Association of neonatal necrotizing enterocolitis with myeloid differentiation-2 and GM2 activator protein genetic polymorphisms

Recent advances in our understanding of NEC diagnosis, prognosis and surgical approach

Necrotising enterocolitis (NEC) remains a devasting condition that has seen limited improvement in outcomes in recent years. The incidence of the disease is increasing as more extremely premature infants survive. NEC is responsible for 1 in 10 neonatal deaths and up to 61% of survivors have significant neurodevelopmental delay. The aim of this review is to highlight recent advances in diagnosis, prognosis and surgical approach in this condition. Many recent studies have reported novel methods of diagnosis of NEC with the aim of earlier and more accurate identification. These include imaging and machine learning techniques. Prognostication of NEC is particularly important to allow earlier escalation of therapy. Around 25% of infants with NEC will require surgery and recent data has shown that time from disease onset to surgery is greater in infants whose indication for surgery is failed medical management, rather than pneumoperitoneum. This indication was also associated with worse outcomes compared to pneumoperitoneum. Ongoing research has highlighted several new methods of disease prognostication which includes differentiating surgical from medical NEC. Finally, recent randomised controlled trials in surgical technique are discussed along with the implications of these for practice. Further, high quality research utilising multi-centre collaborations and high fidelity data from electronic patient records is needed to address the issues discussed and ultimately improve outcomes in NEC.

Role of gut-brain axis in neurodevelopmental impairment of necrotizing enterocolitis

Necrotizing enterocolitis (NEC) is a common gastrointestinal disease of preterm infants with high morbidity and mortality. In survivors of NEC, one of the leading causes of long-term morbidity is the development of severe neurocognitive injury. The exact pathogenesis of neurodevelopmental delay in NEC remains unknown, but microbiota is considered to have dramatic effects on the development and function of the host brain via the gut-brain axis. In this review, we discuss the characteristics of microbiota of NEC, the impaired neurological outcomes, and the role of the complex interplay between the intestinal microbiota and brain to influence neurodevelopment in NEC. The increasing knowledge of microbial-host interactions has the potential to generate novel therapies for manipulating brain development in the future.

Selective targeting of MD2 attenuates intestinal inflammation and prevents neonatal necrotizing enterocolitis by suppressing TLR4 signaling

Neonatal necrotizing enterocolitis (NEC) is an inflammatory disease that occurs in premature infants and has a high mortality rate; however, the mechanisms behind this disease remain unclear. The TLR4 signaling pathway in intestinal epithelial cells, mediated by TLR4, is important for the activation of the inflammatory storm in NEC infants. Myeloid differentiation protein 2 (MD2) is a key auxiliary component of the TLR4 signaling pathway. In this study, MD2 was found to be significantly increased in intestinal tissues of NEC patients at the acute stage. We further confirmed that MD2 was upregulated in NEC rats. MD2 inhibitor (MI) pretreatment reduced the occurrence and severity of NEC in neonatal rats, inhibited the activation of NF-κB and the release of inflammatory molecules (TNF-α and IL-6), and reduced the severity of intestinal injury. MI pretreatment significantly reduced enterocyte apoptosis while also maintaining tight junction proteins, including occludin and claudin-1, and protecting intestinal mucosal permeability in NEC rats. In addition, an NEC in vitro model was established by stimulating IEC-6 enterocytes with LPS. MD2 overexpression in IEC-6 enterocytes significantly activated NF-κB. Further, both MD2 silencing and MI pretreatment inhibited the inflammatory response. Overexpression of MD2 increased damage to the IEC-6 monolayer cell barrier, while both MD2 silencing and MI pretreatment played a protective role. In conclusion, MD2 triggers an inflammatory response through the TLR4 signaling pathway, leading to intestinal mucosal injury in NEC. In addition, MI alleviates inflammation and reduces intestinal mucosal injury caused by the inflammatory response by blocking the TLR4-MD2/NF-κB signaling axis. These results suggest that inhibiting MD2 may be an important way to prevent 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.

Biomarkers of gut injury in neonates - where are we in predicting necrotising enterocolitis?

Despite advances in neonatal care Necrotising Enterocolitis (NEC) continues to have a significant mortality and morbidity rate, and with increasing survival of those more immature infants the population at risk of NEC is increasing. Ischaemia, reperfusion, and inflammation underpin diseases affecting intestinal blood flow causing gut injury including Necrotising Enterocolitis. There is increasing interest in tissue biomarkers of gut injury in neonates, particularly those representing changes in intestinal wall barrier and permeability, to determine whether these could be useful biomarkers of gut injury. This article reviews current and newly proposed markers of gut injury, the available literature evidence, recent advances and considers how effective they are in clinical practice. We discuss each biomarker in terms of its effectiveness in predicting NEC onset and diagnosis or predicting NEC severity and then those that will aid in surveillance and identifying those infants are greatest risk of developing NEC.

Potential Prenatal Origins of Necrotizing Enterocolitis

Necrotizing enterocolitis is a serious and yet incompletely understood gastrointestinal disease of infancy that predominately impacts premature neonates. Prevention is a key strategy for the management of necrotizing enterocolitis. Although postnatal risk factors have been the focus of prevention efforts, obstetric complications, including intrauterine inflammation and infection, growth restriction, preeclampsia, and prenatal medications, have been associated with an increased risk of necrotizing enterocolitis. This article reviews the evidence behind the prenatal risk factors for necrotizing enterocolitis, and discusses how these risk factors may elucidate the pathogenesis of necrotizing enterocolitis and provide insight into prevention and treatment.

Association of High-Mobility Group Box 1 (HMGB1) Gene Polymorphisms with Susceptibility and Better Survival Prognosis in Chinese Han Neonatal Necrotizing Enterocolitis

BACKGROUND High-mobility group box 1 (HMGB1) plays a crucial role in a variety of diseases, including neonatal necrotizing enterocolitis (NEC). The purpose of this study was to investigate the association of HMGB1 gene single-nucleotide polymorphisms (SNPs) with susceptibility and survival prognosis in Chinese Han neonates with NEC. MATERIAL AND METHODS The HMGB1 gene rs1360485, rs1045411, and rs2249825 site SNPs were genotyped in all participants. The mRNA expression of serum HMGB1 was examined using quantitative reverse transcription-polymerase chain reaction. The correlation of the HMGB1 rs1360485 SNP with NEC neonatal survival prognosis was evaluated by univariate analysis and logistic multivariate regression analysis. RESULTS The TC and CC genotype and C allele distribution frequencies of the rs1360485 SNP were lower in the NEC group, and the differences were statistically significant (all P<0.05). Individuals carrying the TC and CC genotype or C allele had a low risk of being affected by NEC. However, the genotype and allele distributions of rs1045411 and rs2249825 were not significantly different between the patient and control groups (P>0.05). NEC neonates with HMGB1 gene rs1360485 site mutations had lower mRNA levels of serum HMGB1 than those with rs1360485 site wild-type, and the rs1360485 genotypes TC and CC could independently predict better survival outcomes in NEC neonates. CONCLUSIONS This study demonstrated that the rs1360485 SNP of the HMGB1 gene is associated with susceptibility of NEC in neonates, and the rs1360485 genotypes TC and CC may affect HMGB1 expression and are associated with the survival prognosis of neonates with NEC.

Recent Potential Noninvasive Biomarkers in Necrotizing Enterocolitis

Necrotizing enterocolitis (NEC) is a rare but devastating gastrointestinal disease that predominately affects preterm neonates. Numerous studies have revealed that NEC is strongly associated with very low birth weight, degree of prematurity, formula feeding, infection, hypoxic/ischemic injury, and enteric dysbiosis. Given these clinical associations, the search for a deeper understanding of disease pathogenesis has led to an intense interest in the discovery and development of noninvasive biomarkers of NEC from stool, urine, and serum. Biomarkers for NEC may serve at least two general purposes of urgent unmet need: to improve diagnostic accuracy and disease prediction and to reveal the mechanism of the disease. This review will provide an overview of recent research focused on clinical NEC and highlight the advances that were made within the past five years towards the development of noninvasive diagnostic biomarkers.

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.

Biomarkers of necrotizing enterocolitis: a review of literature

Necrotizing enterocolitis (NEC) is among the most serious gastrointestinal emergency in very low birth weight (VLBW), extremely low birth weight (ELBW) and extremely low gestational age neonates (ELGAN), affecting 7-14% of these neonates. Despite extensive research, the underlying aetiology of NEC still remains blurred. Due to high mortality, morbidity and its delayed presentation, early detection of NEC is considered to be lifesaving. A number of biomarkers have been studied for early detection and prediction of severity of NEC but till date, no ideal marker has been discovered. Molecular techniques like proteomic and metabolomic have recently emerged in the field for the development of biomarkers for early detection and understanding the pathophysiology of NEC. We did literature search for identifying all biomarkers that have been used for the detection of NEC and, in this review article, we discuss these biomarkers along with the available current evidence.

Association of single nucleotide polymorphisms of IL23R and IL17 with necrotizing enterocolitis in premature infants

Necrotizing enterocolitis (NEC) is a severe gastrointestinal inflammatory disease in neonates, particularly in preterm infants. The interleukin (IL) 23/IL17 axis has been shown to play an important role in the gastrointestinal inflammation. However, the association of gene polymorphisms in the IL23/IL17 axis and the development of NEC remains unknown. In this study, we aimed to explore a possible genetic role of IL23R and IL17 in the development of NEC. We identified single nucleotide polymorphisms (SNPs) in IL23R (rs10889677), IL17A (rs2275913), and IL17F (rs763780) by polymerase chain reaction and Sanger sequencing. A total of 102 NEC patients (stage II, n = 75; and stage III, n = 27) and 120 control subjects were recruited for the study. All of the participants were premature (gestational age < 37 weeks). Our results revealed that the combination of the IL17F rs763780 (TC + CC) genotype and the C allele both significantly increased the risk of NEC [odds ratio (OR) 1.89, 95% confidence interval (CI) 1.04-3.43, P = 0.035; OR 1.82, 95% CI 1.06-3.13, P = 0.028, respectively]. Furthermore, the rs763780 (TC + CC) genotype was associated with increased severity of NEC and the incidence of NEC-related perforation [OR 2.80, 95% CI 1.10-7.12, P = 0.031; OR 3.86, 95% CI 1.10-13.53, P = 0.035, respectively]. However, IL23R rs10889677 and IL17A rs2275913 were not associated with the susceptibility to NEC. In conclusion, our data suggest that a variant of IL17F (rs763780) may contribute to the development of NEC.

Pathogenesis of NEC: Impact of an altered intestinal microbiome

Necrotizing enterocolitis (NEC), a disease most commonly seen in preterm infants, often presents without warning and is associated with very high mortality and morbidity. Progress in the prevention and treatment of NEC has been slow. In this article, we will discuss some of the reasons as to why this progress has been slow. We will describe some of the factors that appear to be highly associated and important components in the pathophysiology of NEC. We will discuss the intestinal microbial environment of the fetus as well as the preterm infant and how interaction of dysbiosis with an immature gastrointestinal tract combined with dietary factors play a role in the pathogenesis of NEC. Testable hypotheses are discussed as well as how these may lead to not only a better understanding of the pathophysiology of the disease but also the preventative strategies.

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.

Genetic variations of NOD2 and MD2 genes in hepatitis B virus infection

OBJECTIVES

Nucleotide oligomerization domain 2 (NOD2) and myeloid differentiation protein 2 (MD-2) have crucial roles in the innate immune system. NOD2 is a member of the NOD-like receptor (NLR) family of pattern recognition receptors (PRRs), while MD-2 is a co-receptor for Toll-like receptor 4 (TLR4), which comprises another group of PRRs. Genetic variations in the NOD2 and MD-2 genes may be susceptibility factors to viral pathogens including hepatitis B virus (HBV). We investigated whether polymorphisms at NOD2 (rs2066845 and rs2066844) or at MD-2 (rs6472812 and rs11466004) were associated with susceptibility to HBV infection and advancement to related liver complications in a Saudi Arabian population. Methods: A total of 786 HBV-infected patients and 600 healthy uninfected controls were analyzed in the present study. HBV-infected patients were categorized into three groups based on the clinical stage of the infection: inactive HBV carriers, active HBV carriers, and patients with liver cirrhosis + hepatocellular carcinoma (HCC). Results: All four SNPs were significantly associated with susceptibility to HBV infection although none of the SNPs tested in NOD2 and MD-2 were significantly associated with persistence of HBV infection. We found that HBV-infected patients that were homozygous CC for rs2066845 in the NOD2 gene were at a significantly increased risk of progression to HBV-related liver complications (Odds Ratio = 7.443 and P = 0.044). Furthermore, haplotype analysis found that the rs2066844-rs2066845 C-G and T-G haplotypes at the NOD2 gene and four rs6472812-rs11466004 haplotypes (G-C, G-T, A-C, and A-T) at the MD-2 gene were significantly associated with HBV infection in the affected cohort compared to those found in our control group. Conclusion: We found that the single nucleotide polymorphisms rs2066844 and rs2066845 at NOD2 and rs6472812 and rs11466004 at MD-2 were associated with susceptibility to HBV infection in a Saudi population.

Association between the p.Thr1406Asn polymorphism of the carbamoyl-phosphate synthetase 1 gene and necrotizing enterocolitis: A prospective multicenter study

The p.Thr1406Asn (rs1047891) polymorphism of the carbamoyl-phosphate synthetase 1 (CPS1) gene has been linked to functional consequences affecting the downstream availability of the nitric oxide precursor L-arginine. L-arginine concentrations are decreased in preterm infants with necrotizing enterocolitis (NEC). In this multicenter prospective study, we investigated the association of the p.Thr1406Asn polymorphism with NEC in 477 preterm infants (36 cases of NEC) from 4 European neonatal intensive care units (Maastricht, Las Palmas de Gran Canaria, Mantova, and Milan). Allele and genotype frequencies of the p.Thr1406Asn polymorphism did not significantly differ between the infants with and without NEC. In contrast, the minor A-allele was significantly less frequent in the group of 64 infants with the combined outcome NEC or death before 34 weeks of corrected gestational age than in the infants without the outcome (0.20 vs. 0.31, P = 0.03). In addition, a significant negative association of the A-allele with the combined outcome NEC or death was found using the dominant (adjusted odds ratio, aOR: 0.54, 95% CI 0.29–0.99) and the additive (aOR 0.58, 95% CI 0.36–0.93) genetic models. In conclusion, our study provides further evidence that a functional variant of the CPS1 gene may contribute to NEC susceptibility.

Necrotizing enterocolitis: new insights into pathogenesis and mechanisms

Necrotizing enterocolitis (NEC) is the most frequent and lethal disease of the gastrointestinal tract of preterm infants. At present, NEC is thought to develop in the premature host in the setting of bacterial colonization, often after administration of non-breast milk feeds, and disease onset is thought to be due in part to a baseline increased reactivity of the premature intestinal mucosa to microbial ligands as compared with the full-term intestinal mucosa. The increased reactivity leads to mucosal destruction and impaired mesenteric perfusion and partly reflects an increased expression of the bacterial receptor Toll-like receptor 4 (TLR4) in the premature gut, as well as other factors that predispose the intestine to a hyper-reactive state in response to colonizing microorganisms. The increased expression of TLR4 in the premature gut reflects a surprising role for this molecule in the regulation of normal intestinal development through its effects on the Notch signalling pathway. This Review will examine the current approach to the diagnosis and treatment of NEC, provide an overview of our current knowledge regarding its molecular underpinnings and highlight advances made within the past decade towards the development of specific preventive and treatment strategies for this devastating disease.