Prenatal Immunity and Influences on Necrotizing Enterocolitis and Associated Neonatal Disorders

Causal Relationships Between Leukocyte Subsets and Adverse Fetal Outcomes: A Mendelian Randomization Study

Background: The tolerance and dynamic regulation of the maternal immune system during pregnancy are pivotal for ensuring fetal health. Immune cell subsets play a complex and crucial role in this process, closely linked to the neonatal health status. Despite recognizing the significance of dysregulation in the quantity and activity of immune cells in neonatal disease occurrence, their specific roles remain elusive, resulting in a dearth of clinically viable interventions for immune-mediated neonatal diseases. Materials and Methods: Employing two-sample Mendelian randomization (MR) methodology, this study systematically investigated 446 leukocyte features (N = 500,675), including leukocyte subsets, absolute cell (AC) counts, and morphological parameters (MP) and their correlation with seven adverse fetal outcomes (N = 1,100,458), encompassing fetal growth restriction (FGR), preterm birth (PTB), neonatal jaundice (NNJ), digestive system disorders of fetus and newborn (DSDFN), hemorrhagic and hematological disorders of fetus and newborn (HDFN), respiratory distress of newborn (RDN), and transitory disorders of metabolism specific to fetus and newborn (TDMSFN). Results: The results unveiled significant causal relationships between 301 leukocyte subsets and these seven adverse fetal outcomes, with 259, 245, 15, 44, 11, 32, and 68 pairs of notable associations for each adverse outcome, respectively. Furthermore, the study highlighted potential pathogenic mechanisms underlying the mutual influence among neonatal diseases. MR results indicated FGR as a robustly correlated risk factor for PTB and NNJ and showed a reciprocal causal relationship between NNJ and FGR. PTB exhibited a positive correlation with HDFN. Conclusions: This study provided profound insights into the intricate regulatory mechanisms of leukocyte subsets in neonatal diseases, paving the way for new avenues in the diagnosis and treatment of associated disorders.

Initial surgery for spontaneous intestinal perforation in extremely low birth weight infants is not associated with mortality or in-hospital morbidities

OBJECTIVE

Determine short-term outcomes following peritoneal drain (PD), laparotomy (LAP) after PD (PD-LAP), and LAP in extremely low birth weight (ELBW) infants with spontaneous intestinal perforation (SIP).

STUDY DESIGN

ELBW infants with SIP were identified using the Children's Hospitals Neonatal Database. Mortality and length of stay (LOS) were compared among groups.

RESULTS

Of 729 SIP infants from 6/2010-12/2016, 383(53%) received PD, 61(8%) PD-LAP, and 285(39%) LAP. PD infants had lower GA at birth, at SIP diagnosis and upon admission than PD-LAP or LAP; and higher sepsis rates than LAP. Bivariate analysis and Kaplan-Meier survival estimates suggested PD had increased mortality vs. PD-LAP and LAP (27%, 11.5%, and 15.8% respectively, p < 0.001). However, surgical approach was not significantly associated with mortality in multivariable analysis accounting for GA and illness severity. LOS did not differ by surgical approach.

CONCLUSIONS

In ELBW infants with SIP, mortality, and LOS are independent of the initial surgical approach.

Progranulin mitigates intestinal injury in a murine model of necrotizing enterocolitis by suppressing M1 macrophage polarization

Neonatal necrotizing enterocolitis (NEC) is a critical digestive disorder frequently affecting premature infants. Characterized by intestinal inflammation caused by activated M1 macrophages, modulation of macrophage polarization is considered a promising therapeutic strategy for NEC. It has been demonstrated that the growth factor-like protein progranulin (PGRN), which plays roles in a number of physiological and pathological processes, can influence macrophage polarization and exhibit anti-inflammatory characteristics in a number of illnesses. However, its role in NEC is yet to be investigated. Our research showed that the levels of PGRN were markedly elevated in both human and animal models of NEC. PGRN deletion in mice worsens NEC by encouraging M1 polarization of macrophages and escalating intestinal damage and inflammation. Intravenous administration of recombinant PGRN to NEC mice showed significant survival benefits and protective effects, likely due to PGRN's ability to inhibit M1 polarization and reduce the release of pro-inflammatory factors. Our findings shed new light on PGRN's biological role in NEC and demonstrate its potential as a therapeutic target for the disease.

Assessment of inflammatory biomarkers to identify surgical/death necrotizing enterocolitis in preterm infants without pneumoperitoneum

BACKGROUND

Necrotizing enterocolitis (NEC) is a life-threatening disease that affects premature infants. However, the role of inflammatory biomarkers in identifying surgical/death NEC without pneumoperitoneum remains elusive.

PURPOSE

We aimed to verify the value of platelet-to-lymphocyte ratio (PLR) and the combination of white blood cell (WBC), absolute neutrophil count (ANC), absolute lymphocyte count (ALC), neutrophil lymphocyte ratio (NLR), PLR, C reactive protein (CRP) and procalcitonin (PCT) in predicting the severity of NEC, and to construct a model to differ surgically NEC from non-surgically NEC.

METHODS

A retrospective analysis was performed on 191 premature infants with NEC. Based on the inclusion and exclusion criteria, 90 infants with Stage II and IIIA NEC were enrolled in this study, including surgical/death NEC (n = 38) and medical NEC (n = 52). The values of inflammatory biomarkers were collected within 24 h of onset.

RESULTS

The univariate analysis revealed that the values of WBC (p = 0.040), ANC (p = 0.048), PLR (p = 0.009), CRP (p = 0.016) and PCT (p < 0.01) in surgical/death NEC cohort were significantly higher than medical NEC cohort. Binary multivariate logistic regression analysis indicates that ANC, PLR, CRP, and PCT are capable of distinguishing infants with surgical/death NEC, and the AUC of the regression equation was 0.79 (95% CI 0.64-0.89; sensitivity 0.63; specificity 0.88), suggesting the equation has a good discrimination.

IMPLICATIONS FOR PRACTICE AND RESEARCH

Elevated PLR is associated with severe inflammation in surgical/death NEC patients. The prediction modelling of combination of ANC, PLR, CRP and PCT can differentiate surgical/death NEC from infants with medical NEC, which may improve risk awareness and facilitate effective communication between nurses and clinicians. However, multicentre research is needed to verify these findings for better clinical management of NEC.

Subventricular zone stem cell niche injury is associated with intestinal perforation in preterm infants and predicts future motor impairment

Brain injury is highly associated with preterm birth. Complications of prematurity, including spontaneous or necrotizing enterocolitis (NEC)-associated intestinal perforations, are linked to lifelong neurologic impairment, yet the mechanisms are poorly understood. Early diagnosis of preterm brain injuries remains a significant challenge. Here, we identified subventricular zone echogenicity (SVE) on cranial ultrasound in preterm infants following intestinal perforations. The development of SVE was significantly associated with motor impairment at 2 years. SVE was replicated in a neonatal mouse model of intestinal perforation. Examination of the murine echogenic subventricular zone (SVZ) revealed NLRP3-inflammasome assembly in multiciliated FoxJ1+ ependymal cells and a loss of the ependymal border in this postnatal stem cell niche. These data suggest a mechanism of preterm brain injury localized to the SVZ that has not been adequately considered. Ultrasound detection of SVE may serve as an early biomarker for neurodevelopmental impairment after inflammatory disease in preterm infants.

Necrotizing enterocolitis: current understanding of the prevention and management

Necrotizing enterocolitis (NEC) is one of the diseases in neonates, with a high morbidity and mortality rate, especially in preterm infants. This review aimed to briefly introduce the latest epidemiology, susceptibility factors, and clinical diagnosis and presentation of NEC. We also organized new prevention strategies by risk factors according to different pathogeneses and then discussed new treatment methods based on Bell's staging and complications, and the classification of mild to high severity based on clinical and imaging manifestations. Such a generalization will help clinicians and researchers to gain a deeper understanding of the disease and to conduct more targeted classification, grading prevention, and exploration. We focused on prevention and treatment of the early and suspected stages of NEC, including the discovery of novel biomarkers and drugs to control disease progression. At the same time, we discussed its clinical application, future development, and shortcomings.

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

BACKGROUND

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

STUDY DESIGN

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

RESULTS

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

CONCLUSIONS

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

Identification of new biomarkers and immune infiltration characteristics of sepsis in very low birth weight infants

Sepsis is a life-threatening condition, especially in very low birth weight (VLBW) infants, and its pathogenesis remains unclear. Effective biomarkers need to be found to diagnose and treat the disease at an early stage. The Gene Expression Omnibus (GEO) database was screened and analyzed for differentially expressed genes (DEGs) in VLBW infants with sepsis. DEGs were then analyzed for functional enrichment. A weighted gene co-expression network analysis (WCGNA) was performed to identify the key modules and genes. The optimal feature genes (OFGs) were created using three machine learning algorithms. The single-sample Gene Set Enrichment Analysis (ssGSEA) scored the degree of immune cell enrichment between septic and control patients, and the correlation between OFGs and immune cells was evaluated. A total of 101 DEGs were identified between the sepsis and control samples. DEGs were mainly associated with immune responses and inflammatory signaling pathways in the enrichment analysis. In the WGCNA analysis, the MEturquoise module was significantly correlated with sepsis in VLBW infants (cor = 0.57, P < 0.001). By intersecting OFGs derived from three machine learning algorithms, two biomarkers were identified: glycogenin 1 (GYG1) and resistin (RETN). The area under the curves of GYG1 and RETN was greater than 0.97 in the testing set. The ssGSEA indicated immune cells infiltration in septic VLBW infants, and GYG1 and RETN revealed close correlations with immune cells. New biomarkers offer promising insights into the diagnosis and treatment of sepsis in VLBW infants.

A Nomogram for Predicting Surgical Timing in Neonates with Necrotizing Enterocolitis

OBJECTIVE

To explore the surgical risk variables in patients with necrotizing enterocolitis (NEC) and develop a nomogram model for predicting the surgical intervention timing of NEC.

METHODS

Infants diagnosed with NEC were enrolled in our study. We gathered information from clinical data, laboratory examinations, and radiological manifestations. Using LASSO (least absolute shrinkage and selection operator) regression analysis and multivariate logistic regression analysis, a clinical prediction model based on the logistic nomogram was developed. The performance of the nomogram model was evaluated using the receiver operating characteristic (ROC) curve, calibration curves, and decision curve analysis (DCA).

RESULTS

A surgical intervention risk nomogram based on hypothermia, absent bowel sounds, WBC > 20 × 10⁹/L or < 5 × 10⁹/L, CRP > 50 mg/L, pneumatosis intestinalis, and ascites was practical, had a moderate predictive value (AUC > 0.8), improved calibration, and enhanced clinical benefit.

CONCLUSIONS

This simple and reliable clinical prediction nomogram model can help physicians evaluate children with NEC in a fast and effective manner, enabling the early identification and diagnosis of children at risk for surgery. It offers clinical revolutionary value for the development of medical or surgical treatment plans for children with NEC.

Incidence of Healthcare-Associated Infections in a Neonatal Intensive Care Unit before and during the COVID-19 Pandemic: A Four-Year Retrospective Cohort Study

The COVID-19 pandemic may have had an impact on healthcare-associated infection (HAI) rates. In this study, we analyzed the occurrence of HAIs in a neonatal intensive care unit (NICU) of the Umberto I teaching hospital in Rome before and during the pandemic. All infants admitted from 1 March 2018 to 28 February 2022 were included and were divided into four groups according to their admission date: two groups before the pandemic (periods I and II) and two during the pandemic (periods III and IV). The association between risk factors and time-to-first event was analyzed using a multivariable Cox regression model. Over the four-year period, a total of 503 infants were included, and 36 infections were recorded. After adjusting for mechanical ventilation, birth weight, sex, type of delivery, respiratory distress syndrome, and previous use of netilmicin and fluconazole, the multivariable analysis confirmed that being hospitalized during the pandemic periods (III and IV) was the main risk factor for HAI acquisition. Furthermore, a change in the etiology of these infections was observed across the study periods. Together, these findings suggest that patient management during the pandemic was suboptimal and that HAI surveillance protocols should be implemented in the NICU setting promptly.

Assessment of Alcohol Exposure From Alcohol-Based Disinfectants Among Premature Infants in Neonatal Incubators in Japan

IMPORTANCE

The risk of premature infants in neonatal incubators exposed to evaporated alcohol from alcohol-based disinfectants (ABDs) is unknown.

OBJECTIVE

To assess alcohol concentrations in the peripheral blood of premature infants and neonatal incubators.

DESIGN, SETTING, AND PARTICIPANTS

A quality improvement study comparing 2 different populations before and after introduction of ABD practice (ABD-PRAC) was conducted in a neonatal intensive care unit of a single tertiary hospital in Japan. Participants included premature infants who were born before 34 weeks of gestational age and received medical care in neonatal incubators. The study consisted of 3 periods: (1) September 1, 2020, to August 1, 2021 (prospective observation of pre-ABD-PRAC, (2) August 2 to August 22, 2021 (introduction of ABD-PRAC to medical staff and parents in the neonatal intensive care unit), and (3) August 23, 2021, to March 31, 2022 (prospective observation of post-ABD-PRAC). No follow-up studies were initiated.

INTERVENTIONS

An ABD-PRAC that aimed to reduce alcohol evaporation from ABDs inside neonatal incubators was instituted: (1) place alcohol preps in the incubator just before use and remove them from the incubator as soon as possible and (2) withhold placing hands into the incubators until 60 seconds after using ABDs for disinfection (applied only to family members).

MAIN OUTCOMES AND MEASURES

Blood alcohol concentration and evaporated alcohol concentrations in neonatal incubators.

RESULTS

Disinfectant practice was assessed among 28 infants during the pre-ABD-PRAC (17 infants [10 girls]; median gestational age at birth, 29.4 [IQR, 26.3-30.3] weeks) and post-ABD-PRAC (11 infants [3 girls]; median gestational age at birth, 30.0 [IQR, 25.3-32.2] weeks) study periods. The median blood alcohol concentration was 7.0 (IQR, 5.4-9.3) mg/dL pre-ABD-PRAC and 4.2 (IQR, 2.5-7.2) mg/dL post-ABD-PRAC. The median evaporated alcohol concentration inside neonatal incubators during pre-ABD-PRAC during the day was 23.6 (IQR, 15.9-36.5) ppm and, at night, was 13.2 (IQR, 8.9-19.4) ppm; during post-ABD-PRAC, the concentration was 9.4 (IQR, 6.0-16.0) ppm during the day and 5.7 (IQR, 3.6-9.7) ppm at night. The introduction of ABD-PRAC at 22 weeks' corrected gestational age was associated with a lower blood alcohol concentration in premature infants: regression coefficient value, -8.3 (95% CI, -12.0 to -4.7).

CONCLUSIONS AND RELEVANCE

In this study, alcohol evaporated from ABDs was absorbed by premature infants in neonatal incubators. The findings suggest that introduction of ABD-PRAC was associated with lower alcohol concentrations in neonatal incubators and in the blood of premature infants.

Necrotizing Enterocolitis: The Role of Hypoxia, Gut Microbiome, and Microbial Metabolites

Necrotizing enterocolitis (NEC) is a life-threatening disease that predominantly affects very low birth weight preterm infants. Development of NEC in preterm infants is accompanied by high mortality. Surgical treatment of NEC can be complicated by short bowel syndrome, intestinal failure, parenteral nutrition-associated liver disease, and neurodevelopmental delay. Issues surrounding pathogenesis, prevention, and treatment of NEC remain unclear. This review summarizes data on prenatal risk factors for NEC, the role of pre-eclampsia, and intrauterine growth retardation in the pathogenesis of NEC. The role of hypoxia in NEC is discussed. Recent data on the role of the intestinal microbiome in the development of NEC, and features of the metabolome that can serve as potential biomarkers, are presented. The Pseudomonadota phylum is known to be associated with NEC in preterm neonates, and the role of other bacteria and their metabolites in NEC pathogenesis is also discussed. The most promising approaches for preventing and treating NEC are summarized.

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.

Gut-Brain cross talk: The pathogenesis of neurodevelopmental impairment in necrotizing enterocolitis

Necrotizing enterocolitis (NEC) is a devastating condition of multi-factorial origin that affects the intestine of premature infants and results in high morbidity and mortality. Infants that survive contend with several long-term sequelae including neurodevelopmental impairment (NDI)-which encompasses cognitive and psychosocial deficits as well as motor, vision, and hearing impairment. Alterations in the gut-brain axis (GBA) homeostasis have been implicated in the pathogenesis of NEC and the development of NDI. The crosstalk along the GBA suggests that microbial dysbiosis and subsequent bowel injury can initiate systemic inflammation which is followed by pathogenic signaling cascades with multiple pathways that ultimately lead to the brain. These signals reach the brain and activate an inflammatory cascade in the brain resulting in white matter injury, impaired myelination, delayed head growth, and eventual downstream NDI. The purpose of this review is to summarize the NDI seen in NEC, discuss what is known about the GBA, explore the relationship between the GBA and perinatal brain injury in the setting of NEC, and finally, highlight the existing research into possible therapies to help prevent these deleterious outcomes.

The administration of a pre-digested fat-enriched formula prevents necrotising enterocolitis-induced lung injury in mice

Necrotising enterocolitis (NEC) is a devastating gastrointestinal disease of prematurity that typically develops after the administration of infant formula, suggesting a link between nutritional components and disease development. One of the most significant complications that develops in patients with NEC is severe lung injury. We have previously shown that the administration of a nutritional formula that is enriched in pre-digested Triacylglyceride that do not require lipase action can significantly reduce the severity of NEC in a mouse model. We now hypothesise that this 'pre-digested fat (PDF) system' may reduce NEC-associated lung injury. In support of this hypothesis, we now show that rearing newborn mice on a nutritional formula based on the 'PDF system' promotes lung development, as evidenced by increased tight junctions and surfactant protein expression. Mice that were administered this 'PDF system' were significantly less vulnerable to the development of NEC-induced lung inflammation, and the administration of the 'PDF system' conferred lung protection. In seeking to define the mechanisms involved, the administration of the 'PDF system' significantly enhanced lung maturation and reduced the production of reactive oxygen species (ROS). These findings suggest that the PDF system protects the development of NEC-induced lung injury through effects on lung maturation and reduced ROS in the lung and also increases lung maturation in non-NEC mice.

The administration of amnion-derived multipotent cell secretome ST266 protects against necrotizing enterocolitis in mice and piglets

Necrotizing enterocolitis (NEC) is the leading cause of death from gastrointestinal disease in premature infants and is steadily rising in frequency. Patients who develop NEC have a very high mortality, illustrating the importance of developing novel prevention or treatment approaches. We and others have shown that NEC arises in part from exaggerated signaling via the bacterial receptor, Toll-like receptor 4 (TLR4) on the intestinal epithelium, leading to widespread intestinal inflammation and intestinal ischemia. Strategies that limit the extent of TLR4 signaling, including the administration of amniotic fluid, can reduce NEC development in mouse and piglet models. We now seek to test the hypothesis that a secretome derived from amnion-derived cells can prevent or treat NEC in preclinical models of this disease via a process involving TLR4 inhibition. In support of this hypothesis, we show that the administration of this secretome, named ST266, to mice or piglets can prevent and treat experimental NEC. The protective effects of ST266 occurred in the presence of marked TLR4 inhibition in the intestinal epithelium of cultured epithelial cells, intestinal organoids, and human intestinal samples ex vivo, independent of epidermal growth factor. Strikingly, RNA-seq analysis of the intestinal epithelium in mice reveals that the ST266 upregulates critical genes associated with gut remodeling, intestinal immunity, gut differentiation. and energy metabolism. These findings show that the amnion-derived secretome ST266 can prevent and treat NEC, suggesting the possibility of novel therapeutic approaches for patients with this devastating disease.NEW & NOTEWORTHY This work provides hope for children who develop NEC, a devastating disease of premature infants that is often fatal, by revealing that the secreted product of amniotic progenitor cells (called ST266) can prevent or treat NEC in mice, piglet, and "NEC-in-a-dish" models of this disease. Mechanistically, ST266 prevented bacterial signaling, and a detailed transcriptomic analysis revealed effects on gut differentiation, immunity, and metabolism. Thus, an amniotic secretome may offer novel approaches for NEC.

Infection prevention for extremely low birth weight infants in the NICU

Extremely preterm infants are particularly vulnerable to systemic infections secondary to their immature immune defenses, prolonged hospitalizations, delays in enteral feeding, early antibiotic exposure, and need for life-sustaining invasive interventions. There have been several evidence-based practices for infection prevention in this population, such as human milk feedings, utilization of "bundle checklists" and decolonization of pathogenic organisms. Other practices, such as the use of probiotics, human milk-derived fortifiers, and antifungal prophylaxis are more controversial and require further investigation regarding the risks and benefits of such interventions. This chapter examines the susceptibility of the preterm newborn infant to invasive infections and describes several strategies for infection prevention, along with the associated limitations of such practices. It also addresses the various gaps in our understanding of preventing infections in this population, and the need for additional large multi-center randomized controlled trials. Additionally, the role of the SARs-CoV-2 global pandemic and associated strategies for infection prevention in the NICU are discussed.