Gut Microbiome Developmental Patterns in Early Life of Preterm Infants: Impacts of Feeding and Gender

Gut microbiota plays a key role in multiple aspects of human health and disease, particularly in early life. Distortions of the gut microbiota have been found to correlate with fatal diseases in preterm infants, however, developmental patterns of gut microbiome and factors affecting the colonization progress in preterm infants remain unclear. The purpose of this prospective longitudinal study was to explore day-to-day gut microbiome patterns in preterm infants during their first 30 days of life in the neonatal intensive care unit (NICU) and investigate potential factors related to the development of the infant gut microbiome. A total of 378 stool samples were collected daily from 29 stable/healthy preterm infants. DNA extracted from stool was used to sequence the V4 region of the 16S rRNA gene region for community analysis. Operational taxonomic units (OTUs) and α-diversity of the community were determined using QIIME software. Proteobacteria was the most abundant phylum, accounting for 54.3% of the total reads. Result showed shift patterns of increasing Clostridium and Bacteroides, and decreasing Staphylococcus and Haemophilus over time during early life. Alpha-diversity significantly increased daily in preterm infants after birth and linear mixed-effects models showed that postnatal days, feeding types and gender were associated with the α-diversity, p< 0.05–0.01. Male infants were found to begin with a low α-diversity, whereas females tended to have a higher diversity shortly after birth. Female infants were more likely to have higher abundance of Clostridiates, and lower abundance of Enterobacteriales than males during early life. Infants fed mother’s own breastmilk (MBM) had a higher diversity of gut microbiome and significantly higher abundance in Clostridiales and Lactobacillales than infants fed non-MBM. Permanova also showed that bacterial compositions were different between males and females and between MBM and non-MBM feeding types. In conclusion, infant postnatal age, gender and feeding type significantly contribute to the dynamic development of the gut microbiome in preterm infants.     

Early Oxygen-Utilization and Brain Activity in Preterm Infants

The combined monitoring of oxygen supply and delivery using Near-InfraRed spectroscopy (NIRS) and cerebral activity using amplitude-integrated EEG (aEEG) could yield new insights into brain metabolism and detect potentially vulnerable conditions soon after birth. The relationship between NIRS and quantitative aEEG/EEG parameters has not yet been investigated. Our aim was to study the association between oxygen utilization during the first 6 h after birth and simultaneously continuously monitored brain activity measured by aEEG/EEG. Forty-four hemodynamically stable babies with a GA < 28 weeks, with good quality NIRS and aEEG/EEG data available and who did not receive morphine were included in the study. aEEG and NIRS monitoring started at NICU admission. The relation between regional cerebral oxygen saturation (rScO₂) and cerebral fractional tissue oxygen extraction (cFTOE), and quantitative measurements of brain activity such as number of spontaneous activity transients (SAT) per minute (SAT rate), the interval in seconds (i.e. time) between SATs (ISI) and the minimum amplitude of the EEG in μV (min aEEG) were evaluated. rScO₂ was negatively associated with SAT rate (β=-3.45 [CI=-5.76- -1.15], p=0.004) and positively associated with ISI (β=1.45 [CI=0.44-2.45], p=0.006). cFTOE was positively associated with SAT rate (β=0.034 [CI=0.009-0.059], p=0.008) and negatively associated with ISI (β=-0.015 [CI=-0.026- -0.004], p=0.007). Oxygen delivery and utilization, as indicated by rScO₂ and cFTOE, are directly related to functional brain activity, expressed by SAT rate and ISI during the first hours after birth, showing an increase in oxygen extraction in preterm infants with increased early electro-cerebral activity. NIRS monitored oxygenation may be a useful biomarker of brain vulnerability in high-risk infants.     

布拉酵母对炎症性肠病的治疗作用

炎症性肠病包括溃疡性结肠炎和克罗恩病, 其病因与发病机制尚未完全明确。大量研究表明, 肠道微生物在炎症性肠病的发生、发展中发挥重要作用。布拉酵母是一种有益于人体健康的肠道微生物, 研究发现能有效改善炎症性肠病症状, 可能与其抑制肠道致病菌、增强肠屏障功能、调节肠道黏膜免疫反应等有关。     

布拉酵母菌联合孟鲁斯特钠治疗变应性鼻炎的疗效观察

目的探讨布拉酵母菌联合孟鲁斯特钠治疗变应性鼻炎的临床疗效。方法将患儿随机分为治疗组与对照组,每组35例,两组患儿均用糠酸莫米松鼻喷剂早晨喷鼻1次,1喷/次。对照组用孟鲁司特钠咀嚼片2~5岁4 mg,6~12岁5 mg,12岁10 mg每晚睡前口服。治疗组在对照组基础上联合布拉酵母菌散剂1.0 g/次,2次/d,口服,4周1个疗程。结果两组患儿治疗后VAS评分均比治疗前降低,治疗组评分前后差异有统计学意义(P0.01),治疗后组间比较差异有统计学意义(P0.01),两组患儿随访6个月后与治疗结束时比较差异无统计学意义(P0.05)。治疗组与对照组患儿在总有效率和复发率的比较上差异均有统计学意义(P0.05)。结论布拉酵母菌联合孟鲁斯特钠治疗变应性鼻炎的临床疗效明显。     

Development of the Preterm Gut Microbiome in Twins at Risk of Necrotising Enterocolitis and Sepsis

The preterm gut microbiome is a complex dynamic community influenced by genetic and environmental factors and is implicated in the pathogenesis of necrotising enterocolitis (NEC) and sepsis. We aimed to explore the longitudinal development of the gut microbiome in preterm twins to determine how shared environmental and genetic factors may influence temporal changes and compared this to the expressed breast milk (EBM) microbiome. Stool samples (n = 173) from 27 infants (12 twin pairs and 1 triplet set) and EBM (n = 18) from 4 mothers were collected longitudinally. All samples underwent PCR-DGGE (denaturing gradient gel electrophoresis) analysis and a selected subset underwent 454 pyrosequencing. Stool and EBM shared a core microbiome dominated by Enterobacteriaceae, Enterococcaceae, and Staphylococcaceae. The gut microbiome showed greater similarity between siblings compared to unrelated individuals. Pyrosequencing revealed a reduction in diversity and increasing dominance of Escherichia sp. preceding NEC that was not observed in the healthy twin. Antibiotic treatment had a substantial effect on the gut microbiome, reducing Escherichia sp. and increasing other Enterobacteriaceae.This study demonstrates related preterm twins share similar gut microbiome development, even within the complex environment of neonatal intensive care. This is likely a result of shared genetic and immunomodulatory factors as well as exposure to the same maternal microbiome during birth, skin contact and exposure to EBM. Environmental factors including antibiotic exposure and feeding are additional significant determinants of community structure, regardless of host genetics.     

常规剂量奥美拉唑治疗早产儿喂养不耐受的疗效研究

目的:探讨常规剂量奥美拉唑治疗早产儿喂养不耐受的疗效及对血清胃泌素(gastrin,GAS)的影响.方法:选取60例出现喂养不耐受的早产患儿随机分为2组,对照组30例给予常规处理,治疗组30例在常规治疗基础上于生后第4天开始给予奥美拉唑注射液静脉滴注(0.7mg/kg·d),1次/d,连用5天.采用放射免疫分析法测定治疗组血清胃泌素水平.结果:治疗组胃潴留及腹胀症状消失时间、恢复至出生体重所需日龄、足量胃肠道喂养时间、2周末奶量与对照组比较有显著差异(P＜0.01).治疗组血清GAS水平较对照组明显升高,差异有显著性(P＜0.05).结论:奥美拉唑促进早产儿胃泌素分泌,治疗早产儿喂养不耐受有显著疗效,未见不良反应,为早产儿喂养不耐受的治疗提供了新的治疗方法.     

布拉酵母对小儿重症肺炎患儿肠黏膜屏障功能的影响

目的 探讨布拉酵母对小儿重症肺炎患儿肠黏膜屏障功能的影响。方法 将90例重症肺炎患儿按随机数字表分为对照组和观察组各45例。对照组患儿采用常规治疗,观察组患儿在常规治疗的同时加用布拉酵母治疗1周。比较两组患儿治疗前后血浆Ｄ-乳酸及肠型脂肪酸结合蛋白变化情况、胃肠功能障碍及腹泻发生率以及患儿不良反应。结果 治疗1周后,两组患儿血浆D-乳酸和肠型脂肪酸结合蛋白水平均低于治疗前（均P<0.01）,且不同时间点观察组指标水平下降幅度大于对照组（均P<0.01）。观察组患儿胃肠功能障碍发生率为6.7％、对照组为22.2％;观察组患儿腹泻发生率为15.6%,对照组为33.3%,二者比较差异均有统计学意义（均P<0.05）。观察组患儿无药物不良反应发生。结论 布拉酵母对重症肺炎患儿肠黏膜屏障具有保护作用,能减少胃肠功能障碍及腹泻发生率。     

Plasma Cytokine Levels Fall in Preterm Newborn Infants on Nasal CPAP with Early Respiratory Distress

Introduction

Early nCPAP seems to prevent ventilator-induced lung injury in humans, although the pathophysiological mechanisms underlying this beneficial effect have not been clarified yet.

Objective

To evaluate plasma levels IL-1β, IL-6, IL-8, IL-10, and TNF-α immediately before the start of nCPAP and 2 hours later in preterm infants.

Methods

Prospective cohort including preterm infants with 28 to 35 weeks gestational age with moderate respiratory distress requiring nCPAP. Extreme preemies, newborns with malformations, congenital infections, sepsis, surfactant treatment, and receiving ventilatory support in the delivery room were excluded. Blood samples were collected right before and 2 hours after the start of nCPAP.

Results

23 preterm infants (birth weight 1851±403 grams; GA 32.3±1.7 weeks) were treated with nCPAP. IL-1β, IL-10, TNF-α levels were similar, IL-8 levels were reduced in 18/23 preterm infants and a significant decrease in IL-6 levels was observed after 2 hours of nCPAP. All newborns whose mothers received antenatal steroids had lower cytokine levels at the onset of nCPAP than those whose mothers didn’t receive it; this effect was not sustained after 2 hours of nCPAP.

Conclusion

Early use nCPAP is not associated with rising of plasma pro-inflammatory cytokines and it seems to be a less harmful respiratory strategy for preterm with moderate respiratory distress.     

Neutrophil Chemotaxis in Cord Blood of Term and Preterm Neonates Is Reduced in Preterm Neonates and Influenced by the Mode of Delivery and Anaesthesia

Bacterial infections, even without any perinatal risk factors, are common in newborns, especially in preterm neonates. The aim of this study was to evaluate possible impairment of neutrophil chemotaxis in term and preterm neonates compared with adults as well as neonates with different modes of delivery and anaesthesia. We analysed the expression of the adhesion molecule L-Selectin as well as shape change, spontaneous and N-formyl-methionyl-leucyl-phenylalanine (fMLP)-induced transmigration of neutrophils in a flow cytometric assay of chemotaxis after spontaneous delivery with Cesarian Section (CS) under spinal anaesthesia (mepivacaine, sufentanil), epidural anaesthesia (ropivacaine or bupivacaine, sufentanil) or general anaesthesia (ketamine, thiopental, succinylcholine). Chemokinesis was higher (p=0.008) in cord blood neutrophils than in the adult ones, whereas those could be more stimulated by fMLP (p=0.02). After vaginal delivery neutrophils showed a higher spontaneous and fMLP-stimulated chemotactic response compared to neonates after CS without labor. Comparing different types of anaesthesia for CS, spinal anaesthesia resulted in less impairment on chemotaxis than general anaesthesia or epidural anaesthesia. The new flow cytometric assay of neutrophil chemotaxis is an appropriate and objective method to analyse functional differences even in very small volumes of blood, essential in neonatology. Term neonates do not show reduced chemotaxis compared to adults. Preterm neonates present with reduced chemotaxis and chemokinesis, confirming the well known deficits in their neutrophil function. The side effects of maternal drugs on the neonatal immune system have to be considered especially when the immune response is already impaired, as in preterm infants.     

早产儿语言发展的影响因素及其干预对策

早产儿的语言发展受到多种因素的影响,可能导致他们在词汇、语法、语音等方面出现发展滞后或障碍。本文首先简述了影响早产儿语言发展的生物学和环境因素的研究进展,其中生物学因素包括早产程度、体重和性别、新生儿发病率和疾病严重程度等,环境因素则包括新生儿重症监护室的环境、家庭中的语言环境和社会因素等。在明确这些影响因素的基础上,本文强调了早期评估和早期干预是优化早产儿语言发育效果的关键步骤,并分析了具体的干预对策,例如生理和神经干预、优化新生儿重症监护室（NICU）环境、增强家庭语言互动、多学科合作和社会支持等。此综述旨在探讨影响早产儿语言发展的各种因素,并总结出有效的早期干预措施,为其提供更为全面的语言发展支持。     

布拉酵母菌防治肠道疾病的研究进展

布拉酵母菌(Saccharomyces boulardii)是一种从印尼荔枝中分离出的益生菌,广泛用于肠道疾病的防治,本研究根据近年来的文献,对布拉酵母菌在防治肠道疾病中的研究进展进行了综述.     

Genotypic and physiological characterization of Saccharomyces boulardii, the probiotic strain of Saccharomyces cerevisiae

Saccharomyces boulardii, a yeast that was isolated from fruit in Indochina, has been used as a remedy for diarrhea since 1950 and is now a commercially available treatment throughout Europe, Africa, and South America. Though initially classified as a separate species of Saccharomyces, recent publications have shown that the genome of S. boulardii is so similar to Saccharomyces cerevisiae that the two should be classified as conspecific. This raises the question of the distinguishing molecular and phenotypic characteristics present in S. boulardii that make it perform more effectively as a probiotic organism compared to other strains of S. cerevisiae. This investigation reports some of these distinguishing characteristics including enhanced ability for pseudohyphal switching upon nitrogen limitation and increased resistance to acidic pH. However, these differences did not correlate with increased adherence to epithelial cells or transit through mouse gut. Pertinent characteristics of the S. boulardii genome such as trisomy of chromosome IX, altered copy number of a number of individual genes, and sporulation deficiency have been revealed by comparative genome hybridization using oligonucleotide-based microarrays coupled with a rigorous statistical analysis. The contributions of the different genomic and phenotypic features of S. boulardii to its probiotic nature are discussed.     

Influence of pH conditions on the viability of Saccharomyces boulardii yeast

Saccharomyces boulardii is a probiotic with proven health benefits. However its survival is challenged by gastrointestinal transit, and a ratio between 1 and 3% of living yeast is recovered in the feces after oral administration. The aim of the study was to determine to what extent the yeast was sensitive to gastrointestinal pH conditions. Therefore we explored the survival of different concentrations of S. boulardii in conditions mimicking the stomach pH (pH 1.1 0.1 N HCl) and the intestinal pH (pH 6.8 phosphate buffer) in vitro. The probiotic being commercialized as a freeze-dried powder obtained from an aqueous suspension, both forms were evaluated. In phosphate buffer pH 6.8, the viability remained stable for both forms of S. boulardii for 6 h. In HCl pH 1.1, viability of both forms (200 mg L(-1)) significantly decreased from 5 min. Observation under scanning/transmission electron microscopy showed morphological damages and rupture of the yeast wall. Threshold value from which S. boulardii viability was unaltered was pH 4. At the highest concentration of 200 g L(-1), the initial pH value of 1.1 rose to 3.2, exerting a protective effect. In conclusion, although the yeast in aqueous suspension was less sensitive than the freeze-dried yeast to acidic conditions, a gastric protection for improvement of oral bioavailability of viable S. boulardii appears necessary.     

Modifying action of Saccharomyces boulardii on the biological properties of enterobacteria

The influence of the exometabolites of the fungus S. boulardii, contained in the probiotic preparation "Enterol", on the biological properties of opportunistic and pathogenic enterobacteria of fecal microflora (inactivation of lysozyme, colicin production, hemolytic activity, antibiotic resistance) was studied. The study revealed that the supernatants of S. boulardii decreased antilysozyme activity (ALA) in lactose positive (lac+) and lactose negative (lac-) Escherichia coli and Klebsiella strains, but produced no influence on ALA in Salmonella. In response to the action of S. boulardii exometabolites colicin production in E. coli (lac+) was found to increase, while in E. coli (lac-) colicin production was suppressed. An increase in the sensitivity of lactose negative E. coli to cefazolin and cefotaxime under the action of S. boulardii supenatants was noted. The results obtained in this study show the probable mechanism of the corrective action of "Enterol" on intestinal biocenosis, which should be taken into consideration in the differentiated selection of probiotics for the treatment of intestinal dysbacteriosis.     

Microbial Succession in the Gut: Directional Trends of Taxonomic and Functional Change in a Birth Cohort of Spanish Infants

In spite of its major impact on life-long health, the process of microbial succession in the gut of infants remains poorly understood. Here, we analyze the patterns of taxonomic and functional change in the gut microbiota during the first year of life for a birth cohort of 13 infants. We detect that individual instances of gut colonization vary in the temporal dynamics of microbiota richness, diversity, and composition at both functional and taxonomic levels. Nevertheless, trends discernible in a majority of infants indicate that gut colonization occurs in two distinct phases of succession, separated by the introduction of solid foods to the diet. This change in resource availability causes a sharp decrease in the taxonomic richness of the microbiota due to the loss of rare taxa (p = 2.06e-9), although the number of core genera shared by all infants increases substantially. Moreover, although the gut microbial succession is not strictly deterministic, we detect an overarching directionality of change through time towards the taxonomic and functional composition of the maternal microbiota. Succession is however not complete by the one year mark, as significant differences remain between one-year-olds and their mothers in terms of taxonomic (p = 0.009) and functional (p = 0.004) microbiota composition, and in taxonomic richness (p = 2.76e-37) and diversity (p = 0.016). Our results also indicate that the taxonomic composition of the microbiota shapes its functional capacities. Therefore, the observed inter-individual variability in taxonomic composition during succession is not fully compensated by functional equivalence among bacterial genera and may have important physiological consequences. Finally, network analyses suggest that positive interactions among core genera during community assembly contribute to ensure their permanence within the gut, and highlight an expansion of complexity in the interactions network as the core of taxa shared by all infants grows following the introduction of solid foods.     

The Gut Microbial Community of Midas Cichlid Fish in Repeatedly Evolved Limnetic-Benthic Species Pairs

Gut bacterial communities are now known to influence a range of fitness related aspects of organisms. But how different the microbial community is in closely related species, and if these differences can be interpreted as adaptive is still unclear. In this study we compared microbial communities in two sets of closely related sympatric crater lake cichlid fish species pairs that show similar adaptations along the limnetic-benthic axis. The gut microbial community composition differs in the species pair inhabiting the older of two crater lakes. One major difference, relative to other fish, is that in these cichlids that live in hypersaline crater lakes, the microbial community is largely made up of Oceanospirillales (52.28%) which are halotolerant or halophilic bacteria. This analysis opens up further avenues to identify candidate symbiotic or co-evolved bacteria playing a role in adaptation to similar diets and life-styles or even have a role in speciation. Future functional and phylosymbiotic analyses might help to address these issues.     

Dietary Fat Content and Fiber Type Modulate Hind Gut Microbial Community and Metabolic Markers in the Pig

Obesity leads to changes in the gut microbial community which contribute to the metabolic dysregulation in obesity. Dietary fat and fiber affect the caloric density of foods. The impact of dietary fat content and fiber type on the microbial community in the hind gut is unknown. Effect of dietary fat level and fiber type on hindgut microbiota and volatile fatty acid (VFA) profiles was investigated. Expression of metabolic marker genes in the gut, adipose tissue and liver was determined. A 2×2 experiment was conducted in pigs fed at two dietary fat levels (5% or 17.5% swine grease) and two fiber types (4% inulin, fermentable fructo-oligosaccharide or 4% solka floc, non-fermentable cellulose). High fat diets (HFD) resulted in a higher (P<0.05) total body weight gain, feed efficiency and back fat accumulation than the low fat diet. Feeding of inulin, but not solka floc, attenuated (P<0.05) the HFD-induced higher body weight gain and fat mass accumulation. Inulin feeding tended to lead to higher total VFA production in the cecum and resulted in a higher (P<0.05) expression of acyl coA oxidase (ACO), a marker of peroxisomal β-oxidation. Inulin feeding also resulted in lower expression of sterol regulatory element binding protein 1c (SREBP-1c), a marker of lipid anabolism. Bacteria community structure characterized by DGGE analysis of PCR amplified 16S rRNA gene fragments showed that inulin feeding resulted in greater bacterial population richness than solka floc feeding. Cluster analysis of pairwise Dice similarity comparisons of the DGGE profiles showed grouping by fiber type but not the level of dietary fat. Canonical correspondence analysis (CCA) of PCR- DGGE profiles showed that inulin feeding negatively correlated with back fat thickness. This study suggests a strong interplay between dietary fat level and fiber type in determining susceptibility to obesity.     

Gene Expression Profiling in Preterm Infants: New Aspects of Bronchopulmonary Dysplasia Development

Rationale

Bronchopulmonary dysplasia is one of the most serious complications observed in premature infants. Thanks to microarray technique, expression of nearly all human genes can be reliably evaluated.

Objective

To compare whole genome expression in the first month of life in groups of infants with and without bronchopulmonary dysplasia.

Methods

111 newborns were included in the study. The mean birth weight was 1029g (SD:290), and the mean gestational age was 27.8 weeks (SD:2.5). Blood samples were drawn from the study participants on the 5th, 14th and 28th day of life. The mRNA samples were evaluated for gene expression with the use of GeneChip® Human Gene 1.0 ST microarrays. The infants were divided into two groups: bronchopulmonary dysplasia (n=68) and control (n=43).

Results

Overall 2086 genes were differentially expressed on the day 5, only 324 on the day 14 and 3498 on the day 28. Based on pathway enrichment analysis we found that the cell cycle pathway was up-regulated in the bronchopulmonary dysplasia group. The activation of this pathway does not seem to be related with the maturity of the infant. Four pathways related to inflammatory response were continuously on the 5^th, 14^th and 28^th day of life down-regulated in the bronchopulmonary dysplasia group. However, the expression of genes depended on both factors: immaturity and disease severity. The most significantly down-regulated pathway was the T cell receptor signaling pathway.

Conclusion

The results of the whole genome expression study revealed alteration of the expression of nearly 10% of the genome in bronchopulmonary dysplasia patients.     

Effect of Nutrient Periodicity on Microbial Community Dynamics

When microbes are subjected to temporal changes in nutrient availability, growth rate and substrate affinity can contribute to competitive fitness and thereby affect microbial community structure. This hypothesis was tested using planktonic bacterial communities exposed to nutrient additions at 1-, 3-, 7-, or 14-day intervals. Growth rates after nutrient addition were inversely proportional to the pulse interval and declined from 0.5 h⁻¹ to 0.15 h⁻¹ as the pulse interval increased from 1 to 14 days. The dynamics of community structure were monitored by 16S rRNA gene PCR-denaturing gradient gel electrophoresis. At pulse intervals of more than 1 day, the community composition continued to change over 130 days. Although replicate systems exposed to the same pulse interval were physiologically similar, their community compositions could exhibit as much dissimilarity (Dice similarity coefficients of <0.5) as did systems operated at different intervals. Bacteria were cultivated from the systems to determine if the physiological characteristics of individual members were consistent with the measured performance of the systems. The isolates fell into three bacterial divisions, Bacteroidetes, Proteobacteria, and Actinobacteria. In agreement with community results, bacteria isolated from systems pulsed every day with nutrients had higher growth rates and ectoaminopeptidase specific activities than isolates from systems pulsed every 14 days. However, the latter isolates did not survive starvation longer than those provided with nutrients every day. The present study demonstrates the dynamic nature of microbial communities exposed to even simple and regular environmental discontinuities when a substantial pool of species that can catabolize the limiting substrate is present.