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

Digging deeper into necrotizing enterocolitis: bridging clinical, microbial, and molecular perspectives

Necrotizing Enterocolitis (NEC) is a severe, life-threatening inflammatory condition of the gastrointestinal tract, especially affecting preterm infants. This review consolidates evidence from various biomedical disciplines to elucidate the complex pathogenesis of NEC, integrating insights from clinical, microbial, and molecular perspectives. It emphasizes the modulation of NEC-associated inflammatory pathways by probiotics and novel biologics, highlighting their therapeutic potential. We further critically examine dysbiotic alterations within the gut microbiota, with a particular focus on imbalances in bacterial and viral communities, which may contribute to the onset of NEC. The intricate interactions among toll-like receptor 4 (TLR4), microvascular integrity, immune activation, and the inflammatory milieu are meticulously summarized, offering a sophisticated understanding of NEC pathophysiology. This academic review aims to enhance the etiological comprehension of NEC, promote the development of targeted therapeutic interventions, and impart the significant impact of perinatal factors on the formulation of preventive and curative strategies for the disease.

Spatial transcriptomics delineates potential differences in intestinal phenotypes of cardiac and classical necrotizing enterocolitis

Necrotizing enterocolitis (NEC) is a devastating neonatal gastrointestinal disease, often resulting in multi-organ failure and death. While classical NEC is strictly associated with prematurity, cardiac NEC is a subset of the disease occurring in infants with comorbid congenital heart disease. Despite similar symptomatology, the NEC subtypes vary slightly in presentation and may represent etiologically distinct diseases. We compared ileal spatial transcriptomes of patients with cardiac and classical NEC. Epithelial and immune cells cluster well by cell-type segment and NEC subtype. Differences in metabolism and immune cell activation functionally differentiate the cell-type makeup of the NEC subtypes. The classical NEC phenotype is defined by dysbiosis-induced inflammatory signaling and metabolic acidosis, while that of cardiac NEC involves reduced angiogenesis and endoplasmic reticulum stress-induced apoptosis. Despite subtype-associated clinical and demographic variability, spatial transcriptomics has substantiated pathway and network differences within immune and epithelial segments between cardiac and classical NEC.

Clinical characterization of necrotizing enterocolitis in neonates with or without congenital heart disease: a case-control study

BACKGROUND

This study aimed to analyze the clinical characteristics and differences between neonates with congenital heart disease (CHD)-related neonatal necrotizing enterocolitis (NEC) and those with non-CHD-related neonatal NEC.

METHOD

This retrospective study included patients with CHD who met Bell's staging diagnostic criteria and were hospitalized between 2014 and 2023 in the Cardiac Intensive Care Unit of Cardiothoracic Surgery, Shanghai Children's Medical Center affiliated to Shanghai Jiao Tong University School of Medicine. These patients comprised the CHD-related NEC group (CHD-NEC group). Meanwhile, the control group included randomly matched non-CHD-related NEC children (nCHD-NEC group) admitted to the neonatal department of the Second People's Hospital in Kashi Prefecture according to the 1:2 matching principle. Patients' basic information, adverse clinical events before NEC onset as well as NEC severity and treatment were recorded.

RESULTS

The CHD-NEC group comprised 60 cases, whereas the nCHD-NEC group comprised 120 cases. Compared with the nCHD-NEC group, the CHD-NEC group had an older gestational age (38.71 [37.89, 39.67] weeks vs. 30.65 [29.68, 32.29] weeks, p < 0.001); a heavier birth weight (3.2 [2.69, 3.67] kg vs. 1.39 [1.1, 1.59] kg, p < 0.001); and higher proportions of patent ductus arteriosus (73.3% vs. 26.7%, p < 0.001), shock (81.7% vs. 36.7%, p < 0.001), and mechanical ventilation requirement (91.7% vs. 51.7%, p < 0.001). At disease onset, the CHD-NEC group had a higher vasoactive drug score (16.75 [7.26, 23.63] vs. 0 [0, 10], p < 0.001) but lower values for the proportion of infants who were small for gestational age (15% vs. 33.3%, p = 0.045), incidence of premature rupture of membranes (3.3% vs. 26.7%, p = 0.002), incidence of early onset sepsis (6.7% vs. 23.3%, p = 0.038), and incidence of late onset sepsis (46.7% vs. 70%, p = 0.036) than the nCHD-NEC group. Among children who required abdominal surgery, the CHD-NEC group tended to have more colon involvement (6.6% vs. 0.8%, p = 0.063), but no significant difference in mortality was noted between the two groups.

CONCLUSION

Children with CHD-NEC and nCHD-NEC have significantly different clinical characteristics. CHD-NEC is mainly observed in full-term infants with appropriate weight for gestational age, and perioperative intestinal ischemia may be the main pathophysiology. Conversely, nCHD-NEC is mainly noted in preterm infants, possibly related to immature intestinal development and infection. Large prospective clinical research is warranted to explore the pathogenesis, pathophysiology, indicator monitoring, and treatment plan for children with NEC.

Role of gut microbiome in developing necrotizing enterocolitis

Necrotizing enterocolitis (NEC) is one of the most devastating intestinal diseases observed in preterm in the first days of life. Researchers have recently focused on potential predictive biomarkers for early and concomitant diagnoses. Thus, we inquired about the linkage of intestinal dysbiosis, one of the most important factors in NEC development to the gut microbiota. In this study, the systematic differences in the bacterial composition between neonates affected by NEC and healthy newborns were highlighted by metagenomic analysis. The next-generation sequencing of the V3-V4 variable region of the 16S rRNA gene and gene-specific qPCR analyzed the untargeted gut microbiota. Total bacteria, total and fecal coliform loads in stool samples with NEC were higher than control. OTU-level relative abundances of NEC infant was characterized by Firmicutes and Bacteroidetes at phylum levels. At the genus level, NEC stool was identified by the lack of Klebsiella and the presence of Roseburia, Blautia, and Parasutterella. Finally, Clostridium fessum was the predominant species of Clostridium genus in disease and healthy specimens at the species level, whereas Clostridium jeddahitimonense was at NEC diagnosis. Despite a strong relationship between pathophysiology and characterization of gut microbiota at a clinical diagnosis of NEC, our results emphasize the broad difficulty in identifying potential biomarkers.

Zearalenone enhances TSST-1 production by intestinal Staphylococcus and increases uterine immune stress in rats

Zearalenone (ZEA), a mycotoxin prevalent in food crops, poses significant health risks, particularly through its impact on the gut-uterus axis. This study assessed the effects of a 5 mg/kg body weight ZEA dosage in female SD rats, focusing on gut microbiota alterations, inflammatory responses, and uterine changes. Our findings revealed substantial shifts in microbial composition, including significant reductions in beneficial genera such as Akkermansia and Ruminococcaceae and marked increases in pathogenic staphylococci, which correlated with elevated levels of toxic shock syndrome toxin-1 (TSST-1) in serum and uterine tissue. RNA sequencing of uterine samples indicated activation of the extracellular matrix (ECM) pathway, along with significant upregulation of MMP-2 and TIMP-2, enzymes associated with ECM remodelling. Correlation analysis showed a strong link between staphylococcal proliferation and ECM pathway activation, suggesting that ZEA-induced gut dysbiosis contributes to uterine inflammation and structural alterations. These results reveal how ZEA disrupts gut and uterine health, highlighting critical pathways that could serve as targets for future preventive and therapeutic strategies against mycotoxin exposure.

Effect of gestational age on clinical features in necrotizing enterocolitis-associated intestinal perforation

Purpose

To investigate the clinical features of necrotizing enterocolitis-associated intestinal perforation (NEC-IP) in neonates with different gestational ages (GAs). Furthermore, we also want to identify the risk factors of poor prognosis for these patients.

Methods

The retrospective study of patients with NEC-IP was conducted with basic information, comorbidity, intraoperative findings, related treatment, and prognosis. According to the GA, patients were divided into three groups: early (GA: 28-<32 weeks, Group 1), mid-term (GA: 32-<34 weeks, Group 2), and late (GA: 34-<37 weeks, Group 3). The clinical features of the three groups were analyzed, and risk factors for poor prognosis were identified.

Results

Of the 113 cases, the number of cases in Groups 1 to 3 was 36 (31.9%), 44 (38.9%), and 33 (29.2%), respectively; and the overall proportion of poor prognosis was 19.4% (22/113). For basic information, the birth weight of Group 1 was lower than that of Group 2 and Group 3, while the postnatal day at the time of surgery of NEC and the onset age were higher than that of Group 2 (onset age: G1 12.0[7.00;20.5], G2 9.00[4.00;13.0]; postnatal day at the time of surgery: G1 22.0[13.8;27.2], G2 13.0[8.00;21.0]) (P < 0.016). For comorbidity, the incidence of sepsis, coagulopathy, type of (congenital heart disease) CHD, and hypoproteinemia in Group 1 was higher than that in Group 2 (all P < 0.016), and the incidence of respiratory failure, hypoproteinemia in Group 1 was higher than that in Group 3 (all P < 0.016). For related treatment, the usage rate of vasoactive substances and mechanical ventilation in Group 1 was higher than that of Group 2 and Group 3 (all P < 0.016). By Lasso and Logistic regression analysis, we found that GA (OR: 0.274, 95%CI: 0.078-0.796), sepsis (OR: 7.955, 95%CI: 1.424-65.21), coagulopathy (OR: 19.51, 95%CI: 3.393-179.1), CHD (OR: 6.99, 95%CI: 1.418-54.83) and diseased bowel segment (OR: 2.804, 95%CI: 1.301-7.316) were the independent factors for poor prognosis (all P < 0.05).

Conclusions

The clinical features of NEC-IP patients differ based on GA, particularly in terms of CHD type, postnatal day at the time of surgery, utilization of vasoactive substances, and prognosis. Furthermore, GA, sepsis, coagulopathy, CHD, and diseased bowel segment are independent factors for poor prognosis of patients with NEC-IP.

Necrotizing Enterocolitis: Pathogenetic Features and Differential Diagnosis with Inflammatory Bowel Disease in Newborns

Necrotizing enterocolitis (NEC) is a disease primarily affecting premature infants. NEC pathogenesis is based on the development of inflammation damaging mucous membranes associated with bacterial colonization, intestinal epithelium immaturity, intestinal blood flow regulation, and excessive inflammatory response activation. Inflammatory bowel disease (IBD) with very early onset (VEO-IBD) can also manifest in the neonatal period. They are characterized by severe course, often resistant to traditional immunosuppressive therapy. This article discusses the features of NEC pathogenesis and differential diagnosis with VEO-IBD. Despite certain similarities in pathogenesis, NEC and IBD are different diseases. Infantile onset IBD is more often associated with monogenic diseases and primary immunodeficiency. VEO-IBD is a chronic disease characterized by damage to all intestinal layers and has a lower incidence compared to NEC. Its clinical manifestations may include chronic diarrhea, blood in stool, delayed physical development, perianal diseases, and ulcerations in the oral cavity. Infantile onset VEO-IBD usually affects the colon, while NEC affects the ileum in premature infants. The intestinal microbiome in VEO-IBD also has specific features. It has been reported that clinical cases of Crohn’s disease in patients who had NEC in the neonatal period are associated with NEC surgery. It is crucial to consider perinatal period features when assessing the IBD risk (prenatal effects of antibacterial therapy and smoking, several courses of antibacterial therapy during the first year of life, and formula feeding).

CCL3 as a novel biomarker in the diagnosis of necrotizing enterocolitis

OBJECTIVES

Neonatal necrotizing enterocolitis (NEC) is a common intestinal disease that threatens the lives of newborns and is characterized by ischemic necrosis of the small intestine and colon. As early diagnosis of NEC improves prognosis, the identification of new or complementary biomarkers is of great importance. In this study, we evaluate the diagnostic value of CCL3 in NEC and compare its effectiveness with other commonly used biomarkers, such as procalcitonin (PCT) and C-reactive protein (CRP).

PARTICIPANTS AND DESIGN

Serum samples were collected from 64 patients with NEC and 38 jaundice neonatal controls. Before initiating therapy, blood samples for the whole blood count, CRP, PCT and CCL3 were obtained from all neonates. Receiver operating characteristic (ROC) curve and multivariate logistic regression analyses were performed.

SETTING

Department of Clinical Laboratory, Children's Hospital of Chongqing Medical University.

RESULTS

The serum CCL3 level of the NEC group was significantly higher than that of the Control group. The ROC area under the curve (AUC) was 0.8614 (95%confidence interval (CI) 0.7863-0.936; p < 0.0001) for CCL3, 0.8534 (95% CI 0.7682-0.9386; p < 0.0001) for PCT, 0.675 (95% CI 0.5625-0.788; p < 0.0001) for CRP, 0.579 (95% CI 0.4402-0.7188 p = 0.2460) for WBC, and 0.7384 (95% CI 0.6215-0.8554 p = 0.0005) for PLT. With a cut-off value of 83.33 ng/ml, the diagnostic sensitivity and negative predictive value of CCL3 were 83.33% and 80.55%, respectively. The combined use of CCL3 and PCT could significantly improve diagnostic performance for NEC (0.903; 95% CI 0.810-0.960; p < 0.0001).

CONCLUSIONS

CCL3 may be used as a promising biomarker for the diagnosis of NEC, and the combined use of CCL3 and PCT could improve the diagnosis of NEC.

Comparison of Gut Microbiomes Between Neonates Born by Cesarean Section and Vaginal Delivery: Prospective Observational Study

Background: Balanced diversity and abundance of gut microbiome play important roles in human health, including neonatal health. Though not established, there is evidence that the delivery route could alter the diversity of neonatal gut microbiomes. Objective: The objective of the study was to investigate the differences in the gut microbiomes of neonates delivered via cesarean section compared to those born by vaginal delivery and to identify the predominant microbial taxa present in each group. Study Design: A prospective observational study of 281 healthy neonates born between February 2021 and April 2023 at Her Royal Highness Maha Chakri Sirindhorn Medical Center, Srinakharinwirot University, Thailand, was performed. The study population was divided into two groups: 139 neonates born via vaginal delivery and 141 neonates born via cesarean section. The microbiota composition of each neonate's fecal sample was identified by using 16S ribosomal ribonucleic acid metagenomic sequencing. Results: Neonates delivered vaginally exhibited a gut microbiome with higher abundance and diversity than those delivered by cesarean delivery. Bifidobacterium was the dominant genus in both groups. Bifidobacterium breve was the dominant species and was significantly higher in cesarean-delivered neonates compared to those delivered vaginally (24.0% and 9.2%, respectively) (p < 0.001). However, the taxonomy of only 89 (64.0%) and 44 (31.43%) fecal samples could be identified from the vaginal and cesarean delivery groups, respectively. Conclusion: Route of delivery is associated with neonatal gut microbiome abundance and diversity. Neonates delivered via vaginal delivery exhibited higher diversity but lower abundance of the dominant species in the gut microbiome. Trial Registration: Thai Clinical Trials Registry identifier: TCTR20221024003.

Network-Based Bioinformatics Highlights Broad Importance of Human Milk Hyaluronan

Human milk (HM) is rich in bioactive factors promoting postnatal small intestinal development and maturation of the microbiome. HM is also protective against necrotizing enterocolitis (NEC), a devastating inflammatory condition predominantly affecting preterm infants. The HM glycosaminoglycan, hyaluronan (HA), is present at high levels in colostrum and early milk. Our group has demonstrated that HA with a molecular weight of 35 kDa (HA35) promotes maturation of the murine neonatal intestine and protects against two distinct models of NEC. However, the molecular mechanisms underpinning HA35-induced changes in the developing ileum are unclear. CD-1 mouse pups were treated with HA35 or vehicle control daily, from P7 to P14, and we used network and functional analyses of bulk RNA-seq ileal transcriptomes to further characterize molecular mechanisms through which HA35 likely influences intestinal maturation. HA35-treated pups separated well by principal component analysis, and cell deconvolution revealed increases in stromal, Paneth, and mature enterocyte and progenitor cells in HA35-treated pups. Gene set enrichment and pathway analyses demonstrated upregulation in key processes related to antioxidant and growth pathways, such as nuclear factor erythroid 2-related factor-mediated oxidative stress response, hypoxia inducible factor-1 alpha, mechanistic target of rapamycin, and downregulation of apoptotic signaling. Collectively, pro-growth and differentiation signals induced by HA35 may present novel mechanisms by which this HM bioactive factor may protect against NEC.

Human breast milk-derived phospholipid DOPE ameliorates intestinal injury associated with NEC by inhibiting ferroptosis

Neonatal necrotizing enterocolitis (NEC) is a severe inflammatory bowel disease that commonly affects premature infants. Breastfeeding has been proven to be one of the most effective methods for preventing NEC. However, the specific role of lipids, the second major nutrient category in human breast milk (HBM), in intestinal development remains unclear. Our preliminary lipidomic analysis of the HBM lipidome revealed that dioleoyl phosphatidylethanolamine (DOPE) is not only abundant but also shows high solubility in lipids, endowing it with significant biological utility. Experimental results confirmed that DOPE significantly reduces the mortality of neonatal rats, ameliorates impairment of intestinal barrier function, and alleviates the expression of intestinal inflammatory factors IL-1β and IL-6. Furthermore, DOPE promotes the migration and proliferation of intestinal epithelial cells, thereby enhancing the integrity of the intestinal barrier function in vitro. The progression of NEC is linked with the onset of ferroptosis. Our cellular-level analysis of lipid peroxide and iron ion concentrations revealed that DOPE significantly reduces the indicators of ferroptosis, while also modulating the expression of pivotal ferroptosis-associated factors, including SLC7A11, GPX4, and ACSL4. Hence, this research on DOPE is expected to provide novel insights into the bioactive lipids present in HBM.

Gut Microbiota-Derived Metabolites and Their Role in the Pathogenesis of Necrotizing Enterocolitis in Preterm Infants: A Narrative Review

Background: Necrotizing enterocolitis (NEC) is a severe gastrointestinal disease that occurs predominantly in premature infants and is characterized by the inflammation and necrosis of the intestine, showing high morbidity and mortality rates. Despite decades of research efforts, a specific treatment is currently lacking, and preventive strategies are the mainstays of care. This review aims to help understand the complex interplay between gut microbiota and their metabolites in NEC pathogenesis. In particular, we focused on how these factors can influence gut health, immune responses, and intestinal barrier integrity. Discussion: Current research has increasingly focused on the role of the gut microbiota and their metabolites in NEC pathogenesis, thanks to their involvement in modulating gut health, immune responses, and intestinal barrier integrity. Conclusions: A deeper understanding of the interplay between gut microbiota and their metabolites is essential for developing personalized strategies to prevent NEC. By targeting these microbial interactions, new therapeutic approaches may emerge that offer improved outcomes for preterm infants at a high risk of NEC.

Construction and evaluation of a risk model for adverse outcomes of necrotizing enterocolitis based on LASSO-Cox regression

Objective

This study aimed to develop a nomogram to predict adverse outcomes in neonates with necrotizing enterocolitis (NEC).

Methods

In this retrospective study on neonates with NEC, data on perinatal characteristics, clinical features, laboratory findings, and x-ray examinations were collected for the included patients. A risk model and its nomogram were developed using the least absolute shrinkage and selection operator (LASSO) Cox regression analyses.

Results

A total of 182 cases of NEC were included and divided into a training set (148 cases) and a temporal validation set (34 cases). Eight features, including weight [p = 0.471, HR = 0.99 (95% CI: 0.98-1.00)], history of congenital heart disease [p < 0.001, HR = 3.13 (95% CI:1.75-5.61)], blood transfusion before onset [p = 0.757, HR = 0.85 (95%CI:0.29-2.45)], antibiotic exposure before onset [p = 0.003, HR = 5.52 (95% CI:1.81-16.83)], C-reactive protein (CRP) at onset [p = 0.757, HR = 1.01 (95%CI:1.00-1.02)], plasma sodium at onset [p < 0.001, HR = 4.73 (95%CI:2.61-8.59)], dynamic abdominal x-ray score change [p = 0.001, HR = 4.90 (95%CI:2.69-8.93)], and antibiotic treatment regimen [p = 0.250, HR = 1.83 (0.65-5.15)], were ultimately selected for model building. The C-index for the predictive model was 0.850 (95% CI: 0.804-0.897) for the training set and 0.7880.788 (95% CI: 0.656-0.921) for the validation set. The area under the ROC curve (AUC) at 8-, 10-, and 12-days were 0.889 (95% CI: 0.822-0.956), 0.891 (95% CI: 0.829-0.953), and 0.893 (95% CI:0.832-0.954) in the training group, and 0.812 (95% CI: 0.633-0.991), 0.846 (95% CI: 0.695-0.998), and 0.798 (95%CI: 0.623-0.973) in the validation group, respectively. Calibration curves showed good concordance between the predicted and observed outcomes, and DCA demonstrated adequate clinical benefit.

Conclusions

The LASSO-Cox model effectively identifies NEC neonates at high risk of adverse outcomes across all time points. Notably, at earlier time points (such as the 8-day mark), the model also demonstrates strong predictive performance, facilitating the early prediction of adverse outcomes in infants with NEC. This early prediction can contribute to timely clinical decision-making and ultimately improve patient prognosis.

Global Insights and Key Trends in Gut Microbiota Research for Premature Infants: A Bibliometric and Visualization Study

Background

Premature infants, defined as those born before 37 weeks of gestation, face numerous health challenges due to their underdeveloped systems. One critical aspect of their health is the gut microbiota, which plays a vital role in their immune function and overall development. This study provides a comprehensive bibliometric analysis of research trends, influential contributors, and evolving themes in the study of gut microbiota in premature infants over the past two decades.

Methods

We conducted a bibliometric analysis using the Web of Science Core Collection database, covering publications from January 1, 2004, to June 17, 2024. We employed VOSviewer, the R package "bibliometrix", and Citespace for data visualization and analysis, focusing on co-authorship, co-citation, and keyword co-occurrence networks.

Results

The temporal analysis revealed a significant increase in research output on gut microbiota in premature infants, particularly in the last decade. Early research primarily focused on characterizing the gut microbiota of premature infants, identifying less diversity and a higher prevalence of pathogenic bacteria compared to full-term infants. Key research themes identified include probiotics, necrotizing enterocolitis (NEC), and breastfeeding. Probiotic studies highlighted the potential of strains like Bifidobacterium and Lactobacillus in reducing NEC and sepsis incidences. Breastfeeding research consistently showed the benefits of human milk in fostering a healthier gut microbiota profile. Co-authorship and co-citation analyses identified key contributors and influential studies, emphasizing strong international collaborations, particularly among researchers from the United States, China, and European countries.

Conclusion

This bibliometric analysis underscores the growing recognition of the gut microbiota's crucial role in the health of premature infants. The field has seen significant advancements, particularly in understanding how interventions like probiotics and breastfeeding can modulate gut microbiota to improve health outcomes. Continued research and international collaboration are essential to further unravel the complexities of gut microbiota in premature infants and develop effective therapeutic strategies.

Feeding cessation and antibiotics improve clinical symptoms and alleviate gut and systemic inflammation in preterm pigs sensitive to necrotizing enterocolitis

Necrotizing enterocolitis (NEC) is a microbiota- and feeding-related gut inflammatory disease in preterm infants. The standard of care (SOC) treatment for suspected NEC is antibiotic treatment and reduced enteral feeding, but how SOC treatment mitigates NEC remains unclear. We explored whether SOC treatment alone or combined with an anti-inflammatory protein (inter-alpha inhibitor protein, IAIP) supplementation improves outcomes in a preterm piglet model of formula-induced NEC. Seventy-one cesarean-delivered preterm piglets were initially fed formula, developing NEC symptoms by day 3, and then randomized into CON (continued feeding) or SOC groups (feeding cessation and antibiotics), each with or without human IAIP (2×2 factorial design). By day 5, IAIP treatment did not significantly influence outcomes, whereas SOC treatment effectively reduced NEC lesions, diarrhea, and bloody stools. Notably, SOC treatment improved gut morphology and function, dampened gut inflammatory responses, altered the colonic microbiota composition, and modulated systemic immune responses. Plasma proteomic analysis revealed the effects of SOC treatment on organ development and systemic inflammatory responses. Collectively, these findings suggest that SOC treatment significantly prevents NEC progression in preterm piglets via effects on gut structure, function, and microbiota, as well as systemic immune and inflammatory responses. Timely feeding cessation and antibiotics are critical factors in preventing NEC progression in preterm infants, while the benefits of additional human IAIP treatment remain to be established.

Gut microbiome and inflammation in response to increasing intermittent hypoxia in the neonatal rat

BACKGROUND

Intermittent hypoxia (IH) and oxidative stress play key roles in gut dysbiosis and inflammation. We tested the hypothesis that increasing numbers of daily IH episodes cause microbiome dysbiosis and severe gut injury.

METHODS

Neonatal rats were exposed to hyperoxia (Hx), growth restriction, and IH. For IH, pups were exposed to 2-12 daily episodes from birth (P0) to postnatal day 7 (7D) or P0-P14 (14D), with or without recovery in room air (RA) until P21. Animals raised in RA from P0 to P21 served as normoxia controls. Stool was expressed from the large intestines for microbiome analysis, and tissue samples were assessed for histopathology and biomarkers of inflammation.

RESULTS

Hx and IH caused a significant reduction in the number and diversity of organisms. The severity of gut injury and levels of inflammatory cytokines and TLR4 increased, while total glutathione (tGSH) declined, with increasing daily IH episodes. The number of organisms correlated with the villi number (p < 0.05) and tGSH depletion (p < 0.001).

CONCLUSIONS

The critical number of daily IH episodes that the newborn gut may sustain is 6, beyond which irreversible damage occurs. The immature gut is highly susceptible to IH-induced injury, and IH may contribute to pathological outcomes in the immature gut.

IMPACT STATEMENT

1. The neonatal gut at birth is highly susceptible to intermittent hypoxia (IH) injury. 2. IH causes gut dysbiosis, inflammation, and glutathione depletion. 3. The severity of gut injury worsens as a function of increasing daily IH episodes. 4. The critical number of daily IH episodes that the newborn gut may sustain is 6, beyond which irreversible damage occurs.

PhoP/PhoQ Two-Component System Contributes to Intestinal Inflammation Induced by Cronobacter sakazakii in Neonatal Mice

Cronobacter sakazakii (C. sakazakii) is a foodborne pathogen capable of causing severe infections in newborns. The PhoP/PhoQ two-component system exerts a significant influence on bacterial virulence. This study aimed to investigate the impact of the PhoP/PhoQ system on intestinal inflammation in neonatal mice induced by C. sakazakii. Neonatal mice were infected orally by C. sakazakii BAA-894 (WT), a phoPQ-gene-deletion strain (ΔphoPQ), and a complementation strain (ΔphoPQC), and the intestinal inflammation in the mice was monitored. Deletion of the phoPQ gene reduced the viable count of C. sakazakii in the ileum and alleviated intestinal tissue damage. Moreover, caspase-3 activity in the ileum of the WT- and ΔphoPQC-infected mice was significantly elevated compared to that of the ΔphoPQ and control groups. ELISA results showed elevated levels of TNF-α and IL-6 in the ileum of the mice infected with WT and ΔphoPQC. In addition, deletion of the phoPQ gene in C. sakazakii resulted in a down-regulation of inflammatory genes (IL-1β, TNF-α, IL-6, NF-κB p65, TLR4) within the ileum and decreased inflammation by modulating the TLR4/NF-κB pathway. It is suggested that targeting the PhoP/PhoQ two-component system could be a potential strategy for mitigating C. sakazakii-induced neonatal infections.

Rapidly progressive necrotizing enterocolitis: Risk factors and a predictive model

BACKGROUND

Rapidly progressive necrotizing enterocolitis (RP-NEC) is a particular subtype of NEC known for its rapid progression and high mortality rate. The objective of this study was to establish a predictive model for RP-NEC.

METHODS

This was a retrospective single-center cohort study. Patients were newborn infants with NEC (Bell's stage ≥ IIB) admitted from January 1, 2016 to December 31, 2023. The primary outcome was RP-NEC defined as the need for surgical intervention and/or death within 48 hours of the onset of NEC.

RESULTS

Totally 334 newborn infants were included, among which 82 (24.6%) were RP-NEC cases with a gestation age 34.1 (31.0, 37.0) weeks and birth weight 2100 (1413, 2800) g. Plasma sodium <135 mmol/L, C-reactive protein ≥10 mg/L, platelet count <100 × 109/L, lymphocyte count <1.5 × 109/L, pH <7.2 in blood gas, and ascites at NEC onset were identified as independent risk factors for RP-NEC. The model established presented an AUC value of 0.983 (95% CI 0.97-0.99). The calibration curve for validation was applied revealing a slope close to unity while the Hosmer-Lemeshow test yielded χ2 = 2.550 (p = 0.636).

CONCLUSION

The predictive model established on the above 6 items of RP-NEC is highly promising.

IMPACT

Currently, there is a paucity of research on this specific type of severe necrotizing enterocolitis (NEC) characterized by rapid progression. Our study was to investigate the risk factors associated with surgical intervention and/or death within 48 hours following onset in infants with NEC, establish a predictive model for infants with rapidly progressive NEC. The new data presented in this study was the ROC curve combining the above factors as well as hyponatremia.

Modern View on Very Early Onset and Early Onset Inflammatory Bowel Diseases in Children

Nowadays, an urgent problem of pediatric gastroenterology is the study of inflammatory bowel diseases with very early onset (VEO-IBD), which have unique genetic, clinical, immunological, morphological, and laboratory sings. Early VEO-IBD is usually considered as monogenic disease, especially in combination with congenital immune defects, which leads to difficulties in diagnosis and management this pathology. Despite this, systematization of information about this group of nosological forms of IBD is practically not carried out. This article presents a review of the available information on etiological factors, course variants, and therapeutic options for VEO-IBD.

I-FABP protein/mRNA and IL-6 as biomarkers of intestinal barrier dysfunction in neonates with necrotizing enterocolitis and SPF BALB/c mouse models

OBJECTIVE

Neonatal necrotizing enterocolitis (NEC) is a serious intestinal inflammatory disease. We investigated intestinal fatty acid binding protein (I-FABP), I-FABP mRNA, and interleukin-6 (IL-6) as potential diagnostic biomarkers in NEC.

METHODS

Forty mice were subjected to hypoxic-ischemic intestinal injury, and then serum I-FABP protein and mRNA levels were quantified. Ileal tissue pathological scores were determined by hematoxylin and eosin staining. I-FABP expression levels and translocation in these tissues were detected using western blotting and immunofluorescence, respectively. Samples from 30 human neonates with NEC and 30 healthy neonates had serum I-FABP protein/mRNA and IL-6 levels measured.

RESULTS

The mouse ileal tissue pathological score and I-FABP levels, as well as serum I-FABP and I-FABP mRNA levels, were significantly higher in the model group than in the control group. Serum I-FABP, I-FABP mRNA, and IL-6 levels were significantly higher in human neonates with NEC than in the healthy group. Logistic regression and receiver operating curve analyses revealed that I-FABP protein/mRNA and IL-6 levels could be diagnostic biomarkers for NEC.

CONCLUSIONS

I-FABP protein/mRNA and IL-6 levels are useful biomarkers of intestinal ischemic injury in neonates with NEC. The combined detection of I-FABP protein/mRNA and IL-6 is recommended rather than using a single biomarker.

Gut Microbiota and Immune System in Necrotizing Enterocolitis and Related Sepsis

A severe condition of sepsis can be a complication of necrotizing enterocolitis (NEC), which can occur in premature infants and becomes a medical challenge in the neonatal intensive care unit (NICU). It is a multifactorial intestinal disease (can affect both the small and large intestine) that can lead to ischemia of the intestinal tissues that evolves into acute organ necrosis. One of these factors is that different types of nutrition can influence the onset or the progression of the disease. Cow-milk-based infant formulas have been shown to cause it in premature infants more frequently than human milk. Recently, nutrition has been shown to be beneficial after surgery. Several issues still under study, such as the pathogenesis and the insufficient and often difficult therapeutic approach, as well as the lack of a common and effective prevention strategy, make this disease an enigma in daily clinical practice. Recent studies outlined the emerging role of the host immune system and resident gut microbiota, showing their close connection in NEC pathophysiology. In its initial stages, broad-spectrum antibiotics, bowel rest, and breastfeeding are currently used, as well as probiotics to help the development of the intestinal microbiota and its eubiosis. This paper aims to present the current knowledge and potential fields of research in NEC pathophysiology and therapeutic assessment.

Photoacoustic Imaging as a Novel Non-invasive Biomarker to Assess Intestinal Tissue Oxygenation and Motility in Neonatal Rats

BACKGROUND

Within the premature infant intestine, oxygenation and motility play key physiological roles in healthy development and disease such as necrotizing enterocolitis. To date, there are limited techniques to reliably assess these physiological functions that are also clinically feasible for critically ill infants. To address this clinical need, we hypothesized that photoacoustic imaging (PAI) can provide non-invasive assessment of intestinal tissue oxygenation and motility to characterize intestinal physiology and health.

METHODS

Ultrasound and photoacoustic images were acquired in 2-day and 4-day old neonatal rats. For PAI assessment of intestinal tissue oxygenation, an inspired gas challenge was performed using hypoxic, normoxic, and hyperoxic inspired oxygen (FiO2). For intestinal motility, oral administration of ICG contrast agent was used to compare control animals to an experimental model of loperamide-induced intestinal motility inhibition.

RESULTS

PAI demonstrated progressive increases in oxygen saturation (sO2) as FiO2 increased, while the pattern of oxygen localization remained relatively consistent in both 2-day and 4-day old neonatal rats. Analysis of intraluminal ICG contrast enhanced PAI images yielded a map of the motility index in control and loperamide treated rats. From PAI analysis, loperamide significantly inhibited intestinal motility, with a 32.6% decrease in intestinal motility index scores in 4-day old rats.

CONCLUSION

These data establish the feasibility and application of PAI to non-invasively and quantitatively measure intestinal tissue oxygenation and motility. This proof-of-concept study is an important first step in developing and optimizing photoacoustic imaging to provide valuable insight into intestinal health and disease to improve the care of premature infants.

The Effect of Oral Iron Supplementation/Fortification on the Gut Microbiota in Infancy: A Systematic Review and Meta-Analysis

(1) Background: Iron is an essential metal for the proper growth and neurodevelopment of infants. To prevent and treat iron deficiency, iron supplementation or fortification is often required. It has been shown, though, that it affects the synthesis of gut microbiota. (2) Methods: This paper is a systematic review and meta-analysis of the effect of oral iron supplementation/fortification on the gut microbiota in infancy. Studies in healthy neonates and infants who received per os iron with existing data on gut microbiota were included. Three databases were searched: PUBMED, Scopus, and Google Scholar. Randomized controlled trials (RCTs) were included. Quality appraisal was assessed using the ROB2Tool. (3) Results: A total of six RCTs met inclusion criteria for a systematic review, and four of them were included in the meta-analysis using both the fixed and random effects methods. Our results showed that there is very good heterogeneity in the iron group (I2 = 62%), and excellent heterogeneity in the non-iron group (I2 = 98%). According to the meta-analysis outcomes, there is a 10.3% (95% CI: -15.0--5.55%) reduction in the bifidobacteria population in the iron group and a -2.96% reduction for the non-iron group. There is a confirmed difference (p = 0.02) in the aggregated outcomes between iron and non-iron supplement, indicative that the bifidobacteria population is reduced when iron supplementation is given (total reduction 6.37%, 95%CI: 10.16-25.8%). (4) Conclusions: The abundance of bifidobacteria decreases when iron supplementation or fortification is given to infants.

Gut microbiome derived short chain fatty acids: Promising strategies in necrotising enterocolitis

Necrotising enterocolitis (NEC) is a devastating condition that poses a significant risk of morbidity and mortality, particularly among preterm babies. Extensive research efforts have been directed at identifying optimal treatment and diagnostic strategies but results from such studies remain unclear and controversial. Among the most promising candidates are prebiotics, probiotics and their metabolites, including short chain fatty acids (SCFAs). Such metabolites have been widely explored as possible biomarkers of gut health for different clinical conditions, with overall positive effects on the host observed. This review aims to describe the role of gut microbiome derived SCFAs in necrotising enterocolitis. Until now, information has been conflicting, with the primary focus on the main three SCFAs (acetic acid, propionic acid, and butyric acid). While numerous studies have indicated the relationship between SCFAs and NEC, the current evidence is insufficient to draw definitive conclusions about the use of these metabolites as NEC biomarkers or their potential in treatment strategies. Ongoing research in this area will help enhance both our understanding of SCFAs as valuable indicators of NEC and their practical application in clinical settings.

Probiotic-Derived Ecto-5'-Nucleotidase Produces Anti-Inflammatory Adenosine Metabolites in Treg-Deficient Scurfy Mice

Probiotic Limosilactobacillus reuteri DSM 17938 (DSM 17938) prolongs the survival of Treg-deficient scurfy (SF) mice and reduces multiorgan inflammation by a process requiring adenosine receptor 2A (A2A) on T cells. We hypothesized that L. reuteri-derived ecto-5'-nucleotidase (ecto-5'NT) activity acts to generate adenosine, which may be a central mediator for L. reuteri protection in SF mice. We evaluated DSM 17938-5'NT activity and the associated adenosine and inosine levels in plasma, gut, and liver of SF mice. We examined orally fed DSM 17938, DSM 17938Δ5NT (with a deleted 5'NT gene), and DSM 32846 (BG-R46) (a naturally selected strain derived from DSM 17938). Results showed that DSM 17938 and BG-R46 produced adenosine while "exhausting" AMP, whereas DSM 17938∆5NT did not generate adenosine in culture. Plasma 5'NT activity was increased by DSM 17938 or BG-R46, but not by DSM 17938Δ5NT in SF mice. BG-R46 increased both adenosine and inosine levels in the cecum of SF mice. DSM 17938 increased adenosine levels, whereas BG-R46 increased inosine levels in the liver. DSM 17938Δ5NT did not significantly change the levels of adenosine or inosine in the GI tract or the liver of SF mice. Although regulatory CD73+CD8+ T cells were decreased in spleen and blood of SF mice, these regulatory T cells could be increased by orally feeding DSM 17938 or BG-R46, but not DSM 17938Δ5NT. In conclusion, probiotic-5'NT may be a central mediator of DSM 17938 protection against autoimmunity. Optimal 5'NT activity from various probiotic strains could be beneficial in treating Treg-associated immune disorders in humans.

Photoacoustic Imaging as a Novel Non-Invasive Biomarker to Assess Intestinal Tissue Oxygenation and Motility in Neonatal Rats

Background

Within the premature infant intestine, oxygenation and motility play key physiological roles in healthy development and disease such as necrotizing enterocolitis. To date, there are limited techniques to reliably assess these physiological functions that are also clinically feasible for critically ill infants. To address this clinical need, we hypothesized that photoacoustic imaging (PAI) can provide non-invasive assessment of intestinal tissue oxygenation and motility to characterize intestinal physiology and health.

Methods

Ultrasound and photoacoustic images were acquired in 2-day and 4-day old neonatal rats. For PAI assessment of intestinal tissue oxygenation, an inspired gas challenge was performed using hypoxic, normoxic, and hyperoxic inspired oxygen (FiO2). For intestinal motility, oral administration of ICG contrast agent was used to compare control animals to an experimental model of loperamide-induced intestinal motility inhibition.

Results

PAI demonstrated progressive increases in oxygen saturation (sO2) as FiO2 increased, while the pattern of oxygen localization remained relatively consistent in both 2-day and 4-day old neonatal rats. Analysis of intraluminal ICG contrast enhanced PAI images yielded a map of the motility index in control and loperamide treated rats. From PAI analysis, loperamide significantly inhibited intestinal motility, with a 32.6% decrease in intestinal motility index scores in 4-day old rats.

Conclusion

These data establish the feasibility and application of PAI to non-invasively and quantitatively measure intestinal tissue oxygenation and motility. This proof-of-concept study is an important first step in developing and optimizing photoacoustic imaging to provide valuable insight into intestinal health and disease to improve the care of premature infants.

Highlights

Intestinal tissue oxygenation and intestinal motility are important biomarkers of intestinal physiology in health and disease of premature infants.This proof-of-concept preclinical rat study is the first to report application of photoacoustic imaging for the neonatal intestine.Photoacoustic imaging is demonstrated as a promising non-invasive diagnostic imaging method for quantifying intestinal tissue oxygenation and intestinal motility in premature infants.

Graphical abstract

Probiotic-derived ecto-5'-nucleotidase produces anti-inflammatory adenosine metabolites in Treg-deficient scurfy mice

Probiotic Limosilactobacillus reuteri DSM 17938 (DSM 17938) prolonges the survival of Treg-deficient scurfy (SF) mice and reduces multiorgan inflammation by a process requiring adenosine receptor 2A (A _2A ) on T cells. We hypothesized that L. reuteri -derived ecto-5'-nucleotidase (ecto-5'NT) activity acts to generate adenosine, which may be a central mediator for L. reuteri protection in SF mice. We evaluated DSM 17938-5'NT activity and the associated adenosine and inosine levels in plasma, gut and liver of SF mice. We examined orally fed DSM 17938, DSM 17938Δ5NT (with a deleted 5'NT gene), and DSM 32846 (BG-R46) (a naturally selected strain derived from DSM 17938). Results showed that DSM 17938 and BG-R46 produced adenosine while "exhausting" AMP, whereas DSM 17938∆5NT did not generate adenosine in culture. Plasma 5'NT activity was increased by DSM 17938 or BG-R46, but not by DSM 17938Δ5NT in SF mice. BG-R46 increased both adenosine and inosine levels in the cecum of SF mice. DSM 17938 increased adenosine levels, whereas BG-R46 increased inosine levels in the liver. DSM 17938Δ5NT did not significantly change the levels of adenosine or inosine in the GI tract or the liver of SF mice. Although regulatory CD73 ⁺ CD8 ⁺ T cells were decreased in spleen and blood of SF mice, these regulatory T cells could be increased by orally feeding DSM 17938 or BG-R46, but not DSM 17938Δ5NT. In conclusion, probiotic-5'NT may be a central mediator of DSM 17938 protection against autoimmunity. Optimal 5'NT activity from various probiotic strains could be beneficial in treating Treg-associated immune disorders in humans.