Animal Model Of Necrotizing Enterocolitis Research Articles

Models of necrotizing enterocolitis

Necrotizing enterocolitis (NEC) is the leading cause of death and disability from gastrointestinal disease in premature infants. The mortality of patients with NEC is approximately 30%, a figure that has not changed in many decades, reflecting the need for a greater understanding of its pathogenesis. Progress towards understanding the cellular and molecular mechanisms underlying NEC requires the study of highly translational animal models. Such animal models must mimic the biology and physiology of premature infants, while still allowing for safe experimental manipulation of environmental and microbial factors thought to be associated with the risk and severity of NEC. Findings from animal models have yielded insights into the interactions between the host, the colonizing microbes, and the innate immune receptor Toll-like Receptor 4 (TLR4) in driving disease development. This review discusses the relative strengths and weaknesses of available in vivo, in vitro, and NEC-in-a-dish models of this disease. We also highlight the unique contributions that each model has made to our understanding of the complex interactions between enterocytes, microbiota, and immune cells in the pathogenesis of NEC. The overall purpose of this review is to provide a menu of options regarding currently available animal models of NEC, while in parallel hopefully reducing the potential uncertainty and confusion regarding NEC models to assist those who wish to enter this field from other disciplines.

Prenatal Heparin-Binding Epidermal Growth Factor–Like Growth Factor Administration Decreases Lung Inflammation in the Experimental Model of Necrotizing Enterocolitis

INTRODUCTION: Necrotizing enterocolitis (NEC) is the leading gastrointestinal cause of death in premature infants. Postnatal enteral and prenatal intraperitoneal Heparin-Binding EGF-like Growth Factor (HB-EGF) administration has decreased the incidence and severity of intestinal injury in a neonatal rat model of NEC. The aim was to determine the effect of prenatally administered HB-EGF on lung injury in neonatal rats exposed to the experimental model of NEC. METHODS: Pregnant rats and pups were separated into 3 groups: control (natural birth, no NEC protocol, no HB-EGF), NEC (cesarean section, NEC protocol), and HB-EGF (prenatal HB-EGF administration, cesarean section, NEC protocol). Pregnant rats were given HB-EGF (800 μg/kg/dose) via intraperitoneal injection 2 hours before timed cesarean section. After delivery, the premature rat pups were exposed to the NEC model (hypercaloric feds, hypothermia, and hypoxia). Pups were sacrificed upon clinical signs of NEC; the intestines and lungs were hematoxylin and eosin stained for grading. RESULTS: The median alveolar wall thicknesses were significantly different between control (71,646 μm2) vs NEC (75,398 μm2; p < 0.0001) and HB-EGF (71,646 μm2) vs NEC (p < 0.0001); however, the control and HB-EGF groups were similar (p = 0.307; Fig. 1A). The median alveolar areas were significantly different between control (85.23 μm2) vs NEC (66.40 μm2; p < 0.0001) and HB-EGF (64.14 μm2) vs NEC (p < 0.0001); however, again, the control and HB-EGF were similar (p = 0.215; Fig. 1B).CONCLUSION: Our results support the prenatal HB-EGF role in preventing lung injury by means of preserving alveolar wall thickness and alveolar surface area in this animal model of NEC; therefore, maternal administration of HB-EGF before delivery in prematurity could protect lungs from NEC-related injury.

A Mouse Model of Necrotizing Enterocolitis.

Necrotizing enterocolitis (NEC) is an acute inflammatory disease that unforeseeably develops in very low birth weight premature infants. NEC is characterized by impairment of the intestinal barrier resulting in intestinal necrosis and multisystem organ failure. Animal models of NEC have contributed significantly to a better understanding of the underlying molecular mechanisms of the disease and facilitated the exploration of potential new therapeutic strategies. Here, we provide a detailed protocol that recapitulates some of the main histological and transcriptional features of human NEC in newborn mice.

An enhanced Lactobacillus reuteri biofilm formulation that increases protection against experimental necrotizing enterocolitis.

One significant drawback of current probiotic therapy for the prevention of necrotizing enterocolitis (NEC) is the need for at least daily administration because of poor probiotic persistence after enteral administration, increasing the risk of the probiotic bacteria causing bacteremia or sepsis if the intestines are already compromised. We previously showed that the effectiveness of Lactobacillus reuteri ( Lr) in preventing NEC is enhanced when Lr is grown as a biofilm on the surface of dextranomer microspheres (DM). Here we sought to test the efficacy of Lr administration by manipulating the Lr biofilm state with the addition of biofilm-promoting substances (sucrose and maltose) to DM or by mutating the Lr gtfW gene (encoding an enzyme central to biofilm production). Using an animal model of NEC, we determined that Lr adhered to sucrose- or maltose-loaded DM significantly reduced histologic injury, improved host survival, decreased intestinal permeability, reduced intestinal inflammation, and altered the gut microbiome compared with Lr adhered to unloaded DM. These effects were abolished when DM or GtfW were absent from the Lr inoculum. This demonstrates that a single dose of Lr in its biofilm state decreases NEC incidence. Importantly, preloading DM with sucrose or maltose further enhances Lr protection against NEC in a GtfW-dependent fashion, demonstrating the tunability of the approach and the potential to use other cargos to enhance future probiotic formulations. NEW & NOTEWORTHY Previous clinical trials of probiotics to prevent necrotizing enterocolitis have had variable results. In these studies, probiotics were delivered in their planktonic, free-living form. We have developed a novel probiotic delivery system in which Lactobacillus reuteri (Lr) is delivered in its biofilm state. In a model of experimental necrotizing enterocolitis, this formulation significantly reduces intestinal inflammation and permeability, improves survival, and preserves the natural gut microflora compared with the administration of Lr in its free-living form.

Dual purpose use of preterm piglets as a model of pediatric GI disease

Necrotizing enterocolitis (NEC) is the most common gastrointestinal complication in human neonates, yet the pathogenesis of this disease remains poorly understood. A fundamental approach to understanding the etiology and underlying biology of NEC is the use of in vivo experimental animal models, primarly neonatal rodents and pigs. The rodent models using rats and mice have provided a much of the experimental evidence showing the protective influence of breast milk and the role of specific molecular mechanisms involved in the premature innate immune and intestinal injury response. A key advantage of mice is the abilty to test how genetic disruption of specific genes alters the NEC phenotype. More recently, pigs have emerged as an animal model of NEC and used to establish the role of bacterial colonization, prematurity, parenteral nutrition and antibiotic therapy. This review will outline some of the advantages and disadvantages of both rodent and pig models and highlight the lessons learned about NEC pathobiology from these different experimental models.

Paneth cells and necrotizing enterocolitis

Necrotizing enterocolitis (NEC) is a common and devastating disease of premature infants. Immaturity of the innate immune system of the gut is central to the pathogenesis of NEC. Recent studies suggest a key role for Paneth cells in this disease. Addressing basic questions on the development and function of immature Paneth cells may shed light on the puzzling pathophysiology of NEC. Current animal models of NEC are limited in their capacity to answer these questions.

Intestinal epithelial apoptosis initiates gross bowel necrosis in an experimental rat model of neonatal necrotizing enterocolitis.

The histopathology of necrotizing enterocolitis (NEC) is characterized by destruction of the mucosal layer in initial stages and by transmural necrosis of the intestinal wall in advanced stages of the disease. To test the hypothesis that enhanced epithelial apoptosis is an initial event underlying the gross histologic changes, we analyzed epithelial apoptosis and tissue morphology in an animal model of NEC and evaluated the effect of caspase inhibition on the incidence of experimental NEC in this model. Apoptosis was analyzed with terminal deoxynucleotidyltransferase-mediated dUTP-FITC nick end labeling (TUNEL) staining in intestinal sections and by measuring caspase 3 activity from intestinal lysates of neonatal rats subjected to formula feeding and cold/asphyxia stress (FFCAS) and from mother-fed (MF) controls. Morphologic evaluation was based on hematoxylin and eosin staining of intestinal sections. FFCAS resulted in histologic changes consistent with NEC, which were absent from MF animals. FFCAS was also associated with a significantly increased rate of nuclear DNA fragmentation in the small intestinal epithelium compared with MF. Elevated tissue caspase 3 activity confirmed the presence of apoptosis in samples with increased DNA fragmentation. Analysis of the coincidence of morphologic damage and apoptosis in corresponding tissue sections indicated that apoptosis precedes gross morphologic changes in this model. Furthermore, supplementation of formula with 8 boc-aspartyl(OMe)-fluoromethylketone, a pan-caspase inhibitor, significantly reduced the incidences of apoptosis and experimental NEC. These findings indicate that in neonatal rats FFCAS induces epithelial apoptosis that serves as an underlying cause for subsequent gross tissue necrosis.

Platelet-activating factor, tumor necrosis factor, hypoxia and necrotizing enterocolitis.

The pathogenesis of necrotizing enterocolitis (NEC) is poorly understood. We have established several animal models of NEC by using a combination of various stimuli and stress, including endotoxin, PAF, TNF, and hypoxia. We discuss the mechanism of their actions and the possible roles of these factors in the pathogenesis of human NEC.