Association of Intestinal Alkaline Phosphatase With Necrotizing Enterocolitis Among Premature Infants

[Application of near-infrared spectroscopy in the early identification of neonatal gastrointestinal diseases]

Necrotizing enterocolitis (NEC) is one of the most common gastrointestinal diseases in neonatal intensive care units, characterized by rapid progression and a high mortality rate. Local intestinal ischemia and hypoxia are significant contributors to NEC. Feeding intolerance (FI), which refers to a range of gastrointestinal manifestations arising from the inability to tolerate enteral nutrition, is one of the most common clinical issues in neonates, and preventing and treating FI is crucial for improving neonatal survival rates. Near-infrared spectroscopy is a clinical tool that can be used at the bedside to monitor regional oxygen saturation. It is non-invasive, reliable, and sustainable, and its feasibility and safety in assessing intestinal blood circulation have been validated. Early identification of intestinal ischemia and differentiation of FI from precursor symptoms of NEC, as well as predicting the occurrence of NEC, are extremely important for reducing intestinal injury and adverse long-term outcomes. In recent years, there has been new research progress related to the monitoring of intestinal tissue oxygen saturation and cerebral oxygen saturation for the early identification of FI and precursor symptoms of NEC, and this article provides a review of these developments.

Necrotizing enterocolitis: a potential protective role for intestinal alkaline phosphatase as lipopolysaccharide detoxifying enzyme

Introduction

Necrotizing enterocolitis (NEC) is a life-threatening inflammatory disease. Its onset might be triggered by Toll-Like Receptor 4 (TLR4) activation via bacterial lipopolysaccharide (LPS). We hypothesize that a deficiency of intestinal alkaline phosphatase (IAP), an enzyme secreted by enterocytes that dephosphorylates LPS, may contribute to NEC development.

Methods

In this prospective pilot study, we analyzed intestinal resection specimens from surgical NEC patients, and from patients undergoing Roux-Y reconstruction for hepatobiliary disease as controls. We assessed IAP activity via enzymatic stainings and assays and explored IAP and TLR4 co-localization through immunofluorescence.

Results

The study population consisted of five NEC patients (two Bell's stage IIb and three-stage IIIb, median (IQR) gestational age 25 (24-28) weeks, postmenstrual age at diagnosis 28 (26-31) weeks) and 11 controls (unknown age). There was significantly lower IAP staining in NEC resection specimens [49 (41-50) U/g of protein] compared to controls [115 (76-144), P = 0.03]. LPS-dephosphorylating activity was also lower in NEC patients [0.06 (0-0.1)] than in controls [0.3 (0.2-0.5), P = 0.003]. Furthermore, we observed colocalization of IAP and TLR4 in NEC resection specimens.

Conclusion

This study suggests a significantly lower IAP level in resection specimens of NEC patients compared to controls. This lower IAP activity suggests a potential role of IAP as a protective agent in the gut, which needs further confirmation in larger cohorts.

Necrotizing enterocolitis: current understanding of the prevention and management

Necrotizing enterocolitis (NEC) is one of the diseases in neonates, with a high morbidity and mortality rate, especially in preterm infants. This review aimed to briefly introduce the latest epidemiology, susceptibility factors, and clinical diagnosis and presentation of NEC. We also organized new prevention strategies by risk factors according to different pathogeneses and then discussed new treatment methods based on Bell's staging and complications, and the classification of mild to high severity based on clinical and imaging manifestations. Such a generalization will help clinicians and researchers to gain a deeper understanding of the disease and to conduct more targeted classification, grading prevention, and exploration. We focused on prevention and treatment of the early and suspected stages of NEC, including the discovery of novel biomarkers and drugs to control disease progression. At the same time, we discussed its clinical application, future development, and shortcomings.

Protective Properties of Intestinal Alkaline Phosphatase Supplementation on the Intestinal Barrier: Interactions and Effects

The intestinal barrier is critical for maintaining intestinal homeostasis, and its dysfunction is associated with various diseases. Recent findings have revealed the multifunctional role of intestinal alkaline phosphatase (IAP) in diverse biological processes, including gut health maintenance and function. This review summarizes the protective effects of IAP on intestinal barrier integrity, encompassing the physical, chemical, microbial, and immune barriers. We discuss the results and insights from in vitro, animal model, and clinical studies as well as the available evidence regarding the impact of diet on IAP activity and expression. IAP can also be used as an indicator to assess intestinal-barrier-related diseases. Further research into the mechanisms of action and long-term health effects of IAP in maintaining overall intestinal health is essential for its future use as a dietary supplement or functional component in medical foods.

Alteration of stool pH and its association with biomarkers of gut enteropathy among slum-dwelling women of reproductive age in Bangladesh

BACKGROUND

Recent evidence suggests that measures of maternal gut enteropathy are associated with unfavorable fetal outcomes. It is, therefore, crucial to identify and treat the features of intestinal enteropathy among reproductive-age women living in areas where enteropathy is highly prevalent. However, there is a lack of non-invasive diagnostic tests to determine EED, making it difficult to identify the disease in field settings. In this study, we tested the potential of fecal pH as a biomarker of gut enteropathy and investigated its relationship with fecal biomarkers of intestinal enteropathy in reproductive-age women living in resource-limited environments.

METHODS

Data on socio-demographic information, anthropometry, and biological samples were collected from 78 apparently healthy women aged between 20 and 27 years from November 2018 to December 2019. The association of stool pH with two fecal biomarkers of gut enteropathy (i.e., intestinal alkaline phosphatase [IAP] and fecal lipocalin-2 [LCN-2] was investigated using multiple linear regression models after adjusting for relevant covariates.

RESULTS

In the adjusted models, alkaline stool pH (pH > 7.2) was found to be significantly associated with a decrease in the fecal IAP level by 1.05 unit (95% CI: -1.68, -0.42; p < 0.001) in the log scale, and acidic stool pH (pH < 6) was found to be significantly associated with an increase in the fecal LCN-2 level by 0.89 units (95% CI: 0.12, 1.67; p < 0.025) in the log scale.

CONCLUSIONS

The study findings demonstrated an association of fecal pH with biomarkers of gut enteropathy indicating its applicability as a simple tool for understanding intestinal enteropathy among reproductive-age women living in resource-limited settings.

Association of anemia and platelet activation with necrotizing enterocolitis with or without sepsis among low birth weight neonates: a case-control study

Background

This study aims to evaluate the value of the proportion of large platelets (PLCR) and platelet crit (PCT) in predicting necrotizing enterocolitis (NEC) in low birth weight (LBW) neonates.

Methods

A total of 155 LBW (<2,500 g) neonates with NEC, who were admitted to the neonatal intensive care unit (NICU) of the hospital from January 1, 2017, to November 30, 2019, were included in the case group. According to the 1:3 case-control study design, a total of 465 LBW neonates without NEC (three for each LBW neonate with NEC), who were admitted to the NICU and born ≤24 h before or after the birth of the subjects, were included in the control group.

Results

During the study period, a total of 6,946 LBW neonates were born, of which 155 had NEC, including 92 who also had sepsis. Neonatal sepsis was the most important risk factor and confounding factor for NEC in LBW neonates. Further stratified analysis showed that in LBW neonates without sepsis, anemia [P = 0.001, odds ratio (OR) = 4.367, 95% confidence interval (CI): 1.853-10.291], high PLCR (P < 0.001, OR = 2.222, 95% CI: 1.633-3.023), and high PCT (P = 0.024, OR = 1.368, 95% CI: 1.042-1.795) increased the risk of NEC and the receiver operating characteristic curve area of PLCR, sensitivity, specificity, and cutoff value were 0.739, 0.770, 0.610, and 33.55, respectively.

Conclusions

The results showed that 2/100 LBW neonates were at risk for NEC, and the stratified analysis of the confounding factors of sepsis identified the risk factors of NEC in LBW neonates. This study first reported the significance of PLCR in the early prediction of NEC occurrence in LBW neonates without sepsis.

The role of intestinal alkaline phosphatase in the development of necrotizing enterocolitis

Necrotizing enterocolitis (NEC) is a devastating neonatal disease that affects neonates worldwide and often leads to high morbidity and mortality rates. Despite extensive research, the cause of NEC remains unclear, and current treatment options are limited. An important novel finding is the potential role of intestinal Alkaline Phosphatase (IAP) in both pathogenesis and treatment of NEC. IAP can play a vital role in detoxifying liposaccharides (LPS), a key mediator of many pathological processes, thereby reducing the inflammatory response associated with NEC. Furthermore, IAP can help prevent dysbiosis, improve intestinal perfusion, and promote autophagy. In this comprehensive review, we present evidence of the possible connection between IAP and the LPS/Toll-like receptor 4 (TLR4) pathway, impaired gut immunity, and dysbiosis in the preterm gut. Based on these findings, the administration of exogenous IAP might provide promising preventive and therapeutic avenues for the management of NEC.

Necrotizing enterocolitis in premature infants-A defect in the brakes? Evidence from clinical and animal studies

A key aspect of postnatal intestinal adaptation is the establishment of symbiotic relationships with co-evolved gut microbiota. Necrotizing enterocolitis (NEC) is the most severe disease arising from failure in postnatal gut adaptation in premature infants. Although pathological activation of intestinal Toll-like receptors (TLRs) is believed to underpin NEC pathogenesis, the mechanisms are incompletely understood. We postulate that unregulated aberrant TLR activation in NEC arises from a failure in intestinal-specific mechanisms that tamponade TLR signaling (the brakes). In this review, we discussed the human and animal studies that elucidate the developmental mechanisms inhibiting TLR signaling in the postnatal intestine (establishing the brakes). We then evaluate evidence from preclinical models and human studies that point to a defect in the inhibition of TLR signaling underlying NEC. Finally, we provided a framework for the assessment of NEC risk by screening for signatures of TLR signaling and for NEC prevention by TLR-targeted therapy in premature infants.

Proteomics Profiling of Stool Samples from Preterm Neonates with SWATH/DIA Mass Spectrometry for Predicting Necrotizing Enterocolitis

Necrotizing enterocolitis (NEC) is a life-threatening condition for premature infants in neonatal intensive care units. Finding indicators that can predict NEC development before symptoms appear would provide more time to apply targeted interventions. In this study, stools from 132 very-low-birth-weight (VLBW) infants were collected daily in the context of a multi-center prospective study aimed at investigating the potential of fecal biomarkers for NEC prediction using proteomics technology. Eight of the VLBW infants received a stage-3 NEC diagnosis. Stools collected from the NEC infants up to 10 days before their diagnosis were available for seven of them. Their samples were matched with those from seven pairs of non-NEC controls. The samples were processed for liquid chromatography-tandem mass spectrometry analysis using SWATH/DIA acquisition and cross-compatible proteomic software to perform label-free quantification. ROC curve and principal component analyses were used to explore discriminating information and to evaluate candidate protein markers. A series of 36 proteins showed the most efficient capacity with a signature that predicted all seven NEC infants at least a week in advance. Overall, our study demonstrates that multiplexed proteomic signature detection constitutes a promising approach for the early detection of NEC development in premature infants.

Emerging prediction methods for early diagnosis of necrotizing enterocolitis

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

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.

Intestinal Alkaline Phosphatase: A Review of This Enzyme Role in the Intestinal Barrier Function

Intestinal alkaline phosphatase (IALP) has recently assumed a special relevance, being the subject of study in the prevention and treatment of certain diseases related to leaky gut. This brush border enzyme (ecto-enzyme) plays an important role in the maintenance of intestinal microbial homeostasis and intestinal barrier function through its ability to dephosphorylate lipopolysaccharide (LPS). This review addresses how IALP and intestinal barrier dysfunction may be implicated in the pathophysiology of specific diseases such as inflammatory bowel disease, necrotizing enterocolitis, and metabolic syndrome. The use of IALP as a possible biomarker to assess intestinal barrier function and strategies to modulate IALP activity are also discussed.

Lipocalin-2 and calprotectin as stool biomarkers for predicting necrotizing enterocolitis in premature neonates

BACKGROUND

Necrotizing enterocolitis (NEC) is a major challenge for premature infants in neonatal intensive care units and efforts toward the search for indicators that could be used to predict the development of the disease have given limited results until now.

METHODS

In this study, stools from 132 very low birth weight infants were collected daily in the context of a multi-center prospective study aimed at investigating the potential of fecal biomarkers for NEC prediction. Eight infants (~6%) received a stage 3 NEC diagnosis. Their stools collected up to 10 days before diagnosis were included and matched with 14 non-NEC controls and tested by ELISA for the quantitation of eight biomarkers.

RESULTS

Biomarkers were evaluated in all available stool samples leading to the identification of lipocalin-2 and calprotectin as the two most reliable predicting markers over the 10-day period prior to NEC development. Pooling the data for each infant confirmed the significance of lipocalin-2 and calprotectin, individually and in combination 1 week in advance of the NEC clinical diagnosis.

CONCLUSIONS

The lipocalin-2 and calprotectin tandem represents a significant biomarker signature for predicting NEC development. Although not yet fulfilling the "perfect biomarker" criteria, it represents a first step toward it.

IMPACT

Stool biomarkers can be used to predict NEC development in very low birth weight infants more than a week before the diagnosis. LCN2 was identified as a new robust biomarker for predicting NEC development, which used in conjunction with CALPRO, allows the identification of more than half of the cases that will develop NEC in very low birth weight infants. Combining more stool markers with the LCN2/CALPRO tandem such as PGE2 can further improve the algorithm for the prediction of NEC development.

Necrotizing enterocolitis in the preterm: newborns medical and nutritional Management in a Single-Center Study

Necrotizing enterocolitis (NEC) is a typical disorder of preterm newborns, with a high mortality and morbidity rate. The therapeutic and nutritional management of disease depends on several factors. Its prognosis is linked, in addition to the severity of the disease and the need for surgery, to a correct enteral feeding in these patients. This study aims to identify the clinical characteristics of 18 patients with NEC, evaluating the different therapeutic paths undertaken, the type of formula used and the survival rate of this population. Average time of enteral nutrition before the NEC onset was 11,3 ± 11,6 days, with an average fasting period since the onset of 24 ± 18.9 days. 77.8% of patients received surgery and resumed enteral nutrition 17.7 ± 17.9 days after the intervention. The overall survival rate of our cohort was 55.5%. More prospective studies are needed to evaluate the long-term outcomes of survived children with NEC.

Targeting the Intestinal Barrier to Prevent Gut-Derived Inflammation and Disease: A Role for Intestinal Alkaline Phosphatase

Background

Intestinal alkaline phosphatase (IAP) as a tissue-specific isozyme of alkaline phosphatases is predominantly produced by enterocytes in the proximal small intestine. In recent years, an increasing number of pathologies have been identified to be associated with an IAP deficiency, making it very worthwhile to review the various roles, biological functions, and potential therapeutic aspects of IAP.

Summary

IAP primarily originates and acts in the intestinal tract but affects other organs through specific biological axes related to its fundamental roles such as promoting gut barrier function, dephosphorylation/detoxification of lipopolysaccharides (LPS), and regulation of gut microbiota.

Key Messages

Numerous studies reporting on the different roles and the potential therapeutic value of IAP across species have been published during the last decade. While IAP deficiency is linked to varying degrees of physiological dysfunctions across multiple organ systems, the supplementation of IAP has been proven to be beneficial in several translational and clinical studies. The increasing evidence of the salutary functions of IAP underlines the significance of the naturally occurring brush border enzyme.

Influence of Human Milk on Very Preterms' Gut Microbiota and Alkaline Phosphatase Activity

The FEEDMI Study (NCT03663556) evaluated the influence of infant feeding (mother's own milk (MOM), donor human milk (DHM) and formula) on the fecal microbiota composition and alkaline phosphatase (ALP) activity in extremely and very preterm infants (≤32 gestational weeks). In this observational study, preterm infants were recruited within the first 24 h after birth. Meconium and fecal samples were collected at four time points (between the 2nd and the 26th postnatal days. Fecal microbiota was analyzed by RT-PCR and by 16S rRNA sequencing. Fecal ALP activity, a proposed specific biomarker of necrotizing enterocolitis (NEC), was evaluated by spectrophotometry at the 26th postnatal day. A total of 389 fecal samples were analyzed from 117 very preterm neonates. Human milk was positively associated with beneficial bacteria, such as Bifidobacterium, Bacteroides ovatus, and Akkermancia muciniphila, as well as bacterial richness. Neonates fed with human milk during the first week of life had increased Bifidobacterium content and fecal ALP activity on the 26th postnatal day. These findings point out the importance of MOM and DHM in the establishment of fecal microbiota on neonates prematurely delivered. Moreover, these results suggest an ALP pathway by which human milk may protect against NEC.

TFF3 mediates the NF-κB/COX2 pathway to regulate PMN-MDSCs activation and protect against necrotizing enterocolitis

Intestinal trefoil factor 3 (TFF3) plays an important role in repairing the intestinal mucosa. However, the detailed mechanism regarding immune regulation by TFF3 is not well defined. Here, we reported that treatment of mouse BM cells and human peripheral blood mononuclear cells from healthy volunteers with TFF3 activated polymorphnuclear myeloid-derived suppressor cells (PMN-MDSCs) in vitro. We also found that prostaglandin E2 is a major TFF3-mediated MDSC target, and that NF-κB/COX2 signaling was involved in this process. Moreover, TFF3 treatment or transfer of TFF3-derived PMN-MDSCs (TFF3-MDSCs) to experimental necrotizing enterocolitis (NEC) mice caused PMN-MDSC accumulation in the lamina propria (LP), which was associated with decreased intestinal inflammation, permeability, bacterial loading, and prolonged survival. Interestingly, no NEC severity remission was observed in Rag1 KO mice that were given TFF3-MDSCs, but coinjection with CD4⁺ T cells significantly relieved NEC inflammation. Overall, TFF3 mediates the NF-κB/COX2 pathway to regulate PMN-MDSC activation and attenuates NEC in a T-cell-dependent manner, which suggests a novel mechanism in preventing NEC occurrence.

Precision-based modeling approaches for necrotizing enterocolitis

Necrotizing enterocolitis (NEC) is the leading cause of death from gastrointestinal disease in premature infants and remains stubbornly difficult to treat in many cases. Much of our understanding of NEC pathogenesis has been gained through the study of highly translational animal models. However, most models of NEC are limited by their overall complexity and by the fact that they do not incorporate human tissue. To address these limitations, investigators have recently developed precision-based ex vivo models of NEC, also termed ‘NEC-in-a-dish’ models, which provide the opportunity to increase our understanding of this disease and for drug discovery. These approaches involve exposing intestinal cells from either humans or animals with or without NEC to a combination of environmental and microbial factors associated with NEC pathogenesis. This Review highlights the current progress in the field of NEC model development, introduces NEC-in-a-dish models as a means to understand NEC pathogenesis and examines the fundamental questions that remain unanswered in NEC research. By answering these questions, and through a renewed focus on precision model development, the research community may finally achieve enduring success in improving the outcome of patients with this devastating disease.

Summary: Much of our understanding of necrotizing enterocolitis (NEC) pathogenesis has been achieved through animal models. Here, we discuss the development of advanced precision-based models to improve outcomes for patients with NEC.

Nutrition in Necrotizing Enterocolitis and Following Intestinal Resection

This review aims to discuss the role of nutrition and feeding practices in necrotizing enterocolitis (NEC), NEC prevention, and its complications, including surgical treatment. A thorough PubMed search was performed with a focus on meta-analyses and randomized controlled trials when available. There are several variables in nutrition and the feeding of preterm infants with the intention of preventing necrotizing enterocolitis (NEC). Starting feeds later rather than earlier, advancing feeds slowly and continuous feeds have not been shown to prevent NEC and breast milk remains the only effective prevention strategy. The lack of medical treatment options for NEC often leads to disease progression requiring surgical resection. Following resection, intestinal adaptation occurs, during which villi lengthen and crypts deepen to increase the functional capacity of remaining bowel. The effect of macronutrients on intestinal adaptation has been extensively studied in animal models. Clinically, the length and portion of intestine that is resected may lead to patients requiring parenteral nutrition, which is also reviewed here. There remain significant gaps in knowledge surrounding many of the nutritional aspects of NEC and more research is needed to determine optimal feeding approaches to prevent NEC, particularly in infants younger than 28 weeks and <1000 grams. Additional research is also needed to identify biomarkers reflecting intestinal recovery following NEC diagnosis individualize when feedings should be safely resumed for each patient.

Premature Birth Infants Present Elevated Inflammatory Markers in the Meconium

Introduction: Prematurity, a well-established risk factor for various intestinal diseases in newborns, results in increased morbidity and mortality. However, the intestinal inflammatory status of preterm (PT) infants has been poorly characterized. Here we have broadly described the intestinal and systemic inflammatory status of PT children. Materials and Methods: Meconium and plasma from 39 PT and 32 full term (T) newborns were studied. Fecal calprotectin, polymorphonuclear leukocyte elastase (PMN-E), TNF, IL-17A, IL-8, IP-10, MCP-1, MIP-1, IL-1β, IL-1α, and E-selectin and the enzymatic activities of myeloperoxidase (MPO) and alkaline phosphatase (AP) in meconium were measured. Plasma levels of AP, hepatocyte growth factor, nerve growth factor (NGF), proinflammatory cytokines, leptin, adiponectin, PAI-1, and resistin were also determined. Correlations with gestational age (GA) and birth weight (BW) were studied. Results: Neutrophil derived PMN-E, MPO and calprotectin were increased in the meconium of PT compared to T newborns, while AP was decreased. No significant differences were found in other inflammatory parameters. Considering data from all children, GA and BW showed inverse correlation with neutrophil markers, while AP directly correlated with BW. Plasma levels of IL-1β and NGF were enhanced in PT infants, and were also negatively correlated with BW. PT children additionally showed neutropenia and decreased adiponectin, leptin, haematocrit, and haemoglobin. These parameters (neutrophils, adiponectin, and so forth) were positively correlated with GA and BW, while IL-8, MCP-1, PAI-1, and plasma AP were negatively correlated. PT children showing postnatal morbidity exhibited increased meconium MPO and MIP-1α. Conclusion: PT neonates present a significant elevation of intestinal inflammatory parameters, characterized by the presence of neutrophil markers, associated with mild systemic inflammation.

Differences in Serum Alkaline Phosphatase Levels in Infants with Spontaneous Intestinal Perforation versus Necrotizing Enterocolitis with Perforation

INTRODUCTION

Data on laboratory markers of spontaneous intestinal perforation (SIP) and necrotizing enterocolitis (NEC) remain sparse.

OBJECTIVE

To compare serum alkaline phosphatase levels in infants with bowel perforation secondary to SIP versus surgical NEC, and then investigate the possible role of serum alkaline phosphatase in differentiating infants with these conditions.

METHODS

A retrospective case-control study of infants admitted with bowel perforation from 2005 to 2015. Demographic and prenatal data, postnatal exposures, and clinical, laboratory, and radiographic findings were extracted from inpatient medical records and analyzed using regression analysis.

RESULTS

Of 114 outborn infants included, 48 infants had SIP (cases) and 66 had NEC (controls). Upon admission from the referring hospital, the serum alkaline phosphatase level was significantly higher in infants with SIP, i.e., a median value of 782 versus236 U/L in NEC patients (p < 0.0001), with an adjusted odds ratio (OR) of 4.3 (p < 0.05) when the level was >500 U/L in multivariate regression model. Infants with SIP had significantly younger gestational age, presented earlier in life, primarily with pneumoperitoneum, and had greater exposure to steroids and indomethacin compared to infants with NEC. Alkaline phosphatase levels decreased rapidly in infants with SIP following admission.

CONCLUSION

A transient increase in serum alkaline phosphatase level is independently associated with SIP when compared to NEC. Studies to confirm the role of alkaline phosphatase in the diagnosis of SIP are necessary and have potentially significant clinical and prognostic implications.