Necrotizing: A historical perspective

Time to full enteral feeds in hospitalised preterm and very low birth weight infants in Nigeria and Kenya

BACKGROUND

Preterm (born < 37 weeks' gestation) and very low birthweight (VLBW; <1.5kg) infants are at the greatest risk of morbidity and mortality within the first 28 days of life. Establishing full enteral feeds is a vital aspect of their clinical care. Evidence predominantly from high income countries shows that early and rapid advancement of feeds is safe and reduces length of hospital stay and adverse health outcomes. However, there are limited data on feeding practices and factors that influence the attainment of full enteral feeds among these vulnerable infants in sub-Saharan Africa.

AIM

To identify factors that influence the time to full enteral feeds, defined as tolerance of 120ml/kg/day, in hospitalised preterm and VLBW infants in neonatal units in two sub-Saharan African countries.

METHODS

Demographic and clinical variables were collected for newborns admitted to 7 neonatal units in Nigeria and Kenya over 6-months. Multiple linear regression analysis was conducted to identify factors independently associated with time to full enteral feeds.

RESULTS

Of the 2280 newborn infants admitted, 484 were preterm and VLBW. Overall, 222/484 (45.8%) infants died with over half of the deaths (136/222; 61.7%) occurring before the first feed. The median (inter-quartile range) time to first feed was 46 (27, 72) hours of life and time to full enteral feeds (tFEF) was 8 (4.5,12) days with marked variation between neonatal units. Independent predictors of tFEF were time to first feed (unstandardised coefficient B 1.69; 95% CI 1.11 to 2.26; p value <0.001), gestational age (1.77; 0.72 to 2.81; <0.001), the occurrence of respiratory distress (-1.89; -3.50 to -0.79; <0.002) and necrotising enterocolitis (4.31; 1.00 to 7.62; <0.011).

CONCLUSION

The use of standardised feeding guidelines may decrease variations in clinical practice, shorten tFEF and thereby improve preterm and VLBW outcomes.

Prophylactic indomethacin, antenatal betamethasone, and the risk of intestinal perforation in infants <28 weeks' gestation

OBJECTIVE

To determine if intestinal perforations before 14 days (either spontaneous (SIP) or necrotizing enterocolitis-induced) are increased when infants who received antenatal betamethasone shortly before birth are treated with prophylactic indomethacin (PINDO).

STUDY DESIGN

Observational study of 475 infants <28 week's gestation assigned to either a PINDO-protocol (n = 231) or expectant management protocol (n = 244) during consecutive protocol epochs.

RESULTS

Intestinal perforations before 14 days occurred in 33/475 (7%). In unadjusted and adjusted models, we found no associations between PINDO-protocol and intestinal perforations. PINDO-protocol did not increase intestinal perforations or SIP-alone even when given to infants who received betamethasone <7 or <2 days before delivery. 213/231 (92%) PINDO-protocol infants actually received indomethacin. The results were unchanged when examined just in those who received indomethacin.

CONCLUSION

In our study, early intestinal perforations and SIP-alone were not increased when PINDO was used by protocol in infants who received antenatal betamethasone shortly before birth.

Neurologic consequences of neonatal necrotizing enterocolitis

Necrotizing enterocolitis (NEC) is a severe gastrointestinal disease of the premature infant with high mortality and morbidity. Children who survive NEC have been shown to demonstrate neurodevelopmental delay, with significantly worse outcomes than from prematurity alone. The pathways leading to NEC-associated neurological impairments remain unclear, limiting the development of preventative and protective strategies. This review aims to summarize the existing clinical and experimental studies related to NEC-associated brain injury. We describe the current epidemiology of NEC, reported long-term neurodevelopmental outcomes among survivors, and proposed pathogenesis of brain injury in NEC. Highlighted are the potential connections between hypoxia-ischemia, nutrition, infection, gut inflammation, and the developing brain in NEC.

Prevention of Necrotizing Enterocolitis

Necrotizing enterocolitis (NEC) is considered to be one of the most devastating intestinal diseases seen in neonatal intensive care. Measures to treat NEC are often too late, and we need effective preventative measures to alleviate the burden of this disease. The purpose of this review is to summarize currently used measures, and those showing future promise for prevention.

Enteral Feeding and Necrotizing Enterocolitis: Does Time of First Feeds and Rate of Advancement Matter?

OBJECTIVE

The aim of the study was to determine if time to initial enteral feeding (EF) and rate of advancement are associated with necrotizing enterocolitis (NEC) or death.

METHODS

Secondary analysis of prospectively collected data of very-low-birth-weight infants (VLBWI: 400--1500 g) born in 26 NEOCOSUR centers between 2000 and 2014.

RESULTS

Among 12,387 VLBWI, 83.7% survived without NEC, 6.6% developed NEC and survived, and 9.6% had NEC and died or died without NEC (NEC/death). After risk adjustment, time to initial EF (median = 2 days) was not associated with NEC; however, delaying it was protective for NEC/death (odds ratio [OR] = 0.96; 95% confidence interval [CI] 0.93--0.99). A slower feeding advancement rate (FAR) was protective for NEC (OR = 0.97; 95% CI = 0.94-0.98) and for NEC/death (OR = 0.98; 95% CI = 0.96-0.99).

CONCLUSIONS

In VLBWI, there was no association between an early initial EF and NEC, although delaying it was associated with less NEC/death. A slower FAR was associated with lower risk of both outcomes.

A role for neonatal bacteremia in deaths due to intestinal perforation: spontaneous intestinal perforation compared with perforated necrotizing enterocolitis

OBJECTIVE

To examine the relationship between intestinal perforations (caused by either spontaneous perforation (SIP) or necrotizing enterocolitis (NEC)) and the outcome "death due to intestinal perforation".

METHODS

Multivariable logistic regression analyses were used to compare infants <28 weeks' gestation with SIP (n = 32) and perforated-NEC (n = 45) for the outcome perforation-related death.

RESULTS

In univariate analyses the incidence of death due to perforation was higher among infants with perforated-NEC (36%) than infants with SIP (13%). However, infants with perforated-NEC were more likely to be older than 10 days and have bacteremia/fungemia with non-coagulase-negative staphylococci (non-CONS) organisms than infants with SIP. After adjusting for confounding the only variable that was significantly associated with mortality due to perforation was the presence of non-CONS bacteremia/fungemia at the onset of perforation.

CONCLUSIONS

The apparent association between death and perforated-NEC could be explained by the higher incidence of non-CONS bacteremia/fungemia among infants with perforated-NEC.

Intestinal tract and parenteral multi-organ sequential pathological injury caused by necrotizing enterocolitis

BACKGROUND

To explore the relationship between the pathological changes of the colon, terminal ileum, lung, liver and kidney, and the changes of Bax, PCNA and PAF in a rat model of NEC.

METHODS

One hundred and forty neonatal SD rats were randomly divided into NEC group and control group (70 in each group). NEC group was given hypoxia, cold stimulation and artificial feeding twice a day for 3 consecutive days. The control group was only fed normally. After modeling, From the 1st day to the 7th day, 10 rats were sampled in each group for pathological examination of colon, terminal ileum, lung, liver and kidney tissue. The levels of Bax, PCNA and PAF were investigated by immunohistochemistry.

RESULTS

Compared with the normal group, in the NEC group, on the 1st day, the colon, terminal ileum, lung, liver and kidney showed inflammatory damage. On the 5th day, the inflammatory injury was reduced. The inflammation disappeared on the 7th day. There were differences in the time of apoptosis in the intestine. In the intestine, the proliferation of PCNA was weak at first and then strong. Bax in liver and kidney showed marked apoptosis and apoptosis time increased in the lung. The expression of PCNA increased in lung, liver and kidney, and the expression of PAF increased in lung and liver.

CONCLUSIONS

NEC can lead to secondary injury of different degrees in colon, terminal ileum, lung, liver and kidney, and the degree and time of injury and repair were different. In general, organ repair played a leading role on the 4th day after modeling.

Translational Advances in Pediatric Nutrition and Gastroenterology: New Insights from Pig Models

Pigs are increasingly important animals for modeling human pediatric nutrition and gastroenterology and complementing mechanistic studies in rodents. The comparative advantages in size and physiology of the neonatal pig have led to new translational and clinically relevant models of important diseases of the gastrointestinal tract and liver in premature infants. Studies in pigs have established the essential roles of prematurity, microbial colonization, and enteral nutrition in the pathogenesis of necrotizing enterocolitis. Studies in neonatal pigs have demonstrated the intestinal trophic effects of akey gut hormone, glucagon-like peptide 2 (GLP-2), and its role in the intestinal adaptation process and efficacy in the treatment of short bowel syndrome. Further, pigs have been instrumental in elucidating the physiology of parenteral nutrition-associated liver disease and the means by which phytosterols, fibroblast growth factor 19, and a new generation of lipid emulsions may modify disease. The premature pig will continue to be a valuable model in the development of optimal infant diets (donor human milk, colostrum), specific milk bioactives (arginine, growth factors), gut microbiota modifiers (pre-, pro-, and antibiotics), pharmaceutical drugs (GLP-2 analogs, FXR agonists), and novel diagnostic tools (near-infrared spectroscopy) to prevent and treat these pediatric diseases.

The emerging role of immunothrombosis in paediatric conditions

BACKGROUND

Immunothrombosis is a physiological process based on the release of neutrophil extracellular traps (NETs) to immobilise, contain and kill bacteria. This is an innate immune response in which the local activation of blood coagulation exerts the critical protective function during microbial infection. In recent years, there has been much interest in the adult literature about the key role of immunothrombosis in pathologic states including thrombosis, cancer, sepsis and trauma. Currently, little research has been done into its role in paediatric conditions.

METHODS

We conducted a literature search of the National Library of Medicine (MEDLINE/PubMed) from the years 2000 to May 2018 and qualitatively identified 24 relevant papers. References of articles included for full-text review were checked for relevant publications.

RESULTS

Our aim is to summarise the most relevant evidences regarding an excessive production or defective removal of NETs in paediatric conditions. In particular, we have divided the role of immunothrombosis into acute (sepsis, necrotising enterocolitis, otitis media, neonatal arterial ischaemic stroke, haemolytic anaemic diseases) and chronic (systemic lupus erythematous, type 1 diabetes mellitus, respiratory diseases, graft-versus-host disease) conditions to find important similarities in their pathophysiology.

CONCLUSION

The field of immunothrombosis in paediatric conditions is still in its infancy. We have presented multiple pathways of NET-induced disease together with possible areas of future research and treatments.

Oxidative stress assessment in intestine of newborn rats submitted to hypoxia and reoxygenation with tadalafil

Purpose:

To evaluate the functional and structural response of tadalafil effects in the intestinal mucosa, using an experimental model of hypoxia and reoxygenation injury in rats.

Methods:

The animals were divided into 4 groups: CTL, H/R, H/R+Td and M+Td. The newborn rats allocated in groups H/R, H/R+Td and M+Td were submitted twice a day, to a gas chamber with CO₂ at 100% for 10 minutes and afterward reoxygenation with O₂ at 98% for 10 minutes, in the three first days of life. Tadalafil dose was given to newborn of group H/R+Td and to the pregnant rat of group M+Td. Histological analysis was made with hematoxylin-eosin technique and oxidative stress through nitrite and nitrate levels and lipid peroxidation.

Results:

The histological analysis showed a reduction of mucosa alterations in the groups that received tadalafil. In the oxidative stress evaluation, occurred an increase of NO levels and less lipidic peroxidation in the ileum segments that received tadalafil.

Conclusion:

Tadalafil provides tissue protection when administered independently to both, pregnant or newborns.

Plasma miR-1290 Is a Novel and Specific Biomarker for Early Diagnosis of Necrotizing Enterocolitis-Biomarker Discovery with Prospective Cohort Evaluation

OBJECTIVE

To discover specific circulating microRNA (miRNA) biomarkers for the early differentiation of necrotizing enterocolitis (NEC) from neonatal sepsis and inflammatory conditions.

STUDY DESIGN

The study comprised 3 distinct phases: differential microarray analysis to compare plasma miRNA expression profiles of NEC vs sepsis and non-NEC/nonsepsis cases, a case-control study to quantify dysregulated miRNAs as potential specific biomarkers of NEC, and a prospective cohort study to assess the diagnostic usefulness of the best miRNA biomarker(s).

RESULTS

A distinct miRNA expression profile was observed in the NEC compared with the sepsis and non-NEC/nonsepsis groups. miR-1290, miR-1246, and miR-375 were discovered to be specific biomarkers of NEC in the case-control study. In the cohort study (n = 301), plasma miR-1290 (day 0; >220 copies/µL) provided the greatest diagnostic usefulness for identifying both mild medical and severe surgical NEC cases. Of 20 infants with miR-1290 >650 copies/µL, 15 were diagnosed with NEC. Incorporating C-reactive protein (day 1; >15.8 mg/L) for cases with intermediate levels (220-650 copies/µL) in a 2-stage algorithm further optimized the diagnostic profile with a sensitivity of 0.83, a specificity of 0.96, a positive predictive value of 0.75, and a negative predictive value of 0.98. Importantly, 7 of 36 infants with NEC (19.4%) could be diagnosed 7.8-32.2 hours earlier (median, 13.3 hours) using miR-1290.

CONCLUSIONS

Plasma miR-1290 is a novel and specific biomarker that can effectively differentiate NEC cases from neonatal sepsis. miR-1290 facilitates neonatologists to confidently and timely reach a decision for early transfer of sick infants with NEC from community-based hospitals to tertiary surgical centers.

Necrotizing enterocolitis comes in different forms: Historical perspectives and defining the disease

The specific cause of what is commonly referred to as necrotizing enterocolitis (NEC) disease has been elusive largely because it is becoming clear that this entity represents more than one disease with multifactorial pathogenic mechanisms. Furthermore, finding clear and consistent diagnostic biomarkers will be difficult until the different subsets of what we are calling this disease are better delineated. In this introductory chapter, we discuss different disease entities that are frequently termed "NEC" in the newborn infant. We hope this will set the stage for more focused research and development of preventative measures for at least the most common forms of this disease.

Necrotizing Enterocolitis in Moderate Preterm Infants

Necrotizing enterocolitis (NEC) is a devastating morbidity usually seen in preterm infants, with extremely preterm neonates (EPT ≤28 weeks) considered at highest risk. Moderately preterm infants (MPT 28-34 weeks) constitute a large percentage of NICU admissions. In our retrospective data analysis of NEC in a single regional perinatal center, NEC was observed in 10% of extremely EPT and 7% of MPT, but only 0.7% of late-preterm/term admissions. There was an inverse relationship between postnatal age at onset of NEC and gestational age at birth. Among MPT infants with NEC, maternal hypertensive disorders (29%) and small for gestational age (SGA-15%) were more common than in EPT infants (11.6 and 4.6%, resp.). Congenital gastrointestinal anomalies were common among late preterm/term infants with NEC. SGA MPT infants born to mothers with hypertensive disorders are particularly at risk and should be closely monitored for signs of NEC. Identifying risk factors specific to each gestational age may help clinicians to tailor interventions to prevent NEC.

Prematurity reduces citrulline-arginine-nitric oxide production and precedes the onset of necrotizing enterocolitis in piglets

Necrotizing enterocolitis (NEC) is associated with low plasma arginine and vascular dysfunction. It is not clear whether low intestinal citrulline production, the precursor for arginine synthesis, occurs before and thus predisposes to NEC or if it results from tissue damage. This study was designed to test the hypothesis that whole body rates of citrulline, arginine, and nitric oxide synthesis are low in premature pigs and that they precede NEC. Piglets delivered by cesarean section at 103 days [preterm (PT)], 110 days [near-term (NT)], or 114 days [full-term (FT)] of gestation were given total parenteral nutrition and after 2 days orogastrically fed infant formula for 42 h to induce NEC. Citrulline and arginine fluxes were determined before and during the feeding protocol. Gross macroscopic and histological NEC scores and plasma fatty acid binding protein (iFABP) concentration were determined as indicators of NEC. Intestinal gene expression for enzymes of the arginine pathway were quantitated. A lower ( P < 0.05) survival rate was observed for PT (8/27) than for NT (9/9) and FT pigs (11/11). PT pigs had higher macroscopic gross ( P < 0.05) and histological NEC ( P < 0.05) scores and iFABP concentration ( P < 0.05) than pigs of more advanced gestational age. PT pigs had lower citrulline production and arginine fluxes ( P < 0.05) throughout and a reduced gene expression in genes of the citrulline-arginine pathway. In summary, intestinal enzyme expression and whole body citrulline and arginine fluxes were reduced in PT pigs compared with animals of more advance gestational age and preceded the development of NEC. NEW & NOTEWORTHY Arginine supplementation prevents necrotizing enterocolitis (NEC), the most common gastrointestinal emergency of prematurity. Citrulline (precursor for arginine) production is reduced during NEC, and this is believed to be a consequence of intestinal damage. In a swine model of NEC, we show that intestinal gene expression of the enzymes for citrulline production and whole body citrulline and arginine fluxes are reduced and precede the onset of NEC in premature pigs. Reduced citrulline production during prematurity may be a predisposition to NEC.

Necrotizing Enterocolitis and Neurodevelopmental Outcome

Necrotizing enterocolitis is a serious complication of prematurity that is associated with an increased risk for adverse neurodevelopmental outcome secondary to a complex relationship between various morbidities that increase the risk for central nervous system injury. Affected infants are exposed to a variety of circulating cytokines known to be associated with white matter injury. These infants also have an increased risk of secondary blood stream infections and nutritional compromise.

The Free Radical Diseases of Prematurity: From Cellular Mechanisms to Bedside

During the perinatal period, free radicals (FRs) are involved in several physiological roles such as the cellular responses to noxia, the defense against infectious agents, the regulation of cellular signaling function, and the induction of a mitogenic response. However, the overproduction of FRs and the insufficiency of an antioxidant mechanism result in oxidative stress (OS) which represents a deleterious process and an important mediator of damage to the placenta and the developing fetus. After birth, OS can be magnified by other predisposing conditions such as hypoxia, hyperoxia, ischemia, hypoxia ischemia-reperfusion, inflammation, and high levels of nonprotein-bound iron. Newborns are particularly susceptible to OS and oxidative damage due to the increased generation of FRs and the lack of adequate antioxidant protection. This impairment of the oxidative balance has been thought to be the common factor of the so-called “free radical related diseases of prematurity,” including retinopathy of prematurity, bronchopulmonary dysplasia, intraventricular hemorrhage, periventricular leukomalacia, necrotizing enterocolitis, kidney damage, and oxidative hemolysis. In this review, we provide an update focused on the factors influencing these diseases refining the knowledge about the role of OS in their pathogenesis and the current evidences of such relationship. Mechanisms governing FR formation and subsequent OS may represent targets for counteracting tissue damage.

Enteric serotonin and oxytocin: endogenous regulation of severity in a murine model of necrotizing enterocolitis

Necrotizing enterocolitis (NEC), a gastrointestinal inflammatory disease of unknown etiology that may also affect the liver, causes a great deal of morbidity and mortality in premature infants. We tested the hypothesis that signaling molecules, which are endogenous to the bowel, regulate the severity of intestinal and hepatic damage in an established murine NEC model. Specifically, we postulated that mucosal serotonin (5-HT), which is proinflammatory, would exacerbate experimental NEC and that oxytocin (OT), which is present in enteric neurons and is anti-inflammatory, would oppose it. Genetic deletion of the 5-HT transporter (SERT), which increases and prolongs effects of 5-HT, was found to increase the severity of systemic manifestations, intestinal inflammation, and associated hepatotoxicity of experimental NEC. In contrast, genetic deletion of tryptophan hydroxylase 1 (TPH1), which is responsible for 5-HT biosynthesis in enterochromaffin (EC) cells of the intestinal mucosa, and TPH inhibition with LP-920540 both decrease the severity of experimental NEC in the small intestine and liver. These observations suggest that 5-HT from EC cells helps to drive the inflammatory damage to the gut and liver that occurs in the murine NEC model. Administration of OT decreased, while the OT receptor antagonist atosiban exacerbated, the intestinal inflammation of experimental NEC. Data from the current investigation are consistent with the tested hypotheses-that the enteric signaling molecules, 5-HT (positively) and OT (negatively) regulate severity of inflammation in a mouse model of NEC. Moreover, we suggest that mucosally restricted inhibition of 5-HT biosynthesis and/or administration of OT may be useful in the treatment of NEC.NEW & NOTEWORTHY Serotonin (5-HT) and oxytocin reciprocally regulate the severity of intestinal inflammation and hepatotoxicity in a murine model of necrotizing enterocolitis (NEC). Selective depletion of mucosal 5-HT through genetic deletion or inhibition of tryptophan hydroxylase-1 ameliorates, while deletion of the 5-HT uptake transporter, which increases 5-HT availability, exacerbates the severity of NEC. In contrast, oxytocin reduces, while the oxytocin receptor antagonist atosiban enhances, NEC severity. Peripheral tryptophan hydroxylase inhibition may be useful in treatment of NEC.

Reducing Incidence of Necrotizing Enterocolitis

Necrotizing enterocolitis (NEC) is a multifactorial disease that occurs when multiple risk factors and/or stressors overlap, leading to profound inflammation and intestinal injury. Due to its multifactorial nature, there has been much uncertainty in identifying clear strategies for prevention of NEC. Despite these obstacles, the incidence of NEC has gradually been decreasing over the past 10 years, in part due to quality improvement (QI) initiatives to prevent NEC. Current QI strategies primarily target the various predisposing conditions. This article reviews the evidence on which QI interventions to prevent NEC have been based and provides examples of successful QI interventions.