Effect of probiotic mix (Bifidobacterium bifidum, Bifidobacterium lactis, Lactobacillus acidophilus) in the primary prevention of eczema: a double-blind, randomized, placebo-controlled trial

Neonatal gut microbiota and risk of developing food sensitization and allergy

BACKGROUND

Food sensitization (FS) develops in early infancy and is a risk factor for subsequent food allergy (FA). Recent evidence suggests relationships of gut microbiota with FS and FA. However, little is known about the role of neonatal gut microbiota in the pathobiology of these manifestations.

OBJECTIVES

We sought to characterize gut microbiota in children using an enterotyping approach and determine the association of gut microbiota and the enterotypes with the development of FS and FA.

METHODS

We combined gut microbiome and fecal short-chain fatty acid data from 2 longitudinal birth-cohort studies in Japan, clustered the microbiome data from children who were 1 week to 7 years old and their mothers and identified enterotypes. We also determined the associations of gut microbiota and enterotypes with risks of developing FS and FA across the 2 studies using multivariable regression models.

RESULTS

Data from the 2563 microbiomes identified 6 enterotypes. More gut bacteria (eg, Bifidobacterium) in 1-month-old children showed significant relationships with the development of FS and FA than in 1-week-old children. Enterotypes at 1 month old consisted of Bacteroides-dominant, Klebsiella-dominant, and Bifidobacterium-dominant enterotypes. Bifidobacterium-dominant enterotypes with the highest fecal propionate concentration had the lowest risks of developing FS and FA, especially of hen egg white sensitization. Bifidobacterium-dominant enterotypes had lower risks at 2 years old in one study (vs Bacteroides-dominant enterotype, adjusted odds ratio [adjOR]: 0.10, 95% CI: 0.01-0.78; vs Klebsiella-dominant enterotype, adjOR: 0.10, 95% CI: 0.01-0.77) and at 9 months old in the other study (vs Bacteroides-dominant enterotype, adjOR: 0.33, 95% CI: 0.11-0.91).

CONCLUSIONS

In these birth-cohort studies, gut microbiome clustering identified distinct neonatal enterotypes with differential risks of developing FS and FA.

Probiotics supplementation during pregnancy or infancy on multiple food allergies and gut microbiota: a systematic review and meta-analysis

CONTEXT

Probiotics show promise in preventing and managing food allergies, but the impact of supplementation during pregnancy or infancy on children's allergies and gut microbiota remains unclear.

OBJECTIVE

This study aimed to assess the effects of maternal or infant probiotic supplementation on food allergy risk and explore the role of gut microbiota.

DATA SOURCES

A systematic search of databases (PubMed, Cochrane Library, Embase, and Medline) identified 37 relevant studies until May 20, 2023.

DATA EXTRACTION

Two independent reviewers extracted data, including probiotics intervention details, gut microbiota analysis, and food allergy information.

DATA ANALYSIS

Probiotics supplementation during pregnancy and infancy reduced the risk of total food allergy (relative risk [RR], 0.79; 95% CI, 0.63-0.99), cow-milk allergy (RR, 0.51; 95% CI, 0.29-0.88), and egg allergy (RR, 0.57; 95% CI, 0.39-0.84). Infancy-only supplementation lowered cow-milk allergy risk (RR, 0.69; 95% CI, 0.49-0.96), while pregnancy-only had no discernible effect. Benefits were observed with over 2 probiotic species, and a daily increase of 1.8 × 109 colony-forming units during pregnancy and infancy correlated with a 4% reduction in food allergy risk. Children with food allergies had distinct gut microbiota profiles, evolving with age.

CONCLUSIONS

Probiotics supplementation during pregnancy and infancy reduces food allergy risk and correlates with age-related changes in gut microbial composition in children.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO registration no. CRD42023425988.

Effects of probiotics on the prevention and treatment of children with allergic rhinitis: a meta-analysis of randomized controlled trials

Background and aim

Recent studies have demonstrated the anti-allergic effects of probiotics in humans. However, their role in preventing and treating pediatric allergic rhinitis has not been thoroughly investigated. This study aimed to systematically review the efficacy and preventive effects of probiotics on pediatric allergic rhinitis.

Methods

We systematically searched PubMed, Embase, the Cochrane Central Register of Controlled Trials, and Web of Science databases for all relevant studies on probiotics and pediatric allergic rhinitis. Studies meeting the inclusion criteria were included, data were extracted, and meta-analyses were performed.

Results

A total of 28 studies with 4,765 participants were included in this study. The pooled results showed that the use of probiotics was associated with a significant improvement in total nose symptom scores (SMD, -2.27; 95% CI, -3.26 to -1.29; P < 0.00001), itchy nose scores (SMD, -0.44; 95% CI, -0.80 to -0.07; P = 0.02), sneezing scores (SMD, -0.47; 95% CI, -0.84 to -0.10; P = 0.01), eye symptoms (SMD, -3.77; 95% CI, -5.47 to -2.07; P < 0.00001), and Pediatric Rhinoconjunctivitis Quality of Life Questionnaire (SMD, -2.52; 95% CI, -4.12 to -0.92; P < 00001). However, the use of probiotics was not associated with the incidence of allergic rhinitis (RR, 0.9; 95% CI, 0.74-1.08; P = 0.26).

Conclusions

The present study demonstrated that probiotics were effective and safe for improving pediatric allergic rhinitis symptoms and quality of life. However, probiotics could not prevent pediatric allergic rhinitis.

Effect of Bifidobacterium bifidum Supplementation in Newborns Born from Cesarean Section on Atopy, Respiratory Tract Infections, and Dyspeptic Syndromes: A Multicenter, Randomized, and Controlled Clinical Trial

Cesarean section is considered a possible trigger of atopy and gut dysbiosis in newborns. Bifidobacteria, and specifically B. bifidum, are thought to play a central role in reducing the risk of atopy and in favoring gut eubiosis in children. Nonetheless, no trial has ever prospectively investigated the role played by this single bacterial species in preventing atopic manifestations in children born by cesarean section, and all the results published so far refer to mixtures of probiotics. We have therefore evaluated the impact of 6 months of supplementation with B. bifidum PRL2010 on the incidence, in the first year of life, of atopy, respiratory tract infections, and dyspeptic syndromes in 164 children born by cesarean (versus 249 untreated controls). The results of our multicenter, randomized, and controlled trial have shown that the probiotic supplementation significantly reduced the incidence of atopic dermatitis, upper and lower respiratory tract infections, and signs and symptoms of dyspeptic syndromes. Concerning the gut microbiota, B. bifidum supplementation significantly increased α-biodiversity and the relative values of the phyla Bacteroidota and Actinomycetota, of the genus Bacteroides, Bifidobacterium and of the species B. bifidum and reduced the relative content of Escherichia/Shigella and Haemophilus. A 6-month supplementation with B. bifidum in children born by cesarean section reduces the risk of gut dysbiosis and has a positive clinical impact that remains observable in the following 6 months of follow-up.

Dietary Interventions in Atopic Dermatitis: A Comprehensive Scoping Review and Analysis

BACKGROUND

This scoping review aims to critically assess gaps in the current literature on atopic dermatitis (AD) by evaluating the overall effectiveness of dietary interventions. Through a comprehensive analysis that follows the Preferred Reporting Item for Systematic Review and Meta-Analyses Extension for Scoping Reviews (PRISMA-ScR) guidelines, we conducted a thorough search on the Web of Science database in May 2023 using specific search strategies to identify all relevant studies on the research topic.

SUMMARY

A total of 104 full-text articles were included for review. Our synthesis identified seven notable categories of dietary interventions for AD, showcasing the diversity of interventions utilized. This includes vitamin supplementation, probiotic and prebiotic supplementation, dietary fat, biological compounds, foods from natural sources, major nutrients, and diet-related approaches. Further analyses stratified by targeted populations revealed a predominant focus on pediatrics, particularly in probiotic supplementation, and on adults, with an emphasis on vitamin D and E supplementation.

KEY MESSAGES

Despite most dietary interventions demonstrating overall effectiveness in improving AD severity and its subjective symptoms, several significant gaps were identified. There was a scarcity of studies on adults and whole-diet interventions, a prevalence of short-term interventions, heterogeneity in study outcomes, designs, and population, occasional disparity between statistical significance and clinical relevance, and a lack of a comprehensive multidisciplinary approach. Nonetheless, these findings offer valuable insights for future AD research, guiding additional evidence-driven dietary interventions and informing healthcare professionals, researchers, and individuals, advancing both understanding and management of AD.

The Interaction between the Host Genome, Epigenome, and the Gut-Skin Axis Microbiome in Atopic Dermatitis

Atopic dermatitis (AD) is a chronic inflammatory skin disease that occurs in genetically predisposed individuals. It involves complex interactions among the host immune system, environmental factors (such as skin barrier dysfunction), and microbial dysbiosis. Genome-wide association studies (GWAS) have identified AD risk alleles; however, the associated environmental factors remain largely unknown. Recent evidence suggests that altered microbiota composition (dysbiosis) in the skin and gut may contribute to the pathogenesis of AD. Examples of environmental factors that contribute to skin barrier dysfunction and microbial dysbiosis in AD include allergens, irritants, pollution, and microbial exposure. Studies have reported alterations in the gut microbiome structure in patients with AD compared to control subjects, characterized by increased abundance of Clostridium difficile and decreased abundance of short-chain fatty acid (SCFA)-producing bacteria such as Bifidobacterium. SCFAs play a critical role in maintaining host health, and reduced SCFA production may lead to intestinal inflammation in AD patients. The specific mechanisms through which dysbiotic bacteria and their metabolites interact with the host genome and epigenome to cause autoimmunity in AD are still unknown. By understanding the combination of environmental factors, such as gut microbiota, the genetic and epigenetic determinants that are associated with the development of autoantibodies may help unravel the pathophysiology of the disease. This review aims to elucidate the interactions between the immune system, susceptibility genes, epigenetic factors, and the gut microbiome in the development of AD.

Microbiome Alterations Driven by Trypanosoma cruzi Infection in Two Disjunctive Murine Models

Alterations caused by Trypanosoma cruzi in the composition of gut microbiome may play a vital role in the host-parasite interactions that shapes physiology and immune responses against infection. Thus, a better understanding of this parasite-host-microbiome interaction may yield relevant information in the comprehension of the pathophysiology of the disease and the development of new prophylactic and therapeutic alternatives. Therefore, we implemented a murine model with two mice strains (BALB/c and C57BL/6) to evaluate the impact of Trypanosoma cruzi (Tulahuen strain) infection on the gut microbiome utilizing cytokine profiling and shotgun metagenomics. Higher parasite burdens were observed in cardiac and intestinal tissues, including changes in anti-inflammatory (interleukin-4 [IL-4] and IL-10) and proinflammatory (gamma interferon, tumor necrosis factor alpha, and IL-6) cytokines. Bacterial species such as Bacteroides thetaiotaomicron, Faecalibaculum rodentium, and Lactobacillus johnsonii showed a decrease in relative abundance, while Akkermansia muciniphila and Staphylococcus xylosus increased. Likewise, as infection progressed, there was a decrease in gene abundances related to metabolic processes such as lipid synthesis (including short-chain fatty acids) and amino acid synthesis (including branched-chain amino acids). High-quality metagenomic assembled genomes of L. johnsonii and A. muciniphila among other species were reconstructed, confirming, functional changes associated with metabolic pathways that are directly affected by the loss of abundance of specific bacterial taxa. IMPORTANCE Chagas disease (CD) is caused by the protozoan Trypanosoma cruzi, presenting acute and chronic phases where cardiomyopathy, megaesophagus, and/or megacolon stand out. During the course of its life cycle, the parasite has an important gastrointestinal tract transit that leads to severe forms of CD. The intestinal microbiome plays an essential role in the immunological, physiological, and metabolic homeostasis of the host. Therefore, parasite-host-intestinal microbiome interactions may provide information on certain biological and pathophysiological aspects related to CD. The present study proposes a comprehensive evaluation of the potential effects of this interaction based on metagenomic and immunological data from two mice models with different genetic, immunological, and microbiome backgrounds. Our findings suggest that there are alterations in the immune and microbiome profiles that affect several metabolic pathways that can potentially promote the infection's establishment, progression, and persistence. In addition, this information may prove essential in the research of new prophylactic and therapeutic alternatives for CD.

Single-Strain Probiotic Lactobacilli for the Treatment of Atopic Dermatitis in Children: A Systematic Review and Meta-Analysis

Probiotics are known for their positive effects on the gut microbiota. There is growing evidence that the infant gut and skin colonization have a role in the development of the immune system, which may be helpful in the prevention and treatment of atopic dermatitis. This systematic review focused on evaluating the effect of single-strain probiotic lactobacilli consumption on treating children's atopic dermatitis. Seventeen randomized placebo-controlled trials with the primary outcome of the Scoring Atopic Dermatitis (SCORAD) index were included in the systematic review. Clinical trials using single-strain lactobacilli were included. The search was conducted until October 2022 using PubMed, ScienceDirect, Web of Science, Cochrane library and manual searches. The Joanna Briggs Institute appraisal tool was used to assess the quality of the included studies. Meta-analyses and sub meta-analyses were performed using Cochrane Collaboration methodology. Due to different methods of reporting the SCORAD index, only 14 clinical trials with 1124 children were included in the meta-analysis (574 in the single-strain probiotic lactobacilli group and 550 in the placebo group) and showed that single-strain probiotic lactobacilli statistically significantly reduced the SCORAD index compared to the placebo in children with atopic dermatitis (mean difference [MD]: -4.50; 95% confidence interval [CI]: -7.50 to -1.49; Z = 2.93; p = 0.003; heterogeneity I² = 90%). The subgroup meta-analysis showed that strains of Limosilactobacillus fermentum were significantly more effective than strains of Lactiplantibacillus plantarum, Lacticaseibacillus paracasei or Lacticaseibacillus rhamnosus. A longer treatment time and younger treatment age statistically significantly reduced symptoms of atopic dermatitis. The result of this systematic review and meta-analysis shows that certain single-strain probiotic lactobacilli are more successful than others in reducing atopic dermatitis severity in children. Therefore, careful consideration to strain selection, treatment time and the age of the treated patients are important factors in enhancing the effectiveness of reducing atopic dermatitis in children when choosing probiotic single-strain lactobacilli.

Role of human milk oligosaccharide metabolizing bacteria in the development of atopic dermatitis/eczema

Despite affecting up to 20% of infants in the United States, there is no cure for atopic dermatitis (AD), also known as eczema. Atopy usually manifests during the first six months of an infant's life and is one predictor of later allergic health problems. A diet of human milk may offer protection against developing atopic dermatitis. One milk component, human milk oligosaccharides (HMOs), plays an important role as a prebiotic in establishing the infant gut microbiome and has immunomodulatory effects on the infant immune system. The purpose of this review is to summarize the available information about bacterial members of the intestinal microbiota capable of metabolizing HMOs, the bacterial genes or metabolic products present in the intestinal tract during early life, and the relationship of these genes and metabolic products to the development of AD/eczema in infants. We find that specific HMO metabolism gene sets and the metabolites produced by HMO metabolizing bacteria may enable the protective role of human milk against the development of atopy because of interactions with the immune system. We also identify areas for additional research to further elucidate the relationship between the human milk metabolizing bacteria and atopy. Detailed metagenomic studies of the infant gut microbiota and its associated metabolomes are essential for characterizing the potential impact of human milk-feeding on the development of atopic dermatitis.

Lactobacillus for the treatment and prevention of atopic dermatitis: Clinical and experimental evidence

Atopic dermatitis (AD) is a chronic inflammatory skin disease, accompanied by itching and swelling. The main pathological mechanism of AD is related to the imbalance between Type 2 helper cells (Th2 cells) and Type 1 helper cells (Th1 cells). Currently, no safe and effective means to treat and prevent AD are available; moreover, some treatments have side effects. Probiotics, such as some strains of Lactobacillus, can address these concerns via various pathways: i) facilitating high patient compliance; ii) regulating Th1/Th2 balance, increasing IL-10 secretion, and reducing inflammatory cytokines; iii) accelerating the maturation of the immune system, maintaining intestinal homeostasis, and improving gut microbiota; and iv) improving the symptoms of AD. This review describes the treatment and prevention of AD using 13 species of Lactobacillus. AD is commonly observed in children. Therefore, the review includes a higher proportion of studies on AD in children and fewer in adolescents and adults. However, there are also some strains that do not improve the symptoms of AD and even worsen allergies in children. In addition, a subset of the genus Lactobacillus that can prevent and relieve AD has been identified in vitro. Therefore, future studies should include more in vivo studies and randomized controlled clinical trials. Given the advantages and disadvantages mentioned above, further research in this area is urgently required.

Citizen Contribution for Searching for Alternative Antimicrobial Activity Substances in Soil

Antimicrobial resistance (AMR) is problematic worldwide, and due to the loss of efficiency of many antibiotics, the pressure to discover alternative antimicrobial molecules has increased. Soil harbors a great biodiversity and biomass of microorganisms, and many antibiotics are produced by soil microbiota. Therefore, soil is a promising reservoir to find new antimicrobial agents. In this respect, novel pedagogical strategies regarding the AMR global crisis have recently been developed in different countries worldwide. Highlighted is the service-learning project "MicroMundo" integrated in a global Citizen Science project called "Tiny Earth". Hence, the present work aimed at determining the antimicrobial activity of soil bacteria, the biodiversity of the selected isolates as putative antimicrobial producers, and their antibiotic resistance profile. Moreover, through the MicroMundo project, we tried to illustrate the relevant link between science and education and the benefits of implementing service-learning methodologies to raise awareness of the AMR problem and to contribute to the search for new alternatives. A total of 16 teachers, 25 university students and 300 secondary school students participated in the search for antimicrobial activity on a collection of 2600 isolates obtained from a total of 130 soil samples analysed. In total, 132 isolates (5% of total tested) were selected as potential antimicrobial producers when two indicator bacteria were used (Escherichia coli and Staphylococcus epidermidis); the most frequent genus among these isolates was Bacillus, followed by Pseudomonas, Paenibacillus and Serratia. The antimicrobial activity (AA) of the 132 potential antimicrobial producers was studied in a second step against 15 indicator bacteria (of six genera and thirteen species, including relevant pathogens). Of the 132 potentially producing bacteria, 32 were selected for further characterization. In this respect, 18 isolates showed low AA, 12 isolates were considered as medium producers, and 2 highly antimicrobial-producing isolates were found (Brevibacillus laterosporus X7262 and Staphylococcus hominis X7276) showing AA against 80% of the 15 indicators tested. Moreover, 48% of the antimicrobial-producing bacteria were susceptible to all antibiotics tested. Due to citizen science, antimicrobial-producing bacteria of great interest have been isolated, managing to raise awareness about the problem of AMR.

Effects of a Novel Infant Formula on Weight Gain, Body Composition, Safety and Tolerability to Infants: The INNOVA 2020 Study

Exclusive breastfeeding is recommended for the first six months of life to promote adequate infant growth and development, and to reduce infant morbidity and mortality. However, whenever some mothers are not able to breastfeed their infants, infant formulas mimicking human milk are needed, and the safety and efficacy of each formula should be tested. Here, we report the results of a multicenter, randomized, blinded, controlled clinical trial that aimed to evaluate a novel starting formula on weight gain and body composition of infants up to 6 and 12 months, as well as safety and tolerability. For the intervention period, infants were divided into three groups: group 1 received formula 1 (Nutribén® Innova 1 (Alter Farmacia S.A., Madrid, Spain) or INN (n = 70)), with a lower amount of protein, a lower casein to whey protein ratio by increasing the content of α-lactalbumin, and a double amount of docosahexaenoic acid/arachidonic acid than the standard formula; it also contained a thermally inactivated postbiotic (Bifidobacterium animalis subsp. lactis, BPL1TM HT). Group 2 received the standard formula or formula 2 (Nutriben® Natal (Alter Farmacia S.A., Madrid, Spain) or STD (n = 70)) and the third group was exclusively breastfed for exploratory analysis and used as a reference (BFD group (n = 70)). During the study, visits were made at 21 days and 2, 4, 6, and 12 months of age. Weight gain was higher in both formula groups than in the BFD group at 6 and 12 months, whereas no differences were found between STD and INN groups either at 6 or at 12 months. Likewise, body mass index was higher in infants fed the two formulas compared with the BFD group. Regarding body composition, length, head circumference and tricipital/subscapular skinfolds were alike between groups. The INN formula was considered safe as weight gain and body composition were within the normal limits, according to WHO standards. The BFD group exhibited more liquid consistency in the stools compared to both formula groups. All groups showed similar digestive tolerance and infant behavior. However, a higher frequency of gastrointestinal symptoms was reported by the STD formula group (n = 291), followed by the INN formula (n = 282), and the BFD groups (n = 227). There were fewer respiratory, thoracic, and mediastinal disorders among BFD children. Additionally, infants receiving the INN formula experienced significantly fewer general disorders and disturbances than those receiving the STD formula. Indeed, atopic dermatitis, bronchitis, and bronchiolitis were significantly more prevalent among infants who were fed the STD formula compared to those fed the INN formula or breastfed. To evaluate whether there were significant differences between formula treatments, beyond growth parameters, it would seem necessary to examine more precise health biomarkers and to carry out long-term longitudinal studies.

Maternal gestational Bifidobacterium bifidum TMC3115 treatment shapes construction of offspring gut microbiota and development of immune system and induces immune tolerance to food allergen

In this study we aimed to determine whether treatment with maternal Bifidobacterium bifidum TMC3115 could affect the composition of the gut microbiota and the development of the immune system and intestinal tract of offspring, and protect the offspring from IgE-mediated allergic disease. Pregnant BALB/c mice were gavaged with TMC3115 until delivery. Offspring were sensitized with ovalbumin from postnatal days 21 to 49. After maternal treatment with TMC3115, the microbiota of the offspring's feces, intestinal contents, and stomach contents (a proxy for breast milk) at the newborn and weaning stages exhibited the most change, and levels of immunoglobulin in the sera and stomach contents and of splenic cytokines, as well as the mRNA levels of colonic intestinal development indicators were all significantly altered in offspring at different stages. After sensitization with ovalbumin, there were no significant changes in the levels of serum IgE or ovalbumin-specific IgE/IgG1 in the TMC3115 group; however, IgM, the expression of intestinal development indicators, and the production of fecal short chain fatty acid (SCFA) were significantly increased, as were the relative abundances of Lactobacillus and the Lachnospiraceae NK4A136 group. Our results suggested that maternal treatment with TMC3115 could have a profound modulatory effect on the composition of the gut microbiota and the development of the immune system and intestinal tissue in offspring at different stages of development, and may induce immune tolerance to allergens in ovalbumin-stimulated offspring by modulating the gut microbiota and SCFA production.

Age-Related NAFLD: The Use of Probiotics as a Supportive Therapeutic Intervention

Human aging, a natural process characterized by structural and physiological changes, leads to alterations of homeostatic mechanisms, decline of biological functions, and subsequently, the organism becomes vulnerable to external stress or damage. In fact, the elderly population is prone to develop diseases due to deterioration of physiological and biological systems. With aging, the production of reactive oxygen species (ROS) increases, and this causes lipid, protein, and DNA damage, leading to cellular dysfunction and altered cellular processes. Indeed, oxidative stress plays a key role in the pathogenesis of several chronic disorders, including hepatic diseases, such as non-alcoholic fatty liver disease (NAFLD). NAFLD, the most common liver disorder in the Western world, is characterized by intrahepatic lipid accumulation; is highly prevalent in the aging population; and is closely associated with obesity, insulin resistance, hypertension, and dyslipidemia. Among the risk factors involved in the pathogenesis of NAFLD, the dysbiotic gut microbiota plays an essential role, leading to low-grade chronic inflammation, oxidative stress, and production of various toxic metabolites. The intestinal microbiota is a dynamic ecosystem of microbes involved in the maintenance of physiological homeostasis; the alteration of its composition and function, during aging, is implicated in different liver diseases. Therefore, gut microbiota restoration might be a complementary approach for treating NAFLD. The administration of probiotics, which can relieve oxidative stress and elicit several anti-aging properties, could be a strategy to modify the composition and restore a healthy gut microbiota. Indeed, probiotics could represent a valid supplement to prevent and/or help treating some diseases, such as NAFLD, thus improving the already available pharmacological intervention. Moreover, in aging, intervention of prebiotics and fecal microbiota transplantation, as well as probiotics, will provide novel therapeutic approaches. However, the relevant research is limited, and several scientific research works need to be done in the near future to confirm their efficacy.

Current Use of Probiotics and Prebiotics in Allergy

The microbiome plays an important role in the pathogenesis of allergic diseases. This review updates the reader on studies aimed at influencing allergic diseases through modulation of the gut microflora. A nonsystematic review of the literature was performed, focusing on relevant trials evaluating the effect of probiotics/prebiotics/symbiotics in the prevention and treatment of allergic disease. For each allergic disease, we were able to find not only a substantial number of clinical trials but also systematic reviews. Specific guidelines, based on systematic reviews and meta-analyses, are available for the prevention of allergic disease and for the treatment of food allergy. In each of the areas examined-allergic rhinitis, allergic asthma, atopic dermatitis, food allergy, and gastrointestinal allergies-there are substantial uncertainties in the efficacy of gut microflora modulation in prevention and treatment. At present, practicing clinicians can avail themselves of intestinal flora modulators as an adjunct in the prevention of atopic dermatitis but not of other forms of allergic diseases. Their effects on the treatment of allergic diseases remain controversial.

Postnatal probiotic supplementation can prevent and optimize treatment of childhood asthma and atopic disorders: A systematic review of randomized controlled trials

BACKGROUND

Although several randomized controlled trials (RCTs) published over the past 5 years show that prenatal or postnatal probiotics may prevent or optimize the treatment of childhood asthma and atopic disorders, findings from the systematic reviews and meta-analyses of these studies appear inconsistent. More recent RCTs have focused on postnatal probiotics, and linked specific probiotic strains to better disease outcomes.

OBJECTIVE

This systematic review aimed to determine if postnatal probiotics are as effective as prenatal probiotics in preventing or treating childhood asthma and atopic disorders.

METHODS

We searched the PubMed, Medline, Google Scholar, and EMBASE databases for RCTs published within the past 5 years (from 2017 to 2022). We included only full-text RCTs on human subjects published in or translated into the English language. We retrieved relevant data items with a preconceived data-extraction form and assessed the methodological quality of the selected RCTs using the Cochrane Collaboration's tool for assessing the risk of bias in randomized trials. We qualitatively synthesized the retrieved data to determine any significant differences in study endpoints of the probiotic and placebo groups.

RESULTS

A total of 1,320 participants (688 and 632 in the probiotic and placebo groups) from six RCTs were investigated. One RCT showed that early Lactobacillus rhamnosus GG (LGG) led to a reduction in the cumulative incidence rate of asthma. Another study demonstrated that mixed strains of Lactobacillus paracasei and Lactobacillus fermentum could support clinical improvement in children with asthma while one trial reported a significant reduction in the frequency of asthma exacerbations using a mixture of Ligilactobacillus salivarius and Bifidobacterium breve. Three trials showed that a combination of LGG and Bifidobacterium animalis subsp lactis, Lactobacillus rhamnosus alone, and a probiotic mixture of Lactobacillus ŁOCK strains improved clinical outcomes in children with atopic dermatitis and cow-milk protein allergy.

CONCLUSIONS

Postnatal strain-specific probiotics (in single or mixed forms) are beneficial in preventing and treating atopic dermatitis and other allergies. Similarly, specific strains are more effective in preventing asthma or improving asthma outcomes. We recommend more interventional studies to establish the most useful probiotic strain in these allergic diseases.

Lactation time influences the composition of Bifidobacterium and Lactobacillus at species level in human breast milk

Human breast milk is a source of microorganisms for infants that play an important role in building infant gut health and immunity. The bacterial composition in human breast milk is influenced by lactation time. This study aimed to investigate the influence of lactation time on bacteria in breast milk at the genus level and the species levels of Bifidobacterium and Lactobacillus on days 2-4, 8, 14, and 30. Eighteen individuals were recruited and 60 milk samples were collected. The 16S rRNA gene, and the bifidobacterial groEL and lactobacilli groEL genes were used for amplicon sequencing. The results revealed that the alpha diversities of colostrum and transition 1 (day 8) milk were lower than that of transition 2 (day 14) and mature milk. PCoA analysis showed that bacterial composition in colostrum and transition 1 milk differed from transition 2 and mature milk. A lower relative abundance of Blautia was found in colostrum and transition 1 milk compared with mature milk and lower abundances of Ruminococcus, Dorea, and Escherichia-Shigella were found in transition 1 compared with mature milk. Bifidobacterium ruminantium, Limosilactobacillus mucosae, and Ligilactobacillus ruminis were the predominant species across all four lactation stages, while Bifidobacterium bifidum was lower in transition 1, and Bifidobacterium pseudocatenulatum and Bifidobacterium pseudolongum were higher in transition 1 milk. This study indicated that the bacterial composition in colostrum was more similar to that of transition 1 milk, whereas the bacterial community in transition 2 milk was similar to that of mature milk which suggests that bacterial composition in human breast milk shows stage-specific signatures even within a short period at both genus level and Bifidobacterium and Lactobacillus species levels, providing insights into probiotic supplementation for the nursing mother.

The intestinal microbiome and the role of probiotics/prebiotics in the therapeutic approach of atopic dermatitis: A review

Atopic dermatitis (AD) is the most common chronic inflammatory skin condition, characterized by multiple recurrent eczematous lesions and intense itchiness. It is a multifactorial skin disorder involving an association between genetic and environmental factors that lead to a defect of the epithelial barrier in conjunction with immunological dysregulation. Over the last decade, there has been an increasing understanding of the role of the human microbiota in preserving skin integrity and that a shift in the homeostasis of these microorganisms may lead to dysbiosis and disease. Diversity in the intestinal microbiome and its role in the etiopathogenesis of AD has been described and has become of great interest. In this report, we have reviewed the importance of the gut microbiome and the possible mechanism in the pathogenesis of AD as well as the therapeutic impact of probiotics and prebiotics

Probiotics: Protecting Our Health from the Gut

The gut microbiota (GM) comprises billions of microorganisms in the human gastrointestinal tract. This microbial community exerts numerous physiological functions. Prominent among these functions is the effect on host immunity through the uptake of nutrients that strengthen intestinal cells and cells involved in the immune response. The physiological functions of the GM are not limited to the gut, but bidirectional interactions between the gut microbiota and various extraintestinal organs have been identified. These interactions have been termed interorganic axes by several authors, among which the gut-brain, gut-skin, gut-lung, gut-heart, and gut-metabolism axes stand out. It has been shown that an organism is healthy or in homeostasis when the GM is in balance. However, altered GM or dysbiosis represents a critical factor in the pathogenesis of many local and systemic diseases. Therefore, probiotics intervene in this context, which, according to various published studies, allows balance to be maintained in the GM, leading to an individual's good health.

Probiotics for the prevention of atopic dermatitis in infants from different geographic regions: a systematic review and meta-analysis

BackgroundAtopic dermatitis (AD) is a common skin disease during infancy, but the preventive effect of probiotics on AD remains unclear.AimTo evaluate the efficacy of probiotic supplementation for the prevention of AD in infants.MethodsPubMed, Cochrane Library, and Embase databases were reviewed for relevant randomized controlled trials (RCTs). Two authors independently extracted the data. The primary endpoint was the risk of AD in infants. Risk ratio (RR) and 95% confidence interval (CI) were calculated.ResultsA total of 20 related articles including 22 studies were included. A significant reduction in AD risk was revealed for the probiotic group compared to the control group (RR 0.76; 95% CI 0.67-0.87). Subgroup analyses by participant receiving intervention revealed that not only probiotics given to mother (RR 0.70; 95% CI 0.57-0.85) or given to mother and infant (RR 0.76; 95% CI 0.61-0.95) were effective in preventing AD in infants, and probiotics given to infants alone (RR 0.76; 95% CI 0.60-0.96) still effectively decreased the risk of AD.ConclusionProbiotic supplementation reduced the risk of developing AD in infants. Furthermore, probiotic supplementation given to mother or to mother and infant could effectively prevent AD in infants.

Manipulating Microbiota to Treat Atopic Dermatitis: Functions and Therapies

Atopic dermatitis (AD) is a globally prevalent skin inflammation with a particular impact on children. Current therapies for AD are challenged by the limited armamentarium and the high heterogeneity of the disease. A novel promising therapeutic target for AD is the microbiota. Numerous studies have highlighted the involvement of the skin and gut microbiota in the pathogenesis of AD. The resident microbiota at these two epithelial tissues can modulate skin barrier functions and host immune responses, thus regulating AD progression. For example, the pathogenic roles of Staphylococcus aureus in the skin are well-established, making this bacterium an attractive target for AD treatment. Targeting the gut microbiota is another therapeutic strategy for AD. Multiple oral supplements with prebiotics, probiotics, postbiotics, and synbiotics have demonstrated promising efficacy in both AD prevention and treatment. In this review, we summarize the association of microbiota dysbiosis in both the skin and gut with AD, and the current knowledge of the functions of commensal microbiota in AD pathogenesis. Furthermore, we discuss the existing therapies in manipulating both the skin and gut commensal microbiota to prevent or treat AD. We also propose potential novel therapies based on the cutting-edge progress in this area.

Human Breast Milk: From Food to Active Immune Response With Disease Protection in Infants and Mothers

Breastfeeding is associated with long-term wellbeing including low risks of infectious diseases and non-communicable diseases such as asthma, cancer, autoimmune diseases and obesity during childhood. In recent years, important advances have been made in understanding the human breast milk (HBM) composition. Breast milk components such as, non-immune and immune cells and bioactive molecules, namely, cytokines/chemokines, lipids, hormones, and enzymes reportedly play many roles in breastfed newborns and in mothers, by diseases protection and shaping the immune system of the newborn. Bioactive components in HBM are also involved in tolerance and appropriate inflammatory response of breastfed infants if necessary. This review summarizes the current literature on the relationship between mother and her infant through breast milk with regard to disease protection. We will shed some light on the mechanisms underlying the roles of breast milk components in the maintenance of health of both child and mother.

The Maternal-Fetal Gut Microbiota Axis: Physiological Changes, Dietary Influence, and Modulation Possibilities

The prenatal period and the first years of life have a significant impact on the health issues and life quality of an individual. The appropriate development of the immune system and the central nervous system are thought to be major critical determining events. In parallel to these, establishing an early intestinal microbiota community is another important factor for future well-being interfering with prenatal and postnatal developmental processes. This review aims at summarizing the main characteristics of maternal gut microbiota and its possible transmission to the offspring, thereby affecting fetal and/or neonatal development and health. Since maternal dietary factors are potential modulators of the maternal-fetal microbiota axis, we will outline current knowledge on the impact of certain diets, nutritional factors, and nutritional modulators during pregnancy on offspring's microbiota and health.

The Effects of Probiotic Supplementation on Clinical Symptom, Weight Loss, Glycemic Control, Lipid and Hormonal Profiles, Biomarkers of Inflammation, and Oxidative Stress in Women with Polycystic Ovary Syndrome: a Systematic Review and Meta-analysis of Randomized Controlled Trials

The purpose of this systematic review and meta-analysis of randomized controlled trials (RCTs) is to determine the effectiveness of probiotic supplementation on clinical symptoms, weight loss, glycemic control, lipid and hormonal profiles, and biomarkers of inflammation and oxidative stress in women with polycystic ovary syndrome (PCOS). Eligible studies were systematically searched from Cochrane Library, Embase, Medline, and Web of Science databases until January 2019. Cochran (Q) and I-square statistics were used to measure heterogeneity among included studies. Data were pooled by using random-effect model and expressed as standardized mean difference (SMD) with 95% confidence interval (CI). Eleven articles were included in this meta-analysis. Probiotic supplementation significantly decreased weight (SMD - 0.30; 95% CI, - 0.53, - 0.07; P = 0.01), body mass index (BMI) (SMD - 0.29; 95% CI, - 0.54, - 0.03; P = 0.02), fasting plasma glucose (FPG) (SMD - 0.26; 95% CI, - 0.45, - 0.07; P < 0.001), insulin (SMD - 0.52; 95% CI, - 0.81, - 0.24; P < 0.001), homeostatic model assessment for insulin resistance (HOMA-IR) (SMD - 0.53; 95% CI, - 0.79, - 0.26; P < 0.001), triglycerides (SMD - 0.69; 95% CI, - 0.99, - 0.39; P < 0.001), VLDL-cholesterol (SMD - 0.69; 95% CI, - 0.99, - 0.39; P < 0.001), C-reactive protein (CRP) (SMD - 1.26; 95% CI, - 2.14, - 0.37; P < 0.001), malondialdehyde (MDA) (SMD - 0.90; 95% CI, - 1.16, - 0.63; P < 0.001), hirsutism (SMD - 0.58; 95% CI, - 1.01, - 0.16; P < 0.001), and total testosterone levels (SMD - 0.58; 95% CI, - 0.82, - 0.34; P < 0.001), and also increased the quantitative insulin sensitivity check index (QUICKI) (SMD 0.41; 95% CI, 0.11, 0.70; P < 0.01), nitric oxide (NO) (SMD 0.33; 95% CI 0.08, 0.59; P = 0.01), total antioxidant capacity (TAC) (SMD 0.64; 95% CI, 0.38, 0.90; P < 0.001), glutathione (GSH) (SMD 0.26; 95% CI, 0.01, 0.52; P = 0.04), and sex hormone binding globulin (SHBG) levels (SMD 0.46; 95% CI, 0.08, 0.85; P = 0.01). Probiotic supplementation may result in an improvement in weight, BMI, FPG, insulin, HOMA-IR, triglycerides, VLDL-cholesterol, CRP, MDA, hirsutism, total testosterone, QUICKI, NO, TAC, GSH, and SHBG but did not affect dehydroepiandrosterone sulfate levels, and total, LDL, and HDL cholesterol levels in patients with PCOS.

A. muciniphila Supplementation in Mice during Pregnancy and Lactation Affects the Maternal Intestinal Microenvironment

During pregnancy and lactation, considerable factors that affect the maternal microbiome are associated with the advancement of numerous diseases, which can potentially affect offspring health. Probiotics have shown potential for the maintenance of microbiota homeostasis of mothers in this period. The specific objective of this study was to investigate whether the application of Akkermansia muciniphila (A. muciniphila) during pregnancy and lactation impacts maternal and offspring health. Here we show that dams fed with A. muciniphila is safe, enhances the intestinal barrier and alters gut microbiota composition and diversity at the end of lactation, including the significant enrichment of A. muciniphila and Ruminococcus_1 in offspring from probiotic-fed dams. However, compared with the control group, the fecal metabolites of the A. muciniphila group only changed slightly. Additionally, A. muciniphila supplementation did not significantly increase the abundance of A. muciniphila in the fecal microbiota of offspring mice. Compared with the control group, the fecal metabolic profile of three-week-old offspring of mice fed with A. muciniphila were significantly changed, containing the D-glutamine and D-glutamate metabolism pathways. These results provided evidence that A. muciniphila supplementation in mice during pregnancy and lactation is safe and seemed to have a more beneficial effect on dams. In the future, using probiotics to regulate maternal microbiomes during pregnancy and lactation could be shown to have a more lasting and beneficial effect.

Microbiome Modulation as a Therapeutic Approach in Chronic Skin Diseases

There is a growing quantity of evidence on how skin and gut microbiome composition impacts the course of various dermatological diseases. The strategies involving the modulation of bacterial composition are increasingly in the focus of research attention. The aim of the present review was to analyze the literature available in PubMed (MEDLINE) and EMBASE databases on the topic of microbiome modulation in skin diseases. The effects and possible mechanisms of action of probiotics, prebiotics and synbiotics in dermatological conditions including atopic dermatitis (AD), psoriasis, chronic ulcers, seborrheic dermatitis, burns and acne were analyzed. Due to the very limited number of studies available regarding the topic of microbiome modulation in all skin diseases except for AD, the authors decided to also include case reports and original studies concerning oral administration and topical application of the pro-, pre- and synbiotics in the final analysis. The evaluated studies mostly reported significant health benefits to the patients or show promising results in animal or ex vivo studies. However, due to a limited amount of research and unambiguous results, the topic of microbiome modulation as a therapeutic approach in skin diseases still warrants further investigation.

Mechanisms of microbe-immune system dialogue within the skin

The prevalence and severity of dermatological conditions such as atopic dermatitis have increased dramatically during recent decades. Many of the factors associated with an altered risk of developing inflammatory skin disorders have also been shown to alter the composition and diversity of non-pathogenic microbial communities that inhabit the human host. While the most densely microbial populated organ is the gut, culture and non-culture-based technologies have revealed a dynamic community of bacteria, fungi, viruses and mites that exist on healthy human skin, which change during disease. In this review, we highlight some of the recent findings on the mechanisms through which microbes interact with each other on the skin and the signalling systems that mediate communication between the immune system and skin-associated microbes. In addition, we summarize the ongoing clinical studies that are targeting the microbiome in patients with skin disorders. While significant efforts are still required to decipher the mechanisms underpinning host-microbe communication relevant to skin health, it is likely that disease-related microbial communities, or Dermatypes, will help identify personalized treatments and appropriate microbial reconstitution strategies.

Novel Insights into the Role of Probiotics in Respiratory Infections, Allergies, Cancer, and Neurological Abnormalities

In recent years, probiotics have attracted public attention and transformed the social perception of microorganisms, convening a beneficial role/state on human health. With aging, the immune system, body physiology, and intestinal microbiota tend to change unfavorably, resulting in many chronic conditions. The immune-mediated disorders can be linked to intestinal dysbiosis, consequently leading to immune dysfunctions and a cluster of conditions such as asthma, autoimmune diseases, eczema, and various allergies. Probiotic bacteria such as Lactobacillus and Bifidobacterium species are considered probiotic species that have a great immunomodulatory and anti-allergic effect. Moreover, recent scientific and clinical data illustrate that probiotics can regulate the immune system, exert anti-viral and anti-tumoral activity, and shields the host against oxidative stress. Additionally, microbiota programming by probiotic bacteria can reduce and prevent the symptoms of respiratory infections and ameliorate the neurological status in humans. This review describes the most recent clinical findings, including safe probiotic therapies aiming to medicate respiratory infections, allergies, cancer, and neurological disorders due to their physiological interconnection. Subsequently, we will describe the major biological mechanism by which probiotic bacteriotherapy expresses its anti-viral, anti-allergic, anticancer, and neuro-stimulatory effects.

Comparative effectiveness of probiotic strains on the prevention of pediatric atopic dermatitis: A systematic review and network meta-analysis

BACKGROUND

Atopic dermatitis is the most common chronic skin disease affecting the pediatric population. Probiotics have been proposed to be effective in preventing the development of pediatric atopic dermatitis. Although studies show promise for the use of probiotics, the evidence is still inconclusive due to significant heterogeneity and imprecision.

OBJECTIVE

To determine the comparative effectiveness of the different types of probiotic strains in preventing the development of atopic dermatitis among pediatric patients.

METHODOLOGY

A systematic search of Cochrane Library, MEDLINE, TRIP Database, and Centre for Research and Dissemination was conducted. Manual search of the reference lists and search for unpublished articles were also done. All randomized controlled trials available from inception until April 12, 2020, on the use of probiotics in the prevention of atopic dermatitis among children were included. The comparator groups considered are other probiotic strains and placebo. The primary outcome of interest was the development of atopic dermatitis. Two authors independently searched for articles, screened the articles for inclusion, appraised the articles using the Cochrane risk of bias tool version 2, and extracted the data. In case of disagreement, the two authors discussed the source of disagreement until consensus was reached. If consensus was not reached, an independent third party reviewer was consulted. Frequentist network meta-analysis was conducted using STATA 14 software. The ranking probabilities and surface under the cumulative ranking curve (SUCRA) values were obtained to determine ranking of the different probiotic strains based on efficacy and safety data.

RESULTS

We included 21 original studies represented by 35 records and a total of 5406 children with atopic dermatitis as diagnosed by clinicians or fulfillment of validated diagnostic criteria. All studies were randomized placebo-controlled trials. The top 3 probiotic preparations in terms of efficacy in reducing the risk of atopic dermatitis are Mix8 (Lactobacillus paracasei ST11, Bifidobacterium longum BL999), LP (Lactobacillus paracasei ssp paracasei F19) and Mix3 (Lactobacillus rhamnosus GG, Bifidobacterium animalis ssp lactis Bb-12). Mix8 compared with placebo probably reduces the risk of atopic dermatitis based on low-quality evidence (RR = 0.46, 95% CI 0.25-0.85). Mix3 compared with placebo also probably reduces the risk of atopic dermatitis based on low-quality evidence (RR = 0.50, 95% CI 0.27-0.94). It is uncertain whether LP compared with placebo reduces the risk of atopic dermatitis due to very-low-quality certainty of evidence (RR = 0.49, 95% CI 0.20-1.19). In terms of adverse events, LGG may slightly lead to less adverse events compared with placebo based on low-quality evidence (RR = 0.70, 95% CI 0.32-1.52). Mix4 may slightly lead to more adverse events compared with placebo based on low-quality evidence (RR = 1.06, 95% CI 0.02-51.88). Based on subgroup analysis of studies involving infants, Mix3 compared with placebo probably reduces the risk of atopic dermatitis based on low-quality evidence (RR = 0.46, 95% CI 0.22-0.97). In the subgroup analysis of studies where probiotics were administered to pregnant women and to infants, LRH compared with placebo probably reduces the risk of atopic dermatitis based on moderate-quality evidence (RR = 0.54, 95% CI 0.26-1.11).

CONCLUSION

Certain probiotic preparations demonstrate efficacy in reducing the risk of developing atopic dermatitis when administered to pregnant women, infants, or both.

Colonization Ability and Impact on Human Gut Microbiota of Foodborne Microbes From Traditional or Probiotic-Added Fermented Foods: A Systematic Review

A large subset of fermented foods act as vehicles of live environmental microbes, which often contribute food quality assets to the overall diet, such as health-associated microbial metabolites. Foodborne microorganisms also carry the potential to interact with the human gut microbiome via the food chain. However, scientific results describing the microbial flow connecting such different microbiomes as well as their impact on human health, are still fragmented. The aim of this systematic review is to provide a knowledge-base about the scientific literature addressing the connection between foodborne and gut microbiomes, as well as to identify gaps where more research is needed to clarify and map gut microorganisms originating from fermented foods, either traditional or added with probiotics, their possible impact on human gut microbiota composition and to which extent foodborne microbes might be able to colonize the gut environment. An additional aim was also to highlight experimental approaches and study designs which could be better standardized to improve comparative analysis of published datasets. Overall, the results presented in this systematic review suggest that a complex interplay between food and gut microbiota is indeed occurring, although the possible mechanisms for this interaction, as well as how it can impact human health, still remain a puzzling picture. Further research employing standardized and trans-disciplinary approaches aimed at understanding how fermented foods can be tailored to positively influence human gut microbiota and, in turn, host health, are therefore of pivotal importance.

The prevention effect of probiotics against eczema in children: an update systematic review and meta-analysis

Accumulated evidences support the fetus's intestinal flora unbalance is associated with the development of allergic diseases. Probiotic supplements in pregnancy and childhood might prevent atopic diseases. The aim of this systematic review and meta-analysis was to evaluate the effect of probiotic supplementation during pregnancy and early infancy in preventing eczema, atopic eczema, and other allergic diseases. We also explored whether different probiotic strains or intervention objects affected the antiallergic effect of probiotics and the prevention atopy effect of the long-term period. Fixed-effect models were used, and random-effects models where significant heterogeneity was present. Results were expressed as odds ratios (ORs) with a 95% confidence interval (CI). Twenty-one studies were included in the meta-analysis. The probiotics group had a significantly lower risk of eczema and atopic eczema compared to controls, especially those treated with probiotic combinations. Mothers' probiotics intake significantly contributed to reducing the risk of eczema as well as atopic eczema. What's more, probiotics seemed effective on eczema prevention ≤2 years of age, but against atopic eczema after 1 of age year. No significant difference in terms of prevention of asthma, rhinitis, wheeze, allergic diseases and sensation. In brief, a probiotic supplement is expected to become a novel potential strategy for infant eczema and atopic eczema.

Can Mixed Strains of Lactobacillus and Bifidobacterium Reduce Eczema in Infants under Three Years of Age? A Meta-Analysis

(1) Background: Whether early supplementation of probiotics to improve intestinal flora can effectively prevent eczema remains a controversial issue. We aimed to investigate the effect of a mixed strain of Lactobacillus and Bifidobacterium on eczema in infants under three years old at present; (2) Methods: We searched the databases of PubMed, Web of Science, and Cochrane Library, as well as National Knowledge Infrastructure (CNKI), WeiPu (VIP), and WanFang Data (WanFang) for randomized controlled trials (RCTs) of probiotics in the prevention of eczema in infants without language restriction. The main outcome was eczema incidence, while adverse events during the intervention constituted the secondary outcome. The random-/fixed-effects model was utilized to calculate the combined relative risk (RR) and 95% confidence interval (CI). The methodological quality of the study was evaluated using the Cochrane "bias risk" tool. According to the initial intervention time, subgroup analysis was carried out, follow-up time, family history, etc.; (3) Results: Nine articles were selected (2093 infants). The Lactobacillus and Bifidobacterium mixed strain could prevent eczema in infants under three years of age compared to the placebo (RR = 0.60; I² = 67%; p < 0.001). Subgroup analysis revealed that the mixture of two probiotic strains had preventive effects on both infants with positive (RR = 0.53; I² = 52%; p < 0.001) and negative (RR = 0.69; I² = 62%; p = 0.02) family history; The follow-up time for ≤12 months (RR = 0.65; I² = 12%; p = 0.01) and 12-24 months (RR = 0.60; I² = 79%; p = 0.003), daily dose of probiotics ≤ 1 × 10⁹ and > 1 × 10⁹ colony forming units all can be effective (p < 0.01); Compared with the intervention of infants alone (RR = 0.63; I² = 63%; p = 0.29), the effect of probiotics mixture at the beginning of pregnancy was more significant (RR = 0.59; I² = 71%; p < 0.001); Except for the mixture of Lactobacillus rhamnosusGG (LGG) and Bifidobacterium longum (B. longum) (p = 0.18), other subgroups of intervention group can play a preventive effect (p < 0.05); (4) Conclusions: The mixed strain of Lactobacillus and Bifidobacterium can effectively reduce the incidence of eczema in infants under three years old. However, further research is needed to fully understand the exact mechanism of their effect on infant eczema.

Probiotics as a Possible Strategy for the Prevention and Treatment of Allergies. A Narrative Review

Allergies are an increasing global public health concern, especially for children and people living in urban environments. Allergies impair the quality of life of those who suffer from them, and for this reason, alternatives for the treatment of allergic diseases or reduction in their symptoms are being sought. The main objective of this study was to compile the studies carried out on probiotics as a possible therapy for allergies. The most studied allergies on which probiotics have been shown to have a beneficial effect are rhinitis, asthma, and atopic dermatitis. Most studies have studied the administration of Lactobacillus and Bifidobacterium spp. in children and have shown beneficial effects, such as a reduction in hyperreactivity and inflammation caused by allergens and a decrease in cytokine release, among other beneficial effects. In the case of children, no clear beneficial effects were found in several studies, and the potential risk from the use of some opportunistic bacteria, such as probiotics, seems controversial. In the studies that reported beneficial results, these effects were found to make allergy symptoms less aggressive, thus reducing morbidity in allergy sufferers. The different effects of the same probiotic bacteria on different patients seem to reinforce the idea that the efficacy of probiotics is dependent on the microbial species or strain, its derived metabolites and byproducts, and the gut microbiota eubiosis of the patient. This study is relevant in the context of allergic diseases, as it provides a broader understanding of new alternatives for the treatment of allergies, both in children, who are the main sufferers, and adults, showing that probiotics, in some cases, reduce the symptoms and severity of such diseases.

Reporting of Perinatal Outcomes in Probiotic Randomized Controlled Trials. A Systematic Review and Meta-Analysis

The use of probiotic microorganisms in clinical practice has increased in recent years and a significant number of pregnant women are regular consumers of these products. However, probiotics might modulate the immune system, and whether or not this modulation is beneficial for perinatal outcomes is unclear. We performed a systematic review and meta-analysis to evaluate the reporting of perinatal outcomes in randomized controlled trials including women supplemented with probiotic microorganisms during pregnancy. We also analyzed the effects that the administration of probiotic microorganisms exerts on perinatal outcomes. In the review, 46 papers were included and 25 were meta-analyzed. Reporting of perinatal outcomes was highly inconsistent across the studies. Only birth weight, cesarean section, and weeks of gestation were reported in more than 50% of the studies. Random effects meta-analysis results showed that the administration of probiotic microorganisms during pregnancy did not have any a positive or negative impact on the perinatal outcomes evaluated. Subgroup analysis results at the strain level were not significantly different from main analysis results. The administration of probiotic microorganisms does not appear to influence perinatal outcomes. Nonetheless, future probiotic studies conducted in pregnant women should report probiotic strains and perinatal outcomes in order to shed light upon probiotics' effects on pregnancy outcomes.

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.

Protecting the outside: biological tools to manipulate the skin microbiota

Interest surrounding the role that skin microbes play in various aspects of human health has recently experienced a timely surge, particularly among researchers, clinicians and consumer-focused industries. The world is now approaching a post-antibiotic era where conventional antibacterial therapeutics have shown a loss in effectiveness due to overuse, leading to the looming antibiotic resistance crisis. The increasing threat posed by antibiotic resistance is compounded by an inadequate discovery rate of new antibiotics and has, in turn, resulted in global interest for alternative solutions. Recent studies have demonstrated that imbalances in skin microbiota are associated with assorted skin diseases and infections. Specifically, restoration of this ecosystem imbalance results in an alleviation of symptoms, achieved simply by applying bacteria normally found in abundance on healthy skin to the skin of those deficient in beneficial bacteria. The aim of this review is to discuss the currently available literature on biological tools that have the potential to manipulate the skin microbiota, with particular focus on bacteriocins, phage therapy, antibiotics, probiotics and targets of the gut-skin axis. This review will also address how the skin microbiota protects humans from invading pathogens in the external environment while discussing novel strategies to manipulate the skin microbiota to avoid and/or treat various disease states.

Anti-Cancer Effects of Probiotic Lactobacillus acidophilus for Colorectal Cancer Cell Line Caco-2 through Apoptosis Induction

Background: Colorectal cancer is one of the most common cancers worldwide. Probiotics are useful and non-pathogenic microorganisms in the gastrointestinal tract, which can show anticancer activity through the induction of apoptosis. This study aimed to evaluate the antiproliferative effects of Lactobacillus acidophilus probiotic on the Caco-2 colorectal cancer cell line. Methods: The supernatant (secreted metabolites) and bacterial extract of L. acidophilus probiotics were prepared and used as an anti-proliferative agent on the colorectal cancer cell line, Caco-2 in vitro. The effects of supernatant and extract of L. acidophilus were evaluated on the viability and proliferation of cancer cells using MTT assay. Moreover, morphological alterations of cancer cells treated with supernatant and extract of L. acidophilus were evaluated by an inverted phase contrast microscope. The mRNA expression levels of apoptosis-related genes (SURVIVIN and SMAC) in treated cancer cells and untreated controls were evaluated using the Real-Time PCR method. Results: The results showed that the supernatant and extract of L. acidophilus inhibited the viability and proliferation of cancer cells in a dose and time-dependent manner. Moreover, various morphological alterations were observed in the treated cancer cells, which are indicators of apoptosis induction. The mRNA expression of SURVIVIN and SMAC genes were significantly up-regulated and downregulated in the treated cancer cells, respectively. Conclusion: The results of the present study suggested that the supernatant and extract of L.acidophilus could inhibit the viability and proliferation of colorectal cancer cell line, Caco-2through induction of apoptosis, increase the survival rate of colon cancer patients.

The Role of Probiotics in the Prevention and Treatment of Atopic Dermatitis in Children: An Updated Systematic Review and Meta-Analysis of Randomized Controlled Trials

BACKGROUND

Atopic dermatitis (AD) is a chronic inflammatory skin disease common among infants and children. It is associated with a high risk of allergies, asthma, and mental health problems. Attempts have been made to use probiotics in clinical interventions for AD.

OBJECTIVE

Our objective was to perform an updated meta-analysis of recently published studies to evaluate the effect of probiotics in the prevention and treatment of AD in children and to further understand the role of probiotics in AD interventions in the clinic.

METHOD

We searched the PubMed/MEDLINE, Embase, Cochrane Central Register of Controlled Trials, China National Knowledge Infrastructure, and Wanfang databases with prespecified selection criteria from inception of each database to 11 January 2020. No language restrictions were applied.

RESULTS

A total of 25 studies were included in our meta-analysis. Of these, 14 were prevention studies (with 3049 children enrolled) and 11 were treatment studies (with 816 children enrolled). One treatment study was excluded after the sensitivity analysis. From the 14 prevention studies included, the pooled relative risk ratio of AD in those treated with probiotics versus placebo was 0.70 [95% confidence interval (CI) 0.57-0.84; P = 0.0002]. Subgroup analyses showed that only mixed strains of probiotics had a significant effect on lowering the incidence of AD. Probiotics administered solely to infants did not prevent the development of AD, but effects were significant when probiotics were administered to both pregnant mothers and their infants or solely to pregnant mothers. In studies with treatment durations > 6 months, the incidence of AD decreased significantly; a similar effect was achieved when the treatment duration was < 6 months. Meta-analysis of the ten treatment studies showed a significant decrease in the weighted mean difference (WMD) in Scoring Atopic Dermatitis (SCORAD) index values in the probiotics group compared with the control group (WMD, - 7.23; 95% CI - 10.59 to - 3.88; P < 0.0001). Subgroup analyses showed that both single-strain and mixed-strain probiotics had a significant effect on improving SCORAD values. Studies with participants aged < 1 year (P = 0.07) reported no significant results. In studies with treatment periods > 8 weeks, SCORAD values seemed to decrease more than in studies with treatment periods < 8 weeks. However, the subgroup difference was only statistically significant when the analysis was performed according to participant age in prevention studies.

CONCLUSION

Our updated meta-analysis demonstrates that interventions with probiotics potentially lower the incidence of AD and relieve AD symptoms in children, particularly when treating infants and children aged ≥ 1 year with AD. Interventions with mixed-strain probiotics tended to have better preventive and curative effects. Probiotics administered solely to infants appeared to produce negative preventive effects. Different intervention durations might also affect clinical outcomes. However, given the insignificant subgroup differences, except for treatment by participant age, and the moderate heterogeneity among the studies, these conclusions should be interpreted with caution, and more powerful randomized controlled trials using standardized measurements should be conducted to assess the long-term effects of probiotics.

Probiotic Supplementation During the Perinatal and Infant Period: Effects on Gut Dysbiosis and Disease

The perinatal period is crucial to the establishment of lifelong gut microbiota. The abundance and composition of microbiota can be altered by several factors such as preterm delivery, formula feeding, infections, antibiotic treatment, and lifestyle during pregnancy. Gut dysbiosis affects the development of innate and adaptive immune responses and resistance to pathogens, promoting atopic diseases, food sensitization, and infections such as necrotizing enterocolitis (NEC). Recent studies have indicated that the gut microbiota imbalance can be restored after a single or multi-strain probiotic supplementation, especially mixtures of Lactobacillus and Bifidobacterium strains. Following the systematic search methodology, the current review addresses the importance of probiotics as a preventive or therapeutic tool for dysbiosis produced during the perinatal and infant period. We also discuss the safety of the use of probiotics in pregnant women, preterm neonates, or infants for the treatment of atopic diseases and infections.

Pediococcus acidilactici intake decreases the clinical severity of atopic dermatitis along with increasing mucin production and improving the gut microbiome in Nc/Nga mice

Atopic dermatitis (AD) is a chronic inflammatory skin disease that is associated with intestinal microflora. Since specific probiotics may have better efficacy for AD, we determined the efficacy of Pediococcus acidilactici SRCM102024 (PA) for treating AD in HaCaT cells and NC/Nga mice and explored the mechanism of action. AD-like pathology was induced in HaCaT cells and the dorsal skin of Nc/Nga mice by local exposure to 2,4-dinitrochlorobenzene (DNCB). In AD-lesion induced mice, PA in low-, medium- and high-dosages (5 × 10E6, 5 × 10E7 and 5 × 10E8 CFU/kg bw, respectively) and dexamethasone (3 mg/kg bw, positive-control) were orally administered for 5 weeks. The clinical AD severity, serum immunoglobulin E (IgE) and TNF-α, gene expressions of interleukin (IL)-4, IL-13, and TNF-α and gut microflora were measured. PA treatment (100-300 CFU/mL) dose-dependently increased cell survival in DNCB-induced HACAT cells. PA reduced the relative mRNA expression of PAR-2, TNF-α, IL-4 and IL-13 in the cells. In dorsal skin of Nc/Nga mice applied with DNCB, PA dose-dependently attenuated erythema, hemorrhage, edema, excoriation, dryness and scratching behavior and PA-H improved the clinical symptoms similar to the positive-control. PA-M and PA-H treatment significantly prevented the disturbance of the dorsal skin tissues and decreased the inflammatory cellular infiltrate of mast cells, compared to the control. PA dose-dependently reduced serum IgE and TNF-α concentrations and the mRNA expression of TNF-α, IL-4, and IL-13 in dorsal skin. In gut microflora, relative counts of Lactobacillales, Butyricicoccus and Ruminococcus were decreased in the AD-control compared to the positive-control and the PA-M and PA-H prevented their decrease. However, the positive-control increased serum AST and ALT activities, indicating liver damage as an adverse effect. In conclusion, oral treatment of PA (human equivalent 1 × 10E9-1 × 10E10) relieved the AD symptoms by dose-dependently preventing over-activation of the immune response. Oral PA intake may be a safe and effective alternative therapy for AD.

Variations in early gut microbiome are associated with childhood eczema

We assessed the relationship between gut microbiome profile and childhood eczema in 172 subjects (age < 3 years, healthy group N = 123, eczema group N = 49) utilizing 16S rRNA gene sequencing. Lower relative abundance of Bifidobacterium was shown to be associated with childhood eczema. Considering that developmental and environmental factors could modify the state of children's gut microbiome, we divided the samples into four age groups: 0-0.5 years, 0.5-1 years, 1-2 years and 2-3 years for farther analyses. Data revealed significant inter-group differences between healthy and eczema samples in all age groups, and decreased microbial diversity was most significantly found in children with eczema of age 2-3 years old. Decreased abundance of Bifidobacterium was a major finding in eczema groups from 0.5-3 years compared to the age matched healthy controls, but not significant in children younger than 6 month old. Of note, Bifidobacterium operational taxonomic units were identified by Random Forest with highly predictive power of 0.83 (AUC = 0.83) in ROC analysis, which also confirmed its role as a key genus that is associated with eczema. To verify the sequencing results, we performed quantitative polymerase chain reaction of Bifidobacterium and Bacteroides in the same cohort, and in a new eczema cohort (N = 57) for validation. Significantly, lower Bifidobacterium quantities were found in both eczema groups with an age range of 0.5-3 years. These results suggest variations in early gut microbiome are associated with childhood eczema.

Commensal Obligate Anaerobic Bacteria and Health: Production, Storage, and Delivery Strategies

In the last years several human commensals have emerged from the gut microbiota studies as potential probiotics or therapeutic agents. Strains of human gut inhabitants such as Akkermansia, Bacteroides, or Faecalibacterium have shown several interesting bioactivities and are thus currently being considered as food supplements or as live biotherapeutics, as is already the case with other human commensals such as bifidobacteria. The large-scale use of these bacteria will pose many challenges and drawbacks mainly because they are quite sensitive to oxygen and/or very difficult to cultivate. This review highlights the properties of some of the most promising human commensals bacteria and summarizes the most up-to-date knowledge on their potential health effects. A comprehensive outlook on the potential strategies currently employed and/or available to produce, stabilize, and deliver these microorganisms is also presented.

Classical methods and perspectives for manipulating the human gut microbial ecosystem

A healthy Human Gut Microbial Ecosystem (HGME) is a necessary condition for maintaining the orderly function of the whole body. Major alterations in the normal gut microbial composition, activity and functionality (dysbiosis) by an environmental or host-related disruptive event, can compromise metabolic, inflammatory, and neurological processes, causing disorders such as obesity, inflammatory bowel disease, colorectal cancer, and depressive episodes. The restore or the maintaining of the homeostatic balance of Gut Microbiota (GM) populations (eubiosis) is possible through diet, the use of probiotics, prebiotics, antibiotics, and even Fecal Microbiota Transplantation (FMT). Although these "classic methods" represent an effective and accepted way to modulate GM, the complexity of HGME requires new approaches to control it in a more appropriate way. Among the most promising emergent strategies for modulating GM are the use of engineered nanomaterials (metallic nanoparticles (NP), polymeric-NP, quantum dots, micelles, dendrimers, and liposomes); phagotherapy (i.e., phages linked with the CRISPR/Cas9 system), and the use of antimicrobial peptides, non-antibiotic drugs, vaccines, and immunoglobulins. Here we review the current state of development, implications, advantages, disadvantages, and perspectives of the different approaches for manipulating HGME.

Supporting a Healthy Microbiome for the Primary Prevention of Eczema

Eczema is increasing worldwide with associated increases in health costs and decreases in quality of life. There are many factors that are speculated to interact in the development of eczema including genetics and environmental exposures. Prevention of the development of eczema may prevent the further development of food allergies and asthma. This concept has prompted a variety of research into the area of primary prevention of eczema in infants. This exploration includes a growing body of research examining infants supplemented with probiotics, prebiotics, or both (synbiotics) often compared with their breastfed counterparts. The goal of this paper is to examine the evidence for manipulating the microbiome in the prevention of eczema. Several strains of probiotics, compositions of prebiotics, and varied combinations of both are commercially available. Evidence supports altering the microbiome in infants at high risk of atopy who are not able to breastfeed with Lactobacillus strains when given both prenatally followed by prolonged use (greater than 6 months) postnatally for the primary prevention of eczema. Prebiotics have also been shown beneficial for primary prevention of eczema in formula-fed infants with prolonged use greater than 6 months. These findings are in keeping with the World Allergy Organization (WAO) recommendations that support interventions to manipulate the microbiome with both probiotics and prebiotics.

Effects of probiotics in the treatment of food hypersensitivity in children: a systematic review

INTRODUCTION

Food allergy is considered a public health problem for children. The modulation of the intestinal microbiota seems a promising strategy for the control of allergic reactions.

OBJECTIVE

To describe the effects of different forms of probiotics in pediatric food hypersensitivity treatment.

DATA SOURCE

We conducted a systematic review based on clinical trials published in the PubMed and Web of Science databases. The searches were carried out using the MeSH terms "Food Hypersensitivity," "Probiotics," "Lactobacillus," and "Bifidobacterium".

DATA SYNTHESIS

The final selection resulted in 18 clinical trials, which were predominantly samples of infants and pre-school children. The most-often used strain, either alone or in combination, was Lactobacillus rhamnosus GG; a placebo was mainly used in the control group. As for the vehicle, the most common forms were capsules and infant formulas, and the period of intervention ranged from four weeks to 24 months, with weekly or monthly visits to measure the outcomes. In these 18 trials, 46 analyses were performed with 27 different types of outcomes to evaluate the effects of probiotics (12 laboratory and 15 clinical). Twenty-seven of these analyses demonstrated the benefits of using these microorganisms. The SCORAD (atopic dermatitis index) and IgE levels and cytokines were the outcomes mostly evaluated.

CONCLUSION

The use of probiotics is beneficial in promoting immunomodulation and reducing clinical symptoms. However, more methodologically based research is needed to clarify the effect from each type, dose, and time of using them for the establishment of definitive care protocols.

The Role of Prebiotics and Probiotics in Prevention of Allergic Diseases in Infants

Allergic diseases have been linked to genetic and/or environmental factors, such as antibiotic use, westernized high fat and low fiber diet, which lead to early intestinal dysbiosis, and account for the rise in allergy prevalence, especially in western countries. Allergic diseases have shown reduced microbial diversity, including fewer lactobacilli and bifidobacteria, within the neonatal microbiota, before the onset of atopic diseases. Raised interest in microbiota manipulating strategies to restore the microbial balance for atopic disease prevention, through prebiotics, probiotics, or synbiotics supplementation, has been reported. We reviewed and discussed the role of prebiotics and/or probiotics supplementation for allergy prevention in infants. We searched PubMed and the Cochrane Database using keywords relating to "allergy" OR "allergic disorders," "prevention" AND "prebiotics" OR "probiotics" OR "synbiotics." We limited our evaluation to papers of English language including children aged 0-2 years old. Different products or strains used, different period of intervention, duration of supplementation, has hampered the draw of definitive conclusions on the clinical impact of probiotics and/or prebiotics for prevention of allergic diseases in infants, except for atopic dermatitis in infants at high-risk. This preventive effect on eczema in high-risk infants is supported by clear evidence for probiotics but only moderate evidence for prebiotic supplementation. However, the optimal prebiotic or strain of probiotic, dose, duration, and timing of intervention remains uncertain. Particularly, a combined pre- and post-natal intervention appeared of stronger benefit, although the definition of the optimal intervention starting time during gestation, the timing, and duration in the post-natal period, as well as the best target population, are still an unmet need.