Myth: necrotizing enterocolitis: probiotics will end the disease, and surgical intervention improves the outcome

Bacteroides fragilis ameliorates Cronobacter malonaticus lipopolysaccharide-induced pathological injury through modulation of the intestinal microbiota

Cronobacter has attracted considerable attention due to its association with meningitis and necrotizing enterocolitis (NEC) in newborns. Generally, lipopolysaccharide (LPS) facilitates bacterial translocation along with inflammatory responses as an endotoxin; however, the pathogenicity of Cronobacter LPS and the strategies to alleviate the toxicity were largely unknown. In this study, inflammatory responses were stimulated by intraperitoneal injection of Cronobacter malonaticus LPS into Sprague–Dawley young rats. Simultaneously, Bacteroides fragilis NCTC9343 were continuously fed through gavage for 5 days before or after injection of C. malonaticus LPS to evaluate the intervention effect of B. fragilis. We first checked the morphological changes of the ileum and colon and the intestinal microbiota and then detected the generation of inflammatory factors, including tumor necrosis factor-alpha (TNF-α), interleukin-1 beta (IL-1β), interleukin-6 (IL-6), and interleukin-10 (IL-10) and the expression of Toll-like receptor 4 (TLR4), occludin, claudin-4, and iNOs. The results indicated that C. malonaticus LPS exacerbated intestinal infection by altering gut microbe profile, tight junction protein expression, and releasing inflammatory factors in a time- and dose-dependent manner. Intriguingly, treatment with B. fragilis obviously diminished the pathological injuries and expression of TLR4 caused by C. malonaticus LPS while increasing gut microbes like Prevotella-9. We note that Shigella, Peptoclostridium, and Sutterella might be positively related to C. malonaticus LPS infection, but Prevotella-9 was negatively correlated. The results suggested that the intestinal microbiota is an important target for the prevention and treatment of pathogenic injuries induced by C. malonaticus LPS.

Effect of a Multi-Strain Probiotic on the Incidence and Severity of Necrotizing Enterocolitis and Feeding Intolerances in Preterm Neonates

Background: Necrotizing enterocolitis (NEC) is a multifactorial disease, causing inflammation of the bowel. The exact root of NEC is still unknown, but a low weight and gestational age at birth are known causes. Furthermore, antibiotic use and abnormal bacterial colonization of the premature gut are possible causes. Premature neonates often experience feeding intolerances that disrupts the nutritional intake, leading to poor growth and neurodevelopmental impairment. Methods: We conducted a double-blind, placebo-controlled, randomized clinical trial to investigate the effect of a multi-strain probiotic formulation (LabinicTM) on the incidence and severity of NEC and feeding intolerances in preterm neonates. Results: There were five neonates in the placebo group who developed NEC (Stage 1A−3B), compared to no neonates in the probiotic group. Further, the use of probiotics showed a statistically significant reduction in the development of feeding intolerances, p < 0.001. Conclusion: A multi-strain probiotic is a safe and cost-effective way of preventing NEC and feeding intolerances in premature neonates.

Intestinal Stem Cell Development in the Neonatal Gut: Pathways Regulating Development and Relevance to Necrotizing Enterocolitis

The intestine is extremely dynamic and the epithelial cells that line the intestine get replaced every 3–5 days by highly proliferative intestinal stem cells (ISCs). The instructions for ISCs to self-renew or to differentiate come as cues from their surrounding microenvironment or their niche. A small number of evolutionarily conserved signaling pathways act as a critical regulator of the stem cells in the adult intestine, and these pathways are well characterized. However, the mechanisms, nutritional, and environmental signals that help establish the stem cell niche in the neonatal intestine are less studied. Deciphering the key signaling pathways that regulate the development and maintenance of the stem cells is particularly important to understanding how the intestine regenerates from necrotizing enterocolitis, a devastating disease in newborn infants characterized by inflammation, tissues necrosis, and stem cell injury. In this review, we piece together current knowledge on morphogenetic and immune pathways that regulate intestinal stem cell in neonates and highlight how the cross talk among these pathways affect tissue regeneration. We further discuss how these key pathways are perturbed in NEC and review the scientific knowledge relating to options for stem cell therapy in NEC gleaned from pre-clinical experimental models of NEC.

Inclusion of Probiotics into Fermented Buffalo (Bubalus bubalis) Milk: An Overview of Challenges and Opportunities

Buffalo-milk-based dairy products provide various health benefits to humans since buffalo milk serves as a rich source of protein, fat, lactose, calcium, iron, phosphorus, vitamin A and natural antioxidants. Dairy products such as Meekiri, Dadih, Dadi and Lassie, which are derived from Artisanal fermentation of buffalo milk, have been consumed for many years. Probiotic potentials of indigenous microflora in fermented buffalo milk have been well documented. Incorporation of certain probiotics into the buffalo-milk-based dairy products conferred vital health benefits to the consumers, although is not a common practice. However, several challenges are associated with incorporating probiotics into buffalo-milk-based dairy products. The viability of probiotic bacteria can be reduced due to processing and environmental stress during storage. Further, incompatibility of probiotics with traditional starter cultures and high acidity of fermented dairy products may lead to poor viability of probiotics. The weak acidifying performance of probiotics may affect the organoleptic quality of fermented dairy products. Besides these challenges, several innovative technologies such as the use of microencapsulated probiotics, ultrasonication, the inclusion of prebiotics, use of appropriate packaging and optimal storage conditions have been reported, promising stability and viability of probiotics in buffalo-milk-based fermented dairy products.

Colonization with Escherichia coli EC 25 protects neonatal rats from necrotizing enterocolitis

Necrotizing enterocolitis (NEC) is a significant cause of morbidity and mortality in premature infants; yet its pathogenesis remains poorly understood. To evaluate the role of intestinal bacteria in protection against NEC, we assessed the ability of naturally occurring intestinal colonizer E. coli EC25 to influence composition of intestinal microbiota and NEC pathology in the neonatal rat model. Experimental NEC was induced in neonatal rats by formula feeding/hypoxia, and graded histologically. Bacterial populations were characterized by plating on blood agar, scoring colony classes, and identifying each class by sequencing 16S rDNA. Binding of bacteria to, and induction of apoptosis in IEC-6 enterocytes were examined by plating on blood agar and fluorescent staining for fragmented DNA. E. coli EC 25, which was originally isolated from healthy rats, efficiently colonized the intestine and protected from NEC following introduction to newborn rats with formula at 10⁶ or 10⁸ cfu. Protection did not depend significantly on EC25 inoculum size or load in the intestine, but positively correlated with the fraction of EC25 in the microbiome. Introduction of EC25 did not prevent colonization with other bacteria and did not significantly alter bacterial diversity. EC25 neither induced cultured enterocyte apoptosis, nor protected from apoptosis induced by an enteropathogenic strain of Cronobacter muytjensii. Our results show that E. coli EC25 is a commensal strain that efficiently colonizes the neonatal intestine and protects from NEC.

Probiotics for the prevention of necrotising enterocolitis in very low-birth-weight infants: a meta-analysis and systematic review

We performed an updated meta-analysis incorporating the results of recent randomised controlled trials (RCTs) to measure the effectiveness of probiotic supplementation in preventing necrotising enterocolitis (NEC) and death in very low-birth-weight (VLBW) infants, and to investigate any differences in efficacy by probiotic agent. Using meta-regression analysis, we assessed the contribution of other measured variables on the overall effect size and between-study variability.

CONCLUSION

Overall, probiotics lead to significant reductions in NEC incidence and mortality in VLBW infants. Differences in probiotic agents and the influence of prenatal steroids and feeding regimens may explain the differences in outcomes between studies.

Probiotics and necrotizing enterocolitis

Probiotics for the prevention of necrotizing enterocolitis have attracted a huge interest. Combined data from heterogeneous randomised controlled trials suggest that probiotics may decrease the incidence of NEC. However, the individual studies use a variety of probiotic products, and the group at greatest risk of NEC, i.e., those with a birth weight of less than 1000 g, is relatively under-represented in these trials so we do not have adequate evidence of either efficacy or safety to recommend universal prophylactic administration of probiotics to premature infants. These problems have polarized neonatologists, with some taking the view that it is unethical not to universally administer probiotics to premature infants, whereas others regard the meta-analyses as flawed and that there is insufficient evidence to recommend routine probiotic administration. Another problem is that the mechanism by which probiotics might act is not clear, although some experimental evidence is starting to accumulate. This may allow development of surrogate endpoints of effectiveness, refinement of probiotic regimes, or even development of pharmacological agents that may act through the same mechanism. Hence, although routine probiotic administration is controversial, studies of probiotic effects may ultimately lead us to effective means to prevent this devastating disease.

Prevention and early recognition of necrotizing enterocolitis: a tale of 2 tools--eNEC and GutCheckNEC

BACKGROUND AND SIGNIFICANCE

Risk for neonatal necrotizing enterocolitis (NEC) is complex, reflecting its multifactorial pathogenesis.

PURPOSE

To improve risk awareness and facilitate communication among neonatal caregivers, especially nurses, 2 tools were developed.

DESIGN

GutCheck was derived and validated as part of a formal research study over 3 phases, evidence synthesis, expert consensus building, and statistical modeling. The Wetzel/Krisman tool, eNEC, was developed and tested as part of a quality improvement initiative in a single clinical setting using evidence synthesis, review by internal expert clinicians, and implementation and evaluation of its use by direct line neonatal staff. Refinement of both tools is under way to evaluate their effect on clinical decision making, early identification of NEC and surgical NEC.

METHODS AND MAIN OUTCOMES

Clinicians can take an active role to reduce NEC in their units by focusing on modifiable risk factors such as adoption of standardized feeding protocols, preferential feeding of human milk, and antibiotic and histamine blocker stewardship.

RESULTS

Feeding during transfusion remains controversial, but judicious use of transfusions, adoption of transfusion guidelines, and withholding feeding during transfusion are feasible measures with potential benefit to prevent NEC and confer little risk.

Toll-like receptor regulation of intestinal development and inflammation in the pathogenesis of necrotizing enterocolitis

Toll-like receptors (TLRs) are a structurally related family of molecules that respond to a wide variety of endogenous and exogenous ligands, and which serve as important components of the innate immune system. While TLRs have established roles in host defense, these molecules have also been shown to play important roles in the development of various disease states. A particularly important example of the role of TLRs in disease induction includes necrotizing enterocolitis (NEC), which is the most common gastrointestinal disease in preterm infants, and which is associated with extremely high morbidity and mortality rates. The development of NEC is thought to reflect an abnormal interaction between microorganisms and the immature intestinal epithelium, and emerging evidence has clearly placed the spotlight on an important and exciting role for TLRs, particularly TLR4, in NEC pathogenesis. In premature infants, TLR4 signaling within the small intestinal epithelium regulates apoptosis, proliferation and migration of enterocytes, affects the differentiation of goblet cells, and reduces microcirculatory perfusion, which in combination result in the development of NEC. This review will explore the signaling properties of TLRs on hematopoietic and non-hematopoietic cells, and will examine the role of TLR4 signaling in the development of NEC. In addition, the effects of dampening TLR4 signaling using synthetic and endogenous TLR4 inhibitors and active components from amniotic fluid and human milk on NEC severity will be reviewed. In so doing, we hope to present a balanced approach to the understanding of the role of TLRs in both immunity and disease pathogenesis, and to dissect the precise roles for TLR4 in both the cause and therapeutic intervention of necrotizing enterocolitis.

Stem cells as a potential therapy for necrotizing enterocolitis

INTRODUCTION

Necrotizing enterocolitis (NEC) is a severe gastrointestinal disease of neonates, especially those born prematurely, that remains an important cause of morbidity and mortality. Although current treatments such as inotropes, antibiotics and ventilation are supportive, there is an urgent need for novel therapies that specifically target the affected intestine.

AREAS COVERED

We briefly introduce the disease and the effects on intestinal epithelia. We provide a brief description of amniotic fluid stem (AFS) cells, and then describe some recent data in which AFS cells were beneficial in an animal model of NEC and a potential mechanism is described. The effects of AFS cells are compared with data on bone marrow mesenchymal stem cells. The potential implications of these findings for therapy are discussed.

EXPERT OPINION

The current data are promising and demonstrate that stem cells do have an effect in rodent models of NEC. However, the short timescale, limited ability for longitudinal evaluation and uncertain clinical relevance of these models means that there are considerable challenges to be overcome before attempting stem cell therapy in clinical trials. Nevertheless, these data open up novel areas of research into a prevention or therapy for this devastating disease.

Bacterial and fungal viability in the preterm gut: NEC and sepsis

BACKGROUND AND AIMS

Evidence suggests that microbial communities in the preterm gut may influence the development of necrotising enterocolitis (NEC) and sepsis. Existing data often neglect fungi and whether bacteria were metabolically active or not. We sought to characterise the bacterial and fungal stool flora of preterm neonates and organism viability and evaluate any associations with NEC and sepsis.

PATIENTS

136 stools from 32 patients (<32 weeks gestation) were collected between birth and day 95. Seven infants developed NEC and 13 sepsis.

METHODS

Stools were analysed by PCR-DGGE for assessment of the total bacterial and fungal communities by analysis of 16S rRNA and 28S rRNA, respectively. In 65 samples (25 infants), the viable (RNA) bacterial and fungal communities were analysed. Analyses were performed to examine the possible effects of demographic or treatment related factors and the development of NEC or sepsis.

RESULTS

80 (66 viable) bacterial species were identified overall and 12 fungal (none viable). Total bacterial communities significantly differed between healthy infants and those with NEC or sepsis, with Sphingomonas spp. significantly associated with NEC. Significant drivers of community structure differed based on either total or viable analysis. Antifungal prophylaxis was associated with altered bacterial community and a reduction in bacterial richness was observed in week 4, correlating with high antibiotic exposure.

CONCLUSIONS

Total and viable communities differ in preterm infants, and non-viable fungal species are present in infants on fungal prophylaxis. Exploration of viability and non-bacterial contributors to the total community may increase understanding of NEC and sepsis.

Lactobacillus reuteri strains reduce incidence and severity of experimental necrotizing enterocolitis via modulation of TLR4 and NF-κB signaling in the intestine

Necrotizing enterocolitis (NEC) is the leading gastrointestinal cause of mortality and morbidity in the premature infant. Premature infants have a delay in intestinal colonization by commensal bacteria and colonization with potentially pathogenic organisms. Lactobacillus reuteri is a probiotic that inhibits enteric infections, modulates the immune system, and may be beneficial to prevent NEC. In previous studies, L. reuteri strains DSM 17938 and ATCC PTA 4659 differentially modulated inflammation in vitro; however, the strains had equivalent anti-inflammatory responses in LPS feeding-induced ileitis in neonatal rats in vivo. The impact of these two strains in the prevention of NEC has not been previously investigated. NEC was induced in newborn rats by orogastric formula feeding and exposure to hypoxia. L. reuteri was added to the formula to prevent NEC. NEC score, Toll-like receptor (TLR)-signaling genes, phospho-IκB activity, and cytokine levels in the intestine were examined. Both strains significantly increased survival rate and decreased the incidence and severity of NEC, with optimal effects from DSM 17938. In response to probiotic, mRNA expression of IL-6, TNF-α, TLR4, and NF-κB was significantly downregulated, while mRNA levels of anti-inflammatory cytokine IL-10 were significantly upregulated. In parallel, L. reuteri treatment led to decrease intestinal protein levels of TLR4 and cytokine levels of TNF-α and IL-1β in newborn rats with NEC. Both strains significantly inhibited not only intestinal LPS-induced phospho-IκB activity in an ex vivo study but also decreased the levels of phospho-IκB in the intestines of NEC rat model. Cow milk formula feeding produced a similar but milder proinflammatory profile in the intestine that was also ameliorated by 17938. Our studies demonstrate that each of the two L. reuteri strains has potential therapeutic value in our NEC model and in enteritis associated with cow milk feeding. These results support the concept that L. reuteri may represent a valuable treatment to prevent NEC.