L’épithélium intestinal est une monocouche de cellules qui tapisse la lumière intestinale, constitué d’un compartiment différencié, les villosités dans l’intestin grêle et les plateaux épithéliaux dans le colon, et d’un compartiment prolifératif, les cryptes de Lieberkühn. Ce tissue se renouvelle de façon rapide et continue tout au long de la vie de l’individu, grâce à la présence de cellules souches adultes dans le fond des cryptes. Ces cellules s’autorenouvellent et donnent naissance à des progéniteurs prolifératifs (capables d’engendrer les différents cytotypes épithéliaux) qui se différencient tout en migrant vers le compartiment différencié. Mon travail de these a porté sur l’étude d’une marqueur putatif de ces cellules souches épithéliales intestinales: Musashi1 (Msi1).Dans ce contexte, mon premier axe d’étude s’est focalisé sur l’isolement et la caractérisation des cellules souches épithéliales intestinales chez la souris. Pour cela, nous avons généré des souris transgéniques exprimant la protéine fluorescente GFP sous le contrôle du promoteur de Msi1. Les cellules souches intestinales de ces souris coexpriment donc Msi1 et la GFP. Ce modèle a été validé et nous à permis de isoler les cellules GFP/Msi1 positives dans l’intestin. A l'aide de différentes approches cellulaires et moléculaires, nous avons confirmé leur nature de cellules souches et nous avons apporté des nouvelles données sur la composition de la zone proliférative de l’épithélium intestinal murin.Le second axe de mes travaux de thèse a porté sur l’étude de la fonction de Msi1 dans l'homéostasie de l’épithélium intestinal chez la souris, par son sur-expression tous au long de l’épithélium. Nous avons montré que la sur-expression de cette protéine, qui est un régulateur des voies Wnt et Notch, perturbe l’architecture intestinale, a propriétés pro-prolifératives et un potentiel tumorigènique. / The intestinal epithelium is a monolayer of cells surrounding the intestinal lumen. It consists of a differentiated compartment, the villi in the small intestine and a flat surface in the colon, and a proliferative compartment, the crypts of Lieberkühn. This tissue self-renews rapidly and continuously throughout life, due to the presence of adult stem cells in the bottom of the crypts. These cells are capable of self-renewing and give rise to proliferating progenitors (capable of generating all the different epithelial cytotypes) that differentiate and migrate toward the differentiated compartment. My thesis focused on the study of the intestinal epithelial stem cells marker Musashi1 (Msi1).In this context, the first part of my thesis work focused on the isolation and characterization of the intestinal epithelial stem cells that express Msi1 in the mouse. For this, we generated transgenic mice expressing the fluorescent protein GFP under the control of the promoter of Msi1. The intestinal stem cells of these mice co-express Msi1 and GFP. This model has been validated and allowed us to isolate GFP+/Msi-expressing cells in the intestine. By using different cellular and molecular approches, we confirmed their nature of stem cells and provided new data on the composition of the proliferative zone in the murine intestinal epithelium.The second part of my thesis has focused on the study of the function of Msi1 in the intestinal epithelium homeostasis in the mouse, by its over- and ectopic expression all along the epithelium. We have shown that the over-expression of this protein, which is a regulator of the Wnt and Notch pathways, perturbs the intestinal architecture, has pro-proliferative properties and tumorigenic potential.

L'épithélium intestinal adulte des mammifères est un tissu hautement organisé entièrement renouvelé tous les 5 à 7 jours, grâce à la présence de cellules souches intestinales (CSI). Localisées à la base des cryptes, les CSI sont capables de s'auto-renouveler et de générer l'ensemble des types cellulaires de ce tissu. Afin de préserver l'équilibre entre leur auto-renouvellement et leur différenciation, véritable garant de l'homéostasie de l'épithélium intestinal, les CSI résident dans un microenvironnement finement régulé, « la niche », leur procurant l'ensemble des signaux nécessaires à leurs fonctions. La Nétrine-1, molécule sécrétée et apparentée à la famille des Laminines, est exprimée dans l'environnement des cryptes intestinales, mais également au cours du développement intestinal. Initialement découverte pour son rôle dans le guidage axonal, cette protéine est à ce jour considérée comme une molécule pléïotropique impliquée dans divers processus physiologiques tels que la morphogénèse, la migration, l'adhésion cellulaire, la prolifération mais également pathologiques comme la tumorigénèse. Considérant ces observations nous nous sommes donc intéressés au rôle potentiel de la Nétrine-1 dans la régulation du compartiment souche intestinal adulte, ainsi que lors de l'ontogénèse intestinale. Dans une première partie, nous montrons qu'ex vivo la Nétrine-1 promeut la croissance des entéroïdes et régule l'expression génique de certains marqueurs spécifiques des CSI. Dans une seconde partie, nous montrons, grâce à la génération et caractérisation de nouveaux modèles murins, que la Nétrine-1 est impliquée dans le développement de l'épithélium intestinal grêle et que sa délétion conduit à un retard d'émergence des villi / The adult intestinal epithelium is a highly organized tissue, which is completely self-renewed every 5 to 7 days, due to a pool of multipotent intestinal stem cells (ISC). Located at the base of intestinal crypts, ISC have the ability to self- renew and to give rise to all epithelial intestinal cell types. To preserve the balance between their self-renewal and their differentiation, and therefore to maintain the epithelial tissue homeostasis, ISC reside in a tightly regulated microenvironment - called “niche”- that provides them all factors required for their functions. Netrin-1, a laminin-related secreted protein, is expressed in the microenvironment of the crypt, and is also expressed during intestinal development. Initially described as an axonal guidance cue, Netrin-1 is now considered as a pleiotropic molecule involved in many different processes such as morphogenesis, cell migration, cell adhesion, proliferation and also tumorigenesis. Based on these observations, we hypothesized that Netrin-1 could play a role in the maintenance of the adult intestinal stem cell compartment, and also in the intestinal ontogenesis. In a first part, we showed that Netrin-1 promotes the growth of enteroids ex vivo while regulating gene expression of specific intestinal stem cell markers. In the second part, we demonstrated, by using two novel genetically engineered mouse models, that Netrin-1 is involved in the embryonic development of the intestinal epithelium and that its deletion leads to a delay in villi emergence

O diabetes mellitus tipo 2 (DM2) é uma doença de prevalência crescente na população mundial, sendo associado ao aumento de diversas comorbidades. A relação entre o trato digestivo e o DM2 tem sido fortalecida a partir dos resultados das diferentes cirurgias metabólicas frente à remissão do distúrbio endócrino. Alterações morfológicas hipertróficas no epitélio intestinal são percebidas nos estágios iniciais da doença e parece ter papel primordial na instalação da hiperglicemia crônica. O gene p53 participa ativamente dos processos de regulação do crescimento epitelial intestinal e pode sofrer alteração de sua expressão em estados diabéticos. Objetiva-se avaliar os resultados clínicos e laboratoriais de pacientes DM2 e com índice de Massa Corpórea (IMC) >25 e <35 Kg/m2 submetidos a cirurgia metabólica denominada adaptação digestiva com duodenal switch parcial (DSP) e avaliar o comportamento da expressão do gene p53 na mucosa intestinal no período pré e pós-operatório. Nove pacientes DM2, com IMC<35Kg/m2 foram operados pela técnica DSP. Biópsias de duodeno e íleo foram colhidas no estado diabético (pré e transoperatório respectivamente) e, 3 meses após a cirurgia, através de endoscopia digestiva alta. Foram comparados os dados de evolução antropométrica (IMC) e laboratorial no período pré e pós-operatório. Através do método enzyme-linked immunosorbent assay (ELISA) foram determinados os níveis dos entero-hormônios glucagon-like peptide-1 (GLP-1) e glucose-dependent insulinotropic peptide (GIP), no pré e pós-operatório, em jejum e pós-prandial nos períodos 30',60',90' e 120'. A expressão do gene p53, foi avaliada por real time polymerase chain reaction (qrt-PCR) e western blot, nos dois diferentes momentos. As variáveis: glicemia de jejum e pós-prandial (2 horas), trigliceridemia de jejum, hemoglobina glicada (HbAc1) e peptídeo C foram analisadas. As médias dos parâmetros laboratoriais foram comparadas pela análise multivariada ANOVA e após teste-Tukey. A média de expressão relativa do gene p53 foi comparada nos dois períodos pelo teste t-student. Os resultados evidenciaram que entre maio e dezembro de 2010, nove pacientes (4 homens, 5 mulheres) DM2 e com IMC entre 26 e 34Kg/m2 foram submetidos a DSP. A média de IMC do grupo operado foi de 31,3. Houve queda do IMC média de 23% após um ano. Houve queda significativa (p<0,05) nos níveis de triglicerídeos, glicemia de jejum e pós-prandial (2 horas), HbA1c assim como aumento do peptídeo-C (p<0,05), quando comparados os períodos pré e pós-operatório. Os níveis séricos de GLP-1 foram significativamente maiores no pós-operatório (p<0,05), tanto em jejum como pós-prandial sendo que houve diminuição dos níveis de GIP, contudo sem significância estatística. O gene p53 sofreu aumento significativo de sua expressão relativa (qrt-PCR)(p<0,05) no período pós-operatório na mucosa duodenal e uma tendência de aumento no íleo, contudo sem significância estatística. A análise da expressão ao nível proteico foi bem sucedida somente no íleo, também mostrando tendência de aumento. Concluí-se que a DSP foi capaz de controlar satisfatoriamente o DM2 em pacientes com IMC<35 Kg/m2. Houve aumento da secreção de GLP-1 e tendência de diminuição do GIP. Houve aumento da expressão do p53 na mucosa intestinal, no período pós-operatório, após o controle do diabetes, quando comparada ao período pré-operatório. / Diabetes mellitus type 2 (DM2) is a worldwide increasing prevalence disease, being related to a variety of comorbidities. The relationship between the digestive tract and DM2 has been strengthened by the results of different metabolic surgery procedures on resolution of the endocrine disorder, before weigh loss achievement. Hypertrophic morphological changes in the intestinal epithelium are observed in the early stages of disease development and seems to have a pivotal role in the establishment of chronic hyperglicemia. The p53 gene directly participates on regulation of growth processes of the intestinal epithelium, and its expression has been shown to be altered in diabetic states.The objectives were to evaluate clinical and laboratory results in DM2 patients, presenting Body Mass Index(BMI)>25 and <35Kg/m2, undergoing a metabolic surgery procedure called digestive adaptation with partial duodenal switch(DSP). To assess p53 gene expression behavior in intestinal mucosa, on pre and postoperative period. Nine patients presenting DM2 and BMI below 35Kg/m2 underwent DSP.Biopsies of the duodenum and intermediate portion of the ileum were undertaken in diabetic state (pre and transoperative respectively) and 3 months after surgery by upper gastrointestinal endoscopy. The evolution of anthropometric (BMI) and laboratory parameters were acessed on postoperative period. Serum levels of enterohormones glucagon-like peptide-1(GLP-1) and glucose-dependent insulinotropic peptide (GIP) were determined by the method enzyme-linked immunosorbent assay (ELISA), pre and postoperatively, on fasting and postprandial state (30',60'90 and 120') after ingestion of a standart meal.The p53 gene expression was evaluated by real time polymerase chain reaction (qrt-PCR) and western blot, on two different periods. The variables: fasting and postprandial (2 hours) glicemia, fasting triglycerides (TG), glycosylated hemoglobin (HbA1c) and C-peptide were undertaken. The mean levels of laboratorial parameters were compared by mulivariate analyses (ANOVA) and Tukey test. The mean expression of the p53 gene was compared in two different periods by T test. Between may and December 2010, four men and 5 women were operated on. The mean BMI was 31,1. There was a decrease in BMI of 23% after one year of surgery. There was a significant decrease (p<0,05) on fasting TG and HbA1c levels as well as glucose levels on fasting and postprandial state (2 hours) when compared pre and postoperatively. There was an increase (p<0,05) in C-peptide levels after surgery. Serum levels of GLP-1 were significantly higher postorperatively (p<0,05), on both fasting and postprandial condition, and there was a decrease,not significant, on GIP levels. The p53 relative gene expression showed a significant increase (p<0,05) in the postoperative period in duodenal mucosa (transcriptional state) and showed an increasing trend in the ileum, but not statistically significant. Only ileum portion results were succesfully acessed by western blot analisys, showing an increasing trend as well. The DSP procedure was succesfully capable to control type 2 diabetes in patients presenting BMI<35 Kg/m2. There was a significant enhancement of GLP-1 secretion and a decreasing trend for GIP on postoperative period. There was increased expression of mucosal p53 in the postoperative period after the control of DM2, when compared to diabetic pre-operative state.

Orientador: Maria Aparecida Marchesan Rodrigues / Resumo: Introdução: A Displasia Neuronal Intestinal, tipo B (DNI-B) é uma doença neuromuscular gastrointestinal caracterizada por alterações complexas do sistema nervoso entérico. Seu diagnóstico depende da análise histopatológica de biópsias do reto, com mudanças dos critérios diagnósticos ao longo dos anos, o que dificulta a prática diagnóstica. O Consenso de Frankfurt, 1990, estabeleceu critérios histológicos qualitativos para diagnóstico de DNI-B, como hiperganglionose e hiperplasia do plexo nervoso submucoso. Meier-Ruge et al. 2004, 2006, definiu o diagnóstico de maneira quantitativa: mais de 20% de gânglios nervosos gigantes na submucosa, com mais de 8 neurônios cada, em 25 gânglios examinados, e em crianças maiores de 1 ano. Objetivos: Analisar as características morfológicas do sistema nervoso entérico em pacientes com DNI-B segundo os critérios do Consenso de Frankfurt de 1990, e testar a aplicabilidade dos critérios numéricos propostos por Meier-Ruge et al 2004. Pacientes e Métodos: Foram analisadas retrospectivamente peças cirúrgicas de cólon distal de 29 pacientes, com idade de 0 a 16 anos, com diagnóstico de DNI-B, em cortes histológicos processados para histologia convencional pela hematoxilina e eosina (H&E) e para imuno-histoquímica da calretinina. Resultados: Apenas 1 paciente contemplou estes critérios numéricos. Houve imunopositividade para calretinina nos neurônios, porém a contagem de neurônios foi menor em relação ao H&E (p=0,002). Não houve diferenças significa... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Introduction: Intestinal Neuronal Dysplasia type B (INDB) is a gastrointestinal neuromuscular disease characterized by complex changes in the enteric nervous system. The diagnosis depends on the histopathological analysis of rectal biopsies and the diagnostic criteria have changed over the years, making it difficult to diagnostic practice. The Frankfurt Consensus, 1990, established qualitative criteria for the histological diagnosis of INDB, such as gigant ganglia and hyperplasia of submucosal nerves. Meier-Ruge et al. 2004, 2006, defined quantitative criteria: over 20% of giant ganglia, with more than 8 nerve cells each, on 25 ganglia examined, and in children older than one year. Objectives: Analyze the morphological characteristics of the enteric nervous system in patients with INDB according to the Frankfurt Consensus Criteria 1990 and test the applicability of the numerical criteria proposed by Meier-Ruge et al. 2004. Patients and Methods: Surgical specimens of distal colon from 29 patients, aged 0-16 years old, diagnosed with INDB, in histological sections processed for conventional histology by hematoxylin and eosin (H&E) and for immunohistochemistry of calretinin, were retrospectively analyzed. Results: Only one patient met these numerical criteria. There was immunostaining for calretinin in neurons but the neurons count was lower in relation to H&E (p=0.002). There were no significant differences between the age groups of children younger and older than 1 year old in... (Complete abstract click electronic access below) / Mestre

O diabetes mellitus tipo 2 (DM2) é uma doença de prevalência crescente na população mundial, sendo associado ao aumento de diversas comorbidades. A relação entre o trato digestivo e o DM2 tem sido fortalecida a partir dos resultados das diferentes cirurgias metabólicas frente à remissão do distúrbio endócrino. Alterações morfológicas hipertróficas no epitélio intestinal são percebidas nos estágios iniciais da doença e parece ter papel primordial na instalação da hiperglicemia crônica. O gene p53 participa ativamente dos processos de regulação do crescimento epitelial intestinal e pode sofrer alteração de sua expressão em estados diabéticos. Objetiva-se avaliar os resultados clínicos e laboratoriais de pacientes DM2 e com índice de Massa Corpórea (IMC) >25 e <35 Kg/m2 submetidos a cirurgia metabólica denominada adaptação digestiva com duodenal switch parcial (DSP) e avaliar o comportamento da expressão do gene p53 na mucosa intestinal no período pré e pós-operatório. Nove pacientes DM2, com IMC<35Kg/m2 foram operados pela técnica DSP. Biópsias de duodeno e íleo foram colhidas no estado diabético (pré e transoperatório respectivamente) e, 3 meses após a cirurgia, através de endoscopia digestiva alta. Foram comparados os dados de evolução antropométrica (IMC) e laboratorial no período pré e pós-operatório. Através do método enzyme-linked immunosorbent assay (ELISA) foram determinados os níveis dos entero-hormônios glucagon-like peptide-1 (GLP-1) e glucose-dependent insulinotropic peptide (GIP), no pré e pós-operatório, em jejum e pós-prandial nos períodos 30',60',90' e 120'. A expressão do gene p53, foi avaliada por real time polymerase chain reaction (qrt-PCR) e western blot, nos dois diferentes momentos. As variáveis: glicemia de jejum e pós-prandial (2 horas), trigliceridemia de jejum, hemoglobina glicada (HbAc1) e peptídeo C foram analisadas. As médias dos parâmetros laboratoriais foram comparadas pela análise multivariada ANOVA e após teste-Tukey. A média de expressão relativa do gene p53 foi comparada nos dois períodos pelo teste t-student. Os resultados evidenciaram que entre maio e dezembro de 2010, nove pacientes (4 homens, 5 mulheres) DM2 e com IMC entre 26 e 34Kg/m2 foram submetidos a DSP. A média de IMC do grupo operado foi de 31,3. Houve queda do IMC média de 23% após um ano. Houve queda significativa (p<0,05) nos níveis de triglicerídeos, glicemia de jejum e pós-prandial (2 horas), HbA1c assim como aumento do peptídeo-C (p<0,05), quando comparados os períodos pré e pós-operatório. Os níveis séricos de GLP-1 foram significativamente maiores no pós-operatório (p<0,05), tanto em jejum como pós-prandial sendo que houve diminuição dos níveis de GIP, contudo sem significância estatística. O gene p53 sofreu aumento significativo de sua expressão relativa (qrt-PCR)(p<0,05) no período pós-operatório na mucosa duodenal e uma tendência de aumento no íleo, contudo sem significância estatística. A análise da expressão ao nível proteico foi bem sucedida somente no íleo, também mostrando tendência de aumento. Concluí-se que a DSP foi capaz de controlar satisfatoriamente o DM2 em pacientes com IMC<35 Kg/m2. Houve aumento da secreção de GLP-1 e tendência de diminuição do GIP. Houve aumento da expressão do p53 na mucosa intestinal, no período pós-operatório, após o controle do diabetes, quando comparada ao período pré-operatório. / Diabetes mellitus type 2 (DM2) is a worldwide increasing prevalence disease, being related to a variety of comorbidities. The relationship between the digestive tract and DM2 has been strengthened by the results of different metabolic surgery procedures on resolution of the endocrine disorder, before weigh loss achievement. Hypertrophic morphological changes in the intestinal epithelium are observed in the early stages of disease development and seems to have a pivotal role in the establishment of chronic hyperglicemia. The p53 gene directly participates on regulation of growth processes of the intestinal epithelium, and its expression has been shown to be altered in diabetic states.The objectives were to evaluate clinical and laboratory results in DM2 patients, presenting Body Mass Index(BMI)>25 and <35Kg/m2, undergoing a metabolic surgery procedure called digestive adaptation with partial duodenal switch(DSP). To assess p53 gene expression behavior in intestinal mucosa, on pre and postoperative period. Nine patients presenting DM2 and BMI below 35Kg/m2 underwent DSP.Biopsies of the duodenum and intermediate portion of the ileum were undertaken in diabetic state (pre and transoperative respectively) and 3 months after surgery by upper gastrointestinal endoscopy. The evolution of anthropometric (BMI) and laboratory parameters were acessed on postoperative period. Serum levels of enterohormones glucagon-like peptide-1(GLP-1) and glucose-dependent insulinotropic peptide (GIP) were determined by the method enzyme-linked immunosorbent assay (ELISA), pre and postoperatively, on fasting and postprandial state (30',60'90 and 120') after ingestion of a standart meal.The p53 gene expression was evaluated by real time polymerase chain reaction (qrt-PCR) and western blot, on two different periods. The variables: fasting and postprandial (2 hours) glicemia, fasting triglycerides (TG), glycosylated hemoglobin (HbA1c) and C-peptide were undertaken. The mean levels of laboratorial parameters were compared by mulivariate analyses (ANOVA) and Tukey test. The mean expression of the p53 gene was compared in two different periods by T test. Between may and December 2010, four men and 5 women were operated on. The mean BMI was 31,1. There was a decrease in BMI of 23% after one year of surgery. There was a significant decrease (p<0,05) on fasting TG and HbA1c levels as well as glucose levels on fasting and postprandial state (2 hours) when compared pre and postoperatively. There was an increase (p<0,05) in C-peptide levels after surgery. Serum levels of GLP-1 were significantly higher postorperatively (p<0,05), on both fasting and postprandial condition, and there was a decrease,not significant, on GIP levels. The p53 relative gene expression showed a significant increase (p<0,05) in the postoperative period in duodenal mucosa (transcriptional state) and showed an increasing trend in the ileum, but not statistically significant. Only ileum portion results were succesfully acessed by western blot analisys, showing an increasing trend as well. The DSP procedure was succesfully capable to control type 2 diabetes in patients presenting BMI<35 Kg/m2. There was a significant enhancement of GLP-1 secretion and a decreasing trend for GIP on postoperative period. There was increased expression of mucosal p53 in the postoperative period after the control of DM2, when compared to diabetic pre-operative state.

Call number: LD2668 .T4 1957 B46 / Master of Science

Single Nucleotide Polymorphisms (SNPs) in the intracellular pattern recognition receptor gene NLRP3 are associated with susceptibility to Crohn’s disease, a form of inflammatory bowel disease (IBD). Following cell damage or infection, NLRP3 triggers the formation of inflammasomes, a multimolecular protein complex containing NLRP3, ASC and caspase-1, which mediate secretion of IL-1β and IL-18. NLRP3 inflammasome activation in macrophages has been implicated in protection against several pathogens, but whether NLRP3 activation in tissue cells contributes to protective immunity against bacterial pathogens is unknown. We show that upon infection with the attaching/effacing (A/E) intestinal pathogen Citrobacter rodentium, Nlrp3-/- and Asc-/- mice displayed higher bacterial colonization, more weight loss and exacerbated intestinal inflammation. We further show that Nlrp3 inflammasome activation in intestinal epithelial cells (IECs) acts rapidly after infection to limit bacterial replication and penetration, and inhibits the development of inflammatory pathology in the gut. We also show that epithelial Nlrp3-mediated protection is independent of the classical inflammasome cytokines IL-1β and IL-18. Thus an Nlrp3-Asc circuit in IECs regulates early defense against a mucosal pathogen and limits inflammation in the intestine. Nlrp3 inflammasome activation has also been implicated in protection in acute models of experimental colitis, but its role in chronic models of colitis is unknown. We found that Asc signaling is necessary for the development of innate chronic intestinal inflammation driven by Helicobacter hepaticus. Thus while deficient inflammasome signaling in tissue cells increases susceptibility towards enteric pathogens, excessive inflammasome activation can drive chronic intestinal inflammation.

published_or_final_version / Zoology / Master / Master of Philosophy

No description available.

Neonatal necrotizing enterocolitis (NEC) is the most common gastrointestinal disease in premature babies. Despite significant morbidity and mortality, the cause of this disease remains unclear and there are no preventative treatments available. Prematurity and enteral feeding of infant formula are considered to be the primary risk factors for development of NEC. Interestingly, the incidence of NEC is six to ten times lower in breast-fed babies compared to those that were formula-fed. The factors responsible for the protective effect of breast milk against NEC have not been identified, but epidermal growth factor (EGF) is one of the most promising candidates. EGF is found at high concentrations in human milk, but is not present in any commercial formula. Mothers with extremely premature babies have 50-80% higher levels of EGF in their breast milk compared to mothers with full term infants. This suggests that EGF plays an important role in the development of premature infants. Our studies have shown that supplementation of EGF into formula significantly reduces the incidence of NEC in a neonatal rat model. However, the mechanisms underlying this EGF-mediated reduction of NEC are not understood. The overall hypothesis of this dissertation is that the protective effect of EGF in NEC pathogenesis is mediated via increased expression of pro-survival genes and strengthening of the mucosal barrier. The results of the studies within this dissertation demonstrate that treatment with EGF significantly decreases intestinal epithelial cell apoptosis at the site of NEC injury by up-regulating anti-apoptotic genes and down-regulating pro-apoptotic genes. Furthermore, supplementation of formula with EGF strengthens the mucosal barrier by inducing accelerated maturation of ileal goblet cells and mucin-2 production. In addition, EGF treatment normalizes expression of crucial tight junction proteins in the ileum. Consequently, EGF treatment results in a significant decrease in intestinal paracellular permeability and improved barrier function. Results from these studies will provide significant contributions to the understanding of EGF-mediated reduction of NEC, which may lead to development of therapeutic strategies for the treatment of human NEC.