actions of all cytokines involved in ROP pathogenesis. The two-phase (vaso-obliteration followed by vasoproliferation) theory outlines the evaluation of cytokines in a time-dependent manner. Levels of cytokines may even differ between the blood and the vitreous. Data from animal models of oxygen-induced retinopathy are also valuable. Although conventional cryotherapy and laser photocoagulation are well established and anti-vascular endothelial growth factor agents are available, less destructive novel therapeutics that can precisely target the signaling pathways are required. Linking the cytokines involved in ROP to other maternal and neonatal diseases and conditions provides insights into the management of ROP. Suppressing disordered retinal angiogenesis via the modulation of hypoxia-inducible factor, supplementation of insulin-like growth factor (IGF)-1/IGF-binding protein 3 complex, erythropoietin, and its derivatives, polyunsaturated fatty acids, and inhibition of secretogranin III have attracted the attention of researchers. Recently, gut microbiota modulation, non-coding RNAs, and gene therapies have shown promise in regulating ROP. These emerging therapeutics can be used to treat preterm infants with ROP.

Shaping infant development from the inside out: Bioactive factors in human milk

Human breast milk is the optimal nutrition for all infants and is comprised of many bioactive and immunomodulatory components. The components in human milk, such as probiotics, human milk oligosaccharides (HMOs), extracellular vesicles, peptides, immunoglobulins, growth factors, cytokines, and vitamins, play a critical role in guiding neonatal development beyond somatic growth. In this review, we will describe the bioactive factors in human milk and discuss how these factors shape neonatal immunity, the intestinal microbiome, intestinal development, and more from the inside out.

Necrotizing enterocolitis, gut microbes, and sepsis

Necrotizing enterocolitis (NEC) is a devastating disease in premature infants and the leading cause of death and disability from gastrointestinal disease in this vulnerable population. Although the pathophysiology of NEC remains incompletely understood, current thinking indicates that the disease develops in response to dietary and bacterial factors in the setting of a vulnerable host. As NEC progresses, intestinal perforation can result in serious infection with the development of overwhelming sepsis. In seeking to understand the mechanisms by which bacterial signaling on the intestinal epithelium can lead to NEC, we have shown that the gram-negative bacterial receptor toll-like receptor 4 is a critical regulator of NEC development, a finding that has been confirmed by many other groups. This review article provides recent findings on the interaction of microbial signaling, the immature immune system, intestinal ischemia, and systemic inflammation in the pathogenesis of NEC and the development of sepsis. We will also review promising therapeutic approaches that show efficacy in pre-clinical studies.

Clinical impact of analgesic-sedative agents and peri-operative clinical status on white matter brain injury in preterm infants following surgical NEC

BACKGROUND

The potential influence of exposure to analgesic-sedative agents (ASA) before, during, and after surgical NEC and peri-operative clinical status on white matter injury (WMI) in preterm infants has not been fully defined, and a comprehensive evaluation may inform future research and clinical interventions.

METHODS

A retrospective study comparing ASA exposure before/during /after surgical NEC and peri-operative clinical status in neonates with and without WMI.

RESULTS

Infants with any WMI (grade 2-4, n = 36/67, 53.7%) had a higher number of surgical procedures receiving ASA (5 [IQR: 3, 8] vs. 3 [2, 4]; p = 0.002) and had a longer duration of hypotension during their first (48.0 hours [26.0, 48.0] vs. 15.5 [6, 48]; p = 0.009) and second surgery (20 hours [0, 48h] vs. 0 [0, 22]; p = 0.017), received more hydrocortisone (35% vs.13.3%,p = 0.04) than those without any WMI. There were no differences in fentanyl/morphine/midazolam exposure before/during/after the NEC onset in the two groups.Infants with severe WMI (19/67, 28.3%, grade 3/4) had a higher incidence of AKI (P = 0.004), surgical morbidity (p = 0.047), more surgical procedures (6.5 [3, 10] vs. 4 [2, 5]; p = 0.012), and received higher mean fentanyl doses(p = 0.03) from birth until NEC onset than those without severe WMI. The univariate associations between these factors and severe WMI remained insignificant after multivariable logistic regression.

CONCLUSION

Infants with WMI had more surgical procedures receiving ASA and had a longer duration of hypotension during surgeries. A large multicenter prospective study is needed to understand the full impact of ASA.

Utility of transforming growth factor beta-1 in diagnosis of neonatal necrotizing enterocolitis

Necrotizing enterocolitis (NEC) yet remains a leading cause of morbidity and mortality in premature infants. The developmental deficiency of transforming growth factor-Beta (TGF-β) in the intestine is a risk factor for NEC in premature infants.We aimed to investigate the potential utility of serum TGF-β1 in the early diagnosis and severity assessment of NEC. This prospective case-control study was conducted on 102 VLBW neonates aging less than 32 weeks and weighing less than 1500 gm. They were divided into NEC group of 52 preterm neonates with symptoms and signs of NEC and 50 age and sex-matched neonates without NEC as a control group. All neonates underwent full medical history taking, clinical examination, radiological and laboratory investigations including CBC, CRP, fecal occult blood, and serum TGF-β1. Serum TGF-β1 was tested in NEC patients at the onset of symptoms and signs and 7 days later. Serum TGF-β1 was significantly lower in NEC patients at the onset of symptoms than the control group (P = 0.004) while after 7 days of onset serum TGF-β1 was significantly higher than at the onset of symptoms (P < 0.001). In NEC patients with stage I, TGF-β1 was significantly higher than in NEC patients with stage ≥II (P = 0.027).In conclusion serum TGF-β1 is downregulated in neonatal necrotizing enterocolitis and can be used as a useful biomarker for early diagnosis of NEC and to assess disease severity.

Chorioamnionitis-exposure alters serum cytokine trends in premature neonates

OBJECTIVES

Determine if chronologic age and/or chorioamnionitis exposure alter normal serum cytokine and chemokine levels in uninfected preterm neonates during their initial NICU stay.

STUDY DESIGN

A 7-plex immunoassay measured levels of serum IL-1β, IL-6, IL-8, IL-10, TNF-α, CCL2, and CCL3 longitudinally from chorioamnionitis-exposed and unexposed preterm neonates under 33 weeks' gestation.

RESULTS

Chorioamnionitis-exposed and unexposed preterm neonates demonstrated differences in the trends of IL-1β, IL-6, IL-8, IL-10, TNF-α, and CCL2 over the first month of life. The unexposed neonates demonstrated elevated levels of these inflammatory markers in the first two weeks of life with a decrease by the third week of life, while the chorioamnionitis-exposed neonates demonstrated differences over time without a predictable pattern. Chorioamnionitis-exposed and unexposed neonates demonstrated altered IL-10 and TNF-α trajectories over the first twelve weeks of life.

CONCLUSION

Chorioamnionitis induces a state of immune dysregulation in preterm neonates that persists beyond the immediate neonatal period.

Clinical impact of severe acute kidney injury on post-operative and brain injury outcomes in preterm infants following surgical necrotizing enterocolitis

BACKGROUND

To evaluate post-operative outcomes and white matter injury (WMI) using brain MRI at term equivalent in neonates with and without severe acute kidney injury (AKI) following surgical necrotizing enterocolitis (NEC).

METHODS

A retrospective cohort study comparing neonates with severe (Stage 2/3) vs. other (no AKI/Stage 1) AKI using KDIGO classification with multivariable models assessing this association in the context of multiple systemic comorbidities.

RESULTS

Of 103 neonates with surgical NEC, 60 (58%) had severe AKI. Those with severe AKI had lower birth weight (BW; 715 vs. 950 g; p = .023), more frequently treated with indomethacin (18.3 vs. 2.4%); p = .014), higher CRP levels at 24 h after NEC onset (14.4 [6.4-19.8] vs. 4.8 [1.6-13.4]; p = .005), higher presence of cholestasis (73.3 vs. 51.2%); p = .023), later age of NEC onset (14 vs. 7 d); p = .004), longer length of bowel resected (14.9 vs. 4.3 cm); p = .011), longer post-operative ileus days (14 vs. 9 d); p < .001), longer post-operative days at starting enteral feedings (15 vs. 10 d; p < .001), longer days of attainment of full enteral feedings (75 vs. 44.5 d; p = .008) and longer length of stay (140.5 vs. 94 d; p = .028) compared to those without severe AKI. Compared to infants without AKI by serum creatinine, those with AKI had significantly more cases of white matter abnormality (WMA; 90 vs. 36.6%; p < .001) and retinopathy of prematurity (63.9 vs. 35.3%; p = .017). In addition, the presence of AKI Stage 2 and 3 by serum creatinine was independently associated with higher odds of sustaining severe WMI level on an ordinal scale (OR = 6.2; 95% CI = (1.1-35.5); p = .041).

CONCLUSIONS

Neonates with severe AKI following surgical NEC were more likely to experience longer post-operative morbidity and higher WMI by MRI at term.

Supplementation with a probiotic mixture accelerates gut microbiome maturation and reduces intestinal inflammation in extremely preterm infants

Probiotics are increasingly administered to premature infants to prevent necrotizing enterocolitis and neonatal sepsis. However, their effects on gut microbiome assembly and immunity are poorly understood. Using a randomized intervention trial in extremely premature infants, we tested the effects of a probiotic product containing four strains of Bifidobacterium species autochthonous to the infant gut and one Lacticaseibacillus strain on the compositional and functional trajectory of microbiome. Daily administration of the mixture accelerated the transition into a mature, term-like microbiome with higher stability and species interconnectivity. Besides infant age, Bifidobacterium strains and stool metabolites were the best predictors of microbiome maturation, and structural equation modeling confirmed probiotics as a major determinant for the trajectory of microbiome assembly. Bifidobacterium-driven microbiome maturation was also linked to an anti-inflammatory intestinal immune milieu. This demonstrates that Bifidobacterium strains are ecosystem engineers that lead to an acceleration of microbiome maturation and immunological consequences in extremely premature infants.

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.

Brain injury in preterm infants with surgical necrotizing enterocolitis: clinical and bowel pathological correlates

BACKGROUND

The objective of this study was to determine the risk factors and outcomes of white matter brain injury (WMBI) on magnetic resonance imaging (MRI) at term-equivalent age in infants with surgical necrotizing enterocolitis (NEC).

METHODS

This retrospective study compared clinical/pathological information between infants with and those without WMBI.

RESULTS

Out of 69 infants with surgical NEC, 17 (24.6%) had mild WMBI, 13 (18.8%) had moderate WMBI, and six (8.7%) had severe WMBI on the brain MRI. Several clinical factors (gestational age, more red blood cell (RBC) transfusions before NEC onset, pneumoperitoneum, earlier NEC onset age, postoperative ileus, acute kidney injury (AKI) by serum creatinine, postnatal steroids, hospital stay) and histopathological findings (necrosis, hemorrhage) had univariate associations with WMBI. Associations with RBC transfusion (odds ratio (OR) 23.6 [95% confidence interval (CI): 4.73-117.97]; p = 0.0001), age at NEC onset (OR 0.30 [95%CI: 0.11-0.84]; p = 0.021), necrosis (OR 0.10 [95%CI: 0.01-0.90]; p = 0.040), and bowel hemorrhage (OR 7.79 [95%CI: 2.19-27.72]; p = 0.002) persisted in multivariable association with grade 3-4 WMBI. The infants with WMBI had lower mean motor, cognitive, language scores, and higher ophthalmic morbidity at 2 years of age.

CONCLUSIONS

The WMBI was most likely associated with earlier NEC onset, higher RBC transfusions, and less necrosis and greater hemorrhage lesions on intestinal pathology in preterm infants with surgical NEC.

IMPACT

In preterm infants with surgical NEC, brain MRI showed injury in the white matter in 52%, gray matter in 10%, and cerebellar region in 30%. Preterm infants with severe WMBI (grade 3-4) had less necrosis and greater hemorrhagic lesions on histopathology of the bowel. Preterm infants with WMBI were more likely to have a more severe postoperative course, AKI, and longer length of hospitalization. Neuroprotective strategies to prevent brain injury in preterm infants with surgical NEC are needed with the goal of improving the neurodevelopmental outcomes.

Intestinal Epithelial Barrier Function and Necrotizing Enterocolitis

Necrotizing enterocolitis (NEC) is a major cause of morbidity and mortality in premature infants. NEC is characterized by intestinal tissue inflammation and necrosis. The intestinal barrier is altered in NEC, which potentially contributes to its pathogenesis by promoting intestinal bacterial translocation and stimulating the inflammatory response. In premature infants, many components of the intestinal barrier are immature. This article reviews the different components of the intestinal barrier and how their immaturity contributes to intestinal barrier dysfunction and NEC.

Biomarkers of Necrotizing Enterocolitis: The Search Continues

Necrotizing enterocolitis (NEC) is the most common gastrointestinal (GI) emergency in the neonatal intensive care unit. Despite advances in medical care, mortality and morbidity from NEC have not changed. This is likely due to the lack of a clear understanding of this multifactorial disease, and reliable biomarkers for accurate diagnosis of NEC. Currently, the diagnosis of NEC is made by a combination of nonspecific clinical signs, symptoms, and radiological findings. Though biomarkers have been studied extensively, none offer an acceptable sensitivity or specificity to be used. This review will focus on the available literature on biomarkers for preterm NEC, acknowledging the limitations in studies including the variability of inclusion criteria, and most importantly, the lack of gold standard case definition for NEC.

Necrotizing Enterocolitis: Clinical Features, Histopathological Characteristics, and Genetic Associations

Necrotizing enterocolitis (NEC) is an inflammatory bowel necrosis seen in premature infants. Although the etiopathogenesis of NEC is unclear, genetic factors may alter a patient's susceptibility, clinical course, and outcomes. This review draws from existing studies focused on individual genes and others based on microarray-based high-throughput discovery techniques. We have included evidence from our own studies and from an extensive literature search in the databases PubMed, EMBASE, and Scopus. To avoid bias in the identification of studies, keywords were short-listed a priori from anecdotal experience and PubMed's Medical Subject Heading (MeSH) thesaurus.

The potential role of adherence factors in probiotic function in the gastrointestinal tract of adults and pediatrics: a narrative review of experimental and human studies

Numerous studies point to the important role of probiotic bacteria in gastrointestinal health. Probiotics act through mechanisms affecting enteric pathogens, epithelial barrier function, immune signaling, and conditioning of indigenous microbiota. Once administered, probiotics reach the gastrointestinal tract and interact with the host through bacterial surface molecules, here called adhesion factors, which are either strain- or specie-specific. Probiotic adhesion, through structural adhesion factors, is a mechanism that facilitates persistence within the gastrointestinal tract and triggers the initial host responses. Thus, an understanding of specific probiotic adhesion mechanisms could predict how specific probiotic strains elicit benefits and the potential of adherence factors as a proxy to predict probiotic function. This review summarizes the present understanding of probiotic adherence in the gastrointestinal tract. It highlights the bacterial adhesion structure types, their molecular communication with the host and the consequent impact on intestinal diseases in both adult and pediatric populations. Finally, we discuss knockout/isolation studies as direct evidence for adhesion factors conferring anti-inflammatory and pathogen inhibition properties to a probiotic.What is known: Probiotics can be used to treat clinical conditions.Probiotics improve dysbiosis and symptoms.Clinical trials may not confirm in vitro and animal studies.What is new: Adhesion structures may be important for probiotic function.Need to systematically determine physical characteristics of probiotics before selecting for clinical trials.Probiotics may be genetically engineered to add to clinical efficacy.

Vagal Tone and Proinflammatory Cytokines Predict Feeding Intolerance and Necrotizing Enterocolitis Risk

BACKGROUND

Necrotizing enterocolitis (NEC) is the leading cause of death due to gastrointestinal disease in preterm neonates; yet, clinicians lack reliable and noninvasive predictive tools.

PURPOSE

We aimed to test that diminished high-frequency heart rate variability (HF-HRV) and elevated levels of proinflammatory cytokines would have utility in NEC prediction.

METHODS

In this multisite prospective study, we enrolled 250 preterm (26-34 weeks' postmenstrual age [PMA]) neonates with physiological stability at 72 hours of life. HRV was measured noninvasively using electrocardiograhic data from standardized cardiorespiratory monitors at postnatal week 1 of life and weekly thereafter until 35 weeks' PMA or discharge; blood was collected for cytokines at postnatal weeks 1 and 3. NEC was diagnosed via Modified Bell's Staging Criteria.

RESULTS

HF-HRV was decreased at weeks 1 and 2 in neonates (47% females) who developed feeding intolerance or stage 2+ NEC. In addition, these neonates displayed elevated levels of IL-8 at week 1 and increased levels of IL-1β, IL-6, TNF-α, and IL-8 at week 3 of life. Low HF-HRV was associated with elevated IL-6 or IL-8 levels at weeks 1 and 3 of life. Logistic regression indicated that only HF-HRV was a significant predictor of feeding intolerance or NEC development.

IMPLICATIONS FOR PRACTICE AND RESEARCH

HRV is a promising noninvasive modality for NEC risk detection. The association of low HF-HRV with elevated proinflammatory cytokines provides evidence for a putative role of the vagal cholinergic pathway in NEC pathogenesis. Future studies should focus on application of these techniques to test clinical therapeutics.Video Abstract available at https://journals.lww.com/advancesinneonatalcare/Pages/videogallery.aspx?autoPlay=false&videoId=54.

Cytotoxic Lactalbumin-Oleic Acid Complexes in the Human Milk Diet of Preterm Infants

Frozen storage is necessary to preserve expressed human milk for critically ill and very preterm infants. Milk pasteurization is essential for donor milk given to this special population. Due to these storage and processing conditions, subtle changes occur in milk nutrients. These changes may have clinical implications. Potentially, bioactive complexes of unknown significance could be found in human milk given to preterm infants. One such complex, a cytotoxic α-lactalbumin-oleic acid complex named "HAMLET," (Human Alpha-Lactalbumin Made Lethal to Tumor cells) is a folding variant of alpha-lactalbumin that is bound to oleic acid. This complex, isolated from human milk casein, has specific toxicity to both carcinogenic cell lines and immature non-transformed cells. Both HAMLET and free oleic acid trigger similar apoptotic mechanisms in tissue and stimulate inflammation via the NF-κB and MAPK p38 signaling pathways. This protein-lipid complex could potentially trigger various inflammatory pathways with unknown consequences, especially in immature intestinal tissues. The very preterm population is dependent on human milk as a medicinal and broadly bioactive nutriment. Therefore, HAMLET's possible presence and bioactive role in milk should be addressed in neonatal research. Through a pediatric lens, HAMLET's discovery, formation and bioactive benefits will be reviewed.

Impact of Docosahexaenoic acid supplementation on proinflammatory cytokines release and the development of Necrotizing enterocolitis in preterm Neonates: A randomized controlled study

INTRODUCTION

Preterm neonates have under-developed immune-regulatory system; consequently, there is a risk for developing chronic inflammation. Necrotizing enterocolitis (NEC) is an acute devastating neonatal intestinal inflammatory disorder. Due to the obscure multifactorial etiology, early diagnosis and effective treatment of NEC are limited. Consequently, effective strategies in the prevention of NEC, including nutritional approaches, are critically needed. The current study was conducted to assess the potential immunomodulatory effect of Docosahexaenoic Acid (DHA) supplementation in preterm neonates at neonatal intensive care unit (NICU) and subsequently its effect on preventing or reducing NEC incidence.

METHODS

This was a prospective randomized controlled study. A total of 67 neonates, with gestational age equal or less than 32 weeks at birth and weight less than or equal 1500 g, were randomly assigned to either DHA group or the control group. Modified Bell's staging criteria for NEC was used as an objective tool for diagnosis and staging of NEC. Levels of Interleukin 1 beta (IL-1β) were measured at baseline and after 10 days. Mortality and NICU length of stay (LOS) were also monitored.

RESULTS

Thirty neonates of each group completed the study. A statistically significant difference was observed between the two groups regarding diagnosis and staging of NEC (p = 0.0001). There was also a statistically significant difference between DHA group 22(73.3), 95% CI [55.9, 86.5] and the control group 8 (26.7), 95% CI [13.5, 44.1] in the percentage change in IL-1β levels (p = 0.0001).A statistically significant association was found between IL and 1 β change and NEC diagnosis (p = 0.001). NICU LOS was significantly lower among DHA group 21.63 ± 6.67 compared to the control group 25.07 ± 4.67 (p = 0.025). Mortality n (%) among the control group 4 (11.8) was higher than DHA group 3 (9.1), however, no significant difference was detected (p = 1.0).

CONCLUSION

Findings of this study suggest that enteral DHA supplementation can reduce NEC incidence in preterm neonates through its immunoregulatory effect that modulates production of regulatory cytokines.Trial registration: Registered at clinical trials.gov (NCT03700957), 6 October 2018.

Necrotizing enterocolitis and the gut-lung axis

The recently recognized connection between the gut microbiota and pulmonary disease has been termed the gut-lung axis. However, broader connections link the gut and the lungs and these organ systems are tightly interrelated in both homeostasis and disease. This concept is often ignored in the compartmentalized treatment of pulmonary or gastrointestinal disease. In newborns, the most severe gastrointestinal complication of prematurity, necrotizing enterocolitis, and the most severe pulmonary complication, bronchopulmonary dysplasia, both produce significant systemic morbidity. In this review, we highlight the often neglected pathophysiology of the gut-lung axis contributes to increased risk of bronchopulmonary dysplasia in premature infants with necrotizing enterocolitis.

Role of macrophages in fetal development and perinatal disorders

In the fetus and the neonate, altered macrophage function has been implicated not only in inflammatory disorders but also in developmental abnormalities marked by altered onset, interruption, or imbalance of key structural changes. The developmental role of macrophages were first noted nearly a century ago, at about the same time when these cells were being identified as central effectors in phagocytosis and elimination of microbes. Since that time, we have made considerable progress in understanding the diverse roles that these cells play in both physiology and disease. Here, we review the role of fetal and neonatal macrophages in immune surveillance, innate immunity, homeostasis, tissue remodeling, angiogenesis, and repair of damaged tissues. We also discuss the possibility of therapeutic manipulation of the relative abundance and activation status of macrophage subsets in various diseases. This article combines peer-reviewed evidence from our own studies with results of an extensive literature search in the databases PubMed, EMBASE, and Scopus. IMPACT: We have reviewed the structure, differentiation, and classification of macrophages in the neonatal period. Neonatal macrophages are derived from embryonic, hepatic, and bone marrow precursors. Macrophages play major roles in tissue homeostasis, innate immunity, inflammation, tissue repair, angiogenesis, and apoptosis of various cellular lineages in various infectious and inflammatory disorders. Macrophages and related inflammatory mediators could be important therapeutic targets in several neonatal diseases.

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.

Cytokine therapy in necrotizing enterocolitis: A promising treatment for preterm infants

Necrotizing enterocolitis (NEC) is an intestinal disorder that disproportionately affects premature infants and lacks in effective therapeutics. Mihi and colleagues1 demonstrated that the cytokine interleukin-22 promotes intestinal epithelial regeneration and reduces disease severity in an experimental model of NEC.

Enteral Feeding Interventions in the Prevention of Necrotizing Enterocolitis: A Systematic Review of Experimental and Clinical Studies

Necrotizing enterocolitis (NEC), which is characterized by severe intestinal inflammation and in advanced stages necrosis, is a gastrointestinal emergency in the neonate with high mortality and morbidity. Despite advancing medical care, effective prevention strategies remain sparse. Factors contributing to the complex pathogenesis of NEC include immaturity of the intestinal immune defense, barrier function, motility and local circulatory regulation and abnormal microbial colonization. Interestingly, enteral feeding is regarded as an important modifiable factor influencing NEC pathogenesis. Moreover, breast milk, which forms the currently most effective prevention strategy, contains many bioactive components that are known to support neonatal immune development and promote healthy gut colonization. This systematic review describes the effect of different enteral feeding interventions on the prevention of NEC incidence and severity and the effect on pathophysiological mechanisms of NEC, in both experimental NEC models and clinical NEC. Besides, pathophysiological mechanisms involved in human NEC development are briefly described to give context for the findings of altered pathophysiological mechanisms of NEC by enteral feeding interventions.

Use of omic technologies in early life gastrointestinal health and disease: from bench to bedside

Introduction: At birth, the gastrointestinal (GI) tract is colonized by a complex community of microorganisms, forming the basis of the gut microbiome. The gut microbiome plays a fundamental role in host health, disorders of which can lead to an array of GI diseases, both short and long term. Pediatric GI diseases are responsible for significant morbidity and mortality, but many remain poorly understood. Recent advancements in high-throughput technologies have enabled deeper profiling of GI morbidities. Technologies, such as metagenomics, transcriptomics, proteomics and metabolomics, have already been used to identify associations with specific pathologies, and highlight an exciting area of research. However, since these diseases are often complex and multifactorial by nature, reliance on a single experimental approach may not capture the true biological complexity. Therefore, multi-omics aims to integrate singular omic data to further enhance our understanding of disease.Areas covered: This review will discuss and provide an overview of the main omic technologies that are used to study complex GI pathologies in early life.Expert opinion: Multi-omic technologies can help to unravel the complexities of several diseases during early life, aiding in biomarker discovery and enabling the development of novel therapeutics and augment predictive models.

Prenatal Immunity and Influences on Necrotizing Enterocolitis and Associated Neonatal Disorders

Prior to birth, the neonate has limited exposure to pathogens. The transition from the intra-uterine to the postnatal environment initiates a series of complex interactions between the newborn host and a variety of potential pathogens that persist over the first few weeks of life. This transition is particularly complex in the case of the premature and very low birth weight infant, who may be susceptible to many disorders as a result of an immature and underdeveloped immune system. Chief amongst these disorders is necrotizing enterocolitis (NEC), an acute inflammatory disorder that leads to necrosis of the intestine, and which can affect multiple systems and have the potential to result in long term effects if the infant is to survive. Here, we examine what is known about the interplay of the immune system with the maternal uterine environment, microbes, nutritional and other factors in the pathogenesis of neonatal pathologies such as NEC, while also taking into consideration the effects on the long-term health of affected children.

The impact of indole-3-lactic acid on immature intestinal innate immunity and development: a transcriptomic analysis

An excessive intestinal inflammatory response may have a role in the pathogenesis of necrotizing enterocolitis (NEC) in very preterm infants. Indole-3-lactic acid (ILA) of breastmilk tryptophan was identified as the anti-inflammatory metabolite involved in probiotic conditioned media from Bifidobacteria longum subsp infantis. This study aimed to explore the molecular endocytic pathways involved in the protective ILA effect against inflammation. H4 cells, Caco-2 cells, C57BL/6 pup and adult mice were used to compare the anti-inflammatory mechanisms between immature and mature enterocytes in vitro and in vivo. The results show that ILA has pleiotropic protective effects on immature enterocytes including anti-inflammatory, anti-viral, and developmental regulatory potentials in a region-dependent and an age-dependent manner. Quantitative transcriptomic analysis revealed a new mechanistic model in which STAT1 pathways play an important role in IL-1β-induced inflammation and ILA has a regulatory effect on STAT1 pathways. These studies were validated by real-time RT-qPCR and STAT1 inhibitor experiments. Different protective reactions of ILA between immature and mature enterocytes indicated that ILA's effects are developmentally regulated. These findings may be helpful in preventing NEC for premature infants.

Relationship Between Milk Fat Globule-Epidermal Growth Factor 8 and Intestinal Cytokines in Infants Born Preterm

OBJECTIVES

To investigate the relationships between dietary intake and fecal concentrations of milk fat globule-epidermal growth factor 8 (MFG-E8), and between fecal concentrations of MFG-E8 and markers of intestinal inflammation in infants born preterm.

STUDY DESIGN

Fecal samples were collected daily and enteral feedings were sampled weekly. MFG-E8 in enteral feedings and feces, and cytokine concentrations in feces were quantified by enzyme-linked immunosorbent assay.

RESULTS

Milk MFG-E8 concentrations were significantly greater in unfortified mother's own milk (MOM) and MOM with human milk fortifier than either donor human milk or preterm formula. MFG-E8 concentrations in fecal samples were positively correlated with MFG-E8 concentrations in respective milks. High MFG-E8 exposure (≥60 mL/kg/day of feedings that include MOM or MOM with human milk fortifier) was associated with lower concentrations of proinflammatory cytokines (interleukin-8, tumor necrosis factor-α, and monocyte chemoattractant protein-1) and higher concentrations of the anti-inflammatory cytokine interleukin-4 in feces, compared with low MFG-E8 exposure.

CONCLUSIONS

Infants born preterm who were fed MOM had greater concentrations of MFG-E8 and lower concentrations of proinflammatory cytokines in fecal samples than other diets or no feedings. These data further support the protective role of MOM, possibly because of MFG-E8, against intestinal inflammation.

Impact of Probiotic B. infantis EVC001 Feeding in Premature Infants on the Gut Microbiome, Nosocomially Acquired Antibiotic Resistance, and Enteric Inflammation

Background: Preterm birth is a major determinant of neonatal survival and morbidity, but the gut microbiome and associated enteric inflammation are also key factors in neonatal development and the risk of associated morbidities. We prospectively and longitudinally followed two cohorts of preterm infants, one of which was fed activated Bifidobacterium longum subsp. infantis (B. infantis) EVC001 8 × 109 CFU daily, and the other was not fed a probiotic. Hospital feeding protocol assigned all infants born at <1500 g and/or < 32 weeks corrected gestational age to the probiotic feeding protocol, whereas infants born at >1500 g and/or >32 weeks corrected gestational age were not fed a probiotic. Fecal samples were opportunistically collected from 77 infants throughout the hospital stay, and subjected to shotgun metagenomic sequencing and quantification of enteric inflammation. De-identified metadata was collected from patient medical records. Results: The gut microbiome of preterm infants was typified by a high abundance of Enterobacteriaceae and/or Staphylococcaceae, and multivariate modeling identified the probiotic intervention, rather than degree of prematurity, day of life, or other clinical interventions, as the primary source of change in the gut microbiome. Among infants fed B. infantis EVC001, a high abundance of total Bifidobacteriaceae developed rapidly, the majority of which was B. infantis confirmed via subspecies-specific qPCR. Associated with this higher abundance of Bifidobacteriaceae, we found increased functional capacity for utilization of human milk oligosaccharides (HMOs), as well as reduced abundance of antibiotic resistance genes (ARGs) and the taxa that harbored them. Importantly, we found that infants fed B. infantis EVC001 exhibited diminished enteric inflammation, even when other clinical variables were accounted for using multivariate modeling. Conclusion: These results provide an important observational background for probiotic use in a NICU setting, and describe the clinical, physiological, and microbiome-associated improvements in preterm infants associated with B. infantis EVC001 feeding.