Probiotics and necrotizing enterocolitis

Neonatal Necrotizing Enterocolitis: An Update on Pathophysiology, Treatment, and Prevention

Necrotizing enterocolitis (NEC) is a life-threatening disease predominantly affecting premature and very low birth weight infants resulting in inflammation and necrosis of the small bowel and colon and potentially leading to sepsis, peritonitis, perforation, and death. Numerous research efforts have been made to better understand, treat, and prevent NEC. This review explores a variety of factors involved in the pathogenesis of NEC (prematurity, low birth weight, lack of human breast milk exposure, alterations to the microbiota, maternal and environmental factors, and intestinal ischemia) and reports treatment modalities surrounding NEC, including pain medications and common antibiotic combinations, the rationale for these combinations, and recent antibiotic stewardship approaches surrounding NEC treatment. This review also highlights the effect of early antibiotic exposure, infections, proton pump inhibitors (PPIs), and H2 receptor antagonists on the microbiota and how these risk factors can increase the chances of NEC. Finally, modern prevention strategies including the use of human breast milk and standardized feeding regimens are discussed, as well as promising new preventative and treatment options for NEC including probiotics and stem cell therapy.

Probiotic formulations and gastro-intestinal diseases in the paediatric population: a narrative review

Background/Aim

Probiotics are live microbial supplements that improve the microbial balance in the host animal when administered in adequate amounts. They play an important role in relieving symptoms of many diseases associated with gastrointestinal tract, for example, in necrotizing enterocolitis (NEC), antibiotic-associated diarrhea, relapsing Clostridium difficile colitis, Helicobacter pylori infections, and inflammatory bowel disease (IBD). In this narrative review, the authors aim to evaluate the role of different probiotic formulations in treating gastrointestinal diseases in pediatric population aged 18 years or younger and highlight the main considerations for selecting probiotic formulations for use in this population.

Methodology

The authors searched PubMed and Clinicaltrials.gov from inception to 24th July 2022, without any restrictions. Using an iterative process, the authors subsequently added papers through hand-searching citations contained within retrieved articles and relevant systematic reviews and meta-analyses.

Results

The effectiveness of single-organism and composite probiotics in treating gastrointestinal disorders in pediatric patients aged 18 or under were analyzed and compared in this study. A total of 39 studies were reviewed and categorized based on positive and negative outcomes, and compared with a placebo, resulting in 25 studies for single-organism and 14 studies for composite probiotics. Gastrointestinal disorders studied included NEC, acute gastroenteritis (AGE), Acute Diarrhea, Ulcerative Colitis (UC), and others. The results show that probiotics are effective in treating various gastrointestinal disorders in children under 18, with single-organism probiotics demonstrating significant positive outcomes in most studies, and composite probiotics showing positive outcomes in all studies analyzed, with a low incidence of negative outcomes for both types.

Conclusion

This study concludes that single-organism and composite probiotics are effective complementary therapies for treating gastrointestinal disorders in the pediatric population. Hence, healthcare professionals should consider using probiotics in standard treatment regimens, and educating guardians can enhance the benefits of probiotic therapy. Further research is recommended to identify the optimal strains and dosages for specific conditions and demographics. The integration of probiotics in clinical practice and ongoing research can contribute to reducing the incidence and severity of gastrointestinal disorders in pediatric patients.

Factors influencing necrotizing enterocolitis in premature infants in China: a systematic review and meta-analysis

BACKGROUND

Necrotizing enterocolitis (NEC) is a multifactorial gastrointestinal disease with high morbidity and mortality among premature infants. However, studies with large samples on the factors of NEC in China have not been reported. This meta-analysis aims to systematically review the literature to explore the influencing factors of necrotizing enterocolitis in premature infants in China and provide a reference for the prevention of NEC.

METHODS

PubMed, Embase, Web of Science, Cochrane Library, China National Knowledge Infrastructure (CNKI), China Biomedical Literature Database (CBM), Wanfang and VIP databases were systematically searched from inception to February 2023. We used Stata14.0 software to perform the systematic review and meta-analysis. We used fixed or random effects models with combined odds ratios (ORs) and 95% confidence intervals (CIs), and quality was evaluated using the Newcastle‒Ottawa Scale (NOS).

RESULTS

The total sample was 8616 cases, including 2456 cases in the intervention group and 6160 cases in the control group. It was found that 16 risk factors and 3 protective factors were related to necrotizing enterocolitis in premature infants. Septicemia (OR = 3.91), blood transfusion (OR = 2.41), neonatal asphyxia (OR = 2.46), pneumonia (OR = 6.17), infection (OR = 5.99), congenital heart disease (OR = 4.80), intrahepatic cholestasis of pregnancy (ICP) (OR = 2.71), mechanical ventilation (OR = 1.44), gestational diabetes mellitus (GDM) (OR = 3.08), respiratory distress syndrome (RDS) (OR = 3.28), hypoalbuminemia (OR = 2.80), patent ductus arteriosus (PDA) (OR = 3.10), respiratory failure (OR = 7.51), severe anemia (OR = 2.86), history of antibiotic use (OR = 2.12), and meconium-stained amniotic fluid (MSAF) (OR = 3.14) were risk factors for NEC in preterm infants in China. Breastfeeding (OR = 0.31), oral probiotics (OR = 0.36), and prenatal use of glucocorticoids (OR = 0.38) were protective factors for NEC in preterm infants.

CONCLUSIONS

Septicemia, blood transfusion, neonatal asphyxia, pneumonia, infection, congenital heart disease, ICP, GDM, RDS, hypoproteinemia, PDA, respiratory failure, severe anemia, history of antibiotic use and MSAF will increase the risk of NEC in premature infants, whereas breastfeeding, oral probiotics and prenatal use of glucocorticoids reduce the risk. Due to the quantity and quality of the included literature, the above findings need to be further validated by more high-quality studies.

Role of innate T cells in necrotizing enterocolitis

Necrotizing enterocolitis (NEC) is a destructive gastrointestinal disease primarily affecting preterm babies. Despite advancements in neonatal care, NEC remains a significant cause of morbidity and mortality in neonatal intensive care units worldwide and the etiology of NEC is still unclear. Risk factors for NEC include prematurity, very low birth weight, feeding with formula, intestinal dysbiosis and bacterial infection. A review of the literature would suggest that supplementation of prebiotics and probiotics prevents NEC by altering the immune responses. Innate T cells, a highly conserved subpopulation of T cells that responds quickly to stimulation, develops differently from conventional T cells in neonates. This review aims to provide a succinct overview of innate T cells in neonates, encompassing their phenotypic characteristics, functional roles, likely involvement in the pathogenesis of NEC, and potential therapeutic implications.

Necrotizing Enterocolitis Complicating Severe RSV Bronchiolitis in PICU Settings

This retrospective study aims to analyze the baseline characteristics and factors associated with poor outcomes in patients with necrotizing enterocolitis (NEC) complicating respiratory syncytial virus (RSV) infection. Using the Virtual Pediatric Systems data registry, patients under 2 years admitted to the pediatric intensive care unit (PICU) were screened. Patients with documented RSV infection and NEC, intestinal perforation, noninfectious gastroenteritis/colitis, or pneumatosis intestinalis occurring around the timing of RSV bronchiolitis diagnosis were included. Out of the screened patients, 41 were analyzed. Most patients (93%) were aged 30 days to 2 years, one-third had baseline anatomical cardiac defects, and 20% history of prematurity. Median PICU length of stay was 11.7 days. Seven patients died before hospital discharge. While not statistically significant, nonsurvivors tended to exhibit higher PRISM-3 scores, more acidemia, and lower systolic blood pressure. These findings emphasize the need for cautious assessment of gastrointestinal symptoms in critically ill patients with RSV infection.

Probiotics for the postoperative management of term neonates after gastrointestinal surgery

BACKGROUND

The intestinal microflora has an essential role in providing a barrier against colonisation of pathogens, facilitating important metabolic functions, stimulating the development of the immune system, and maintaining intestinal motility. Probiotics are live microorganisms that can be administered to supplement the gut flora. Neonates who have undergone gastrointestinal surgery are particularly susceptible to infectious complications in the postoperative period. This may be partly due to a disruption of the integrity of the gut and its intestinal microflora. There may be a role for probiotics in reducing the incidence of sepsis and improving intestinal motility, thus reducing morbidity and mortality and improving enteral feeding in neonates in the postoperative period.

OBJECTIVES

To evaluate the efficacy and safety of administering probiotics after gastrointestinal surgery for the postoperative management of neonates born from 35 weeks of gestation.

SEARCH METHODS

We searched CENTRAL, MEDLINE, Embase, and trial registries in August 2023. We checked reference lists of included studies and relevant systematic reviews for additional studies.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) that investigated the postoperative administration of oral probiotics versus placebo or no treatment in neonates born from 35 weeks of gestation who had one or more gastrointestinal surgical procedures. We applied no restrictions regarding the type or dosage of probiotics or the duration of treatment.

DATA COLLECTION AND ANALYSIS

We used standard Cochrane methods, and we used GRADE to assess the certainty of evidence.

MAIN RESULTS

We identified one RCT that recruited 61 neonates with a gestational age of 35 weeks or more. All infants were admitted to a neonatal intensive care unit and had surgery for gastrointestinal pathologies. There may be little or no difference in proven sepsis (positive bacterial culture, local or systemic) between infants who receive probiotics compared with those who receive placebo (odds ratio (OR) 0.64, 95% confidence interval (CI) 0.16 to 2.55; 61 infants; low-certainty evidence). Probiotics compared to placebo may have little or no effect on time to full enteral feeds (mean difference (MD) 0.63 days, 95% CI -4.02 to 5.28; 61 infants; low-certainty evidence). There were no reported deaths prior to discharge from hospital in either study arm. Two weeks after supplementation, the infants who received probiotics had a substantially higher relative abundance of non-pathogenic intestinal microflora (Bifidobacteriaceae) than those who received placebo (MD 38.22, 95% CI 28.40 to 48.04; 39 infants; low-certainty evidence).

AUTHORS' CONCLUSIONS

This review provides low-certainty evidence from one small RCT that probiotics compared to placebo have little or no effect on the risk of proven sepsis (positive bacterial culture, local or systemic) or time to full-enteral feeds in neonates who have undergone gastrointestinal surgery. Probiotics may substantially increase the abundance of beneficial bacterial in the intestine of these neonates, but the clinical implications of this finding are unknown. There is a need for adequately powered RCTs to assess the role of probiotics in this population. We identified two ongoing studies. As neither reported the gestational age of prospective study participants, we are unsure if they will be eligible for inclusion in this review.

Microbiome dysbiosis: a modifiable state and target to prevent Staphylococcus aureus infections and other diseases in neonates

Bacterial infections present a significant threat to neonates. Increasingly, studies demonstrate associations between human diseases and the microbiota, the communities of microorganisms on or in the body. A "healthy" microbiota with a great diversity and balance of microorganisms can resist harmful pathogens and protect against infections, whereas a microbiota suffering from dysbiosis, can predispose to pathogen colonization and subsequent infection. For decades, strategies such as bacterial interference, decolonization, prebiotics, and probiotics have been tested to reduce Staphylococcus aureus disease and other infections in neonates. More recently, microbiota transplant has emerged as a strategy to broadly correct dysbiosis, promote colonization resistance, and prevent infections. This paper discusses the benefits of a healthy neonate's microbiota, exposures that alter the microbiota, associations of dysbiosis and neonatal disease, strategies to prevent dysbiosis, such as microbiota transplantation, and presents a framework of microbiome manipulation to reduce Staphylococcus aureus (S. aureus) and other infections in neonates.

Prevalence and risk factors associated with the need for surgical intervention due to necrotizing enterocolitis in very low birth weight infants

INTRODUCTION

Necrotizing enterocolitis (NEC) is one of the most common gastrointestinal emergencies affecting very low birth weight (VLBW) infants with an incidence of 6-15 %. Early recognition is crucial. Mortality is high and variable (30-50 %). Those requiring surgical intervention have a higher mortality rate than those who receive medical treatment.

OBJECTIVES

1) To assess the prevalence of surgical NEC and associated risk factors 2) To compare outcomes based on the type of treatment required 3) To estimate the mortality associated with NEC and surgical NEC.

METHODS

A multicentre retrospective cohort study was designed (level II), including VLBW infants born between 2011 and 2020 in Centers of the Neocosur Network. A multivariate logistic regression analysis was performed to evaluate risk factors associated with the need for surgery.

RESULTS

NEC was diagnosed in 1679 (10.4 %) of 16,131 births in this period. The prevalence of surgery was 25 % (95 % CI 23-27 %). In multivariable analysis, variables associated with an increased risk of surgery requirement were birth weight <750 g (aOR 1.73-95%CI 1.2-2.5) and receiving antenatal antibiotics (aOR 1.54-95%CI 1.09-2.74). Those requiring surgery had significantly higher morbidity and mortality than the ones receiving medical treatment.

CONCLUSION

In VLBW infants with NEC, lower birth weight and antenatal antibiotics administration were independently associated with the need for surgical intervention.

Clinical Dilemma Involving Treatments for Very Low-Birth-Weight Infants and the Potential Risk of Necrotizing Enterocolitis: A Narrative Literature Review

Necrotizing enterocolitis (NEC) is a critical gastrointestinal emergency with substantial morbidity and mortality risks, especially for very low-birth-weight (VLBW) infants, and unclear multifactorial pathophysiology. Whether common treatments for VLBW infants increase the NEC risk remains controversial. Indomethacin (utilized for patent ductus arteriosus) offers benefits but is concerning because of its vasoconstrictive impact on NEC susceptibility. Similarly, corticosteroids used to treat bronchopulmonary dysplasia may increase vulnerability to NEC by compromising immunity and altering the mesenteric blood flow. Histamine-2 receptor blockers (used to treat gastric bleeding) may inadvertently promote NEC by affecting bacterial colonization and translocation. Doxapram (used to treat apnea) poses a risk of gastrointestinal disturbance via gastric acid hypersecretion and circulatory changes. Glycerin enemas aid meconium evacuation but disrupt microbial equilibrium and trigger stress-related effects associated with the NEC risk. Prolonged antibiotic use may unintentionally increase the NEC risk. Blood transfusions for anemia can promote NEC via interactions between the immune response and ischemia-reperfusion injury. Probiotics for NEC prevention are associated with concerns regarding sepsis and bacteremia. Amid conflicting evidence, this review unveils NEC risk factors related to treatments for VLBW infants, offers a comprehensive overview of the current research, and guides personalized management strategies, thereby elucidating this clinical dilemma.

Factors Influencing Neonatal Gut Microbiome and Health with a Focus on Necrotizing Enterocolitis

Maturational changes in the gut start in utero and rapidly progress after birth, with some functions becoming fully developed several months or years post birth including the acquisition of a full gut microbiome, which is made up of trillions of bacteria of thousands of species. Many factors influence the normal development of the neonatal and infantile microbiome, resulting in dysbiosis, which is associated with various interventions used for neonatal morbidities and survival. Extremely low gestational age neonates (<28 weeks' gestation) frequently experience recurring arterial oxygen desaturations, or apneas, during the first few weeks of life. Apnea, or the cessation of breathing lasting 15-20 s or more, occurs due to immature respiratory control and is commonly associated with intermittent hypoxia (IH). Chronic IH induces oxygen radical diseases of the neonate, including necrotizing enterocolitis (NEC), the most common and devastating gastrointestinal disease in preterm infants. NEC is associated with an immature intestinal structure and function and involves dysbiosis of the gut microbiome, inflammation, and necrosis of the intestinal mucosal layer. This review describes the factors that influence the neonatal gut microbiome and dysbiosis, which predispose preterm infants to NEC. Current and future management and therapies, including the avoidance of dysbiosis, the use of a human milk diet, probiotics, prebiotics, synbiotics, restricted antibiotics, and fecal transplantation, for the prevention of NEC and the promotion of a healthy gut microbiome are also reviewed. Interventions directed at boosting endogenous and/or exogenous antioxidant supplementation may not only help with prevention, but may also lessen the severity or shorten the course of the disease.

Utilization of a High Potency Probiotic Product for Prevention of Necrotizing Enterocolitis in Preterm Infants at a Level IV NICU

Necrotizing enterocolitis (NEC) is a serious gastrointestinal disease that can be seen in premature infants with high risk for morbidity and mortality. There is currently no US Food and Drug Administration (FDA) medication approved for the prevention of NEC. Despite great heterogeneity among available studies, large meta-analyses of clinical trials have demonstrated the efficacy of multiple-strain probiotics in reducing NEC and all-cause mortality. In 2020, Medical City Dallas's Level IV neonatal intensive care unit (NICU) implemented a probiotic protocol for NEC prevention. As a result, a reduction in NEC was observed, with no occurrence of probiotic-related sepsis.

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.

Probiotics to prevent necrotising enterocolitis in very preterm or very low birth weight infants

BACKGROUND

Intestinal dysbiosis may contribute to the pathogenesis of necrotising enterocolitis (NEC) in very preterm or very low birth weight (VLBW) infants. Dietary supplementation with probiotics to modulate the intestinal microbiome has been proposed as a strategy to reduce the risk of NEC and associated mortality and morbidity in very preterm or VLBW infants.

OBJECTIVES

To determine the effect of supplemental probiotics on the risk of NEC and associated mortality and morbidity in very preterm or very low birth weight infants.

SEARCH METHODS

We searched CENTRAL, MEDLINE, Embase, the Maternity and Infant Care database, and CINAHL from inception to July 2022. We searched clinical trials databases and conference proceedings, and examined the reference lists of retrieved articles.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) and quasi-RCTs comparing probiotics with placebo or no probiotics in very preterm infants (born before 32 weeks' gestation) and VLBW infants (weighing less than 1500 g at birth).

DATA COLLECTION AND ANALYSIS

Two review authors independently evaluated risk of bias of the trials, extracted data, and synthesised effect estimates using risk ratios (RRs), risk differences (RDs), and mean differences (MDs), with associated 95% confidence intervals (CIs). The primary outcomes were NEC and all-cause mortality; secondary outcome measures were late-onset invasive infection (more than 48 hours after birth), duration of hospitalisation from birth, and neurodevelopmental impairment. We used the GRADE approach to assess the certainty of the evidence.

MAIN RESULTS

We included 60 trials with 11,156 infants. Most trials were small (median sample size 145 infants). The main potential sources of bias were unclear reporting of methods for concealing allocation and masking caregivers or investigators in about half of the trials. The formulation of the probiotics varied across trials. The most common preparations contained Bifidobacterium spp., Lactobacillus spp., Saccharomyces spp., andStreptococcus spp., alone or in combination. Very preterm or very low birth weight infants Probiotics may reduce the risk of NEC (RR 0.54, 95% CI 0.46 to 0.65; I² = 17%; 57 trials, 10,918 infants; low certainty). The number needed to treat for an additional beneficial outcome (NNTB) was 33 (95% CI 25 to 50). Probiotics probably reduce mortality slightly (RR 0.77, 95% CI 0.66 to 0.90; I² = 0%; 54 trials, 10,484 infants; moderate certainty); the NNTB was 50 (95% CI 50 to 100). Probiotics probably have little or no effect on the risk of late-onset invasive infection (RR 0.89, 95% CI 0.82 to 0.97; I² = 22%; 49 trials, 9876 infants; moderate certainty). Probiotics may have little or no effect on neurodevelopmental impairment (RR 1.03, 95% CI 0.84 to 1.26; I² = 0%; 5 trials, 1518 infants; low certainty). Extremely preterm or extremely low birth weight infants Few data were available for extremely preterm or extremely low birth weight (ELBW) infants. In this population, probiotics may have little or no effect on NEC (RR 0.92, 95% CI 0.69 to 1.22, I² = 0%; 10 trials, 1836 infants; low certainty), all-cause mortality (RR 0.92, 95% CI 0.72 to 1.18; I² = 0%; 7 trials, 1723 infants; low certainty), or late-onset invasive infection (RR 0.93, 95% CI 0.78 to 1.09; I² = 0%; 7 trials, 1533 infants; low certainty). No trials provided data for measures of neurodevelopmental impairment in extremely preterm or ELBW infants.

AUTHORS' CONCLUSIONS

Given the low to moderate certainty of evidence for the effects of probiotic supplements on the risk of NEC and associated morbidity and mortality for very preterm or VLBW infants, and particularly for extremely preterm or ELBW infants, there is a need for further large, high-quality trials to provide evidence of sufficient validity and applicability to inform policy and practice.

Featured Prebiotic Agent: The Roles and Mechanisms of Direct and Indirect Prebiotic Activities of Lactoferrin and Its Application in Disease Control

Lactoferrin (LF) is a glycoprotein found in mammalian milk, and lactoferricin is a peptide derived from LF hydrolysate. Both LF and lactoferricin (LFcin) have diverse functions that could benefit mammals. Bovine LF (BLF) and BLFcin exhibit a wide range of antimicrobial activities, but most probiotic strains are relatively resistant to their antibacterial effects. BLF and BLF hydrolysate can promote the growth of specific probiotics depending on the culture conditions, the dose of BLF or BLF-related peptides, and the probiotic strains used. BLF supplementation has been shown to modulate several central molecular pathways or genes in Lacticaseibacillus rhamnosus GG under cold conditions, which may explain the prebiotic roles of BLF. LF alone or in combination with selected probiotics can help control bacterial infections or metabolic disorders, both in animal studies and in human clinical trials. Various LF-expressing probiotics, including those expressing BLF, human LF, or porcine LF, have been developed to facilitate the combination of LFs with specific probiotics. Supplementation with LF-expressing probiotics has positive effects in animal studies. Interestingly, inactivated LF-expressing probiotics significantly improved diet-induced nonalcoholic fatty liver disease (NAFLD) in a mouse model. This review highlights the accumulated evidence supporting the use of LF in combination with selected LF-resistant probiotics or LF-expressing probiotics in the field.

New insights into the pathogenesis of necrotizing enterocolitis and the dawn of potential therapeutics

Necrotizing enterocolitis (NEC) is a devastating gastrointestinal disorder in premature infants that causes significant morbidity and mortality. Research efforts into the pathogenesis of NEC have discovered a pivotal role for the gram-negative bacterial receptor, Toll-like receptor 4 (TLR4), in its development. TLR4 is activated by dysbiotic microbes within the intestinal lumen, which leads to an exaggerated inflammatory response within the developing intestine, resulting in mucosal injury. More recently, studies have identified that the impaired intestinal motility that occurs early in NEC has a causative role in disease development, as strategies to enhance intestinal motility can reverse NEC in preclinical models. There has also been broad appreciation that NEC also contributes to significant neuroinflammation, which we have linked to the effects of gut-derived pro-inflammatory molecules and immune cells which activate microglia in the developing brain, resulting in white matter injury. These findings suggest that the management of the intestinal inflammation may secondarily be neuroprotective. Importantly, despite the significant burden of NEC on premature infants, these and other studies have provided a strong rationale for the development of small molecules with the capability of reducing NEC severity in pre-clinical models, thus guiding the development of specific anti-NEC therapies. This review summarizes the roles of TLR4 signaling in the premature gut in the pathogenesis of NEC, and provides insights into optimal clinical management strategies based upon findings from laboratory studies.

Single-cell RNA sequencing of intestinal immune cells in neonatal necrotizing enterocolitis

PURPOSE

Necrotizing enterocolitis (NEC) causes fatal intestinal necrosis in neonates, but its etiology is unknown. We analyzed the intestinal immune response to NEC.

METHODS

Using single-cell RNA sequencing (scRNA-seq), we analyzed the gene expression profiles of intestinal immune cells from four neonates with intestinal perforation (two with NEC and two without NEC). Target mononuclear cells were extracted from the lamina propria of the resected intestines.

RESULTS

In all four cases, major immune cells, such as T cells (15.1-47.7%), B cells (3.1-19.0%), monocytes (16.5-31.2%), macrophages (1.6-17.4%), dendritic cells (2.4-12.2%), and natural killer cells (7.5-12.8%), were present in similar proportions to those in the neonatal cord blood. Gene set enrichment analysis showed that the MTOR, TNF-α, and MYC signaling pathways were enriched in T cells of the NEC patients, suggesting upregulated immune responses related to inflammation and cell proliferation. In addition, all four cases exhibited a bias toward cell-mediated inflammation, based on the predominance of T helper 1 cells.

CONCLUSION

Intestinal immunity in NEC subjects exhibited stronger inflammatory responses compared to non-NEC subjects. Further scRNA-seq and cellular analysis may improve our understanding of the pathogenesis of NEC.

2022 Fleming Prize Lecture: diet-microbe-host interaction in early life

The last decade has witnessed a meteoric rise in research focused on characterizing the human microbiome and identifying associations with disease risk. The advent of sequencing technology has all but eradicated gel-based fingerprinting approaches for studying microbial ecology, while at the same time traditional microbiological culture is undergoing a renaissance. Although multiplexed high-throughput sequencing is relatively new, the discoveries leading to this are nearly 50 years old, coinciding with the inaugural Microbiology Society Fleming Prize lecture. It was an honour to give the 2022 Fleming Prize lecture and this review will cover the topics from that lecture. The focus will be on the bacterial community in early life, beginning with term infants before moving on to infants delivered prematurely. The review will discuss recent work showing how human milk oligosaccharides (HMOs), an abundant but non-nutritious component of breast milk, can modulate infant microbiome and promote the growth of Bifidobacterium spp. This has important connotations for preterm infants at risk of necrotizing enterocolitis, a devastating intestinal disease representing the leading cause of death and long-term morbidity in this population. With appropriate mechanistic studies, it may be possible to harness the power of breast milk bioactive factors and infant gut microbiome to improve short- and long-term health in infants.

Effects of prophylactic probiotics supplementation on infants born very preterm or very low birth weight

OBJECTIVE

To evaluate the effects of guideline-driven prophylactic supplementation of a multi-strain neonatal intensive care unit-specific probiotic product on infants born very preterm (VP) or very low birth weight (VLBW).

STUDY DESIGN

A prospective cohort of 125 infants born in one year after implementation who received probiotics were compared to a retrospective cohort of eligible 126 VP or VLBW infants who did not receive probiotics. The primary outcome of interest was necrotizing enterocolitis (NEC).

RESULT

The incidence of NEC decreased from 6.3 to 1.6%. After adjusting for multiple variables, there were no significant differences in primary or other outcomes of interest; odds ratio (95% confidence interval) NEC 0.27 (0.05-1.33), death 0.76 (0.26-2.21) and late-onset sepsis 0.54 (0.18-1.63). No adverse effects related to probiotics supplementation were observed.

CONCLUSION

Although nonsignificant, prophylactic probiotics supplementation in infants born VP or VLBW was associated with reduction of NEC.

Molecular Mechanisms of Hyperoxia-Induced Neonatal Intestinal Injury

Oxygen therapy is important for newborns. However, hyperoxia can cause intestinal inflammation and injury. Hyperoxia-induced oxidative stress is mediated by multiple molecular factors and leads to intestinal damage. Histological changes include ileal mucosal thickness, intestinal barrier damage, and fewer Paneth cells, goblet cells, and villi, effects which decrease the protection from pathogens and increase the risk of necrotizing enterocolitis (NEC). It also causes vascular changes with microbiota influence. Hyperoxia-induced intestinal injuries are influenced by several molecular factors, including excessive nitric oxide, the nuclear factor-κB (NF-κB) pathway, reactive oxygen species, toll-like receptor-4, CXC motif ligand-1, and interleukin-6. Nuclear factor erythroid 2-related factor 2 (Nrf2) pathways and some antioxidant cytokines or molecules including interleukin-17D, n-acetylcysteine, arginyl-glutamine, deoxyribonucleic acid, cathelicidin, and health microbiota play a role in preventing cell apoptosis and tissue inflammation from oxidative stress. NF-κB and Nrf2 pathways are essential to maintain the balance of oxidative stress and antioxidants and prevent cell apoptosis and tissue inflammation. Intestinal inflammation can lead to intestinal damage and death of the intestinal tissue, such as in NEC. This review focuses on histologic changes and molecular pathways of hyperoxia-induced intestinal injuries to establish a framework for potential interventions.

Early antibiotics and risk for necrotizing enterocolitis in premature infants: A narrative review

While prompt initiation of antibiotics at birth due to concerns for early onset sepsis is common, it often leads to many preterm infants being exposed to treatment despite negative blood cultures. Such exposure to early antibiotics can impact the developing gut microbiome putting infants at increased risk of several diseases. Necrotizing enterocolitis (NEC), a devastating inflammatory bowel disease that affects preterm infants, is among the most widely studied neonatal disease that has been linked to early antibiotics. While some studies have demonstrated an increased risk of NEC, other studies have demonstrated seemingly contrary findings of decreased NEC with early antibiotics. Studies using animal models have also yielded differing findings of benefit vs. harm of early antibiotic exposure on subsequent NEC susceptibility. We thus sought to conduct this narrative review to help clarify the relationship between early antibiotics exposure and future risk of NEC in preterm infants. Our objectives are to: (1) summarize findings from human and animal studies that investigated the relationship between early antibiotics and NEC, (2) highlight important limitations of these studies, (3) explore potential mechanisms that can explain why early antibiotics may increase or decrease NEC risk, and (4) identify future directions for research.

Probiotics for prevention of necrotizing enterocolitis: Where do we stand?

In this review, we provide a historical perspective on probiotic use in preterm infants. We review recent data on the treatment effects of probiotics on necrotizing enterocolitis, sepsis, and mortality. We highlight guidance statements from professional societies and organizations, discussing key points within the context of the currently available evidence from both randomized trials and cohort studies. Finally, we summarize experiences from several North American centers that have reported on the routine use of probiotics, including our center. Our goal is to highlight some of the considerations and complexities surrounding routine probiotics use in preterm infants.

Current and future methods of probiotic therapy for necrotizing enterocolitis

Necrotizing enterocolitis (NEC) is a complex intestinal disease that primarily affects premature neonates. Given its significant mortality and morbidity, there is an urgent need to develop improved prophylactic measures against the disease. One potential preventative strategy for NEC is the use of probiotics. Although there has been significant interest for decades in probiotics in neonatal care, no clear guidelines exist regarding which probiotic to use or for which patients, and no FDA-approved products exist on the market for NEC. In addition, there is lack of agreement regarding the benefits of probiotics in neonates, as well as some concerns about the safety and efficacy of available products. We discuss currently available probiotics as well as next-generation probiotics and novel delivery strategies which may offer an avenue to capitalize on the benefits of probiotics, while minimizing the risks. Thus, probiotics may still prove to be an effective prevention strategy for NEC, although further product development and research is needed to support use in the preterm population.

Prebiotic activity of chitooligosaccharides and their ability to alleviate necrotizing enterocolitis in newborn rats

Chitooligosaccharides (COS) have many bioactive functions and favorable prospects in the fields of biomedicine and functional foods. In this study, COS was found to significantly improve the survival rate of neonatal necrotizing enterocolitis (NEC) model rats, alter the composition of the intestinal microbiota, inhibit the expression of inflammatory cytokines, and alleviate intestinal pathological injury. In addition, COS also increased the abundance of Akkermansia, Bacteroides, and Clostridium sensu stricto 1 in the intestines of normal rats (the normal rat model is more universal). The in vitro fermentation results found that COS was degraded by the human gut microbiota to promote the abundance of Clostridium sensu stricto 1 and produced numerous short-chain fatty acids (SCFAs). In vitro metabolomic analysis revealed that COS catabolism was associated with significant increases in 3-hydroxybutyrate acid and γ-aminobutyric acid. This study provides evidence for the potential of COS as a prebiotic in food products and to ameliorate NEC development in neonatal rats.

In Vivo Efficacy of Bacillus velezensis Isolated from Korean Gochang Bokbunja Vinegar against Carbapenem-Resistant Klebsiella pneumoniae Infections

Outbreaks of carbapenem-resistant Enterobacteriaceae (CRE), especially Klebsiella pneumoniae (CRKP), are commonly reported as severe infections in hospitals and long-term care settings, and their occurrence is increasing globally. Conventional antibiotics used for treating CRE have become ineffective due to resistance development. Furthermore, their safety issues restrict their availability and use for CRE treatment. Therefore, developing new drugs different from existing drugs to combat this deadly menace is urgently needed. Probiotics can be a potential option in this context, as probiotics' efficacy against a variety of infectious illnesses has already been well established. Here, we report the effect of the Bacillus velezensis strain isolated from Gochang Bokbunja vinegar in Korea on CRE infection using two mouse models. Data showed that pretreatment with B. velezensis significantly reduced body weight loss and mortality of CRKP-infected mice in the preventive model. The oral administration of B. velezensis in a therapeutic model also decreased the mortality and illness severity in CRKP-infected mice. Moreover, a two-week oral acute toxicity assay in guinea pigs did not reveal any aberrant clinical signs. Our findings demonstrate the potential effectiveness of our candidate probiotic strain, B. velezensis, against CRKP, suggesting that it could be used as an antimicrobial agent for treating CRKP-related infections.

A Retrospective Evaluation of the Diagnostic Performance of an Interdependent Pairwise MicroRNA Expression Analysis with a Mutation Panel in Indeterminate Thyroid Nodules

Background: The addition of genetic analysis to the evaluation of thyroid nodule fine-needle aspiration biopsy samples improves diagnostic accuracy of cytologically indeterminate thyroid nodules (ITNs) with Bethesda III or IV cytopathology. We previously reported the performance of a multiplatform molecular test, referred to in this study as MPTXv1, that includes a mutation panel (ThyGeNEXT^®) plus an algorithmic microRNA (miRNA) risk classifier (ThyraMIR^®). Complex interactions of growth-promoting and -suppressing miRNAs affect the phenotype. We previously demonstrated that accounting for these interactions with pairwise miRNA expression analysis improves the diagnosis of medullary thyroid carcinoma. In this study, we assess the impact of pairwise miRNA expression analysis on risk stratification of ITNs. Methods: Pairwise expression analysis of 11 miRNAs was performed on a training cohort of histopathology-proven benign nodules (n = 50) to define the mean and standard deviation of each pairwise analysis and create a Benign/Malignant Profiler (MPTXv2), deviations from which predicted the malignancy risk. Clinical validation of MPTXv2 was assessed using a cohort of 178 ITN (Bethesda III and IV) samples from a multicentered, blinded retrospective study, previously evaluated by MPTXv1. Results: Compared with MPTXv1, MPTXv2 significantly improved the test performance. The receiver operating characteristic (ROC) areas under the curve (AUC) increased from 0.85 to 0.97 (p < 0.001), and the diagnostic accuracy at the positive threshold increased significantly (p < 0.05) from 83% [95% confidence interval (CI) = 76-88] to 93% [CI = 89-96]. The significant improvement in the ROC AUC and the diagnostic accuracy was due to a strong statistical trend for improvement in specificity at the positive threshold. At the positive threshold, the specificity for MPTXv1 was 90% [CI = 84-95] and improved to 98% [CI = 94-99] for MPTXv2. Using the MPTXv2, the Moderate-Risk cohort decreased from 50 samples (28% of the cohort) to 24 samples (13% of the cohort). This 52% decrease is statistically significant (p < 0.001) and clinically meaningful. Conclusion: As compared with MPTXv1, pairwise miRNA expression analysis used in MPTXv2 significantly improved the diagnostic accuracy of ITN risk stratification and reduced the size of the Moderate-Risk group. Prospective trials are indicated to confirm these findings in a clinical practice setting.

Preterm Infant Fecal Microbiota and Metabolite Profiles Are Modulated in a Probiotic Specific Manner

OBJECTIVES

To compare the impact of two probiotic supplements on fecal microbiota and metabolites, as well as on gut inflammation in human milk-fed preterm infants.

METHODS

In this single-center observational cohort study, we assessed the effects of Bifidobacterium longum subsp. infantis or Lactobacillus reuteri supplementation on the infant gut microbiota by 16S rRNA gene sequencing and fecal metabolome by 1 H nuclear magnetic resonance spectroscopy. Fecal calprotectin was measured as a marker of enteric inflammation. Aliquots of human or donor milk provided to each infant were also assessed to determine human milk oligosaccharide (HMO) content.

RESULTS

As expected, each probiotic treatment was associated with increased proportions of the respective bacterial taxon. Fecal HMOs were significantly higher in L. reuteri fed babies despite similar HMO content in the milk consumed. Fecal metabolites associated with bifidobacteria fermentation products were significantly increased in B. infantis supplemented infants. Fecal calprotectin was lower in infants receiving B. infantis relative to L. reuteri ( P < 0.01, Wilcoxon rank-sum test) and was negatively associated with the microbial metabolite indole-3-lactate (ILA).

CONCLUSIONS

This study demonstrates that supplementing an HMO-catabolizing Bifidobacterium probiotic results in increased microbial metabolism of milk oligosaccharides and reduced intestinal inflammation relative to a noncatabolizing Lactobacillus probiotic in human milk-fed preterm infants. In this context, Bifidobacterium may provide greater benefit in human milk-fed infants via activation of the microbiota-metabolite-immune axis.

Regulatory T Cells in Development and Prediction of Necrotizing Enterocolitis in Preterm Neonates: A Scoping Review

Necrotizing enterocolitis (NEC) is a leading cause of mortality in premature infants. However, the pathophysiology and influence of regulatory T cells (Tregs) have not been sufficiently elucidated. We performed a scoping review to investigate current knowledge on the influence of Tregs in NEC, and to investigate the predictive value of Treg number in NEC development. Pubmed, Embase, Prospero and Cochrane Library were searched during December 2020. Primary research articles discussing Tregs and NEC development written in English were selected. Two reviewers screened title and abstract for relevance, after which full-text screening was performed. A total of 20 articles were selected—13 of the articles discussed studies performed in animal models, while 8 used human neonate data. One study discussed both animal and human data. It was shown that after NEC diagnosis or induction, Treg levels were decreased while Th17 levels were increased. No studies were found which investigated the predictive value of Treg number in NEC development. A reduced Treg level is found in animals and neonates with NEC. The question remains whether this effect is a factor on the causal pathway of NEC development or a bystander effect. Future research focusing on the pathophysiological timeline of NEC and the involvement of Tregs is required for better understanding of this disease.

Knockdown of TRPM7 attenuates apoptosis and inflammation in neonatal necrotizing enterocolitis model cell IEC-6 via modulating TLR4/NF-κB and MEK/ERK pathways

OBJECTIVES

Neonatal necrotizing enterocolitis (NEC) is the most common gastrointestinal critical illness in neonatal infants. TRPM7 reportedly plays a role in human inflammatory bowel disease (IBD) and colorectal cancer, but the role of TRPM7 in the pathogenesis of NEC remains vague.

MATERIALS AND METHODS

The expression of TRPM7 was determined in intestinal tissues of NEC patients and lipopolysaccharide (LPS)-induced IEC-6 cells. Subsequently, a loss-of-function assay was performed to assess the effects of TRPM7 on cell apoptosis and inflammatory response in IEC-6 cells after LPS induction. Furthermore, the modulation of TRPM7 on TLR4/NF-κB and MEK/ERK signaling pathways was validated.

RESULTS

The expression of TRPM7 was higher in the intestinal tissues of NEC patients compared with the normal human intestinal tissues. Moreover, the expression level of TRPM7 was elevated in LPS stimulation IEC-6 cells. Knockdown of TRPM7 enhanced cell viability and suppressed apoptosis, accompanied by the decreased Bax/Bcl-1 ratio and cleaved-caspase3 expression in LPS-induced IEC-6 cells. Additionally, TRPM7 silencing attenuated LPS-induced expressions and secretions of proinflammatory cytokines. Mechanistically, TRPM7 knockdown inhibited the TLR4/NF-κB activation, while enhancing the MEK/ERK activation in LPS-treated IEC-6 cells. Overexpression of TLR4 or inhibition of MEK attenuated the inhibitory effects of TRPM7 knockdown on LPS-induced apoptosis and inflammation in IEC-6 cells.

CONCLUSION

Knockdown of TRPM7 attenuated LPS-induced IEC-6 cell apoptosis and inflammation by modulating TLR4/NF-κB and MEK/ERK pathways.

Harnessing the microbiome to prevent global biodiversity loss

Global biodiversity loss and mass extinction of species are two of the most critical environmental issues the world is currently facing, resulting in the disruption of various ecosystems central to environmental functions and human health. Microbiome-targeted interventions, such as probiotics and microbiome transplants, are emerging as potential options to reverse deterioration of biodiversity and increase the resilience of wildlife and ecosystems. However, the implementation of these interventions is urgently needed. We summarize the current concepts, bottlenecks and ethical aspects encompassing the careful and responsible management of ecosystem resources using the microbiome (termed microbiome stewardship) to rehabilitate organisms and ecosystem functions. We propose a real-world application framework to guide environmental and wildlife probiotic applications. This framework details steps that must be taken in the upscaling process while weighing risks against the high toll of inaction. In doing so, we draw parallels with other aspects of contemporary science moving swiftly in the face of urgent global challenges.

Effect of Various Preterm Infant Milk Formulas on NEC-Like Gut Injury in Mice

Formula feeding is an important risk factor for the development of necrotizing enterocolitis in preterm infants. The potential harmful effects of different preterm formulas on the developing intestinal tract remain incompletely understood. Here we demonstrate that feeding newborn mouse pups with various preterm formulas resulted in differing effects on intestinal inflammation, apoptosis, and activation of the pro-inflammatory transcription factor NFκB. 16S rRNA sequencing revealed that each preterm formula resulted in significant gut microbial alterations that were different from dam-fed controls. Formula feeding with EleCare and Similac Special Care caused greater intestinal injury compared to NeoSure. Pre-treatment with Lactobacillus rhamnosus GG ameliorated severity of intestinal injury from EleCare and Similac Special Care. Our findings indicate that not all preterm formulas are the same, and different formulations can have varying effects on intestinal inflammation, apoptosis, and microbiome composition.

Nutrition and Immunity in Perinatal Hypoxic-Ischemic Injury

Perinatal hypoxia ischaemia (PHI), acute and chronic, may be associated with considerable adverse outcomes in the foetus and neonate. The molecular and cellular mechanisms of injury and repair associated with PHI in the perinate are not completely understood. Increasing evidence is mounting for the role of nutrients and bioactive food components in immune development, function and repair in PHI. In this review, we explore current concepts around the neonatal immune response to PHI with a specific emphasis on the impact of nutrition in the mother, foetus and neonate.

Antibacterial and anti-inflammatory effects of Lactobacillus reuteri in its biofilm state contribute to its beneficial effects in a rat model of experimental necrotizing enterocolitis

INTRODUCTION

Necrotizing enterocolitis (NEC) remains a significant surgical emergency in neonates. We have demonstrated the efficacy of Lactobacillus reuteri (Lr) in protecting against experimental NEC when administered as a biofilm by incubation with maltose loaded dextranomer microspheres. Lr possesses antimicrobial and anti-inflammatory properties. We developed mutant strains of Lr to examine the importance of its antimicrobial and anti-inflammatory properties in protecting the intestines from NEC.

METHODS

Premature rat pups were exposed to hypoxia/hypothermia/hypertonic feeds to induce NEC. To examine the importance of antimicrobial reuterin and anti-inflammatory histamine, pups received either native or mutant forms of Lr, in either its planktonic or biofilm states, prior to induction of NEC. Intestinal histology was examined upon sacrifice.

RESULTS

Compared to no treatment, administration of a single dose of Lr in its biofilm state significantly decreased the incidence of NEC (67% vs. 18%, p < 0.0001), whereas Lr in its planktonic state had no significant effect. Administration of reuterin-deficient or histamine-deficient forms of Lr, in either planktonic or biofilm states, resulted in significant loss of efficacy.

CONCLUSION

Antimicrobial and anti-inflammatory effects of Lr contribute to its beneficial effects against NEC. This suggests that both infectious and inflammatory components contribute to the etiology of NEC.

Infection prevention for extremely low birth weight infants in the NICU

Extremely preterm infants are particularly vulnerable to systemic infections secondary to their immature immune defenses, prolonged hospitalizations, delays in enteral feeding, early antibiotic exposure, and need for life-sustaining invasive interventions. There have been several evidence-based practices for infection prevention in this population, such as human milk feedings, utilization of "bundle checklists" and decolonization of pathogenic organisms. Other practices, such as the use of probiotics, human milk-derived fortifiers, and antifungal prophylaxis are more controversial and require further investigation regarding the risks and benefits of such interventions. This chapter examines the susceptibility of the preterm newborn infant to invasive infections and describes several strategies for infection prevention, along with the associated limitations of such practices. It also addresses the various gaps in our understanding of preventing infections in this population, and the need for additional large multi-center randomized controlled trials. Additionally, the role of the SARs-CoV-2 global pandemic and associated strategies for infection prevention in the NICU are discussed.

Maternal and infant probiotic administration for morbidity of very low birth weight infants: a three-arm randomized placebo-controlled trial

PURPOSE

To determine whether oral probiotic administration (1.5 × 10⁹ CFU/g Lacticaseibacillus paracasei subsp. paracasei) to breastfeeding mothers or to their very low birth weight (VLBW) infants reduces total serum bilirubin (TSB) level and increases weight gain of the infants.

METHODS

In this double-blind trial, breastfeeding mothers and their VLBW infants at 48-72 h of age were allocated into three groups using stratified block randomization; administrating probiotic to the mothers and placebo to their infants, probiotic to the infants and placebo to their mothers, or placebo to the both. The intervention continued for 28 days.

RESULTS

All 25 mothers and their 26 infants allocated into each group were fully followed up. There were three positive blood culture only in the placebo group. On the 3rd day of intervention, TSB level was not significantly different among the groups but on the 7th day, it was significantly lower in the both probiotic groups compared with the placebo group (mean difference  -2.4 mg/dL [95% confidence interval  -3.6 to  -1.2] in the both comparisons). Mean rank of infant weight gain during the first 7 days of intervention was significantly higher in the both maternal and infant probiotic groups compared with the placebo group (p = 0.007 and p = 0.003, respectively), but there was no statistically significant difference among the groups during the 8th-28th days.

CONCLUSION

Administration of Lacticaseibacillus paracasei to breastfeeding mothers of VLBW infants or to their infants reduces infant TSB level but has no significant effect on weight gain after the first week of the intervention.

TRIAL REGISTRATION

The Iranian Clinical Trials Registry IRCT20100414003706N38. protrospectively registered 24/01/2021.

The Use of Probiotics in Preterm Infants

Probiotics are live microorganisms that positively affect host health by altering the composition of the host microbiota. Gastrointestinal dysbiosis refers to adverse alterations of the intestinal flora and is associated with several diseases, including necrotizing enterocolitis, late-onset sepsis in preterm infants as well as atopic disease, colic, diabetes, and diarrhea in term infants. The risk factors for gastrointestinal dysbiosis are preterm birth, cesarean section delivery, and formula feeding, in contrast to term birth infants, vaginal delivery and breast milk feeding. Probiotics have been used to restore synbiosis in infants with gastrointestinal dysbiosis. Probiotics inhibit colonization of pathogenic bacteria in the gastrointestinal tract, thereby improving the barrier function of the gastrointestinal tract, and the immune function. In preterm infants, probiotics reduce mortality as well as rates of necrotizing enterocolitis and late-onset sepsis. The combined use of probiotics such as <i>Lactobacillus</i> and <i>Bifidobacterium</i> and the combination of probiotics with prebiotics yield better outcomes in the prevention of necrotizing enterocolitis than those achieved with a single pro- or prebiotic strain. However, the routine use of probiotics has been hindered by the lack of pharmaceutical-quality products, and a definite effect has yet to be demonstrated in preterm infants with a birth weight <1,000 g. Therefore, to reduce the risk of necrotizing enterocolitis in preterm infants, probiotics should be provided along with breast milk and other strategies aimed at preventing gastrointestinal dysbiosis.

Gut microbiota in various childhood disorders: Implication and indications

Gut microbiota has a significant role in gut development, maturation, and immune system differentiation. It exerts considerable effects on the child's physical and mental development. The gut microbiota composition and structure depend on many host and microbial factors. The host factors include age, genetic pool, general health, dietary factors, medication use, the intestine's pH, peristalsis, and transit time, mucus secretions, mucous immunoglobulin, and tissue oxidation-reduction potentials. The microbial factors include nutrient availability, bacterial cooperation or antagonism, and bacterial adhesion. Each part of the gut has its microbiota due to its specific characteristics. The gut microbiota interacts with different body parts, affecting the pathogenesis of many local and systemic diseases. Dysbiosis is a common finding in many childhood disorders such as autism, failure to thrive, nutritional disorders, coeliac disease, Necrotizing Enterocolitis, helicobacter pylori infection, functional gastrointestinal disorders of childhood, inflammatory bowel diseases, and many other gastrointestinal disorders. Dysbiosis is also observed in allergic conditions like atopic dermatitis, allergic rhinitis, and asthma. Dysbiosis can also impact the development and the progression of immune disorders and cardiac disorders, including heart failure. Probiotic supplements could provide some help in managing these disorders. However, we are still in need of more studies. In this narrative review, we will shed some light on the role of microbiota in the development and management of common childhood disorders.

Melatonin Alleviates Neonatal Necrotizing Enterocolitis by Repressing the Activation of the NLRP3 Inflammasome

Objective

Necrotizing enterocolitis (NEC) is one of the commonest gastrointestinal critical diseases in newborns. Several researches have proven the efficacy of melatonin (MEL) on NEC, but the latent mechanisms were ambiguous. We designed the current research to evaluate the function and mechanism of MEL on NEC in a neonatal mouse model.

Methods

The newborn mice were subjected to formula milk containing LPS and hypoxia to establish a NEC model and also intraperitoneally injected with MEL. During the experiment, all mice were closely monitored and weighed. The effect of MEL on the histopathological injury of the terminal ileum tissues, inflammation, and oxidative stress of serum in NEC mice was examined by hematoxylin-eosin (H&E) staining and ELISA. The effect of MEL on the NOD-like receptor family pyrin domain containing 3 (NLRP3) inflammasome was assessed via quantitative real-time PCR and Western blot.

Results

MEL intensified the survival rate and body weight in NEC mice. The H&E staining illustrated that MEL improved the histopathological injury in NEC mice. Moreover, MEL repressed the IL-1β, TNF-α, and MDA levels of serum and enhanced the SOD and GSH-Px levels of serum in NEC mice. We also discovered that MEL attenuated the mRNA and protein levels of NLRP3, Toll-like Receptor 4 (TLR4), NF-κB, and caspase-1 of the terminal ileum tissues in NEC mice.

Conclusion

Our research illuminated that MEL attenuated the severity of NEC via weakening the activation of the NLRP3 inflammasome.

Bifidobacterium longum Subspecies infantis Strain EVC001 Decreases Neonatal Murine Necrotizing Enterocolitis

Necrotizing enterocolitis (NEC) is a disease mainly of preterm infants with a 30-50% mortality rate and long-term morbidities for survivors. Treatment strategies are limited and have not improved in decades, prompting research into prevention strategies, particularly with probiotics. Recent work with the probiotic B. infantis EVC001 suggests that this organism may generate a more appropriate microbiome for preterm infants who generally have inappropriate gut colonization and inflammation, both risk factors for NEC. Experimental NEC involving Paneth cell disruption in combination with bacterial dysbiosis or formula feeding was induced in P14-16 C57Bl/6 mice with or without gavaged B. infantis. Following completion of the model, serum, small intestinal tissue, the cecum, and colon were harvested to examine inflammatory cytokines, injury, and the microbiome, respectively. EVC001 treatment significantly decreased NEC in a bacterial dysbiosis dependent model, but this decrease was model-dependent. In the NEC model dependent on formula feeding, no difference in injury was observed, but trending to significant differences was observed in serum cytokines. EVC001 also improved wound closure at six and twelve hours compared to the sham control in intestinal epithelial monolayers. These findings suggest that B. infantis EVC001 can prevent experimental NEC through anti-inflammatory and epithelial barrier restoration properties.

Evaluation of Risk and Preventive Factors for Necrotizing Enterocolitis in Premature Newborns. A Systematic Review of the Literature

Necrotizing enterocolitis (NEC) is a serious condition related to prematurity and the initiation of enteral feeding. In this article, we review the evidence published in recent years on necrotizing enterocolitis risk factors (prematurity, feeding with low-weight formula, existence of intestinal dysbiosis) and protective factors (human milk or donated milk supply, supplementation of human milk with oligosaccharides, probiotics administration, and the determination of disease predictive biomarkers). A systematic review was conducted of preventive, risk and predictive factors for necrotizing enterocolitis in neonates prior to 37 weeks' gestational age, based on a literature search for clinical trials, meta-analyses, randomized controlled trials and systematic reviews published between January 2018 and October 2021. For this purpose, the PubMed, MEDLINE, and Cochrane Library databases were consulted. The literature search obtained 113 articles, of which 19 were selected for further analysis after applying the inclusion and exclusion criteria. The conclusions drawn from this analysis were that adequate knowledge of risk factors that can be prevented or modified (such as alteration of the intestinal microbiota, oxidative stress, metabolic dysfunction at birth, or alteration of the immunity modulation) can reduce the incidence of NEC in premature infants. These factors include the supplementation of enteral nutrition with human milk oligosaccharides (with prebiotic and immunomodulatory effects), the combined administration of probiotics (especially the Lactobacillus spp and Bifidobacterium spp combination, which inhibits bacterial adhesion effects, improves the intestinal mucosa barrier function, strengthens the innate and adaptive immune system and increases the secretion of bioactive metabolites), the supplementation of human milk with lactoferrin and the use of donated milk fortified in accordance with the characteristics of the premature newborn. The determination of factors that can predict the existence of NEC, such as fecal calprotectin, increased TLR4 activity, and IL6 receptor, can lead to an early diagnosis of NEC. Although further studies should be conducted to determine the values of predictive biomarkers of NEC, and/or the recommended doses and strains of probiotics, lactoferrin or oligosaccharides, the knowledge acquired in recent years is encouraging.

Probiotics Regulating Inflammation via NLRP3 Inflammasome Modulation: A Potential Therapeutic Approach for COVID-19

Inflammasomes are cytoplasmic multiprotein complexes formed by the host's immune system as a response to microbial infection and cellular damage. Many studies have revealed various regulators of NOD-, LRR-, and pyrin domain-containing protein 3 (NLRP3) inflammasome activation, while it has been recently shown that NLRP3 is implicated in COVID-19 pathogenesis. At the same time, probiotics counteract the inflammatory process and modulate cytokine release, thus influencing both innate and adaptive immune systems. Herein, we review the immunomodulatory potential of probiotics on the assembly of NLRP3 inflammasome, as well as the pathophysiological mechanisms supporting the use of probiotic bacteria for SARS-CoV-2 infection management, presenting evidence from preclinical studies of the last decade: in vivo, ex vivo, and mixed trials. Data show that probiotics intake is related to NLRP3 inflammasome attenuation and lower levels of inflammation markers, highlighting the beneficial effects of probiotics on inflammatory conditions. Currently, none of the ongoing clinical trials evaluating the effectiveness of probiotics intake in humans with COVID-19 has been completed. However, evidence from preclinical studies indicates that probiotics may block virus invasion and replication through their metabolites, bacteriocins, and their ability to block Angiotensin-Converting Enzyme 2 (ACE2), and by stimulating the immune response through NLRP3 inflammasome regulation. In this review, the beneficial effects of probiotics in the inflammatory process through NLRP3 inflammasome attenuation are presented. Furthermore, probiotics may target SARS-CoV-2 both by blocking virus invasion and replication and by stimulating the immune response through NLRP3 inflammasome regulation. Heterogeneity of the results-due to, among others, different bacterial strains and their metabolites, forms, dosage, and experimental designs-indicates the need for more extensive research.

Recurrent late-onset neonatal sepsis traced to breast milk: A case report

Breast milk feeding is an important late-onset sepsis reduction strategy in the Neonatal Intensive Care Unit (NICU). However, multiple studies have reported transfer of bacteria-contaminated breast milk to infants. We describe a case of culture-positive breast milk resulting in persistent Enterococcus bacteremia in an infant. Beyond the development of an infant's innate and specific immunity as well as colonization of the gastrointestinal (GI) tract with commensal organisms, the risk of bacterial translocation from the GI tract into the bloodstream is shaped and modified by maternal health, birth history, and an infant's NICU course. While freezing and/or pasteurizing breast milk reduces or eliminates its bacterial load, it also diminishes its immunologic and nutritional benefits.

Malnutrition, poor post-natal growth, intestinal dysbiosis and the developing lung

In extremely preterm infants, poor post-natal growth, intestinal dysbiosis and bronchopulmonary dysplasia are common, and each is associated with long-term complications. The central hypothesis that this review will address is that these three common conditions are interrelated. Challenges to studying this hypothesis include the understanding that malnutrition and poor post-natal growth are not synonymous and that there is not agreement on what constitutes a normal intestinal microbiota in this evolutionarily new population. If this hypothesis is supported, further study of whether "correcting" intestinal dysbiosis in extremely preterm infants reduces postnatal growth restriction and/or bronchopulmonary dysplasia is indicated.

Effect and Safety of Saccharomyces boulardii for Neonatal Necrotizing Enterocolitis in Pre-term Infants: A Systematic Review and Meta-Analysis

BACKGROUND AND OBJECTIVE

Necrotizing enterocolitis (NEC) is one of the most common and urgent neonatal emergencies in the neonatal intensive care unit. This disease leads to considerable morbidity and mortality; it also imposes a huge financial burden on patient family and society. Thus, Treatment and prevention of NEC are crucial. This meta-analysis aims to investigate the effect and safety of Saccharomyces boulardii for NEC in pre-term infants.

METHODS

A comprehensive search was retrieved in six major databases. The search included randomized controlled trials (RCTs) reporting the incidence of NEC (stage ≥ II), sepsis, mortality, feeding intolerance, full feeding days, time to regain birth weight, days of hospitalization and adverse effects. The random model was used to calculate risk ratio (RR), the standard mean difference (SMD) and its 95% confidence interval (95% CI) between the S. boulardii group and control group. Statistical analyses were conducted using Cochrane systematic review software, Rev Man (version 5.3).

RESULTS

In total, 10 RCTs involving 1264 participants met the inclusion criteria. There were significant reductions in the incidence of NEC [RR = 0.56, 95% CI (0.36-0.89)], feeding intolerance [RR = 0.52, 95% CI (0.39-0.68)], full feeding days [SMD = -1.25, 95% CI (-2.06 to -0.45)] and hospitalization days [SMD = -1.33, 95% CI (-2.64 to -0.02)] in the study group compared with the control group. However, there were no significant differences in sepsis [RR = 0.84, 95% CI (0.61-1.17)], death [RR = 1.12, 95% CI (0.46-2.70)] and the time to regain birth weight [SMD = -0.93, 95% CI (-1.88 to 0.03)] between the two groups. The adverse effect of S. boulardii was not reported. The overall methodological quality was evaluated as moderate by the Cochrane Bias Risk Assessment Tool.

CONCLUSION

According to this evidence we recommend S. boulardii to prevent NEC, reduce the feeding intolerance, shorten the full feeding days and hospitalization days. However, S. boulardii might be invalid on the incidence of sepsis, mortality and the time to regain birth weight.

REGISTRATION

This review has been registered to the PROSPERO (International prospective register of systematic reviews) on 5 December 2019 (ID: CRD42019147896).

Probiotics for the Management of Sepsis: Advances in Animal Models and Intensive Care Unit Environments

Sepsis frequently leads to multiple organ failure and is a major cause of morbidity and mortality in critically ill patients. Although intensive care protocols and antibiotic therapy have improved sepsis treatment, specific management is lacking with respect to efficient protection from tissue damage and long-term outcomes. Probiotics are live microbes that modulate the immune system and inflammation and colonize the gut. In this narrative review, we have traced the evolution of the administration of probiotics in an animal model of sepsis and treatment alternatives in the intensive care unit setting. First, probiotics are categorized by species before describing their modulation of the microbiota, repair of tissue-specific damage, immune response, and molecular pathways to prevent complications. The impact on therapy for infant and adult patients is also addressed. Finally, we have emphasized the challenges and gaps in current studies as well as future perspectives for further investigation. The present review can open up avenues for new strategies that employ promising probiotic strains for the treatment of sepsis and discusses their ability to prevent disease-associated long-term complications.

Use of Probiotics in Preterm Infants

Probiotic products in the United States are available for use in the general category of dietary supplements, bypassing the rigor of the US Food and Drug Administration (FDA) approval process in safety, efficacy, and manufacturing standards. As a result, currently available probiotics lack FDA-approved drug labeling and cannot be marketed to treat or prevent disease in preterm infants, including necrotizing enterocolitis and late-onset sepsis. Despite lack of availability of a pharmaceutical-grade product, the number of preterm infants receiving probiotics in the United States and Canada is steadily increasing. According to recent reports from large collaborative databases in the United States, approximately 10% of extremely low gestational age neonates receive a probiotic preparation during their stay in the NICU, with wide variation in practice among units. In sum, more than 10 000 preterm infants have been enrolled in randomized clinical trials of probiotic supplementation worldwide. Methodologic differences among study protocols included different strains and combinations of therapy, masking of trials, and a priori definitions of the primary outcome measure. Large meta-analyses of these trials have demonstrated the efficacy of multiple-strain probiotics in reducing necrotizing enterocolitis and all-cause mortality, whereas the efficacy of single-strain probiotic preparations is less certain. In the absence of an appropriate medical-grade product in the United States, dietary supplement-grade probiotics, some of which have been the subject of recent recalls for contamination, are being prescribed. Given the lack of FDA-regulated pharmaceutical-grade products in the United States, conflicting data on safety and efficacy, and potential for harm in a highly vulnerable population, current evidence does not support the routine, universal administration of probiotics to preterm infants, particularly those with a birth weight of <1000 g.

Necrotizing Enterocolitis

Necrotizing enterocolitis (NEC) is an inflammatory disease affecting premature infants. Intestinal microbial composition may play a key role in determining which infants are predisposed to NEC and when infants are at highest risk of developing NEC. It is unclear how to optimize antibiotic therapy in preterm infants to prevent NEC and how to optimize antibiotic regimens to treat neonates with NEC. This article discusses risk factors for NEC, how dysbiosis in preterm infants plays a role in the pathogenesis of NEC, and how probiotic and antibiotic therapy may be used to prevent and/or treat NEC and its sequelae.

Gut Microbiota and Acute Diverticulitis: Role of Probiotics in Management of This Delicate Pathophysiological Balance

How can the knowledge of probiotics and their mechanisms of action be translated into clinical practice when treating patients with diverticular disease and acute diverticulitis? Changes in microbiota composition have been observed in patients who were developing acute diverticulitis, with a reduction of taxa with anti-inflammatory activity, such as Clostridium cluster IV, Lactobacilli and Bacteroides. Recent observations supported that a dysbiosis characterised by decreased presence of anti-inflammatory bacterial species might be linked to mucosal inflammation, and a vicious cycle results from a mucosal inflammation driving dysbiosis at the same time. An alteration in gut microbiota can lead to an altered activation of nerve fibres, and subsequent neuronal and muscular dysfunction, thus favoring abdominal symptoms' development. The possible role of dysbiosis and mucosal inflammation in leading to dysmotility is linked, in turn, to bacterial translocation from the lumen of the diverticulum to perivisceral area. There, a possible activation of Toll-like receptors has been described, with a subsequent inflammatory reaction at the level of the perivisceral tissues. Being aware that bacterial colonisation of diverticula is involved in the pathogenesis of acute diverticulitis, the rationale for the potential role of probiotics in the treatment of this disease becomes clearer. For this review, articles were identified using the electronic PubMed database through a comprehensive search conducted by combining key terms such as "gut microbiota", "probiotics and gut disease", "probiotics and acute diverticulitis", "probiotics and diverticular disease", "probiotics mechanism of action". However, the amount of data present on this matter is not sufficient to draw robust conclusions on the efficacy of probiotics for symptoms' management in diverticular disease.