Intestinal microbiota and immunoglobulin E responses in 5-year-old Estonian children

The potential immunomodulatory role of the gut microbiota in the pathogenesis of asthma: an in vitro study

The aim of this study was to investigate the influence of Bacteroides vulgatus (BV), Clostridium perfringens (CP), Parabacteroides distasonis (PD) and Ruminococcus albus (RA) lysates on secretion of selected cytokines by PBMC, MDM and HT-29 cells, as well as to determine the potential mechanisms of their action in the development of asthma. Enzyme-linked immunosorbent assays were used to analyze the effect of BV, CP, PD and RA lysates on the secretion of IL-1β, IL-6, IL-10 and TNF-α by human PBMC, MDM and HT-29 cells. BV and CP lysates significantly lowered IL-1β secretion by MDM vs. control (p < 0.05 and p < 0.001 respectively) but only at a dose of 400 µg lysate. The secretions of IL-6 by PBMC and MDM were elevated significantly above control values (p < 0.05) after administration of CP and PD lysates. BV, CP and PD lysates (100 µg) significantly increased IL-10 secretion by PBMC vs. control (p < 0.05). CP, PD and RA lysates (400 µg) significantly increased IL-10 secretion by MDM vs. control (p < 0.001). BV lysate (400 µg) also significantly increased IL-10 secretion by MDM as compared to control (p < 0.05). In PBMC and MDM, the production levels of the anti-inflammatory cytokine were increased by all the bacterial lysates used in a dose-dependent manner.

Impact of a phage cocktail targeting Escherichia coli and Enterococcus faecalis as members of a gut bacterial consortium in vitro and in vivo

Escherichia coli and Enterococcus faecalis have been implicated as important players in human gut health that have been associated with the onset of inflammatory bowel disease (IBD). Bacteriophage (phage) therapy has been used for decades to target pathogens as an alternative to antibiotics, but the ability of phage to shape complex bacterial consortia in the lower gastrointestinal tract is not clearly understood. We administered a cocktail of six phages (either viable or heat-inactivated) targeting pro-inflammatory Escherichia coli LF82 and Enterococcus faecalis OG1RF as members of a defined community in both a continuous fermenter and a murine colitis model. The two target strains were members of a six species simplified human microbiome consortium (SIHUMI-6). In a 72-h continuous fermentation, the phage cocktail caused a 1.1 and 1.5 log (log10 genome copies/mL) reduction in E. faecalis and E. coli numbers, respectively. This interaction was accompanied by changes in the numbers of other SIHUMI-6 members, with an increase of Lactiplantibacillus plantarum (1.7 log) and Faecalibacterium prausnitzii (1.8 log). However, in germ-free mice colonized by the same bacterial consortium, the same phage cocktail administered twice a week over nine weeks did not cause a significant reduction of the target strains. Mice treated with active or inactive phage had similar levels of pro-inflammatory cytokines (IFN-y/IL12p40) in unstimulated colorectal colonic strip cultures. However, histology scores of the murine lower GIT (cecum and distal colon) were lower in the viable phage-treated mice, suggesting that the phage cocktail did influence the functionality of the SIHUMI-6 consortium. For this study, we conclude that the observed potential of phages to reduce host populations in in vitro models did not translate to a similar outcome in an in vivo setting, with this effect likely brought about by the reduction of phage numbers during transit of the mouse GIT.

Mechanisms Underlying the Skin-Gut Cross Talk in the Development of IgE-Mediated Food Allergy

Immune-globulin E (IgE)-mediated food allergy is characterized by a variety of clinical entities within the gastrointestinal tract, skin and lungs, and systemically as anaphylaxis. The default response to food antigens, which is antigen specific immune tolerance, requires exposure to the antigen and is already initiated during pregnancy. After birth, tolerance is mostly acquired in the gut after oral ingestion of dietary proteins, whilst exposure to these same proteins via the skin, especially when it is inflamed and has a disrupted barrier, can lead to allergic sensitization. The crosstalk between the skin and the gut, which is involved in the induction of food allergy, is still incompletely understood. In this review, we will focus on mechanisms underlying allergic sensitization (to food antigens) via the skin, leading to gastrointestinal inflammation, and the development of IgE-mediated food allergy. Better understanding of these processes will eventually help to develop new preventive and therapeutic strategies in children.

Diagnostic Models for Atopic Dermatitis Based on Serum Microbial Extracellular Vesicle Metagenomic Analysis: A Pilot Study

PURPOSE

Associations between a wide variety of diseases and the microbiome have been extensively verified. Recently, there has been a rising interest in the role the microbiome plays in atopic dermatitis (AD). Furthermore, metagenomic analysis of microbe-derived extracellular vesicles (EVs) has revealed the importance and relevance of microbial EVs in human health.

METHODS

We compared the diversity and proportion of microbial EVs in the sera of 24 AD patients and 49 healthy controls, and developed a diagnostic model. After separating microbial EVs from serum, we specifically targeted the V3-V4 hypervariable regions of the 16S rDNA gene for amplification and subsequent sequencing.

RESULTS

Alpha and beta diversity between controls and AD patients both differed, but only the difference in beta diversity was significant. Proteobacteria, Firmicutes, and Bacteroidetes were the dominant phyla in healthy controls and AD patients, accounting for over 85% of the total serum bacterial EVs. Also, Proteobacteria, Firmicutes, Actinobacteria, Verrucomicrobia, and Cyanobacteria relative abundances were significantly different between the AD and control groups. At the genus level, the proportions of Escherichia-Shigella, Acinetobacter, Pseudomonas, and Enterococcus were drastically altered between the AD and control groups. AD diagnostic models developed using biomarkers selected on the basis of linear discriminant analysis effect size from the class to genus levels all yielded area under the receiver operating characteristic curve, sensitivity, specificity, and accuracy of value 1.00.

CONCLUSIONS

In summary, microbial EVs demonstrated the potential in their use as novel biomarkers for AD diagnosis. Therefore, future work should investigate larger case and control groups with cross-sectional or longitudinal clinical data to explore the utility and validity of serum microbiota EV-based AD diagnosis.

Gut microbiota of children with atopic dermatitis: Controlled study in the metropolitan region of São Paulo, Brazil

BACKGROUND

It is possible that imbalances in the composition of the gut microbiota or the relationship of the microbiota with the host may be implicated in the origin of allergy. Therefore, we studied the intestinal microbiota of children with atopic dermatitis (AD).

METHODS

Cross-sectional study with 81 children aged 5-11; 23 with AD and 58 controls. Surveys were conducted to obtain demographic, socioeconomic and neonatal data. Diagnosis of AD was made based on the International Study of Asthma and Allergies in Childhood (ISAAC) questionnaire. Eubacteria, Bacteroidetes, Firmicutes, B. fragilis, E. coli, Lactobacillus spp., S. aureus, E. faecalis, Salmonella spp., M. smithii, Bifidobacterium spp., C. difficile and C. perfringens were quantified using real-time PCR.

RESULTS

The analysis showed an association between presence of C. difficile (OR: 5.88; 95 % CI: 1.24; 27.98), greater abundance of bifidobacteria (OR: 11.09; 95 % CI: 2.14; 57.39) and a lower abundance of lactobacilli (OR: 0.07; 95 % CI: 0.01; 0.51) in the gut microbiota of children with AD. Counts of Eubacteria (0,05×10³ and 8.49×10³), B. fragilis (0.72×10⁹ and 4.5×10⁹), Lactobacillus spp. (0.02×10⁸ and 0.38×10⁸), E. coli (0.13×10⁹ and 1.52×10⁹) and M. smithii (0.02×10⁸ and 0.31×10⁸) were lower in children with AD (P<0.05).

CONCLUSIONS

This study confirmed that children living in the metropolitan area of São Paulo (Brazil) with AD have a different microbiota pattern with higher prevalence of C. difficile, lower abundance of Lactobacillus and greater abundance of bifidobacteria, regardless of socioeconomic status.

Antibiotic exposure and asthma development in children with allergic rhinitis

PURPOSE

Early-life antibiotic use may be associated with asthma, yet whether this association also exists in patients with allergic rhinitis (AR) remains unknown. We investigated the association between antibiotic exposure and asthma development in AR children.

METHODS

AR patients less than 18 year-old were enrolled from the Taiwan National Health Insurance Database, which reported information from 2005 to 2010. The case group was defined as having newly developed asthma, and the control group was defined as never having an asthma diagnosis. The age of first exposure to antibiotic prescriptions and antibiotic exposure records preceding 5 years before the first asthma diagnosis were obtained from drug prescription records. The odds ratio (OR) was examined after adjusting for age, gender, resident urbanization, underlying medical disorders and medications.

RESULTS

A total of 3236 AR patients with newly developed asthma and 9708 AR patients without asthma were included in this study. Antibiotic exposure before the age of 3 years was not associated with asthma development. Preceding 5-year antibiotic exposure increased the risk of asthma development with a dose-response relationship, even for antibiotics with low cumulative defined daily doses (adjusted OR 1.40, 95% CI 1.12-1.75). Preceding 5-year exposure to penicillin and macrolide significantly increased the risk of asthma when diagnosed before age 12 in AR patients, but this was not statistically significant when asthma diagnosed after age 12.

CONCLUSION

Preceding 5-year antibiotic exposure, particularly to penicillin group of amoxicillin and macrolides, is associated with the risk of asthma development before age 12 in AR children.

Neonatal microbiome - a brief review

The long-held concept of fetus being nurtured in a sterile environment has been challenged by many recent studies that have identified bacterial communities in meconium, amniotic fluid and the placenta concluding that the microbial colonization of fetal gut begins in utero and continues during the first 2 years of life. This microbial colonization of newborn's gut during prenatal, intrapartum, and postnatal period depends on multiple factors, e.g. maternal diet, stress, antibiotic exposure, mode of delivery, type of feeding (human milk versus formula), etc., and imparts a critical role in the development of gastrointestinal, immunological, and neural systems in newborns. This article briefly reviews the current state of knowledge of microbiome in the maternal fetal unit and its impact on subsequent neonatal health and diseases.

The gut microbiome in food allergy

OBJECTIVE

To review observational human, murine, and interventional trial studies that have examined the gut microbiome in food allergy, and to provide perspective on future investigations in this field.

DATA SOURCES

A review of the published literature was performed with PubMed, and clinical studies catalogued at ClinicalTrials.gov were also reviewed.

STUDY SELECTIONS

The most recent relevant studies, seminal works, and topical clinical trials were selected.

RESULTS

Gut dysbiosis likely precedes the development of food allergy, and the timing of such dysbiosis is critical. Gut microbiota associated with individual food allergies may be distinct. Murine models support the importance of gut microbiota in shaping immune maturation and tolerance. Gut microbiota may affect food allergy susceptibility by modulating type 2 immunity, influencing immune development and tolerance, regulating basophil populations, and promoting intestinal barrier function. Ongoing and future interventional trials of probiotics, prebiotics, synbiotics, and fecal microbiota transfer will help translate our understanding of the gut microbiome in food allergy to clinical practice. Future work in this area will include deepening of current research foci, as well as expansion of efforts to include the virome, mycobiome, and interactions between the microbiome, host, and environment. Robust and consistent study designs, multidimensional profiling, and systems biology approaches will enable this future work.

CONCLUSION

By advancing research on the microbiome in food allergy, we can further our understanding of food allergy and derive new approaches for its prevention and therapy.

Association between the intestinal microbiota and allergic sensitization, eczema, and asthma: A systematic review

The intestinal microbiota plays an important role in development of the immune system and regulation of immune responses. This review summarizes the association between the intestinal microbiota and the development of allergic sensitization, eczema, and asthma in neonates and children. Overall, a greater relative abundance of Bacteroidaceae, Clostridiaceae, and Enterobacteriaceae and a lower relative abundance of Bifidobacteriaceae and Lactobacillaceae is associated with the development of allergic sensitization, eczema, or asthma. Reduced bacterial diversity can be associated with the development of allergic disease. The association between the composition of the intestinal microbiota and the development of allergic disease or asthma is less consistent in older children than in neonates, suggesting that early-life microbial exposure plays a more important role. Inconsistencies in the results reported from different studies might partly be explained by heterogeneity in design, study populations, diagnostic criteria, microbiota analysis methods, and reporting on different taxonomic levels. Larger studies that better account for antenatal and postnatal factors will further help determine specific microbial intestinal signatures associated with increased risk of allergy and asthma. This will enable the early identification of infants at high risk and facilitate novel strategies and interventions to prevent and treat these conditions, including modifying the intestinal microbiota early in life.

Air Pollution, Early Life Microbiome, and Development

PURPOSE OF REVIEW

We review how an altered microbiome in early life impacts on immune, metabolic, and neurological development, focusing on some of the most widespread diseases related to each of these processes, namely atopic disease, obesity, and autism.

RECENT FINDINGS

The early development of the microbial communities that inhabit the human body is currently challenged by factors that range from reduced exposure to microbes, antibiotic use, and poor dietary choices to widespread environmental pollution. Recent work has highlighted some of the long-term consequences that early alterations in the establishment of these microbiotas can have for different aspects of human development and health. The long-term consequences of early microbiome alterations for human development and health are only beginning to be understood and will require in-depth investigation in the years to come. A solid understanding of how present day environmental conditions alter microbiome development, and of how an altered microbiome in early life impacts on life-long health, should inform both public health policies and the development of dietary and medical strategies to counteract early microbiota imbalances.

Microbial balance in the intestinal microbiota and its association with diabetes, obesity and allergic disease

Recent studies have been considered to symbiotic interactions of the human gastrointestinal microbiota and human lifestyle-related disorders. The human gastrointestinal microbiota continuously stimulates the immune system against opportunistic and pathogen bacteria from infancy. Changes in gastrointestinal microbiota have been associated with numbers of human diseases such as allergic diseases, autoimmune encephalitis, atherosclerosis, colorectal cancer, obesity, diabetes etc. In this review article, we evaluate studies on the roles of human gastrointestinal microbiota and interference pathogenicity in allergic diseases, obesity, and diabetes. Several studies indicated association between allergic diseases and changes in bacterial balance such as increased of Clostridium spp., some species of Bifidobacterium spp., or decreased of Bacteroidetes phylum and some species of Bifiobacterium spp. and production of specific short-chain fatty acids due to food type, delivery modes of infant, infant evolvement environment and time of getting bacteria at an early-life age. In addition, obesity and diabetes are associated with food type, production of short chain fatty acids undergo fermentation of the intestinal microbiota, metabolic endotoxemia, endocannabinoid system and properties of the immune system. Well-characterized underlying mechanisms may provide novel strategies for using prebiotic and probiotic to prevent and treatment of allergic diseases, obesity, diabetes, and other lifestyle-related disorders.

Sensitivity to oxazolone induced dermatitis is transferable with gut microbiota in mice

Atopic Dermatitis (AD) has been associated with gut microbiota (GM) dysbiosis in humans, indicating a causative role of GM in AD etiology. Furthermore, the GM strongly correlates to essential disease parameters in the well-known oxazolone-induced mouse model of AD. Here, we demonstrate that it is possible to transfer both a high-responding and a low-responding AD phenotype with GM from conventional mice to germ-free mice. The mice inoculated with the high-responding GM had significantly higher clinical score, increased ear thickness, and increased levels of IL-1β, TNFα, IL-4, IL-5, and IL-6 compared to the mice inoculated with the low-responding GM. The inter-individual variation was in general not affected by this increase in effect size. Germ-free mice induced with AD revealed a high disease response as well as high inter-individual variation indicating protective properties of certain microbial taxa in this model. This study underlines that the GM has a strong impact on AD in mouse models, and that the power of studies may be increased by the application of mice inoculated with a specific GM from high responders to increase the effect size.

The gut-skin axis in health and disease: A paradigm with therapeutic implications

As crucial interface organs gut and skin have much in common. Therefore it is unsurprising that several gut pathologies have skin co-morbidities. Nevertheless, the reason for this remains ill explored, and neither mainstream gastroenterology nor dermatology research have systematically investigated the 'gut-skin axis'. Here, in reviewing the field, we propose several mechanistic levels on which gut and skin may interact under physiological and pathological circumstances. We focus on the gut microbiota, with its huge metabolic capacity, and the role of dietary components as potential principle actors along the gut-skin axis. We suggest that metabolites from either the diet or the microbiota are skin accessible. After defining open key questions around the nature of these metabolites, how they are sensed, and which cutaneous changes they can induce, we propose that understanding of these pathways will lead to novel therapeutic strategies based on targeting one organ to improve the health of the other.

Lactobacillus rhamnosus GG Intake Modifies Preschool Children's Intestinal Microbiota, Alleviates Penicillin-Associated Changes, and Reduces Antibiotic Use

Antibiotic use is considered among the most severe causes of disturbance to children’s developing intestinal microbiota, and frequently causes adverse gastrointestinal effects ranging from mild and transient diarrhoea to life-threatening infections. Probiotics are commonly advocated to help in preventing antibiotic-associated gastrointestinal symptoms. However, it is currently unknown whether probiotics alleviate the antibiotic-associated changes in children’s microbiota. Furthermore, it is not known how long-term probiotic consumption influences the developing microbiota of children. We analysed the influence of long-term Lactobacillus rhamnosus GG intake on preschool children’s antibiotic use, and antibiotic-associated gastrointestinal complaints in a double blind, randomized placebo-controlled trial with 231 children aged 2–7. In addition, we analysed the effect of L. rhanmosus GG on the intestinal microbiota in a subset of 88 children. The results show that long-term L. rhamnosus GG supplementation has an influence on the composition of the intestinal microbiota in children, causing an increase in the abundance of Prevotella, Lactococcus, and Ruminococcus, and a decrease in Escherichia. The treatment appeared to prevent some of the changes in the microbiota associated with penicillin use, but not those associated with macrolide use. The treatment, however, did reduce the frequency of gastrointestinal complaints after a macrolide course. Finally, the treatment appeared to prevent certain bacterial infections for up to 3 years after the trial, as indicated by reduced antibiotic use.

Trial Registration: ClinicalTrials.gov NCT01014676

Neonatal Gastrointestinal and Respiratory Microbiome in Cystic Fibrosis: Potential Interactions and Implications for Systemic Health

PURPOSE

The gastrointestinal microbiome plays a critical role in nutrition and metabolic and immune functions in infants and young children and has implications for lifelong health. Cystic fibrosis (CF) transmembrane conductance regulator (CFTR) mutations in CF result in viscous mucous production, frequent exposure to antibiotics, and atypical colonization patterns, resulting in an evolving dysbiosis of the gastrointestinal and respiratory microsystems; dysbiosis in CF results in systemic inflammation, chronic infection, and dysregulation of immune function. Dysbiosis in both the respiratory system and gut contributes to undernutrition, growth failure, and long-term respiratory and systemic morbidity in infants and children with CF. Understanding the role that the gut and respiratory microbiome plays in health or disease progression in CF will afford opportunities to better identify interventions to affect clinical changes.

METHODS

Summary was done of the pertinent literature in CF and the study of the microbiome and probiotics.

FINDINGS

New studies have identified bacteria in the respiratory tract in CF that are typically members of the intestinal microbiota, and enteral exposures to breast milk and probiotics are associated with prolonged periods of respiratory stability in CF.

IMPLICATIONS

Understanding the complex interactions between the CFTR mutations, microbial colonization, and mucosal and systemic immunity is of major importance to inform new treatment strategies (such as restoring a healthier microbiome with probiotics or dietary interventions) to improve nutritional status and immune competence and to decrease morbidity and mortality in CF.

Intestinal microbiome is related to lifetime antibiotic use in Finnish pre-school children

Early-life antibiotic use is associated with increased risk for metabolic and immunological diseases, and mouse studies indicate a causal role of the disrupted microbiome. However, little is known about the impacts of antibiotics on the developing microbiome of children. Here we use phylogenetics, metagenomics and individual antibiotic purchase records to show that macrolide use in 2–7 year-old Finnish children (N=142; sampled at two time points) is associated with a long-lasting shift in microbiota composition and metabolism. The shift includes depletion of Actinobacteria, increase in Bacteroidetes and Proteobacteria, decrease in bile-salt hydrolase and increase in macrolide resistance. Furthermore, macrolide use in early life is associated with increased risk of asthma and predisposes to antibiotic-associated weight gain. Overweight and asthmatic children have distinct microbiota compositions. Penicillins leave a weaker mark on the microbiota than macrolides. Our results support the idea that, without compromising clinical practice, the impact on the intestinal microbiota should be considered when prescribing antibiotics.

The impact of antibiotics on the microbiome and health of children is poorly understood. Here, Korpela et al. study the gut microbiome of 142 children and show that the use of macrolides, but not penicillins, is associated with long-lasting shifts in microbiota composition and increased risk of asthma and overweight.

Antibiotics and the Human Gut Microbiome: Dysbioses and Accumulation of Resistances

The human microbiome is overly exposed to antibiotics, due, not only to their medical use, but also to their utilization in farm animals and crops. Microbiome composition can be rapidly altered by exposure to antibiotics, with potential immediate effects on health, for instance through the selection of resistant opportunistic pathogens that can cause acute disease. Microbiome alterations induced by antibiotics can also indirectly affect health in the long-term. The mutualistic microbes in the human body interact with many physiological processes, and participate in the regulation of immune and metabolic homeostasis. Therefore, antibiotic exposure can alter many basic physiological equilibria, promoting long-term disease. In addition, excessive antibiotic use fosters bacterial resistance, and the overly exposed human microbiome has become a significant reservoir of resistance genes, contributing to the increasing difficulty in controlling bacterial infections. Here, the complex relationships between antibiotics and the human microbiome are reviewed, with focus on the intestinal microbiota, addressing (1) the effects of antibiotic use on the composition and function of the gut microbiota, (2) the impact of antibiotic-induced microbiota alterations on immunity, metabolism, and health, and (3) the role of the gut microbiota as a reservoir of antibiotic resistances.

Turning the inside out: the microbiology of atopic dermatitis

Allergy is on the rise worldwide. The hygiene hypothesis of atopic diseases linked microbes with atopic dermatitis (AD) both as drivers and modulators of skin pathology. The earlier literature favoured an inside-outside model of AD where an immunological abnormality compounded by a gut microbiota dysbiosis is the primary event. Probiotic intervention trials with lactobacilli and bifidobacteria as well as the application of bifidogenic oligosaccharide prebiotics showed indeed promising clinical results, but no consistent gut microbiota dysbiosis could be linked with AD. An alternative hypothesis known as outside-inside model of AD considers a genetic skin barrier effect compounded by a skin microbiota dysbiosis as primary pathogenic event. Cultivation microbiology has demonstrated strong skin colonization with superantigen-encoding Staphylococcus aureus in AD patients; microbiota and molecular microbiome analyses demonstrated that S. aureus abundance fluctuates and parallels clinical symptoms. In a mouse model, δ-toxin of S. aureus induced mast cell degranulation, leading to AD-like symptoms. Mutant mice developing AD symptoms showed increased skin colonization with S. aureus; antibiotic treatment alleviated the symptoms. Clinical trials showed that various treatments reducing S. aureus skin load also reduced AD symptoms, suggesting S. aureus as a potential critical driver of AD and a target for antimicrobial interventions other than antibiotics.

Scientific evidence for health effects attributed to the consumption of probiotics and prebiotics: an update for current perspectives and future challenges

Probiotics and prebiotics, mainly commercialised as food ingredients and also as supplements, are considered highly profitable niche markets. However, in recent years, the food industry has suffered from a series of health claim restrictions on probiotics and prebiotics in many parts of the world, including those made by the European Food Safety Authority. Therefore, we reviewed the core benefits of probiotic and prebiotic consumption on health. A number of studies have examined the prevention and/or management of intestinal infections, respiratory tract infections, CVD, osteoporosis, urogenital infections, cavities, periodontal disease and halitosis, allergic reactions, inflammatory bowel disease and irritable bowel syndrome and Helicobacter pylori gastric infections. In fact, a deeper understanding of the mechanisms involved in human microbiota and immune system modulation by probiotics and prebiotics relies on continuous efforts to establish suitable biomarkers of health and diseases risk factors for the design of clinical trials required for health claim approval. In spite of the promising results, the performance of large, long-term, well-planned, well-aligned clinical studies is crucial to provide more reliability and a more solid basis for the outcomes achieved and to support the potential use of probiotics and prebiotics in clinical practice.

Mouthguards: does the indigenous microbiome play a role in maintaining oral health?

The existence of symbiotic relationships between bacteria and their hosts in various ecosystems have long been known to science. The human body also hosts vast numbers of bacteria in several habitats. Emerging evidence from the gastro-intestinal tract, genito-urinary tract and respiratory indicates that there are several health benefits to hosting a complex and diverse microbial community. Bacteria colonize the oral cavity within a few minutes after birth and form stable communities. Our knowledge of the oral microbiome has expanded exponentially with development of novel exploratory methods that allow us to examine diversity, structure, function, and topography without the need to cultivate the individual components of the biofilm. The purpose of this perspective, therefore, is to examine the strength of current evidence supporting a role for the oral microbiome in maintaining oral health. While several lines of evidence are emerging to suggest that indigenous oral microbiota may have a role in immune education and preventing pathogen expansion, much more work is needed to definitively establish whether oral bacteria do indeed contribute to sustaining oral health, and if so, the mechanisms underlying this role.

Amelioration of ovalbumin induced allergic symptoms in Balb/c mice by potentially probiotic strains of lactobacilli

To evaluate the antiallergic effect of newly characterised probiotic strains, Lactobacillus fermentum NWS29, Lactobacillus casei NWP08 and Lactobacillus rhamnosus NWP13, mice were divided into six experimental groups: control, ovalbumin (OVA), NWS29, NWP08, NWP13 and L. rhamnosus GG (LGG). Mice were immunised and probiotics were administered via oral gavage followed by challenge with OVA. After last challenge with OVA, inflammatory cells in bronchoalveolar lavage fluid (BALF), recruitment of inflammatory cells in airways and OVA-specific immunoglobulin E (IgE) in serum were determined by Giemsa, haematoxylin and eosin (HE) staining, and ELISA, respectively. Relative mRNA expression of interleukins (IL-4, IL-5, IL-10, IL-13 and IL-17), transforming growth factor-β (TGF-β) and interferon-γ (IFN-γ) in lung and spleen tissue was determined by real time RT-PCR. OVA-specific IgE levels, recruitment of eosinophils and mRNA expressions of inflammatory cytokines were remarkably increased in OVA-exposed mice compared with the control group. Administration of NWS29 and NWP13 suppressed inflammatory cell infiltration in airways and BALF, and level of OVA-specific IgE in serum of OVA-exposed mice. Furthermore, NWS29 and NWP13 also abrogated the mRNA expression of 1L-4, IL-5, IL-13 and TGF-β in mice immunised and exposed to OVA. Our findings suggest that NWS29 and NWP13 might be good candidates for the prevention of allergic airway inflammation.

Effects of bifidobacterial supplementation to pregnant women and infants in the prevention of allergy development in infants and on fecal microbiota

BACKGROUND

Probiotic administration may be a useful method for preventing allergies in infants; however, there have been controversial results about the efficacy. We investigated the effects of bifidobacterial supplementation on the risk of developing allergic diseases in the Japanese population.

METHODS

In an open trial, we gave Bifidobacterium breve M-16V and Bifidobacterium longum BB536 prenatally to 130 mothers beginning 1 month prior to delivery and postnatally to their infants for 6 months. Another 36 mother-infant pairs served as controls and did not receive the bifidobacterial supplementation. Development of allergic symptoms in the infants was assessed at 4, 10 and 18 months of age. Fecal samples were collected from the mothers and infants.

RESULTS

The risk of developing eczema/atopic dermatitis (AD) during the first 18 months of life was significantly reduced in infants in the probiotic group (OR: 0.231 [95% CI: 0.084-0.628] and 0.304 [0.105-0.892] at 10 and 18 months of age, respectively). Pyrosequencing analyses indicated an altered composition of the fecal microbiota at 4 months for infants who developed eczema/AD at 4 and 10 months of age. The proportion of Proteobacteria was significantly lower (P = 0.007) in mothers at the time of delivery who received the supplementation when compared with the control group and was positively correlated (r = 0.283, P = 0.024) with that of infants at 4 months of age. No adverse effects were related to the use of probiotics.

CONCLUSIONS

These data suggest that the prenatal and postnatal supplementation of bifidobacteria is effective in primary preventing allergic diseases. Some limited changes in the composition of fecal microbiota by the bifidobacterial supplementation were observed.

Prebiotics and probiotics: the prevention and reduction in severity of atopic dermatitis in children

The purpose of this review was to identify whether supplementation with prebiotics and/or probiotics help prevent the development or reduce the severity of atopic dermatitis in children less than three years of age. Since 1997, immunostimulatory supplements, such as prebiotics and probiotics, have been investigated. Various supplementations include probiotics (single strain or mix), probiotics with formula, probiotics mix with prebiotics, and prebiotics. In this narrative review, we examined 13 key articles on prebiotics and/or probiotics, and their effects on infant atopic dermatitis. Among the selected studies, a total of 3,023 participants received supplements or placebo. Eight out of the 13 (61.5%) studies reported a significant effect on the prevention of atopic dermatitis after supplementation with probiotics and/or prebiotics. Five out of the 13 (38.5%) studies indicated significant reduction in the severity of atopic dermatitis after supplementation. Based on the available studies, supplementation with certain probiotics (Lactobacillus rhamnosus GG) appears to be an effective approach for the prevention and reduction in severity of atopic dermatitis. A mix of specific probiotic strains prevented atopic dermatitis among infants. Based on studies with prebiotics, there was a long-term reduction in the incidence of atopic dermatitis. Supplementation with prebiotics and probiotics appears useful for the reduction in the severity of atopic dermatitis. Additional interventional studies exploring prebiotics and probiotics are imperative before recommendations can be made.

Early development of the gut microbiota and immune health

In recent years, the increase in human microbiome research brought about by the rapidly evolving “omic” technologies has established that the balance among the microbial groups present in the human gut, and their multipronged interactions with the host, are crucial for health. On the other hand, epidemiological and experimental support has also grown for the ‘early programming hypothesis’, according to which factors that act in utero and early in life program the risks for adverse health outcomes later on. The microbiota of the gut develops during infancy, in close interaction with immune development, and with extensive variability across individuals. It follows that the specific process of gut colonization and the microbe-host interactions established in an individual during this period have the potential to represent main determinants of life-long propensity to immune disease. Although much remains to be learnt on the progression of events by which the gut microbiota becomes established and initiates its intimate relationships with the host, and on the long-term repercussions of this process, recent works have advanced significatively in this direction.

Intestinal microbiota during early life - impact on health and disease

In the first years after birth, the intestinal microbiota develops rapidly both in diversity and complexity while being relatively stable in healthy adults. Different life-style-related factors as well as medical practices have an influence on the early-life intestinal colonisation. We address the impact of some of these factors on the consecutive microbiota development and later health. An overview is presented of the microbial colonisation steps and the role of the host in that process. Moreover, new early biomarkers are discussed with examples that include the association of microbiota and atopic diseases, the correlation of colic and early development and the impact of the use of antibiotics in early life. Our understanding of the development and function of the intestinal microbiota is constantly improving but the long-term influence of early-life microbiota on later life health deserves careful clinical studies.

Higher blood glucose level associated with body mass index and gut microbiota in elderly people

Background

Some dominant bacterial divisions of the intestines have been linked to metabolic diseases such as overweight and diabetes.

Objective

A pilot study aimed to evaluate the relations between the culturable intestinal bacteria with body mass index (BMI) and some principal cellular and metabolic markers of blood in people older than 65.

Design

Altogether 38 generally healthy elderly people were recruited: ambulatory (n=19) and orthopedic surgery (n=19). Questionnaires on general health, anthropometric measurements, routine clinical and laboratory data, and quantitative composition of cultivable gut microbiota were performed.

Results

Blood glucose level was positively correlated with BMI (r=0.402; p=0.014). Higher blood glucose level had negative correlation with relative share of intestinal anaerobic bacteria such as bacteroides (r=−0.434; p=0.0076) and gram-positive anaerobic cocci (r=−0.364; p=0.027). In contrast, the relative share of bifidobacteria (r=0.383; p=0.019) and staphylococci (r=0.433; p=0.008) was positively correlated to blood glucose level. In elderly people, a higher blood glucose concentration was predicted by the reduction of the anaerobes’ proportion (adj. sex, age, and BMI R²=0.192, p=0.028) and that of Bacteroides sp. (adj. R²=0.309, p=0.016).

Conclusion

A tight interplay between increased BMI, level of blood glucose, and the reduced proportion of cultivable bacteroides is taking place in the gut microbiota of elderly people.

The immunomodulatory effect of probiotics beyond atopy: an update

BACKGROUND

In the past decades, the theory of "allergen avoidance" was considered the standard treatment for preventing the onset of allergic diseases. Recently, the concept of "immune tolerance" has replaced this old theory, and induction of tolerance by exposure is actually considered the appropriate method for preventing atopic diseases and other immunomediated pathologies. On the other hand, it is obvious that for public health reasons, abandoning current medical and hygienic practices is not desirable; therefore, safe alternatives, such as probiotics, have been suggested for providing necessary microbial stimulation.

OBJECTIVE

The purpose of our review is to describe the immunomodulatory and anti-inflammatory properties of probiotics, reporting literature data on their effect when used for the treatment of immunomediated diseases.

MATERIALS AND METHODS

Articles reporting the evidence on the use of probiotics in immunomediated diseases, such as atopy, cow's milk allergy and rheumatoid arthritis (RA), and in inflammatory diseases, such as inflammatory bowel diseases (IBDs), with or without statistical meta-analysis, were selected in three different search engines: (1) MEDLINE via PubMed interface, (2) Scopus and (3) Google Scholar for all articles published from inception to July 2013. Titles and abstracts of identified papers were screened by two independent reviewers to determine whether they met the eligibility criteria of interest to develop our review. Subsequently, full texts of the remaining articles were independently retrieved for eligibility by the two reviewers.

RESULTS AND DISCUSSION

The recent literature is focusing its interest towards the immunologic properties of relatively harmless organisms, including lactobacilli and bifidobacteria, helminths and saprophytic mycobacteria that may skew immune responses towards immunoregulation by inducing Treg cells, rather than eliciting a pro-inflammatory immune response. For this reason, recent researches have been addressed on the use of probiotics to promote immunoregulation in atopic diseases, such as atopic/eczema dermatitis syndrome and food allergy, as well as in inflammatory-based diseases such as IBDs, RA and bronchial asthma.

Mucosal immunology of food allergy

Food allergies are increasing in prevalence at a higher rate than can be explained by genetic factors, suggesting a role for as yet unidentified environmental factors. In this review, we summarize the state of knowledge about the healthy immune response to antigens in the diet and the basis of immune deviation that results in immunoglobulin E (IgE) sensitization and allergic reactivity to foods. The intestinal epithelium forms the interface between the external environment and the mucosal immune system, and emerging data suggest that the interaction between intestinal epithelial cells and mucosal dendritic cells is of particular importance in determining the outcome of immune responses to dietary antigens. Exposure to food allergens through non-oral routes, in particular through the skin, is increasingly recognized as a potentially important factor in the increasing rate of food allergy. There are many open questions on the role of environmental factors, such as dietary factors and microbiota, in the development of food allergy, but data suggest that both have an important modulatory effect on the mucosal immune system. Finally, we discuss recent developments in our understanding of immune mechanisms of clinical manifestations of food allergy. New experimental tools, particularly in the field of genomics and the microbiome, are likely to shed light on factors responsible for the growing clinical problem of food allergy.

Three main factors define changes in fecal microbiota associated with feeding modality in infants

OBJECTIVES

There are many differences in the fecal infant microbiota associated with various feeding methods. The aim of this study was to examine the major differences in the fecal microbiota of breast-fed (BF) and formula-fed (FF) infants and to describe the principal bacterial components that would explain the variability in the predominant bacterial families and genus clusters.

METHODS

Fecal samples from 58 infants, 31 of whom were exclusively BF and 27 of whom were exclusively FF with a standard formula in agreement with the European Society for Pediatric Gastroenterology, Hepatology, and Nutrition recommendations, were analyzed by fluorescent in situ hybridization combined with flow cytometry. Principal component analysis was used to maximize the information gained for the predominant bacterial families and genus clusters using a minimal number of bacterial groups.

RESULTS

The predominant detected group was Bifidobacterium, followed by Enterobacteriaceae and Bacteroides in both BF and FF infants. The Lactobacillus group was the only independent variable associated with FF infants. We also found that 3 principal components were sufficient to describe the association between the bacterial group, genus, and species studied in BF and FF infants; however, these components differed between BF and FF infants. For the former, the 3 factors found were Bifidobacterium/Enterobacteriaceae, Lactobacillus/Bacteroides, and Clostridium coccoides/Atopobium; for the latter, Bifidobacterium/Enterobacteriaceae, Bacteroides and C coccoides were observed.

CONCLUSIONS

There is a clear clustering of components of infant microbiota based on the feeding method.

Establishment of the intestinal microbiota and its role for atopic dermatitis in early childhood

BACKGROUND

Perturbations in the intestinal microbiota may disrupt mechanisms involved in the development of immunologic tolerance. The present study aimed to examine the establishment of the infant microbiota and its association to the development of atopic dermatitis (AD).

METHODS

Within a randomized, placebo-controlled trial on the prevention of AD by oral supplementation of a bacterial lysate between week 5 and the end of month 7, feces was collected at the ages of 5 weeks (n = 571), 13 weeks (n = 332), and 31 weeks (n = 499) and subjected to quantitative PCRs to detect bifidobacteria, bacteroides, lactobacilli, Escherichia coli, Clostridium difficile, and Clostridium cluster I.

RESULTS

Birth mode, breast-feeding but also birth order had a strong effect on the microbiota composition. With increasing number of older siblings the colonization rates at age 5 weeks of lactobacilli (P < .001) and bacteroides (P = .02) increased, whereas rates of clostridia decreased (P < .001). Colonization with clostridia, at the age of 5 and 13 weeks was also associated with an increased risk of developing AD in the subsequent 6 months of life (odds ratioadjusted = 2.35; 95% CI, 1.36-3.94 and 2.51; 1.30-4.86, respectively). Mediation analyses demonstrated that there was a statistically significant indirect effect via Clostridium cluster I colonization for both birth mode and birth order in association to AD.

CONCLUSION

The results of this study are supportive for a role of the microbiota in the development of AD. Moreover, the "beneficial" influence of older siblings on the microbiota composition suggests that this microbiota may be one of the biological mechanisms underlying the sibling effect.

The association of gut microbiota with body weight and body mass index in preschool children of Estonia

Background

The gut microbiota has been shown to affect both fat storage and energy harvesting, suggesting that it plays a direct role in the development of obesity. The aim of this study was to investigate whether intestinal colonization by particular species/groups of the intestinal microbiota is related to body weight values in Estonian preschool children born in different years during the entire 1990s.

Methods

Body weight, height, body mass index (BMI), and quantitative composition of cultivable gut microbiota (staphylococci, enterococci, streptococci, enterobacteria, lactobacilli, anaerobic gram-positive cocci, bifidobacteria, eubacteria, bacteroides, clostridia, and candida) were studied in 51 healthy 5-year-old children (40 were born between 1993 and 94 and 11 were born between 1996 and 97).

Results

At the age of 5 years, median weight was 19.5 kg and median BMI was 15.3 kg/m². Significantly higher BMI (p=0.006) was found in 5-year-old children born in late versus early 1990s during the development of socioeconomic situation of Estonia (2% rise in gross domestic product). The counts of the different gut bacteria did not show any association with weight and BMI in the 5-year-old children. However, the BMI values were in positive correlation with a relative share of anaerobic gram-positive bacteria, for example, bifidobacteria when adjusted for sex and year of birth (adj R²=0.459, p=0.026) and eubacteria (adj R²=0.484, p=0.014) in the community of cultured intestinal microbiota. The relative share of bacteroides showed a negative correlation with the childrens’ weight (adj R²=− 0.481, p=0.015).

Conclusion

The body weight indices of preschool children of the general population are associated with the proportion of anaerobic intestinal microbiota and can be predicted by sex and particular socioeconomic situation from birth to 5 years of age.

Probiotics in the treatment and prevention of allergy in children

Several fold increase in allergic diseases in developed, high-income countries during recent decades is attributed to environmental changes such as urbanization with improved hygiene. This, together with conquering severe bacterial infections during childhood, has reduced the microbial stimulation of the developing immune system of infants. Studies on the pathogenesis of allergy both in man and experimental animal have shown the importance of commensal bacteria in the gastrointestinal tract in stimulating and directing the immune system. The interest in modulating commensal bacterial flora with probiotics to prevent and treat allergy has multiplied in recent years.

In the present review we report results on randomized, controlled studies in which childhood atopic eczema was treated or which aimed to prevent development of allergy during childhood.

Nine studies with 639 patients have looked at the effect of probiotics in treatment of eczema. While 3 studied showed no effect, other studies suggested a moderate benefit of the use of probiotics on the severity of eczema. Studies suggested that the effect may be seen particularly in patients with food allergy and/or sensitization.

Nine studies have reported on the prevention of allergy on 6 study population with altogether 1989 high risk infants. While the early study reporting the development of allergy at ages 2, 4 and 7 years showed a marked reduction of eczema in 77 treated infants, later studies have failed to show similar success. Two studies showed no effect. In the largest study with more than 900 children at age 2 atopic eczema was reduced by 20%, but at age 5 positive effect was present in only the subgroup of children who had born by cesarean section. None of studies has reported adverse effects of probiotics in infants.

Result in both treatment and prevention studies are quite variable, the major reason being the use of different strains of probiotic bacteria and varying types of intervention. Even if the results are encouraging, we need a stronger effect. This may be reached by finding new strains of probiotics affecting stronger stimulation of immune system, together with longer lasting and varying treatment schedules. However, safety issues have to be observed.

Meconium microbiota types dominated by lactic acid or enteric bacteria are differentially associated with maternal eczema and respiratory problems in infants

BACKGROUND

Culture-dependent methods have shown that meconium, the newborn's first intestinal discharge, is not sterile, but the diversity of bacteria present in this material needs to be further characterized by means of more sensitive molecular techniques.

OBJECTIVE

Our aims were to characterize molecularly the meconium microbiota in term infants, to assess whether it contributes to the future microbiota of the infants' gastrointestinal tract, and to evaluate how it relates to lifestyle variables and atopy-related conditions.

METHODS

We applied high-throughput pyrosequencing of the 16S rRNA gene to study the meconium microbiota in twenty term newborns from a Spanish birth cohort. For comparison, we characterized the microbiota in fecal samples from seven pregnant women days before delivery and in two series of infant samples spanning the first seven months of life. We also compared our data with vaginal and skin microbiota characterized in independent studies. Different types of meconium microbiota were defined based on taxonomic composition and abundance and their associations with different factors were statistically evaluated.

RESULTS

The meconium microbiota differs from those in adult feces, vagina and skin, but resembles that of fecal samples from young infants. Meconium samples clustered into two types with different bacterial diversity, richness and composition. One of the types was less diverse, dominated by enteric bacteria and associated with a history of atopic eczema in the mother (P = 0.038), whereas the second type was dominated by lactic acid bacteria and associated with respiratory problems in the infant (P = 0.040).

CONCLUSIONS & CLINICAL RELEVANCE

Our findings suggest that the meconium microbiota has an intrauterine origin and participates in gut colonization. Although based on a small population sample, our association analyses also suggest that the type of bacteria detected in meconium is influenced by maternal factors and may have consequences for childhood health.

Microarray analysis reveals marked intestinal microbiota aberrancy in infants having eczema compared to healthy children in at-risk for atopic disease

BACKGROUND

Deviations in composition and diversity of intestinal microbiota in infancy have been associated with both the development and recurrence of atopic eczema. Thus, we decided to use a deep and global microarray-based method to characterize the diversity and temporal changes of the intestinal microbiota in infancy and to define specific bacterial signatures associated with eczema. Faecal microbiota at 6 and 18 months of age were analysed from 34 infants (15 with eczema and 19 healthy controls) selected from a prospective follow-up study based on the availability of faecal samples. The infants were originally randomized to receive either Lactobacillus rhamnosus GG or placebo.

RESULTS

Children with eczema harboured a more diverse total microbiota than control subjects as assessed by the Simpson's reciprocal diversity index of the microarray profiles. Composition of the microbiota did not differ between study groups at age of 6 months, but was significantly different at age of 18 months as assessed by MCPP (p=0.01). At this age healthy children harboured 3 -fold greater amount of members of the Bacteroidetes (p=0.01). Microbiota of children suffering from eczema had increased abundance of the Clostridium clusters IV and XIVa, which are typically abundant in adults. Probiotic Lactobacillus rhamnosus GG supplementation in early infancy was observed to have minor long-term effects on the microbiota composition.

CONCLUSION

A diverse and adult-type microbiota in early childhood is associated with eczema and it may contribute to the perpetuation of eczema.

Normal neonatal microbiome variation in relation to environmental factors, infection and allergy

PURPOSE OF REVIEW

Bacterial colonization of the infant intestinal tract begins at birth. We are at the forefront of understanding complex relationships between bacteria and multiple parameters of health of the developing infant. Moreover, the establishment of the microbiome in the critical neonatal period is potentially foundational for lifelong health and disease susceptibility. Recent studies utilizing state-of-the-art culture-independent technologies have begun to increase our knowledge about the gut microbiome in infancy, the impact of multiple exposures, and its effects on immune response and clinical outcomes such as allergy and infection.

RECENT FINDINGS

Postnatal exposures play a central role in the complex interactions between the nearly blank canvas of the neonatal intestine, whereas genetic factors do not appear to be a major factor. Infant microbial colonization is affected by delivery mode, dietary exposures, antibiotic exposure, and environmental toxicants. Successive microbiome acquisition in infancy is likely a determinant of early immune programming, subsequent infection, and allergy risk.

SUMMARY

The novel investigation of the neonatal microbiome is beginning to unearth substantial information, with a focus on immune programming that coevolves with the developing microbiome early in life. Several exposures common to neonatal and infant populations could exert pressure on the development of the microbiome and major diseases including allergy and infection in large populations.

Reduced gut microbial diversity in early life is associated with later development of eczema but not atopy in high-risk infants

BACKGROUND

Alterations in intestinal microflora have been linked to the development of allergic disease. Recent studies suggest that healthy infant immune development may depend on the establishment of a diverse gut microbiota rather than the presence or absence of specific microbial strains.

OBJECTIVES

We investigated the relationship between diversity of gut microbiota in the early postnatal period and subsequent development of eczema and atopy in the first year of life.

METHODS

Fecal samples were collected 1 wk after birth from 98 infants at high risk of allergic disease, who were followed prospectively to age 12 months. Fecal microbial diversity was assessed by terminal restriction fragment length polymorphism (T-RFLP) using restriction enzymes Sau96I and AluI, with a greater number of peaks representing greater diversity of bacterial communities.

RESULTS

Microbial diversity at day 7 was significantly lower in infants with eczema at age 12 months as compared to infants without eczema (AluI mean number of peaks 13.1 vs. 15.5, p = 0.003, 95% CI for difference in means -3.9, -0.8; Sau96I 14.7 vs. 17.2, p = 0.03, 95% CI -4.9, -0.3). No differences were observed for atopic compared to non-atopic infants, or infants with two allergic parents compared to those with one or no allergic parent.

CONCLUSIONS

A more diverse intestinal microbiota in the first week of life is associated with a reduced risk of subsequent eczema in infants at increased risk of allergic disease. Interventions that enhance microbial diversity in early life may provide an effective means for the prevention of eczema in high-risk infants.

Effects of Lactobacillus rhamnosus GG supplementation on cow's milk allergy in a mouse model

BACKGROUND

Cow's milk allergy (CMA) is one of the most prevalent human food-borne allergies, particularly in infants and young children from developed countries. Our study aims to evaluate the effects of Lactobacillus rhamnosus GG (LGG) administration on CMA development using whole cow's milk proteins (CMP) sensitized Balb/C mice by two different sensitization methods.

METHODS

LGG supplemented mice were either sensitized orally with CMP and cholera toxin B-subunit (CTB) as adjuvant, or intraperitoneally (IP) with CMP but without the adjuvant. Mice were then orally challenged with CMP and allergic responses were accessed by monitoring hypersensitivity scores, measuring the levels of CMP-specific immunoglobulins (IgG1, IgG2a and IgG) and total IgE from sera, and cytokines (IL-4 and IFN-γ) from spleen lysates.

RESULTS

Sensitization to CMP was successful only in IP sensitized mice, but not in orally sensitized mice with CMP and CTB. Interestingly, LGG supplementation appeared to have reduced cow's milk allergy (CMA) in the IP group of mice, as indicated by lowered allergic responses.

CONCLUSIONS

Adjuvant-free IP sensitization with CMP was successful in inducing CMA in the Balb/C mice model. LGG supplementation favourably modulated immune reactions by shifting Th2-dominated trends toward Th1-dominated responses in CMP sensitized mice. Our results also suggest that oral sensitization by the co-administration of CMP and CTB, as adjuvant, might not be appropriate to induce CMA in mice.

Probiotics in the treatment and prevention of allergies in children

Several studies on the pathogenesis of allergy both in man and experimental animals continue to show the importance of commensal bacteria in the gastrointestinal tract in stimulating and directing the immune system. The interest in modulating commensal bacteria flora with pre- and probiotics to prevent and treat food allergy has multiplied in recent years. We recently studied 230 infants with atopic dermatitis and suspected cow’s milk allergy. The infants were randomly allocated to groups which received Lactobacillus GG (LGG), a mixture of four probiotic strains (MIX) or placebo for 4 weeks. We inferred that probiotics induce systemically detectable low-grade inflammation, which may explain the clinical effects and the secretion pattern of cytokines induced by PBMC. To study the ability of probiotics to prevent allergy in children, we recruited 1223 pregnant women carrying fetuses at increased risk of allergy for a double-blind placebo-controlled trial. Mothers used a mixture of four probiotic bacteria or a placebo from the 36th week of gestation. Their infants received the same probiotics plus prebiotic galacto-oligosaccharides for 6 months. At the 2-year follow-up, a total of 925 infants participated. The cumulative incidence of allergic disease did not differ significantly between the synbiotic and the placebo group. However, synbiotics significantly reduced eczema. The preventive effect of synbiotics was more pronounced against IgE-associated diseases. At the 5 year follow-up, 891(88%) of the 1018 intention-to-treat infants attended. In the probiotic and placebo groups, frequencies of allergic symptoms and IgE-associated allergic disease and sensitization were similar, and the frequencies of eczema did not differ between the groups. Atopic eczema, allergic rhinitis and asthma appeared equal frequency in the groups. However, less IgE-associated allergic disease occurred in the cesarean-delivered infants given probiotics. In cesarean-delivered childen, we noticed a delayed rise in bifidobacteria recovery in placebo-treated children which was corrected by pro- and prebiotic supplementation. Indications from studies of feces and blood at the age 6 months suggest that probiotics may enhance both inflammation and immune defence of the gut. The probiotic treatment further stimulated maturation of the immune system since the infants given probiotics showed increased resistance to respiratory infections and improved vaccine antibody responses.

Intestinal defensin secretion in infancy is associated with the emergence of sensitization and atopic dermatitis

BACKGROUND

Intestinal flora and innate immunity, and their interactions impact adaptive immunity.

OBJECTIVE

To study the association of fecal defensin levels in infancy with synbiotic treatment and with the emergence of atopy.

METHODS

The randomly selected group of 102 infants belonged to a randomized, double-blind placebo-controlled trial where 1223 infants in high risk for allergy received, from birth to 6 months, a mixture of synbiotics, or placebo. Clinical trials registration number for the clinical trial is NCT00298337. In the subgroup, 45 received active treatment and 56 received placebo treatment. Follow-up for the emergence of sensitization and allergic diseases lasted 5 years. At the age of 3 (n = 96) and 6 (n = 87) months, we measured fecal levels of human neutrophil peptide (HNP) 1-3 and of β-defensin 2 (HBD2) using enzyme linked immunosorbent assays and concentrations of lactic acid bacteria on MRS agar. We used multifactorial regression in data analysis.

RESULTS

Fecal levels of HNP1-3 and HBD2 decreased from the age of 3-6 months (P < 0.0001). HBD2 levels decreased less in the synbiotics group compared with placebo (P < 0.02). High fecal HBD2 levels at 6 months were associated with an increased risk for sensitization by the age of 5 years (OR 2.5, 95% confidence interval 1.1-5.8, P < 0.03). High fecal HNP1-3 levels at 6 months were associated with a decreased risk for atopic dermatitis (OR 0.4, 95% CI 0.1-1.0, P < 0.05). Samples with very low or high HBD2 levels at 6 months had low concentrations of lactic acid bacteria (P < 0.02).

CONCLUSIONS AND CLINICAL RELEVANCE

Early innate immunity responses in the gut are associated with the emergence of sensitization and atopic dermatitis later in childhood.

Faecal microbiota and short-chain fatty acid levels in faeces from infants with cow's milk protein allergy

BACKGROUND

The present study was designed to compare the faecal microbiota and concentrations of faecal short-chain fatty acid and ammonia between healthy and cow's milk protein allergic (CMPA) infants.

METHODS

The population comprised 92 infants aged 2-12 months who were nonallergic (n = 46) or diagnosed as having CMPA (n = 46). Faecal samples were analyzed by fluorescent in situ hybridization and flow cytometry, using a panel of 10 rRNA targeted group- and species-specific oligonucleotide probes. Acetic, propionic, butyric, isocaproic and branched-chain short fatty acids (BCSFA) were measured by gas-liquid chromatography, lactate by enzymatic reaction, and pH and ammonia levels were determined.

RESULTS

CMPA infant faeces had significantly higher proportions of the Clostridium coccoides group and Atopobium cluster and a higher sum of the proportions of the different bacterial groups in comparison to healthy infant faeces. Faecal pH and ammonia did not significantly differ between CMPA and healthy infants. Faeces concentrations and percentages of butyric acid and BCSFA were higher in CMPA infants than in healthy infants.

CONCLUSIONS

The findings clearly set a link between a dysbiosis in gut microbiota composition and the pathogenesis of CMPA. No single species or genus appeared to play an essential role, but dysbiosis led to biomarkers of CMPA among bacterial fermentation products.

Effect of formula composition on the development of infant gut microbiota

OBJECTIVES

Breast-feeding induces a gut microbiota rich in bifidobacteria, whereas formula-fed babies have a more diverse colonization. This ecosystem contributes to the development of the immune response and the lower incidence of diarrhea and allergy in breast-fed infants. This randomized double-blind controlled trial aimed to evaluate the bifidogenic effect of a mainly whey protein study formula low in phosphate and protein, allowing a composition closer to that of human milk.

PATIENTS AND METHODS

One hundred ninety healthy infants exclusively received study formula with or without Bifidobacterium longum (BL999), or a control formula for up to 4 months. Breast-fed infants served as a reference population. Stool samples collected at 2 months of age were analyzed for bacterial counts (log colony-forming unit [CFU]/g).

RESULTS

Bifidobacteria counts were significantly higher in infants receiving the study formula alone (10.0[0.8], P < 0.0001, median [interquartile range]) or with BL999 (9.8[1.4], P < 0.01) than control (9.2[3.5]), and were similar to breast-fed infants (10.1[0.4], P > 0.05). The difference between the 2 study groups was 0.16 log CFU/g (90% confidence interval [CI] [0-0.4]), within the predefined equivalence margin. Microbiota profile, as a percentage of total bacteria counts, showed about 50% Bifidobacteria, 8% Enterobacteria, and <10% Clostridia in study formulae and breast-fed infants versus 22%, 13%, and 19% in controls, respectively. There were no significant differences in growth measurements, digestive tolerance, and adverse events between groups.

CONCLUSIONS

This study showed that infant formula closer resembling human milk was more bifidogenic than the control formula and led to a microbiota profile similar to that for breast-fed infants.

Optimising bacterial DNA extraction from faecal samples: comparison of three methods

Culture independent methods are used widely in diagnostic laboratories for infectious disease Isolation of genomic DNA from clinical samples is the first and important step in the procedure. Several procedures for extracting DNA from faecal samples have been described, including different mechanical cell disruptors. To our knowledge, the use of TissueLyser as a mechanical disruptor on faecal samples before DNA extraction has not been previously described. The purpose of the study was to implement a method for preparing faecal samples for optimal DNA extraction. Thus, three different procedures for extracting DNA from human faeces were compared. This was done either by using the mechanical disrupter by Mini BeadBeater 8, or the TissueLyser both followed by DNA purification using QIAamp DNA stool MiniKit, in comparison with DNA extractions using QIAamp DNA stool MiniKit without any prior mechanical disruption, according to manufacturer’s instructions. The obtained DNA from the three procedures was analysed by DGGE, and the number of bands was compared between each procedure. There was no significant difference between the numbers of bacterial bands obtained from DGGE when using a TissueLyser or Mini BeadBeater 8, so the two different mechanical cell disruptors can be used comparably when isolating bacterial DNA from faecal samples. The QIAamp DNA stool MiniKit alone resulted in a reduced number of bands compared to the two mechanical disruption methods.