Lactobacillus GG treatment during pregnancy for the prevention of eczema: a randomized controlled trial

The effect of oral probiotics in the last trimester on the human milk and infant gut microbiotas at six months postpartum: A randomized controlled trial

Objective

The main aim of this study was to evaluate the effect of oral probiotics on the human milk microbiota and determine whether that influenced infant microbiota development.

Methods

A total of 27 pregnant women were recruited; 14 were assigned to the probiotic group, and the rest were assigned to the control group. Their infants were likewise assigned to the probiotic group or the control group. Pregnant women in the probiotic group received probiotic supplementation from 32 weeks of gestation until delivery. Human milk samples and infant fecal samples were collected at 6 months after delivery, and 16S rRNA sequencing was used to analyze the composition of the human milk and infant gut microbiota (NCT06241222).

Results

In the control group, bacterial microbiota were detected in 8 out of 13 milk samples, whereas in the probiotic group, only 6 out of 14 milk samples contained bacterial microbiota. We examined the composition of the human milk and infant gut microbiota in both the control and probiotic groups. Spearman correlation analysis revealed that various genera in human milk were correlated with the infant gut microbiota. The Linear discriminant analysis effect size (LEfSe) showed that 6 bacteria in the human milk microbiota in the control group were significantly more abundant than those in the probiotic group. Nine bacteria were significantly more abundant in the human milk microbiota in the probiotic group than the control group. According to the LEfSe results, 11 bacteria in the infant gut microbiota in the control group were significantly more abundant than those in the probiotic group. Fourteen bacteria were significantly more abundant in the infant gut microbiota in the probiotic group than in the control group.

Conclusion

The infant gut microbiota at 6 months has a complicated relationship with the maternal human milk microbiota. Oral probiotic supplementation can change the composition of the human milk microbiota and the infant gut microbiota.

Effect of maternal prebiotic supplementation on human milk immunological composition: Insights from the SYMBA study

BACKGROUND

Immunomodulatory proteins in human milk (HM) can shape infant immune development. However, strategies to modulate their levels are currently unknown. This study investigated whether maternal prebiotic supplementation alters the levels of immunomodulatory proteins in HM.

METHODS

The study was nested within the SYMBA double-blind randomized controlled trial (ACTRN12615001075572), which investigated the effects of maternal prebiotic (short-chain galacto-oligosaccharides/long-chain fructo-oligosaccharides) supplementation from <21 weeks gestation during pregnancy until 6 months postnatal during lactation on child allergic disease risk. Mother-child dyads receiving prebiotics (n = 46) or placebo (n = 54) were included in this study. We measured the levels of 24 immunomodulatory proteins in HM collected at 2, 4, and 6 months.

RESULTS

Cluster analysis showed that the overall immunomodulatory protein composition of milk samples from both groups was similar. At 2 months, HM of prebiotic-supplemented women had decreased levels of TGF-β1 and TSLP (95% CI: -17.4 [-29.68, -2.28] and -57.32 [-94.22, -4.7] respectively) and increased levels of sCD14 (95% CI: 1.81 [0.17, 3.71]), when compared to the placebo group. At 4 months, IgG1 was lower in the prebiotic group (95% CI: -1.55 [-3.55, -0.12]) compared to placebo group.

CONCLUSION

This exploratory study shows that prebiotic consumption by lactating mothers selectively alters specific immunomodulatory proteins in HM. This finding is crucial for understanding how prebiotic dietary recommendations for pregnant and lactating women can modify the immune properties of HM and potentially influence infant health outcomes through immune support from breastfeeding.

How to Prevent Atopic Dermatitis (Eczema) in 2024: Theory and Evidence

Atopic dermatitis (AD) or eczema is a chronic inflammatory skin disease characterized by dry, itchy, and inflamed skin. We review emerging concepts and clinical evidence addressing the pathogenesis and prevention of AD. We examine several interventions ranging from skin barrier enhancement strategies to probiotics, prebiotics, and synbiotics; and conversely, from antimicrobial exposure to vitamin D and omega fatty acid supplementation; breastfeeding and hydrolyzed formula; and house dust mite avoidance and immunotherapy. We appraise the available evidence base within the context of the Grades of Recommendation, Assessment, Development, and Evaluation approach. We also contextualize our findings in relation to concepts relating AD and individual-patient allergic life trajectories versus a linear concept of the atopic march and provide insights into future knowledge gaps and clinical trial design considerations that must be addressed in forthcoming research. Finally, we provide implementation considerations to detect population-level differences in AD risk. Major international efforts are required to provide definitive evidence regarding what works and what does not for preventing AD.

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.

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.

Probiotics in Infancy and Childhood for Food Allergy Prevention and Treatment

Food allergy represents a failure of oral tolerance mechanisms to dietary antigens. Over the past few years, food allergies have become a growing public health problem worldwide. Gut microbiota is believed to have a significant impact on oral tolerance to food antigens and in initiation and maintenance of food allergies. Therefore, probiotics have also been proposed in this field as a possible strategy for modulating both the gut microbiota and the immune system. In recent years, results from preclinical and clinical studies suggest a promising role for probiotics in food allergy prevention and treatment. However, future studies are needed to better understand the mechanisms of action of probiotics in food allergies and to design comparable study protocols using specific probiotic strains, defined doses and exposure times, and longer follow-up periods.

Mucosal IgA immune complex induces immunomodulatory responses in allergic airway and intestinal TH2 disease

BACKGROUND

IgA is the most abundant immunoglobulin at the mucosal surface and although its role in regulating mucosal immunity is not fully understood, its presence is associated with protection from developing allergic disease.

OBJECTIVE

We sought to determine the role of IgA immune complexes for therapeutic application to mucosal allergic responses.

METHODS

Trinitrophenol (TNP)-specific IgA immune complexes were applied, using TNP-coupled ovalbumin (OVA), to airway and gut mucosal surfaces in systemically sensitized allergic animals to regulate allergen challenge responses. Animals were assessed for both pathologic and immune-mediated responses in the lung and gut, respectively, using established mouse models.

RESULTS

The mucosal application of IgA immune complexes in the lung and gut with TNP-OVA regulated TH2-driven allergic response in the lung and gut, reducing TH2 cytokines and mucus (lung) as well as diarrhea and temperature loss (gut), but increasing IL-10 and the number of regulatory T cells. The IgA-OVA immune complex did not alter peanut-induced anaphylaxis, indicating antigen specificity. Using OVA-specific DO.11-green fluorescent protein IL-4 reporter mouse-derived TH2-skewed cells in a transfer model demonstrated that mucosal IgA immune complex treatment reduced TH2-cell expansion and increased the number of regulatory T cells. To address a potential mechanism of action, TGF-β and IL-10 were induced in bone marrow-derived dendritic cells when they were exposed to IgA immune complex, suggesting a regulatory phenotype induced in dendritic cells that also led to an altered primary T-cell-mediated response in in vitro OVA-specific assays.

CONCLUSIONS

These studies highlight one possible mechanism of how allergen-specific IgA may provide a regulatory signal to reduce the development of allergic responses in the lung and gut.

Comparison of 30 Cytokines in Human Breast Milk between 1989 and 2013 in Japan

Milk cytokines play a vital role in mucosal immunity during infancy by supporting immune development and functions. Although the maternal background characteristics influence milk cytokines, changes in cytokine levels across generations remain unclear. Colostrum (C, n = 48) and mature milk (MM, n = 49) samples were collected from lactating Japanese women in 1989 (2727 samples) and 2013 (1408 samples). Milk cytokines were comprehensively measured using a suspension array and immunosorbent assays. The positive rates and cytokine concentrations were compared between the two generations using logistic and multiple regression analyses. Twenty-eight cytokines tested positive in all sample groups (1989-C, 1989-MM, 2013-C, and 2013-MM). The median osteopontin (OPN) level was significantly higher in the 1989-C group than in the 2013-C group (318.1 vs. 137.5 μg/mL; p = 0.0016) but did not differ between the MM groups. The median TGF-β1 level was significantly lower in the 1989-MM group than in the 2013-MM group (1056.2 vs. 1330.8 pg/mL; p = 0.008) but did not differ between the C groups. Most cytokines were comparable between generations, except for potential variation in the C-OPN and TGF-β1 levels. Milk cytokine secretion may reflect temporal changes in maternal background characteristics; however, the results from the analysis of 30-year-old samples may have influenced the milk cytokine levels. Further studies are needed with a larger number of milk samples collected from the same individuals at multiple time points over a wide lactation period, with detailed data on the maternal and infant background characteristics and diets.

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.

The Intestinal and Skin Microbiome in Patients with Atopic Dermatitis and Their Influence on the Course of the Disease: A Literature Review

Bacteria inhabiting the digestive tract are responsible for our health. The microbiome is essential for the development of the immune system and homeostasis of the body. Maintaining homeostasis is very important, but also extremely complicated. The gut microbiome is related to the skin microbiome. It can therefore be assumed that changes in the microbes inhabiting the skin are greatly influenced by the bacteria living in the intestines. Changes in the composition and function of microbes (dysbiosis in the skin and intestines) have recently been linked to changes in the immune response and the development of skin diseases, including atopic dermatitis (AD). This review was compiled by collaborating Dermatologists specializing in atopic dermatitis and psoriasis. A comprehensive review of the current literature was performed using PubMed and limited to relevant case reports and original papers on the skin microbiome in atopic dermatitis. The inclusion criterion was that the paper was published in a peer-reviewed journal in the last 10 years (2012-2022). No limitations on the language of the publication or the type of study were made. It has been shown that any rapid changes in the composition of the microflora may be associated with the appearance of clinical signs and symptoms of the disease. Various studies have proven that the microbiome of many systems (including the intestines) may have a significant impact on the development of the inflammatory process within the skin in the course of AD. It has been shown that an early interaction between the microbiome and immune system may result in a noticeable delay in the onset of atopic diseases. It seems to be of high importance for physicians to understand the role of the microbiome in AD, not only from the pathophysiological standpoint but also in terms of the complex treatment that is required. Perhaps young children diagnosed with AD present specific characteristics of the intestinal microflora. This might be related to the early introduction of antibiotics and dietary manipulations in breastfeeding mothers in the early childhood of AD patients. It is most likely related to the abuse of antibiotics from the first days of life.

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.

Effect of a Novel E3 Probiotics Formula on the Gut Microbiome in Atopic Dermatitis Patients: A Pilot Study

Atopic dermatitis (AD) has been shown to be closely related to gut dysbiosis mediated through the gut−skin axis, and thus the gut microbiome has recently been explored as a potential therapeutic target for the treatment of AD. Contrasting and varying efficacy have been reported since then. In order to investigate the determining factor of probiotics responsiveness in individuals with AD, we initiated the analysis of 41 AD patients with varying disease severity in Hong Kong, whereas the severity was assessed by Eczema Area and Severity Index (EASI) by board certified dermatologist. 16S rRNA sequencing on the fecal samples from AD patients were performed to obtain the metagenomics profile at baseline and after 8 weeks of oral administration of a novel E3 probiotics formula (including prebiotics, probiotics and postbiotics). While EASI of the participants were significantly lower after the probiotics treatment (p < 0.001, paired Wilcoxon signed rank), subjects with mild AD were found to be more likely to respond to the probiotics treatment. Species richness among responders regardless of disease severity were significantly increased (p < 0.001, paired Wilcoxon signed rank). Responders exhibited (1) elevated relative abundance of Clostridium, Fecalibacterium, Lactobacillus, Romboutsia, and Streptococcus, (2) reduced relative abundance of Collinsella, Bifidobacterium, Fusicatenibacter, and Escherichia-Shigella amid orally-intake probiotics identified using the machine learning algorithm and (3) gut microbiome composition and structure resembling healthy subjects after probiotics treatment. Here, we presented the gut microbiome dynamics in AD patients after the administration of the E3 probiotics formula and delineated the unique gut microbiome signatures in individuals with AD who were responding to the probiotics. These findings could guide the future development of probiotics use for AD management.

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.

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.

Effects of Probiotic Intervention on Markers of Inflammation and Health Outcomes in Women of Reproductive Age and Their Children

The human intestinal microbiota has been shown to be modulated during inflammatory conditions. Probiotic administration has been shown to affect the immune system and cytokine expression which can affect inflammation and health outcomes. There seems to be an association between the mother's intestinal microbiota and inflammation biomarkers, both of which may contribute to newborn early life immune and metabolic programming and impact short and long-term health outcomes. Probiotic supplementation during pregnancy has been shown to influence metabolic health, immunity, and gastrointestinal health of the mother, and can also have carry-over benefits to infants such as infant allergy risk reduction. Therefore, this review focuses on the evidence of probiotic administration in women of reproductive age, including during pregnancy and its impact on inflammatory markers and on maternal and infant health. We performed a PubMed search for articles published in English in the last 20 years. Immune markers were narrowed to serum and breast milk levels of TNF-α, IL-6 and TGF-β, IgA, and IL-10. Studies that investigated the beneficial effects of interventions in women with gestational diabetes mellitus, polycystic ovarian syndrome, and infant allergy management are summarized. These results show a beneficial or neutral effect on selected health outcomes and that it is safe for woman and their infants. The effect of probiotics on modulation of inflammatory markers was probiotic specific. More research is needed to further our understanding of the mechanisms underlying the effects of probiotics on inflammation and how these effects improve health outcomes.

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.

Microbial Dysbiosis Tunes the Immune Response Towards Allergic Disease Outcomes

The hygiene hypothesis has been popularized as an explanation for the rapid increase in allergic disease observed over the past 50 years. Subsequent epidemiological studies have described the protective effects that in utero and early life exposures to an environment high in microbial diversity have in conferring protective benefits against the development of allergic diseases. The rapid advancement in next generation sequencing technology has allowed for analysis of the diverse nature of microbial communities present in the barrier organs and a determination of their role in the induction of allergic disease. Here, we discuss the recent literature describing how colonization of barrier organs during early life by the microbiota influences the development of the adaptive immune system. In parallel, mechanistic studies have delivered insight into the pathogenesis of disease, by demonstrating the comparative effects of protective T regulatory (Treg) cells, with inflammatory T helper 2 (Th2) cells in the development of immune tolerance or induction of an allergic response. More recently, a significant advancement in our understanding into how interactions between the adaptive immune system and microbially derived factors play a central role in the development of allergic disease has emerged. Providing a deeper understanding of the symbiotic relationship between our microbiome and immune system, which explains key observations made by the hygiene hypothesis. By studying how perturbations that drive dysbiosis of the microbiome can cause allergic disease, we stand to benefit by delineating the protective versus pathogenic aspects of human interactions with our microbial companions, allowing us to better harness the use of microbial agents in the design of novel prophylactic and therapeutic strategies.

Biotechnological Processes Simulating the Natural Fermentation Process of Bee Bread and Therapeutic Properties-An Overview

Recent signs of progress in functional foods and nutraceuticals highlighted the favorable impact of bioactive molecules on human health and longevity. As an outcome of the fermentation process, an increasing interest is developed in bee products. Bee bread (BB) is a different product intended for humans and bees, resulting from bee pollen's lactic fermentation in the honeycombs, abundant in polyphenols, nutrients (vitamins and proteins), fatty acids, and minerals. BB conservation is correlated to bacteria metabolites, mainly created by Pseudomonas spp., Lactobacillus spp., and Saccharomyces spp., which give lactic acid bacteria the ability to outperform other microbial groups. Because of enzymatic transformations, the fermentation process increases the content of new compounds. After the fermentation process is finalized, the meaningful content of lactic acid and several metabolites prevent the damage caused by various pathogens that could influence the quality of BB. Over the last few years, there has been an increase in bee pollen fermentation processes to unconventional dietary and functional supplements. The use of the chosen starters improves the bioavailability and digestibility of bioactive substances naturally found in bee pollen. As a consequence of enzymatic changes, the fermentation process enhances BB components and preserves them against loss of characteristics. In this aspect, the present review describes the current biotechnological advancements in the development of BB rich in beneficial components derived from bee pollen fermentation and its use as a food supplement and probiotic product with increased shelf life and multiple health benefits.

Probiotics Function in Preventing Atopic Dermatitis in Children

Atopic dermatitis (AD) is a chronic inflammatory skin disorder characterized by relapsing eczematous injuries and severe pruritus. In the last few years, the AD prevalence has been increasing, reaching 20% in children and 10% in adults in high-income countries. Recently, the potential role of probiotics in AD prevention has generated considerable interest. As many clinical studies show, the gut microbiota is able to modulate systemic inflammatory and immune responses influencing the development of sensitization and allergy. Probiotics are used increasingly against AD. However, the molecular mechanisms underlying the probiotics mediated anti-allergic effect remain unclear and there is controversy about their efficacy. In this narrative review, we examine the actual evidence on the effect of probiotic supplementation for AD prevention in the pediatric population, discussing also the potential biological mechanisms of action in this regard.

Do Probiotics in Pregnancy Reduce Allergies and Asthma in Infancy and Childhood? A Systematic Review

The maternal immune system is very important in the development of the foetal immune system. Probiotics have been shown to help regulate immune responses. Therefore, it is possible that the administration of probiotics to pregnant women could influence the development of the foetal immune system, reducing the likelihood of infants and children developing an allergic condition. The aim of this research was to conduct a systematic review to determine whether administering probiotics to pregnant women can reduce the incidence of allergic disease in their children. Medline, CINAHL and Embase databases were searched for randomised controlled trials (RCTs) that compared supplementation of probiotics to pregnant women to a placebo control and recorded the presentation of allergic conditions in their children. Data extracted from the study reports included their characteristics and findings. Study quality and risk of bias were assessed. From a total of 850 articles identified in the search, 6 were eligible for inclusion in this review. Two studies found no effect of maternal probiotics on the outcomes measured, two studies found that the incidence of eczema or atopic dermatitis (AD) was reduced by maternal probiotics, one study found no effect on the overall incidence of atopic sensitisation, but a reduction in a subgroup of children at high hereditary risk of allergic disease, and one study found no effect in an intention to treat analysis, but a reduction in AD in complete case analysis. The results of these studies are inconsistent but demonstrate that probiotics may have the potential to reduce infant allergies when administered prenatally, particularly in children at high risk of allergy development. There is a need for further larger-scale studies to be performed in order to provide a more definitive answer. Such studies should focus on at-risk groups.

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.

Effects of Pre/Probiotic Supplementation on Breast Milk Levels of TGF-b1, TGF-b2, and IgA: A Systematic Review and Meta-Analysis of Randomized-Controlled Trial

Background: Previous studies have proposed that the maternal intake of pre/probiotics may affect the immune composition of breast milk. Nevertheless, the available findings are contradictory. This meta-analysis aimed to examine the impact of maternal supplementation with pre/probiotics on the levels of total immunoglobulin A (IgA), secretory IgA (SIgA), transforming growth factor beta 1 (TGF-β1), and TGF-2 in breast milk. Methods: PubMed and Scopus were systematically searched using a comprehensive search strategy for eligible randomized-controlled trials published up to February 2021. A random-effects model was applied to pool weighted mean difference and 95% confidence interval (CI) as effect size. Cochran's Q statistic and the I2 statistic were used to measure the between-study variance. Egger's regression test was used to assess publication bias. Results: A total of 12 different studies, with a total sample size of 1722 individuals (probiotic group: 858, placebo group: 864), were included in this meta-analysis. In the overall analysis, compared with placebo, maternal supplementation with pre/probiotics had no significant effect on concentrations of total IgA, SIgA, TGF-β1, and TGF-β2 in the breast milk. In the subgroup analysis, pre/probiotics did not affect total IgA, TGF-β1, and TGF-β2 in both colostrum/transitional and mature milk. However, a significant increase in SIgA was found in colostrum/transitional milk following pre/probiotic administration (WMD = 19.33, 95% CI: 0.83-37.83; p = 0.04), without evidence for remarkable heterogeneity (I² = 0.0, p = 0.57). Conclusions: Maternal supplementation with pre/probiotics may increase SIgA in colostrum/transitional milk, without any effect on total IgA, TGF-β1, and TGF-β2.

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.

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.

The maternal gut microbiome during pregnancy and offspring allergy and asthma

Environmental exposures during pregnancy that alter both the maternal gut microbiome and the infant's risk of allergic disease and asthma include a traditional farm environment and consumption of unpasteurized cow's milk, antibiotic use, dietary fiber and psychosocial stress. Multiple mechanisms acting in concert may underpin these associations and prime the infant to acquire immune competence and homeostasis following exposure to the extrauterine environment. Cellular and metabolic products of the maternal gut microbiome can promote the expression of microbial pattern recognition receptors, as well as thymic and bone marrow hematopoiesis relevant to regulatory immunity. At birth, transmission of maternally derived bacteria likely leverages this in utero programming to accelerate postnatal transition from a Th2 to Th1 and Th17 dominant immune phenotypes and maturation of regulatory immune mechanisms, which in turn reduce the child's risk of allergic disease and asthma. Although our understanding of these phenomena is rapidly evolving, the field is relatively nascent, and we are yet to translate existing knowledge into interventions that substantially reduce disease risk in humans. Here we review evidence that the maternal gut microbiome impacts the offspring's risk of allergic disease and asthma, discuss challenges and future directions for the field, and propose the hypothesis that maternal carriage of Prevotella copri during pregnancy decreases the offspring's risk of allergic disease via production of succinate which in turn promotes bone marrow myelopoiesis of dendritic cell precursors in the fetus.

Probiotics as Adjuvants in Vaccine Strategy: Is There More Room for Improvement?

BACKGROUND

It has been recognized that microbiota plays a key role in shaping immune system maturation and activity. Since probiotic administration influences the microbiota composition and acts as a biological response modifier, the efficacy of an adjuvant for boosting vaccine-specific immunity is investigated.

METHODS

A review of the literature was performed, starting from the mechanisms to laboratory and clinical evidence.

RESULTS

The mechanisms, and in vitro and animal models provide biological plausibility for microbiota use. Probiotics have been investigated as adjuvants in farm conditions and as models to understand their potential in human vaccinations with promising results. In human studies, although probiotics were effective in ameliorating seroconversion to vaccines for influenza, rotavirus and other micro-organisms, the results for clinical use are still controversial, especially in particular settings, such as during the last trimester of pregnancy.

CONCLUSION

Although this topic remains controversial, the use of probiotics as adjuvant factors in vaccination represents a strategic key for different applications. The available data are deeply influenced by heterogeneity among studies in terms of strains, timing and duration of administration, and patients. Although these do not allow us to draw definitive conclusions, probiotics as adjuvants in vaccination should be considered in future studies, especially in the elderly and in children, where vaccine effectiveness and duration of immunization really matter.

Probiotic Supplementation and Human Milk Cytokine Profiles in Japanese Women: A Retrospective Study from an Open-Label Pilot Study

The benefits of probiotic supplementation to lactating mothers on human milk cytokines are inconclusive. Thus, we performed a comprehensive open-label pilot trial analysis of 27 human milk cytokines in lactating women with allergies (one to three months postpartum) to determine the effect of supplementation with a mixture of new probiotic strains. Participants voluntarily joined the probiotic (n = 41) or no supplementation control (n = 19) groups. The probiotic group took three probiotic tablets (Lactobacillus casei LC5, Bifidobacterium longum BG7, and Bacillus coagulans SANK70258) daily for one to three months postpartum. Milk samples were collected at one, two, and three months postpartum, and cytokine levels were measured using multiplex assays. The effects were analyzed using multivariate regression models. Eleven cytokines showed a positive rate of over 50% in the milk samples throughout testing in both groups. The positive rates of IL-1 receptor antagonist and IL-7 changed significantly with lactation progression in logistic regression models after adjusting for time and supplementation, whereas rates of other cytokines showed no significant differences. The lactational change patterns of IL-10 concentrations differed significantly between the two groups. A short-term supplementation of probiotics affects human milk cytokine levels in lactating women with a possible placebo effect still existing. Future placebo-controlled studies are needed to support these results, based on the estimated sample sizes in this study.

Strategies and Future Opportunities for the Prevention, Diagnosis, and Management of Cow Milk Allergy

The prevalence of food allergy has increased over the last 20-30 years, including cow milk allergy (CMA) which is one of the most common causes of infant food allergy. International allergy experts met in 2019 to discuss broad topics in allergy prevention and management of CMA including current challenges and future opportunities. The highlights of the meeting combined with recently published developments are presented here. Primary prevention of CMA should start from pre-pregnancy with a focus on a healthy lifestyle and food diversity to ensure adequate transfer of inhibitory IgG- allergen immune complexes across the placenta especially in mothers with a history of allergic diseases and planned c-section delivery. For non-breastfed infants, there is controversy about the preventive role of partially hydrolyzed formulae (pHF) despite some evidence of health economic benefits among those with a family history of allergy. Clinical management of CMA consists of secondary prevention with a focus on the development of early oral tolerance. The use of extensive Hydrolysate Formulae (eHF) is the nutrition of choice for the majority of non-breastfed infants with CMA; potentially with pre-, probiotics and LCPUFA to support early oral tolerance induction. Future opportunities are, among others, pre- and probiotics supplementation for mothers and high-risk infants for the primary prevention of CMA. A controlled prospective study implementing a step-down milk formulae ladder with various degrees of hydrolysate is proposed for food challenges and early development of oral tolerance. This provides a more precise gradation of milk protein exposure than those currently recommended.

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.

Asthma in the Precision Medicine Era: Biologics and Probiotics

Asthma is a major global health issue. Over 300 million people worldwide suffer from this chronic inflammatory airway disease. Typical clinical symptoms of asthma are characterized by a recurrent wheezy cough, chest tightness, and shortness of breath. The main goals of asthma management are to alleviate asthma symptoms, reduce the risk of asthma exacerbations, and minimize long-term medicinal adverse effects. However, currently available type 2 T helper cells (Th2)-directed treatments are often ineffective due to the heterogeneity of the asthma subgroups, which manifests clinically with variable and poor treatment responses. Personalized precision therapy of asthma according to individualized clinical characteristics (phenotype) and laboratory biomarkers (endotype) is the future prospect. This mini review discusses the molecular mechanisms underlying asthma pathogenesis, including the hot sought-after topic of microbiota, add-on therapies and the potential application of probiotics in the management of asthma.

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.

Maternal supplementation with Bifidobacterium breve M-16V prevents their offspring from allergic airway inflammation accelerated by the prenatal exposure to an air pollutant aerosol

Bifidobacterium breve M-16V is a probiotic bacterial strain with efficacy in infants achieved by suppressing T-helper type (Th) 2 immune responses and modulating the systemic Th1/Th2 balance. Exposure to air pollution during pregnancy increases asthma susceptibility in offspring. The aim of this study was to investigate the effects of the maternal intake of B. breve M-16V on susceptibility to asthma accelerated by prenatal exposure to air pollution. The intake of B. breve M-16V in residual oil fly ash (ROFA)-exposed pregnant mice resulted in fewer eosinophils in the bronchoalveolar lavage fluid of neonatal mice and reduced allergic lung inflammation. The expressions of Th2 cytokines including IL-5 and IL-13 were decreased in neonatal mice from ROFA-exposed mothers fed B. breve M-16V. The analysis of fecal microbiota from neonatal mice revealed that the intake of B. breve M-16V by mothers changed the composition of fecal microbiota in neonatal mice, which resulted in a decreased population of Firmicutes. Moreover, several bacterial strains of fecal microbiota from neonatal mice had a strong correlation with Th2 cytokines and histological score. These results suggest that the maternal intake of M-16V might have beneficial effects in neonates by preventing and/or alleviating allergic reactions accelerated by prenatal exposure to air pollution.

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.

Disease managing capacities and mechanisms of host effects of lactic acid bacteria

Consumption of lactic acid bacteria (LAB) has been suggested to confer health-promoting effects on the host. However, effects of LABs have been reported to be species- and strain-specific and the mechanisms involved are subjects of discussion. Here, the possible mechanisms by which LABs induce antipathogenic, gut barrier enhancing and immune modulating effects in consumers are reviewed. Specific strains for which it has been proven that health is improved by these mechanisms are discussed. However, most strains probably act via several or combinations of mechanisms depending on which effector molecules they express. Current insight is that these effector molecules are either present on the cell wall of LAB or are excreted. These molecules are reviewed as well as the ligand binding receptors in the host. Also postbiotics are discussed. Finally, we provide an overview of the efficacy of LABs in combating infections caused by Helicobacter pylori, Salmonella, Escherichia coli, Streptococcus pneumoniae, and influenza virus, in controlling gut inflammatory diseases, in managing allergic disorders, and in alleviating cancer.

Oral and nasal probiotic administration for the prevention and alleviation of allergic diseases, asthma and chronic obstructive pulmonary disease

Interaction between a healthy microbiome and the immune system leads to body homeostasis, as dysbiosis in microbiome content and loss of diversity may result in disease development. Due to the ability of probiotics to help and modify microbiome constitution, probiotics are now widely used for the prevention and treatment of different gastrointestinal, inflammatory, and, more recently, respiratory diseases. In this regard, chronic respiratory diseases including chronic obstructive pulmonary disease (COPD), asthma and allergic rhinitis are among the most common and complicated respiratory diseases with no specific treatment until now. Accordingly, many studies have evaluated the therapeutic efficacy of probiotic administration (mostly via the oral route and much lesser nasal route) on chronic respiratory diseases. We tried to summarise and evaluate these studies to give a perspective of probiotic therapy via both the oral and nasal routes for respiratory infections (in general) and chronic respiratory diseases (specifically). We finally concluded that probiotics might be useful for allergic diseases. For asthmatic patients, probiotics can modulate serum cytokines and IgE and decrease eosinophilia, but with no significant reduction in clinical symptoms. For COPD, only limited studies were found with uncertain clinical efficacy. For intranasal administration, although some studies propose more efficiency than the oral route, more clinical evaluations are warranted.

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.

The effect of an educational program for pregnant women to prevent allergic diseases in infants: study protocol for a randomized controlled trial

BACKGROUND

Allergic diseases in infants have dramatically increased in developed countries during the past few decades. To date, extensive research has been done on risk factors for allergies in infancy, and preventive measures against them. However, the effect of the primary approach to preventing infantile allergy is still limited. The aim of this trial is to evaluate whether prenatal education interventions, including the latest public research results on allergic diseases, prevent the onset of infant allergies.

METHODS/DESIGN

We designed a randomized controlled, two-arm (standard prenatal education vs our education), parallel-group, assessor-blind trial. A sample of 120 pregnant women will be recruited at Chiba Aiyu-kai Kinen Hospital and allocation is by computer-generated randomization. Pregnant women in the intervention arm participate in the childbirth education program established by the specialist and a pediatric allergy educator. The program was developed based on evidences supporting interventions on primary prevention, which are suggested to be beneficial to infantile allergies in recent studies. The primary objective of the study is to determine whether it is possible to establish effective behaviors for allergy prevention in early infancy in the children of pregnant women who participate in an educational program developed by pediatric allergy specialists. Four months after birth, their behaviors will be compared against those of pregnant women who did not participate in the program.

DISCUSSION

Allergies are common in many individuals worldwide, and can be present from babyhood through the person's lifetime. One of the strong points of this study is that it should provide pregnant women with accumulated information on preventive knowledge against allergy, that can be effective in some cases, and that women can apply a combination of these behaviors before and after pregnancy. The results of our program will be publicized to help change the behaviors of mothers, and, if the program is effective, for preventing allergies in infants, it will be disclosed worldwide as a new preventive strategy for allergy in infants.

TRIAL REGISTRATION

UMIN-CTR, ID: UMIN000034730 Retrospectively registered on 1 December 2018.

Effect of probiotic supplementation in pregnant women: a meta-analysis of randomised controlled trials

Probiotics are being used increasingly in pregnant women, whereas the efficiency on pregnancy outcomes is yet lacking. PubMed, Embase and the Cochrane Library were searched. Relative risks (RR) or weighted mean differences (WMD) with 95 % CI were employed to calculate the summary outcomes. A total of eighteen randomised controlled trials (RCT) including 4356 pregnant women were eligible. The summary RR indicated that probiotic supplementation was associated with a significant decrease in the risk of atopic eczema (RR 0·68; 95 % CI 0·58, 0·81; P < 0·001) and eczema (RR 0·79; 95 % CI 0·68, 0·91; P = 0·002) without significant heterogeneity. Probiotic supplementation was associated with a prolonged gestational age (WMD 0·09; 95 % CI 0·04, 0·15; P = 0·001) with insignificant heterogeneity, whereas no significant effect was exerted on birth weight (P = 0·851). The risks of death (RR 0·34; 95 % CI 0·13, 0·91; P = 0·031) and necrotising enterocolitis (NEC) (RR 0·38; 95 % CI 0·18, 0·81; P = 0·012) were significantly reduced in pregnant women receiving probiotics without evidence of heterogeneity. These findings suggested that probiotics in pregnant women were beneficial for atopic eczema, eczema, gestational age, death and NEC.

Protective Effect of Breastfeeding on the Adverse Health Effects Induced by Air Pollution: Current Evidence and Possible Mechanisms

Air pollution is a major social, economic, and health problem around the world. Children are particularly susceptible to the negative effects of air pollution due to their immaturity and excessive growth and development. The aims of this narrative review were to: (1) summarize evidence about the protective effects of breastfeeding on the adverse health effects of air pollution exposure, (2) define and describe the potential mechanisms underlying the protective effects of breastfeeding, and (3) examine the potential effects of air pollution on breastmilk composition and lactation. A literature search was conducted using electronic databases. Existing evidence suggests that breastfeeding has a protective effect on adverse outcomes of indoor and outdoor air pollution exposure in respiratory (infections, lung function, asthma symptoms) and immune (allergic, nervous and cardiovascular) systems, as well as under-five mortality in both developing and developed countries. However, some studies reported no protective effect of breastfeeding or even negative effects of breastfeeding for under-five mortality. Several possible mechanisms of the breastfeeding protective effect were proposed, including the beneficial influence of breastfeeding on immune, respiratory, and nervous systems, which are related to the immunomodulatory, anti-inflammatory, anti-oxidant, and neuroprotective properties of breastmilk. Breastmilk components responsible for its protective effect against air pollutants exposure may be long chain polyunsaturated fatty acids (LC PUFA), antioxidant vitamins, carotenoids, flavonoids, immunoglobins, and cytokines, some of which have concentrations that are diet-dependent. However, maternal exposure to air pollution is related to increased breastmilk concentrations of pollutants (e.g., Polycyclic aromatic hydrocarbons (PAHs) or heavy metals in particulate matter (PM)). Nonetheless, environmental studies have confirmed that breastmilk's protective effects outweigh its potential health risk to the infant. Mothers should be encouraged and supported to breastfeed their infants due to its unique health benefits, as well as its limited ecological footprint, which is associated with decreased waste production and the emission of pollutants.

Translating Recent Microbiome Insights in Otitis Media into Probiotic Strategies

The microbiota of the upper respiratory tract (URT) protects the host from bacterial pathogenic colonization by competing for adherence to epithelial cells and by immune response regulation that includes the activation of antimicrobial and (anti-)inflammatory components. However, environmental or host factors can modify the microbiota to an unstable community that predisposes the host to infection or inflammation. One of the URT diseases most often encountered in children is otitis media (OM). The role of pathogenic bacteria like Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis in the pathogenesis of OM is well documented. Results from next-generation-sequencing (NGS) studies reveal other bacterial taxa involved in OM, such as Turicella and Alloiococcus Such studies can also identify bacterial taxa that are potentially protective against URT infections, whose beneficial action needs to be substantiated in relevant experimental models and clinical trials. Of note, lactic acid bacteria (LAB) are members of the URT microbiota and associated with a URT ecosystem that is deemed healthy, based on NGS and some experimental and clinical studies. These observations have formed the basis of this review, in which we describe the current knowledge of the molecular and clinical potential of LAB in the URT, which is currently underexplored in microbiome and probiotic research.

Reviewing the evidence on breast milk composition and immunological outcomes

A large number of biologically active components have been found in human milk (HM), and in both human and animal models, studies have provided some evidence suggesting that HM composition can be altered by maternal exposures, subsequently influencing health outcomes for the breastfed child. Evidence varies from the research studies on whether breastfeeding protects the offspring from noncommunicable diseases, including those associated with immunological dysfunction. It has been hypothesized that the conflicting evidence results from HM composition variations, which contain many immune active molecules, oligosaccharides, lactoferrin, and lysozyme in differing concentrations, along with a diverse microbiome. Determining the components that influence infant health outcomes in terms of both short- and long-term sequelae is complicated by a lack of understanding of the environmental factors that modify HM constituents and thereby offspring outcomes. Variations in HM immune and microbial composition (and the differing infantile responses) may in part explain the controversies that are evidenced in studies that aim to evaluate the prevalence of allergy by prolonged and exclusive breastfeeding. HM is a "mixture" of immune active factors, oligosaccharides, and microbes, which all may influence early immunological outcomes. This comprehensive review provides an in-depth overview of existing evidence on the studied relationships between maternal exposures, HM composition, vaccine responses, and immunological outcomes.

Transforming growth factor beta in human milk and allergic outcomes in children: A systematic review

BACKGROUND

Human milk (HM) transforming growth factor beta (TGF-β) is critical for inflammation regulation and oral tolerance promotion. Previous reports suggested that variations in HM TGF-β levels are associated with allergic outcomes.

OBJECTIVE

We undertook a systematic review (PROSPERO 2017 CRD42017069920) to reassess the evidence on the relationships between HM TGF-β and allergic outcomes in children.

METHODS

Electronic bibliographic databases (MEDLINE, EMBASE and Cochrane Library) were systematically searched. Two independent reviewers screened reference lists, extracted the data and assessed risk of bias using the National Institute for Clinical Excellence methodological checklist.

RESULTS

A total of 21 studies were identified. Sixteen studies assessed relationships between HM TGF-β and risk of eczema; 14, allergic sensitization; nine, wheezing/asthma; six, food allergy; three, allergic rhinitis/conjunctivitis. Five cohorts (5/18, 28%) reported a protective effect of TGF-β1, while 3 (3/10, 30%) suggested increased risk of allergic outcomes development and 1 (1/10, 10%), a protective effect of TGF-β2 on eczema. Meta-analysis was not possible due to significant heterogeneity in methodology, age of outcome assessment and differing statistical approaches. 71% (15/21) of studies carried a high risk of bias.

CONCLUSION AND CLINICAL RELEVANCE

In contrast with previous findings, we did not find strong evidence of associations between HM TGF-β and allergic outcomes. Differences in studies' methodology and outcomes do not allow unconditional rejection or acceptance of the hypothesis that HM TGF-β influences the risk of allergy development. Future studies on diverse populations employing standardized methods, accurate phenotyping of outcomes and evaluation of the effect of TGF-β in combination with other HM immune markers, microbiome and oligosaccharides are required.

Probiotic Supplementation for Prevention of Atopic Dermatitis in Infants and Children: A Systematic Review and Meta-analysis

BACKGROUND

Probiotic supplementation in early life may be effective in preventing atopic dermatitis (AD); however, results regarding efficacy have been controversial.

OBJECTIVE

The aim of our study was to investigate the effect of probiotic supplementation on the risk of AD.

METHODS

We systematically searched PubMed, EBSCO, Embase and Web of Science databases up to 8 March 2018 for potentially relevant studies regarding probiotic supplementation and AD. Included infants and children were those with probiotic exposure in utero and/or after birth who were not previously diagnosed with AD. We calculated the odds ratios (ORs) and 95% confidence intervals (CIs) and used the Jadad and Newcastle-Ottawa scales to assess methodologic quality.

RESULTS

A total of 28 studies met the inclusion criteria. Compared with controls, probiotic treatment was associated with a reduced risk of AD (OR 0.69; 95% CI 0.58-0.82, P < 0.0001). The use of probiotics during both the prenatal and the postnatal period significantly reduced the incidence of AD (OR 0.67; 95% CI 0.54-0.82); however, analysis of studies of probiotics given prenatally only or postnatally only did not reach statistical significance.

CONCLUSIONS

Our meta-analysis showed that probiotic supplementation during both the prenatal and the postnatal period reduced the incidence of AD in infants and children. Our findings suggest that starting probiotic treatment during gestation and continuing through the first 6 months of the infant's life may be of benefit in the prevention of AD.