Effects of Bifidobacterium lactis Bb12 supplementation on intestinal microbiota of preterm infants: a double-blind, placebo-controlled, randomized study

The gastrointestinal microbiota of preterm infants in a neonatal intensive care unit differs from that of term infants. In particular, the colonization of preterm infants by bifidobacteria is delayed. A double-blind, placebo-controlled, randomized clinical study was performed on 69 preterm infants to investigate the role of Bifidobacterium lactis Bb12 supplementation in modifying the gut microbiota. Both culture-dependent and culture-independent approaches were used to study the gut microbiota. Bifidobacterial numbers, determined by fluorescence in situ hybridization, were significantly higher in the probiotic than in the placebo group (log(10) values per g of fecal wet weight: probiotic, 8.18 + 0.54 [standard error of the mean]; placebo, 4.82 + 0.51; P < 0.001). A similar trend for bifidobacterial numbers was also obtained with the culture-dependent method. The infants supplemented with Bb12 also had lower viable counts of Enterobacteriaceae (log(10) values of CFU per g of fecal wet weight: probiotic, 7.80 + 0.34; placebo, 9.03 + 0.35; P = 0.015) and Clostridium spp. (probiotic, 4.89 + 0.30; placebo, 5.99 + 0.32; P = 0.014) than the infants in the placebo group. Supplementation of B. lactis Bb12 did not reduce the colonization by antibiotic-resistant organisms in the study population. However, the probiotic supplementation increased the cell counts of bifidobacteria and reduced the cell counts of enterobacteria and clostridia.     

早产儿喂养不耐受的胃肠内喂养方法研究

目的探讨改良微量胃肠内喂养法对喂养不耐受早产儿的临床效果。结论将符合纳入标准的喂养不耐受70例早产儿随机分为对照组和观察组,对照组采用常规微量胃肠道喂养法,观察组按照3h的间隔分别给予温开水、5%葡萄糖水和稀释奶（根据体重稀释）各喂养6次后,如无不耐受给予全奶喂养,比较两组患儿喂养不耐受各项观察指标的变化以及相关并发症的发病率。结果观察组患儿的黄疸持续时间、恢复出生体重时间、胃潴留消失时间、胎便排尽时间、平均出院时间分别为（14.6±2.5）d、（10.1±1.8）d、（5.1±1.2）d、（14.2±2.3）d、（19.2±2.3）d;对照组分别为（19.5±2.1）d、（13.5±1.3）d、（7.4±1.3）d、（18.7±2.5）d、（25.4±2.1）d,两组比较差异均有统计学意义（P〈0.001）。在吸吮出现时间和坏死性小肠结肠炎（NEC）、吸入性肺炎等并发症发病率方面,两组比较差异均无统计学意义（P〉0.05）。结论与常规微量胃肠道内喂养法相比,改良微量胃肠道内喂养法更能有效地缓解早产儿喂养不耐受症状。     

Interaction between intestinal microbiota and tumour immunity in the tumour microenvironment

In recent years, an increasing number of studies have reported that intestinal microbiota have an important effect on tumour immunity by affecting the tumour microenvironment (TME). The intestinal microbiota are closely associated with various immune cells, such as T lymphocytes, natural killer cells (NK cells) and macrophages. Some bacteria, such as Akkermansia muciniphila (A. muciniphila) and Lactobacillus reuteri (L. reuteri), have been shown to improve the effect of tumour immunity. Furthermore, microbial imbalance, such as the increased abundance of Fusobacterium nucleatum (F. nucleatum) and Helicobacter hepaticus (H. hepaticus), generally causes tumour formation and progression. In addition, some microbiota also play important roles in tumour immunotherapy, especially PD‐L1‐related therapies. Therefore, what is the relationship between these processes and how do they affect each other? In this review, we summarize the interactions and corresponding mechanisms among the intestinal microbiota, immune system and TME to facilitate the research and development of new targeted drugs and provide new approaches to tumour therapy.     

IgA and the intestinal microbiota: the importance of being specific

Secretory IgA has long been a divisive molecule. Some immunologists point to the mild phenotype of IgA deficiency to justify ignoring it, while some consider its abundance and evolutionary history as grounds for its importance. Further, there is extensive and growing disagreement over the relative importance of affinity-matured, T cell-dependent IgA vs. “natural” and T cell-independent IgA in both microbiota and infection control. As with all good arguments, there is good data supporting different opinions. Here we revisit longstanding questions in IgA biology. We start the discussion from the question of intestinal IgA antigen specificity and critical definitions regarding IgA induction, specificity, and function. These definitions must then be tessellated with the cellular and molecular pathways shaping IgA responses, and the mechanisms by which IgA functions. On this basis we propose how IgA may contribute to the establishment and maintenance of beneficial interactions with the microbiota.     

粪菌移植对严重烧伤大鼠肠道屏障功能的作用及相关机制

目的探讨粪菌移植(FMT)对严重烧伤大鼠肠道屏障功能的作用及相关机制。 方法按照随机数字表法将36只6～8周龄雄性SD大鼠分为3组：正常组(n＝12)、单纯烧伤组(n＝12)和FMT干预组(n＝12)。单纯烧伤组和FMT干预组大鼠制作30%总体表面积Ⅲ度烫伤模型;正常组大鼠不致伤。单纯烧伤组、FMT干预组大鼠伤后即刻腹腔注射平衡盐溶液40 mL/kg补液复苏。收集正常组大鼠新鲜粪便10 g,制成粪便滤液。伤后1 h,对FMT干预组大鼠进行粪便滤液灌胃(10 mL/kg),间隔12 h后再次给予相同剂量粪便滤液灌胃;正常组、单纯烧伤组大鼠在相同时相点均给予等量0.9%氯化钠溶液灌胃。分别于伤后24、72 h,取伤后各组大鼠结肠内新鲜粪便各1 mL,采用实时荧光定量-聚合酶链反应检测大鼠肠道菌群属水平,即双歧杆菌、脆弱拟杆菌、乳酸杆菌、大肠杆菌、肠球菌数量;取制备好的大鼠血浆,采用荧光素异硫氰酸酯(FITC)-葡聚糖通透性实验检测3组大鼠肠道通透性;采用酶联免疫吸附试验(ELISA)检测大鼠血清中二胺氧化酶、D-乳酸及白细胞介素(IL)-6、肿瘤坏死因子(TNF)-α、IL-10水平;分别取伤后24、72 h 3组大鼠的末端回肠组织约1 cm,苏木精-伊红染色观察大鼠肠黏膜组织形态结构。数据比较采用单因素方差分析和t检验。 结果(1)3组大鼠在伤后24、72 h双歧杆菌、脆弱拟杆菌、乳酸杆菌、大肠杆菌、肠球菌数量比较,差异均有统计学意义(P<0.05)。伤后24 h,单纯烧伤组大鼠肠道双歧杆菌、脆弱拟杆菌、乳酸杆菌、大肠杆菌、肠球菌数量分别为(2.76±0.15)、(3.27±0.40)、(2.33±0.33)、(7.06±0.49)、(6.42±0.50) LogN/g,FMT干预组大鼠分别为(3.18±0.16)、(4.52±0.58)、(2.92±0.28)、(6.14±0.47)、(5.28±0.43) LogN/g;伤后72 h,单纯烧伤组大鼠肠道双歧杆菌、脆弱拟杆菌、乳酸杆菌、大肠杆菌、肠球菌数量分别为(3.16±0.19)、(3.79±0.42)、(2.64±0.43)、(6.34±0.56)、(5.56±0.61) LogN/g,FMT干预组大鼠分别为(3.53±0.25)、(5.50±0.32)、(3.26±0.39)、(5.37±0.70)、(4.10±0.85) LogN/g,FMT干预组双歧杆菌、脆弱拟杆菌、乳酸杆菌数量均高于单纯烧伤组,大肠杆菌、肠球菌数量均低于单纯烧伤组,差异均有统计学意义(P<0.05)。(2)伤后24 h,正常组、单纯烧伤组和FMT干预组大鼠肠道通透性分别为0.94±0.16、2.39±0.37、1.58±0.33,伤后72 h,正常组、单纯烧伤组和FMT干预组大鼠肠道通透性分别为0.94±0.17、1.88±0.57、1.21±0.24,2个时相点3组间总体比较,差异均有统计学意义(F＝34.092、7.064,P<0.05);与单纯烧伤组比较,FMT干预组伤后24、72 h大鼠肠道通透性均降低,差异均有统计学意义(t＝ 3.971、2.664,P<0.05)。(3)伤后24、72 h,3组大鼠血清中二胺氧化酶、D-乳酸及IL-6、TNF-α、IL-10水平比较,差异均有统计学意义(P<0.05);伤后24 h,FMT干预组大鼠血清中二胺氧化酶、D-乳酸分别为(0.93±0.13) U/mL、(3.54±0.78) μmol/L,伤后72 h分别为(0.55±1.15)U/mL、(2.58±0.51)μmol/L,均明显低于单纯烧伤组伤后24 h[(1.28±0.18)U/mL、(4.83±0.57) μmol/L]、伤后72 h[(0.86±0.21)U/mL、(4.13±0.55)μmol/L],2组比较差异均有统计学意义(P<0.05)。伤后24、72 h,与单纯烧伤组比较,FMT干预组大鼠血清中IL-6、TNF-α水平均降低,IL-10水平均升高,差异均有统计学意义(P<0.05)。(4)伤后24、72 h,正常组大鼠肠黏膜上皮均完整,无炎症细胞浸润;伤后24 h,FMT干预组大鼠肠黏膜绒毛稍变短、排列略紊乱,散在上皮细胞破坏、黏膜脱落,有炎症细胞浸润,较单纯烧伤组相比较肠黏膜损伤减轻。伤后72 h,FMT干预组大鼠肠黏膜上皮基本完整,见少量炎症细胞浸润,肠黏膜修复较单纯烧伤组相比更为明显。 结论严重烧伤大鼠早期可出现肠道菌群紊乱、全身炎症反应加重、肠道屏障功能损害,FMT可以改善肠道菌群失调、抑制炎症反应,起到保护肠道屏障功能的作用。     

The effect of nonnutritive sucking on heart rate in preterm infants

A laboratory and a field experiment used within-subject designs to test the hypothesis that nonnutritive sucking (NNS) reduces heart rate (HR) in preterm infants. Infants in Experiment A were provided a standard pacifier nipple for 30 min under strictly controlled conditions. In the field Experiment B, nursing staff provided infants with a standard pacifier during alternate intervals in a sequence of four interfeed intervals spanning 12 hr. NNS significantly reduced average HR in each experiment. Given the strongly positive relationship between HR and energy expenditure, these results suggest that NNS reduces energy expenditure in preterm infants. Such an effect, in turn, could help to explain how the opportunity to engage in NNS enhances growth in preterms.     

Effects of mode of delivery and necrotising enterocolitis on the intestinal microflora in preterm infants

To investigate the effects of mode of delivery and of necrotising enterocolitis on the faecal microflora, 140 infants born before 33 weeks of gestation were followed up for symptoms of necrotising enterocolitis. Stool samples for gas–liquid chromatography and culture were collected twice weekly, and, when necrotising enterocolitis was suspected, for 2 months. For each infant with necrotising enterocolitis (n=21), two control infants matched for birth weight and gestational age were selected from the remaining study population. In gas–liquid chromatography analysis, the faecal bacterial microflora of infants born via caesarean section differed significantly from the gut microflora of those born via the vaginal route. The intestinal microflora showed a significant alteration in the necrotising enterocolitis group at time of diagnosis. At the onset of necrotising enterocolitis, faecal colonisation with Enterococcus species and Candida albicans was significantly more frequent in symptomatic infants than in controls. In infants with positive blood cultures and positive intestinal biopsy cultures, concomitant stool samples revealed the same microbial pathogens. In conclusion, the intestinal microbial colonisation in preterm infants born by caesarean section differs from that in preterm infants born via the vaginal route. A significant change in faecal microbial colonisation seems to occur at the onset of necrotising enterocolitis. Pathogens detected in the stools at that time might have a causative role in the development of the disease.     

The role of the intestinal microbiota in enteric infection

The consortia of microorganisms inhabiting the length of the gastrointestinal tract, the gastrointestinal microbiota, are vital to many aspects of normal host physiology. In addition, they are an active participant in the progression of many diseases, among them enteric infections. Healthy intestinal microbiota contribute to host resistance to infection through their involvement in the development of the host immune system and provision of colonization resistance. It is not surprising then that disruptions of the microbial community translate into alterations of host susceptibility to infection. Additionally, the process of the infection itself results in a disturbance to the microbiota. This disturbance is often mediated by the host inflammatory response, allowing the pathogen to benefit from the inflammation at the intestinal mucosa. Uncovering the mechanisms underlying the host–pathogen-microbiota interactions will facilitate our understanding of the infection process and promote design of more effective and focused prophylactic and therapeutic strategies.     

The role of the intestinal microbiota in type 1 diabetes

The digestive tract hosts trillions of bacteria that interact with the immune system and can influence the balance between pro-inflammatory and regulatory immune responses. Recent studies suggest that alterations in the composition of the intestinal microbiota may be linked with the development of type 1 diabetes (T1D). Data from the biobreeding diabetes prone (BBDP) and the LEW1.WR1 models of T1D support the hypothesis that intestinal bacteria may be involved in early disease mechanisms. The data indicate that cross-talk between the gut microbiota and the innate immune system may be involved in islet destruction. Whether a causal link between intestinal microbiota and T1D exists, the identity of the bacteria and the mechanism whereby they promote the disease remain to be examined. A better understanding of the interplay between microbes and innate immune pathways in early disease stages holds promise for the design of immune interventions and disease prevention in genetically susceptible individuals.     

Measurement of specific IgA in faecal extracts and intestinal lavage fluid for monitoring of mucosal immune responses

Currently available methods for the evaluation of antigen-specific immune responses in the intestine, i.e. measurement of IgA in intestinal lavage and antibody secreting cells (ASC) in peripheral blood, are not applicable to large-scale immunogenicity studies or to kinetic studies where repeated sampling is required. Simple and reliable methods need to be developed. Intestinal lavage and faecal samples were collected from 12 mice on days 0, 14, 21, 28 and 35 following initial immunization with four doses of cholera toxin (CT) by the gastric or rectal routes. The concentrations of anti-CT IgA in the faecal extracts showed a high level of correlation with those in the lavage samples (Spearman's correlation coefficient=0.85, P<0. 0001) regardless of the route of CT administration. Moreover, the kinetics of the immune response as reflected in the faecal extracts mirrored those in the lavage samples regardless of immunization route. As compared to gastric immunization, rectal administration of CT yielded higher levels of anti-CT IgA in both intestinal lavage fluids and in faecal extracts. The use of rectal immunization and the measurement of IgA in faecal extracts for monitoring mucosal immune responses may be relevant for the development of effective enteric vaccines.     

Molecular fingerprinting of the intestinal microbiota of infants in whom atopic eczema was or was not developing

BACKGROUND: The rise in atopic diseases has been linked to disturbances in the intestinal microbiota composition. OBJECTIVE: The purpose of this study was to investigate the intestinal microbiota composition in infants in whom atopic (IgE-associated) eczema was or was not developing, using a molecular fingerprinting technique. METHODS: Within a prospective birth cohort study, fecal samples have been collected at the infant's age of 1 month. Within the context of this cohort, we conducted a nested case-control study comparing fecal samples of 26 infants who became sensitized and developed eczema within the first year of life with 52 non-sensitized non-eczematous infants. The composition of the fecal samples was examined using PCR combined with denaturing gradient gel electrophoresis. Using real-time PCR, total bacterial counts and bifidobacterial counts were enumerated. RESULTS: Neither total bacterial profiles nor the type and proportion of bifidobacteria in the feces were associated with the development of atopic eczema. The similarity of bacterial profiles was low; mean similarity was approximately 33% in both infants with or without atopic eczema. The prevalence of one specific band in total bacterial profiles was significantly higher in infants with atopic eczema compared with controls (96% vs. 71%, P = 0.01). Identification of this band revealed that it represented Escherichia coli. CONCLUSION: Although no association was found between the development of IgE-associated eczema and the dominant gut microbiota as a whole or with the bifdobacterial microbiota, the association with E. coli indicates that differences in gut microbiota do precede the development of atopy.     

The role of the intestinal microbiota in the development of atopic disorders

The prevalence of atopic diseases, including eczema, allergic rhinoconjunctivitis and asthma, has increased worldwide, predominantly in westernized countries. Recent epidemiological studies and experimental research suggest that microbial stimulation of the immune system influences the development of tolerance to innocuous allergens. The gastrointestinal microbiota composition may be of particular interest, as it provides an early and major source of immune stimulation and seems to be a prerequisite for the development of oral tolerance. In this review the observational studies of the association between the gut microbiota and atopic diseases are discussed. Although most studies indicated an association between the gut microbiota composition and atopic sensitization or symptoms, no specific harmful or protective microbes can be identified yet. Some important methodological issues that have to be considered are the microbiological methods used (traditional culture vs molecular techniques), the timing of examining the gut microbiota, the definition of atopic outcomes, confounding and reverse causation. In conclusion, the microbiota hypothesis in atopic diseases is promising and deserves further attention. To gain more insight into the role of the gut microbiota in the etiology of atopy, large-scale prospective birth cohort studies using molecular methods to study the gut microbiota are needed.     

Maternal breast-milk and intestinal bifidobacteria guide the compositional development of the Bifidobacterium microbiota in infants at risk of allergic disease

Background The sources and the impact of maternal bacteria on the initial inoculum of the intestinal microflora of newborn infants remain elusive. Objective To assess the association between maternal breast‐milk and fecal bifidobacteria and infants' fecal bifidobacteria. Methods Sixty‐one mother–infant pairs were included, special emphasis being placed on the maternal allergic status. Bifidobacteria were analysed by a direct PCR method in fecal samples from mothers at 30–35 weeks of gestation and from infants at 1 month of age and from breast‐milk samples 1 month post‐partum. Results Fecal Bifidobacterium adolescentis and Bifidobacterium bifidum colonization frequencies and counts among mother–infant pairs correlated significantly (P=0.005 and 0.02 for frequencies, respectively, and P=0.002 and 0.01 for counts, respectively). Only infants of allergic, atopic mothers were colonized with B. adolescentis. Each of the breast‐milk samples contained bifidobacteria [median 1.4 × 10³ bacterial cells/mL; interquartile range (IQR) 48.7–3.8 × 10³]. Bifidobacterium longum was the most frequently detected species in breast‐milk. Allergic mothers had significantly lower amounts of bifidobacteria in breast‐milk compared with non‐allergic mothers [median 1.3 × 10³ bacterial cells/mL (IQR 22.4–3.0 × 10³) vs. 5.6 × 10³ bacterial cells/mL (1.8 × 10³–1.8 × 10⁴), respectively, (P=0.004)], and their infants had concurrently lower counts of bifidobacteria in feces [3.9 × 10⁸ bacterial cells/g (IQR 6.5 × 10⁶–1.5 × 10⁹) in infants of allergic mothers, vs. 2.5 × 10⁹ bacterial cells/g (6.5 × 10⁸–3.2 × 10¹⁰) in infants of non‐allergic mothers, P=0.013]. Conclusions Breast‐milk contains significant numbers of bifidobacteria and the maternal allergic status further deranges the counts of bifidobacteria in breast‐milk. Maternal fecal and breast‐milk bifidobacterial counts impacted on the infants' fecal Bifidobacterium levels. Breast‐milk bacteria should thus be considered an important source of bacteria in the establishment of infantile intestinal microbiota.     

Characterization of virus-like particles associated with the human faecal and caecal microbiota

This work represents an investigation into the presence, abundance and diversity of virus-like particles (VLPs) associated with human faecal and caecal samples. Various methodologies for the recovery of VLPs from faeces were tested and optimized, including successful down-stream processing of such samples for the purpose of an in-depth electron microscopic analysis, pulsed-field gel electrophoresis and efficient DNA recovery. The applicability of the developed VLP characterization method beyond the use of faecal samples was then verified using samples obtained from human caecal fluid.     

人乳与早产儿配方乳喂养对早产儿生长的Meta分析

目的对单纯人乳、强化人乳和早产儿配方乳喂养早产儿的生长进行评价。方法检索PubMed、ScienceDirect、EBSCOHost、EMBASE、OVID、Cochrane图书馆、维普中文科技期刊数据库和中国期刊全文数据库,并手工检索会议记录和专题论文集等,收集关于单纯人乳、强化人乳与早产儿配方乳喂养早产儿的RCT研究,进行文献筛选和质量评价,采用RevMan5.0.18软件进行Meta分析,计量资料采用加权均数差（WMD）及其95%CI表示。无法进行合并分析的资料进行描述性分析。结果共纳入7篇文献,文献质量评价5篇为B级,2篇为C级。Meta分析结果显示：①对近期生长的影响：单纯人乳喂养组新生儿期体重增加速度（WMD=-6.03,95%CI：-9.58～-2.47,P=0.0009）、身长增长速度（WMD=-1.96,95%CI：-2.77～-1.16,P〈0.00001）及头围增长速度（WMD=-2.04,95%CI：-3.71～-0.37,P=0.02）均显著慢于早产儿配方乳喂养组;强化人乳喂养组新生儿期体重、身长和头围的增长速度与早产儿配方乳喂养组差异均无统计学意义。②...更多对远期生长的影响：单纯人乳喂养组与早产儿配方乳喂养组随访至9和18个月,以及7.5～8岁时的体重、身长（高）和头围的差异均无统计学意义。结论现有证据提示,强化人乳喂养可促进早产儿生后近期内生长,单纯人乳和强化人乳对早产儿远期生长的影响仍需进一步研究。