Inhibition of nuclear factor-kappaB ameliorates bowel injury and prolongs survival in a neonatal rat model of necrotizing enterocolitis

The NF-κB signaling system in the immunopathogenesis of inflammatory bowel disease

Inflammatory bowel disease (IBD) is an idiopathic, chronic condition characterized by episodes of inflammation in the gastrointestinal tract. The nuclear factor κB (NF-κB) system describes a family of dimeric transcription factors. Canonical NF-κB signaling is stimulated by and enhances inflammation, whereas noncanonical NF-κB signaling contributes to immune organogenesis. Dysregulation of NF-κB factors drives various inflammatory pathologies, including IBD. Signals from many immune sensors activate NF-κB subunits in the intestine, which maintain an equilibrium between local microbiota and host responses. Genetic association studies of patients with IBD and preclinical mouse models confirm the importance of the NF-κB system in host defense in the gut. Other studies have investigated the roles of these factors in intestinal barrier function and in inflammatory gut pathologies associated with IBD. NF-κB signaling modulates innate and adaptive immune responses and the production of immunoregulatory proteins, anti-inflammatory cytokines, antimicrobial peptides, and other tolerogenic factors in the intestine. Furthermore, genetic studies have revealed critical cell type-specific roles for NF-κB proteins in intestinal immune homeostasis, inflammation, and restitution that contribute to the etiopathology of IBD-associated manifestations. Here, we summarize our knowledge of the roles of these NF-κB pathways, which are activated in different intestinal cell types by specific ligands, and their cross-talk, in fueling aberrant intestinal inflammation. We argue that an in-depth understanding of aberrant immune signaling mechanisms may hold the key to identifying predictive or prognostic biomarkers and developing better therapeutics against inflammatory gut pathologies.

Clostridium scindens exacerbates experimental necrotizing enterocolitis via upregulation of the apical sodium-dependent bile acid transporter

Necrotizing enterocolitis (NEC) is the most common gastrointestinal emergency in premature infants. Evidence indicates that bile acid homeostasis is disrupted during NEC: ileal bile acid levels are elevated in animals with experimental NEC, as is expression of the apical sodium-dependent bile acid transporter (Asbt). In addition, bile acids, which are synthesized in the liver, are extensively modified by the gut microbiome, including via the conversion of primary bile acids to more cytotoxic secondary forms. We hypothesized that the addition of bile acid-modifying bacteria would increase susceptibility to NEC in a neonatal rat model of the disease. The secondary bile acid-producing species Clostridium scindens exacerbated both incidence and severity of NEC. C. scindens upregulated the bile acid transporter Asbt and increased levels of intraenterocyte bile acids. Treatment with C. scindens also altered bile acid profiles and increased hydrophobicity of the ileal intracellular bile acid pool. The ability of C. scindens to enhance NEC requires bile acids, as pharmacological sequestration of ileal bile acids protects animals from developing disease. These findings indicate that bile acid-modifying bacteria can contribute to NEC pathology and provide additional evidence for the role of bile acids in the pathophysiology of experimental NEC.NEW & NOTEWORTHY Necrotizing enterocolitis (NEC), a life-threatening gastrointestinal emergency in premature infants, is characterized by dysregulation of bile acid homeostasis. We demonstrate that administering the secondary bile acid-producing bacterium Clostridium scindens enhances NEC in a neonatal rat model of the disease. C. scindens-enhanced NEC is dependent on bile acids and driven by upregulation of the ileal bile acid transporter Asbt. This is the first report of bile acid-modifying bacteria exacerbating experimental NEC pathology.

New insights into intestinal macrophages in necrotizing enterocolitis: the multi-functional role and promising therapeutic application

Necrotizing enterocolitis (NEC) is an inflammatory intestinal disease that profoundly affects preterm infants. Currently, the pathogenesis of NEC remains controversial, resulting in limited treatment strategies. The preterm infants are thought to be susceptible to gut inflammatory disorders because of their immature immune system. In early life, intestinal macrophages (IMφs), crucial components of innate immunity, demonstrate functional plasticity and diversity in intestinal development, resistance to pathogens, maintenance of the intestinal barrier, and regulation of gut microbiota. When the stimulations of environmental, dietary, and bacterial factors interrupt the homeostatic processes of IMφs, they will lead to intestinal disease, such as NEC. This review focuses on the IMφs related pathogenesis in NEC, discusses the multi-functional roles and relevant molecular mechanisms of IMφs in preterm infants, and explores promising therapeutic application for NEC.

State-of-the-art review and update of in vivo models of necrotizing enterocolitis

NEC remains one of the most common causes of mortality and morbidity in preterm infants. Animal models of necrotizing enterocolitis (NEC) have been crucial in improving our understanding of this devastating disease and identifying biochemical pathways with therapeutic potential. The pathogenesis of NEC remains incompletely understood, with no specific entity that unifies all infants that develop NEC. Therefore, investigators rely on animal models to manipulate variables and provide a means to test interventions, making them valuable tools to enhance our understanding and prevent and treat NEC. The advancements in molecular analytic tools, genetic manipulation, and imaging modalities and the emergence of scientific collaborations have given rise to unique perspectives and disease correlates, creating novel pathways of investigation. A critical review and understanding of the current phenotypic considerations of the highly relevant animal models of NEC are crucial to developing novel therapeutic and preventative strategies for NEC.

The benefits, limitations and opportunities of preclinical models for neonatal drug development

Increased research to improve preclinical models to inform the development of therapeutics for neonatal diseases is an area of great need. This article reviews five common neonatal diseases – bronchopulmonary dysplasia, retinopathy of prematurity, necrotizing enterocolitis, perinatal hypoxic–ischemic encephalopathy and neonatal sepsis – and the available in vivo, in vitro and in silico preclinical models for studying these diseases. Better understanding of the strengths and weaknesses of specialized neonatal disease models will help to improve their utility, may add to the understanding of the mode of action and efficacy of a therapeutic, and/or may improve the understanding of the disease pathology to aid in identification of new therapeutic targets. Although the diseases covered in this article are diverse and require specific approaches, several high-level, overarching key lessons can be learned by evaluating the strengths, weaknesses and gaps in the available models. This Review is intended to help guide current and future researchers toward successful development of therapeutics in these areas of high unmet medical need.

Summary: This article reviews and analyzes the available preclinical models for five common neonatal diseases to direct therapeutic development in these areas of high unmet medical need.

Intestinal Epithelial Barrier Function and Necrotizing Enterocolitis

Necrotizing enterocolitis (NEC) is a major cause of morbidity and mortality in premature infants. NEC is characterized by intestinal tissue inflammation and necrosis. The intestinal barrier is altered in NEC, which potentially contributes to its pathogenesis by promoting intestinal bacterial translocation and stimulating the inflammatory response. In premature infants, many components of the intestinal barrier are immature. This article reviews the different components of the intestinal barrier and how their immaturity contributes to intestinal barrier dysfunction and NEC.

Single Nucleotide Polymorphisms in Neonatal Necrotizing Enterocolitis

The etiopathogenesis of necrotizing enterocolitis (NEC) remains unclear, but increasing information suggests that the risk and severity of NEC may be influenced by single nucleotide polymorphisms in many genes. In this article, we have reviewed gene variations that have either been specifically identified in NEC or have been noted in other inflammatory bowel disorders with similar histopathological abnormalities. We present evidence from our own peer-reviewed laboratory studies and data from an extensive literature search in the databases PubMed, EMBASE, and Scopus. To avoid bias in the identification of existing studies, search keywords were short-listed both from our own studies and from PubMed's Medical Subject Heading (MeSH) thesaurus.

Necrotizing Enterocolitis: Clinical Features, Histopathological Characteristics, and Genetic Associations

Necrotizing enterocolitis (NEC) is an inflammatory bowel necrosis seen in premature infants. Although the etiopathogenesis of NEC is unclear, genetic factors may alter a patient's susceptibility, clinical course, and outcomes. This review draws from existing studies focused on individual genes and others based on microarray-based high-throughput discovery techniques. We have included evidence from our own studies and from an extensive literature search in the databases PubMed, EMBASE, and Scopus. To avoid bias in the identification of studies, keywords were short-listed a priori from anecdotal experience and PubMed's Medical Subject Heading (MeSH) thesaurus.

The Impact of MicroRNAs in Neonatal Necrotizing Enterocolitis and other Inflammatory Conditions of Intestine: A Review

The understanding of necrotizing enterocolitis (NEC) etiopathogenesis is incomplete, contributing to the lack of early biomarkers and therapeutic options. Micro RNAs (miRNAs) are a class of RNAs that can alter gene expression and modulate various physiological and pathological processes. Several studies have been performed to evaluate the role of miRNA in the pathogenesis of NEC. In this article, we review the information on miRNAs that have been specifically identified in NEC or have been noted in other inflammatory bowel disorders that share some of the histopathological abnormalities seen frequently in NEC. This review highlights miRNAs that could be useful as early biomarkers of NEC and suggests possible approaches for future translational studies focused on these analytes. It is a novel field with potential for immense translational and clinical relevance in preventing, detecting, or treating NEC in very premature infants. Impact • Current information categorizes necrotizing enterocolitis (NEC) as a multifactorial disease, but microRNAs (miRNAs) may influence the risk of occurrence of NEC. • MiRNAs may alter the severity of the intestinal injury and the clinical outcome of NEC. • The literature on intestinal diseases of adults suggests additional miRNAs that have not been studied in NEC yet but share some features and deserve further exploration in human NEC, especially if affecting gut dysbiosis, intestinal perfusion, and coagulation disorders.

Urine-derived extracellular vesicle miRNAs as possible biomarkers for and mediators of necrotizing enterocolitis: A proof of concept study

BACKGROUND

Early-stage symptomology of necrotizing enterocolitis (NEC) is similar in presentation to non-NEC sepsis, though the treatment plans differ based on antibiotic administration and withholding of feeds. Improved diagnostics for NEC differentiation would allow clinicians to more rapidly set individual patients on a targeted treatment path. Extracellular vesicle-derived miRNAs, have previously demonstrated efficacy as disease biomarkers. To determine if these miRNAs are differentially-expressed in NEC infants, we performed transcriptomic analysis of urine-derived extracellular vesicle-derived miRNAs.

METHODS

Urine was non-invasively obtained from infants in one of four groups (n ≥ 8) (Medical NEC, Surgical NEC, non-NEC sepsis, and healthy age-matched controls). EV-derived miRNAs were isolated and transcriptomic analysis was performed.

RESULTS

Multiple miRNAs, including miR-376a, miR-518a-3p and miR-604, were significantly altered when comparing NEC to non-NEC sepsis and healthy controls, and could potentially be used as specific NEC biomarkers. Additionally, Ingenuity Pathway Analysis demonstrated that miRs differentially-expressed in NEC were associated with inflammatory disease and intestinal disease. Signal transduction molecules associated with NEC including TP53 and RPS15, which were also reduced transcriptionally in a rat model of NEC.

CONCLUSION

These data indicate that there is a pool of potential urine EV-derived miRNAs that may be validated as NEC biomarkers in the differentiation of NEC from non-NEC sepsis and from age-matched controls. Additionally, signal transduction molecules associated with miRNAs differentially-expressed in human NEC are altered in a murine model of NEC, suggesting potential crossover between murine models of the disease and actual human presentation.

LEVEL OF EVIDENCE

Level III Study of Diagnostic Test.

The miR-223/nuclear factor I-A axis regulates inflammation and cellular functions in intestinal tissues with necrotizing enterocolitis

We previously demonstrated that microRNA(miR)‐223 is overexpressed in intestinal tissue of infants with necrotizing enterocolitis (NEC). The objective of the current study was to identify the target gene of miR‐223 and to investigate the role of the miR‐223/nuclear factor I‐A (NFIA) axis in cellular functions that underpin the pathophysiology of NEC. The target gene of miR‐223 was identified by in silico target prediction bioinformatics, luciferase assay, and western blotting. We investigated downstream signals of miR‐223 and cellular functions by overexpressing the miRNA in Caco‐2 and FHs74 cells stimulated with lipopolysaccharide or lipoteichoic acid (LTA). NFIA was identified as a target gene of miR‐223. Overexpression of miR‐223 significantly induced MYOM1 and inhibited NFIA and RGN in Caco‐2 cells, while costimulation with LTA decreased expression of GNA11, MYLK, and PRKCZ. Expression levels of GNA11, MYLK, IL‐6, and IL‐8 were increased, and levels of NFIA and RGN were decreased in FHs74 cells. These potential downstream genes were significantly correlated with levels of miR‐223 or NFIA in primary NEC tissues. Overexpression of miR‐223 significantly increased apoptosis of Caco‐2 and FHs74 cells, while proliferation of FHs74 was inhibited. These results suggest that upon binding with NFIA, miR‐223 regulates functional effectors in pathways of apoptosis, cell proliferation, G protein signaling, inflammation, and smooth muscle contraction. The miR‐223/NFIA axis may play an important role in the pathophysiology of NEC by enhancing inflammation and tissue damage.

Immunization with anti-Tn immunogen in maternal rats protects against hyperoxia-induced kidney injury in newborn offspring

BACKGROUND

Neonatal hyperoxia increases oxidative stress and adversely disturbs glomerular and tubular maturity. Maternal Tn immunization induces anti-Tn antibody titer and attenuates hyperoxia-induced lung injury in neonatal rats.

METHODS

We intraperitoneally immunized female Sprague-Dawley rats (6 weeks old) with Tn immunogen (50 μg/dose) or carrier protein five times at biweekly intervals on 8, 6, 4, 2, and 0 weeks before the delivery day. The pups were reared for 2 weeks in either room air (RA) or in 85% oxygen-enriched atmosphere (O₂), thus generating four study groups, namely carrier protein + RA, Tn vaccine + RA, carrier protein + O₂, and Tn vaccine + O₂. On postnatal day 14, the kidneys were harvested for the oxidative stress marker 8-hydroxy-2'-deoxyguanosine (8-OHdG), nuclear factor-κB (NF-κB), and collagen expression and histological analyses.

RESULTS

Hyperoxia reduced body weight, induced tubular and glomerular injuries, and increased 8-OHdG and NF-κB expression and collagen deposition in the kidneys. By contrast, maternal Tn immunization reduced kidney injury and collagen deposition in neonatal rats. Furthermore, kidney injury attenuation was accompanied by a reduction in 8-OHdG and NF-κB expression.

CONCLUSION

Maternal Tn immunization protects against hyperoxia-induced kidney injury in neonatal rats by attenuating oxidative stress and NF-κB activity.

IMPACT

Hyperoxia increased nuclear factor-κB (NF-κB) activity and collagen deposition in neonatal rat kidney. Maternal Tn immunization reduced kidney injury as well as collagen deposition in neonatal rats. Maternal Tn immunization reduced kidney injury and was associated with a reduction in 8-hydroxy-2'-deoxyguanosine and NF-κB activity. Tn vaccine can be a promising treatment modality against hyperoxia-induced kidney injury in neonates.

Necrotizing Enterocolitis: LPS/TLR4-Induced Crosstalk Between Canonical TGF-β/Wnt/β-Catenin Pathways and PPARγ

Necrotizing enterocolitis (NEC) represents one of the major causes of morbidity and mortality in premature infants. Several recent studies, however, have contributed to a better understanding of the pathophysiology of this dreadful disease. Numerous intracellular pathways play a key role in NEC, namely: bacterial lipopolysaccharide (LPS), LPS toll-like receptor 4 (TLR4), canonical Wnt/β-catenin signaling and PPARγ. In a large number of pathologies, canonical Wnt/β-catenin signaling and PPARγ operate in opposition to one another, so that when one of the two pathways is overexpressed the other is downregulated and vice-versa. In NEC, activation of TLR4 by LPS leads to downregulation of the canonical Wnt/β-catenin signaling and upregulation of PPARγ. This review aims to shed light on the complex intracellular mechanisms involved in this pathophysiological profile by examining additional pathways such as the GSK-3β, NF-κB, TGF-β/Smads, and PI3K-Akt pathways.

Hydrogen Promotes the M1 Macrophage Conversion During the Polarization of Macrophages in Necrotizing Enterocolitis

Background: Hydrogen is protective against intestinal injury in necrotizing enterocolitis (NEC), mainly through to alleviate inflammation response. The M1 macrophages can promote inflammation. We hypothesized that hydrogen would promote the M1 macrophages conversion during the polarization and reduce the inflammatory factors in NEC. Methods: We used M1 and M2 macrophages induced from RAW264.7 cells and bone marrow-derived macrophages, models of NEC and macrophages derived from spleens, abdominal lymph nodes and lamina propria in model mice. Cytokines, CD16/32 and CD206 were measured by quantitative PCR, flow cytometry. Nuclear factor-κB (NF-κB) p65 were determined by western blot. Histology staining were used to assess the severity of NEC. Results: Macrophages were successfully polarized to M1 or M2 by assessing the expression of inflammatory factors. Pro-inflammatory factors and CD16/32 in M1 macrophages were decreased, and the expression of CD16/32 in lamina propria were inhibited after treatment with hydrogen, but the changes has no effects in other tissues. Hydrogen inhibited the NF-κB p65 in M1 macrophages nucleus and distal ileum of NEC. HE staining showed hydrogen could attenuate the severity of NEC. Conclusion: Hydrogen could attenuate the severity of NEC through promoting M1 macrophages conversion by inhibited the expression of NF-κB p65 in the nucleus.

Peptidomics Analysis Discloses That Novel Bioactive Peptides Participate in Necrotizing Enterocolitis in a Rat Model

Necrotizing enterocolitis (NEC) is a common devastating gastrointestinal disease in premature infants, the molecular mechanisms of which have not been fully elucidated. Recently, endogenous peptides have garnered much attention owing to their role in diagnosis and treatment. However, changes in the peptide expression of NEC intestinal tissues remain poorly understood. In the present study, a comparative peptidomics profiling analysis was performed between NEC and control intestinal tissues via liquid chromatography-tandem mass spectrometry (LC-MS). In total, 103 upregulated and 73 downregulated peptides were identified in the intestinal tissues (fold change ≥ 1.5, p < 0.05). Bioinformatics analysis revealed that these differentially expressed peptides were significantly associated with NEC pathophysiology, including apoptosis, the TGF-β signaling pathway, the Wnt signaling pathway, and the MAPK signaling pathway. Furthermore, two putative peptides could inhibit apoptosis and promote the migration of intestinal epithelial cells induced by lipopolysaccharide; these peptides were derived from the protein domains MT1 and EZRI, respectively. In conclusion, our study revealed that endogenous peptides are involved in the pathophysiologic mechanism of NEC; nevertheless, further exploration is required in this regard.

The Role of Glycosaminoglycans in Protection from Neonatal Necrotizing Enterocolitis: A Narrative Review

Necrotizing enterocolitis, a potentially fatal intestinal inflammatory disorder affecting primarily premature infants, is a significant cause of morbidity and mortality in neonates. While the etiology of the disease is, as yet, unknown, a number of risk factors for the development of necrotizing enterocolitis have been identified. One such risk factor, formula feeding, has been shown to contribute to both increased incidence and severity of the disease. The protective influences afforded by breastfeeding are likely attributable to the unique composition of human milk, an extremely potent, biologically active fluid. This review brings together knowledge on the pathogenesis of necrotizing enterocolitis and current thinking on the instrumental role of one of the more prominent classes of bioactive components in human breast milk, glycosaminoglycans.

Breast Milk Lipids and Fatty Acids in Regulating Neonatal Intestinal Development and Protecting against Intestinal Injury

Human breast milk is the optimal source of nutrition for infant growth and development. Breast milk fats and their downstream derivatives of fatty acids and fatty acid-derived terminal mediators not only provide an energy source but also are important regulators of development, immune function, and metabolism. The composition of the lipids and fatty acids determines the nutritional and physicochemical properties of human milk fat. Essential fatty acids, including long-chain polyunsaturated fatty acids (LCPUFAs) and specialized pro-resolving mediators, are critical for growth, organogenesis, and regulation of inflammation. Combined data including in vitro, in vivo, and human cohort studies support the beneficial effects of human breast milk in intestinal development and in reducing the risk of intestinal injury. Human milk has been shown to reduce the occurrence of necrotizing enterocolitis (NEC), a common gastrointestinal disease in preterm infants. Preterm infants fed human breast milk are less likely to develop NEC compared to preterm infants receiving infant formula. Intestinal development and its physiological functions are highly adaptive to changes in nutritional status influencing the susceptibility towards intestinal injury in response to pathological challenges. In this review, we focus on lipids and fatty acids present in breast milk and their impact on neonatal gut development and the risk of disease.

Necrotizing enterocolitis: It's not all in the gut

Necrotizing enterocolitis is the leading cause of death due to gastrointestinal disease in preterm neonates, affecting 5–12% of neonates born at a very-low birth weight. Necrotizing enterocolitis can present with a slow and insidious onset, with some neonates displaying early symptoms such as feeding intolerance. Treatment during the early stages includes bowel rest and careful use of antibiotics, but surgery is required if pneumoperitoneum and intestinal perforation occur. Mortality rates among neonates requiring surgery are estimated to be 20–30%, mandating the development of non-invasive and reliable biomarkers to predict necrotizing enterocolitis before the onset of clinical signs. Such biomarkers would allow at-risk neonates to receive maximal preventative therapies such as careful nutritional consideration, probiotics, and increased skin-to-skin care.

Impact statement

Necrotizing enterocolitis (NEC) is a devastating gastrointestinal disease; its high mortality rate mandates the development of non-invasive biomarkers to predict NEC before its onset. This review summarizes the pathogenesis, prevention, unresolved issues, and long-term outcomes of NEC.

trans-Cinnamaldehyde mitigated intestinal inflammation induced by Cronobacter sakazakii in newborn mice

Necrotizing enterocolitis (NEC) is a serious intestinal disease associated with a high mortality (40-60%) in newborn infants. Cronobacter sakazakii is an important factor for NEC. However, studies regarding NEC pathogenesis and therapeutic treatments are still limited. Here, a C. sakazakii-induced mouse neonatal intestinal inflammation model was employed to determine the effects of trans-cinnamaldehyde (TC) on infections. TC treatment reduced the number of C. sakazakii colony-forming units in the ileal tissues and mitigated the morphological damage in intestinal tissues. Additionally, it reduced the mRNA transcription of inflammatory genes and production of interleukin 6 and tumor necrosis factor-α in mice infected with C. sakazakii. Moreover, TC treatment suppressed caspase-3 activity, modulated enterocyte apoptosis, and inhibited the nuclear factor-kappa B signaling pathway activation induced by C. sakazakii. These findings suggest that TC has protective effects on C. sakazakii-induced murine intestinal inflammation and that it may be a potential agent for preventing NEC.

Curcumin and Intestinal Inflammatory Diseases: Molecular Mechanisms of Protection

Intestinal inflammatory diseases, such as Crohn’s disease, ulcerative colitis, and necrotizing enterocolitis, are becoming increasingly prevalent. While knowledge of the pathogenesis of these related diseases is currently incomplete, each of these conditions is thought to involve a dysfunctional, or overstated, host immunological response to both bacteria and dietary antigens, resulting in unchecked intestinal inflammation and, often, alterations in the intestinal microbiome. This inflammation can result in an impaired intestinal barrier allowing for bacterial translocation, potentially resulting in systemic inflammation and, in severe cases, sepsis. Chronic inflammation of this nature, in the case of inflammatory bowel disease, can even spur cancer growth in the longer-term. Recent research has indicated certain natural products with anti-inflammatory properties, such as curcumin, can help tame the inflammation involved in intestinal inflammatory diseases, thus improving intestinal barrier function, and potentially, clinical outcomes. In this review, we explore the potential therapeutic properties of curcumin on intestinal inflammatory diseases, including its antimicrobial and immunomodulatory properties, as well as its potential to alter the intestinal microbiome. Curcumin may play a significant role in intestinal inflammatory disease treatment in the future, particularly as an adjuvant therapy.

Blocking NF-κB Activation in Ly6c+ Monocytes Attenuates Necrotizing Enterocolitis

Necrotizing enterocolitis (NEC) is a devastating disease affecting premature infants with intestinal inflammation and necrosis. The neonatal intestinal inflammatory response is rich in macrophages, and blood monocyte count is low in human NEC. We previously found that NF-κB mediates the intestinal injury in experimental NEC. However, the role of NF-κB in myeloid cells during NEC remains unclear. Herein, inhibitor of kappaB kinase β (IKKβ), a critical kinase mediating NF-κB activation, was deleted in lysozyme M (Lysm)-expressing cells, which were found to be Cd11b+Ly6c+ monocytes but not Cd11b+Ly6c- macrophages in the dam-fed neonatal mouse intestine. NEC induced differentiation of monocytes into intestinal macrophages and up-regulation of monocyte recruitment genes (eg, L-selectin) in the macrophage compartment in wild-type mice, but not in pups with IKKβ deletion in Lysm+ cells. Thus, NF-κB is required for NEC-induced monocyte activation, recruitment, and differentiation in neonatal intestines. Furthermore, pups with Lysm-IKKβ deletion had improved survival and decreased incidence of severe NEC compared with littermate controls. Decreased NEC severity was not associated with an improved intestinal barrier. In contrast, NEC was unabated in mice with IKKβ deletion in intestinal epithelial cells. Together, these data suggest that recruitment of Ly6c+ monocytes into the intestine, NF-κB activation in these cells, and differentiation of Ly6c+ monocytes into macrophages are critical cellular and molecular events in NEC development to promote disease.

Milk Fat Globule Membrane Ameliorates Necrotizing Enterocolitis in Neonatal Rats and Suppresses Lipopolysaccharide-Induced Inflammatory Response in IEC-6 Enterocytes

BACKGROUND

Evidence has provided support for the beneficial effects of milk fat globule membrane (MFGM) on inflammation in the intestinal tract. The objective of this study was to investigate the effects of MFGM on a rat model of necrotizing enterocolitis (NEC) and its potential mechanism of action.

METHODS

Sixty-two newborn Sprague Dawley rats were randomly divided into 4 experimental groups: Breast-fed normal, formula fed (FF), FF + 6 g/L MFGM, and FF + 12 g/L MFGM. The FF rats and the FF rats supplemented with MFGM were exposed to asphyxia/cold stress to induce NEC. Body weight, histological score, survival time, oxidative stress injury, enterocyte proliferation/apoptosis, and inflammatory response were assessed. Meanwhile, lipopolysaccharide (LPS)-stimulated IEC-6 enterocytes were used as a model to test the anti-inflammatory effects of MFGM.

RESULTS

Supplementation with 12 g/L MFGM alleviated body weight loss, reduced the incidence of NEC, increased the survival rate, and attenuated the severity of bowel damage in the NEC rat model. Furthermore, 12 g/L MFGM administration inhibited the protein expression of toll-like receptor 4 (TLR4) in the animal model. In IEC-6 enterocytes, the upregulation of TLR4, myeloid differentiation primary response gene 88 (MyD88), phosphorylated nuclear factor-κB (NF-κB) p65 subunit, and the nuclear translocation of NF-κBp65 induced by LPS was partially inhibited by MFGM pretreatment.

CONCLUSION

Our findings suggested that MFGM has beneficial effects on neonatal rats with NEC by suppressing inflammation via the TLR4/MyD88/NF-κB pathway.

Pathophysiology of Necrotizing Enterocolitis: An Update

NEC is a devastating disease that, once present, is very difficult to treat. In the absence of an etiologic treatment, preventive measures are required. Advances in decoding the pathophysiology of NEC are being made but a more comprehensive understanding is needed for the targeting of preventative strategies. A better definition of the disease as well as diagnostic criteria are needed to be able to specifically label a disease as NEC. Multiple environmental factors combined with host susceptibility appear to contribute to enhanced risks for developing this disease. Several different proximal pathways are involved, all leading to a common undesired outcome: Intestinal necrosis. The most common form of this disease appears to involve inflammatory pathways that are closely meshed with the intestinal microbiota, where a dysbiosis may result in dysregulated inflammation. The organisms present in the intestinal tract prior to the onset of NEC along with their diversity and functional capabilities are just beginning to be understood. Fulfillment of postulates that support causality for particular microorganisms is needed if bacteriotherapies are to be intelligently applied for the prevention of NEC. Identification of molecular effector pathways that propagate inflammation, understanding of, even incipient role of genetic predisposition and of miRNAs may help solve the puzzle of this disease and may bring the researchers closer to finding a treatment. Despite recent progress, multiple limitations of the current animal models, difficulties related to studies in humans, along with the lack of a "clear" definition will continue to make it a very challenging disease to decipher.

Genetic predisposition to necrotizing enterocolitis in premature infants: Current knowledge, challenges, and future directions

The role of genetics in the pathogenesis of necrotizing enterocolitis (NEC) was initially informed by epidemiological data indicating differences in prevalence among different ethnic groups as well as concordance in twins. These early observations, together with major advances in genomic research, paved the way for studies that begin to reveal the contribution of genetics to NEC. Using the candidate gene or pathway approach, several potential pathogenic variants for NEC in premature infants have already been identified. More recently, genome-wide association studies and exome-sequencing based studies for NEC have been reported. These advances, however, are tempered by the lack of adequately powered replication cohorts to validate the accuracy of these discoveries. Despite many challenges, genetic research in NEC is expected to increase, providing new insights into its pathogenesis and bringing the promise of personalized care closer to reality. In this review we provide a summary of genetic studies in NEC along with defining the challenges and possible future approaches.

[Relationship between vitamin D deficiency and necrotizing enterocolitis in preterm infants]

OBJECTIVE

To evaluate the relationship of vitamin D level with the development of necrotizing enterocolitis (NEC) in preterm infants.

METHODS

A total of 429 preterm infants with a gestational age of <36 weeks, who were admitted to the department of neonatology within 2 hours after birth between January and December, 2016, were enrolled in the study. According to whether these infants developed NEC, the 429 subjects were divided into NEC group (n=22) and non-NEC group (n=407). Peripheral venous blood was collected from these preterm infants and their mothers at admission to measure the level of 25-hydroxyvitamin D (25-OHD). The two groups were compared in terms of the serum 25-OHD levels of preterm infants and their mothers. Pearson correlation analysis was used to investigate the correlation between the serum 25-OHD levels of preterm infants and their mothers. The distribution of vitamin D levels in preterm infants was compared between the two groups. The univariate logistic regression analysis was used to determine the risk factors for NEC in preterm infants.

RESULTS

The serum 25-OHD levels of preterm infants and their mothers in the NEC group were significantly lower than in the non-NEC group (P<0.001). In both groups, the serum 25-OHD levels of mothers and preterm infants were positively correlated with each other (P<0.001). The distribution of vitamin D levels (normal vitamin D level, low vitamin D level, vitamin D deficiency, and severe vitamin D deficiency) was significantly different between the NEC and non-NEC groups (P<0.001). The univariate logistic regression analysis showed that gestational age, birth weight, 25-OHD levels of preterm infants and their mothers, the duration of mechanical ventilation, the duration of oxygen inhalation, and the length of hospital stay were associated with the development of NEC (P<0.05).

CONCLUSIONS

The serum 25-OHD levels of preterm infants and their mothers may be related to the development of NEC in preterm infants, suggesting that vitamin D supplementation during pregnancy is important for preventing the development of NEC in preterm infants.

New insights on the modulatory roles of metformin or alpha-lipoic acid versus their combination in dextran sulfate sodium-induced chronic colitis in rats

BACKGROUND

Dextran sulfate sodium (DSS)-induced colitis is the most widely used model that resembles ulcerative colitis (UC) in human with challenging chronic mechanistic oxidative stress-inflammatory/immunological cascades. In models of acute colitis, reduction of oxidative stress and inflammatory burdens beside manipulation of many transcriptional factors were achieved by metformin or alpha-lipoic acid (α-LA). Currently, in vivo DSS-induced chronic colitis was conducted and the possible therapeutic roles of metformin and/or α-LA were explored.

METHODS

Chronic UC was induced by adding 5% DSS orally in drinking water for 7days followed by 3% DSS in drinking water for 14days in adult male albino Wistar rats. Intraperitoneal administration of α-LA (25mg/kg, twice/day) and/or metformin (100mg/kg/day) were set at day 7 of DSS administration and continued for 14days. Body weights, survival rates, disease activity index (DAI), colonic oxidative stress markers, tumor necrosis factor (TNF)-α levels, colonic nuclear factor-kappa-B (NF-κB) immunohistochemical expression, and the colonic histopathological changes were observed.

RESULTS

Metformin or/and α-LA attenuated the severity of the DSS-induced colitis through improving the reductions in body weights, the DAI, the colonic oxidative stress markers, TNF-α, and NF-κB levels, and the morphological mucosal damage scores. Significant synergetic therapeutic effects were observed with combined therapeutic regimens.

CONCLUSION

Therapeutically, metformin and α-LA could be administered in chronic colitis. The combination of currently used pharmaceutics with natural and synthetic potent antioxidant compounds will become a therapeutic strategy of choice for UC to improve the quality of life if sufficient clinical trials are available.

Maternal/neonatal vitamin D deficiency: a new risk factor for necrotizing enterocolitis in preterm infants?

OBJECTIVE

The objective of the study was to investigate the possible association between maternal/neonatal 25-hydroxy vitamin D (25-OHD) levels and development of necrotizing enterocolitis (NEC).

STUDY DESIGN

One hundred and forty-five preterm infants ⩽36 weeks of gestation were enrolled. 25-OHD levels were determined in maternal/neonatal blood samples that were obtained at the time of admission to the neonatal intensive care unit.

RESULTS

Of the 145 enrolled patients, 26 (18%) developed NEC. Maternal/neonatal 25-OHD levels in the NEC group were significantly lower than those of the no-NEC group (P=0.001 and 0.004, respectively). In univariate logistic regression analysis, both maternal/neonatal vitamin D levels were a significant predictor of NEC (odds ratio (OR): 0.92 and 0.89; P<0.001 and P<0.005, respectively). However, multivariate logistic regression analysis revealed that only maternal vitamin D level was a significant predictor of NEC (OR: 0.86, P<0.0009).

CONCLUSION

This is the first study to propose a possible association between maternal/neonatal 25-OHD levels and subsequent development of NEC in preterm infants.

Genetic alterations in necrotizing enterocolitis

An underlying genetic predisposition to necrotizing enterocolitis (NEC) is increasingly being recognized. Candidate gene or pathway approaches as well as genome-wide approaches are beginning to identify potential pathogenic variants for NEC in premature infants. However, a majority of these studies have not yielded definitive results because of limited sample size and lack of validation. Despite these challenges, understanding the contribution of genetic variation to NEC is important for providing new insights into the pathogenesis of NEC as well as allowing for targeted care of infants with inherent susceptibility. In this review we provide a summary of published genetic association studies in NEC along with defining the challenges and possible future approaches.

Radiation-induced changes in intestinal and tissue-nonspecific alkaline phosphatase: implications for recovery after radiation therapy

BACKGROUND

Exogenous replacement of depleted enterocyte intestinal alkaline phosphatase (IAP) decreases intestinal injury in models of colitis. We determined whether radiation-induced intestinal injury could be mitigated by oral IAP supplementation and the impact on tissue-nonspecific AP.

METHODS

WAG/RjjCmcr rats (n = 5 per group) received lower hemibody irradiation (13 Gy) followed by daily gavage with phosphate-buffered saline or IAP (40 U/kg/d) for 4 days. Real-time polymerase chain reaction, AP activity, and microbiota analysis were performed on intestine. Lipopolysaccharide and cytokine analysis was performed on serum. Data were expressed as a mean ± SEM with P greater than .05 considered significant.

RESULTS

Intestine of irradiated animals demonstrates lower hemibody irradiation and is associated with upregulation of tissue-nonspecific AP, downregulation of IAP, decreased AP activity, and altered composition of the intestinal microbiome.

CONCLUSIONS

Supplemental IAP after radiation may be beneficial in mitigating intestinal radiation syndrome as evidenced by improved histologic injury, decreased acute intestinal inflammation, and normalization of intestinal microbiome.

mRNA expression of TLR4, TLR9 and NF-κB in a neonatal murine model of necrotizing enterocolitis

A neonatal model of necrotizing enterocolitis (NEC) in mice was established to examine the role of Toll-like receptors (TLRs) 4 and 9, and of nuclear factor (NF)-κB by quantitative detection of their mRNAs in intestinal tissue during the occurrence of NEC, and thus aid in the understanding of the basic pathogenesis of NEC. A total of 50 newborn BALB/c mice (specific pathogen-free level) ranging in age from 7 to 10 days, of either gender, and weighing 4.8–5.4 g were selected and randomly divided into a control and test group, n=25 mice per group. Mice in the control group were kept in the same cage with the mother who fed them, free from any interventions. Mice in the test group were separated from their mother 48 h following birth and placed in an incubator, artificially fed with milk substitutes, and regularly treated with hypoxia and cold stimulation (100% nitrogen anoxia for 90 sec, cold stimulation at 4°C for 10 min, 3 times a day for 3 days) to induce the neonatal NEC. The general state and body weight variations of the mice were recorded, the mice were sacrificed and the intestinal tissue necrosis was evaluated visually, the degree of intestinal injury was determined by histopathological staining, and the mRNA expression levels of intestinal tissue TLR4, TLR9 and NF-κB were quantified. Of the 25 mice in the test group, 3 died a natural death and 22 were sacrificed; their general state was worse than that of the mice in the control group, and the body weight variations among them were considerably larger. NEC was confirmed in 12 cases by visual inspection, and the average histological scores of the mice in the test group were 3.5±0.6, significantly higher than that in the control group (P<0.05). The mRNA expression of TLR4 and NF-κB in the test group were significantly higher than in the control group. By contrast, the mRNA expression of TLR9 was significantly lower in the test group, and differences were statistically significant (P<0.05). Thus, the increased mRNA expression of TLR4 and NF-κB, and decreased mRNA expression of TLR9 during NEC may be an important inflammatory mechanism of the disease.

The immunological landscape in necrotising enterocolitis

Necrotising enterocolitis (NEC) is an uncommon, but devastating intestinal inflammatory disease that predominantly affects preterm infants. NEC is sometimes dubbed the spectre of neonatal intensive care units, as its onset is insidiously non-specific, and once the disease manifests, the damage inflicted on the baby's intestine is already disastrous. Subsequent sepsis and multi-organ failure entail a mortality of up to 65%. Development of effective treatments for NEC has stagnated, largely because of our lack of understanding of NEC pathogenesis. It is clear, however, that NEC is driven by a profoundly dysregulated immune system. NEC is associated with local increases in pro-inflammatory mediators, e.g. Toll-like receptor (TLR) 4, nuclear factor-κB, tumour necrosis factor, platelet-activating factor (PAF), interleukin (IL)-18, interferon-gamma, IL-6, IL-8 and IL-1β. Deficiencies in counter-regulatory mechanisms, including IL-1 receptor antagonist (IL-1Ra), TLR9, PAF-acetylhydrolase, transforming growth factor beta (TGF-β)_1&2, IL-10 and regulatory T cells likely facilitate a pro-inflammatory milieu in the NEC-afflicted intestine. There is insufficient evidence to conclude a predominance of an adaptive Th1-, Th2- or Th17-response in the disease. Our understanding of the accompanying regulation of systemic immunity remains poor; however, IL-1Ra, IL-6, IL-8 and TGF-β₁ show promise as biomarkers. Here, we chart the emerging immunological landscape that underpins NEC by reviewing the involvement and potential clinical implications of innate and adaptive immune mediators and their regulation in NEC.

Long-chain polyunsaturated fatty acids attenuate the IL-1β-induced proinflammatory response in human fetal intestinal epithelial cells

BACKGROUND

Evidence suggests that excessive inflammation of the immature intestine may predispose premature infants to necrotizing enterocolitis (NEC). We investigated the anti-inflammatory effects of docosahexaenoic acid (DHA), eicosapentaenoic acid (EPA), and arachidonic acid (ARA) in human fetal and adult intestinal epithelial cells (IEC) in primary culture.

METHODS

Human fetal IEC in culture were derived from a healthy fetal small intestine (H4) or resected small intestine of a neonate with NEC (NEC-IEC). Intestinal cell lines Caco2 and NCM460 in culture were used as models for mature IEC. IEC in culture were pretreated with 100 µmol/l palmitic acid (PAL), DHA, EPA, ARA, or ARA+DHA for 48 h and then stimulated with proinflammatory IL-1β.

RESULTS

DHA significantly attenuated IL-1β induced proinflammatory IL-8 and IL-6 protein and mRNA in fetal H4, NEC-IEC, and mature Caco2, NCM460 IEC, compared to control and PAL treatment. DHA downregulated IL-1R1 (IL-1β receptor) and NFk β1 mRNA expression in fetal and adult IEC. ARA had potent anti-inflammatory effects with lower IL-8 and IL-6 (protein and mRNA) in fetal H4 but not in NEC-IEC or adult IEC.

CONCLUSION

The present study provides evidence that DHA and ARA may have important anti-inflammatory functions for prevention of NEC in premature infants.

Preterm Birth Reduces Nutrient Absorption With Limited Effect on Immune Gene Expression and Gut Colonization in Pigs

OBJECTIVES

The primary risk factors for necrotizing enterocolitis (NEC) are preterm birth, enteral feeding, and gut colonization. It is unclear whether feeding and colonization induce excessive expression of immune genes that lead to NEC. Using a pig model, we hypothesized that reduced gestational age would upregulate immune-related genes and cause bacterial imbalance after birth.

METHODS

Preterm (85%-92% gestation, n = 53) and near-term (95%-99% gestation, n = 69) pigs were delivered by cesarean section and euthanized at birth or after 2 days of infant formula or bovine colostrum feeding.

RESULTS

At birth, preterm delivery reduced 5 of 30 intestinal genes related to nutrient absorption and innate immunity, relative to near-term pigs, whereas 2 genes were upregulated. Preterm birth also reduced ex vivo intestinal glucose and leucine uptake (40%-50%), but failed to increase cytokine secretions from intestinal explants relative to near-term birth. After 2 days of formula feeding, NEC incidence was increased in preterm versus near-term pigs (47% vs 0%-13%). A total of 6 of the 30 genes related to immunity (TLR2, IL1B, and IL8), permeability (CLDN3, and OCLN), and absorption (SGLT) decreased in preterm pigs without affecting Gram-negative bacteria-related responses (TLR4, IKBA, NFkB1, TNFAIP3, and PAFA). Bacterial abundance tended to be higher in preterm versus near-term pigs (P = 0.09), whereas the composition was unaffected.

CONCLUSIONS

Preterm birth predisposes to NEC and reduces nutrient absorption but does not induce upregulation of immune-related genes or cause bacterial dyscolonization in the neonatal period. Excessive inflammation and bacterial overgrowth may occur relatively late in NEC progression in preterm neonates.

Gene expression profile of necrotizing enterocolitis model in neonatal mice

BACKGROUND

Necrotizing enterocolitis (NEC) characterized by intestinal necrosis is one of the most common gastrointestinal emergencies in newborns. The main purpose of this study was to evaluate the whole genome expression levels in a NEC mouse model controlled with breast milk.

METHODS

This study induced a NEC model in mice of gestational ages of 18-21 days by intensive hypoxic insult and permitted breast-feeding instead of formula feeding. After evaluating the NEC status in the small intestines of neonatal mice by histological examination, a genome-wide gene expression profile study was completed using microarray analysis.

RESULTS

A total of 72 genes (38 down-regulated and 34 up-regulated) were observed to have significantly different expression profiles in the NEC mouse model compared with the normal control animals, based on a significance at fold change ≥ 2 and P < 0.05. In particular, down-regulated Hist1h2aa and up-regulated Ube2i showed the most significant signals (P = 0.0008 for both genes). In an additional gene ontology analysis, the endopeptidase related categories (specifically, serine-type endopeptidase inhibitor activity, P = 8.95 × 10(-5); Pcorr = 0.008) appeared to affect NEC development in the mouse model.

CONCLUSION

Although replications and functional evaluations are needed, our results suggest that several genes may have different expression profiles in the NEC mouse model. In particular, endopeptidase related genes (which are also known to be relevant to NEC), as identified through gene ontology analysis, may represent attractive targets for future research.

Early gradual feeding with bovine colostrum improves gut function and NEC resistance relative to infant formula in preterm pigs

It is unclear when and how to start enteral feeding for preterm infants when mother's milk is not available. We hypothesized that early and slow advancement with either formula or bovine colostrum stimulates gut maturation and prevents necrotizing enterocolitis (NEC) in preterm pigs, used as models for preterm infants. Pigs were given either total parenteral nutrition (TPN, n = 14) or slowly advancing volumes (16-64 ml·kg(-1)·day(-1)) of preterm infant formula (IF, n = 15) or bovine colostrum (BC, n = 13), both given as adjunct to parenteral nutrition. On day 5, both enteral diets increased intestinal mass (27 ± 1 vs. 22 ± 1 g/kg) and glucagon-like peptide 2 release, relative to TPN (P < 0.05). The incidence of mild NEC lesions was higher in IF than BC and TPN pigs (60 vs. 0 and 15%, respectively, P < 0.05). Only the IF pigs showed reduced gastric emptying and gastric inhibitory polypeptide release, and increased tissue proinflammatory cytokine levels (IL-1β and IL-8, P < 0.05) and expression of immune-related genes (AOAH, LBP, CXCL10, TLR2), relative to TPN. The IF pigs also showed reduced intestinal villus-to-crypt ratio, lactose digestion, and some plasma amino acids (Arg, Cit, Gln, Tyr, Val), and higher intestinal permeability, compared with BC pigs (all P < 0.05). Colonic microbiota analyses showed limited differences among groups. Early feeding with formula induces intestinal dysfunction whereas bovine colostrum supports gut maturation when mother's milk is absent during the first week after preterm birth. A diet-dependent feeding guideline may be required for newborn preterm infants.

Quantitative proteomic analysis reveals heat stress-induced injury in rat small intestine via activation of the MAPK and NF-κB signaling pathways

We employed comparative proteomics to reveal a heat stress-induced injury mechanism in rat small intestine.

Animal models of gastrointestinal and liver diseases. Animal models of necrotizing enterocolitis: pathophysiology, translational relevance, and challenges

Necrotizing enterocolitis is the leading cause of morbidity and mortality from gastrointestinal disease in premature infants and is characterized by initial feeding intolerance and abdominal distention followed by the rapid progression to coagulation necrosis of the intestine and death in many cases. Although the risk factors for NEC development remain well accepted, namely premature birth and formula feeding, the underlying mechanisms remain incompletely understood. Current thinking indicates that NEC develops in response to an abnormal interaction between the mucosal immune system of the premature host and an abnormal indigenous microflora, leading to an exaggerated mucosal inflammatory response and impaired mesenteric perfusion. In seeking to understand the molecular and cellular events leading to NEC, various animal models have been developed. However, the large number and variability between the available animal models and the unique characteristics of each has raised important questions regarding the validity of particular models for NEC research. In an attempt to provide some guidance to the growing community of NEC researchers, we now seek to review the key features of the major NEC models that have been developed in mammalian and nonmammalian species and to assess the advantages, disadvantage, challenges and major scientific discoveries yielded by each. A strategy for model validation is proposed, the principal models are compared, and future directions and challenges within the field of NEC research are explored.

A phase I clinical trial of systemically delivered NEMO binding domain peptide in dogs with spontaneous activated B-cell like diffuse large B-cell lymphoma

Activated B-Cell (ABC) Diffuse Large B-Cell Lymphoma (DLBCL) is a common, aggressive and poorly chemoresponsive subtype of DLBCL, characterized by constitutive canonical NF-κB signaling. Inhibition of NF-κB signaling leads to apoptosis of ABC-DLBCL cell lines, suggesting targeted disruption of this pathway may have therapeutic relevance. The selective IKK inhibitor, NEMO Binding Domain (NBD) peptide effectively blocks constitutive NF-κB activity and induces apoptosis in ABC-DLBCL cells in vitro. Here we used a comparative approach to determine the safety and efficacy of systemic NBD peptide to inhibit constitutive NF-κB signaling in privately owned dogs with spontaneous newly diagnosed or relapsed ABC-like DLBCL. Malignant lymph nodes biopsies were taken before and twenty-four hours after peptide administration to determine biological effects. Intravenous administration of <2 mg/kg NBD peptide was safe and inhibited constitutive canonical NF-κB activity in 6/10 dogs. Reductions in mitotic index and Cyclin D expression also occurred in a subset of dogs 24 hours post peptide and in 3 dogs marked, therapeutically beneficial histopathological changes were identified. Mild, grade 1 toxicities were noted in 3 dogs at the time of peptide administration and one dog developed transient subclinical hepatopathy. Long term toxicities were not identified. Pharmacokinetic data suggested rapid uptake of peptide into tissues. No significant hematological or biochemical toxicities were identified. Overall the results from this phase I study indicate that systemic administration of NBD peptide is safe and effectively blocks constitutive NF-κB signaling and reduces malignant B cell proliferation in a subset of dogs with ABC-like DLBCL. These results have potential translational relevance for human ABC-DLBCL.

Recombinant human trefoil factor 3 ameliorates bowel injury: its anti-inflammatory effect on experimental necrotizing enterocolitis

Aim. Recombinant human trefoil factor 3 (intestinal trefoil factor) has been suggested to be partially protective against necrotizing enterocolitis (NEC), but the mechanisms of this protection have not been defined. We investigated whether the protective effects of rhTFF3 are the result of an anti-inflammatory response. Methods. The rats were killed on day 4, the distal ileum was harvested for morphological studies and immunohistochemistry for NF-κB (p65), and the amounts of IL-1β, IL-6, and IL-10 in the intestinal tissue were measured using commercial ELISA assay kits. Results. In the neonatal NEC, IL-1β, IL-6, and IL-10 were significantly higher than in normal group. In normal group, IL-1β and IL-6 were significantly decreased, and the amount of IL-10 was markedly increased compared with NEC group. In the NEC model, immunohistochemical staining for NF-κB (p65) was demonstrated to be of a strong brown color and was distributed in the intestinal epithelium. Treatment with rhTFF3 significantly decreased the immunoreactivity of NF-κB (p65) in the NEC model. Conclusions. Intestinal inflammation was ameliorated after rhTFF3 was injected. rhTFF3 may protect against the intestinal injury of the neonatal rat NEC model by suppression of the inflammatory response.

Amniotic fluid stem cells improve survival and enhance repair of damaged intestine in necrotising enterocolitis via a COX-2 dependent mechanism

OBJECTIVE

Necrotising enterocolitis (NEC) remains one of the primary causes of morbidity and mortality in neonates and alternative strategies are needed. Stem cells have become a therapeutic option for other intestinal diseases, which share some features with NEC. We tested the hypothesis that amniotic fluid stem (AFS) cells exerted a beneficial effect in a neonatal rat model of NEC.

DESIGN

Rats intraperitoneally injected with AFS cells and their controls (bone marrow mesenchymal stem cells, myoblast) were analysed for survival, behaviour, bowel imaging (MRI scan), histology, bowel absorption and motility, immunofluorescence for AFS cell detection, degree of gut inflammation (myeloperoxidase and malondialdehyde), and enterocyte apoptosis and proliferation.

RESULTS

AFS cells integrated in the bowel wall and improved rat survival and clinical conditions, decreased NEC incidence and macroscopic gut damage, improved intestinal function, decreased bowel inflammation, increased enterocyte proliferation and reduced apoptosis. The beneficial effect was achieved via modulation of stromal cells expressing cyclooxygenase 2 in the lamina propria, as shown by survival studies using selective and non-selective cyclooxygenase 2 inhibitors. Interestingly, AFS cells differentially expressed genes of the Wnt/β-catenin pathway, which regulate intestinal epithelial stem cell function and cell migration and growth factors known to maintain gut epithelial integrity and reduce mucosal injury.

CONCLUSIONS

We demonstrated here for the first time that AFS cells injected in an established model of NEC improve survival, clinical status, gut structure and function. Understanding the mechanism of this effect may help us to develop new cellular or pharmacological therapies for infants with NEC.

Beneficial effects of Etanercept on experimental necrotizing enterocolitis

PURPOSE

Tissue damage in necrotizing enterocolitis (NEC) of infants occurs as a result of an uncontrolled inflammatory response. The aim of this study was to investigate any potential anti-inflammatory effects that Etanercept may have on the inflammatory response in an experimental NEC model in newborn rats.

METHODS

Newborn pups were randomized into three groups immediately after birth (Control, NEC + Placebo and NEC + Etanercept). Pups in the NEC + Placebo and NEC + Etanercept groups were subjected to an NEC-inducing protocol (hypercarbia, hypothermia and hyperoxia) twice a day for 3 days. Pups in the NEC + Etanercept group were given an intraperitoneal injection of Etanercept. Rats were harvested for biochemical and histopathological examinations.

RESULTS

The histopathological injury score of rats in the NEC + Placebo group was significantly higher compared to the NEC + Etanercept and Control groups (p < 0.05 for both comparisons). Tissue levels of tumor necrosis factor-α, interleukin-1β, and malondialdehyde were higher in the placebo group compared to the Etanercept group.

CONCLUSION

Our results suggest that Etanercept attenuates intestinal tissue damage in NEC by reducing inflammation and blocking the production of free-oxygen radicals, while also reducing tissue levels of tumor necrosis factor-α and interleukin-1β.

Oral administration of transforming growth factor-β1 (TGF-β1) protects the immature gut from injury via Smad protein-dependent suppression of epithelial nuclear factor κB (NF-κB) signaling and proinflammatory cytokine production

Inflammatory immune responses play an important role in mucosal homeostasis and gut diseases. Nuclear factor κB (NF-κB), central to the proinflammatory cascade, is activated in necrotizing enterocolitis (NEC), a devastating condition of intestinal injury with extensive inflammation in premature infants. TGF-β is a strong immune suppressor and a factor in breast milk, which has been shown to be protective against NEC. In an NEC animal model, oral administration of the isoform TGF-β1 activated the downstream effector Smad2 in intestine and significantly reduced NEC incidence. In addition, TGF-β1 suppressed NF-κB activation, maintained levels of the NF-κB inhibitor IκBα in the intestinal epithelium, and systemically decreased serum levels of IL-6 and IFN-γ. The immature human fetal intestinal epithelial cell line H4 was used as a reductionistic model of the immature enterocyte to investigate mechanism. TGF-β1 pretreatment inhibited the TNF-α-induced IκBα phosphorylation that targets the IκBα protein for degradation and inhibited NF-κB activation. Chromatin immunoprecipitation (ChIP) assays demonstrated decreased NF-κB binding to the promoters of IL-6, IL-8, and IκBα in response to TNF-α with TGF-β1 pretreatment. These TGF-β1 effects appear to be mediated through the canonical Smad pathway as silencing of the TGF-β central mediator Smad4 resulted in loss of the TGF-β1 effects. Thus, TGF-β1 is capable of eliciting anti-inflammatory effects by inhibiting NF-κB specifically in the intestinal epithelium as well as by decreasing systemic IL-6 and IFN-γ levels. Oral administration of TGF-β1 therefore can potentially be used to protect against gastrointestinal diseases.

Helicobacter hepaticus increases intestinal injury in a rat model of necrotizing enterocolitis

Enterohepatic helicobacter species (EHS) infect the intestinal tract and biliary tree, triggering intestinal and hepatic disorders. Helicobacter hepaticus, the prototypic murine EHS, is also associated with inflammation. Necrotizing enterocolitis (NEC) is a devastating disease of premature infants. The cause of NEC is not fully understood, but anomalies of bacterial colonization (dysbiosis) are thought to play an important role in disease onset. To evaluate the effect of H. hepaticus infection on the development of NEC, premature formula-fed rats were kept either in H. hepaticus-free conditions or colonized with H. hepaticus; both groups were exposed to asphyxia and cold stress. The incidence of NEC, expression of Toll-like receptors (TLRs), production of cytokines and mucins, and presence of autophagy regulators were evaluated at the site of injury. H. hepaticus infection increased the incidence of NEC from 39 to 71% and significantly increased levels of TLR4 receptor, expression of proinflammatory cytokines CXCL1, IL-1β, IL-12, and IL-23, and altered activation of autophagy. H. hepaticus induces inflammation and increases the incidence and severity of experimental NEC; this is consistent with observations in neonates of blooms of proinflammatory microbes just before the onset of NEC. Future studies using rodent NEC models should include testing for H. hepaticus infection. Further studies in neonates of early identification and/or diminution of proinflammatory microbes may be beneficial in decreasing the incidence of NEC.

Prematurity and congenital heart disease

Significant advances in technology and therapy have led to dramatic improvements in the survival of preterm babies over the last 2 decades. Similarly, improvements in surgical and cardiac intensive care techniques have increased the feasibility of supporting even very small babies to the point of surgical repair, leading some to adopt an approach of early and complete surgical repair in preterm infants, with the aim of minimizing potential preoperative morbidity associated with extended medical management or surgical palliation. (1,2) However, multiple diagnostic and therapeutic challenges complicate the care of premature infants. Major errors in echocardiography are more common in neonates weighing less than 2.5 kg, (3) and the ideal timing and type of surgical intervention in premature infants remains unknown. These problems are compounded by the need for critical care practices that optimize management of immature cardiopulmonary, gastrointestinal, and neurological systems. This review will summarize some of the recent advances in neonatal and perinatal medicine, which have the potential to contribute to improved management of preterm infants with critical cardiac disease.

Synergistic protection of combined probiotic conditioned media against neonatal necrotizing enterocolitis-like intestinal injury

Balance among the complex interactions of the gut microbial community is important for intestinal health. Probiotic bacteria can improve bacterial balance and have been used to treat gastrointestinal diseases. Neonatal necrotizing enterocolitis (NEC) is a life-threatening inflammatory bowel disorder primarily affecting premature infants. NEC is associated with extensive inflammatory NF-κB signaling activation as well as intestinal barrier disruption. Clinical studies have shown that probiotic administration may protect against NEC, however there are safety concerns associated with the ingestion of large bacterial loads in preterm infants. Bacteria-free conditioned media (CM) from certain probiotic organisms have been shown to retain bioactivity including anti-inflammatory and cytoprotective properties without the risks of live organisms. We hypothesized that the CM from Lactobacillus acidophilus (La), Bifidobacterium infantis (Bi), and Lactobacillus plantarum (Lp), used separately or together would protect against NEC. A rodent model with intestinal injury similar to NEC was used to study the effect of CM from Lp, La/Bi, and La/Bi/Lp on the pathophysiology of NEC. All the CM suppressed NF-κB activation via preserved IκBα expression and this protected IκBα was associated with decreased liver activity of the proteasome, which is the degrading machinery for IκBα. These CM effects also caused decreases in intestinal production of the pro-inflammatory cytokine TNF-α, a downstream target of the NF-κB pathway. Combined La/Bi and La/Bi/Lp CM in addition protected intestinal barrier function by maintaining tight junction protein ZO-1 levels and localization at the tight junction. Double combined La/Bi CM significantly reduced intestinal injury incidence from 43% to 28% and triple combined La/Bi/Lp CM further reduced intestinal injury incidence to 20%. Thus, this study demonstrates different protective mechanisms and synergistic bioactivity of the CM from different organisms in ameliorating NEC-like intestinal injury in an animal model.

Similar efficacy of human banked milk and bovine colostrum to decrease incidence of necrotizing enterocolitis in preterm piglets

Preterm birth and formula feeding predispose to necrotizing enterocolitis (NEC) in infants. As mother's milk is often absent following preterm delivery, infant formula (IF) and human donor milk (HM) are frequently used as alternatives. We have previously shown that porcine and bovine colostrum (BC) provide similar NEC protection in preterm piglets relative to IF. We hypothesized that HM exerts similar effects and that this effect is partly species-independent. Preterm piglets (n = 40) received 2 days of total parenteral nutrition, followed by a rapid transition to full enteral feeding (15 ml·kg(-1)·2 h(-1)) for 2 days using BC (n = 13), HM (n = 13), or IF (n = 14). Intestinal passage time and hexose absorption were tested in vivo. Body and organ weights were recorded on day 5, and macroscopic NEC lesions in the gastrointestinal tract were assessed. Intestinal samples were collected for determination of histomorphology, histopathology, tissue IL-6 and IL-8, organic acids, bacterial adherence by fluorescence in situ hybridization score, and digestive enzyme activities. Relative to IF, pigs from BC and HM showed longer intestinal passage time; higher weight gain, hexose absorptive capacity, mucosal proportion, and enzyme activities; lower NEC incidence, organic acid concentration, and IL-8 concentration; and reduced histopathology lesions. Tissue IL-6 concentration and bacterial adherence score were lower for HM, relative to both BC and IF groups. We conclude that BC and HM are both superior to IF in stimulating gut structure, function, and NEC resistance in preterm piglets. BC may be a relevant alternative to HM when mother's milk is unavailable during the first week after preterm birth.