Serum cytosolic beta-glucosidase activity in a rat model of necrotizing enterocolitis

Emerging prediction methods for early diagnosis of necrotizing enterocolitis

Necrotizing enterocolitis (NEC) is a life-threatening disease of the digestive system that occurs in the neonatal period. NEC is difficult to diagnose early and the prognosis is poor. Previous studies have reported that abnormalities can be detected before the presentation of clinical symptoms. Based on an analysis of literature related to the early prediction of NEC, we provide a detailed review on the early prediction and diagnosis methods of NEC, including ultrasound, near-infrared spectroscopy, biomarkers, and intestinal microbiota. This review aimed to provide a reference for further research and clinical practice.

Role of the antioxidant pathway in the healing of peptic ulcers induced by ischemia-reperfusion in male and female rats treated with Eugenia punicifolia

Ischaemia and reperfusion (I/R)-induced gastrointestinal disorders are caused by free radicals, resulting in organ damage and functional disarrangement. This study aimed to investigate the healing effects of hydroalcoholic extracts from the leaves of Eugenia punicifolia (Kunth) DC. (HEEP) in male and female Wistar rats with I/R-induced peptic injuries, and the role of antioxidants in improving this response. After I/R-induced gastric and duodenal injuries, male and female [intact (INT) and ovariectomized (OVZ)] rats were orally treated with HEEP for 6 days. Biochemical analysis was used to determine the catalase (CAT), superoxide dismutase (SOD), and myeloperoxidase (MPO) activities, as well as malondialdehyde and reduced glutathione levels, to measure the gastric and duodenal healing process. Six days of HEEP treatment significantly decreased the I/R-induced gastric [male (73.68%), INT (52.83%), and OVZ (43.13%)] and duodenal damage [male (57.03%), INT (56.04%), and OVZ (54.83%)] in all groups. In OVZ rats, the healing effect of HEEP occurred because of the increased activity of SOD (2x) and CAT (1.16x) in the gastric mucosa. In the duodenal mucosa of INT rats, the extract reduced MPO (20.83%) activity. The 6-day HEEP treatment improved the healing of I/R-induced peptic ulcer injury, with the system acting differently in males and females. The antioxidant system is an important component of the HEEP activity during post-I/R mucosal recovery. This result revealed the importance of antioxidant compounds in minimizing the severity of I/R-related events.

Animal models of necrotizing enterocolitis: review of the literature and state of the art

Necrotizing enterocolitis (NEC) remains the leading cause of gastrointestinal surgical emergency in preterm neonates. Over the last five decades, a variety of experimental models have been developed to study the pathophysiology of this disease and to test the effectiveness of novel therapeutic strategies. Experimental NEC is mainly modeled in neonatal rats, mice and piglets. In this review, we focus on these experimental models and discuss the major advantages and disadvantages of each. We also briefly discuss other models that are not as widely used but have contributed to our current knowledge of NEC.

The β-glucosidase assay: a new diagnostic tool for necrotizing enterocolitis. Sensitivity, specificity, and predictive values

We aimed to establish the utility of serum cytosolic β-glycosidase (CBG) assay as a NEC diagnosis tool. CBG activity has been compared in 192 NEC-free (NEC(-)) and 13 NEC-affected (NEC(+)) neonates, with modified Bell's stages II/III, born at Reina Sofia University Hospital; additional blood hematology, microbiology, and biochemical parameters have been assayed. NEC(+) neonates have higher serum CBG activity, 26.4 ± 12.4 mU/mg; 95 % CI (18.8-33.9), than NEC(-) infants, 11.0 ± 6.6 mU/mg; 95 % CI (10.1-11.9) (p < 0.0001). The CBG cutoff value in the ROC curve, 15.6 mU/mg, discriminates NEC(+)/NEC(-) infants with 84.6 % sensitivity, 85.9 % specificity, 37.9 positive predictive value and 98.2 negative predictive value, 6.11 positive likelihood ratio and 0.18 negative likelihood ratio, 33.61 DOR, and 0.89 AUC. A combined panel [CBG + aspartate aminotransferase + C-reactive protein] shows a 0.90 AUC value in multiple linear regressions.

CONCLUSIONS

The serum CBG level is a good NEC diagnosis test and a novel NEC biomarker which may become a screening tool.

WHAT IS KNOWN

•NEC affects ∼2.5 % of infants at NICU, ∼90 % of them weighing <1500 g. •NEC requires a careful differential diagnosis, being lethal if not diagnosed and treated. What is new: •CBG assay will be useful to determine infants without NEC and preventing unnecessary treatment. •CBG assay could discriminate NEC better than other gut-specific sera protein biomarkers.

Current status on plasma biomarkers for acute mesenteric ischemia

Clinical diagnosis of acute mesenteric ischemia is difficult. The aim of this review is to provide current status on the search for an accurate plasma biomarker for acute mesenteric ischemia. A search using the medical subject heading terms marker and mesenteric ischemia or intestinal ischemia or superior mesenteric artery occlusion or mesenteric venous thrombosis in the Medline and Embase databases from 1980 to 2011. Studies without a control group or a control group consisted of healthy individuals (human studies), or studies on intestinal reperfusion were excluded. Twenty animal and twelve human studies were identified. In human studies, the studied series of patients had a control group that had a need of laparotomy (n = 2), suspected acute mesenteric ischemia (n = 7), acute abdomen (n = 2) or systemic inflammatory response syndrome (n = 1). D: -dimer has been found to be the most consistent highly sensitive early marker, but specificity was low. The follow-up study on α-glutathione S-transferase yielded inferior sensitivity and accuracy than the preliminary study, clearly questioning the value of this marker. Intestinal fatty acid binding globulin (I-FABP) and D: -lactate are both interesting markers, but the results were conflicting. Different cut-off levels have been used in the studies on I-FABP. The encouraging preliminary result of cobalt-albumin and urinary FABP as an accurate marker needs to be addressed in other study populations. The early clinical and laboratory diagnosis of intestinal ischemia remains a challenge. None of the proposed plasma-derived tests for acute mesenteric ischemia has as yet entered routine clinical practice. The proposed biomarkers need to be evaluated in a prospective clinical research project in patients with acute abdomen.

Toll-like receptor 4 is protective against neonatal murine ischemia-reperfusion intestinal injury

PURPOSE

Premature infants receiving probiotics have a decreased incidence of necrotizing enterocolitis. This may be mediated by intestinal bacterial signaling via toll-like receptors (TLRs) 2 and 4 maintaining intestinal homeostasis. We hypothesized that TLRs 2 and 4 are protective against ischemia-reperfusion (I/R) intestinal injury.

METHODS

Two-week-old C57BL/6 wild-type (WT), B6.TLR2(-/-), B6.TLR4(-/-), B6.TLR2(-/-)4(-/-), and microbially reduced (antibiotic-treated) mice (MR) underwent 60 minutes of superior mesenteric artery occlusion (I) followed by 90 minutes of reperfusion (R). Small intestine was harvested for analysis of microscopic injury, apoptosis, and inflammatory gene expression using quantitative polymerase chain reaction.

RESULTS

After I/R, the median histologic injury scores of the B6.TLR4(-/-), B6.TLR2(-/-)4(-/-), and MR pups were higher than the WT or B6.TLR2(-/-) pups that corresponded with greater apoptosis based on terminal deoxynucleotidyl transferase-mediated dUTP-FITC nick-end labeling and activated caspase-3 immunostaining. B6.TLR4(-/-), B6.TLR2(-/-)4(-/-), and MR also had elevated tissue innate immunity-associated chemokine and cytokine expression.

CONCLUSIONS

Neonatal mice deficient in TLR4, either alone or also deficient in TLR2, as well as those lacking a normal commensal intestinal microbiome are more susceptible to an I/R model of intestinal injury. These results may provide a mechanism for commensal bacterial-mediated protection, which may help to direct further studies to elucidate the mechanism of probiotic protection.

Timing of surgical intervention in necrotizing enterocolitis can be determined by trajectory of metabolic derangement

PURPOSE

Seven metrics of metabolic derangement were evaluated as contributors to clinical decision support for operative intervention in infants with suspected necrotizing enterocolitis (NEC).

METHODS

Records of infants with suspected NEC without radiologic evidence of free air were queried for presence of 7 components of metabolic derangement (CMD), consisting of positive blood culture, acidosis, bandemia, thrombocytopenia, hyponatremia, hypotension, or neutropenia. Cases were stratified by clinical decision after each surgical evaluation as observation (OBS) or intervention (INT). Good outcome was defined as full enteric feeding by discharge and bad outcome as death or ongoing parenteral alimentation. Eleven infants undergoing operative intervention after an initial decision to observe were evaluated as matched pairs. Components of metabolic derangement/case and frequency of each CMD were determined for OBS and INT. Mann-Whitney U test was used to compare proportions of CMD in each group. Outcome was compared using chi(2). Observation was then stratified by outcome to determine whether 3 or more metabolic derangements warranting operative intervention would have changed initial clinical decision. The 11 matched cases were similarly analyzed using Wilcoxon-matched pairs.

RESULTS

Between March 2005 and July 2008, 35 infants with NEC received 53 surgical evaluations. A median of 1 CMD/case was defined in 32 instances of OBS. Surgical intervention was carried out in 19 infants with a median of 3 CMD/case. Mann-Whitney U test indicated significant difference in the frequencies of each CMD component in OBS vs INT (P = .04). Good outcome was achieved in 75% of OBS and 63% of INT (non-significant, NS). Analysis of OBS by outcome demonstrated a median 1 CMD/case of 25 with good outcome and 3 CMD/case in infants with bad outcome. Frequency of CMD was significantly higher in infants with bad outcome (P = .02). Wilcoxon-matched pair analysis of the 11 infants with paired evaluations demonstrated a similar distribution and frequency of CMD.

CONCLUSION

Progressive metabolic derangement of infants with NEC can be clinically tracked. The appearance of any 3 of these 7 metrics indicates timely operative intervention. Application of CMD trajectory to timing of surgical intervention may improve outcome and define the relationship between specific CMD and operative risk.

Prevention of necrotising enterocolitis: Year 2004 and beyond

The incidence of necrotising enterocolitis (NEC) has not changed significantly despite the dramatic advances in perinatal-neonatal care. The absolute number of survivors of NEC is expected to rise, as prevention of prematurity, the single most important risk factor for the illness, continues to be difficult. Prevention of NEC has thus become an area of research priority. Given the role of inflammatory mediators in its pathogenesis newer immune modulators are being studied as potential agents for prevention/treatment of NEC. Caution, however, is warranted because the failure of sepsis trials in adults has clearly indicated that the concept of down-regulating the inflammatory response is deceptively simple. Clinical trials of any such promising preventative agent(s) need to be designed carefully and must include long-term neurodevelopmental outcomes as almost an entire population of high-risk preterm neonates will be exposed to their adverse effects. As new frontiers continue to be explored, the proven benefits of simple and safe interventions like antenatal glucocorticoid therapy and the preferential use of breast milk for feeding high-risk neonates must not be forgotten. Given that a single effective agent is unlikely in the near future, utilizing a package of "potentially better practices" seems to be the most appropriate strategy to prevent and minimize NEC.

The development of animal models for the study of necrotizing enterocolitis

Necrotizing enterocolitis (NEC) is the leading cause of death and long-term disability from gastrointestinal disease in preterm infants, and is characterized by acute and chronic intestinal inflammation that may lead to systemic sepsis and multi-system organ failure. NEC typically develops in the preterm infant after the administration of tube feeds, although it may occasionally be seen in full-term babies. Despite extensive clinical experience in the management of patients with NEC, the underlying cellular and molecular mechanisms leading to its development remain incompletely understood. Several animal models have therefore been developed in a variety of species in order to study the pathogenesis of NEC and to develop more effective treatment strategies. This review seeks to examine the pros and cons of animal models that have been developed in the study of NEC over the past 30 years. It will highlight the various strengths and weaknesses of experimental approaches that have been used, and discuss potential directions for the development of such models for the future.

Enteral feeding reduces endothelial nitric oxide synthase in the caudal intestinal microvasculature of preterm piglets

The initiation of enteral feeding represents a challenge to the neonatal intestinal microcirculation, especially in preterms where it predisposes to necrotizing enterocolitis (NEC). We hypothesized that a structural microvascular deficiency may occur when enteral feeding is initiated in preterm piglets susceptible to NEC. Stereologic volume densities of a pan-endothelial marker (vWF), and the main vasodilator endothelial nitric oxide synthase (eNOS), were determined along the small intestine of 1) unfed preterm piglets, 2) piglets receiving total parenteral nutrition (TPN) for 2-3 d, and 3) piglets fed 2 d sow's colostrum (TPN+SOW) or milk formula (TPN+FOR) following TPN. In the mucosa, vWF-density decreased in a cranio-caudal direction. A corresponding mucosal eNOS gradient appeared only after initiating enteral feeding. In TPN+SOW, eNOS induction may lag behind the mucosal growth of the caudal region. In TPN+FOR, formula-related factors (i.e. bacteria, cytokines) may suppress mucosal eNOS, indicated by increased stress-sensitive nuclear HIF1alpha staining. The low mucosal endothelial eNOS density was related to the presence of NEC lesions, maybe via increased hypoxia-sensitivity, especially in the caudal region as indicated by nuclear HIF1alpha-staining. Our results suggest an insufficient structural adaptation of the microvasculature to enteral feeding, especially of mucosal eNOS, which may lead to NEC.

Roles of cyclooxygenase-2 and prostacyclin/IP receptors in mucosal defense against ischemia/reperfusion injury in mouse stomach

We examined the roles of cyclooxygenase (COX) isozymes, prostaglandins (PGs), and their receptors in the mucosal defense against ischemia/reperfusion (I/R)-induced gastric lesions in mice. Male C57BL/6 mice, including wild-type animals and those lacking prostaglandin E(2) (EP)1, EP3, or prostaglandin I(2) (IP) receptors, were used after 18 h of fasting. Under urethane anesthesia, the celiac artery was clamped (ischemia) for 30 min, and then reperfusion was achieved for 60 min through the removal of the clamp, and the stomach was examined for lesions. I/R produced hemorrhagic gastric lesions in wild-type mice. The severity of lesions was significantly increased by pretreatment with indomethacin (a nonselective COX inhibitor) and rofecoxib (a selective COX-2 inhibitor) but not 5-(4-chlorophenyl)-1-(4-methoxyphenyl)-3-(trifluoromethyl)-1H-pyrazole (SC-560; a selective COX-1 inhibitor). The expression of COX-2 mRNA was up-regulated in the stomach following I/R but not by sham operation or ischemia alone. The ulcerogenic response was markedly aggravated in IP receptor knockout mice but not those lacking EP1 or EP3 receptors. I/R increased the levels of 6-keto-PGF(1alpha) and PGE(2) in the stomach of wild-type mice, and this response was attenuated by indomethacin and rofecoxib but not SC-560. Pretreatment of wild-type mice with iloprost, a prostacyclin (PGI(2)) analog, significantly prevented the I/R-induced gastric lesions in the absence and presence of indomethacin or rofecoxib. PGE(2) also reduced the severity of I/R-induced gastric lesions, yet the effect was much less pronounced than that of iloprost. These results suggest that endogenous PGs derived from COX-2 play a crucial role in gastric mucosal defense during I/R, and this action is mainly mediated by PGI(2) through the activation of IP receptors.

Alcohol dehydrogenase: A potential new marker for diagnosis of intestinal ischemia using rat as a model

AIM: Intestinal ischemia (Ii) is an abdominal emergency due to blockade of the superior mesenteric artery resulting in 60-100% mortality if diagnosed late. Changes in several biochemical parameters such as D (-)-lactate, Creatinine kinase isoenzymes and lactate dehydrogenase suggested for early diagnosis, lack specificity and sensitivity. Therefore a biochemical parameter with greater sensitivity needs to be identified.

METHODS: Wistar male rats were randomly assigned into two groups; control sham operated (n = 24) and ischemic test (n = 24) group. Superior mesenteric arterial occlusion was performed in the ischemic test group for 1 h. Alcohol dehydrogenase (ADH) was estimated in blood from portal vein, right ventricle of heart, dorsal aorta (DA) and inferior vena cava (IVC). The Serum glutamic acid pyruvate transaminase (SGPT) was also estimated in blood from portal vein and right ventricle of heart.

RESULTS: A significant increase (P<0.001) in the levels of ADH in both portal blood as well as heart blood of the test group (232.72±99.45 EU and 250.85±95.14 EU, respectively) as compared to the control group (46.39±21.69 EU and 65.38±30.55 EU, respectively) were observed. Similarly, increased levels of ADH were observed in blood samples withdrawn from DA and IVC in test animals (319.52±80.14 EU and 363.90±120.68 EU, respectively) as compared to the control group (67.68±63.22 EU and 72.50±58.45 EU, respectively). However, in test animals there was significant increase in SGPT in portal blood (P = 0.054) without much increase in heart blood.

CONCLUSION: Significant increase in the levels of ADH in portal and heart blood within 1 h of SMA occlusion without increase in SGPT in heart blood, suggests that the origin of ADH is from ischemic intestine and not from liver. Similarly, raised ADH levels were found in DA and IVC as well. IVC blood does represent peripheral blood sample. A raised level of ADH in test animals confirms it to be a potential marker in the early diagnosis of Ii.

Current issues in the management of necrotizing enterocolitis

Necrotizing enterocolitis (NEC) is the most common surgical emergency in the neonatal intensive care unit and remains a major cause of death in neonates. Although the pathophysiology of NEC has not been completely elucidated, progress has been made in the characterization of the molecular events which may take place during an episode of ischemia. This possible initiating event is followed by a complex cascade of inflammatory mediators active in NEC: epidermal growth factor, platelet-activating factor, and, nitric oxide. Additionally, unique characteristics of the premature gut are thought to be crucial to the development of NEC. The diagnosis of NEC continues to be based on clinical and radiographic features. Several new laboratory tests are under investigation for the purposes of earlier diagnosis, but none have prevailed at this time. Both exploratory laparotomy, with intestinal resection and peritoneal drainage are widely practiced. Mortality rates remain high and have improved little over the last couple of decades. Therefore, prevention remains crucial in order to decrease the incidence of NEC. Cautious feeding regimens, the use of maternal breast milk, passive immunization, and the use of probiotics have all been suggested but not proven as possible preventive methods. Although many advances have been made, significant opportunity remains to improve our understanding of the disease process and to develop better strategies for prevention and treatment.

Circulating CXC-chemokine concentrations in a murine intestinal ischemia-reperfusion model

BACKGROUND

CXC-chemokines bearing the glutamic acid-leucine-arginine (ELR) motif (ELR+ CXC chemokines) are potent neutrophil chemoattractants and hence may play a role in mucosal injury seen with intestinal ischemia-reperfusion (I/R).

METHODS

Serum concentrations of ELR+ CXC chemokines (keratinocyte-derived chemokine(KC) / CXC ligand (CXCL) 1, macrophage inflammatory protein (MIP)-2/CXCL 2/3, lipopolysaccharide-induced CXC chemokine (LIX) / CXCL5, and lungkine/CXCL15) were measured in a murine intestinal I/R model. Fifteen 4-week-old wild-type mice were studied in three subgroups: sham, ischemia (superior mesenteric artery [SMA] clamping for 60 min) and ischemia-reperfusion (SMA clamping for 60 min followed by reperfusion for 90 min).

RESULTS

Concentrations of KC/CXCL1 and MIP-2/CXCL2/3 in sham-treated animals (145 +/- 123 and 107 +/- 55 pg/mL, respectively) and the ischemia subgroup (646 +/- 413 and 226 +/- 129 pg/mL) were similar, but concentrations were signifcantly higher with reperfusion (6398 +/- 2297, p < .001 and 874 +/- 790 pg/mL, p = .04). LIX/CXCL5 and lungkine/CXCL15 concentrations did not change significantly with ischemia or following I/R. KC/CXCL1 and MIP-2/CXCL2/3 concentrations correlated positively with the severity of mucosal injury and with each other, whereas a negative relationship was observed between LIX/CXCL5 concentrations and microscopic injury scores.

CONCLUSIONS

Development of mucosal injury in intestinal I/R is associated with increased serum concentrations of KC/CXCL1 and MIP-2/CXCL2/3, but not with those of LIX/CXCL5 and lungkine/CXCL15.