Interleukin-8 predicts 60-day mortality in premature infants with necrotizing enterocolitis

Methods of identifying surgical Necrotizing Enterocolitis-a systematic review and meta-analysis

BACKGROUND

Current data suggests potential benefit of earlier surgery for necrotizing enterocolitis (NEC) however this requires accurate prognostication early in the disease course. This study aims to identify and determine the effectiveness of previously reported methods or tests for the identification of surgical NEC.

METHODS

Systematic review and meta-analysis with registration on PROSPERO including articles describing a method of identifying surgical NEC. Outcomes of interest were effectiveness and repeatability of index test.

RESULTS

Of the 190 full-text articles screened, 90 studies were included which contained 114 methods of identifying surgical NEC in 9546 infants. Of these methods, 44 were a scoring system, 37 a single biomarker, 24 an imaging method, and 9 an invasive method. Sensitivity and specificity ranged from 12.8-100% to 13-100%, respectively. Some methods (9.6%) provided insufficient methods for repeatability within clinical practice or research. Meta-analyses were possible for only 2 methods, the metabolic derangement 7 score and abdominal ultrasound.

CONCLUSIONS

A range of methods for identifying surgical NEC have been identified with varying overall performance and uncertainties about reproducibility and superiority of any method. External validation in large multicentre datasets should allow direct comparison of accuracy and prospective study should evaluate impact on clinical outcomes.

IMPACT

Earlier identification of need for surgery in necrotizing enterocolitis (NEC) has the potential to improve the unfavourable outcomes in this condition. As such, many methods have been developed and reported to allow earlier identification of surgical NEC. This study is the first synthesis of the literature which identifies previously reported methods and the effectiveness of these. Many methods, including scoring systems and biomarkers, appear effective for prognostication in NEC and external validation is now required in multicentre datasets prior to clinical utility.

Recent advances in our understanding of NEC diagnosis, prognosis and surgical approach

Necrotising enterocolitis (NEC) remains a devasting condition that has seen limited improvement in outcomes in recent years. The incidence of the disease is increasing as more extremely premature infants survive. NEC is responsible for 1 in 10 neonatal deaths and up to 61% of survivors have significant neurodevelopmental delay. The aim of this review is to highlight recent advances in diagnosis, prognosis and surgical approach in this condition. Many recent studies have reported novel methods of diagnosis of NEC with the aim of earlier and more accurate identification. These include imaging and machine learning techniques. Prognostication of NEC is particularly important to allow earlier escalation of therapy. Around 25% of infants with NEC will require surgery and recent data has shown that time from disease onset to surgery is greater in infants whose indication for surgery is failed medical management, rather than pneumoperitoneum. This indication was also associated with worse outcomes compared to pneumoperitoneum. Ongoing research has highlighted several new methods of disease prognostication which includes differentiating surgical from medical NEC. Finally, recent randomised controlled trials in surgical technique are discussed along with the implications of these for practice. Further, high quality research utilising multi-centre collaborations and high fidelity data from electronic patient records is needed to address the issues discussed and ultimately improve outcomes in NEC.

The fetal response to maternal inflammation is dependent upon maternal IL-6 in a murine model

BACKGROUND

The induction of maternal inflammation in mice leads to fetal injury that is believed to be IL-6 dependent. The fetal inflammatory response, defined by elevated fetal or amniotic fluid IL-6, has been described as a potential mechanism for subsequent fetal injury. The role of maternal IL-6 production and signaling in the fetal IL-6 response is currently unclear.

METHODS

Genetic and anti-IL-6 antibody strategies were used to systematically block the maternal IL-6 response during inflammation. Chorioamnionitis was induced using intraperitoneal injection of lipopolysaccharide (LPS) at mid gestation (E14.5) and late gestation (E18.5). This model was used in pregnant C57Bl/6 dams, IL6-/- dams, C57Bl/6 dams treated with anti-IL-6 (blocks both classical and trans-signaling) or anti-gp130 antibodies (blocks trans-signaling only) and IL6+/- dams. Six hours following LPS injection, maternal serum, placental tissue, amniotic fluid and fetal tissue or serum were collected. A bead-based multiplex assay was used to evaluate levels of IL-6, KC, IL-1β, TNF, IL-10, IL-22, IFN-γ, IL-13 and IL-17A.

RESULTS

Chorioamnionitis in C57Bl/6 dams was characterized by elevated maternal serum levels of IL-6, KC and IL-22 with litter loss during mid gestation. The fetal response to maternal inflammation in C57Bl/6 mice was primarily characterized by elevated levels of IL-6, KC and IL-22 in the placenta, amniotic fluid and fetus during both mid and late gestation. A global IL-6 knockout (IL6-/-) eradicated the maternal, placental, amniotic fluid and fetal IL-6 response to LPS during mid and late gestation and improved litter survival, while minimally influencing the KC or IL-22 responses. Blocking maternal classical IL-6 signaling in C57Bl/6 dams at the time of LPS exposure diminished the maternal, placental, amniotic fluid and fetal IL-6 response during mid and late gestation, while blocking maternal IL-6 trans-signaling only affected fetal IL-6 expression. To evaluate whether maternal IL-6 was crossing the placenta and reaching the fetus, IL-6+/- dams were utilized in the chorioamnionitis model. IL-6+/- dams mounted a systemic inflammatory response following injection with LPS, characterized by elevated IL-6, KC and IL-22. IL-6-/- pups born to IL6+/- dams had decreased amniotic fluid levels of IL-6 and undetectable levels of fetal IL-6 compared to IL-6+/+ littermate controls.

CONCLUSION

The fetal response to systemic maternal inflammation is dependent upon maternal IL-6 signaling, but maternal IL-6 is not crossing the placenta and reaching the fetus at detectable levels.

Screening inflammatory protein biomarkers on premature infants with necrotizing enterocolitis

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Variations in the Composition of Human Milk Oligosaccharides Correlates with Effects on Both the Intestinal Epithelial Barrier and Host Inflammation: A Pilot Study

Background: Human milk oligosaccharides are complex, non-digestible carbohydrates that directly interact with intestinal epithelial cells to alter barrier function and host inflammation. Oligosaccharide composition varies widely between individual mothers, but it is unclear if this inter-individual variation has any impact on intestinal epithelial barrier function and gut inflammation. Methods: Human milk oligosaccharides were extracted from the mature human milk of four individual donors. Using an in vitro model of intestinal injury, the effects of the oligosaccharides on the intestinal epithelial barrier and select innate and adaptive immune functions were assessed. Results: Individual oligosaccharide compositions shared comparable effects on increasing transepithelial electrical resistance and reducing the macromolecular permeability of polarized (Caco-2Bbe1) monolayers but exerted distinct effects on the localization of the intercellular tight junction protein zona occludins-1 in response to injury induced by a human enteric bacterial pathogen Escherichia coli, serotype O157:H7. Immunoblots showed the differential effects of oligosaccharide compositions in reducing host chemokine interleukin 8 expression and inhibiting of p38 MAP kinase activation. Conclusions: These results provide evidence of both shared and distinct effects on the host intestinal epithelial function that are attributable to inter-individual differences in the composition of human milk oligosaccharides.

Biomarkers of gut injury in neonates - where are we in predicting necrotising enterocolitis?

Despite advances in neonatal care Necrotising Enterocolitis (NEC) continues to have a significant mortality and morbidity rate, and with increasing survival of those more immature infants the population at risk of NEC is increasing. Ischaemia, reperfusion, and inflammation underpin diseases affecting intestinal blood flow causing gut injury including Necrotising Enterocolitis. There is increasing interest in tissue biomarkers of gut injury in neonates, particularly those representing changes in intestinal wall barrier and permeability, to determine whether these could be useful biomarkers of gut injury. This article reviews current and newly proposed markers of gut injury, the available literature evidence, recent advances and considers how effective they are in clinical practice. We discuss each biomarker in terms of its effectiveness in predicting NEC onset and diagnosis or predicting NEC severity and then those that will aid in surveillance and identifying those infants are greatest risk of developing NEC.

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

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

Surgical necrotizing enterocolitis: Association between surgical indication, timing, and outcomes

BACKGROUND/PURPOSE

Despite improvements in neonatal care the outcomes of Necrotizing Enterocolitis (NEC) remain unchanged over previous decades. The study aims to explore whether different indications for surgical intervention in NEC are associated with timing of surgery and outcomes.

METHODS

Population-based, prospective, observational study of all 27 paediatric surgical centres in the United Kingdom and Ireland identified using the British Association of Paediatric Surgeons Congenital Anomalies Surveillance System from 1st February 2013 to 28th February 2014. Infants were included if they had NEC and underwent first surgical intervention within 7 days of diagnosis. Primary outcomes were death, parenteral nutrition requirement or a composite outcome of death or PN requirement at 28 days post surgery.

RESULTS

There were 133 infants meeting inclusion criteria. Indications for surgery were bowel perforation (n = 67), suspected necrotic bowel without bowel perforation and not deemed to have failed medical management (n = 20), those who had failed medical management (n = 42) and a palpable mass without any other indication (n = 4). Failed medical treatment as an indication for surgery was associated with an increased time to surgery of 30.28 (95% CI 13.46-47.10) hours from those whose indication was perforation and was also the strongest predictor of PN requirement or death at 28 days post-surgery (OR 4.54 [1.59-13.0]).

CONCLUSIONS

Failed medical treatment as an indication for surgery for NEC is associated with poor outcome. Earlier intervention in these infants represents a potential opportunity to improve outcomes in this population.

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

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

Lyophilization of human amniotic fluid is feasible without affecting biological activity

BACKGROUND

Fetal swallowing of human amniotic fluid (hAF) containing trophic factors (TFs) promotes gastrointestinal tract (GIT) development. Preterm birth interrupts hAF swallowing, which may increase the risk of necrotizing enterocolitis (NEC). Postnatally, it is difficult to replicate fetal swallowing of hAF due to volume. We aimed to evaluate whether hAF lyophilization is feasible and its effect on hAF-borne TFs.

METHODS

We collected hAF (n = 16) from uncomplicated pregnancies. hAF was divided into three groups: unprocessed control (C), concentration by microfiltration (F), and by dialysis and lyophilization (L). EGF, HGF, GM-CSF, and TGF-α were measured in each group by multiplex assay. Bioavailability of TFs was measured by proliferation and LPS-induced IL-8 production by intestinal epithelial cells FHs74.

RESULTS

After dialysis/lyophilization, GM-CSF and TGF-α were preserved with partial loss of EGF and HGF. hAF increased cell proliferation and reduced LPS-induced IL-8 production compared to medium alone. Compared to control, dialysis/lyophilization and filtration of hAF increased FHs74 cell proliferation (p < 0.001) and decreased LPS-induced IL-8 production (p < 0.01).

CONCLUSIONS

Lyophilization and filtration of hAF is feasible with partial loss of TFs but maintains and even improves bioavailability of TFs measured by proliferation and LPS-induced IL-8 production by FHs74.

Cardiac and Inflammatory Necrotizing Enterocolitis in Newborns Are Not the Same Entity

Background: Necrotizing enterocolitis (NEC) is an often-fatal neonatal disease involving intestinal hyperinflammation leading to necrosis. Despite ongoing research, (1) conflicting results and (2) comorbidities of NEC patients make early NEC detection challenging and may complicate therapy development. Most research suggests that NEC pathogenesis is multifactorial, involving a combination of (1) gut prematurity; (2) abnormal bacterial colonization; and (3) ischemia-reperfusion (I/R) injury. As neutrophil extracellular traps (NETs) partially mediate I/R injury and drive inflammation in NEC, we hypothesized that NETs contribute to NEC development; particularly in cardiac patients. Methods: A retrospective analysis of baseline characteristics, clinical signs, laboratory parameters, and imaging was conducted for surgically verified NEC cases over 10 years. Patients were stratified into two groups: (1) prior medically or surgically treated cardiac disease (cardiac NEC) and (2) no cardiac comorbidities (inflammatory NEC). Additionally, histology was reassessed for neutrophil activation and NETs formation. Results: A total of 110 patients (cNEC 43/110 vs. iNEC 67/110) were included in the study, with cNEC neonates being significantly older than iNEC neonates (p = 0.005). While no significant differences were found regarding clinical signs and imaging, laboratory parameters revealed that cNEC patients have significantly increased leucocyte (p = 0.024) and neutrophil (p < 0.001) counts. Both groups also differed in pH value (p = 0.011). Regarding histology: a non-significant increase in staining of myeloperoxidase within the cNEC group could be found in comparison to iNEC samples. Neutrophil elastase (p = 0.012) and citrullinated histone H3 stained (p = 0.041) slides showed a significant markup for neonates diagnosed with cNEC in comparison to neonates with iNEC. Conclusion: The study shows that many standardized methods for diagnosing NEC are rather unspecific. However, differing leucocyte and neutrophil concentrations for iNEC and cNEC may indicate a different pathogenesis and may aid in diagnosis. As we propose that iNEC is grounded rather in sepsis and neutropenia, while cNEC primarily involves I/R injuries, which involves neutrophilia and NETs formation, it is plausible that I/R injury due to interventions for cardiac comorbidities results in pronounced neutrophil activation followed by a hyperinflammation reaction and NEC. However, prospective studies are necessary to validate these findings and to determine the accuracy of the potential diagnostic parameters.

The Protective Influence of Chondroitin Sulfate, a Component of Human Milk, on Intestinal Bacterial Invasion and Translocation

BACKGROUND

Human milk is known to be protective against necrotizing enterocolitis, a devastating intestinal inflammatory disease affecting the preterm population. Although the pathogenesis of necrotizing enterocolitis is yet to be solidified, intestinal integrity dysfunction, bacterial invasion and/or translocation, and inflammation may play important roles. Glycosaminoglycans, compounds naturally prevalent in both human milk and the intestine, are thought to be anti-inflammatory and capable of altering bacterial interactions within the gut.

RESEARCH AIM

In this study, we aimed to evaluate the potential of chondroitin sulfate, the most prominent class of glycosaminoglycans in human milk, to protect against bacterial infection in an intestinal in vitro model.

METHODS

T84 cell monolayers were treated with chondroitin sulfate and cell viability was assessed across a number of doses. Monolayers were then pretreated with chondroitin sulfate and subsequently challenged with E. coli invasion and translocation to evaluate any protective role of the compound against infection. Tight junction barrier function was assessed by transepithelial electrical resistance, and cytokine levels were evaluated.

RESULTS

Chondroitin sulfate at any dose up to 750 μg/ml was not associated with any statistically significant decrease in cell viability. Additionally, chondroitin sulfate at 750 μg/ml was associated with a 75% decrease in both bacterial invasion and translocation compared to control.

CONCLUSIONS

These data suggest chondroitin sulfate may protect against bacterial infection through a reduction in both invasion and translocation, importantly without attendant reduction in cell viability.

The protective effects of fecal microbiota transplantation in an experimental model of necrotizing enterocolitis

BACKGROUND

Necrotizing enterocolitis (NEC) is a serious disease that affects premature neonates, causing high mortality. In the search for new options of treatment it was investigated whether fecal microbiota transplantation (FMT) decreased the inflammatory response during NEC development in experimental model.

METHODS

Wistar rats were used and divided as follows: naïve, control (NEC induction), FMT-before (transplantation of microbiota before insult) and FMT-after (microbiota transplantation after insult). The microbiota transplantation was performed by administering a feces solution obtained from an adult donor rat. The induction of enterocolitis involves feeding by artificial formula, hypothermia, hypoxia and endotoxin administration. MPO activity, TNF-α, IL-1β and IL-6 levels, oxidative and nitrosative damage and the grade of intestinal mucosa lesion were analyzed.

RESULTS

The control group had a significant increase of inflammatory and oxidative parameters when compared to naive animals. Both FMT-before and after decreased all inflammatory and oxidative damage parameters when compared to control group. This was also true to the intestinal mucosa damage.

CONCLUSION

FMT administered just before or after NEC induction improved gut and systemic inflammation, and gut oxidative damage and intestinal injury.

Recent Potential Noninvasive Biomarkers in Necrotizing Enterocolitis

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

Interleukin-6 serum levels predict surgical intervention in infants with necrotizing enterocolitis

BACKGROUND

Symptoms at suspicion of necrotizing enterocolitis (NEC) are often nonspecific and several biomarkers have been evaluated for their discriminative power to both diagnose and predict the course from NEC suspicion to complicated disease requiring surgical intervention. Thus, we aimed to assess the utility of interleukin-6 (IL-6) to predict surgical intervention in infants suffering from NEC and, furthermore, to discriminate infants with starting NEC or late-onset sepsis (LOS).

METHODS

IL-6 serum levels at disease onset were retrospectively analyzed in 24 infants suffering from NEC as well as 16 neonates with LOS.

RESULTS

IL-6 serum levels at disease onset were significantly higher in infants suffering from NEC necessitating surgical intervention in the disease course compared to infants with medical NEC (5000 [785-5000] vs. 370 [78-4716] pg/ml, p = 0.0008) as well as gram-positive LOS (5000 [785-5000] vs. 84 [12-269] pg/ml, p = 0.0001). Infants suffering from gram-negative LOS exhibited elevated IL-6 serum levels at disease onset comparable to infants with surgical NEC (5000 [1919-5000] vs. 5000 [785-5000] pg/ml, p = 1.00).

CONCLUSION

The proinflammatory cytokine IL-6 appears to be a promising marker to distinguish surgical NEC from medical NEC at the onset of disease but cannot discriminate between surgical NEC and gram-negative LOS.

LEVEL OF EVIDENCE

II.

An update on biomarkers of necrotizing enterocolitis

Necrotizing enterocolitis (NEC) remains a devastating surgical emergency with high morbidity and mortality in preterm infants. Slow but steady progress has been made in past years searching for novel biomarkers of NEC, for both surveillance and diagnostic purposes. This review primarily focuses on recent discoveries: clinical applications of different categories of biomarkers for surveillance, early diagnosis, and predicting severity and prognosis; and understanding of pathophysiological mechanisms as a basis to rationalize the search for 'gut-associated specific biomarkers' of NEC. An important next step is to collaborate with our industrial partners to develop point-of-care tests, and to discover novel and gut-associated specific biomarkers that can be used for surveillance and early diagnosis of NEC in routine clinical settings.

Combination of plasma white blood cell count, platelet count and C-reactive protein level for identifying surgical necrotizing enterocolitis in preterm infants without pneumoperitoneum

PURPOSE

To evaluate whether plasma white blood cell count (WBC), platelet count (PLT), and C-reactive protein level (CRP) can be used to differentiate surgical necrotizing enterocolitis (NEC) from medical NEC.

METHODS

Preterm infants admitted between January 1, 2011 and July 31, 2015 were stratified by the need of surgery as surgical NEC (n = 41) and medical NEC (n = 43). The values of WBC, PLT and CRP were collected at time before NEC occurred (T₀), at onset of NEC (T₁) and when surgical assessment was required (T₂). Patients admitted between August 1, 2015 and March 1, 2018 (n = 53) were collected for further verification.

RESULTS

Variables identified in logistic regression analysis predicting surgical NEC were WBC and PLT at T₂ (WBC₂ and PLT₂). The predictive probability of surgery (P) could be calculated by the equation [Formula: see text]. The area under curve of P was 0.84 and the ideal cutoff value was 0.55, with sensitivity and specificity of 85 and 81%, respectively. This cutoff value got an sensitivity of 80% and specificity of 79% in the verification group.

CONCLUSION

Combination of WBC and PLT can effectively differentiate surgical NEC from medical NEC infants when surgical assessment was required.

Changing the paradigm of defining, detecting, and diagnosing NEC: Perspectives on Bell's stages and biomarkers for NEC

Better means to diagnose and define necrotizing enterocolitis are needed to guide clinical practice and research. Adequacy of Bell's staging system for clinical practice and clarity of cases used in NEC clinical datasets has been a topic of controversy for some time. This article provides reasons why a better global definition for NEC is needed and offers a simple alternative bedside definition for preterm NEC called the "Two out of Three" rule. Some argue that biomarkers may fill knowledge gaps and provide greater precision in defining relevant features of a clinical disease like NEC. NEC biomarkers include markers of inflammation, intestinal dysfunction, hematologic changes, and clinical features. Development and reporting of NEC biomarkers should be guided by the FDA's BEST Consensus resource, "Biomarkers, EndpointS, & other Tools" and consistently report metrics so that studies can be compared and results pooled. Current practice in the NICU would be enhanced by clinical tools that effectively inform the clinical team that a baby is at increasing risk of NEC. Ideally, these tools will incorporate both clinical information about the baby as well as molecular signals that are indicative of NEC. While meaningful biomarkers for NEC and clinical tools exist, translation into practice is mediocre.

Serum Markers of Necrotizing Enterocolitis: A Systematic Review

OBJECTIVE

The aim of the study was to systematically review the diagnostic utility of serum biomarkers for the diagnosis of necrotizing enterocolitis (NEC).

METHODS

We conducted an electronic and manual search of the available evidence. We included studies reporting data on the diagnostic accuracy of "serum" biomarkers for the diagnosis of NEC, available until January 2016.

RESULTS

We selected 22 studies from the 1296 articles retrieved. Only S100 A8/A9 protein and apolipoprotein-CII showed high sensitivity (100% and 96.4%, respectively) and specificity (90% and 95%, respectively) in the studies using Bell stage II NEC as target condition. High sensitivity and specificity were reported for interleukin-10 (100% and 90%), interleukin1-receptor antagonist (100% and 91.7%), intestinal fatty acid-binding protein (100% and 91%) and ischemia-modified albumin (94.7% and 92%), when tested to predict the evolution from definite to advanced NEC. Given the amount of uncertainty, the limited availability of data and heterogeneity among the populations in the different studies, we were unable to perform a meta-analysis. Major concerns about the applicability stemmed from the spectrum of patients enrolled and the inclusion of diseases different from Bell stage ≥2 NEC as target conditions.

CONCLUSIONS

We identified only few markers with good diagnostic accuracy and found an overall low quality of the studies on serum NEC biomarkers. In conclusion, data supporting their use are insufficient.

Biomarkers of necrotizing enterocolitis: a review of literature

Necrotizing enterocolitis (NEC) is among the most serious gastrointestinal emergency in very low birth weight (VLBW), extremely low birth weight (ELBW) and extremely low gestational age neonates (ELGAN), affecting 7-14% of these neonates. Despite extensive research, the underlying aetiology of NEC still remains blurred. Due to high mortality, morbidity and its delayed presentation, early detection of NEC is considered to be lifesaving. A number of biomarkers have been studied for early detection and prediction of severity of NEC but till date, no ideal marker has been discovered. Molecular techniques like proteomic and metabolomic have recently emerged in the field for the development of biomarkers for early detection and understanding the pathophysiology of NEC. We did literature search for identifying all biomarkers that have been used for the detection of NEC and, in this review article, we discuss these biomarkers along with the available current evidence.

Surgical necrotizing enterocolitis

Although currently available data are variable, it appears that the incidence of surgical necrotizing enterocolitis (NEC) has not decreased significantly over the past decade. Pneumoperitoneum and clinical deterioration despite maximal medical therapy remain the most common indications for operative treatment. Robust studies linking outcomes with specific indications for operation are lacking. Promising biomarkers for severe NEC include fecal calprotectin and S100A12; serum fatty acid-binding protein; and urine biomarkers. Recent advances in ultrasonography make this imaging modality more useful in identifying surgical NEC and near-infrared spectroscopy (NIRS) is being actively studied. Another fairly recent finding is that regionalization of care for infants with NEC likely improves outcomes. The neurodevelopmental outcomes after surgical treatment are known to be poor. A randomized trial near completion will provide robust data regarding neurodevelopmental outcomes after laparotomy versus drainage as the initial operative treatment for severe NEC.

Necrotizing enterocolitis symposium: Epidemiology and early diagnosis

Despite decades of research on necrotizing enterocolitis (NEC), the outlook for infants afflicted by this devastating disease is all too often bleak. The aim of this symposium at the BAPS conference in Amsterdam was to highlight recent advances in the knowledge of the epidemiology and diagnosis of NEC. There were important contributions on the disease in the United Kingdom, both from a neonatal and from a surgical point of view, whereas colleagues from the Netherlands and elsewhere in Europe shared their insights into novel diagnostic tools, both biofluid and imaging based.

LEVEL OF EVIDENCE

Level V.

Cytokines and growth factors in the developing intestine and during necrotizing enterocolitis

Cytokines and growth factors play diverse roles in the uninflamed fetal/neonatal intestinal mucosa and in the development of inflammatory bowel injury during necrotizing enterocolitis (NEC). During gestational development and the early neonatal period, the fetal/premature intestine is exposed to high levels of many "inflammatory" cytokines and growth factors, first via swallowed amniotic fluid in utero and then, after birth, in colostrum and mother's milk. This article reviews the dual, seemingly counter-intuitive roles of cytokines, where these agents play a "trophic" role and promote maturation of the uninflamed mucosa, but can also cause inflammation and promote intestinal injury during NEC.

Current Research on the Epidemiology, Pathogenesis, and Management of Necrotizing Enterocolitis

Despite decades of research on necrotizing enterocolitis, we still do not fully understand the pathogenesis of the disease, or how to prevent or how to treat it. However, as a result of recent significant advances in the microbiology, molecular biology, and cell biology of the intestine of preterm infants and infants with necrotizing enterocolitis, there is some hope that research into this devastating disease will yield some important translation into effective prevention, more rapid diagnosis, and novel therapies.

The immunological landscape in necrotising enterocolitis

Necrotising enterocolitis (NEC) is an uncommon, but devastating intestinal inflammatory disease that predominantly affects preterm infants. NEC is sometimes dubbed the spectre of neonatal intensive care units, as its onset is insidiously non-specific, and once the disease manifests, the damage inflicted on the baby's intestine is already disastrous. Subsequent sepsis and multi-organ failure entail a mortality of up to 65%. Development of effective treatments for NEC has stagnated, largely because of our lack of understanding of NEC pathogenesis. It is clear, however, that NEC is driven by a profoundly dysregulated immune system. NEC is associated with local increases in pro-inflammatory mediators, e.g. Toll-like receptor (TLR) 4, nuclear factor-κB, tumour necrosis factor, platelet-activating factor (PAF), interleukin (IL)-18, interferon-gamma, IL-6, IL-8 and IL-1β. Deficiencies in counter-regulatory mechanisms, including IL-1 receptor antagonist (IL-1Ra), TLR9, PAF-acetylhydrolase, transforming growth factor beta (TGF-β)_1&2, IL-10 and regulatory T cells likely facilitate a pro-inflammatory milieu in the NEC-afflicted intestine. There is insufficient evidence to conclude a predominance of an adaptive Th1-, Th2- or Th17-response in the disease. Our understanding of the accompanying regulation of systemic immunity remains poor; however, IL-1Ra, IL-6, IL-8 and TGF-β₁ show promise as biomarkers. Here, we chart the emerging immunological landscape that underpins NEC by reviewing the involvement and potential clinical implications of innate and adaptive immune mediators and their regulation in NEC.

Bloodstream infections during the onset of necrotizing enterocolitis and their relation with the pro-inflammatory response, gut wall integrity and severity of disease in NEC

INTRODUCTION

Bacterial involvement is believed to play a pivotal role in the development and disease outcome of NEC. However, whether a bloodstream infection (BSI) predisposes to NEC (e.g. by activating the pro-inflammatory response) or result from the loss of gut wall integrity during NEC development is a longstanding question.

OBJECTIVE

We hypothesize that the occurrence of a BSI plays a complementary role in the pathogenesis of NEC. The first aim of the study was to correlate the occurrence of a BSI during the early phase of NEC with intestinal fatty acid-binding protein (I-FABP) levels, as a marker for loss of gut wall integrity owing to mucosal damage, and Interleukin (IL)-8 levels, as a biomarker for the pro-inflammatory cascade in NEC. The second aim of the study was to investigate the relation between the occurrence of a BSI and disease outcome.

MATERIAL AND METHODS

We combined data from prospective trials from two large academic pediatric surgical centers. Thirty-eight neonates with NEC, 5 neonates with bacterial sepsis, and 14 controls were included.

RESULTS

BSIs occurred in 10/38 (26%) neonates at NEC onset. No association between the occurrence of BSIs and I-FABP levels in plasma (cohort 1: median 11ng/mL (range 0.8-298), cohort 2: median 6.8ng/mL (range 1.3-15)) was found in NEC patients (cohort 1: p=0.41; cohort 2: p=0.90). In addition, the occurrence of BSIs did not correlate with IL-8 (median 1562pg/mL (range 150-7,500); p=0.99). While the occurrence of a BSI was not correlated with Bell's stage (p=0.85), mortality was higher in patients with a BSI (p=0.005).

CONCLUSION

The low incidence of BSIs and the absent association of both the markers for loss of gut wall integrity and the pro-inflammatory response during the early phase of NEC, support the hypothesis that the presence of a BSI does not precede NEC.

Immunologic and Hematological Abnormalities in Necrotizing Enterocolitis

Necrotizing enterocolitis (NEC) is a leading cause of mortality in preterm infants. This article reviews the immunologic and hematological abnormalities typically seen in infants with NEC, such as elevated plasma cytokine levels, thrombocytopenia, increased or decreased neutrophil counts, low monocyte counts, and anemia. Some of these findings may provide important diagnostic and prognostic information.

Necrotizing enterocolitis: the mystery goes on

Necrotizing enterocolitis (NEC) has largely been present in neonatal intensive care units for the past 60 years. NEC prevalence has corresponded with the continued development and sophistication of neonatal intensive care. Despite major efforts towards its eradication, NEC has persisted and appears to be increasing in some centers. The pathophysiology of this disease remains poorly understood. Several issues have hampered our quest to develop a better understanding of this disease. These include the fact that what we have historically termed 'NEC' appears to be several different diseases. Animal models that are commonly used to study NEC pathophysiology and treatment do not directly reflect the most common form of the disease seen in human infants. The pathophysiology appears to be multifactorial, reflecting several different pathways to intestinal necrosis with different inciting factors. Spontaneous intestinal perforations, ischemic bowel disease secondary to cardiac anomalies as well as other entities that are clearly different from the most common form of NEC seen in preterm infants have been put into the same database. Here I describe some of the different forms of what has been called NEC and make some comments on its pathophysiology, where available studies suggest involvement of genetic factors, intestinal immaturity, hemodynamic instability, inflammation and a dysbiotic microbial ecology. Currently utilized approaches for the diagnosis of NEC are presented and innovative technologies for the development of diagnostic and predictive biomarkers are described. Predictions for future strategies are also discussed.