Necrotizing enterocolitis: old problem with new hope

Bench to bedside - new insights into the pathogenesis of necrotizing enterocolitis

Necrotizing enterocolitis (NEC) is the leading cause of death and disability from gastrointestinal disease in premature infants. Recent discoveries have shed light on a unifying theorem to explain the pathogenesis of NEC, suggesting that specific treatments might finally be forthcoming. A variety of experiments have highlighted how the interaction between bacterial signalling receptors on the premature intestine and an abnormal gut microbiota incites a pro-inflammatory response in the intestinal mucosa and its underlying endothelium that leads to NEC. Central amongst the bacterial signalling receptors implicated in NEC development is the lipopolysaccharide receptor Toll-like receptor 4 (TLR4), which is expressed at higher levels in the premature gut than in the full-term gut. The high prenatal intestinal expression of TLR4 reflects the role of TLR4 in the regulation of normal gut development, and supports additional studies indicating that NEC develops in response to signalling events that occur in utero. This Review provides new evidence explaining the pathogenesis of NEC, explores new findings indicating that NEC development has origins before birth, and discusses future questions and opportunities for discovery in this field.

Chronological changes of serum exosome in preterm infants: A prospective study

BACKGROUND

Exosomes, which are observed in all human fluid, including serum, are nanosized extracellular vesicles with a mechanism of intercellular communication. Potential clinical applications of exosomes in neonatal diseases have recently been discussed. However, the characteristics of exosomes in serum during early infancy is unclear.

METHODS

In this prospective study, we evaluated the chronological changes in the concentration of serum-derived exosomes of 20 infants for 12 months after birth.

RESULTS

The average concentration of serum-derived exosomes was 4.6 × 10¹⁰ particles/mL at birth and increased significantly until the age of 48 weeks. There was a moderate correlation between the gestational age and the concentration of serum-derived exosomes both at birth (r = 0.54, P = 0.01) and during the 8 weeks after birth (r = 0.48, P < 0.001). A multivariable analysis showed that gestational age at birth was associated with the concentration of serum-derived exosomes at birth (partial regression coefficient, 0.86; 95% confidence interval, 0.37-1.37; P = 0.002).

CONCLUSIONS

The concentration of serum-derived exosomes in preterm infants increased both chronologically and by gestational age after birth. These basic data may help to further understand physiology of exosomes in preterm infants.

Primary peritoneal drainage in neonates with necrotizing enterocolitis associated with congenital heart disease: a single experience in a Brazilian tertiary center

Necrotizing enterocolitis (NEC) is a common condition in preterm infants. The risk factors that contribute to NEC include asphyxia, apnea, hypotension, sepsis, and congenital heart diseases (CHD). The objective of this study was to evaluate the association between the treatment (surgery or drainage) and unfavorable outcomes in neonates with NEC and congenital heart diseases (NEC+CHD). A 19-year retrospective cohort study was conducted (2000-2019). Inclusion criterion was NEC Bell II stage. Exclusion criteria were associated malformation or genetic syndrome and those who did not undergo echocardiography or had a Bell I diagnosis. We included 100 neonates: NEC (n=52) and NEC+CHD (n=48). The groups were subdivided into NEC patients undergoing surgery (NECS, n=31), NEC patients undergoing peritoneal drainage (NECD, n=19), NEC+CHD patients undergoing surgery (NECCAS, n=21), and NEC+CHD patients who were drained (NECCAD, n=29). Multivariate analysis was performed to estimate the relative risk of death and the length of stay. Covariates were birth weight and gestational age. The group characteristics were similar. The adjusted relative risk of death was higher in the drainage groups [NECD (Adj RR=2.70 (95%CI: 1.47; 4.97) and NECCAD (Adj RR=1.97 (95%CI: 1.08; 3.61)], and they had the shortest time to death: NECD=8.72 (95%CI: 3.10; 24.54) and NECCAD=5.32 (95%CI: 1.95; 14.44). We concluded that performing primary peritoneal drainage in neonates with or without CHD did not improve the number of days of life, did not decrease the risk of death, and was associated with a higher mortality in newborns with NEC and clinical instability.

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

BACKGROUND

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

OBJECTIVE

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSION

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

Stem Cells as Therapy for Necrotizing Enterocolitis: A Systematic Review and Meta-Analysis of Preclinical Studies

Background: Necrotizing enterocolitis (NEC) is the most common life-threatening gastrointestinal condition among very and extremely preterm infants. Stem cell therapy has shown some promising protective effects in animal models of intestinal injury, including NEC, but no systematic review has yet evaluated the preclinical evidence of stem cell therapy for NEC prevention or treatment. Methods: PubMed and EMBASE databases were searched for studies using an animal model of NEC with stem cells or their products. The SYRCLE tool was used for the assessment of risk of bias. A random-effects model was used to pool odds ratios (ORs) and 95% confidence interval (CI). Results: We screened 953 studies, of which nine (eight rat and one mouse models) met the inclusion criteria. All animal models induced NEC by a combination of hypothermia, hypoxia, and formula feeding. Risk of bias was evaluated as unclear on most items for all studies included. Meta-analysis found that both mesenchymal and neural stem cells and stem cell-derived exosomes reduced the incidence of all NEC (OR 0.22, 95% CI 0.16-0.32, k = 16), grade 2 NEC (OR 0.41, 95% CI 0.24-0.70, k = 16), and grade 3-4 NEC (OR 0.28, 95% CI 0.19-0.42, k = 16). k represents the number of independent effect sizes included in each meta-analysis. The effect of the exosomes was similar to that of the stem cells. Stem cells and exosomes also improved 4-day survival (OR 2.89 95% CI 2.07-4.04, k = 9) and 7-day survival (OR 3.96 95% CI 2.39-6.55, k = 5) after experimental NEC. Meta-analysis also found that stem cells reduced other indicators of intestinal injury. Conclusion: The data from this meta-analysis suggest that both stem cells and stem cell-derived exosomes prevented NEC in rodent experimental models. However, unclear risk of bias and incomplete reporting underline that poor reporting standards are common and hamper the reliable interpretation of preclinical evidence for stem cell therapy for NEC.

Risk of Necrotizing Enterocolitis Associated With the Single Nucleotide Polymorphisms VEGF C-2578A, IL-18 C-607A, and IL-4 Receptor α-Chain A-1902G: A Validation Study in a Prospective Multicenter Cohort

The etiology of necrotizing enterocolitis (NEC) is multifactorial and an underlying genetic predisposition to NEC is increasingly being recognized. A growing number of studies identified single nucleotide polymorphisms (SNPs) of selected genes with potential biological relevance in the development of NEC. However, few of these genetic studies have been replicated in validation cohorts. We aimed to confirm in a cohort of 358 preterm newborns (gestational age <30 weeks, 26 cases of NEC ≥ Bell stage II) the association with NEC of three candidate SNPs: the vascular endothelium growth factor (VEGF) C-2578A polymorphism (rs699947), the interleukin (IL)-18 C-607A polymorphism (rs1946518), and the IL-4 receptor α-chain (IL-4Rα) A-1902G polymorphism (rs1801275). We observed that allele and genotype frequencies of the three SNPs did not significantly differ between the infants with and without NEC. In contrast, the minor G-allele of the IL-4Rα A-1902G polymorphism was significantly less frequent in the group of 51 infants with the combined outcome NEC or death before 34 weeks postmenstrual age than in the infants without the outcome (0.206 vs. 0.331, P = 0.01). In addition, a significant negative association of the G-allele with the combined outcome NEC or death was found using the dominant (adjusted odds ratio, aOR: 0.44, 95% CI 0.21-0.92), recessive (aOR 0.15, 95% CI 0.03-0.74), and additive (aOR 0.46, 95% CI 0.26-0.80) genetic models. In conclusion our study provides further evidence that a genetic variant of the IL-4Rα gene may contribute to NEC.

Lactobacillus reuteri DSM 17938 Improves Feeding Intolerance in Preterm Infants

PURPOSE

Feeding tolerance is extremely important in preterm infants. This study aimed to evaluate whether preterm infants receiving Lactobacillus reuteri DSM 17938 would develop fewer symptoms of feeding intolerance. Secondary outcomes were duration of parenteral nutrition, time to reach full feeding, length of hospital stay, sepsis, necrotizing enterocolitis (NEC), diarrhea, and mortality.

METHODS

This double-blind randomized controlled trial of L. reuteri DSM 17938 versus placebo included 94 neonates with a gestational age of 28-34 weeks and birth weight of 1,000-1,800 g.

RESULTS

Feeding intolerance (vomiting and/or distension) was less common in the probiotic group than in the placebo group (8.5% vs. 25.5%; relative risk, 0.33; 95% confidence interval, 0.12-0.96; p=0.03). No significant intergroup differences were found in proven sepsis, time to reach full feeding, length of hospital stay, or diarrhea. The prevalence of NEC (stages 2 and 3) was 6.4% in the placebo group vs. 0% in the probiotic group (relative risk, 1.07; 95% confidence interval, 0.99-1.15; p=0.24). Mortality rates were 2.1% in the probiotic group and 8.5% in the placebo group, p=0.36).

CONCLUSION

The administration of L. reuteri DSM 17938 to preterm infants was safe and significantly reduced feeding intolerance. No significant differences were found in any other secondary outcomes.

Application of abdominal sonography in diagnosis of infants with necrotizing enterocolitis

The purpose of this study was to explore the diagnostic significance of abdominal sonography (AUS) in infants with Necrotizing enterocolitis (NEC) admitted to a neonatal intensive care unit to better evaluate the ability of AUS to differentiate necrotizing enterocolitis from other intestinal diseases.All patients diagnosed with NEC at the Department of General Surgery and Neonatal Surgery, Qilu Children's Hospital between 1st, Jun, 2010 and 30th, Dec, 2015. The logistic regression analysis and the area under receiver operating characteristic (ROC) curve (AUCs) were also used to identify the sonographic factors for diagnosing NEC.For the entire cohort of 91 patients, we divided these patients into suspected NEC (n = 35) group and definite NEC (n = 56) group. After adjusting for competing sonographic factors, we identified that thick bowel wall (more than 2.5 mm) (P = .013, OR: 1.246), intramural gas (pneumatosis intestinalis) (P = .002, OR:1.983), portal venous gas (P = .022, OR:1.655) and reduced peristalsis (P = .011, OR:1.667) were independent diagnostic factors associated with NEC. We built a logistic model to diagnose NEC according to the results of multivariable logistic regression analysis. We found the AUROC for thick bowel wall (more than 2.5 mm), intramural gas (pneumatosis intestinalis), portal venous gas and reduced peristalsis were significantly lower than the AUROC for the logistic model was 0.841 (95% CI: 0.669 to 0.946).We found that thick bowel wall (more than 2.5 mm), intramural gas (pneumatosis intestinalis), portal venous gas and reduced peristalsis were independent diagnostic factors associated with NEC. The logistic model was significantly superior to the single sonographic parameter for diagnosing NEC.

Physical examination score predicts need for surgery in neonates with necrotizing enterocolitis

OBJECTIVE

To evaluate the utility of a standardized physical exam score (PE-NEC) in predicting need for surgery or death in neonates with necrotizing enterocolitis (NEC).

METHODS

This prospective, multicenter, observational study was conducted from 3/1/14 to 2/29/16 with three regional perinatal centers in upstate New York. Infants with NEC Bell's Stage ≥ 2 had physical exams and laboratory data recorded at 12-24 h intervals for 48 h following diagnosis. PE-NEC score was comprised of seven components: bowel sounds, capillary refill time, abdominal wall erythema, girth, discoloration, induration, and tenderness. Surgical timing was determined by surgeons blinded to the PE-NEC score. Optimal sensitivity and specificity of PE-NEC score for surgery/death (primary outcome) was determined by receiver operating characteristic curve analysis.

RESULTS

Of 100 infants with NEC, 5 had pneumoperitoneum at diagnosis and were excluded yielding 95 for analyses. Of those, 35 infants experienced the primary outcome: 3 died from NEC prior to surgery and 32 had surgery (30 laparotomies, 2 drains). The PE-NEC score was found to be sensitive and specific for need for surgery/death (AUC = 0.89, 95% CI 0.82-0.97); a score of ≥3 had a sensitivity of 0.88 (95% CI 0.72-0.97), specificity of 0.81 (95% CI 0.69-0.90). All components of the PE-NEC score were more likely to be present among infants with surgical NEC or who died.

CONCLUSION

PE-NEC score is sensitive and specific in predicting need for surgery in infants with NEC and should be validated as a clinical decision-making tool.

Human breast milk-derived exosomes attenuate cell death in intestinal epithelial cells

Human breast milk has been shown to reduce the incidence of necrotizing enterocolitis (NEC). Breast milk has many components (immunoglobulins, proteins, fat, and, of recent interest, exosomes), but the specific component that affords protection against NEC is not known. Exosomes are small-nanometer vesicles that are rich in protein, lipid, and microRNA. Here, we hypothesized that human breast milk-derived exosomes can protect intestinal epithelial cells (IECs) from cell death. Human breast milk was collected, separated using ultracentrifugation, and quantified using NanoSight tracking analysis. Purified exosomes were added to IECs that had been treated with varying concentrations of H₂O₂. Cells were then incubated overnight with the human breast milk-derived exosomes and assessed for cell viability. Western blot analysis showed that both clathrin and CD81 were present in the purified sample. Oxidative stress using H₂O₂ caused a 50% decrease in cell viability and human breast milk-derived exosomes had a protective effect in IECs. In the presence of H₂O₂, exosomes had a statistically significant protective effect. The protection seen by human breast milk-derived exosomes was not attenuated by cycloheximide. Thus, human breast milk-derived exosomes allow IECs to be protected from oxidative stress, but the mechanism is still not clear. Exosomes derived from human breast milk are an attractive treatment concept for children with intestinal injury.

Comparison of abdominal radiographs and sonography in prognostic prediction of infants with necrotizing enterocolitis

PURPOSE

The purpose of this study was to investigate the comparison of AR and AUS in predicting prognosis in infants with necrotizing enterocolitis.

METHODS

All patients were diagnosed as NEC at the department of general surgery and neonatal surgery, Qilu children's hospital between 1st, Jun, 2010 and 30th, Dec, 2016. The logistic regression analysis and the area under ROC curve (AUC)s were also used to compare the prognostic values of radiograph and sonograph for NEC.

RESULTS

Throughout the study period, 86 preterm neonates were hospitalized with diagnosis of definite NEC. Among these patients, 39 infants (45.3%) required surgical treatment. After adjusting for competing sonographic factors, we identified that thick bowel wall (more than 2.5 mm) (p = 0.001, HR: 1.849), intramural gas (pneumatosis intestinalis) (p = 0.017, HR: 1.265), portal venous gas (p = 0.002, HR: 1.824), and reduced peristalsis (p = 0.021, HR: 1.544) were independent prognostic factors associated with NEC. After adjusting for competing radiographic factors, we identified that free peritoneal gas (p = 0.007, HR: 1.472), portal venous gas (p = 0.012, HR: 1.649), and dilatation and elongation (p = 0.025, HR: 1.327). Moreover, we found that the AUROC for AR logistic model was 0.745 (95% CI 0.629-0.812), which was significant lower than the AUS logistic model (AUROC: 0.857, 95% CI 0.802-0.946) for predicting prognosis of NEC.

CONCLUSIONS

In conclusion, we found that several radiographic and sonographic parameters were associated with the prognosis of patients with NEC. The AUS model based on the logistic regression analysis was significant superior to the AR model in the prognostic prediction of NEC.

High prevalence of cytomegalovirus infection in surgical intestinal specimens from infants with necrotizing enterocolitis and spontaneous intestinal perforation: A retrospective observational study

BACKGROUND

Necrotizing enterocolitis (NEC) is a severe, often fatal gastrointestinal emergency that predominantly affects preterm infants, and there is evidence that neonatal cytomegalovirus (CMV) infection may in some cases contribute to its pathogenesis.

OBJECTIVES

This study aimed to evaluate the prevalence of CMV in infants with NEC.

STUDY DESIGN

Seventy intestinal specimens from 61 infants with NEC, spontaneous intestinal perforation (SIP), or related surgical complications were collected at Karolinska University Hospital and Uppsala University Hospital, Sweden. Ten specimens from autopsied infants without bowel disease served as controls. Samples were analyzed for CMV immediate-early antigen (IEA), CMV late antigen (LA), 5-lipoxigenase (5LO) and CMV-DNA by immunohistochemistry (IHC) and in situ hybridization (ISH), respectively. In 10 index samples, CMV DNA was analyzed with Taqman PCR after laser capture microdissection (LCM) of cells positive for CMV IEA by IHC.

RESULTS

CMV IEA was detected by IHC in 57 (81%) and CMV LA in 45 (64%) of 70 intestinal specimens from index cases; 2 (20%) of 10 control specimens were positive for both antigens. 5LO was detected in intestinal tissue section obtained from all examined index and controls. CMV DNA was detected in 4 of 10 samples (40%) after LCM. By ISH, all 13 IHC-IEA-positive samples were positive for CMV DNA; however, 3 of 5 IHC-IEA-negative samples (60%) were also positive.

CONCLUSIONS

CMV-specific antigens and CMV DNA were highly prevalent in intestinal specimens from infants with NEC, SIP, and related surgical complications. Our findings provide further evidence that neonatal CMV infection contributes to the pathogenesis of these diseases and may affect patient outcome.

Association between the p.Thr1406Asn polymorphism of the carbamoyl-phosphate synthetase 1 gene and necrotizing enterocolitis: A prospective multicenter study

The p.Thr1406Asn (rs1047891) polymorphism of the carbamoyl-phosphate synthetase 1 (CPS1) gene has been linked to functional consequences affecting the downstream availability of the nitric oxide precursor L-arginine. L-arginine concentrations are decreased in preterm infants with necrotizing enterocolitis (NEC). In this multicenter prospective study, we investigated the association of the p.Thr1406Asn polymorphism with NEC in 477 preterm infants (36 cases of NEC) from 4 European neonatal intensive care units (Maastricht, Las Palmas de Gran Canaria, Mantova, and Milan). Allele and genotype frequencies of the p.Thr1406Asn polymorphism did not significantly differ between the infants with and without NEC. In contrast, the minor A-allele was significantly less frequent in the group of 64 infants with the combined outcome NEC or death before 34 weeks of corrected gestational age than in the infants without the outcome (0.20 vs. 0.31, P = 0.03). In addition, a significant negative association of the A-allele with the combined outcome NEC or death was found using the dominant (adjusted odds ratio, aOR: 0.54, 95% CI 0.29–0.99) and the additive (aOR 0.58, 95% CI 0.36–0.93) genetic models. In conclusion, our study provides further evidence that a functional variant of the CPS1 gene may contribute to NEC susceptibility.

[Risk factors for concurrent sepsis in neonates with necrotizing enterocolitis]

OBJECTIVE

To investigate the risk factors for concurrent sepsis in neonates with necrotizing enterocolitis (NEC).

METHODS

A retrospective analysis was performed for the clinical data of 273 neonates with NEC. The risk factors for concurrent sepsis were analyzed from the aspects of perinatal factors and treatment regimen before the diagnosis of NEC.

RESULTS

The incidence rate of concurrent sepsis in NEC was 32.2% (88/273). The neonates with stage III NEC had a significantly higher incidence rate of concurrent sepsis than those with stage II NEC (69.0% vs 15.9%; P<0.05). Of all neonates with sepsis, 62.5% experienced sepsis within 3 days after the diagnosis of NEC, and 37.5% experienced sepsis more than 3 days after the diagnosis. Compared with those without concurrent sepsis, the neonates with concurrent sepsis had significantly lower gestational age and birth weight (P<0.05). The neonates who had scleredema, had stage III NEC, needed gastrointestinal decompression after the diagnosis of NEC, and experienced a long time of gastrointestinal decompression tended to develop sepsis more easily (P<0.05). Scleredema (OR=9.75, 95%CI: 2.84-33.52, P<0.001), stage III NEC (OR=12.94, 95%CI : 6.82-24.55, P<0.001), and gastrointestinal decompression (OR=2.27, 95%CI: 1.14-4.5, P=0.02) were independent risk factors for concurrent sepsis in NEC.

CONCLUSIONS

Scleredema, stage III NEC, and gastrointestinal decompression are independent risk factors for concurrent sepsis in neonates with NEC.

Bowel Perforation in Premature Infants with Necrotizing Enterocolitis: Risk Factors and Outcomes

We aim to determine risk factors and clinical outcomes for bowel perforation in premature infants with NEC. We analyzed clinical data of 57 cases of premature infants with NEC at our NICU between January 2010 and December 2012. Based on the presence of bowel perforation, we divided these infants into two groups: perforated NEC group (n = 10) and nonperforated NEC group (n = 47). We compared general information, clinical characteristics, and laboratory findings between groups. The perforated NEC group, compared to the nonperforated NEC group, had significantly lesser gestational age, lower birth weight, higher prevalence of apnea, mechanical ventilation, sepsis and shock, lower blood pH, higher levels of blood glucose, abnormal WBC count and thrombocytopenia, and elevated CRP (all P < 0.05). Moreover, the perforated NEC group had significantly longer durations of fasting and TPN usage, higher incidences of EUGR and cholestasis, longer duration of antibiotics, higher frequency of advanced antibiotics use, and poorer prognosis than the nonperforated NEC group (all P < 0.05). Bowel perforation in premature infants with NEC was associated with multiple risk factors. Early identification of some of these risk factors in premature infants with NEC may help implement early intervention to reduce the incidence of bowel perforation and thereby improve the prognosis.

Probiotic administration can prevent necrotizing enterocolitis in preterm infants: A meta-analysis

PURPOSE

Necrotizing enterocolitis (NEC) is the most common gastrointestinal emergency in preterm infants, affecting ~6-7% of very-low-birth-weight (VLBW) infants. Early intervention and aggressive treatment has improved clinical outcomes, but considerable morbidity continues to accrue to NEC survivors. This meta-analysis examines the impact of probiotics on the incidence of NEC and complications among VLBW infants.

METHODS

A comprehensive literature search for all published randomized control trials (RCTs) assessing the use of probiotics to prevent NEC in VLBW infants was conducted using PubMed, Cochrane Central Registry of Controlled Trials, and Google Scholar (1966-2014). The incidences of NEC, sepsis, overall mortality, and time to reach full enteral feeds were analyzed.

RESULTS

20 RCTs involving 5982 preterm VLBW infants were analyzed. Risk of NEC was reduced by 49.1% (RR=0.509; 95% CI, 0.385-0.672; p<0.001), and overall mortality by 26.9% among infants receiving probiotics (RR=0.731; 95% CI, 0.577-0.926; p=0.009). An 8.1% reduction in sepsis was also observed in infants receiving probiotics (RR=0.919; 95% CI, 0.823-1.027; p=0.137). Time to reach full enteral feeds was reduced by 1.2 days among infants receiving probiotics (MD: -1.217; 95% CI, -2.151 to -0.283; p=0.011).

CONCLUSION

The use of probiotic supplementation in preterm VLBW infants is associated with a significant reduction in the risk of NEC and overall mortality. Additional studies are required to determine the optimal genus, species, and dose of probiotic.

Probiotics Reduce Necrotizing Enterocolitis Severity in HIV-exposed Premature Infants

OBJECTIVE

To assess the effect of probiotics on the incidence of necrotizing enterocolitis (NEC) in premature infants born to human immunodeficiency virus (HIV)-positive and HIV-negative women.

PATIENTS AND METHODS

HIV-exposed and HIV-unexposed premature infants were randomized to either the probiotic or the placebo group. The probiotic consisted of 1 × 10(9) colony-forming units, Lactobacillus rhamnosus GG and Bifidobacterium infantis per day.

RESULTS

In total, 74 HIV-exposed and 110 HIV-unexposed infants were enrolled and randomized. The incidence of death [4 (5.4%) vs. 7 (6%); p = 0.79] and NEC [4 (5%) vs. 5 (5%); p = 0.76] did not differ significantly between the HIV-exposed and HIV-unexposed groups. A significant difference was found for total NEC incidence between the study and control groups [3 (3%) vs. 6 (6%); p = 0.029]. The incidence of NEC in the HIV-exposed group differed significantly [Bells I 2 (5%) vs. Bells III 2 (5%); p = 0.045).

CONCLUSION

Probiotic supplementation reduced the incidence of NEC in the premature very low birth weight infants; however, results failed to show a lower incidence of NEC in HIV-exposed premature infants. A reduction in the severity of disease was found in the HIV-exposed study group.

The metabolomics of necrotising enterocolitis in preterm babies: an exploratory study

OBJECTIVE

No single diagnostic investigation is currently available for necrotising enterocolitis (NEC). We implemented a novel, untargeted, exploratory study to determine whether metabolomics can reveal early biomarker(s) of NEC. The effect of gestational age on the metabolome was also investigated.

METHODS

Two serum samples were obtained from 12 preterm babies (born <30 weeks gestation) and eight term controls: sample "A" at ≤1 week of age and sample "B" once fully fed. Samples were subjected to gas chromatography-mass spectrometry. Metabolomic data was analysed by principal component analysis (PCA), univariate and network analysis.

RESULTS

Sixteen metabolite features significantly differed when B samples were compared between preterm babies who subsequently developed NEC and preterm/term controls (p value <0.05). Of these seven metabolites were linked to up-regulation of IL-1β. Significant differences in 54 metabolite features (p value <0.05) were observed between preterm and term metabolomes. Of these, 12 metabolite features were linked to one network involved in carbohydrate/lipid metabolism (p = 1 × 10(-30)).

CONCLUSIONS

Metabolomic differences were observed in preterm babies at risk of NEC. However, sample sizes were insufficient to confidently identify a biomarker. Network modelling of preterm and term metabolomes suggest possible nutritional deficiency and altered pro-insulin action in preterm babies.

Necrotizing enterocolitis: a clinical review on diagnostic biomarkers and the role of the intestinal microbiota

Necrotizing enterocolitis (NEC) remains one of the most frequent gastrointestinal diseases in the neonatal intensive care unit, with a continuing unacceptable high mortality and morbidity rates. Up to 20% to 40% of infants with NEC will need surgical intervention at some point. Although the exact pathophysiology is not yet elucidated, prematurity, use of formula feeding, and an altered intestinal microbiota are supposed to induce an inflammatory response of the immature intestine. The clinical picture of NEC has been well described. However, an early diagnosis and differentiation against sepsis is challenging. Besides, it is difficult to timely identify NEC cases that will deteriorate and need surgical intervention. This may interfere with the most optimal treatment of infants with NEC. In this review, we discuss the pathogenesis, diagnosis, and treatment of NEC with a focus on the role of microbiota in the development of NEC. An overview of different clinical prediction models and biomarkers is given. Some of these are promising tools for accurate diagnosis of NEC and selection of appropriate therapy.

Bacterial diversity and Clostridia abundance decrease with increasing severity of necrotizing enterocolitis

BACKGROUND

Necrotizing enterocolitis (NEC) is a devastating neonatal gastrointestinal disease that primarily affects premature infants. It is characterized by bowel inflammation and necrosis. In spite of extensive research, there has been little progress in decreasing the incidence or mortality of NEC over the past three decades. The exact etiology of NEC has not been identified. However, it is believed to result from an inappropriate immune response to gut microbiota. Using 454-pyrosequencing analyses of 16S rRNA genes that were PCR-amplified from stool DNA specimens, we compared the gut microbiota of infants with NEC to matched controls without NEC. The infants with NEC were then categorized into three subgroups based on severity: mild, severe, and lethal. We compared the microbiota among these subgroups and between each severity group and appropriate controls.

RESULTS

Bacterial diversity and the relative abundance of Actinobacteria and Clostridia were significantly lower in NEC specimens compared to controls. The absence of Clostridia was significantly associated with NEC. Microbial diversity and Clostridia abundance and prevalence decreased with increasing severity of NEC.

CONCLUSIONS

Low bacterial diversity in stool specimens may be indicative of NEC and the severity of NEC. The low bacterial diversity, and the lack of Clostridia in lethal specimens, could indicate that the presence of a diverse bacterial population in the gut as well as the presence of taxa such as Clostridia may play a role in attenuating inflammation leading to NEC.

Gastric residual evaluation in preterm neonates: a useful monitoring technique or a hindrance?

It is routine practice in most neonatal intensive care units to measure the volume and color of gastric residuals (GRs) prior to enteral bolus feedings in preterm very low birth weight infants. However, there is paucity of evidence supporting the routine use of this technique. Moreover, owing to the lack of uniform standards in the management of GRs, wide variations exist as to what constitutes significant GR volume, the importance of GR color and frequency of GR evaluation, and the color or volume standards that dictate discarding or returning GRs. The presence of large GR volumes or green-colored residuals prior to feeding often prompts subsequent feedings to be withheld or reduced because of possible necrotizing enterocolitis resulting in delays in enteral feeding. Cessation or delays in enteral feeding may result in extrauterine growth restriction, a known risk factor for poor neurodevelopmental and growth outcomes in preterm very low birth weight infants. Although some neonatal intensive care units are abandoning the practice of routine GR evaluation, little evidence exists to support the discontinuation or continuation of this practice. This review summarizes the current state of GR evaluation and underlines the need for a scientific basis to either support or refute the routine evaluation of GRs.

High-mobility group box 1 (HMGB1) in childhood: from bench to bedside

High-mobility group box protein 1 (HMGB1) is a nonhistone nuclear protein that has a dual function. Inside the cell, HMGB1 binds DNA, regulating transcription and determining chromosomal architecture. Outside the cell, HMGB1 activates the innate system and mediates a wide range of physiological and pathological responses. HMGB1 exerts these actions through differential engagement of multiple surface receptors, including Toll-like receptor (TLR)2, TLR4, and receptor for advanced glycation end products (RAGE). HMGB1 is implicated as a late mediator of sepsis and is also involved in inflammatory and autoimmune diseases, such as rheumatoid arthritis and systemic lupus erythematosus. Interestingly, HMGB1 was associated with tumor progression, becoming a potential therapeutic target, due to its involvement in the resistance to chemotherapy. Its implication on the pathogenesis of systemic vasculitis and inflammatory bowel diseases has also been evaluated. Moreover, it regulates neuroinflammation after traumatic brain injuries or cerebral infectious diseases. The aim of this review is to analyze these different roles of HMGB1, both in physiological and pathological conditions, discussing clinical and scientific implications in the field of pediatrics.

CONCLUSION

HMGB1 plays a key role in several pediatric diseases, opening new scenarios for diagnostic biomarkers and therapeutic strategies development.

A meta-analysis of probiotics for preventing necrotizing enterocolitis in preterm neonates

Necrotizing enterocolitis (NEC) is one of the most common acquired diseases of the gastrointestinal tract in preterm infants. Some randomized, controlled trials (RCTs) have indicated that probiotics may potentially lower the incidence of NEC and mortality. However, debate still remains about the safety of probiotics and their influence on normal infant growth. We performed this meta-analysis to assess the safety and benefits of probiotic supplementation in preterm infants. We searched in PubMed, Embase, and Cochrane databases for English references, and in Wanfang, VIP, and CNKI databases for Chinese references. Ultimately, 27 RCTs (including 9 Chinese articles) were incorporated into this meta-analysis. Relative risk (RR) and weighted mean difference (WMD) were calculated using a random-effects or fixed-effects model, depending on the data type and heterogeneity. A total of 6655 preterm infants, including the probiotic group (n=3298) and the placebo group (n=3357), were eligible for inclusion in this meta-analysis. For Bell stage ≥I and gestational age <37 weeks, risk of NEC incidence was significantly lower in the probiotic group [RR=0.35, 95% confidence interval (CI)=0.27-0.44, P<0.00001]. For Bell stage ≥II or gestational age <34 weeks, there were likewise significant differences between the probiotic and placebo groups concerning NEC incidence (RR=0.34, 95%CI=0.25-0.48, P<0.00001; and RR=0.39, 95%CI=0.27-0.56, P<0.00001). Risk of death was significantly reduced in the probiotic group (RR=0.58, 95%CI=0.46-0.75, P<0.0001). In contrast, there was no significant difference concerning the risk of sepsis (RR=0.94, 95%CI=0.83-1.06, P=0.31). With respect to weight gain and the age at which infants reached full feeds, no significant differences were found between the probiotic and placebo groups (WMD=1.07, 95%CI=−0.21-2.34, P=0.10; and WMD=−1.66, 95%CI=−3.6-0.27, P=0.09). This meta-analysis has shown that, regardless of gestational age and NEC stage, probiotic supplementation could significantly reduce the risk of NEC in preterm infants. Analysis also indicated that such supplementation did not increase the incidence risk of sepsis or of mortality. Finally, the study showed that probiotic supplementation may have no adverse effect on normal feeding and growth.

The effect of vascular endothelial growth factor overexpression in experimental necrotizing enterocolitis

PURPOSE

Necrotizing enterocolitis (NEC) is a serious condition, predominantly observed in premature infants. We used an experimental NEC model to investigate the effects of vascular endothelial growth factor (VEGF) cloned into a plasmid.

MATERIALS AND METHODS

Twenty-four newborn Wistar albino rats were randomized equally into three groups as follows: control, NEC and NEC+VEGF. NEC was induced by hyperosmolar enteral formula feeding, exposure to hypoxia/reoxygenation and cold stress. In the NEC+VEGF group, VEGF (1 μg) incorporated into plasmid (2 μg) was administered subcutaneously once daily for a total of 3 days starting on the first day of the NEC procedure. All rats were sacrificed on the 4th day of life, and the specimens were harvested for histopathological and biochemical examinations [including tissue oxidative stress (malondialdehyde and nitric oxide), inflammation (myeloperoxidase, interleukin-6 and tumor necrosis factor alpha) and apoptosis (caspase-3 activity) parameters].

RESULTS

In the NEC+VEGF group, tissue malondialdehyde, nitric oxide, interleukin-6, tumor necrosis factor alpha levels and caspase-3 activity were significantly decreased. In addition, the myeloperoxidase level was increased compared to that of the NEC group (p < 0.05). Histopathologically, VEGF overexpression enhanced angiogenesis, alleviated villous atrophy and tissue edema (p < 0.05).

CONCLUSION

VEGF overexpression with plasmids seems to be a promising approach in the management of NEC.

Gastric pneumatosis and rupture caused by lactobezoar

BACKGROUND

Lactobezoar is a compact mass of inspissated, undigested milk. Most often it is located in the stomach but it may also be located in other parts of the intestine. It is the most common type of bezoar in infancy. Reported herein are two cases of this rare condition mimicking necrotizing enterocolitis.

METHOD

Data on two complicated cases of lactobezoar were retrospective analyzed.

RESULTS

The first case involved a female infant, born at 37 weeks 2 days gestation with a birthweight of 3050 g, and multiple antenatal known congenital defects. Due to esophageal atresia she was given a gastrostomy on the second day of life. After 20 days of continuous feeding with formula feeding she developed food intolerance and clinical signs of a severe sepsis. On examination the abdomen was severely distended and tender at palpation. No palpable mass was noted at examination. Signs of hemodynamic instability and sepsis evolved. Plain abdominal X-ray showed a pneumatosis of the stomach matching necrotizing enterocolitis (NEC). During emergency laparotomy a gastric bezoar was seen and removed. The postoperative course was complicated by prolonged motility disturbance of the stomach. For a long time she was fed through a jejunostomy. The second case involved a female infant born at 26 weeks 4 days (birthweight 1040 g) who became progressively septic on the day 6 of life. On examination she had a tender and distended abdomen, and abdominal X-ray showed intra-abdominal air, consistent with a gastrointestinal perforation. On emergency laparotomy a perforation was seen at the back of the stomach, due to a lactobezoar, with only a little necrosis surrounding it. Surgical treatment consisted of extraction of the lactobezoar and closure of the perforation at the back of the stomach. Two days after the initial surgery, she developed a leakage of the suture anastomosis and another laparotomy was performed. A drain was left near the stomach. After 2 weeks she recovered quickly and feeding was initiated at day 21 with good outcome after 3 months.

CONCLUSION

Factors associated with the development of lactobezoar are prematurity, low birthweight, disturbed gastric emptying, hypercaloric and hyperosmolaric milk compositions. It is important to realize that lactobezoar formation can occur in preterm and full-term infants, receiving either breast milk or formula, even when only minimal enteral feeding is given. Early recognition and treatment of this condition is critical. If a lactobezoar is not detected in an early phase, patients can deteriorate very quickly into a condition mimicking NEC.

A pig model of the preterm neonate: anthropometric and physiological characteristics

BACKGROUND

Large animal models are an essential tool in the development of rationally-based new clinical therapies for preterm infants. We provide a description of the newborn pig as a model of the preterm neonate in terms of growth parameters, physiology and the requirement for intensive care over a range of gestational ages.

METHODS

Twenty-nine litters of piglets (n = 298) were delivered by caesarean section at six timepoints during gestation from 91d to 113d (term = 115d). Two groups, at 91 and 97d gestation, also received maternal glucocorticoid treatment. At four of these timepoints, piglets (n = 79) were ventilated, sedated and monitored using standard neonatal intensive care techniques for up to 8 h in various experimental protocols.

RESULTS

Body weight increased from mean 697 g (SD 193) at 91d gestation to 1331 g (SD 368) at 113d gestation. Piglets delivered at 97d gestation were able to be resuscitated and kept alive for at least 8 h on respiratory support after surfactant administration. Maternal glucocorticoid treatment 48 h and 24 h hours prior to delivery reduced the requirement for ventilator support and improved cardiovascular stability.

CONCLUSION

The pig provides a relevant model for the study of human preterm physiology and for investigation of novel therapies to improve outcomes.

Neonatal sepsis due to coagulase-negative staphylococci

Neonates, especially those born prematurely, are at high risk of morbidity and mortality from sepsis. Multiple factors, including prematurity, invasive life-saving medical interventions, and immaturity of the innate immune system, put these infants at greater risk of developing infection. Although advanced neonatal care enables us to save even the most preterm neonates, the very interventions sustaining those who are hospitalized concurrently expose them to serious infections due to common nosocomial pathogens, particularly coagulase-negative staphylococci bacteria (CoNS). Moreover, the health burden from infection in these infants remains unacceptably high despite continuing efforts. In this paper, we review the epidemiology, immunological risk factors, diagnosis, prevention, treatment, and outcomes of neonatal infection due to the predominant neonatal pathogen CoNS.

A clinical perspective of necrotizing enterocolitis: past, present, and future

Necrotizing enterocolitis (NEC) primarily affects premature infants. It is less common in term and late preterm infants. The age of onset is inversely related to the postmenstrual age at birth. In term infants, NEC is commonly associated with congenital heart diseases. NEC has also been associated with other anomalies. More than 85% of all NEC cases occur in very low birth weight infants or in very premature infants. Despite incremental advances in our understanding of the clinical presentation and pathophysiology of NEC, universal prevention of this disease continues to elude us even in the twenty-first century.