Vitamin D supplementation in primary allergy prevention: Systematic review of randomized and non-randomized studies

The pathogenesis of food allergy and protection offered by dietary compounds from the perspective of epigenetics

Food allergy is a global food safety concern, with an increasing prevalence in recent decades. However, the immunological and cellular mechanisms involved in allergic reactions remain incompletely understood, which impedes the development of effective prevention and treatment strategies. Current evidence supports those epigenetic modifications regulate the activation of immune cells, and their dysregulation can contribute to the development of food allergies. Patients with food allergy show epigenetic alterations that lead to the onset, duration and recovery of allergic disease. Moreover, many preclinical studies have shown that certain dietary components exert nutriepigenetic effects in changing the course of food allergies. In this review, we provide an up-to-date overview of DNA methylation, noncoding RNA and histone modification, with a focus on their connections to food allergies. Following this, we discuss the epigenetic mechanisms that regulate the activation and differentiation of innate and adapted immune cell in the context of food allergies. Subsequently, this study specifically focuses on the multidimensional epigenetic effects of dietary components in modulating the immune response, which holds promise for preventing food allergies in the future.

Low vitamin D during pregnancy is associated with infantile eczema by up-regulation of PI3K/AKT/mTOR signaling pathway and affecting FOXP3 expression: A bidirectional cohort study

Vitamin D has received increasing attention because of its association with atopic disease development. Limited studies that have been done on the impact of maternal vitamin D levels during pregnancy on infantile eczema are still debatable. We wanted to discover the effect of maternal vitamin D on infantile eczema and explore whether regulatory T cells (Treg) play a role in this process. 219 pairs of mothers and children were enrolled. Maternal fasting venous blood was collected in pregnancy's second and third trimesters to determine vitamin D levels. Cord blood and placenta samples were collected during childbirth for detecting levels of genes, proteins and cytokines. Pediatricians followed up the prevalence of eczema in infants within 1 year. The reported rate of vitamin D deficiency and insufficiency was 35.6% and 28.3%. Lower maternal 25(OH)D3 levels were related to a higher risk of infantile eczema. Foxp3 gene expression is lower in cord blood of infants with eczema compared to infants without eczema. There was a positive correlation between maternal 25(OH)D3 levels and the expression of FOXP3 gene in cord blood. Compared to vitamin D sufficiency women, vitamin D deficiency women's placental FOXP3 protein expression was decreased and PI3K/AKT/mTOR protein was up-regulated. Our study demonstrates that low prenatal maternal vitamin D levels increased the risk of infantile eczema aged 0-1 year, which might be related to the downregulating of the FOXP3 gene expression in cord blood and decreased placental FOXP3 protein expression. Low placental FOXP3 protein was related with activating PI3K/AKT/mTOR signaling pathway.

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.

Insights from the COCOA birth cohort: The origins of childhood allergic diseases and future perspectives

The ongoing COhort for Childhood Origin of Asthma and allergic diseases (COCOA) study is a prospective birth cohort investigating the origin and natural courses of childhood allergic diseases, including atopic dermatitis, food allergy, allergic rhinitis and asthma, with long-term prognosis. Initiated under the premise that allergic diseases result from a complex interplay of immune development alterations, environmental exposures, and host susceptibility, the COCOA study explores these dynamic interactions during prenatal and postnatal periods, framed within the hygiene and microbial hypotheses alongside the developmental origins of health and disease (DOHaD) hypothesis. The scope of the COCOA study extends to genetic predispositions, indoor and outdoor environmental variables affecting mothers and their offsprings such as outdoor and indoor air pollution, psychological factors, diets, and the microbiomes of skin, gut, and airway. We have embarked on in-depth investigations of diverse risk factors and the pathophysiological underpinnings of allergic diseases. By employing multi-omics approaches-proteomics, transcriptomics, and metabolomics-we gain deeper insights into the distinct pathophysiological processes across various endotypes of childhood allergic diseases, incorporating the exposome using extensive resources within the COCOA study. Integration with large-scale datasets, such as national health insurance records, enhances robustness and mitigates potential limitations inherent to birth cohort studies. As part of global networks focused on childhood allergic diseases, the COCOA study fosters collaborative research across multiple cohorts. The findings from the COCOA study are instrumental in informing precision medicine strategies for childhood allergic diseases, underpinning the establishment of disease trajectories.

Nutraceuticals and non-pharmacological remedies for managing patients with allergic rhinitis

Allergic rhinitis (AR) is a common disease characterized by type 2 inflammation and typical symptoms. Although pharmacologic treatment can be effective, prolonged administration of drugs can be associated with adverse reactions and seldom reduction of effectiveness. Therefore, complementary medicine is widespread in clinical practice, mainly in pediatric settings, and pleasing to parents. We reviewed and discussed the most relevant nutraceuticals and non-pharmacological remedies used in managing patients with AR. Nutraceutical, according to Defelice is "a food (or part of a food) that provides medical or health benefits, including the prevention and/or treatment of a disease," and is commonly prescribed by pediatrics as well as self-prescription by parents. There is evidence that some components exert beneficial effects in AR. Some compounds, including micronutrients, vitamins, probiotics, herbal medicines, hyaluronic acid, and saline solutions, could positively and safely be used in children with AR as add-on remedies.

Regulation of Dendritic Cell Functions by Vitamins as Promising Therapeutic Strategy for Immune System Disorders

A functional immune system is crucial for a healthy life, protecting from infections, tumors, or autoimmune disorders; these are accomplished by the interaction between various immune cells. Nourishment, particularly micronutrients, are very important components in the immune system balance, therefore this review emphasizes the vitamins (D, E, A, C) and Dendritic cells' subsets due to vitamins' roles in immune processes, especially on dendritic cells' functions, maturation, and cytokine production. Current studies reveal significant benefits related to vitamins, including vitamin E, which can contribute to the control of dendritic cells' function and maturation. Furthermore, vitamin D plays an immunoregulatory and anti-inflammatory role in the immune system. Metabolite of vitamin A which is called retinoic acid leads to T cells' differentiation to T helper 1 or T helper 17, so low levels of this vitamin exacerbate the menace of infectious diseases, and vitamin C has anti-oxidant effects on dendritic cells and modulate their activation and differentiation program. Additionally, the correlation between the amount of vitamin and the occurrence or progression of allergic diseases and autoimmunity disorders is discussed according to the results of previous studies.

Early-life risk factors for food allergy: Dietary and environmental factors revisited

There appears a steep increase in the prevalence of food allergy worldwide in the past few decades. It is believed that, rather than genetic factors, the recently altered dietary and environmental factors are the driving forces behind the rapid increase of this disease. Accumulating evidence has implied that external exposures that occurred in prenatal and postnatal periods could affect the development of oral tolerance in later life. Understanding the potential risk factors for food allergy would greatly benefit the progress of intervention and therapy. In this review, we present updated knowledge on the dietary and environmental risk factors in early life that have been shown to impact the development of food allergy. These predominantly include dietary habits, microbial exposures, allergen exposure routes, environmental pollutants, and so on. The key evidence, conflicts, and potential research topics of each theory are discussed, and associated interventional strategies to prevent the disease development and ameliorate treatment burden are included. Accumulating evidence has supported the causative role of certain dietary and environmental factors in the establishment of oral tolerance in early life, especially the time of introducing allergenic foods, skin barrier function, and microbial exposures. In addition to certain immunomodulatory factors, increasing interest is raised toward modern dietary patterns, where adequately powered studies are required to identify contributions of those modifiable risk factors. This review broadens our understanding of the connections between diet, environment, and early-life immunity, thus benefiting the progress of intervention and therapy of food allergy.

Distinguishing science from pseudoscience in commercial respiratory interventions: an evidence-based guide for health and exercise professionals

Respiratory function has become a global health priority. Not only is chronic respiratory disease a leading cause of worldwide morbidity and mortality, but the COVID-19 pandemic has heightened attention on respiratory health and the means of enhancing it. Subsequently, and inevitably, the respiratory system has become a target of the multi-trillion-dollar health and wellness industry. Numerous commercial, respiratory-related interventions are now coupled to therapeutic and/or ergogenic claims that vary in their plausibility: from the reasonable to the absurd. Moreover, legitimate and illegitimate claims are often conflated in a wellness space that lacks regulation. The abundance of interventions, the range of potential therapeutic targets in the respiratory system, and the wealth of research that varies in quality, all confound the ability for health and exercise professionals to make informed risk-to-benefit assessments with their patients and clients. This review focuses on numerous commercial interventions that purport to improve respiratory health, including nasal dilators, nasal breathing, and systematized breathing interventions (such as pursed-lips breathing), respiratory muscle training, canned oxygen, nutritional supplements, and inhaled L-menthol. For each intervention we describe the premise, examine the plausibility, and systematically contrast commercial claims against the published literature. The overarching aim is to assist health and exercise professionals to distinguish science from pseudoscience and make pragmatic and safe risk-to-benefit decisions.

Maternal Vitamin D and Inulin Supplementation in Oxidized Oil Diet Improves Growth Performance and Hepatic Innate Immunity in Offspring Mice

Dietary oxidized fat contains harmful materials such as hydrogen peroxide and malondialdehyde (MDA). Excessive oxidized fat intake during pregnancy and lactation not only leads to maternal body injury but also damages offspring health. Our previous study demonstrated that vitamin D (VD) had antioxidative capability in sows. This study was conducted to investigate the effect of maternal VD and inulin supplementation in oxidized oil diet on the growth performance and oxidative stress of their offspring. Sixty 5-month-old C57BL/6N female mice were randomly divided into five groups: Control group (basal diet, n = 12), OF group (oxidized-soybean-oil-replaced diet, n = 12), OFV group (oxidized-soybean-oil-replaced diet + 7000 IU/kg VD, n = 12), OFI group (oxidized-soybean-oil-replaced diet + 5% inulin, n = 12) and OFVI group (oxidized-soybean-oil-replaced diet + 7000 IU/kg VD + 5% inulin, n = 12). Mice were fed with the respective diet during pregnancy and lactation. The offspring were then slaughtered on day 21 of age at weaning. Results showed that a maternal oxidized oil diet impaired body weight and liver weight gain of offspring during lactation compared to the control group, while maternal VD, inulin or VD and inulin mixture supplementation reversed this effect. In addition, the activity of T-AOC in the liver of offspring was lower in the OF group than that in the control group, but could be restored by maternal VD and inulin mixture supplementation. Furthermore, the gene expression of both proinflammatory and anti-inflammatory cytokines, such as Il-6, Tnfα and Il-10, in offspring liver were downregulated by a maternal oxidized oil diet compared with the control group, but they were restored by maternal VD or VD and inulin mixture supplementation. The expressions of Vdr and Cyp27a1 were decreased by a maternal oxidized oil diet compared with the control group, while they could be increased by VD or VD and inulin mixture supplementation. Conclusion: maternal oxidized oil diet intake could impair the growth performance by inducing oxidative stress, but this can be relieved by maternal VD and inulin supplementation.

Beyond allergic progression: From molecules to microbes as barrier modulators in the gut-lung axis functionality

The "epithelial barrier hypothesis" states that a barrier dysfunction can result in allergy development due to tolerance breakdown. This barrier alteration may come from the direct contact of epithelial and immune cells with the allergens, and indirectly, through deleterious effects caused by environmental changes triggered by industrialization, pollution, and changes in the lifestyle. Apart from their protective role, epithelial cells can respond to external factors secreting IL-25 IL-33, and TSLP, provoking the activation of ILC2 cells and a Th2-biased response. Several environmental agents that influence epithelial barrier function, such as allergenic proteases, food additives or certain xenobiotics are reviewed in this paper. In addition, dietary factors that influence the allergenic response in a positive or negative way will be also described here. Finally, we discuss how the gut microbiota, its composition, and microbe-derived metabolites, such as short-chain fatty acids, alter not only the gut but also the integrity of distant epithelial barriers, focusing this review on the gut-lung axis.

Evaluating the effects of vitamin D Level on airway obstruction in two asthma endotypes in humans and in two mouse models with different intake of vitamin D during early-life

Introduction

Asthma is primarily divided into two categories: type 2 (T2-high) and non-type 2 (T2-low). A relationship between asthma severity and vitamin D deficiency has been identified, but its impact on each asthma endotype remains unknown.

Methods

We clinically examined the influence of vitamin D on patients with T2-high (n = 60) or T2-low asthma (n = 36) compared with controls (n = 40). Serum 25(OH)D levels, inflammatory cytokines and spirometry were measured. Mouse models were then used to further analyze the effects of vitamin D on both asthmatic endotypes. BALB/c mice were fed with vitamin D-deficient (LVD), -sufficient (NVD), or -supplemented diets (HVD) throughout lactation and offspring followed the same diet after weaning. Offspring were sensitized/challenged with ovalbumin (OVA) to establish "T2-high" asthma or OVA combined with ozone exposure (OVA + ozone) to induce "T2-low" asthma. Spirometry and serum, bronchoalveolar lavage fluid (BALF), and lung tissues were analyzed.

Results

Serum 25(OH)D levels were decreased in asthmatic patients compared with controls. Patients with vitamin D deficiency (Lo) had varying degrees of elevation of the pro-inflammatory cytokines IL-5, IL-6, and IL-17A, decreased expression of the anti-inflammatory cytokine IL-10, and altered forced expiratory volume in the first second as a percentage of predicted value (FEV₁%pred) in both asthmatic endotypes. Vitamin D status had a stronger correlation with FEV₁%pred in T2-low asthma than T2-high asthma, and 25(OH)D level was only positively linked to maximal mid-expiratory flow as a percentage of predicted value (MMEF%pred) in the T2-low group. Inflammation, hyperresponsiveness, and airway resistance (R_L) was increased in both asthma models compared with controls while vitamin D deficiency further increased airway inflammation and airway obstruction. These findings were particularly prominent in T2-low asthma.

Discussion

The potential function and mechanisms of vitamin D and both asthma endotypes should be studied individually, and further analysis of the potential signaling pathways involved with vitamin D on T2-low asthma is warranted.

Nutritional management of food allergies: Prevention and treatment

An individualized allergen avoidance plan is the cornerstone of the nutritional management of food allergy (FA). In pediatric age, the main objective is preventing the occurrence of acute and chronic symptoms by avoiding the offending food(s) and providing an adequate, nutritionally balanced and personalized diet at the same time. For this reason, the presence of a trained dietitian is recommended in order to meet nutritional needs of patients with FA and to provide a tailored nutritional plan, minimizing the impact of FA on quality of life and maintaining optimal growth.

The Crosstalk between Vitamin D and Pediatric Digestive Disorders

Vitamin D is a cyclopentane polyhydrophenanthrene compound involved mainly in bone health and calcium metabolism but also autophagy, modulation of the gut microbiota, cell proliferation, immune functions and intestinal barrier integrity. The sources of vitamin D include sunlight, diet and vitamin D supplements. Vitamin D3, the most effective vitamin D isoform is produced in the human epidermis as a result of sunlight exposure. Vitamin D undergoes two hydroxylation reactions in the liver and kidney to reach its active form, 1,25-dihydroxyvitamin D. Recent studies highlighted a complex spectrum of roles regarding the wellbeing of the gastrointestinal tract. Based on its antimicrobial effect, it was recently indicated that vitamin D supplementation in addition to standard eradication therapy might enhance H. pylori eradication rates. Moreover, it was suggested that low levels of vitamin D might also be involved in the acquisition of H. pylori infection. In terms of celiac disease, the negative effects of vitamin D deficiency might begin even during intrauterine life in the setting of maternal deficiency. Moreover, vitamin D is strongly related to the integrity of the gut barrier, which represents the core of the pathophysiology of celiac disease onset, in addition to being correlated with the histological findings of disease severity. The relationship between vitamin D and cystic fibrosis is supported by the involvement of this micronutrient in preserving lung function by clearing airway inflammation and preventing pathogen airway colonization. Moreover, this micronutrient might exert anticatabolic effects in CF patients. Inflammatory bowel disease patients also experience major benefits if they have a sufficient level of circulating vitamin D, proving its involvement in both induction and remission in these patients. The findings regarding the relationship between vitamin D, food allergies, diarrhea and constipation remain controversial, but vitamin D levels should be monitored in these patients in order to avoid hypo- and hypervitaminosis. Further studies are required to fill the remaining gaps in term of the complex impact of vitamin D on gastrointestinal homeostasis.

Dietary Factors Associated with Asthma Development: A Narrative Review and Summary of Current Guidelines and Recommendations

Asthma is a complex disease, caused by a combination of genetic and environmental factors. The prevalence of asthma is increasing too rapidly to be attributable to genetic factors alone. Thus, environmental factors are becoming increasingly recognized as the cause of asthma. Modifying these environmental factors may be a simple approach for asthma prevention. To date, dietary intervention is an interesting modifiable factor because it can be implemented at the population level. The modification of systemic inflammation, oxidation, and microbial composition might be a mechanistic basis for prevention. This review summarizes the mechanistic basis and evidence from clinical studies on the association between dietary factors and asthma development. We also summarize the recommendations from many organizations and regional guidelines to assist the practicing physician to improve patient care.

A pragmatic approach to infant feeding for food allergy prevention

Early introduction of allergenic foods into an infant's diet is currently the most promising strategy to prevent food allergy, with infant guidelines around the world shifting from promoting avoidance to actively encourage the introduction of allergenic foods in the infant diet. Infant feeding guidelines vary according to regional public health priorities, and knowledge gaps remain, resulting in ongoing challenges for clinicians and families to translate guidelines into practical strategies for the introduction of complementary foods for food allergy prevention. Evidence from Australia demonstrates high community support and uptake of revised guidelines with most parents introducing allergenic foods in the first year of life, although this has not had the expected impact on substantially reducing food allergy prevalence. To uptake of guidelines from other countries is less clear, and several barriers have been noted in infant feeding RCTs, which may warrant intervention strategies. Further research is needed to understand additional strategies for food allergy prevention, particularly in infants who develop food allergy prior to when they are developmentally ready to commence solids. Several RCTs are underway investigating preventative strategies that target the window before allergen ingestion, such as vitamin D supplementation, emollient use, and immunizations that prime the immune response away from a Th2-driven allergic phenotype. Further research is also needed to understand the role of the environment and the host environment in the development of tolerance to foods.

Mast Cells and Vitamin D Status: A Clinical and Biological Link in the Onset of Allergy and Bone Diseases

The immune system is made up by an extremely composite group of cells, whose regulated and harmonious activity is fundamental to maintain health. The mast cells are an essential effector of inflammatory response which is characterized by a massive release of mediators accumulated in cytoplasmic secretory granules. However, beyond the effects on immune response, mast cells can modify bone metabolism and are capable of intervening in the genesis of pathologies such as osteoporosis and osteopenia. Vitamin D is recognized to induce changes in bone metabolism, but it is also able to influence immune response, suppressing mast cell activation and IgE synthesis from B cells and increasing the number of dendritic cells and IL-10-generating regulatory T cells. Vitamin D deficit has been reported to worsen sensitization and allergic manifestations in several different experimental models. However, in clinical situations, contradictory findings have been described concerning the correlation between allergy and vitamin D deficit. The aim of this review was to analyze the close relationships between mast cells and vitamin D, which contribute, through the activation of different molecular or cellular activation pathways, to the determination of bone pathologies and the onset of allergic diseases.

Taiwan guidelines for the diagnosis and management of pediatric atopic dermatitis: Consensus statement of the Taiwan Academy of Pediatric Allergy, Asthma and Immunology

Atopic dermatitis (also known as atopic eczema) is a chronic relapsing inflammatory skin disease commonly seen in children, with increasing prevalence over the past few decades in many countries including Taiwan. The management of pediatric atopic dermatitis can be challenging, particularly as treatment options are expanding with the emergence of novel systemic and topical anti-inflammatory medications in recent years. The Taiwan Academy of Pediatric Allergy, Asthma and Immunology (TAPAAI) has developed the Taiwan guidelines for the diagnosis and management of pediatric atopic dermatitis, which provides a concise overview of its epidemiology, clinical characteristics and diagnosis, mechanisms, treatments, and education. The contents of this guideline integrate the principles of recent national and international guidelines for the diagnosis and management of atopic dermatitis, latest research findings, and expert opinions of experienced pediatric allergy specialists in Taiwan. For practical purposes, this guideline presents simplified and easy-to-use diagnostic criteria and severity grading for pediatric atopic dermatitis. A stepwise treatment algorithm is also proposed to expedite rational, cost-effective, and evidence-based management strategy. This guideline, developed based on current best evidence and real-world experience of pediatric allergy experts in Taiwan, is intended to facilitate practical, up-to-date management of pediatric atopic dermatitis among physicians.

A Novel Strategy for the Treatment of Allergic Rhinitis: Regulating Treg/Th17 and Th1/Th2 Balance In Vivo by Vitamin D

Objective

This prospective study is aimed at observing the number of nasal itching and sneezing in rats from the macroscopic level and examine the pathological changes of nasal mucosa, Th1 and Th2-related cytokines, and Treg/Th17 by vitamin D3 administration from the microscopic level, in order to explore the role of vitamin D in allergic rhinitis and to provide theoretical guidance for prevention and treatment.

Results

There were significant differences in nasal itching and sneezing between the administration groups and the positive groups. Meanwhile, the level of Th1 and Treg in the administration groups increased, while the level of Th2 and Th17 decreased, indicating that the balance of Th1/Th2 was corrected. Our study revealed that vitamin D3 has preventive and therapeutic effects on allergic rhinitis, which provides theoretical guidance for practical application.

The role of prenatal vitamin D on the development of childhood asthma and wheeze: An umbrella review of systematic reviews and meta-analyses

BACKGROUND & OBJECTIVE

It has been suggested that prenatal vitamin D plays a role in the development of childhood asthma and wheeze. Several systematic reviews have been conducted, but the results are inconsistent, and the methodological quality has not been studied. Therefore, the objective of this umbrella review was to assess the internal validity of the evidence base and the evidence for an association between prenatal vitamin D and asthma or wheezing in the offspring.

METHODS

We searched the electronic databases Embase, PubMed, and Cochrane Library for studies on prenatal vitamin D using search words such as vitamin D, 25-hydroxyvitamin D, calcidiol, fetal, and neonatal. The search was conducted in June 2020, and the databases were searched from their date of establishment. We included systematic reviews and/or meta-analyses of experimental and observational studies assessing the association between prenatal vitamin D or asthma and wheeze. We excluded narrative reviews, commentaries, and other umbrella reviews. The methodological quality of systematic reviews was assessed using AMSTAR 2 tool. PROSPERO reg. no. CRD42020151329.

RESULTS

We identified 22 eligible systematic reviews (17 on asthma and 20 on wheeze). Using the AMSTAR 2 quality assessment tool, the methodological quality was rated as critically low in 21 out of 22 systematic reviews, suggesting that previous reviews and meta-analyses did not provide accurate and comprehensive summaries of the included studies and that conclusions reached were potentially flawed. The majority of the included reviews reported that prenatal vitamin D reduces the risk of wheeze in the offspring.

CONCLUSION

Prior to informing public guidelines, high-quality systematic reviews of the current evidence are greatly warranted.

Cord blood 25(OH)D3, cord blood total immunoglobulin E levels, and food allergies in infancy: A birth cohort study in Chongqing, China

Background

Food allergy (FA) in infants has become a common disease worldwide. There are many controversies surrounding the relationships among levels of cord blood 25-hydroxy vitamin D3 [25(OH)D3], total immunoglobulin E (IgE), and FA.

Methods

In this study, we recruited pregnant women in the third trimester undergoing obstetric examination in Chongqing City, Western China. Healthy full-term singleton births between May to August 2018 and November 2018 to January 2019 were included in the summer-birth and winter-birth cohorts, respectively. Questionnaires on vitamin D status in pregnancy and family allergies were used to investigate the pregnant women. The levels of <12 ng/mL, 12～20 ng/mL, and >20 ng/mL 25(OH)D3 in cord blood detected by liquid chromatography tandem mass spectrometry were considered deficient, insufficient, and sufficient, respectively. The electrochemiluminescence method was used to detect the total lgE levels in cord blood, classified into low-IgE (<0.35 IU/mL) and high-IgE (≥0.35 IU/mL) levels, respectively. Within postnatal 6 months, allergic symptoms in infants were investigated using questionnaire during the infants' monthly physical examinations. Suspected cases of FA underwent a history inquiry, skin prick test, food elimination test, and open-food challenge for diagnosis of FA. Multivariate logistic regression was used to analyze the risk factors of FA in infants.

Results

In this study, we recruited 741 pairs of pregnant women and infants, including 343 infants in the summer-birth cohort and 398 infants in the winter-birth cohort. The incidence of FA within postnatal 6 months was 6.88%, showing significantly higher incidence of FA in the winter-birth cohorts than in the summer-birth cohorts (10.3% vs. 2.9%, χ2 = 15.682, P = 0.000). Among the 741 infants, 47.1%, 27.5%, and 13.8% of infants had deficient, insufficient, and sufficient 25(OH)D3, respectively, in the cord blood; 81.5% and 18.5% of infants had total low-IgE and total high-IgE levels, respectively, in the cord blood. No significant correlation was found between the 25(OH)D3 and IgE levels (r = -0.038, P = 0.300). Logistic regression analysis showed that winter birth [odds ratio (OR) 95% confidence interval (CI): 4.292 (2.003～8.359)] compared with infants in summer birth group, and sufficient (>20 ng/mL) 25(OH)D3 levels in cord blood [OR (95% CI): 2.355 (1.129～4.911) compared with infants in the deficient group (<12 ng/mL) and 3.782 (1.680～8.514) compared with infants in the insufficient group (12～20 ng/mL)] were independent risk factors for FA in infants within postnatal 6 months.

Conclusions

Winter birth and sufficient 25(OH)D3 levels in infant cord blood were independent risk factors for FA in infants. 25(OH)D3 and total IgE levels in cord blood cannot be used as predictors of FA in early infancy.

Role of the dietary components in food allergy: A comprehensive review

Currently, the increasing incidence of food allergy is considered a major public health and food safety concern. Importantly, food-induced anaphylaxis is an acute, life-threatening, systemic reaction with varied clinical presentations and severity that results from the release of mediators from mast cells and basophils. Many factors are blamed for the increasing incidence of food allergy, including hygiene, microbiota (composition and diversity), inopportune complementary foods (a high-fat diet), and increasing processed food consumption. Studies have shown that different food components, including lipids, sugars, polyphenols, and vitamins, can modify the immunostimulating properties of allergenic proteins and change their bioavailability. Understanding the role of the food components in allergy might improve diagnosis, treatment, and prevention of food allergy. This review considers the role of the dietary components, including lipids, sugars, polyphenols, and vitamins, in the development of food allergy as well as results of mechanistic investigations in in vivo and in vitro models.

Associations between child filaggrin mutations and maternal diet with the development of allergic diseases in children

BACKGROUND

Filaggrin (FLG) loss-of-function mutations in children and maternal diet in pregnancy have been implicated in child allergy outcomes. This paper studies the questions: "do FLG mutations modify the effect of maternal diet on the odds of development of allergic diseases?" and "which factor leads to the highest rate of diagnosis allergic diseases over time, maternal diet, or FLG mutations?".

METHODS

Exact logistic regressions studied effect modification. Cox proportional hazard models compared the rate of allergic disease development in three groups (N = 624): (1) children with FLG mutation, (2) children without FLG mutation whose mothers did not eat an allergy preventive diet, and (3) children without FLG mutation whose mothers ate an allergy preventive diet. Maternal diet was classified using a validated index.

RESULTS

Cox models showed the development of atopic dermatitis, asthma, and wheeze was significantly higher for children in group 1 versus 3 (HR = 2.40 [1.32, 4.37], HR = 2.29 [1.05, 4.97], and HR 2.10 [1.004, 4.38], respectively), but not significantly higher for children in group 1 versus 2 (HR = 1.30 [0.74, 2.29], HR = 1.27 [0.61, 2.63], and HR = 1.29 [0.65, 2.58], respectively). Development of allergic rhinitis was significantly higher for group 1 versus 2 and 3 (1 vs. 2: HR = 2.29 [1.10, 4.76]; 1 vs. 3: HR = 3.21 [1.46, 7.08]). There was no significant effect modification for any outcome.

CONCLUSION

Children with FLG mutation had similar risk of atopic dermatitis, asthma, and wheeze as children without an FLG mutation whose mothers did not eat an allergy preventive diet during pregnancy. Child FLG mutation did not modify the effect of maternal diet. The results suggest that maternal diet in pregnancy, a modifiable risk factor, could be a target for preventive interventions.

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.

Vitamin D supplementation in pregnant women or infants for preventing allergic diseases

Background:

It is still unclear if and to what extent antenatal or infant or childhood vitamin D supplementation would affect the development of allergy diseases later in life. This study aimed to review the efficacy of vitamin D supplementation in pregnant women, infants, or children for the prevention of allergies.

Methods:

MEDLINE (PubMed), EMBASE (OVID), and the Cochrane Central Register of Controlled Trials were searched up to March 1, 2020. We included only randomized controlled trials (RCTs). We performed a systematic review and meta-analysis for vitamin D supplementation in primary allergy prevention. These trials were assessed for risk of bias using the Cochrane Collaboration domains and the consensus was reached via discussion with the full study group. We descriptively summarized and quantitatively synthesized original data to evaluate vitamin D supplementation in primary allergy prevention by using Review Manager software for meta-analysis.

Results:

The search yielded 1251 studies. Seven RCTs were included in this analysis. A meta-analysis revealed that vitamin D supplementation for pregnant women or infants may not decrease the risk of developing allergic diseases, such as asthma or wheezing (supplementation for pregnant women, risk ratio [RR]: 1.01, 95% confidence interval [CI]: 0.81–1.26, P = 0.90, I² = 47%; supplementation for infants, RR: 1.00, 95% CI: 0.70–1.43, P = 0.99, I² = 0%; supplementation for pregnant women and infants, RR: 0.35, 95% CI: 0.10–1.25, P = 0.11), eczema (supplementation for pregnant women, RR: 0.95, 95% CI: 0.80–1.13, P = 0.77, I² = 0%; supplementation for infants, RR: 0.84, 95% CI: 0.64–1.11, P = 0.19, I² = 42%), allergic rhinitis (supplementation for pregnant women, RR: 0.93, 95% CI: 0.78–1.11, P = 0.15, I² = 47%), lower respiratory tract infection (LRTI) (supplementation for pregnant women, RR: 0.97, 95% CI: 0.85–1.11, P = 0.59, I² = 0%), or food allergy.

Conclusions:

Supplementation of vitamin D in pregnant women or infants does not have an effect on the primary prevention of allergic diseases.

Systematic Review Registration:

PROSPERO (CRD42020167747)

An Overview of Environmental Risk Factors for Food Allergy

IgE-mediated food allergy is an increasing public health concern in many regions around the world. Although genetics play a role in the development of food allergy, the reported increase has occurred largely within a single generation and therefore it is unlikely that this can be accounted for by changes in the human genome. Environmental factors must play a key role. While there is strong evidence to support the early introduction of allergenic solids to prevent food allergy, this is unlikely to be sufficient to prevent all food allergy. The purpose of this review is to summarize the evidence on risk factors for food allergy with a focus the outdoor physical environment. We discuss emerging evidence of mechanisms that could explain a role for vitamin D, air pollution, environmental greenness, and pollen exposure in the development of food allergy. We also describe the recent extension of the dual allergen exposure hypothesis to potentially include the respiratory epithelial barrier in addition to the skin. Few existing studies have examined the relationship between these environmental factors with objective measures of IgE-mediated food allergy and further research in this area is needed. Future research also needs to consider the complex interplay between multiple environmental factors.

Early Oral Nutritional Supplements in the Prevention of Wheezing, Asthma, and Respiratory Infections

Wheezing, asthma, and respiratory infections (RTI) are among the most common causes of morbidity in children and their economic and social burden could be significantly reduced by specific prevention strategies. Epidemiological studies suggest that lower levels of some nutrients are associated with higher prevalence of these conditions, but the possible protective effect of early supplementation with these nutrients has not yet been established. Aim of our review is to synthetize the available scientific evidence on the role of supplementation with pre- and probiotics, vitamin D, fish and poly-unsaturated fatty acids (PUFA), vitamin A, C, and E, given during the first year of life, in the prevention of wheezing, asthma and RTI. We searched studies published on this topic in the PubMed database between January 2000 and September 2021. As for pre- and probiotics, most of the studies showed that an early supplementation had no protective effect toward the development of asthma and wheezing, while conflicting results were reported on their role in the reduction of RTI. As for vitamin D, the available data suggest that early and regular (on a daily or weekly base) supplementation of vitamin D during infancy could have a role in the prevention of RTI, while most studies showed no effect in the prevention of wheezing or asthma. Finally, early introduction of fish in the diet in most studies has proved protective toward wheezing and asthma development.

Primary prevention of food allergy in 2021: Update and proposals of French-speaking pediatric allergists

During the past years, there has been an alarming increase in cases of food allergy and anaphylaxis in ever-younger children. Often, these children have multiple food allergies and food sensitizations, involving allergens with high anaphylactic potential, such as peanuts and nuts, which have a major influence on their quality of life and future. After reviewing the current epidemiological data, we discuss the main causes of the increase in food allergies. We analyze data from studies on the skin barrier and its fundamental role in the development of sensitization and food allergies, data on the tolerogenic digestive tract applied in particular to hen eggs and peanuts, as well as data on the prevention of allergy to cow milk proteins. In light of these studies, we propose a practical guide of recommendations focused on infants and the introduction of cow milk, the management of eczema, and early and broad dietary diversification including high-risk food allergens, such as peanut and nuts while taking into account the food consumption habits of the family.

What are the highest yielding search strategy terms for systematic reviews in atopic dermatitis? A systematic review

The impact of search strategies on systematic reviews (SR) of atopic dermatitis (AD) is unknown. The purpose of this review was to evaluate search strategies used in SR of AD and their impact on the frequency of manuscripts identified. MEDLINE and EMBASE were searched for SR related to AD. Simulations were performed by running combinations of search terms in MEDLINE and EMBASE. Overall, 250 SR met inclusion criteria, of which 225 specified search strategies. SR using 5-6 terms (20.0% to 12.1%) or ≥ 7 (40.0% to 18.8%) terms decreased, whereas SR using 3-4 terms numerically increased (18.8% to 30.2%) and 1-2 terms remained similar (37.5% to 38.9%) from 1999-2009 to 2015-2019. The most commonly searched terms were "atopic dermatitis" (n = 166), followed by "eczema" (n = 156), "dermatitis atopic'" (n = 81), "atopic eczema" (n = 74), "neurodermatitis" (n = 59), "Besniers prurigo" (n = 29), "infantile eczema" (n = 27), and "childhood eczema" (n = 19). Simulations revealed that "eczema" and "atopic dermatitis" yielded the most hits. The number of search terms that maximized hits in MEDLINE and EMBASE was 5 and 4, respectively. Search strategies for AD were heterogeneous, with high proportions of search strategies providing few search hits. Future studies should use standardized and optimized search terms.

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.

Potential Biomarkers, Risk Factors and their Associations with IgE-mediated Food Allergy in Early Life: A Narrative Review

Food allergy affects the quality of life of millions of people worldwide and presents a significant psychological and financial burden for both national and international public health. In the past few decades, the prevalence of allergic disease has been on the rise worldwide. Identified risk factors for food allergy include family history, mode of delivery, variations in infant feeding practices, prior diagnosis of other atopic diseases such as eczema, and social economic status. Identifying reliable biomarkers which predict the risk of developing food allergy in early life would be valuable in both preventing morbidity and mortality and by making current interventions available at the earliest opportunity. There is also the potential to identify new therapeutic targets. This narrative review provides details on the genetic, epigenetic, dietary and microbiome influences upon the development of food allergy and synthesizes the currently available data indicating potential biomarkers. While there is a large body of research evidence available within each field of potential risk factors, there are very limited number of studies which span multiple methodological fields, for example including immunology, microbiome, genetic/epigenetic factors and dietary assessment. We recommend that further collaborative research with detailed cohort phenotyping is required to identify biomarkers, and whether these vary between at-risk populations and the wider population. The low incidence of oral food challenge confirmed food allergy in the general population, and the complexities of designing nutritional intervention studies will provide challenges for researchers to address in generating high quality, reliable and reproducible research findings.

STATEMENT OF SIGNIFICANCE

Food allergy affects the quality of life of millions of people worldwide and presents a significant psychological and financial burden for both national and international public health. Identifying reliable biomarkers which predict the risk of developing food allergy would be valuable in both preventing morbidity and mortality and by making current interventions available at the earliest opportunity. This review provides details on the genetic, epigenetic, dietary and microbiome influences upon the development of food allergy. This helps in identifying reliable biomarkers to predict the risk of developing food allergy, which could be valuable in both preventing morbidity and mortality and by making interventions available at the earliest opportunity.

Monitored Supplementation of Vitamin D in Preterm Infants: A Randomized Controlled Trial

Appropriate supplementation of vitamin D can affect infections, allergy, and mental and behavioral development. This study aimed to assess the effectiveness of monitored vitamin D supplementation in a population of preterm infants. 109 preterm infants (24 0/7–32 6/7 weeks of gestation) were randomized to receive 500 IU vitamin D standard therapy (n = 55; approximately 800–1000 IU from combined sources) or monitored therapy (n = 54; with an option of dose modification). 25-hydroxyvitamin D [25(OH)D] concentrations were measured at birth, 4 weeks of age, and 35, 40, and 52 ± 2 weeks of post-conceptional age (PCA). Vitamin D supplementation was discontinued in 23% of infants subjected to standard treatment due to increased potentially toxic 25(OH)D concentrations (>90 ng/mL) at 40 weeks of PCA. A significantly higher infants’ percentage in the monitored group had safe vitamin D levels (20–80 ng/mL) at 52 weeks of PCA (p = 0.017). We observed increased vitamin D levels and abnormal ultrasound findings in five infants. Biochemical markers of vitamin D toxicity were observed in two patients at 52 weeks of PCA in the control group. Inadequate and excessive amounts of vitamin D can lead to serious health problems. Supplementation with 800–1000 IU of vitamin D prevents deficiency and should be monitored to avoid overdose.

Vitamin D3 Enriches Ceramide Content in Exosomes Released by Embryonic Hippocampal Cells

The release of exosomes can lead to cell–cell communication. Nutrients such as vitamin D3 and sphingolipids have important roles in many cellular functions, including proliferation, differentiation, senescence, and cancer. However, the specific composition of sphingolipids in exosomes and their changes induced by vitamin D3 treatment have not been elucidated. Here, we initially observed neutral sphingomyelinase and vitamin D receptors in exosomes released from HN9.10 embryonic hippocampal cells. Using ultrafast liquid chromatography tandem mass spectrometry, we showed that exosomes are rich in sphingomyelin species compared to whole cells. To interrogate the possible functions of vitamin D3, we established the optimal conditions of cell treatment and we analyzed exosome composition. Vitamin D3 was identified as responsible for the vitamin D receptor loss, for the increase in neutral sphingomyelinase content and sphingomyelin changes. As a consequence, the generation of ceramide upon vitamin D3 treatment was evident. Incubation of the cells with neutral sphingomyelinase, or the same concentration of ceramide produced in exosomes was necessary and sufficient to stimulate embryonic hippocampal cell differentiation, as vitamin D3. This is the first time that exosome ceramide is interrogated for mediate the effect of vitamin D3 in inducing cell differentiation.

Association between vitamin D status and allergen sensitization in pediatric subjects in the Balearic Islands

INTRODUCTION

Vitamin D has known effects on the immune system, and its deficiency has been associated with allergen sensitization.

MATERIAL AND METHODS

A retrospective study was performed to evaluate the association between 25(OH)vitamin D (25(OH)D) and specific IgE for the most frequent allergens in our area in children and adolescents. All subjects under 15 years of age with a determination of Phadiatop^® or Phadiatop Infant^® and close serum 25(OH)D determination were included, from 2012 to 2019. From this sample, demographic and analytical variables were collected: specific IgE to Dermatophagoides pteronyssinus; dog and cat dander; grass, olive, and pellitory pollens; egg white; and cow milk; as well as complete blood count analysis and immunoglobulins.

RESULTS

A total of 749 subjects were recruited. Clusters according to deficiency, insufficiency, or sufficiency of 25(OH)D showed an association with age, Phadiatop^® , D. pteronyssinus, cat and dog dander specific IgE, and a higher frequency of positive allergen sensitization (P < .05). Logistic regression, compared with vitamin D levels of greater than 30 ng/mL after age adjustment, showed that deficient 25(OH)D was associated with D. pteronyssinus (OR 1.90; 95% CI, 1.25-2.90) and dog dander (OR, 2.10; 1.10-4.02); whereas insufficient 25(OH)D was associated with cat dander (OR, 2.46; 1.15-5.28) and also with D. pteronyssinus (OR, 1.55; 1.06-2.29) (P < .05). No associations were found between 25(OH) D levels and other analytical parameters.

CONCLUSION

Vitamin D status is associated with sensitization to D. pteronyssinus, and cat and dog dander in children and adolescents, and also with a higher number of positive specific IgE.

Effective Ways to Prevent Allergic Diseases: Where Do We Stand?

Since allergic diseases are of great public health relevance, effective primary prevention strategies are urgently needed. This chapter gives an overview of existing primary prevention programs on environmental exposures and dietary strategies based on epidemiological studies which have defined risk- and protective factors for the development of allergic diseases.The allergy protective effect mediated by growing up on a traditional farm environment is well studied. But the exact underlying mechanisms have still not been fully clarified and have not yet led to concrete prevention strategies. The beneficial effect of avoiding cigarette smoke exposure, indoor moisture and molds in pregnancy and childhood on the development of asthma is well documented. Whereas the avoidance of house dust mite exposure is not recommended to prevent eczema or allergy. Dietary supplementation with vitamins, pre- and probiotics in pregnant woman and their offspring is not harmful but evidence for the prevention of allergic diseases is still lacking. Fish oil consumption was shown to be asthma protective. The early introduction of peanuts and egg protein to prevent peanut and egg allergy in children with atopic dermatitis is promising. Further studies are needed to increase the overall evidence in allergy prevention. Most studies lack methodological standards such as randomization and blinding. More evidence is in demand on the potential beneficial impact of multifaceted interventional studies. The future of allergy prevention strategies might be based on individual risk assessment. Therefore, research in the immunological and molecular basis of allergic diseases needs to be promoted.

Vitamin D: can the sun stop the atopic epidemic?

PURPOSE OF REVIEW

To review recent evidence on the capacity of vitamin D to prevent atopic disease, focussing on food allergy and asthma, and potential underlying mechanisms.

RECENT FINDINGS

The incidence of allergic disease continues to increase worldwide. Vitamin D status is influenced by sun exposure and dietary intake. Vitamin D deficiency is linked to an increased incidence of allergic disease and asthma. These associations are generally strongest in early life. The capacity of vitamin D to enhance antimicrobial pathways, promote peripheral immunological tolerance and maintain mucosal barrier integrity may underlie these associations. Interventional studies have addressed the capacity of vitamin D supplementation in utero and early life to reduce the incidence of disease. Ancillary studies have provided insights into potential biological mechanisms linked to these effects.

SUMMARY

Observational studies show an inverse association between vitamin D levels and development of food allergy and asthma. Secondary analyses of two recent interventional studies suggest that achieving vitamin D sufficiency throughout pregnancy reduces the incidence of asthma/recurrent wheeze at 3 years. Longitudinal studies of vitamin D requirements in utero and postnatally, better understanding of factors that influence bioavailability of vitamin D and mechanistic insights into vitamin D effects on neonatal-specific immune pathways are awaited.

Halting the March: Primary Prevention of Atopic Dermatitis and Food Allergies

Atopic dermatitis (AD) is one of the most common inflammatory skin conditions, affecting 15% to 30% of children and 2% to 10% of adults. Population-based studies suggest that having AD is associated with subsequent development of other atopic diseases, in what is known as the "atopic march." We will provide an overview of studies that investigate primary prevention strategies for the first 2 diseases in the march, namely, AD and food allergies (FA). These strategies include emollients, breastfeeding, microbial exposures, probiotics, vitamin D and UV light, water hardness, and immunotherapy. Some studies, including randomized controlled trials on emollients and microbial supplementation, have found encouraging results; however, the evidence remains limited and contradictory. With regard to breastfeeding, microbial and lifestyle exposures, vitamin D and UV light, water hardness, and immunotherapy, the lack of randomized controlled trials makes it difficult to draw definitive conclusions. Current American Academy of Pediatrics guidelines support the idea that breastfeeding for 3 to 4 months can decrease AD incidence in children less than 2 years old. Recommendations regarding a direct relationship between breastfeeding on FA, however, cannot be made because of insufficient data. Regarding microbial supplementation, most guidelines do not recommend probiotics or prebiotics for the purpose of preventing allergic diseases because of limited evidence. Before definitive conclusions can be made regarding these interventions, more well-designed, longitudinal, and randomized controlled trials, particularly in at-risk populations, are required.

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.

Maternal and Cord Blood 25-Hydroxyvitamin D3 Are Associated with Increased Cord Blood and Naive and Activated Regulatory T Cells: The Barwon Infant Study

Vitamin D has shown immune-modulatory effects but mostly in in vitro and animal studies. Regulatory T cells (Treg) are important for a balanced immune system. The relationship between vitamin D on the number of circulating neonatal Treg is unclear. We sought to investigate the association between maternal and neonatal vitamin D metabolites and cord blood (CB) Treg subsets. In a cohort of Australian infants (n = 1074), recruited using an unselected antenatal sampling frame, 158 mother-infant pairs had data on the following: 1) 25-hydroxyvitamin D₃ (25(OH)D₃) measures in both maternal peripheral blood (28- to 32-wk gestation) and infant CB; 2) proportions (percentage of CD4⁺ T cells) of CB Treg subsets (CD4⁺CD45RA⁺ FOXP3^low naive Treg, and CD4⁺CD45RA^- FOXP3^high activated Treg [aTreg]); and 3) possible confounders, including maternal personal UV radiation. Multiple regression analyses were used. The median 25(OH)D₃ was 85.4 and 50.7 nmol/l for maternal and CB samples, respectively. Higher maternal 25(OH)D₃ levels were associated with increased CB naive Treg (relative adjusted mean difference [AMD] per 25 nmol/l increase: 5%; 95% confidence interval [CI]: 1-9%), and aTreg (AMD per 25 nmol/l increase: 17%; 95% CI: 6-28%). Furthermore, a positive association between CB 25(OH)D₃ levels and CB aTreg (AMD per 25 nmol/l increase: 29%; 95% CI: 13-48%) was also evident. These results persisted after adjustment for other factors such as maternal personal UV radiation and season of birth. 25(OH)D_3, may play a role in the adaptive neonatal immune system via induction of FOXP3⁺ Tregs. Further studies of immune priming actions of antenatal 25(OH)D₃ are warranted.

Prevention of food allergy: can we stop the rise of IgE mediated food allergies?

PURPOSE OF REVIEW

Food allergy has become more prevalent in recent decades. Without a curative treatment for food allergy, prevention is key. Can we intervene and halt the food allergy epidemic?

RECENT FINDINGS

There are three main hypotheses to explain the rise in food allergy: the dual-allergen exposure hypothesis, the hygiene hypothesis and the vitamin D hypothesis. In a recent systematic review of randomized controlled trials, only introduction of allergenic foods, namely egg and peanut, in the diet at the time of weaning and avoidance of temporary supplementation with cow's milk formula in the first few days of life showed low to moderate evidence of a preventive effect.

SUMMARY

For primary prevention, introduction of allergenic foods at the time of weaning and avoidance of temporary supplementation with cow's milk formula in the first few days of life has been recommended. Introduction of foods once allergy has been excluded may be beneficial for sensitized subjects (secondary prevention). Once food allergy has been established, it is important to minimise complications (tertiary prevention) through allergen avoidance, timely treatment of allergic reactions, control of atopic co-morbidities and dietetic and psychological support, as appropriate. Immunomodulatory treatments can potentially be disease-modifying and require further research.

Advances and novel developments in allergic rhinitis

Allergic rhinitis (AR) is an upper airway disease with high prevalence in the world, and therefore needs to be thoroughly investigated and treated accordingly. Although the mechanisms underlying the pathology and treatment of AR have been widely studied, many aspects of AR are still unclear and warrant further investigations. The purpose of the present review was therefore to report recently published papers, which highlight the novel mechanisms and treatments of AR. These include role of environment, important proteins and cells, and some other factors in the pathogenesis of AR; as well as the role of immunotherapy and biologics in the treatment of AR.

Null association between serum 25-hydroxyvitamin D levels with allergic rhinitis, allergic sensitization and non-allergic rhinitis: A Mendelian randomization study

BACKGROUND

Previous observational studies have not found a conclusive association between serum 25-hydroxyvitamin D (25(OH)D) levels and allergic rhinitis (AR) or allergic sensitization (AS).

OBJECTIVE

To investigate a causal association between 25(OH)D levels with risk of AR and AS, using a two-sample Mendelian randomization (MR) approach.

METHODS

Seven single nucleotide polymorphisms (SNPs), previously shown to be associated with serum 25(OH)D levels, were identified as instrumental variables. The primary outcome was AR, and the secondary outcomes were AS and non-allergic rhinitis (NAR). The genome-wide association (GWA) summary statistics of the outcomes were obtained from two cohort studies (EAGLE Consortium and UK Biobank). An MR analysis with random-effects inverse-variance weighted method was performed as the primary analysis to estimate overall effect size (odds ratio [OR] and 95% confidence interval [CI]). Sensitivity analysis using weighted median method and MR-Egger regression method was conducted. A subgroup analysis based on 25(OH)D synthesis-related SNPs was further applied.

RESULTS

Serum 25(OH)D levels were not causally associated with risk of AR (OR: 0.960; 95% CI: 0.779-1.184), AS (OR: 1.059; 95% CI: 0.686 to 1.634) or NAR (OR: 0.937; 95% CI: 0.588-1.491). Subgroup analysis also showed null association between 25(OH)D synthesis-related SNPs and the outcomes. Sensitivity analyses yielded similar results.

CONCLUSIONS AND CLINICAL RELEVANCE

This MR study found no evidence supporting a causal association between serum 25(OH)D levels and risk of AR, AS and NAR in European-ancestry population. This argues against the previous postulation that vitamin D supplementation is effective in prevention of allergic diseases.

Respiratory infections in allergic children: the preventive role of a multicomponent nutraceutical

Allergic children with respiratory infections (RI) are a demanding challenge for the paediatrician. Antibiotic prescription represents a critical problem, mainly concerning the growing issue of resistance. To prevent RI would be therefore a goal in clinical practice. In this regard, modulation of immune system may have a critical role. The aim of the present study was to measure the number of respiratory infections and the use of antibiotics in two groups of children suffering from allergic rhinoconjunctivitis. The first group took a course of a nutraceutical (Lertal®) before the observation (active group, AG); a second one was considered as control (control group, CG). The children were visited at baseline and after 1 year. The number of RI and of antibiotic courses was the primary outcomes. Children in AG reported a significant reduced number of RI and of antibiotic course in comparison with CG (p=0.01 and 0.002 respectively). In conclusion, the current study showed that a course with a multicomponent nutraceutical could reduce the number of respiratory infections and consequently the use of antibiotics in children with allergic rhinoconjunctivitis.

Epicutaneous sensitization in the development of food allergy: What is the evidence and how can this be prevented?

There is increasing evidence regarding the importance of allergic sensitization through the skin. In this review, we provide an overview of the atopic march and immune mechanism underlying the sensitization and effector phase of food allergy. We present experimental models and human data that support the concept of epicutaneous sensitization and how this forms one half of the dual-allergen exposure hypothesis. We discuss specific important elements in the skin (FLG and other skin barrier gene mutations, Langerhans cells, type 2 innate lymphoid cells, IL-33, TSLP) that have important roles in the development of allergic responses as well as the body of evidence on environmental allergen exposure and how this can sensitize an individual. Given the link between skin barrier impairment, atopic dermatitis, food allergy, allergic asthma, and allergic rhinitis, it is logical that restoring the skin barrier and prevention or treating atopic dermatitis would have beneficial effects on prevention of related allergic diseases, particularly food allergy. We present the experimental and human studies that have evaluated this approach and discuss various factors which may influence the success of these approaches, such as the type of emollient chosen for the intervention, the role of managing skin inflammation, and differences between primary and secondary prevention of atopic dermatitis to achieve the desired outcome.