Prebiotics for the prevention of allergies: A systematic review and meta-analysis of randomized controlled trials

Gut microbiota and skin pathologies: Mechanism of the gut-skin axis in atopic dermatitis and psoriasis

Atopic dermatitis (AD) and psoriasis are chronic skin diseases with a global impact, posing significant challenges to public health systems and severely affecting patients' quality of life. This review delves into the key role of the gut microbiota in these diseases, emphasizing the importance of the gut-skin axis in inflammatory mediators and immune regulation and revealing a complex bidirectional communication system. We comprehensively assessed the pathogenesis, clinical manifestations, and treatment strategies for AD and psoriasis, with a particular focus on how the gut microbiota and their metabolites influence disease progression via the gut-skin axis. In addition, personalized treatment plans based on individual patient microbiome characteristics have been proposed, offering new perspectives for future treatment approaches. We call for enhanced interdisciplinary cooperation to further explore the interactions between gut microbiota and skin diseases and to assess the potential of drugs and natural products in modulating the gut-skin axis, aiming to advance the treatment of skin diseases.

Importance of dietary fiber in children

Dietary fibers (DFs) are essential components of human nutrition and are principally defined as non-digestible carbohydrates (oligosaccharides and polysaccharides) usually classified by their physicochemical and physiological characteristics (water solubility, viscosity, fermentability, and bulking effect). Unfortunately, there is limited information on dietary fiber recommendations for children, and the evidence on their effect on health and symptom control is mainly available for the adult population. Therefore, this review aims to give a comprehensive overview of the characteristics and dietary sources of dietary fiber and their potential health benefits in healthy children but also their potential use in the treatment of sick children.

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.

Characteristics of infant formula consumed in the first months of life and allergy in the EDEN mother-child cohort

The evidence regarding the association between infant formula (IF) composition and the prevention of allergy and respiratory diseases remains sparse and inconclusive. This study aimed to evaluate whether some IF characteristics were associated with the risk of allergy or respiratory diseases in childhood. Among 1243 formula-fed children from the EDEN mother-child cohort, IF characteristics concerning long-chain polyunsaturated fatty acids (LCPUFAs) enrichment, prebiotic/probiotic enrichment, and hydrolysis of proteins were identified from the ingredients list. Eczema, wheezing, food allergy, asthma, and allergic rhinitis up to age 8 years were prospectively collected and summarized into four allergic and respiratory multimorbidity clusters. Associations between 4-month IF characteristics and risk of allergy or respiratory diseases were tested using logistic regressions adjusted on main confounders. The consumption of LCPUFA-enriched formula was not linked to allergic and respiratory multimorbidity clusters, but to a lower risk of any allergy, eczema, and wheezing. Probiotic-enriched formula consumption was associated with a lower risk of belonging to the 'Allergy without asthma' cluster (odds ratio [OR] [95% confidence interval, CI] = 0.63 [0.40-0.99]), and consumption of a formula enriched in Bifidobacterium lactis was associated with a lower risk of any allergy (OR [95% CI] = 0.59 [0.41-0.85]). Partially hydrolysed formula (pHF) consumption was associated with a higher risk of belonging to the 'Allergy without asthma' cluster (OR [95% CI] = 2.73 [1.65-4.51]). This study confirms the positive association between pHF consumption and the risk of allergy found in previous observational studies and suggests that consumption of LCPUFA-enriched or probiotic-enriched formula was associated with a lower risk of allergy.

Nuts, vegetables, fruits, and protein dietary pattern during pregnancy is inversely associated with risk of childhood allergies: a case-control study

Allergic diseases are prevalent chronic conditions among children and can lead to significant health and economic issues. It is hypothesized that healthy and high quality diet during pregnancy can prevent the onset of allergic diseases in offspring. This study aimed to investigate the potential relationship between major dietary patterns during pregnancy and allergies in children under one year of age. This case-control study was conducted involving 244 participants (122 mothers of allergic children and 122 healthy controls) who visited pediatricians and allergy outpatient clinics in Khuzestan Province, Iran, between June 2022 and March 2023. Demographic information was recorded using a socio-demographic questionnaire. A food frequency questionnaire was used to identify the foods consumed during pregnancy. Major dietary patterns were extracted using principal component analysis, and the potential relationship between these patterns and childhood allergies was investigated using multivariable logistic regression models. The crude odds ratio (OR) analysis showed that the fourth quartile of "Nut, vegetables, fruits, and protein" dietary pattern was associated with lower occurrence of childhood allergies (OR: 0.214, 95% CI = 0.068-0.679; P trend = 0.211). After adjusting for cofactors in Model 3, this association was still observed in the fourth quartile (OR = 0.108, 95% CI = 0.019-0.613; P trend, 0.001). However, no significant association was observed between "Carbohydrate and cereals" and "Salty" dietary patterns and childhood allergies. The study findings suggest that a maternal dietary pattern rich in nuts, vegetables, and fruits during pregnancy may reduce the risk of allergic diseases in offspring.

Shaping Microbiota During the First 1000 Days of Life

Given that the host-microbe interaction is shaped by the immune system response, it is important to understand the key immune system-microbiota relationship during the period from conception to the first years of life. The present work summarizes the available evidence concerning human reproductive microbiota, and also, the microbial colonization during early life, focusing on the potential impact on infant development and health outcomes. Furthermore, we conclude that some dietary strategies including specific probiotics and other-biotics could become potentially valuable tools to modulate the maternal-neonatal microbiota during this early critical window of opportunity for targeted health outcomes throughout the entire lifespan.

Primary Prevention of Allergy - Is It Feasible?

The allergy epidemic has been attributed to environmental influences related to urbanization and the modern lifestyle. In this regard, various theories exploring the role of microbes (hygiene, old friends, microbiota, and biodiversity hypotheses), and the epithelial barrier (epithelial, dual allergen exposure and vitamin D hypotheses) have been proposed. These hypotheses have guided clinical studies that led to the formulation of intervention strategies during the proposed window of opportunity dubbed as the "first thousand days." The most significant intervention is a paradigm shift from allergen avoidance to early introduction of allergenic foods, particularly egg and peanut, around 6 months of age for the prevention of food allergy. This recommendation has been adopted globally and included in allergy prevention guidelines. Other strategies with less robust clinical evidence include: encouraging a healthy balanced diet, rich in fish, during pregnancy; continuing allergenic food intake during pregnancy and lactation; vitamin D supplementation in pregnant women with asthma; discouraging social indications for caesarean section delivery; judicious use of antibiotics in early childhood; daily emollient use from birth in high risk babies; and avoiding cow's milk formula use in the first week of life. However, if early supplementation with cow's milk formula is required, continuing at least 10 mL of formula daily until age 2 months may be considered. Translating these strategies to public health and clinical practice is still a work in progress. Long-term population studies are crucial to assess the feasibility of these measures on allergy prevention.

The Role of the Microbiome in the Pathogenesis and Treatment of Asthma

The role of the microbiome in the pathogenesis and treatment of asthma is significant. The purpose of this article is to show the interplay between asthma and the microbiome, and main areas that require further research are also highlighted. The literature search was conducted using the PubMed database. After a screening process of studies published before May 2023, a total of 128 articles were selected in our paper. The pre-treatment bronchial microbiome in asthmatic patients plays a role in their responsiveness to treatment. Gut microbiota and its dysbiosis can contribute to immune system modulation and the development of asthma. The association between the microbiome and asthma is complex. Further research is necessary to clarify which factors might moderate that relationship. An appropriate gut microbiome and its intestinal metabolites are a protective factor for asthma development. Prebiotics and certain dietary strategies may have a prophylactic or therapeutic effect, but more research is needed to establish final conclusions. Although the evidence regarding probiotics is ambiguous, and most meta-analyses do not support the use of probiotic intake to reduce asthma, several of the most recent studies have provided promising effects. Further studies should focus on the investigation of specific strains and the examination of their mechanistic and genetic aspects.

Bacterial Metabolites: A Link between Gut Microbiota and Dermatological Diseases

Dysbiosis has been identified in many dermatological conditions (e.g., psoriasis, atopic dermatitis, systemic lupus erythematosus). One of the ways by which the microbiota affect homeostasis is through microbiota-derived molecules (metabolites). There are three main groups of metabolites: short-chain fatty acids (SCFAs), tryptophan metabolites, and amine derivatives including trimethylamine N-oxide (TMAO). Each group has its own uptake and specific receptors through which these metabolites can exert their systemic function. This review provides up-to-date knowledge about the impact that these groups of gut microbiota metabolites may have in dermatological conditions. Special attention is paid to the effect of microbial metabolites on the immune system, including changes in the profile of the immune cells and cytokine disbalance, which are characteristic of several dermatological diseases, especially psoriasis and atopic dermatitis. Targeting the production of microbiota metabolites may serve as a novel therapeutic approach in several immune-mediated dermatological diseases.

Biotics in atopic diseases: state of the art and future perspectives

Prevalence of allergic diseases has growing in recent decades, being a significant burden for patients and their families. Different environmental factors, acting in early life, can significantly affect the timing and diversity of bacterial colonization and the immune system development. Growing evidence points to a correlation between early life microbial perturbation and development of allergic diseases. Besides, changes in the microbiota in one body site may influence other microbiota communities at distance by different mechanisms, including microbial-derived metabolites, mainly the short chain fatty acids (SCFA). Hence, there has been an increasing interest on the role of "biotics" (probiotics, prebiotics, symbiotics and postbiotics) in shaping dysbiosis and modulating allergic risk. Systemic type 2 inflammation is emerging as a common pathogenetic pathway of allergic diseases, intertwining communication with the gut mcirobiota. The aim of this review was to provide an update overview of the current knowledge of biotics in prevention and treatment of allergic diseases, also addressing research gaps which need to be filled.

Role of dietary fiber in promoting immune health-An EAACI position paper

Microbial metabolism of specific dietary components, such as fiber, contributes to the sophisticated inter-kingdom dialogue in the gut that maintains a stable environment with important beneficial physiological, metabolic, and immunological effects on the host. Historical changes in fiber intake may be contributing to the increase of allergic and hypersensitivity disorders as fiber-derived metabolites are evolutionarily hardwired into the molecular circuitry governing immune cell decision-making processes. In this review, we highlight the importance of fiber as a dietary ingredient, its effects on the microbiome, its effects on immune regulation, the importance of appropriate timing of intervention to target any potential window of opportunity, and potential mechanisms for dietary fibers in the prevention and management of allergic diseases. In addition, we review the human studies examining fiber or prebiotic interventions on asthma and respiratory outcomes, allergic rhinitis, atopic dermatitis, and overall risk of atopic disorders. While exposures, interventions, and outcomes were too heterogeneous for meta-analysis, there is significant potential for using fiber in targeted manipulations of the gut microbiome and its metabolic functions in promoting immune health.

Gut microbiota: A target for prebiotics and probiotics in the intervention and therapy of food allergy

Food allergy has become a major public health problem all over the world. Evidence showed that allergic reactions induced by food proteins often lead to disturbances in the gut microbiota (symbiotic bacteria). Gut microbiota plays an important role in maintaining the balance between intestinal immune tolerance and allergic reactions. Dietary intervention has gradually become an important method for the prevention and treatment of allergic diseases, and changing the composition of gut microbiota through oral intake of prebiotics and probiotics may serve as a new effective adjuvant treatment measure for allergic diseases. In this paper, the main mechanism of food allergy based on intestinal immunity was described firstly. Then, the clinical and experimental evidence showed that different prebiotics and probiotics affect food allergy by changing the structure and composition of gut microbiota was summarized. Moreover, the molecular mechanism in which the gut microbiota and their metabolites may directly or indirectly regulate the immune system or intestinal epithelial barrier function to affect food immune tolerance of host were also reviewed to help in the development of food allergy prevention and treatment strategies based on prebiotics and probiotics.

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.

English Version of Clinical Practice Guidelines for the Management of Atopic Dermatitis 2021

This is the English version of the Clinical Practice Guidelines for the Management of Atopic Dermatitis 2021. Atopic dermatitis (AD) is a disease characterized by relapsing eczema with pruritus as a primary lesion. In Japan, from the perspective of evidence-based medicine, the current strategies for the treatment of AD consist of three primary measures: (i) use of topical corticosteroids, tacrolimus ointment, and delgocitinib ointment as the main treatment of the inflammation; (ii) topical application of emollients to treat the cutaneous barrier dysfunction; and (iii) avoidance of apparent exacerbating factors, psychological counseling, and advice about daily life. In the present revised guidelines, descriptions of three new drugs, namely, dupilumab, delgocitinib, and baricitinib, have been added. The guidelines present recommendations to review clinical research articles, evaluate the balance between the advantages and disadvantages of medical activities, and optimize medical activity-related patient outcomes with respect to several important points requiring decision-making in clinical practice.

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.

Novel potential treatable traits in asthma: Where is the research taking us?

Asthma is a complex, heterogeneous disease in which the underlying mechanisms are not fully understood. Patients are often grouped into phenotypes (based on clinical, biologic, and physiologic characteristics) and endotypes (based on distinct genetic or molecular mechanisms). Recently, patients with asthma have been broadly split into 2 phenotypes based on their levels of type 2 inflammation: type 2 and non-type 2 asthma. However, this approach is likely oversimplified, and our understanding of the non-type 2 mechanisms in asthma remains extremely limited. A better understanding of asthma phenotypes and endotypes may assist in development of drugs for new therapeutic targets in asthma. One approach is to identify "treatable traits," which are specific patient characteristics related to phenotypes and endotypes that can be targeted by therapies. This review will focus on emerging treatable traits in asthma and aim to describe novel patient subgroups and endotypes that may represent the next step in the search for new therapeutic approaches.

Nutrition in Asthma

An emerging body of evidence suggests that diet plays an important role in both the development and management of asthma. The relationship between dietary intake and asthma risk has been explored in epidemiological studies, though intervention trials examining the effects of nutrient intake and dietary patterns on asthma management are scarce. Evidence for diets high in fruits and vegetables, antioxidants, omega-3 fatty acids and soluble fiber such as the Mediterranean diet is conflicting. However, some studies suggest that these diets may reduce the risk of asthma, particularly in young children, and could have positive effects on disease management. In contrast, a Westernized dietary pattern, high in saturated fatty acids, refined grains, and sugars may promote an inflammatory environment resulting in the onset of disease and worsening of asthma outcomes. This review will summarize the state of the evidence for the impact of whole dietary patterns, as well as individual nutrients on the prevalence and management of asthma.

Primary Prevention of Pediatric Asthma through Nutritional Interventions

Asthma is the most common chronic non-communicable disease in children, the pathogenesis of which involves several factors. The increasing burden of asthma worldwide has emphasized the need to identify the modifiable factors associated with the development of the disease. Recent research has focused on the relationship between dietary factors during the first 1000 days of life (including pregnancy)—when the immune system is particularly vulnerable to exogenous interferences—and allergic outcomes in children. Specific nutrients have been analyzed as potential targets for the prevention of childhood wheeze and asthma. Recent randomized controlled trials show that vitamin D supplementation during pregnancy, using higher doses than currently recommended, may be protective against early childhood wheezing but not school-age asthma. Omega-3 fatty acid supplementation during pregnancy and infancy may be associated with a reduced risk of childhood wheeze, although the evidence is conflicting. Data from observational studies suggest that some dietary patterns during pregnancy and infancy might also influence the risk of childhood asthma. However, the quality of the available evidence is insufficient to allow recommendations regarding dietary changes for the prevention of pediatric asthma. This review outlines the available high-quality evidence on the role of prenatal and perinatal nutritional interventions for the primary prevention of asthma in children and attempts to address unmet areas for future research in pediatric asthma prevention.

Early intervention and prevention of allergic diseases

Food allergy (FA) is now one of the most common chronic diseases of childhood often lasting throughout life and leading to significant worldwide healthcare burden. The precise mechanisms responsible for the development of this inflammatory condition are largely unknown; however, a multifactorial aetiology involving both environmental and genetic contributions is well accepted. A precise understanding of the pathogenesis of FA is an essential first step to developing comprehensive prevention strategies that could mitigate this epidemic. As it is frequently preceded by atopic dermatitis and can be prevented by early antigen introduction, the development of FA is likely facilitated by the improper initial presentation of antigen to the developing immune system. Primary oral exposure of antigens allowing for presentation via a well-developed mucosal immune system, rather than through a disrupted skin epidermal barrier, is essential to prevent FA. In this review, we present the data supporting the necessity of (1) an intact epidermal barrier to prevent epicutaneous antigen presentation, (2) the presence of specific commensal bacteria to maintain an intact mucosal immune system and (3) maternal/infant diet diversity, including vitamins and minerals, and appropriately timed allergenic food introduction to prevent FA.

OUP accepted manuscript

BACKGROUND

An increasing number of infant and follow-on formulas are enriched with probiotics and/or prebiotics; however, evidence for health effects of such enrichment in early childhood remains inconclusive.

OBJECTIVES

The present study aimed to assess whether the consumption of formula enriched with probiotics or prebiotics was associated with the risk of infection and allergic diseases in early childhood.

METHODS

Analyses involved data for 8389 formula-fed children from the Etude Longitudinale Française depuis l'Enfance (ELFE) cohort. Enrichment of the formula with probiotics or prebiotics that was consumed from the age of 2-10 mo was identified by the formula ingredient list. Lower respiratory tract infection (LRTI), upper respiratory tract infection (URTI), gastrointestinal infection, wheezing, asthma, food allergy, and itchy rash were prospectively reported by parents up to the age of 5.5 y. Adjusted logistic regression models were used to assess associations between the consumption of enriched formula and risk of infection and allergic diseases.

RESULTS

Aged 2 mo, more than half of formula-fed infants consumed the probiotic-enriched formula and only 1 in 10 consumed the prebiotic-enriched formula. Consumption of the Bifidobacterium lactis-enriched formula at 2 mo was associated with a lower risk of LRTI [OR (95% CI) = 0.84 (0.73-0.96)]. Consumption of the Bifidobacterium breve-enriched formula up to 6 mo was associated with a higher risk of LRTI [OR (95% CI) = 1.75 (1.29-2.38)] and asthma [OR (95% CI) = 1.95 (1.28-2.97)], whereas its consumption from 6 to 10 mo was associated with a lower risk of LRTI [OR (95% CI) = 0.64 (0.48-0.86)] and asthma [OR (95% CI) = 0.59 (0.40-0.88)]. Moreover, the consumption of Streptococcus thermophilus from 6 to 10 mo was associated with a higher risk of asthma [OR (95% CI) = 1.84 (1.29-2.63)]. No significant association was found for gastrointestinal infection, food allergy, and itchy rash. Overall, the consumption of prebiotic-enriched formula was not significantly associated with infection and allergy risk.

CONCLUSIONS

Associations between the consumption of probiotic-enriched formula and risk of respiratory symptoms differ according to the strain considered and consumption period. Further well-designed studies are needed to confirm these results.

Dietary Fibers: Effects, Underlying Mechanisms and Possible Role in Allergic Asthma Management

The prevalence of asthma is increasing, but the cause remains under debate. Research currently focuses on environmental and dietary factors that may impact the gut-lung axis. Dietary fibers are considered to play a crucial role in supporting diversity and activity of the microbiome, as well as immune homeostasis in the gut and lung. This review discusses the current state of knowledge on how dietary fibers and their bacterial fermentation products may affect the pathophysiology of allergic asthma. Moreover, the impact of dietary fibers on early type 2 asthma management, as shown in both pre-clinical and clinical studies, is described. Short-chain fatty acids, fiber metabolites, modulate host immunity and might reduce the risk of allergic asthma development. Underlying mechanisms include G protein-coupled receptor activation and histone deacetylase inhibition. These results are supported by studies in mice, children and adults with allergic asthma. Fibers might also exert direct effects on the immune system via yet to be elucidated mechanisms. However, the effects of specific types of fiber, dosages, duration of treatment, and combination with probiotics, need to be explored. There is an urgent need to further valorize the potential of specific dietary fibers in prevention and treatment of allergic asthma by conducting more large-scale dietary intervention trials.

Pediatric Obesity-Related Asthma: The Role of Nutrition and Nutrients in Prevention and Treatment

Childhood obesity rates have dramatically risen in numerous countries worldwide. Obesity is likely a factor in increased asthma risk, which is already one of the most widespread chronic respiratory pathologies. The pathogenic mechanism of asthma risk has still not yet been fully elucidated. Moreover, the role of obesity-related inflammation and pulmonary overreaction to environmental triggers, which ultimately result in asthma-like symptoms, and the importance of dietary characteristics is well recognized. Diet is an important adjustable element in the asthma development. Food-specific composition of the diet, in particular fat, sugar, and low-quality nutrients, is likely to promote the chronic inflammatory state seen in asthmatic patients with obesity. An unbalanced diet or supplementation as a way to control asthma more efficiently has been described. A personalized dietary intervention may improve respiratory symptoms and signs and therapeutic response. In this narrative review, we presented and discussed more recent literature on asthma associated with obesity among children, focusing on the risk of asthma among children with obesity, asthma as a result of obesity focusing on the role of adipose tissue as a mediator of systemic and local airway inflammation implicated in asthma regulation, and the impact of nutrition and nutrients in the development and treatment of asthma. Appropriate early nutritional intervention could possibly be critical in preventing and managing asthma associated with obesity among children.

Pharmacological Modulation of Immune Responses by Nutritional Components

The incidence of noncommunicable diseases (NCDs) has increased over the last few decades, and one of the major contributors to this is lifestyle, especially diet. High intake of saturated fatty acids and low intake of dietary fiber is linked to an increase in NCDs. Conversely, a low intake of saturated fatty acids and a high intake of dietary fiber seem to have a protective effect on general health. Several mechanisms have been identified that underlie this phenomenon. In this review, we focus on pharmacological receptors, including the aryl hydrocarbon receptor, binding partners of the retinoid X receptor, G-coupled protein receptors, and toll-like receptors, which can be activated by nutritional components and their metabolites. Depending on the nutritional component and the receptors involved, both proinflammatory and anti-inflammatory effects occur, leading to an altered immune response. These insights may provide opportunities for the prevention and treatment of NCDs and their inherent (sub)chronic inflammation. SIGNIFICANCE STATEMENT: This review summarizes the reported effects of nutritional components and their metabolites on the immune system through manipulation of specific (pharmacological) receptors, including the aryl hydrocarbon receptor, binding partners of the retinoid X receptor, G-coupled protein receptors, and toll-like receptors. Nutritional components, such as vitamins, fibers, and unsaturated fatty acids are able to resolve inflammation, whereas saturated fatty acids tend to exhibit proinflammatory effects. This may aid decision makers and scientists in developing strategies to decrease the incidence of noncommunicable diseases.

The Dietary Fiber Pectin: Health Benefits and Potential for the Treatment of Allergies by Modulation of Gut Microbiota

Purpose of Review

The incidence of allergies is increasing and has been associated with several environmental factors including westernized diets. Changes in environment and nutrition can result in dysbiosis of the skin, gut, and lung microbiota altering the production of microbial metabolites, which may in turn generate epigenetic modifications. The present review addresses studies on pectin-mediated effects on allergies, including the immune modulating mechanisms by bacterial metabolites.

Recent Findings

Recently, microbiota have gained attention as target for allergy intervention, especially with prebiotics, that are able to stimulate the growth and activity of certain microorganisms. Dietary fibers, which cannot be digested in the gastrointestinal tract, can alter the gut microbiota and lead to increased local and systemic concentrations of gut microbiota-derived short chain fatty acids (SCFAs). These can promote the generation of peripheral regulatory T cells (T_reg) by epigenetic modulation and suppress the inflammatory function of dendritic cells (DCs) by transcriptional modulation.

The dietary fiber pectin (a plant-derived polysaccharide commonly used as gelling agent and dietary supplement) can alter the ratio of Firmicutes to Bacteroidetes in gut and lung microbiota, increasing the concentrations of SCFAs in feces and sera, and reducing the development of airway inflammation by suppressing DC function.

Summary

Pectin has shown immunomodulatory effects on allergies, although the underlying mechanisms still need to be elucidated. It has been suggested that the different types of pectin may exert direct and/or indirect immunomodulatory effects through different mechanisms. However, little is known about the relation of certain pectin structures to allergies.

Nutritional Interventions to Prevent the Development of Atopic Diseases: A Focus on Cow's Milk Allergy

In the western world the prevalence of atopic diseases such as food allergies is increasing highly significantly. One of the earliest and most prevalent food allergies occurring in the first year of life is cow's milk allergy. No treatment is available and only avoidance of the cow's milk allergens prevents the occurrence of an allergic reaction. Since cow's milk allergic children have an increased risk of developing other allergies later in life, investigating nutritional strategies to prevent the development of cow's milk allergy by developing oral tolerance is of high interest. Nutritional components such as prebiotics, probiotics, synbiotics and long-chain polyunsaturated fatty acids possess potential to support the maturation of the immune system early in life that might prevent the development of cow's milk allergy. The available research, so far, shows promising results particularly on the development of eczema. However, the preventive effects of the nutritional interventions on the development of food allergy are inconclusive. Future research may benefit from the combination of various dietary components. To clarify the preventive effects of the nutritional components in food allergy more randomized clinical trials are needed.

The Role of the Environment and Exposome in Atopic Dermatitis

PURPOSE OF REVIEW

Atopic dermatitis (AD) is a chronic inflammatory skin disorder affecting up to 20% of children and up to 5% of adults worldwide, contributing to significant disease-related morbidity in this patient cohort. Its aetiopathogenesis is underpinned by multiple factors, including genetic susceptibility, skin barrier defects, a skewed cutaneous immune response and microbiome perturbation in both the skin and the gut. In this review, we aim to examine the biological effects of key environmental exposures (the sum of which is termed the "exposome") at the population, community and individual levels in order to describe their effect on AD pathogenesis.

RECENT FINDINGS

It is now understood that as well as considering the type of environmental exposure with regard to its effect on AD pathogenesis, the dosage and timing of the exposure are both critical domains that may lead to either exacerbation or amelioration of disease. In this review, we consider the effects of population-wide exposures such as climate change, migration and urbanization; community-specific exposures such as air pollution, water hardness and allergic sensitisation; and individual factors such as diet, microbiome alteration, psychosocial stress and the impact of topical and systemic therapy.

SUMMARY

This review summarises the interaction of the above environmental factors with the other domains of AD pathogenesis, namely, the inherent genetic defects, the skin barrier, the immune system and the cutaneous and gut microbiota. We specifically emphasise the timing and dosage of exposures and its effect on the cellular and molecular pathways implicated in AD.

The evidence for interventions in early childhood allergy prevention - towards a living systematic review: protocol

Background: Research in early childhood allergy prevention (ECAP) is flourishing and new intervention strategies have proven to be promising. Due to the dynamic nature of ECAP, gaps between what is known and how guidelines inform practice are likely. A living systematic review (LSR) can narrow this gap by incorporating new evidence as it becomes available. No efficacy comparisons across various ECAP interventions for similar outcomes have been carried out. Networks of randomised clinical trials can be evaluated in the context of a network meta-analysis (NMA). We aim to establish a LSR on the efficacy and safety of any intervention investigated in randomised controlled trials (RCT) to prevent the occurrence of allergic sensitisation (AS), symptoms or diagnoses of allergic diseases in infancy and early childhood (0-3 years). Methods: A baseline SR will synthesise the evidence from existing SRs of RCTs as well as RCTs not yet considered in these. After completion of the baseline SR we propose to conduct a LSR. Using this methodology, we aim to undertake constant evidence surveillance, three-monthly search updates, and review updates every three months, should new evidence emerge. Conclusions: The ECAP evidence landscape has undergone dramatic transformations and this process is likely to continue. As a response to this, a LSR offers the potential to allow more timely synthesis of new evidence as it emerges. Long gaps between updates of SRs makes it harder for guidelines and recommendations to be up to date. Users of information, such as parents, may be confused if they encounter new evidence that is not part of a trusted guideline. A LSR approach allows us to continuously search the literature and update the evidence-base of existing ECAP interventions resulting in a decreased timespan from evidence accrual to informing clinical practice.

The evidence for interventions in early childhood allergy prevention - towards a living systematic review: protocol

Background: Research in early childhood allergy prevention (ECAP) is flourishing and new intervention strategies have proven to be promising. Due to the dynamic nature of ECAP, gaps between what is known and how guidelines inform practice are likely. A living systematic review (LSR) can narrow this gap by incorporating new evidence as it becomes available. No efficacy comparisons across various ECAP interventions for similar outcomes have been carried out. Networks of randomised clinical trials can be evaluated in the context of a network meta-analysis (NMA). We aim to establish a LSR on the efficacy and safety of any intervention investigated in randomised controlled trials (RCT) to prevent the occurrence of allergic sensitisation (AS), symptoms or diagnoses of allergic diseases in infancy and early childhood (0-3 years). Methods: A baseline SR will synthesise the evidence from existing SRs of RCTs as well as RCTs not yet considered in these. After completion of the baseline SR we propose to conduct a LSR. Using this methodology, we aim to undertake constant evidence surveillance, three-monthly search updates, and review updates every three months, should new evidence emerge. Conclusions: The ECAP evidence landscape has undergone dramatic transformations and this process is likely to continue. As a response to this, a LSR offers the potential to allow more timely synthesis of new evidence as it emerges. Long gaps between updates of SRs makes it harder for guidelines and recommendations to be up to date. Users of information, such as parents, may be confused if they encounter new evidence that is not part of a trusted guideline. A LSR approach allows us to continuously search the literature and update the evidence-base of existing ECAP interventions resulting in a decreased timespan from evidence accrual to informing clinical practice.

Preventing Atopic Diseases During Childhood - Early Exposure Matters

Atopic diseases in childhood are a major burden worldwide and there is still a lack of knowledge about treatable causes. In industrialized countries such as Germany, almost every second child is sensitized to at least one common allergen. Recent studies show that although the predisposition to allergies is inherited, the adaptive immune system of neonates and infants follows a developmental trajectory and whether an allergy actually occurs depends also on timing of allergen exposure including diet as well as environmental factors. New recommendations are far from being rigid of allergen avoidance; it is rather moving toward conditions that stand for more biodiversity. The observation that introduction of peanuts or eggs early in life significantly reduced the development of a later allergy will change our recommendations for the introduction of complementary foods. This is consistent with the hygiene hypothesis that early provocation shapes the developing immune system so that it reacts appropriately. Therefore, promoting the development of tolerance is at the heart of sensible allergy prevention - and this begins with the last trimester of pregnancy. In light of this concept, actual recommendations are discussed.

Diet Modifications in Primary Prevention of Asthma. Where Do We Stand?

The steep increase in asthma prevalence, observed worldwide in recent decades, has created an urgent need to search for effective methods of its prevention. Among other environmental factors, changes in diet habits and the potential influence of individual food components on immunological processes have been extensively studied as a potential method of intervention in primary prevention of asthma. The preventive role of some nutrients has been confirmed: unpasteurized milk reduced the risk of asthma in epidemiological studies, vitamin D supplementation was effective in preventing the transient forms of wheezing in small children and high maternal intake of fish oil reduced the risk of persistent wheeze and asthma in children. However, not all studies provided consistent results, and many food ingredients are still pending for defining their role in asthma development. Moreover, a novel approach looking not only at single food ingredients, but the whole dietary patterns and diversity has recently been proposed. In this paper, we discuss the current role of nutrients in asthma primary prevention and the reasons for inconsistencies in the study results. We look at single diet components, but also the whole dietary patterns. We describe the proposed mechanisms of action at different stages of life, identify the role of modifiers and delineate future perspectives on the application of nutrients in targeting strategies for asthma primary prevention.

The Impact of Milk and Its Components on Epigenetic Programming of Immune Function in Early Life and Beyond: Implications for Allergy and Asthma

Specific and adequate nutrition during pregnancy and early life is an important factor in avoiding non-communicable diseases such as obesity, type 2 diabetes, cardiovascular disease, cancers, and chronic allergic diseases. Although epidemiologic and experimental studies have shown that nutrition is important at all stages of life, it is especially important in prenatal and the first few years of life. During the last decade, there has been a growing interest in the potential role of epigenetic mechanisms in the increasing health problems associated with allergic disease. Epigenetics involves several mechanisms including DNA methylation, histone modifications, and microRNAs which can modify the expression of genes. In this study, we focus on the effects of maternal nutrition during pregnancy, the effects of the bioactive components in human and bovine milk, and the environmental factors that can affect early life (i.e., farming, milk processing, and bacterial exposure), and which contribute to the epigenetic mechanisms underlying the persistent programming of immune functions and allergic diseases. This knowledge will help to improve approaches to nutrition in early life and help prevent allergies in the future.

Preventing food allergy in infancy and childhood: Systematic review of randomised controlled trials

BACKGROUND

This systematic review of ways to prevent immediate-onset/IgE-mediated food allergy will inform guidelines by the European Academy of Allergy and Immunology (EAACI).

METHODS

The GRADE approach was used. Eleven databases were searched from 1946 to October 2019 for randomized controlled trials (and large prospective cohort studies in the case of breastfeeding). The studies included heterogeneous interventions, populations, and outcomes and so were summarized narratively.

RESULTS

Forty-six studies examined interventions to reduce the risk of food allergy in infancy (up to 1 year) or early childhood. The following interventions for pregnant or breastfeeding women and/or infants may have little to no effect on preventing food allergy, but the evidence is very uncertain: dietary avoidance of food allergens, vitamin supplements, fish oil, probiotics, prebiotics, synbiotics, and emollients. Breastfeeding, hydrolyzed formulas, and avoiding cow's milk formula may not reduce the risk of cow's milk protein allergy; however, temporary supplementation with cow's milk formula in the first week of life may increase the risk of cow's milk allergy. Introducing well-cooked egg, but not pasteurized raw egg, from 4 to 6 months probably reduces the risk of hen's egg allergy. Introducing regular peanut consumption into the diet of an infant at increased risk beginning from 4 to 11 months probably results in a large reduction in peanut allergy in countries with a high prevalence. These conclusions about introducing peanut are based on moderate certainty evidence, from single trials in high-income countries.

CONCLUSIONS

Sixty percent of the included studies were published in the last 10 years, but much still remains to be understood about preventing food allergy. In particular, there is a need to validate the potential benefits of early introduction of food allergens in a wider range of populations.

Childhood asthma heterogeneity at the era of precision medicine: Modulating the immune response or the microbiota for the management of asthma attack

Exacerbations are a main characteristic of asthma. In childhood, the risk is increasing with severity. Exacerbations are a strong phenotypic marker, particularly of severe and therapy-resistant asthma. These early-life events may influence the evolution and be involved in lung function decline. In children, asthma attacks are facilitated by exposure to allergens and pollutants, but are mainly triggered by microbial agents. Multiple studies have assessed immune responses to viruses, and to a lesser extend bacteria, during asthma exacerbation. Research has identified impairment of innate immune responses in children, related to altered pathogen recognition, interferon release, or anti-viral response. Influence of this host-microbiota dialog on the adaptive immune response may be crucial, leading to the development of biased T helper (Th)2 inflammation. These dynamic interactions may impact the presentations of asthma attacks, and have long-term consequences. The aim of this review is to synthesize studies exploring immune mechanisms impairment against viruses and bacteria promoting asthma attacks in children. The potential influence of the nature of infectious agents and/or preexisting microbiota on the development of exacerbation is also addressed. We then discuss our understanding of how these diverse host-microbiota interactions in children may account for the heterogeneity of endotypes and clinical presentations. Finally, improving the knowledge of the pathophysiological processes induced by infections has led to offer new opportunities for the development of preventive or curative therapeutics for acute asthma. A better definition of asthma endotypes associated with precision medicine might lead to substantial progress in the management of severe childhood asthma.

Preventing immediate-onset food allergy in infants, children and adults: Systematic review protocol

BACKGROUND

More than 17 million people across Europe have allergies to food and the burden of food allergies is increasing. In 2014, the European Academy of Allergy and Clinical Immunology (EAACI) published guidelines for preventing food allergy. Important research has been published since then and it is essential to ensure the guidelines reflect the latest evidence. A systematic review will be undertaken to help prepare new guidelines due to be published in 2020.

METHODS

Eleven bibliographic databases will be searched from inception to 31 October 2019 for randomized controlled trials about any intervention designed to prevent the development of new cases of immediate-type/IgE-mediated food allergy in infants, children and adults. There are few randomized controlled trials about the impact of breastfeeding on food allergy so prospective cohort studies about breastfeeding with at least 1000 participants at general risk or 200 at high risk of food allergy will also be eligible. The Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach will be used to assess the certainty of the evidence and tabulate summary data. The risk of bias in individual trials will be assessed using the Cochrane risk of bias tool. All data extraction and quality appraisal will be undertaken independently by two reviewers in partnership with a taskforce of EAACI members.

CONCLUSIONS

Preventing food allergy has the potential to improve personal well-being and reduce societal healthcare costs. It is important that forthcoming European guidelines take the latest research into account. Past reviews have tended to focus on single interventions or combined food allergy with other outcomes, making it difficult to draw robust conclusions about potential impacts for policy and practice.

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.

The Role of Diet Diversity and Diet Indices on Allergy Outcomes

Nutrients in foods are not eaten in isolation and food intake interacts in a complex manner, affecting health and disease outcomes. For this reason, focusing on the whole "pattern" of dietary intake instead of the single nutrients or groups of nutrients when studying diseases outcomes is increasingly appealing and growing. Diet diversity refers to the variety of foods being eaten, and the terms, diversity or variety, are often used interchangeably. When the overall diet is characterized by healthy foods, diet diversity will reflect a diversity/variety of healthy foods eaten over a period of time. The introduction of solid foods in the 1st year of life is considered a measure of increased diet diversity. Consuming a diverse range of foods and food allergens in the first year of life may increase intake of important nutrients and positively affect the gut microbiome structure and function. Intake of omega-3 fatty acids and fibers/prebiotics may be particularly important but more information is required about dose and which individuals are most likely to benefit. Increased diet diversity in the first year of life is also associated with reduced food allergy outcomes. In addition to diet diversity, diet indices are considered measures of overall diet quality and can be used as a simple assessment of dietary intake. The focus of this paper is to review and critically address the current knowledge of the association between diet diversity and diet indices and allergy outcomes. Based on the current evidence, we recommend the introduction of solid foods, including common allergenic solids, during the 1st year of life, according to the infant's neuro-developmental abilities and familial or cultural habits. For infants with severe AD and/or FA, medical assessment may be advisable before introducing common food allergens into the diet. Limited evidence exist about the role of diet indices in pregnancy and allergic disease in the offspring, and the most promising results indicate a reduction in childhood wheeze and/or asthma intake.

Dietary Interventions and Nutritional Factors in the Prevention of Pediatric Asthma

Asthma is the most frequent chronic disease in children, and its pathogenesis involves genetic, epigenetic, and environmental factors. The rapid rise in the prevalence of asthma registered over the last few decades has stressed the need to identify the environmental and modifiable factors associated with the development of the disease. In particular, there is increasing interest in the role of modifiable nutritional factors specific to both the prenatal and post-natal early life as, during this time, the immune system is particularly vulnerable to exogenous interferences. Several dietary factors, including maternal diet during pregnancy, the duration of breastfeeding, the use of special milk formulas, the timing of the introduction of complementary foods, and prenatal and early life supplementation with vitamins and probiotics/prebiotics, have been addressed as potential targets for the prevention of asthma. In this review, we outline recent findings on the potential role of prenatal and perinatal dietary and nutritional interventions for the primary prevention of pediatric asthma. Moreover, we addressed unmet needs and areas for future research in the prevention of childhood-onset asthma.

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.

How does parental history of atopic disease predict the risk of atopic dermatitis in a child? A systematic review and meta-analysis

BACKGROUND

Parental history of atopic disease is a well-established risk factor for the development of atopic dermatitis (AD), but several aspects of this association remain unclear.

OBJECTIVE

We sought to determine the association of parental history of atopic disease with AD in offspring.

METHODS

We searched PubMed and EMBASE through June 2018 for relevant records and adhered to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Pooled odds ratios (ORs) with 95% CI were calculated using random-effects models.

RESULTS

A total of 163 records covering 149 unique studies were included. Of these, 119 studies were included in the meta-analysis. Individuals with parental history of atopic disease had increased odds of AD (OR, 1.81; 95% CI, 1.65-1.99). Parental asthma (OR, 1.56; 95% CI, 1.18-2.05) and allergic rhinitis (OR, 1.68; 95% CI, 1.34-2.11) had a smaller effect than AD (OR, 3.30; 95% CI, 2.46-4.42). The effect of maternal and paternal history was comparable for all atopic diseases. An increase in odds was observed when comparing the effect of having 1 (OR, 1.30; 95% CI, 1.15-1.47) or 2 atopic parents (OR, 2.08; 95% CI, 1.83-2.36), as well as having a parent with 1 (OR, 1.49; 95% CI, 1.28-1.74) or more atopic diseases (OR, 2.32; 95% CI, 1.92-2.81).

CONCLUSIONS

This study provides evidence-based risk estimates that may guide physicians who counsel parents with a history of atopic disease about their children's risk of AD. This information is of particular importance for future efforts toward establishing prophylactic interventions for AD on a general population level.

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.

The Human Microbiota and Asthma

Over the last few decades, advances in our understanding of microbial ecology have allowed us to appreciate the important role of microbial communities in maintaining human health. While much of this research has focused on gut microbes, microbial communities in other body sites and from the environment are increasingly recognized in human disease. Here, we discuss recent advances in our understanding of host-microbiota interactions in the development and manifestation of asthma focusing on three distinct microbial compartments. First, environmental microbes originating from house dust, pets, and farm animals have been linked to asthma pathogenesis, which is often connected to their production of bioactive molecules such as lipopolysaccharide. Second, respiratory microbial communities, including newly appreciated populations of microbes in the lung have been associated with allergic airway inflammation. Current evidence suggests that the presence of particular microbes, especially Streptococcus, Haemophilus, and Morexella species within the airway may shape local immune responses and alter the severity and manifestations of airway inflammation. Third, the gut microbiota has been implicated in both experimental models and clinical studies in predisposing to asthma. There appears to be a "critical window" of colonization that occurs during early infancy in which gut microbial communities shape immune maturation and confer susceptibility to allergic airway inflammation. The mechanisms by which gut microbial communities influence lung immune responses and physiology, the "gut-lung axis," are still being defined but include the altered differentiation of immune cell populations important in asthma and the local production of metabolites that affect distal sites. Together, these findings suggest an intimate association of microbial communities with host immune development and the development of allergic airway inflammation. Improved understanding of these relationships raises the possibility of microbiota-directed therapies to improve or prevent asthma.

Prebiotics: Mechanisms and Preventive Effects in Allergy

Allergic diseases now affect over 30% of individuals in many communities, particularly young children, underscoring the need for effective prevention strategies in early life. These allergic conditions have been linked to environmental and lifestyle changes driving the dysfunction of three interdependent biological systems: microbiota, epithelial barrier and immune system. While this is multifactorial, dietary changes are of particular interest in the altered establishment and maturation of the microbiome, including the associated profile of metabolites that modulate immune development and barrier function. Prebiotics are non-digestible food ingredients that beneficially influence the health of the host by 1) acting as a fermentable substrate for some specific commensal host bacteria leading to the release of short-chain fatty acids in the gut intestinal tract influencing many molecular and cellular processes; 2) acting directly on several compartments and specifically on different patterns of cells (epithelial and immune cells). Nutrients with prebiotic properties are therefore of central interest in allergy prevention for their potential to promote a more tolerogenic environment through these multiple pathways. Both observational studies and experimental models lend further credence to this hypothesis. In this review, we describe both the mechanisms and the therapeutic evidence from preclinical and clinical studies exploring the role of prebiotics in allergy prevention.

What's new in atopic eczema? An analysis of systematic reviews published in 2017. Part 1: treatment and prevention

This review forms part of a series of annual updates that summarize the evidence base for atopic eczema (AE). It provides a summary of key findings from 25 systematic reviews that were published or indexed during 2017, and focuses on the treatment and prevention of AE. There is high-quality evidence to demonstrate that dupilumab is better than placebo for the treatment of AE, is not associated with a higher incidence of adverse effects and does not increase the risk of infection compared with placebo; however, comparison studies with other systemic treatments are necessary. Topical tofacitinib is a promising treatment for mild-moderate AE, but currently lacks sufficient evidence from well-designed randomized controlled trials (RCTs) comparing with other active treatments. Topical doxepin may be effective for pruritus in AE, but available studies have short follow-up periods and longer-term outcomes are needed. Bleach baths were no more effective than water baths alone at reducing AE severity. Topical antibiotics cannot be recommended for infected AE, owing to insufficient evidence of benefit. There is little comparison of different emollients in RCTs, but overall evidence indicates that they reduce AE severity, are steroid-sparing and lead to better outcomes in combination with topical corticosteroids (TCS) than TCS alone. No clear benefit was demonstrated for vitamin D/C/E supplementation in pregnancy for eczema prevention.

The crosstalk between microbiome and asthma: Exploring associations and challenges

With the advancement of high‐throughput DNA/RNA sequencing and computational analysis techniques, commensal bacteria are now considered almost as important as pathological ones. Understanding the interaction between these bacterial microbiota, host and asthma is crucial to reveal their role in asthma pathophysiology. Several airway and/or gut microbiome studies have shown associations between certain bacterial taxa and asthma. However, challenges remain before gained knowledge from these studies can be implemented into clinical practice, such as inconsistency between studies in choosing sampling compartments and/or sequencing approaches, variability of results in asthma studies, and not taking into account medication intake and diet composition especially when investigating gut microbiome. Overcoming those challenges will help to better understand the complex asthma disease process. The therapeutic potential of using pro‐ and prebiotics to prevent or reduce risk of asthma exacerbations requires further investigation. This review will focus on methodological issues regarding setting up a microbiome study, recent developments in asthma bacterial microbiome studies, challenges and future therapeutic potential.

Microbiota and Neurodevelopmental Trajectories: Role of Maternal and Early-Life Nutrition

Pregnancy and early life are characterized by marked changes in body microbial composition. Intriguingly, these changes take place simultaneously with neurodevelopmental plasticity, suggesting a complex dialogue between the microbes that inhabit the gastrointestinal tract and the brain. The purpose of this chapter is to describe the natural trajectory of microbiota during pregnancy and early life, as well as review the literature available on its interaction with neurodevelopment. Several lines of evidence show that the gut microbiota interacts with diet, drugs and stress both prenatally and postnatally. Clinical and preclinical studies are illuminating how these disruptions result in different developmental outcomes. Understanding the role of the microbiota in neurodevelopment may lead to novel approaches to the study of the pathophysiology and treatment of neuropsychiatric disorders.