Efficacy of different probiotic combinations on death and necrotizing enterocolitis in a premature rat model

Composition and evolutionary characterization of the gut microbiota in pigs

The intestinal microbiota plays significant role in the physiology and functioning of host organisms. However, there is limited knowledge of the composition and evolution of microbiota-host relationships from wild ancestors to modern domesticated species. In this study, the 16S rRNA gene V3-V4 in the intestinal contents of different pig breeds was analyzed and was compared using high-throughput sequencing. This identified 18 323 amplicon sequence variants, of which the Firmicutes and Actinobacteria phyla and Bifidobacterium and Allobaculum genera were most prevalent in wild pigs (WP). In contrast, Proteobacteria and Firmicutes predominated in Chinese Shanxi Black pigs (CSB), while Firmicutes were the most prevalent phylum in Large White pigs (LW) and Iberian pigs (IB), followed by Bacteroidetes in IB and Proteobacteria in LW. At the genus level, Shigella and Lactobacillus were most prevalent in CSB and LW, while Actinobacillus and Sarcina predominated in IB. Differential gene expression together with phylogenetic and functional analyses indicated significant differences in the relative abundance of microbial taxa between different pig breeds. Although many microbial taxa were common to both wild and domestic pigs, significant diversification was observed in bacterial genes that potentially influence host phenotypic traits. Overall, these findings suggested that both the composition and functions of the microbiota were closely associated with domestication and the evolutionary changes in the host. The members of the microbial communities were vertically transmitted in pigs, with evidence of co-evolution of both the hosts and their intestinal microbial communities. These results enhance our understanding and appreciation of the complex interactions between intestinal microbes and hosts and highlight the importance of applying this knowledge in agricultural and microbiological research.

Prevention and treatment of antibiotics-associated adverse effects through the use of probiotics: A review

BACKGROUND

The human gut hosts a diverse microbial community, essential for maintaining overall health. However, antibiotics, commonly prescribed for infections, can disrupt this delicate balance, leading to antibiotic-associated diarrhea, inflammatory bowel disease, obesity, and even neurological disorders. Recognizing this, probiotics have emerged as a promising strategy to counteract these adverse effects.

AIM OF REVIEW

This review aims to offer a comprehensive overview of the latest evidence concerning the utilization of probiotics in managing antibiotic-associated side effects.

KEY SCIENTIFIC CONCEPTS OF REVIEW

Probiotics play a crucial role in preserving gut homeostasis, regulating intestinal function and metabolism, and modulating the host immune system. These mechanisms serve to effectively alleviate antibiotic-associated adverse effects and enhance overall well-being.

Identification and evaluation of probiotic potential of Bifidobacterium breve AHC3 isolated from chicken intestines and its effect on necrotizing enterocolitis (NEC) in newborn SD rats

Necrotizing enterocolitis (NEC) is a severe intestinal disease of the newborn infants, associated with high morbidity and mortality. It has been reported that Bifidobacterium could protect the intestinal barrier function and reduce the risk of NEC. This study aimed to evaluate the probiotic potential of Bifidobacterium strains isolated from the chicken intestines and its effect on necrotizing enterocolitis in newborn SD rats. Out of 32 isolates, B. breve AHC3 not only exhibited excellent probiotic potential, including tolerance to artificial simulated gastric conditions, adhesion to HT-29 cells, antioxidant capacity and antibacterial activity, but also possessed reliable safety. Additionally, NEC model was established to further investigate the effect of B. breve AHC3 on necrotizing enterocolitis in newborn SD rats. It was illustrated that administration of B. breve AHC3 significantly not only reduced the incidence of NEC (from 81.25% to 34.38%) (P< 0.05), but also alleviated the severity of ileal injury (P< 0.05). Compared with NEC model, B. breve AHC3 could significantly decrease the level of proinflammatory factor TNF-α (P< 0.05) and increase the level of antiinflammatory factor IL-10 (P< 0.05) in the ileum of NEC rats. Through the intervention of B. breve AHC3, the gray value of inducible nitric oxide synthase (iNOS) in intestinal tissue of NEC rats was significantly reduced (P< 0.05). It was indicated that B. breve AHC3 exhibited prominent probiotic potential and reliable safety. In the neonatal SD rat model of NEC, B. breve AHC3 had an available protective effect on the intestinal injury of NEC, which might be related to reducing the inflammatory reaction in the ileum and inhibiting the expression of iNOS in intestinal tissue cells. B. breve AHC3 could be used as a potential treatment for human NEC.

Effects of systemic Bifidobacterium longum and Lactobacillus rhamnosus probiotics on the ligature-induced periodontitis in rat

Background/purpose

Probiotics might be beneficial in preventing periodontitis. Effects of Bifidobacterium and Lactobacillus on periodontitis were examined using the ligature-induced rat model.

Materials and methods

Thirty-five male Sprague-Dawley rats were divided into control, ligation, Bifidobacterium longum (BL986), Lactobacillus rhamnosus (LRH09), and combination groups. Periodontitis was induced in maxillary second molars. From the day before ligation, phosphate-buffered saline (for control and ligation groups) or probiotics (2 × 109 CFU/g for probiotic groups) were fed daily. On day 8, gingival mRNA expressions for interleukin (IL)-1β, IL-6, tissue necrosis factor (TNF)-α, IL-10, and NF-κB were determined via qPCR. Micro-computed tomography (μCT) and histomorphometry were employed to examine periodontal destruction.

Results

Compared to the ligation group, mRNA of IL-1β, TNF-α, IL-6, and NF-κB in probiotic groups were significantly decreased, but IL-10 was increased. Besides, the IL-10 was more significant in the combination group than in single-use group. Through μCT, the cementoenamel junction (CEJ)-to-bone distance and trabecular separation in combination group were less than that in ligation group, although the bone volume fraction and trabecular number/thickness showed an increase in three probiotic groups. Histopathologically, the combination group had significantly smaller gingival inflammatory cell-infiltrated area and CEJ-to-epithelium distance than the ligation group and the group with BL986 or LRH09. Additionally, the CEJ-to-bone distance was significantly smaller in the combination group than in the ligation and BL986 groups.

Conclusion

Systemic combination of BL986 and LRH09 had a synergistic effect on enhancing IL-10 and ameliorating the induced experimental periodontitis, although the single-use still presented partially alleviative effects.

Effects of different combinations of probiotics on rheology, microstructure, and moisture distribution of soy materials-based yogurt

The effects of different probiotics on the texture, rheological properties, microstructure, and water distribution of yogurt fermented with soy powder, soy isolate protein powder, soy umbilical powder, and soy whey as the main raw materials were studied. The soy materials-based yogurt fermented by Danisco mixed probiotic reached the end of fermentation after 4 h, which significantly shortened the fermentation time compared with other probiotic combinations. The fermentation with Danisco mixed probiotic and Kefir mixed probiotic respectively resulted in good texture and a denser and more homogeneous microstructure, which was consistent with the sensory evaluation results. Both fermentations had a high water holding capacity of 90.92% and 78.30%, respectively, in agreement with the results of moisture distribution tests. However, the elastic and viscous behaviors were weaker at certain shear frequency. This study achieved a high value-added utilization of soy whey and the development of a new soy materials-based yogurt that met the consumption needs of people with lactose intolerance and high cholesterol. PRACTICAL APPLICATION: In this study, high value-added utilization of soy whey was realized, which solved the problems of resource waste and environmental pollution. Meanwhile, the research and development of soy materials-based yogurt provided another nutritional and healthy consumption demand for lactose intolerant people.

Intestinal ‘Infant-Type’ Bifidobacteria Mediate Immune System Development in the First 1000 Days of Life

Immune system maturation begins early in life, but few studies have examined how early-life gut microbiota colonization educates the neonatal immune system. Bifidobacteria predominate in the intestines of breastfed infants and metabolize human milk oligosaccharides. This glycolytic activity alters the intestinal microenvironment and consequently stimulates immune system maturation at the neonatal stage. However, few studies have provided mechanistic insights into the contribution of ‘infant-type’ Bifidobacterium species, especially via metabolites such as short-chain fatty acids. In this review, we highlight the first 1000 days of life, which provide a window of opportunity for infant-type bifidobacteria to educate the neonatal immune system. Furthermore, we discuss the instrumental role of infant-type bifidobacteria in the education of the neonatal immune system by inducing immune tolerance and suppressing intestinal inflammation, and the potential underlying mechanism of this immune effect in the first 1000 days of life. We also summarize recent research that suggests the administration of infant-type bifidobacteria helps to modify the intestinal microecology and prevent the progress of immune-mediated disorders.

Recent Development of Probiotic Bifidobacteria for Treating Human Diseases

Bifidobacterium is a non-spore-forming, Gram-positive, anaerobic probiotic actinobacterium and commonly found in the gut of infants and the uterine region of pregnant mothers. Like all probiotics, Bifidobacteria confer health benefits on the host when administered in adequate amounts, showing multifaceted probiotic effects. Examples include B. bifidum, B. breve, and B. longum, common Bifidobacterium strains employed to prevent and treat gastrointestinal disorders, including intestinal infections and cancers. Herein, we review the latest development in probiotic Bifidobacteria research, including studies on the therapeutic impact of Bifidobacterial species on human health and recent efforts in engineering Bifidobacterium. This review article would provide readers with a wholesome understanding of Bifidobacteria and its potentials to improve human health.

Colonization of fecal microbiota from patients with neonatal necrotizing enterocolitis exacerbates intestinal injury in germfree mice subjected to necrotizing enterocolitis-induction protocol via alterations in butyrate and regulatory T cells

BACKGROUND

Necrotizing enterocolitis (NEC) remains a life-threatening disease in neonates. Numerous studies have shown a correlation between the intestinal microbiota and NEC, but the causal link remains unclear. This study aimed to demonstrate the causal role of gut microbiota in NEC and explore potential mechanisms involved.

METHODS

Eighty-one fecal samples from patients with NEC and eighty-one matched controls (matched to the NEC infants by gestational age, birth weight, date of birth, mode of delivery and feeding patterns) were collected. To explore if altered gut microbiota contributes to the pathogenesis of NEC, fecal microbiota transplantation (FMT) was carried out in germ-free (GF) mice prior to a NEC-induction protocol that included exposure to hypoxia and cold stress. Butyric acid was also administered to demonstrate its role in NEC. The fecal microbiota from patients and mice were analyzed by 16S rRNA gene sequencing analysis. Short chain fatty acid (SCFA) levels were measured by gas chromatography-mass spectrometry (GC-MS). The ontogeny of T cells and regulatory T cells (T_regs) in lamina propria mononuclear cells (LPMC) from the ileum of patients and mice were isolated and analyzed by flow cytometry.The transcription of inflammatory cytokines was quantified by qRT-PCR.

RESULTS

NEC patients had increased Proteobacteria and decreased Firmicutes and Bacteroidetes compared to fecal control samples, and the level of butyric acid in the NEC group was lower than the control group. FMT in GF mice with samples from NEC patients achieved a higher histological injury scores when compared to mice that received FMT with control samples. Alterations in microbiota and butyrate levels were maintained in mice following FMT. The ratio of T_reg/CD4⁺T (T_helper) cells was reduced in both NEC patients and mice modeling NEC following FMT.

CONCLUSIONS

The microbiota was found to have NEC and the microbial butyrate-T_reg axis was identified as a potential mechanism for the observed effects.

Role of Bifidobacteria on Infant Health

Bifidobacteria are among the predominant microorganisms during infancy, being a dominant microbial group in the healthy breastfed infant and playing a crucial role in newborns and infant development. Not only the levels of the Bifidobacterium genus but also the profile and quantity of the different bifidobacterial species have been demonstrated to be of relevance to infant health. Although no definitive proof is available on the causal association, reduced levels of bifidobacteria are perhaps the most frequently observed alteration of the intestinal microbiota in infant diseases. Moreover, Bifidobacterium strains have been extensively studied by their probiotic attributes. This review compiles the available information about bifidobacterial composition and function since the beginning of life, describing different perinatal factors affecting them, and their implications on different health alterations in infancy. In addition, this review gathers exhaustive information about pre-clinical and clinical studies with Bifidobacterium strains as probiotics in neonates.

Current Status of Probiotics for Preterm Infants

Probiotics have been shown to reduce the risk of all-cause mortality, necrotizing enterocolitis (NEC ≥ stage II), late onset sepsis (LOS), and feeding intolerance in preterm infants. Considering the substantial health burden imposed by these conditions, the importance of probiotics in preterm infants cannot be overemphasized. Based on the data from experimental studies, and systematic reviews of randomized controlled trials (RCTs) and non-RCTs, the uptake of this intervention in neonatal medicine has been increasing over the last few years. However, many are still hesitating to adopt this intervention for various reasons, including concerns about probiotic sepsis, product quality, and lack of clarity on optimal strain/s or their combinations. Some question the validity of meta-analyses of studies involving different probiotic strains or their combinations because probiotics effects are considered to be strain-specific. Some of the early concerns about probiotics in preterm infants have been shown to be unjustified. However, the resistance to probiotics continues in many neonatal units around the world. The future of probiotics for preterm infants depends on continued efforts to develop high-quality probiotic products using stringent quality control, improving access to such products, and robust head-to-head comparisons to know the optimal strains or their combinations. Monitoring for adverse effects such as probiotic sepsis and development of antibiotic resistance is crucial. The authors review the current status of probiotics in preterm infants and discuss the scope for further research in this field.

Lactobacillus reuteri in Its Biofilm State Improves Protection from Experimental Necrotizing Enterocolitis

Necrotizing enterocolitis (NEC) is a devastating disease predominately found in premature infants that is associated with significant morbidity and mortality. Despite decades of research, medical management with broad spectrum antibiotics and bowel rest has remained relatively unchanged, with no significant improvement in patient outcomes. The etiology of NEC is multi-factorial; however, gastrointestinal dysbiosis plays a prominent role in a neonate's vulnerability to and development of NEC. Probiotics have recently emerged as a new avenue for NEC therapy. However, current delivery methods are associated with potential limitations, including the need for at least daily administration in order to obtain any improvement in outcomes. We present a novel formulation of enterally delivered probiotics that addresses the current limitations. A single enteral dose of Lactobacillus reuteri delivered in a biofilm formulation increases probiotic survival in acidic gastric conditions, increases probiotic adherence to gastrointestinal epithelial cells, and reduces the incidence, severity, and neurocognitive sequelae of NEC in experimental models.

Development of probiotic yogurt: effect of strain combination on nutritional, rheological, organoleptic and probiotic properties

Seven combinations of yogurt; C1 [yogurt starter culture (YSC)], T1, [YSC + Lactobacillus acidophilus (LA)], T2 [YSC + Bifidobacterium bifidum (BB)], T3 [YSC + Lactobacillus plantarum (LP)], T4 [YSC + Lactobacillus casei (LC)], T5 [YSC + LA + BB] and T6 [YSC + LP + LC] were developed. Nutritional [proximate and minerals], rheological [total soluble solids (TSS), pH, titratable acidity (TA), water holding capacity, synersis, viscosity] organoleptic and probiotic properties [viability, acid tolerance, bile salt tolerance] were assessed with standard methods. Nutritional composition differed significantly among samples except for the iron and zinc (P < 0.05). Yogurt containing LP as single or in combination with LC resulted in significantly higher ash, protein, calcium and phosphorous level. Probiotic combination also significantly affected the rheological properties of yogurts (P < 0.05). Yogurt with LP and LC as single or in combination lead to significantly higher TSS and viscosity while significantly low syneresis, whereas yogurt with LA as single or in combination resulted in low pH and high TA (P < 0.05). Interestingly, combination of LA and BB increased TSS, reduced pH and syneresis as compare to these bacteria as single probiotic source. Panel experts found yogurt with LP more flavourful. Combination of multi-strain and multi-species probiotic resulted in improved texture but we found no significant difference in overall acceptability. Combination of probiotic strains also resulted in better probiotic potential with multi-species combination found to be even more effective. BB seemed more stable than three other probiotic strains. The present study can be helpful to dairy industry in developing new probiotic products and may provide a rational for selecting a combination of probiotic strains.

Characterization of the bacterial microbiota composition and evolution at different intestinal tract in wild pigs (Sus scrofa ussuricus)

Commensal microorganisms are essential to the normal development and function of many aspects of animal biology, including digestion, nutrient absorption, immunological development, behaviors, and evolution. The specific microbial composition and evolution of the intestinal tracts of wild pigs remain poorly characterized. This study therefore sought to assess the composition, distribution, and evolution of the intestinal microbiome of wild pigs. For these analyses, 16S rRNA V3-V4 regions from five gut sections prepared from each of three wild sows were sequenced to detect the microbiome composition. These analyses revealed the presence of 6,513 operational taxonomic units (OTUs) mostly distributed across 17 phyla and 163 genera in these samples, with Firmicutes and Actinobacteria being the most prevalent phyla of microbes present in cecum and jejunum samples, respectively. Moreover, the abundance of Actinobacteria in wild pigs was higher than that in domestic pigs. At the genus level the Bifidobacterium and Allobaculum species of microbes were most abundant in all tested gut sections, with higher relative abundance in wild pigs relative to domestic pigs, indicating that in the process of pig evolution, the intestinal microbes also evolved, and changes in the intestinal microbial diversity could have been one of the evolutionary forces of pigs. Intestinal microbial functional analyses also revealed the microbes present in the small intestine (duodenum, jejunum, and ileum) and large intestine (cecum and colon) of wild pigs to engage distinct metabolic spatial structures and pathways relative to one another. Overall, these results offer unique insights that would help to advance the current understanding of how the intestinal microbes interact with the host and affect the evolution of pigs.

Effects of Bifidobacterium infantis on cytokine-induced neutrophil chemoattractant and insulin-like growth factor-1 in the ileum of rats with endotoxin injury

BACKGROUND

The digestive tract is the maximal immunizing tissue in the body, and mucosal integrity and functional status of the gut is very important to maintain a healthy organism. Severe infection is one of the most common causes of gastrointestinal dysfunction, and the pathogenesis is closely related to endotoxemia and intestinal barrier injury. Bifidobacterium is one of the main probiotics in the human body that is involved in digestion, absorption, metabolism, nutrition, and immunity. Bifidobacterium plays an important role in maintaining the intestinal mucosal barrier integrity. This study investigated the protective mechanism of Bifidobacterium during ileal injury in rats.

AIM

To investigate the effects of Bifidobacterium on cytokine-induced neutrophil chemoattractant (CINC) and insulin-like growth factor 1 (IGF-1) in the ileum of rats with endotoxin injury.

METHODS

Preweaning rats were randomly divided into three groups: Control (group C), model (group E) and treatment (group T). Group E was intraperitoneally injected with lipopolysaccharide (LPS) to create an animal model of intestinal injury. Group T was intragastrically administered Bifidobacterium suspension 7 d before LPS. Group C was intraperitoneally injected with normal saline. The rats were killed at 2, 6 or 12 h after LPS or physiological saline injection to collect ileal tissue samples. The expression of ileal CINC mRNA was evaluated by reverse transcription-polymerase chain reaction (RT-PCR), and expression of ileal IGF-1 protein and mRNA was detected by immunohistochemistry and RT-PCR, respectively.

RESULTS

The ileum of rats in Group C did not express CINC mRNA, ileums from Group E expressed high levels, which was then significantly decreased in Group T (F = 23.947, P < 0.05). There was no significant difference in CINC mRNA expression at different times (F = 0.665, P > 0.05). There was a high level of IGF-1 brown granules in ileal crypts and epithelial cells in Group C, sparse staining in Group E, and dark, dense brown staining in Group T. There was a significant difference between Groups C and E and Groups E and T (P < 0.05). There was no significant difference in IGF-1 protein expression at different times (F = 1.269, P > 0.05). IGF-1 mRNA expression was significantly different among the three groups (P < 0.05), though not at different times (F = 0.086, P > 0.05).

CONCLUSION

Expression of CINC mRNA increased in the ileum of preweaning rats with endotoxin injury, and exogenous administration of Bifidobacterium reduced CINC mRNA expression. IGF-1 protein and mRNA expression decreased in the ileum of preweaning rats with endotoxin injury, and exogenous administration of Bifidobacterium prevented the decrease in IGF-1 expression. Bifidobacterium may increase IGF-1 expression and enhance intestinal immune barrier function in rats with endotoxin injury.

An enhanced Lactobacillus reuteri biofilm formulation that increases protection against experimental necrotizing enterocolitis

One significant drawback of current probiotic therapy for the prevention of necrotizing enterocolitis (NEC) is the need for at least daily administration because of poor probiotic persistence after enteral administration, increasing the risk of the probiotic bacteria causing bacteremia or sepsis if the intestines are already compromised. We previously showed that the effectiveness of Lactobacillus reuteri ( Lr) in preventing NEC is enhanced when Lr is grown as a biofilm on the surface of dextranomer microspheres (DM). Here we sought to test the efficacy of Lr administration by manipulating the Lr biofilm state with the addition of biofilm-promoting substances (sucrose and maltose) to DM or by mutating the Lr gtfW gene (encoding an enzyme central to biofilm production). Using an animal model of NEC, we determined that Lr adhered to sucrose- or maltose-loaded DM significantly reduced histologic injury, improved host survival, decreased intestinal permeability, reduced intestinal inflammation, and altered the gut microbiome compared with Lr adhered to unloaded DM. These effects were abolished when DM or GtfW were absent from the Lr inoculum. This demonstrates that a single dose of Lr in its biofilm state decreases NEC incidence. Importantly, preloading DM with sucrose or maltose further enhances Lr protection against NEC in a GtfW-dependent fashion, demonstrating the tunability of the approach and the potential to use other cargos to enhance future probiotic formulations. NEW & NOTEWORTHY Previous clinical trials of probiotics to prevent necrotizing enterocolitis have had variable results. In these studies, probiotics were delivered in their planktonic, free-living form. We have developed a novel probiotic delivery system in which Lactobacillus reuteri (Lr) is delivered in its biofilm state. In a model of experimental necrotizing enterocolitis, this formulation significantly reduces intestinal inflammation and permeability, improves survival, and preserves the natural gut microflora compared with the administration of Lr in its free-living form.

Vitamin A and Retinoic Acid Exhibit Protective Effects on Necrotizing Enterocolitis by Regulating Intestinal Flora and Enhancing the Intestinal Epithelial Barrier

BACKGROUND

Exaggerated inflammation that characterizes necrotizing enterocolitis (NEC) is caused by the invasion of pathogens through an immature intestinal barrier. Vitamin A (VA) and retinoic acid (RA) play important roles in the growth of epithelial tissue and in modulating immune function.

OBJECTIVE

To investigate the roles of VA and RA in the development of NEC.

METHODS

Levels of serum retinol in patients and in a NEC mouse model were detected with high-performance liquid chromatography. Bacterial communities of NEC mice treated with VA or PBS were detected by high-throughput sequencing. In vitro and in vivo, levels of inflammatory factors were measured by ELISA and RT-PCR, and expression levels of claudin-1, occludin, and ZO-1 were detected by Western blotting. Transepithelial electrical resistance (TEER) was measured in Caco-2 cell monolayers.

RESULTS

The level of VA in the NEC patients was lower than in the control patients. In the NEC mice that were treated with VA versus PBS, the proportion of Escherichia-Shigella was lower, while the abundance of Bacteroides was markedly higher. Both in vivo and in vitro, the levels of inflammatory factors were significantly reduced, while the expression levels of claudin-1, occludin, and ZO-1 were increased, after the VA and RA treatments. Meanwhile, TEER was increased and lipopolysaccharide-induced damage was reduced in Caco-2 cell monolayers after RA treatment.

CONCLUSIONS

These results suggest that VA may regulate intestinal flora, alleviate inflammatory reactions, and enhance the intestinal epithelial barrier in NEC. Thus, VA may be an effective drug for providing protection against NEC in newborns.

Effects of probiotics on experimental necrotizing enterocolitis: a systematic review and meta-analysis

BackgroundMeta-analyses of randomized controlled trials (RCTs) suggest that probiotics decrease the risk of necrotizing enterocolitis (NEC) in preterm infants. Many animal RCTs have evaluated probiotics for preventing NEC. We systematically reviewed the literature on this topic.MethodsThe protocol for systematic review of animal intervention studies (SYRCLE) was followed. Medline, Embase, ISI Web of Science, e-abstracts from the Pediatric Academic Society meetings, and other neonatal conferences were searched in December 2015 and August 2016. RCTs comparing probiotics vs. placebo/no probiotic were included.ResultsA total of 29 RCTs were included (Rats: 16, Mice: 7, Piglets: 3, Quail: 2, Rabbit: 1; N~2,310), with 21 reporting on histopathologically confirmed NEC; remaining 8 assessed only pathways of probiotic benefits. Twenty of the 21 RCTs showed that probiotics significantly reduced NEC. Pooling of data was possible for 16/21 RCTs. Meta-analysis using random-effects model showed that probiotics significantly decreased the risk of NEC (203/641 (31.7%) vs. 344/571 (60.2%); relative risk: 0.51; 95% confidence interval (CI): 0.42-0.62; P<0.00001; I2=44%; number needed to treat: 4; 95% CI: 2.9, 4.3).ConclusionProbiotics significantly reduced NEC via beneficial effects on immunity, inflammation, tissue injury, gut barrier, and intestinal dysbiosis.

Multiple strains probiotics appear to be the most effective probiotics in the prevention of necrotizing enterocolitis and mortality: An updated meta-analysis

BACKGROUND

Some oral probiotics have been shown to prevent necrotizing enterocolitis (NEC) and decrease mortality effectively in preterm very low birth weight (PVLBW) infants. However, it is unclear whether a single probiotic or a mixture of probiotics is most effective for the prevention of NEC.

OBJECTIVE

A meta-analysis was conducted by reviewing the most up to date literature to investigate whether multiple strains probiotics are more effective than a single strain in reducing NEC and death in PVLBW infants.

DATA SOURCES

Relevant studies were identified by searches of the MEDLINE, EMBASE, and Cochrane CENTRAL databases, from 2001 to 2016.

DATA EXTRACTION AND SYNTHESIS

The inclusion criteria were randomized controlled trials of any enteral probiotic supplementation that was initiated within the first 7 days and continued for at least 14 days in preterm infants (≤ 34 weeks' gestation) and/or those of a birth weight ≤1500 g.

RESULTS

A total of 25 trials (n = 7345 infants) were eligible for inclusion in the meta-analysis using a fixed-effects model. Multiple strains probiotics were associated with a marked reduction in the incidence of NEC, with a pooled OR of 0.36 (95% CI, 0.24-0.53; P < .00001). Single strain probiotic using Lactobacillus species had a borderline effect in reducing NEC (OR of 0.60; 95% CI 0.36-1.0; P = .05), but not mortality. Multiple strains probiotics had a greater effectiveness in reducing mortality and were associated with a pooled OR of 0.58 (95% CI, 0.43-0.79; P = .0006). Trials using single strain of Bifidobacterium species and Saccharomyces boulardii did not reveal any beneficial effects in terms of reducing NEC or mortality.

CONCLUSION

This updated report found that multiple strains probiotics appear to be the most feasible and effective strategy for the prevention of NEC and reduction of mortality in PVLBW neonates. Further clinical trials should focus on which probiotic combinations are most effective.

Impact of probiotics on necrotizing enterocolitis

A large number of randomized placebo-controlled clinical trials and cohort studies have demonstrated a decrease in the incidence of necrotizing enterocolitis with administration of probiotic microbes. These studies have prompted many neonatologists to adopt routine prophylactic administration of probiotics while others await more definitive studies and/or probiotic products with demonstrated purity and stable numbers of live organisms. Cross-contamination and inadequate sample size limit the value of further traditional placebo-controlled randomized controlled trials. Key areas for future research include mechanisms of protection, optimum probiotic species or strains (or combinations thereof) and duration of treatment, interactions between diet and the administered probiotic, and the influence of genetic polymorphisms in the mother and infant on probiotic response. Next generation probiotics selected based on bacterial genetics rather than ease of production and large cluster-randomized clinical trials hold great promise for NEC prevention.

Probiotics in early life: a preventative and treatment approach

Microbial colonization of the infant gut plays a key role in immunological and metabolic pathways impacting human health. Since the maturation of the gut microbiota coincides with early life development, failure to develop a health compatible microbiota composition may result in pathology and disease in later life. Probiotics are live microorganisms that, when administered in adequate amounts, confer a health benefit on the host. Maternal transfer of microorganisms is possible during pregnancy and lactation, and the mother's diet and microbiota can influence that of her offspring. Furthermore, pre-term birth, Caesarean section birth, formula feeding, antibiotic use, and malnutrition have been linked to dysbiosis, which in turn is associated with several pathologies such as necrotizing enterocolitis, inflammatory bowel diseases, antibiotic associated diarrhea, colic, and allergies. Thus, early life should represent a preferred stage of life for probiotic interventions. In this context, they could be regarded as a means to 'program' the individual for health maintenance, in order to prevent pathologies associated with dysbiosis. In order to elucidate the mechanisms underlying the benefits of probiotic administration, pre-clinical studies have been conducted and found an array of positive results such as improved microbial composition, intestinal maturation, decreased pathogenic load and infections, and improved immune response. Moreover, specific probiotic strains administered during the perinatal period have shown promise in attenuating severity of necrotizing enterocolitis. The mechanisms elucidated suggest that probiotic interventions in early life can be envisaged for disease prevention in both healthy offspring and offspring at risk of chronic disease.

Bosom Buddies: The Symbiotic Relationship Between Infants and Bifidobacterium longum ssp. longum and ssp. infantis. Genetic and Probiotic Features

The intestinal microbiota is a complex community that plays an important role in human health from the initial steps of its establishment. Its microbial composition has been suggested to result from selective pressures imposed by the host and is modulated by competition among its members. Bifidobacterium longum is one of the most abundant species of the Bifidobacterium genus in the gut microbiota of healthy breast-fed infants and adults. The recent advancements of 'omics techniques have facilitated the genetic and functional studies of different gut microbiota members. They have revealed the complex genetic pathways used to metabolize different compounds that likely contribute to the competitiveness and persistence of B. longum in the colon. The discovery of a genomic island in B. longum ssp. infantis that encodes specific enzymes for the metabolism of human milk oligosaccharides suggests a specific ecological adaptation. Moreover, B. longum is widely used as probiotic, and beneficial effects in infant health have been reported in several studies.

Harvesting the benefits of biofilms: A novel probiotic delivery system for the prevention of necrotizing enterocolitis

BACKGROUND/PURPOSE

Probiotics reduce the incidence of necrotizing enterocolitis (NEC) albeit only when administered at high frequency (at least daily). We have developed a novel probiotic delivery system in which probiotics are grown as a biofilm on microspheres, allowing enhanced efficacy with only a single treatment.

METHODS

Neonatal rats were subjected to experimental NEC. Pups received a single enteral dose of: (1) vehicle only, (2) unloaded microspheres, (3) MRS (broth)-loaded microspheres, (4) Lactobacillus reuteri, (5) L. reuteri grown on unloaded microspheres, or (6) L. reuteri grown on MRS-loaded microspheres. Intestinal injury was graded histologically and intestinal permeability determined by serum levels of enterally administered fluorescein isothiocyanate-labeled dextran.

RESULTS

69% of untreated pups developed NEC, whereas 32% of pups treated with L. reuteri grown as a biofilm on unloaded microspheres (p=0.009) and 33% of pups treated with L. reuteri grown as a biofilm on MRS-loaded microspheres (p=0.005) developed NEC. No other group had a significant reduction in NEC. Furthermore, pups treated with L. reuteri grown as a biofilm had significantly reduced intestinal permeability.

CONCLUSIONS

A single dose of Lactobacillus biofilm grown on biocompatible microspheres significantly reduces NEC incidence and severity. This novel probiotic delivery system may be beneficial in the prevention of NEC in the future.

Probiotics and Innate and Adaptive Immune Responses in Premature Infants

Premature infants are at increased risk for morbidity and mortality due to necrotizing enterocolitis (NEC) and sepsis. Probiotics decrease the risk of NEC and death in premature infants; however, mechanisms of action are unclear. A wide variety of probiotic species have been evaluated for potential beneficial properties in vitro, in animal models, and in clinical trials of premature infants. Although there is variation by species and even strain, common mechanisms of protection include attenuation of intestinal inflammation, apoptosis, dysmotility, permeability, supplanting other gut microbes through production of bacteriocins, and more effective use of available nutrients. Here, we review the most promising probiotics and what is known about their impact on the innate and adaptive immune response.

Bifidobacterium breve prevents necrotising enterocolitis by suppressing inflammatory responses in a preterm rat model

Necrotising enterocolitis (NEC) is associated with inflammatory responses and barrier dysfunction in the gut. In this study, we investigated the effect of Bifidobacterium breve M-16V on factors related to NEC development using an experimental rat model. Caesarean-sectioned rats were given formula milk with or without B. breve M-16V by oral gavage thrice daily, and experimental NEC was induced by exposing the rats to hypoxic conditions. Naturally delivered rats that were reared by their mother were used as healthy controls. The pathological score of NEC and the expression of molecules related to inflammatory responses and the barrier function were assessed in the ileum. B. breve M-16V reduced the pathological scores of NEC and resulted in some improvement in survivability. B. breve M-16V suppressed the increased expression of molecules related to inflammation and barrier function that resulted from NEC induction. B. breve M-16V normalised Toll-like receptor (TRL)4 expression and enhanced TLR2 expression. Our data suggest that B. breve M-16V prevents NEC development by modulating TLR expressions and suppressing inflammatory responses in a rat model.

The Role of Immunonutrients in the Prevention of Necrotizing Enterocolitis in Preterm Very Low Birth Weight Infants

Necrotizing enterocolitis (NEC) is a critical intestinal emergency condition, which mainly occurs in preterm very low birth weight (PVLBW) infants. Despite remarkable advances in the care of PVLBW infants, with considerable improvement of the survival rate in recent decades, the incidence of NEC and NEC-related mortality have not declined accordingly. The fast progression from nonspecific signs to extensive necrosis also makes primary prevention the first priority. Recently, increasing evidence has indicated the important role of several nutrients in primary prevention of NEC. Therefore, the aim of this review is to summarize some potential immunomodulatory nutrients in the prevention of NEC, including bovine colostrum, probiotics, prebiotics (e.g., human milk oligosaccharides), long chain polyunsaturated fatty acids, and amino acids (glutamine, cysteine and N-acetylcysteine, l-arginine and l-citrulline). Based on current research evidence, probiotics are the most documented effective method to prevent NEC, while others still require further investigation in animal studies and clinical randomized controlled trials.

Oral administration of surfactant protein-a reduces pathology in an experimental model of necrotizing enterocolitis

OBJECTIVES

Necrotizing enterocolitis (NEC) frequently results in significant morbidity and mortality in premature infants. Others reported that mice deficient in pulmonary surfactant protein-A (SP-A) born and raised in a nonhygienic environment succumb to significant gastrointestinal tract pathology, and enteral administration of purified SP-A significantly reduced mortality. We hypothesized that oral administration of purified SP-A can ameliorate pathology in an experimental model of neonatal NEC.

METHODS

Experimental NEC was induced in newborn Sprague-Dawley rat pups by daily formula gavage and intermittent exposure to hypoxia. Purified human SP-A (5 μg/day) was administered by oral gavage. After 4 days, surviving pups were sacrificed, and intestinal pathology was assessed by histological examination of distal terminal ileal sections. Intestinal levels of inflammatory cytokines (IL-1β, IFN-γ, and TNF-α) were assessed by enzyme-linked immunosorbent assay and levels of Toll-like receptor 4 (TLR4) by Western analysis.

RESULTS

Sixty-one percent of the gavaged rat pups that survived to day 4 met the criteria for experimental NEC after hypoxia, whereas treatment with SP-A significantly reduced mortality and assessment of NEC. Intestinal levels of proinflammatory cytokines were significantly increased in pups exposed to hypoxia. Administration of SP-A to pups exposed to hypoxia significantly reduced IL-1β and TNF-α levels, but had little effect on elevated levels of IFN-γ. SP-A treatment of hypoxia-exposed pups significantly reduced expression of intestinal TLR4, key in NEC pathogenesis.

CONCLUSIONS

In a rat model of experimental neonatal NEC, oral administration of SP-A reduces intestinal levels of proinflammatory cytokines and TLR4 protein and ameliorates adverse outcomes associated with gastrointestinal pathologies.

Postnatal high-protein diet improves learning and memory in premature rats via activation of mTOR signaling

PURPOSE

The present study investigated whether a high-protein diet affects spatial learning and memory in premature rats via modulation of mammalian target of rapamycin (mTOR) signaling.

METHODS

Pre- and full-term Sprague-Dawley pups were fed a normal (18% protein) or high-protein (30% protein) diet (HPD) for 6 or 8 weeks after weaning. Spatial learning and memory were tested in the Morris water maze at week 6 and 8. The activation of mTOR signaling pathway components was evaluated by western blotting.

RESULTS

Spatial memory performance of premature rats consuming a normal and HPD was lower than that of full-term rats on the same diet at 6 weeks, and was associated with lower levels of ribosomal protein S6 kinase p70 subtype (p70S6K) and initiation factor 4E-binding protein 1 (4EBP1) phosphorylation in the hippocampus. Spatial memory was improved in 8-week-old premature rats on an HPD as compared to those on a normal diet. Premature rats on an HPD had p70S6K and 4EBP1 phosphorylation levels in the hippocampus that were comparable to those of full-term rats on an HPD.

CONCLUSION

Long-term consumption of a protein-rich diet can restore the impairment in learning and memory in pre-term rats via upregulation of mTOR/p70S6K signaling.

The role of intestinal epithelial barrier function in the development of NEC

The intestinal epithelial barrier plays an important role in maintaining host health. Breakdown of intestinal barrier function is known to play a role in many diseases such as infectious enteritis, idiopathic inflammatory bowel disease, and neonatal inflammatory bowel diseases. Recently, increasing research has demonstrated the importance of understanding how intestinal epithelial barrier function develops in the premature neonate in order to develop strategies to promote its maturation. Optimizing intestinal barrier function is thought to be key to preventing neonatal inflammatory bowel diseases such as necrotizing enterocolitis. In this review, we will first summarize the key components of the intestinal epithelial barrier, what is known about its development, and how this may explain NEC pathogenesis. Finally, we will review what therapeutic strategies may be used to promote optimal development of neonatal intestinal barrier function in order to reduce the incidence and severity of NEC.

Bifidobacterium longum subsp. infantis in experimental necrotizing enterocolitis: alterations in inflammation, innate immune response, and the microbiota

BACKGROUND

Probiotics decrease the risk of necrotizing enterocolitis (NEC). We sought to determine the impact of Bifidobacterium longum subsp. infantis (B. infantis) in the established rat model of NEC.

METHODS

Rat pups delivered 1 d prior to term gestation were assigned to one of three groups: dam fed (DF), formula fed (FF), or fed with formula supplemented with 5 × 10(6) CFU B. infantis per day (FF+Binf). Experimental pups were exposed to hypoxia and cold stress. Ileal tissue was examined for pathology and expression of inflammatory mediators, antimicrobial peptides, and goblet-cell products. Ceca were assessed for bacterial composition by analysis of the 16S rRNA sequence.

RESULTS

Administration of B. infantis significantly reduced the incidence of NEC, decreased expression of Il6, Cxcl1, Tnfa, Il23, and iNOS, and decreased expression of the antimicrobial peptides Reg3b and Reg3g. There was significant microbial heterogeneity both within groups and between experiments. The cecal microbiota was not significantly different between the FF and FF+Binf groups. Bifidobacteria were not detected in the cecum in significant numbers.

CONCLUSION

In the rat model, the inflammation associated with NEC was attenuated by administration of probiotic B. infantis. Dysbiosis was highly variable, precluding determination of the precise role of the microbiota in experimental NEC.

Probiotics and prebiotics in neonatal necrotizing enterocolitis: New opportunities for translational research

Neonatal necrotizing enterocolitis (NEC) in premature infants has been recognized as a defined disease entity for at least four decades. Although survival has increased due to the advent of more sophisticated intensive care, incidence and long term health impacts due to NEC remain unchanged and no preventive therapy is currently available. Different probiotic strains of bacteria have been examined in their ability to prevent NEC with varied but encouraging results. Undigestable prebiotic sugars known to promote the growth of probiotic bacteria in the colon have been used in neonates with no clear benefit. The literature on NEC and probiotics is now cluttered with more reviews and meta-analyses than number of clinical trials. On the other hand, significant new information is available on microbiota and their impact on gut immunity. This review attempts to reiterate the risk factors of NEC and the pathogenesis of NEC with special reference to gut permeability. The reader is then introduced to gut microbiota, uniqueness and differences among probiotic strains, and how multiple resident flora talk to each other in the community setting in the human gut. After presenting a concise review of available clinical research results, the reader is challenged to question as to why no precise answer is available at present. Some modalities to examine the complex microflora and changes in the neonatal gut are then proposed including non-invasive methods and mathematical modeling. The review concludes by attracting the reader's attention to known immunomodulators of inflammation and injury. Justice to this review will be done only if the readers, clinical, and basic science investigators from multiple fields gather courage for a paradigm shift and embark on understanding the pathophysiology of the disease and attempt to discern the difference from equally preterm, equally vulnerable neonates that do not develop NEC. Learning about the developing microbiota in neonatal gut and its immunological impacts on the host in the face of many variables will provide a leap in our pursuit to select better, if not the best candidate probiotics, and put them to work against this stubborn disease that continues to take a toll on our precious neonates and the society.

Prevention of necrotizing enterocolitis in preterm very low birth weight infants: is it feasible?

Necrotizing enterocolitis (NEC) is still one of the most catastrophic intestinal emergencies in preterm very low-birth weight infants. Primary prevention of NEC should be the priority, since NEC frequently progresses from nonspecific signs, to extensive necrosis within a matter of hours with medical or surgical treatment, making successful treatment and secondary prevention difficult to achieve. Currently available strategies for primary prevention of NEC include antenatal glucocorticosteroids, breast milk feeding, cautious feeding strategy, fluid restriction and probiotics. Nonetheless, based on current research evidence, mixed flora probiotics, and/or breast milk feeding, would appear to be the most effective feasible methods in the prevention of NEC at present.