Necrotizing enterocolitis

Paneth cell ablation in the presence of Klebsiella pneumoniae induces necrotizing enterocolitis (NEC)-like injury in the small intestine of immature mice

Necrotizing enterocolitis (NEC) is a leading cause of morbidity and mortality in premature infants. During NEC pathogenesis, bacteria are able to penetrate innate immune defenses and invade the intestinal epithelial layer, causing subsequent inflammation and tissue necrosis. Normally, Paneth cells appear in the intestinal crypts during the first trimester of human pregnancy. Paneth cells constitute a major component of the innate immune system by producing multiple antimicrobial peptides and proinflammatory mediators. To better understand the possible role of Paneth cell disruption in NEC, we quantified the number of Paneth cells present in infants with NEC and found that they were significantly decreased compared with age-matched controls. We were able to model this loss in the intestine of postnatal day (P)14-P16 (immature) mice by treating them with the zinc chelator dithizone. Intestines from dithizone-treated animals retained approximately half the number of Paneth cells compared with controls. Furthermore, by combining dithizone treatment with exposure to Klebsiella pneumoniae, we were able to induce intestinal injury and inflammatory induction that resembles human NEC. Additionally, this novel Paneth cell ablation model produces NEC-like pathology that is consistent with other currently used animal models, but this technique is simpler to use, can be used in older animals that have been dam fed, and represents a novel line of investigation to study NEC pathogenesis and treatment.

Near-infrared spectroscopy measurement of abdominal tissue oxygenation is a useful indicator of intestinal blood flow and necrotizing enterocolitis in premature piglets

PURPOSE

A major objective of necrotizing enterocolitis (NEC) research is to devise a noninvasive method of early detection. We hypothesized that abdominal near-infrared spectroscopy (A-NIRS) readings will identify impending NEC in a large animal model.

METHODS

Piglets were prematurely delivered and received parenteral nutrition followed by enteral feedings. Serial A-NIRS readings were obtained for 5 days, and animals were monitored for NEC. Separately, A-NIRS readings were obtained in healthy piglets to validate the correlation of A-NIRS with splanchnic oxygen delivery.

RESULTS

Of 29 piglets, 3 developed NEC. Eleven piglets without NEC died prematurely. Fifteen piglets remained healthy, had normal histologic assessment of their intestines, and served as controls. Abdominal near-infrared spectroscopy readings within 12 hours of birth were significantly lower in animals that developed NEC compared with healthy littermates (4% vs 33%, P = .02). For all time-points measured, A-NIRS readings were significantly lower in the NEC group compared with controls (21% vs 55%, P < .001). Abdominal near-infrared spectroscopy readings correlated with both decreased pulse oximetry readings during apneic episodes (r = 0.96) and increased superior mesenteric artery flow in response to glucagon-like peptide 2 (r = 0.67).

CONCLUSION

Abdominal near-infrared spectroscopy is capable of detecting alterations in intestinal oxygenation and perfusion in neonatal piglets and may allow early detection of neonates at risk for NEC.

ω-3 fatty acids attenuate mucosal inflammation in premature rat pups

BACKGROUND

Necrotizing enterocolitis (NEC) is a devastating intestinal disease of premature infants. Although ω-3 fatty acids are known to have antiinflammatory effects, their effect against NEC remains unclear.

METHODS

Mother rats fed a soybean-based, docosahexaenoic acid (DHA)- or eicosapentaenoic acid (EPA)-enriched diet from days 7 to 20 of gestation were examined. On day 20, the rat pups were delivered by abdominal incision, their intestines were removed, and messenger RNA was extracted. A rat NEC model was used to confirm the effects of ω-3 fatty acids on the inflamed intestine (n = 20-28). The expression of inflammatory molecules was analyzed by real-time polymerase chain reaction (n = 11-14).

RESULTS

The concentrations of DHA and EPA in the intestine were significantly increased in the DHA and EPA groups (P < .01). The expression of the antiinflammatory prostaglandin E2 receptor EP3 was increased in the DHA (P < .05) and EPA groups (P < .01). In the NEC model, the reduced incidence of colitis was confirmed in the DHA and EPA groups. The expression of peroxisome proliferator-activated receptor γ was increased (P < .05), and the inhibitor of nuclear factor-κB α/β decreased in both the DHA (P < .01) and EPA groups (P < .05).

CONCLUSION

Our findings indicate that ω-3 fatty acids are beneficial for protecting the premature intestine from inflammation by regulating eicosanoid- and nuclear factor-κB-related metabolite expression.

Pentoxifylline in preterm neonates: a systematic review

Sepsis, necrotizing enterocolitis (NEC), and chronic lung disease (CLD) in preterm neonates are associated with significant mortality and morbidity, including long-term neurodevelopmental impairment and socioeconomic burden. Safe and effective drugs for the prevention and treatment of these conditions are urgently needed. Pentoxifylline, a synthetic theobromine derivative, is a non-steroidal immunomodulating agent with unique hemorrheologic effects which has been used in a range of infectious, vascular, and inflammatory conditions in adults and children. The unique properties of pentoxifylline explain its potential benefits in preterm neonates with sepsis, NEC, and CLD, conditions characterized by activation of the inflammatory cytokine cascade, free radical toxicity, and impaired microcirculation. Pentoxifylline has anti-inflammatory properties resulting from inhibition of erythrocyte phosphodiesterase. It lowers blood viscosity and improves microcirculation and tissue perfusion. As a phosphodiesterase inhibitor, pentoxifylline downregulates pro-inflammatory cytokines such as tumor necrosis factor-alpha, interleukin-6, and interferon-gamma. Methylxanthines, including caffeine, theophylline, and theobromine are relatively non-toxic drugs; of these, theobromine is the least toxic. Pentoxifylline-related significant adverse events are thus very rare. Unlike other methylxanthines, pentoxifylline does not have significant cardiac and bronchodilating effects at therapeutic doses. Although it is contraindicated in adults with recent cerebral hemorrhage due to its effect on platelets, red blood cells, and plasma fibrinogen levels, no significant adverse effects including thrombocytopenia and bleeding have been reported in critically ill preterm neonates with sepsis or NEC after treatment with pentoxifylline. Based on data from pilot randomized trials and observational studies, our systematic review suggests that pentoxifylline may reduce mortality and/or morbidity in preterm neonates with sepsis, NEC, and CLD. Results of experimental studies also indicate that pentoxifylline may potentially be beneficial in meconium aspiration syndrome and hypoxic ischemic encephalopathy. Given the substantial burden of sepsis, NEC, and CLD in high-risk preterm neonates, and the findings of this systematic review, pentoxifylline needs to be evaluated urgently as a preventative and therapeutic agent for these conditions in randomized controlled trials that can detect minimal clinically significant effect sizes. Further clinical and experimental studies are also necessary to evaluate whether pentoxifylline is safe and effective in meconium aspiration syndrome and hypoxic ischemic encephalopathy.

Deletion of the heparin-binding epidermal growth factor-like growth factor gene increases susceptibility to necrotizing enterocolitis

BACKGROUND

Necrotizing enterocolitis (NEC) is the leading surgical cause of death in premature infants. We have accumulated evidence supporting a role for heparin-binding epidermal growth factor (EGF)-like growth factor (HB-EGF) in protection of the intestines from NEC. The aim of the current study was to evaluate the effect of loss-of-function of endogenous HB-EGF on susceptibility to NEC.

METHODS

Neonatal HB-EGF((-/-)) knockout (KO) mice and their HB-EGF((+/+)) wild-type (WT) counterparts were exposed to experimental NEC. An additional group of HB-EGF KO pups were also exposed to NEC but had HB-EGF added to their formula. To examine gut barrier function, HB-EGF KO and WT pups received intragastric fluorescein isothiocyanate-labeled dextran (FITC dextran) under basal and stressed conditions, and serum FITC dextran levels were measured.

RESULTS

The WT mice had an incidence of NEC of 53%, whereas HB-EGF KO mice had a significantly increased incidence of NEC of 80% (P = .04). Importantly, administration of exogenous HB-EGF to HB-EGF KO pups significantly reduced the incidence of NEC to 45% (P = .04). Heparin-binding EGF KO mice had significantly increased intestinal permeability compared to WT mice under basal and stressed conditions.

CONCLUSIONS

Our results provide evidence that loss of the HB-EGF gene increases susceptibility to NEC and that administration of exogenous HB-EGF reverses this susceptibility.

Doppler sonographic findings in an experimental rabbit model of necrotizing enterocolitis

OBJECTIVE

The purpose of this study was to examine the clinical applicability of Doppler sonography by evaluating Doppler sonographic findings in an experimental rabbit model of necrotizing enterocolitis (NEC).

METHODS

Necrotizing enterocolitis was experimentally induced using a combination of endotoxin, hypoxia, and cold stress in 23 rabbits. Doppler sonography was performed to obtain the Doppler spectrum of the superior mesenteric artery. From the flow profile, the peak systolic velocity (PSV) and resistive index (RI) were calculated at 5 time sessions: initial and 1 to 2, 3 to 4, 5 to 6, and 20 to 24 hours. Animals were divided into 2 groups based on pathologic NEC scores (NEC-positive [NEC+] group versus NEC-negative [NEC-] group). Differences between the groups with regard to RI and PSV values were evaluated for each time session.

RESULTS

Comparison of RI and PSV values between the NEC+ and NEC- groups revealed a significant increase in the PSV in the NEC+ group during the 1- to 2-hour session (P = .0199). Comparison of RI and PSV differences revealed a significant increase in RI and PSV differences in the NEC+ group during the 1- to 2-hour session (P = .0095 and .0013, respectively). In the other time sessions, there was no difference between the groups.

CONCLUSIONS

The NEC+ group showed a significant increase in the PSV and RI during the 1- to 2-hour period.

Early enteral feeding in conservatively managed stage II necrotizing enterocolitis is associated with a reduced risk of catheter-related sepsis

AIMS

To compare the effect of fasting period duration on complication rates in neonates managed conservatively for necrotizing enterocolitis (NEC) Bell stage II.

METHODS

We conducted a multicenter study to analyze retrospectively multiple data collected by standardized questionnaire on all admissions for NEC between January 2000 and December 2006. NEC was staged using modified Bell criteria. We divided the conservatively managed neonates with NEC Bell stage II into two groups (those fasted for <5 days and those fasted for >5 days) and compared the complication rates.

RESULTS

Of the 47 conservatively managed neonates Bell stage II, 30 (64%) fasted for <5 days (range 1-4 days) and 17 (36%) for >5 days (range 6-16 days). There were no significant differences for any of the patient characteristics analyzed. One (3%) and four (24%) neonates, respectively, developed post-NEC bowel stricture. One (3%) and two neonates (12%) suffered NEC relapse. None and five (29%) neonates developed catheter-related sepsis.

CONCLUSION

Shorter fasting after NEC appears to lower morbidity after the acute phase of the disease. In particular, shorter-fasted neonates have significantly less catheter-related sepsis. We found no benefit in longer fasting.

Necrotizing enterocolitis in 20,822 infants: analysis of medical and surgical treatments

Necrotizing enterocolitis (NEC) is the most common gastrointestinal emergency of the neonate. Previous information about this disease has largely been gathered from limited series. We analyzed 13 years of the National Inpatient Sample (NIS) and 3 years of the Kids' Inpatient Database (KID; 1997, 2000, 2003) to generate the most comprehensive profile of outcomes to date of medically versus surgically treated NEC. We identified 20 822 infants with NEC, of whom 15,419 (74.1%) and 5403 (25.9%) were undergoing medical and surgical management, respectively. Overall, surgical patients had greater length of stay, total hospital charges, and mortality. Among infants dying during admission, there was no significant difference in length of stay or charges between the medical and surgical groups. These findings highlight the need for developing a clinically relevant risk stratification tool to identify NEC patients at high risk for death.

Necrotizing enterocolitis

Necrotizing enterocolitis (NEC) remains a major cause of neonatal morbidity and death. The pathophysiology is poorly understood. Prevailing evidence suggests that NEC is due to an inappropriate inflammatory response of the immature gut to some undefined insult. The mortality rate (15%-25%) for affected infants has not changed appreciably in 30 years. Many infants with NEC recover uneventfully with medical therapy and have long-term outcomes similar to unaffected infants of matched gestational age. Infants with progressive disease requiring surgical intervention suffer almost all of the mortality and morbidity. Of these, approximately 30%-40% will die of their disease and most of the remainder will develop long-term neurodevelopmental and gastrointestinal morbidity. Recent randomized trials suggest that the choice of operation does not influence patient outcome. Current work is focusing on developing a better understanding of the pathogenesis and improving means to identify which infants are at greatest risk of disease progression.

Is mortality rate influenced by the site of involvement in neonates undergoing laparotomy for necrotizing enterocolitis?

PURPOSE

The aim of the study was to evaluate the effect of disease site on the mortality rate of newborns with necrotizing enterocolitis (NEC) undergoing exploratory laparotomy.

METHODS

The study used prospective cohort of 141 consecutive newborns with NEC who underwent laparotomy from November 1991 to December 2005.

RESULTS

One hundred nineteen (84.4%) newborns were premature. Small for gestational age was observed in 57 (40.4%). Sixty-eight (48.2%) infants died. Bivariate analysis revealed that involvement of the jejunum and ileum was associated with high mortality rates (20 deaths; 76.9%; odds ratio [OR], 20; 95% confidence interval [CI], 4.6-96.3; P < .001) and that coinvolvement of the jejunum was associated with greater disease extent. After controlling for individual variables, logistic regression showed that the mortality associated with jejunum and ileum involvement (OR, 0.61; 95% CI, 0.06-6.14; P = .68) did not differ from that associated with large bowel involvement (OR, 2.91; 95% CI, 0.81-10.50; P = .10). When the jejunum was involved with the disease, the percentage of involvement of the entire intestine was 72%, and the mortality rate was 85.1%. When the other bowel segments were involved, the global percentage of disease extent ranged from 42% to 49%, and the mortality rate from 51.9% to 71.8%. After multivariable adjustment disease site, jejunal involvement appeared to be only a surrogate marker of disease extent.

CONCLUSIONS

The NEC-related mortality in newborns undergoing laparotomy was not influenced by disease site (small or large bowel). However, jejunum coinvolvement was a marker of greater disease extent and therefore of poor prognosis.

Stomal complications in the newborn with necrotizing enterocolitis

BACKGROUND

Infants who develop necrotizing enterocolitis (NEC) are usually managed with fecal diversion. The integrity of the bowel being diverted is often suboptimal. Our clinical impression is that stomas created in this circumstance are fraught with complications. The purpose of this study is to quantify the rate of these complications and identify risk factors.

METHODS

A retrospective data collection from May 1999 to May 2008 on infants undergoing laparotomy for NEC was conducted. Data collected included gestational age, birth weight, age, and weight at operation, indications for surgical therapy, procedure performed, time to stoma output, time to takedown of stoma, complication directly related to the ostomy, and mortality. Data comparisons were analyzed statistically using chi(2), Pearson's correlation, Fisher's exact test, or a 2-tailed Student's t-test with significance reported for P<0.05.

RESULTS

A total of 73 patients were identified. Mean gestational age was 28 (+/-4) wk, mean birth weight was 1247 (+/-713) g. Mean age at the time of surgery was 23 (+/-27) d, and mean weight at operation was 1513 (+/-1306) g. The most common indication for surgical intervention was pneumoperitoneum (n=43, 58%). The most common level of intestinal diversion was the ileum (n=63, 85%). In-house mortality was 13%. There were 31 patients (42%) who developed 32 stoma-related complications. Demographic or preoperative variables that were a significant predictor of stoma-related complications were gestational age (P=0.003) and preoperative weight (P=0.024).

CONCLUSION

Premature infants carry a risk for developing stoma-related complications. Within that cohort, there is significantly increased risk of stoma-related complications in patients who are younger in gestational age and who have low preoperative weight. Future prospective studies may allow insight into preventative practices.

Peculiaridades da circulação mesentérica em recém-nascidos e suas implicações em doenças gastrintestinais do período neonatal

OBJETIVO:Descrever peculiaridades da circulação mesentérica neonatal e caracterizar fatores de suscetibilidade ao desenvolvimento de doenças gastrintestinais e alterações do fluxo sanguíneo da artéria mesentérica superior por meio da dopplerfluxometria. FONTES DE DADOS: Livros-textos e publicações indexadas no Medline e SciELO nos últimos 20 anos, utilizando-se as palavras chaves: "mesenteric artery", "superior mesenteric artery", "newborn intestinal circulation", "necrotizing enterocolitis", "doppler flow velocimetry". SÍNTESE DOS DADOS: Alterações do fluxo sanguíneo mesentérico são um dos fatores predisponentes da enterocolite necrosante, doença neonatal de alta morbimortalidade que acomete principalmente prematuros. A circulação mesentérica é peculiar no período neonatal tanto em relação ao seu estado basal, quanto à sua resposta frente a estímulos fisiológicos. Variações da irrigação mesentérica podem ser inerentes à própria fase de desenvolvimento vascular intestinal do recém-nascido pré-termo, com possíveis agravos de fatores perinatais como: insuficiência placentária, asfixia, infecção, cateterismo umbilical, drogas (indometacina e cafeína), fototerapia, alimentação artificial e progressão rápida da dieta. A dopplerfluxometria permite o estudo da irrigação de órgãos-alvo e pode quantificar o fluxo sanguíneo, a resistência vascular e predizer situações de risco para doenças do trato gastrintestinal no período neonatal. CONCLUSÕES: O recém-nascido apresenta peculiaridades de irrigação sanguínea gastrintestinal. A dopplerfluxometria da artéria mesentérica superior é um método não invasivo que determina as condições circulatórias no território intestinal.

Heparin-binding EGF-like growth factor is a potent dilator of terminal mesenteric arterioles

OBJECTIVE

We have previously shown that heparin-binding EGF-like growth factor (HB-EGF) protects the intestines from multiple forms of injury via direct cytoprotective effects on the intestinal mucosa. In this study, we examined the effects of HB-EGF on the hemodynamics of intestinal arterioles, the major resistance vessels that regulate blood flow to the intestines, as an additional mechanism of HB-EGF-mediated intestinal protection.

METHODS

The hemodynamic effects of HB-EGF in rodent terminal mesenteric arterioles and human submucosal arterioles were examined ex vivo using a video dimension analyzer. Cultured human intestinal microvascular endothelial cells (HIMEC) were used to elucidate the mechanisms of HB-EGF-induced vasodilation.

RESULTS

HB-EGF significantly increased vessel diameter under conditions of increasing intraluminal pressure and increased flow rate. These HB-EGF-mediated vasodilatory effects were observed in terminal mesenteric arterioles from adult rats and 3 day old rat pups. These effects were confirmed in submucosal arterioles from human intestine. Furthermore, HB-EGF significantly reduced endothelin-1-induced mesenteric arteriolar vasoconstriction. The vasodilatory effects of HB-EGF were blocked by ET(B) receptor antagonism in adult rat arterioles, and also by nitric oxide synthase inhibition in rat pup and human infant arterioles. In HIMEC, HB-EGF significantly increased endothelin B (ET(B)) receptor protein expression and provoked intracellular calcium mobilization.

CONCLUSIONS

HB-EGF is a potent vasodilator of the intestinal microvasculature, further supporting its use in diseases manifested by decreased intestinal blood flow, including necrotizing enterocolitis.

Tissue-engineered small intestine and stomach form from autologous tissue in a preclinical large animal model

BACKGROUND

Tissue-engineered small intestine, stomach, large intestine, esophagus, and gastroesophageal (GE) junction have been successfully formed from syngeneic cells, and employed as a rescue therapy in a small animal model. The purpose of this study is to determine if engineered intestine and stomach could be generated in an autologous, preclinical large animal model, and to identify if the tissue-engineered intestine retained features of an intact stem cell niche.

METHODS

A short segment of jejunum or stomach was resected from 6-wk-old Yorkshire swine. Organoid units, multicellular clusters with predominantly epithelial content, were generated and loaded onto biodegradable scaffold tubes. The constructs were then implanted intraperitoneally in the autologous host. Seven wk later, all implants were harvested and analyzed using histology and immunohistochemistry techniques.

RESULTS

Autologous engineered small intestine and stomach formed. Tissue-engineered intestinal architecture replicated that of native intestine. Histology revealed tissue-engineered small intestinal mucosa composed of a columnar epithelium with all differentiated intestinal cell types adjacent to an innervated muscularis mucosae. Intestinal subepithelial myofibroblasts, specialized cells that participate in the stem cell niche formation, were identified. Moreover, cells positive for the putative intestinal stem cell marker, doublecortin and CaM kinase-like-1 (DCAMKL-1) expression were identified at the base of the crypts. Finally, tissue-engineered stomach also formed with antral-type mucosa (mucus cells and surface foveolar cells) and a muscularis.

CONCLUSION

We successfully generated tissue-engineered intestine with correct architecture, including features of an intact stem cell niche, in the pig model. To our knowledge, this is the first demonstration in which tissue-engineered intestine was successfully generated in an autologous manner in an animal model, which may better emulate a human host and the intended therapeutic pathway for humans.

Epidemiology of necrotizing enterocolitis temporal clustering in two neonatology practices

OBJECTIVE

To develop a statistical method for defining clusters of necrotizing enterocolitis (NEC) cases in the neonatal intensive care unit (NICU).

STUDY DESIGN

The study group included 2782 infants weighing 401 to 1500 g at birth born between 1996 and 2004. NEC was defined as Bell stage II or III. Two statistical methods were used to define "disease clusters": a modified scan test and a comparison of observed and expected incidence density rates (IDRs) of NEC at each NICU.

RESULTS

The proportion of infants with NEC was similar in the 2 NICUs (7.1% vs 7.7%; P = .6), as was the expected IDR of NEC (1.39/1000 patient-days vs 1.32/1000 patient-days; P = .72). Twelve temporal clusters of NEC were identified in the 2 NICUs, representing 18% of 203 total NEC cases during the study period. No seasonal/secular trends were noted for NEC rates or identified clusters. Potential NEC clusters of > or =3 cases at either NICU had a >75% likelihood of being a true NEC cluster.

CONCLUSIONS

No operational definition of NEC cluster exists. This study introduces methods to use in prospective surveillance and to guide studies investigating etiologic relevance. Using the proposed methods, statistically significant clusters (ie, potential outbreaks) of NEC within NICUs can be identified early, providing an opportunity for early implementation of cluster investigation protocols.

Preclinical neonatal rat studies of heparin-binding EGF-like growth factor in protection of the intestines from necrotizing enterocolitis

We have previously demonstrated that enterally administered heparin-binding EGF-like growth factor (HB-EGF) produced in Escherichia coli decreases the incidence and severity of intestinal injury in a neonatal rat model of necrotizing enterocolitis (NEC). In preparation for upcoming human clinical trials, large-scale production of HB-EGF according to Good Manufacturing Practice (GMP) has been successfully accomplished using a Pichia pastoris yeast system. The current studies used a neonatal rat model of NEC to elucidate several important preclinical characteristics of HB-EGF therapy. We found that enteral administration of HB-EGF (800 microg/kg/dose) four times a day effectively reduced the incidence and severity of NEC, that Pichia-derived HB-EGF was not significantly different from E. coli-derived HB-EGF in preventing NEC, that EGF was not superior to HB-EGF in preventing NEC, and that prophylactic administration of HB-EGF added to formula starting with the first feed or 12 h later significantly reduced the incidence of NEC, with no change in the incidence of NEC noted if HB-EGF was added to the formula starting 24, 48, or 72 h after birth. Thus, large-scale production of GMP-grade HB-EGF in Pichia pastoris yeast produces a biologically active molecule suitable for human clinical trials.

Current concepts regarding the pathogenesis of necrotizing enterocolitis

Necrotizing enterocolitis (NEC) is a devastating disease that predominantly affects premature neonates. The mortality associated with NEC has not changed appreciably over the past several decades. The underlying etiology of NEC remains elusive, although bacterial colonization of the gut, formula feeding, and perinatal stress have been implicated as putative risk factors. The disease is characterized by massive epithelial destruction, which results in gut barrier failure. The exact molecular and cellular mechanisms involved in this complex disease are poorly understood. Recent studies have provided significant insight into our understanding of the pathogenesis of NEC. Endogenous mediators such as prostanoids, cyclooxygenases, and nitric oxide may play a role in the development of gut barrier failure. Understanding the structural architecture of the gut barrier and the cellular mechanisms that are responsible for gut epithelial damage could lead to the development of novel diagnostic, prophylactic and therapeutic strategies in NEC.

Prenatal lipopolysaccharide increases postnatal intestinal injury in a rat model of necrotizing enterocolitis

BACKGROUND

An increased incidence of necrotizing enterocolitis (NEC) has been noted in infants who are born to mothers with chorioamnionitis.

HYPOTHESIS

Our objective was to test the hypothesis that newborn rat pups born to mothers exposed to prenatal lipopolysaccharide during pregnancy would be more susceptible to intestinal injury in a rat model of NEC and that the increased intestinal injury is mediated by dysregulation of inducible nitric oxide synthase.

METHODS

Time-dated pregnant Sprague-Dawley dams were given an intraperitoneal injection of either 2 mg/kg of lipopolysaccharide or vehicle. Rat pups from each group of dams were delivered at term and placed in a rat NEC model. A subset of pups was given either vehicle or aminoguanidine. Intestines were harvested and graded for degree of intestinal injury.

RESULTS

Maternal prenatal lipopolysaccharide exposure increased the frequency and severity of intestinal injury in the neonatal rat NEC model. Treatment with aminoguanidine significantly decreased plasma nitric oxide levels. Additionally, aminoguanidine significantly decreased intestinal injury.

CONCLUSIONS

Intestinal injury observed may be mediated via nitric oxide synthase dysregulation.

Necrotizing enterocolitis--bench to bedside: novel and emerging strategies

Necrotizing enterocolitis (NEC) is a devastating illness that predominantly affects premature neonates. The mortality associated with this disease has changed very little during the last two decades. Neonates with NEC fall into two categories: those who respond to medical management alone and those who require surgical treatment. The disease distribution may be focal, multifocal, or panintestinal. Surgical treatment should therefore be based on disease presentation. Recent studies have added significant insight into our understanding of the pathogenesis of NEC. Several groups have shown that upregulation of nitric oxide plays an integral role in the development of epithelial injury in NEC. As a result, some treatment strategies have been aimed at abrogating the toxic effects of nitric oxide. In addition, several investigators have reported the cytoprotective effect of epidermal growth factor, which is found in high levels in breast milk, on the intestinal epithelium. Thus, fortification of infant formula with specific growth factors could soon become a preferred strategy to accelerate intestinal maturation in the premature neonate to prevent the development of NEC. One of the most devastating complications of NEC is the development of short bowel syndrome (SBS). The current treatment of SBS involves intestinal lengthening procedures or bowel transplantation. A novel emerging method for treating SBS involves the use of tissue-engineered intestine. In laboratory animals, tissue-engineered small intestine has been shown to be successful in treating intestinal failure. This article examines recent data regarding surgical treatment options for NEC as well as emerging treatment modalities.

Lethal pneumatosis coli in a 12-month-old child caused by acute intestinal gas gangrene after prolonged artificial nutrition: a case report

INTRODUCTION

Pneumatosis coli is a rare disease with heterogeneous symptoms which can be detected in the course of various acute and chronic intestinal diseases in children, such as necrotizing enterocolitis, intestinal obstruction and intestinal bacteriological infections.

CASE PRESENTATION

We report the case of a 12-month-old boy who died of pneumatosis coli caused by an acute intestinal gas gangrene after prolonged artificial alimentation.

CONCLUSION

While intestinal gas gangrene is a highly uncommon cause of pneumatosis coli, it is important to consider it as a differential diagnosis, especially in patients receiving a prolonged artificial food supply. These patients may develop intestinal gas gangrene due to a dysfunctional intestinal barrier.

Protective effects of vitamin E and omeprazole on the hypoxia/reoxygenation induced intestinal injury in newborn rats

Evaluation of prophylactic effects of omeprazole and/or vitamin E on the formation of free oxygen radicals (FOR) and bowel histopathology in the newborn rat model of hypoxia/reoxygenation (H/R) that resembles human necrotizing enterocolitis (NEC). Eighty newborn rats were randomly divided into eight groups. H/R was done using airtight chamber. Rats were exposed to 100% CO2 for 15 min followed by a reoxygenation for the next 15 min with 100% O2. Group 1 (n = 10) was the control group. Group 2 (n = 10) rats received vitamin E. In Group 3 (n = 10) omeprazole was administrated. Group 4 (n = 10) rats received omeprazole and vitamin E. Group 5 (n = 10) rats were subjected to H/R two times for 2 days and one time for 3 days. Group 6 (n = 10) received vitamin E in addition to H/R for 5 days and in Group 7 (n = 10) omeprazole in addition to H/R for 5 days. In Group 8 (n = 10), vitamin E and omeprazole and H/R were applied for 5 days. Rats were killed at the end of the each process and bowel specimens were harvested for histopathological and biochemical investigations. We administrated vitamin E intramuscularly 300 unit/kg per day and omeprazole orally 20 mg/kg per day. Malondialdehyde (MDA), xanthine oxidase (XO), xanthine dehydogenase (XDH) and XO/(XO + XDH) were measured. Vitamin E and/or omeprazole treated rats had significantly less XO% levels than H/R only group (0.36, 0.38 and 0.57, respectively). Similarly, the MDA levels were significantly lower in vitamin E and/or omeprazole received rats than H/R only rats (88.8, 97.9 and 122.6, respectively). All rats treated with omeprazole and/or vitamin E had better biochemical and histopathological levels compared to H/R rats (p < 0.05). Histopathological results show that Group 5 (H/R only) had significantly more intestinal damage when compared with Group 6 (vitamin E + H/R), Group 7 (omeprazole + R/H) and Group 8 (vitamin E + omeprazole + H/R) (p < 0.001). Grade 2 and 3 intestinal damages were only in Group 5 and there were no statistical difference between in Groups 6, 7 and 8 (p > 0.001). Omeprazole and/or vitamin E may protect the biochemical and histopathological intestinal damage of H/R injury in rats. These drugs may be beneficial in the prophylaxis of NEC in humans as well.

Lactate dehydrogenase activity is increased in plasma of infants with advanced necrotizing enterocolitis

In infants with necrotizing enterocolitis (NEC), intestinal gangrene defines advanced disease. Since intestinal ischemia is considered a pathogenetic factor for intestinal gangrene, serum activity of mucosal and seromuscular enzymes may be elevated in these patients. Our aim was to evaluate if serum enzymes activity is increased in infants with NEC associated with intestinal gangrene. We performed a retrospective review of the case notes of infants operated on for NEC between 1998 and 2006. Patients with preoperative determination of serum enzymes were included in the study, and were divided into Group A and Group B based on the presence or absence of intestinal gangrene, respectively. Serum activities of alkaline phosphatase (ALP), glutamic oxaloacetic transaminase (GOT), creatine kinase (CK), and lactate dehydrogenase (LDH) were compared in the two Groups. Values are medians (interquartile range). Thirty-five infants were operated on for NEC in the study period. Eighteen patients fulfilled the inclusion criteria: 12 in Group A and six in Group B. Group A patients had significantly higher LDH activity [1131.0 (1092.0-1300.0) vs. 482.0 (440.0-624.5) IU/L; P < 0.005]. Our findings suggest that LDH activity may be increased in infants with NEC and intestinal gangrene. Its evaluation could be a further tool in the surgical decision making process in infants with NEC.

Neonatal necrotizing enterocolitis

Necrotizing enterocolitis (NEC) remains a major cause of morbidity and death in neonates. The 30% to 50% mortality rate for NEC with perforation has not changed appreciably in the past 30 years. The critical relevant outcomes following NEC include survival, gastrointestinal function, and neurodevelopmental status. In each of these areas, initial anecdotal and case-series analysis has been followed by studies using more sophisticated methods of analysis. The single most important predictor of outcome, besides gestational age, is whether or not the disease has progressed to the point requiring surgical intervention. Patients with NEC requiring operation have a high mortality. Moreover, the vast majority of morbidity following NEC occurs in the patients who survive following operation. The purpose of this review is to examine the evolution of evidence regarding outcomes for patients with NEC and to provide an update on our current state of knowledge.

Necrotizing enterocolitis

In necrotizing enterocolitis (NEC) the small (most often distal) and/or large bowel becomes injured, develops intramural air, and may progress to frank necrosis with perforation. Even with early, aggressive treatment, the progression of necrosis, which is highly characteristic of NEC, can lead to sepsis and death. This article reviews the current scientific knowledge related to the etiology and pathogenesis of NEC and discusses some possible preventive measures.

Dietary fat for infants with enterostomies

BACKGROUND/PURPOSE

Infants with enterostomies frequently have signs of short bowel syndrome. Our goal was to assess the effect of dietary lipids on ostomy output and weight gain in infants with enterostomies.

METHODS

We reviewed the medical records of 10 neonates with necrotizing enterocolitis or isolated intestinal perforations requiring temporary enterostomies. Infants had high stoma outputs and poor weight gain. All infants received a commercially available soluble dietary fat supplement added to their enteral feedings. Ostomy output as a percentage of enteral intake and daily weight gain were compared over 5-day intervals before and after adding the dietary fat.

RESULTS

We observed a decrease in ostomy output after the addition of dietary lipids to enteral feedings, from an average of 29.3% to 19.8% of dietary intake, a relative decrease of 32% (P < .05). Daily weight gain increased from an average of 7.7 g/d to 26.8 g/d (P < .01) after treatment initiation. Infants with the greatest ostomy output (>20% of dietary intake) benefited the most by adding the dietary fat.

CONCLUSIONS

Dietary lipids appear to decrease ostomy output and improve weight gain in infants with enterostomies and short bowel syndrome. The use of dietary lipids may be helpful in infants with enterostomies to limit the morbidity of this condition.

Effects of hyperoxia on postnatal intestinal development

Fetuses develop in a marked hypoxic environment in utero. Premature infants often require high concentrations of oxygen to survive and develop in an environment that would be considered an oxygen stress for the fetus. Postnatal hyperoxia alters organ development, but there is minimal research regarding the role of hyperoxia in intestinal development. We attempted to determine whether postnatal hyperoxia exposure alters intestinal growth and function by using a reliable, objective and sensitive set of methods to study region-specific postnatal intestinal maturation. Rat pups born naturally were placed in continual exposure to room air (normoxia) or 85% oxygen (hyperoxia) immediately after birth. Pups were sacrificed at 1 and 2 weeks of age. Intestines were removed and fixed in formalin. Average mucosal, submucosal, and muscularis thicknesses were measured on hematoxylin and eosin stained sections. Immunohistochemistry was performed using antibodies against NOS II. The staining intensity was determined and quantified for site-specific regions of intestinal sections. No differences in mucosal thickness, submucosal thickness, or muscularis thickness were measured in the duodenum, jejunum or colon at any age. At two weeks of age, the thickness of the ileal mucosa was significantly greater in the group reared in 85% oxygen, and the group exposed to room air demonstrated significantly greater NOS II protein concentration than the hyperoxia group within the distal villus, proximal villus/crypts, submucosa, and muscularis in the distal small intestine.

Comparaison entre le nombre et la nature des clostridium fécaux et d'autres facteurs de risque impliqués dans la pathologie intestinale des nouveau-nés

Cent quinze nouveau-nés, âgés de 31 jours au plus et hospitalisés dans deux unités de soins intensifs, ont été groupés en 6 classes d'après le diagnostic clinique (entérocolite avec ou sans examen anatomopathologique et avec ou sans pneumatose radiologique, ≪ colites hémorragiques ≫, diarrhée aiguë, absence de troubles digestifs). Le nombre total de bactéries cultivables et le nombre de Clostridium ont été déterminés dans leurs selles. Dans certaines selles, on a également recherché la présence de rota- et/ou de coronavirus. Les effectifs de nouveau-nés souffrant d'entérocolites, avec ou sans pneumatose, ou de colites hémorragiques dont les selles contiennent des Clostridium ne sont pas significativement différents de ceux des nouveau-nés sans trouble digestif, alors que les selles de nouveau-nés atteints de diarrhée aiguë contiennent moins fréquemment des Clostridium que celles des autres nouveaunés. Les Clostridium identifiés appartiennent aux espèces C. butyricum, C. perfringens, C. difficile, C. tertium et C. sordellii. L'analyse des correspondances comparant la variable classe de diagnostic à 23 autres variables suggère que les variables suivantes: gémellité, poids de naissance < 1900 g, âge gestationnel < 35 semaines, détresse respiratoire, pose d'un cathéter ombilical et nombre de Clostridium > 10⁷/g de selle à l'apparition des signes cliniques, soit entre le 8^e et le 12^e jour de vie, sont liées au diagnostic d'entérocolite avec pneumatose. A l'opposé, l'absence de gémellité, un poids de naissance et un âge gestationnel élevés, l'absence de troubles respiratoires, de cathétérisme ombilical et de Clostridium fécaux, l'apparition des premiers signes cliniques à un âge inférieur à 8 jours, mais la présence de rota- et/ou de coronavirus dans les selles, sont liés au diagnostic de diarrhée aiguë.

Mathematical modeling in necrotizing enterocolitis--a new look at an ongoing problem

Necrotizing enterocolitis (NEC) is the most common and lethal disease that affects the gastrointestinal (GI) tract of the premature infant. The etiology of NEC remains undefined. The only consistent epidemiological precursors for NEC are prematurity and enteral alimentation. Various inflammatory mediators, including tumor necrosis factor (TNF)-a, interleukin (IL)-1, IL-6, IL-8, IL-10, IL-18, platelet-activating factor (PAF), and nitric oxide (NO) have been implicated in the pathogenesis of NEC, but the kinetics and role of these agents are ill-defined. Currently, there are no biomarker predictors of NEC risk and severity. Sera or tissue from early time points in the development of the disease may help delineate early inflammatory events that predispose an individual to NEC, thus providing an interventional opportunity. We suggest that the lack of diagnostic and therapeutic modalities for NEC are due to the absence of a systems view of the disease, which in turn is hindered by a lack of sensitive physiological measurements that predict perturbations in the intestinal tissue compartment and an inability to reliably test serial samples for the presence of inflammatory mediators in small volumes and in a high-throughput manner. Computational modeling is a useful tool in the study of complex systems such as the inflammatory process. Computation models provide an "existence proof" for a given mechanism, uncover subtle inconsistencies between the underlying hypotheses and quantitative data, and force one to ask how much is known. We suggest that a properly validated and calibrated mathematical model of inflammation and its pathologic consequences in NEC will be useful for predicting the physiologic and biologic response in infants suffering from the disease.

Gastrointestinal development and meeting the nutritional needs of premature infants

The fear of necrotizing enterocolitis and feeding intolerance are major factors inhibiting the use of the enteral route as the primary means of nourishing premature infants. Parenteral nutrition may help to meet many of the nutritional needs of these infants, but has significant detrimental side effects that include intestinal atrophy, sepsis, and increased susceptibility to inflammatory stimuli and systemic inflammatory responses. Being able to minimize the use of the parenteral route and still maintain appropriate nutrition safely would be a major advance in neonatology. At the basis of our inability to use the enteral route is a poorly understood immature gastrointestinal tract. Approaches such as minimal enteral nutrition or trophic feedings may partially alleviate these problems. However, if we are to progress in greater utilization of the gastrointestinal tract, other factors need to be considered. These include the macronutrient composition of minimal enteral or trophic feedings and the microecology of the intestinal lumen. Some of the developmental aspects of the intestine, which include intestinal growth, motor activity, barrier and other innate immune functions, and the microecology of the developing intestine, are briefly reviewed here. The purpose of this review is to suggest important areas of future research in neonatal and developmental gastroenterology that could affect several conditions that are related to immaturity of the gastrointestinal tract.

Necrotizing enterocolitis: a practical guide to its prevention and management

Neonatal necrotizing enterocolitis is the second most common cause of morbidity in premature infants and requires intensive care over an extended period. Despite advances in medical and surgical techniques, the mortality and long-term morbidity due to necrotizing enterocolitis remain very high. Recent advances have shifted the attention of researchers from the classic triad (ischemia, bacteria, and the introduction of a metabolic substrate into the intestine) of necrotizing enterocolitis, to gut maturation, feeding practices, and inflammation. The focus on inflammation includes proinflammatory cytokines such as tumor necrosis factor-alpha, interleukin (IL)-6, IL-18, and platelet-activating factor. Research related to the etiology of necrotizing enterocolitis has moved quickly from clostridial toxin to bacterial and other infectious agents. More recently, the pattern of bacterial colonization has been given emphasis rather than the particular species or strain of bacteria or their virulence. Gram-negative bacteria that form part of the normal flora are now speculated as important factors in triggering the injury process in a setting where there is a severe paucity of bacterial species and possible lack of protective Gram-positive organisms. Although the incidence of necrotizing enterocolitis has increased because of the survival of low birthweight infants, clinicians are more vigilant in their detection of the early gastrointestinal symptoms of necrotizing enterocolitis; however, radiographic demonstration of pneumatosis intestinalis remains the hallmark of necrotizing enterocolitis. With prompt diagnosis, a large proportion of infants with necrotizing enterocolitis are now able to be managed medically with intravenous fluid and nutrition, nasogastric suction, antibacterials, and close monitoring of physiologic parameters. In the advanced cases that require surgery, clinicians tend to opt for either simple peritoneal drainage (for very small and sick infants) or laparotomy and resection of the affected part. Intestinal transplantation later in life is available as a viable option for those who undergo resection of large segments of the intestine. It is becoming more evident that treatment of this devastating disease is expensive and comes with the toll of significant long-term sequelae. This has resulted in renewed interest in designing alternative strategies to prevent this serious gastrointestinal disease. Simple trophic feeding and the use of L-glutamine and arginine are novel avenues that have been examined. The use of probiotics ('friendly' bacterial flora) has been introduced as a promising tool for establishing healthy bacterial flora in the newborn gut to block the injury process that may ultimately lead to necrotizing enterocolitis.

Intestinal trefoil factor in treatment of neonatal necrotizing enterocolitis in the rat model

AIM

Neonatal necrotizing enterocolitis (NEC) is the most common gastrointestinal disease of premature infants. The role of cytokines and growth factors in the pathophysiology of NEC is not yet clearly defined. Among these factors, the intestinal trefoil factor (ITF) is known as cytoprotective to the gut. We studied the cytoprotective effect of trefoil factor in the 1-day-old Wistar rat pup model following hypoxic-ischemic cold stress.

MATERIALS AND METHODS

In the present study, thirty 1-day-old Wistar rat pups were randomly divided into three groups: Group 1, normal controls: Group 2, NEC; Group 3, NEC+ITF. Experimental NEC was induced by exposure to hypoxia for 60 s followed by cold stress at 4 degrees C for 10 min. The animals were euthanized at development of NEC, and at 96 h the intestinal tissue was processed and examined for histological changes of NEC.

RESULTS

The pathological lesions indicated severe separation of the submucosa and lamina propria and tissue necrosis in Group 2, and slight submucosal and lamina propria separation in Group 3. There were no histopathological changes in the controls. The mean of histological grade of group 2 was 2.8 (range 2-4), and 1.2 (range 0-2) in group 3. A difference was found when the two groups were compared (P<0.05).

CONCLUSION

ITF may provide a new way for the therapy of NEC in rats.

Prevention of necrotizing enterocolitis in preterm infants: a 20-year experience

OBJECTIVE

Diet, indomethacin, and early use of dexamethasone have been implicated as possible causes of necrotizing enterocolitis and intestinal perforation. Because we seldom prescribe indomethacin or early dexamethasone therapy and we follow a special dietary regimen that provides late-onset, slow, continuous drip enteral feeding, we reviewed our 20 years of experience for the incidence of necrotizing enterocolitis and bowel perforation.

METHODS

We reviewed data on all 1239 very low birth weight infants (501-1500 g) admitted to our level III unit over a period of 20 years (1986-2005), for morphologic parameters, necrotizing enterocolitis, bowel perforation, use of the late-onset, slow, continuous drip protocol, and indomethacin therapy. Outcome data were also compared with Vermont Oxford Network data for the last 4 years.

RESULTS

In 20 years, 1158 infants received the late-onset, slow, continuous drip feeding protocol (group I), whereas 81 infants had either a change in dietary regimen, use of indomethacin, or early use of dexamethasone (group II). The rate of necrotizing enterocolitis in group I of 0.4% was significantly lower than that in group II of 6%. Group I, in comparison with the Vermont Oxford Network, had significantly lower rates of necrotizing enterocolitis (0.4% vs 5.9%), surgical necrotizing enterocolitis (0.4% vs 3.1%), and bowel perforation (0.35% vs 2.2%).

CONCLUSIONS

Our 20-year experience with 1239 very low birth weight infants suggests strongly that the late-onset, slow, continuous drip feeding protocol and avoidance of indomethacin and early dexamethasone treatment contribute to the prevention of necrotizing enterocolitis.

Role of micro-organisms in necrotizing enterocolitis

The frequency with which necrotizing enterocolitis occurs in outbreaks makes it likely that the illness can have an infective origin. Immunological and non-immunological defences of the gastrointestinal are impaired in early life. Consequently the gut of the preterm infant is predisposed to bacterial overgrowth. A wide range of pathogenic bacteria and viruses have been isolated from infants with necrotizing enterocolitis or detected histologically. The presence of bacterial metabolites in the breath, intestinal bullae (hydrogen) and urine (D-lactate) during the course of the illness is further confirmatory evidence. The presence of bacteria or bacterial products (such as exo- and endotoxin) in the circulation will lead to ischaemia of the intestine and other organs either directly or via mediators such as cytokines or platelet activating factor. Future studies in necrotizing enterocolitis should be directed to understanding and modulating inflammatory mediators in necrotizing enterocolitis and preventing the disease with breast milk and nutritional supplements (glutamine, short chain fatty acids), chemoprophylaxis, and antibodies.

The epidemiology and pathogenesis of necrotizing enterocolitis

Necrotizing enterocolitis (NEC), a syndrome characterized by crepitant necrosis of the bowel, has emerged as the most common neonatal gastrointestinal emergency in many countries of the world. In the United States, NEC strikes 1 to 8% of patients admitted to neonatal intensive care units, almost all of whom are premature infants. The incidence is low in certain countries wity a low premature birth rate, e.g., Japan. Two theories of pathogenesis are: the Santulli theory, which implicates three factors: ischaemia, bacteria and substrate; and the Lawrence theory, which stresses the injurious role of bacterial toxins on the immature gut of the preterm infant. Clinical and experimental evidence support each of the theories, but neither theory can explain certain clinical phenomena, particularly the resistance to NEC manifested by more than 90% of preterm infants, who never develop the syndrome. A unifying hypothesis of pathogenesis and a mathematical model of NEC are outlined. Because clustering of cases may occur, the design of clinical trials of preventive measures for NEC must include simultaneous control infants.

Toward improving mucosal barrier defenses: rhG-CSF plus IgG antibody

Epithelial cell functions ultimately define the ability of the extremely low birth weight human fetus to survive outside of the uterus. These specialized epithelial cell capacities manage all human interactions with the ex utero world including: (i) lung mechanics, surface chemistry and gas exchange, (ii) renal tubular balance of fluid and electrolytes, (iii) barrier functions of the intestine and skin for keeping bacteria out and water in, plus enabling intestinal digestion, as well as (iv) maintaining an intact neuroepithelium lining of the ventricles of the brain and retina. In Part I of this two part review, the authors describe why the gut barrier is a clinically relevant model system for studying the complex interplay between innate and adaptive immunity, dendritic &epithelial cell interactions, intraepithelial lymphocytes, M-cells, as well as the gut associated lymphoid tissues where colonization after birth, clinician feeding practices, use of antibiotics as well as exposure to prebiotics, probiotics and maternal vaginal flora all program the neonate for a life-time of immune competence distinguishing "self" from foreign antigens. These barrier defense capacities become destructive during disease processes like necrotizing enterocolitis (NEC) when an otherwise maturationally normal, yet dysregulated and immature, immune defense system is associated with high levels of certain inflammatory mediators like TNFa. In Part II the authors discuss the rationale for why rhG-CSF has theoretical advantages in managing NEC or sepsis by augmenting neonatal neutrophil number, neutrophil expression of Fcg and complement receptors, as well as phagocytic function and oxidative burst. rhG-CSF also has potent anti-TNFa functions that may serve to limit extension of tissue destruction while not impairing bacterial killing capacity. Healthy, non-infected neutropenic and septic neonates differ in their ability to respond to rhG-CSF; however, no neonatal clinical trials to date have identified a clear clinical benefit of rhG-CSF therapy. This manuscript will review the literature and evidence available for identifying the ideal subject for cytokine treatment using NEC as the model disease target.

Addressing the "New" NEC: Part I: rediscovering the basics

Epithelial cell functions ultimately define the ability of the extremely low birth weight human fetus to survive outside of the uterus. These specialized epithelial cell capacities manage all human interactions with the ex utero world including: (i) lung mechanics, surface chemistry and gas exchange, (ii) renal tubular balance of fluid and electrolytes, (iii) barrier functions of the intestine and skin for keeping bacteria out and water in, plus enabling intestinal digestion, as well as (iv) maintaining an intact neuroepithelium lining of the ventricles of the brain and retina. In Part I of this two part review, the authors describe why the gut barrier is a clinically relevant model system for studying the complex interplay between innate and adaptive immunity, dendritic &epithelial cell interactions, intraepithelial lymphocytes, M-cells, as well as the gut associated lymphoid tissues where colonization after birth, clinician feeding practices, use of antibiotics as well as exposure to prebiotics, probiotics and maternal vaginal flora all program the neonate for a life-time of immune competence distinguishing "self" from foreign antigens. These barrier defense capacities become destructive during disease processes like necrotizing enterocolitis (NEC) when an otherwise maturationally normal, yet dysregulated and immature, immune defense system is associated with high levels of certain inflammatory mediators like TNFa. In Part II, the authors will discuss the theoretical advantages of using rhG-CSF in managing NEC or sepsis by augmenting neonatal neutrophil number and killing capacity including an unexpected, paradoxical and potent anti-TNFa function that may serve to limit extension of tissue destruction without impairing bacterial killing capacity. The authors conclude by arguing that NEC may be the ideal disease process for testing whether a clearly defined clinical benefit of cytokine therapy can prove beneficial.

IL-1beta alters hemodynamics in newborn intestine: role of endothelin

Studies were carried out to determine the effects of IL-1beta on newborn intestinal hemodynamics. IL-1beta increased the release of ET-1 by primary endothelial cells in a dose-dependent manner; as well, it reduced expression of the endothelin (ET) type B (ET(B)) receptor on endothelial cells and increased expression of the ET type A (ET(A)) receptor on vascular smooth muscle cells. IL-1beta increased endothelial cell endothelial nitric oxide (NO) synthase (eNOS) expression but did not enhance eNOS activity as evidenced by release of NO(x) into conditioned medium in response to acetylcholine or shear stress. The effects of IL-1beta on flow-induced dilation were evaluated in terminal mesenteric arteries in vitro. Pretreatment with IL-1beta (1 ng; 4 h) significantly attenuated vasodilation in response to flow rates of 100 and 200 microl/min. This effect was mediated, in part, by the endothelin ET(A) receptor; thus selective blockade of ET(A) receptors with BQ610 nearly restored flow-induced dilation. In contrast, exogenous ET-1 only shifted the diameter-flow curve downward without altering the percent vasodilation in response to flow. The effects of IL-1beta on ileal oxygenation were then studied using in vivo gut loops. Intramesenteric artery infusion of IL-1beta upstream of the gut loop caused ileal vasoconstriction and reduced the arterial-venous O(2) difference across the gut loop; consequently, it reduced ileal oxygenation by 60%. This effect was significantly attenuated by pretreatment with BQ610. These data support a linkage between the proinflammatory cytokine IL-1beta and vascular dysfunction within the intestinal circulation, mediated, at least in part, by the ET system.

Protective effects of recombinant human granulocyte colony stimulating factor in a rat model of necrotizing enterocolitis

The role of cytokines and growth factors in the pathophysiology of neonatal necrotizing enterocolitis (NEC) is not defined clearly yet. The aim of this study was to determine the effects of recombinant human granulocyte colony stimulating factor (G-CSF) on intestinal cells in hypoxia-induced experimental NEC in rats. The study was experimented on Sprague Dawley rat pups. Group 1 (untreated, n = 7) rats were subjected to hypoxia-reoxygenation (H/O) and then were returned to standard conditions. Group 2 (G-CSF treated, n = 7) rats were subjected to H/O, and then were treated with G-CSF (100 microg/kg enterally) for 5 days. Group 3 was served as nonhypoxic controls. All animals were killed on day five, and histological examination was performed on intestinal samples. There were no histopathological changes in the control group. The histological findings in untreated rats were similar to those seen in neonatal NEC, with destruction of villi and crypts with extension to the muscularis layer. Intestinal damage was mild in group 2 and these histological changes were better than group 1, and worse than group 3. The mean of histologic grade of group 1 was 2.4 (range 2-3), and in the group 2, it was 1.2 (range 0-2). A difference was found when two groups were compared with each other (P < 0.05). In an experimental model of NEC, G-CSF could have a protective effect on intestinal damage.

Pentoxifylline reduces the incidence and severity of necrotizing enterocolitis in a neonatal rat model

Necrotizing enterocolitis (NEC) is a potentially fatal illness in premature neonates. Tumor necrosis factor alpha (TNF-alpha) has been shown to play a central role in the inflammatory cascade leading to the development of NEC. Published evidence points to a significant role of pentoxifylline in inhibition of TNF-alpha and in reducing mucosal injury and improving healing in ischemia-reperfusion experiments. Our aim was to investigate the effect of pentoxifylline on the incidence of NEC in a neonatal rat model. Newborn Sprague-Dawley rat pups originating from eight separate litters were delivered by cesarean section at 21.5 d and were formula fed from birth by orogastric gavage. The rat pups were randomized to receive either intraperitoneal pentoxifylline (15 mg/kg/dose) or placebo, given every 8 h beginning at 24 h of age, in a blinded fashion. Experimental NEC was induced by exposure to hypoxia for 60 s followed by cold stress at 4 degrees C for 10 min. The animals were euthanized at development of NEC or at 96 h and intestinal tissue was processed and examined for histologic changes of NEC. The incidence of NEC was significantly lower in the pentoxifylline group [pentoxifylline 5/38 versus placebo 15/36; p = 0.008, odds ratio (OR) = 0.21 95% confidence interval (CI) 0.07-0.67]. Among the pups developing NEC, significantly fewer rat pups treated with pentoxifylline had severe (>or=3) intestinal injury scores [pentoxifylline 1/5 versus placebo 10/15; p = 0.031, OR 0.06, 95% CI 0.01-0.79]. We conclude that intraperitoneal administration of pentoxifylline significantly reduced the incidence and severity of NEC in our experimental animal model.

Enteral granulocyte colony-stimulating factor for the treatment of mild (stage I) necrotizing enterocolitis: a placebo-controlled pilot study

BACKGROUND/PURPOSE

The presence of granulocyte colony-stimulating factor (G-CSF) in human milk and the expression of G-CSF receptors on intestinal villous enterocytes of neonates suggest that G-CSF has a role in the development and integrity of the gastrointestinal tract. We hypothesized that enteral recombinant human G-CSF (rhG-CSF) given to preterm infants with necrotizing enterocolitis (NEC) in the earlier stages could protect against disease progression and complications.

METHODS

Preterm infants with mild (stage I) NEC (n = 18) were assigned to receive enteral rhG-CSF (n = 8) or placebo (n = 10) for 5 days from the first day of the diagnosis. Clinical and gastrointestinal parameters were followed during the whole period of hospitalization.

RESULTS

In the study group, none of the infants with stage I NEC had a clinical progression to stage II or III, whereas in the control group, 5 (50%) infants with stage I NEC had a disease progression to stage II or III (P < .05). In the study group, the time required for the resolution of clinical and radiological findings of NEC and the total duration of systemic therapy and hospitalization were significantly shorter than the control group (P < .001).

CONCLUSION

Enteral rhG-CSF treatment could prevent the progression of mild (stage I) NEC to further stages and decrease the time required for the resolution of clinical and radiological signs of the disease.