Early life precursors, epigenetics, and the development of food allergy

The methylation profile of IL4, IL5, IL10, IFNG and FOXP3 associated with environmental exposures differed between Polish infants with the food allergy and/or atopic dermatitis and without the disease

Objectives

Epigenetic dynamics has been indicated to play a role in allergy development. The environmental stimuli have been shown to influence the methylation processes. This study investigated the differences in CpGs methylation rate of immune-attached genes between healthy and allergic infants. The research was aimed at finding evidence for the impact of environmental factors on methylation-based regulation of immunological processes in early childhood.

Methods

The analysis of methylation level of CpGs in the IL4, IL5, IL10, IFNG and FOXP3 genes was performed using high resolution melt real time PCR technology. DNA was isolated from whole blood of Polish healthy and allergic infants, with food allergy and/or atopic dermatitis, aged under six months.

Results

The significantly lower methylation level of FOXP3 among allergic infants compared to healthy ones was reported. Additional differences in methylation rates were found, when combining with environmental factors. In different studied groups, negative correlations between age and the IL10 and FOXP3 methylation were detected, and positive - in the case of IL4. Among infants with different allergy symptoms, the decrease in methylation level of IFNG, IL10, IL4 and FOXP3 associated with passive smoke exposure was observed. Complications during pregnancy were linked to different pattern of the IFNG, IL5, IL4 and IL10 methylation depending on allergy status. The IFNG and IL5 methylation rates were higher among exclusively breastfed infants with atopic dermatitis compared to the non-breastfed. A decrease in the IFNG methylation was noted among allergic patients fed exclusively with milk formula. In different study groups, a negative correlation between IFNG, IL5 methylation and maternal BMI or IL5 methylation and weight was noted. Some positive correlations between methylation rate of IL10 and child's weight were found. A higher methylation of IL4 was positively correlated with the number of family members with allergy.

Conclusion

The FOXP3 methylation in allergic infants was lower than in the healthy ones. The methylation profile of IL4, IL5, IL10, IFNG and FOXP3 associated with environmental exposures differed between the studied groups. The results offer insights into epigenetic regulation of immunological response in early childhood.

Trained innate immunity, epigenetics, and food allergy

In recent years the increased incidence of food allergy in Western culture has been associated with environmental factors and an inappropriate immune phenotype. While the adaptive immune changes in food allergy development and progression have been well-characterized, an increase in innate cell frequency and activation status has also recently received greater attention. Early in prenatal and neonatal development of human immunity there is a reliance on epigenetic and metabolic changes that stem from environmental factors, which are critical in training the immune outcomes. In the present review, we discuss how trained immunity is regulated by epigenetic, microbial and metabolic factors, and how these factors and their impact on innate immunity have been linked to the development of food allergy. We further summarize current efforts to use probiotics as a potential therapeutic approach to reverse the epigenetic and metabolic signatures and prevent the development of severe anaphylactic food allergy, as well as the potential use of trained immunity as a diagnostic and management strategy. Finally, trained immunity is presented as one of the mechanisms of action of allergen-specific immunotherapy to promote tolerogenic responses in allergic individuals.

Multi-Omic Profiles in Infants at Risk for Food Reactions

Food reactions (FR) are multifactorial and impacted by medical, demographic, environmental, and immunologic factors. We hypothesized that multi-omic analyses of host-microbial factors in saliva would enhance our understanding of FR development. This longitudinal cohort study included 164 infants followed from birth through two years. The infants were identified as FR (n = 34) or non-FR (n = 130) using the Infant Feeding Practice II survey and medical record confirmation. Saliva was collected at six months for the multi-omic assessment of cytokines, mRNAs, microRNAs, and the microbiome/virome. The levels of one miRNA (miR-203b-3p, adj. p = 0.043, V = 2913) and one viral phage (Proteus virus PM135, adj. p = 0.027, V = 2955) were lower among infants that developed FRs. The levels of one bacterial phylum (Cyanobacteria, adj. p = 0.048, V = 1515) were higher among infants that developed FR. Logistical regression models revealed that the addition of multi-omic features (miR-203b-3p, Cyanobacteria, and Proteus virus PM135) improved predictiveness for future FRs in infants (p = 0.005, X2 = 12.9), predicting FRs with 72% accuracy (AUC = 0.81, sensitivity = 72%, specificity = 72%). The multi-omic analysis of saliva may enhance the accurate identification of infants at risk of FRs and provide insights into the host/microbiome interactions that predispose certain infants to FRs.

Epigenetic/genetic variations in CG-rich elements of immune-related genes contribute to food allergy development during childhood

BACKGROUND

Genetic areas of FOXP3 TSDR, human leukocyte antigen-G (HLA-G) upstream of CpG island 96, CpG41 and CpG73 islands of the HLA-DRB1 and HLA-DQB1 genes respectively, previously documented to display immune-modulatory properties, were subjected to epigenetic/genetic analysis to assess their influence in IgE-mediated food allergy (FA) development in children.

METHODS

Sixty-four orally challenged and IgE-tested food allergic subjects together with 44 controls were recruited. Targeted pyrosequencing analysis to detect DNA methylation status and genetic variations was utilized and experimental results obtained were analyzed by a statistical software platform and correlated to clinical data. Also, transcription factor (TF) binding sites in study areas were unmasked by the JASPAR prediction database.

RESULTS

Parents' smoking was significantly correlated with aberrant methylation patterns, regardless of food allergic or control status. HLA-G promoter region showed a trend for hypomethylation in food allergic subjects, with one of the CG sites displaying significantly decreased methylation values. Rs1233333, residing within the HLA-G promoter region preserved a protective role toward DNA methylation. Variable methylation patterns were recorded for CpG41 of the HLA-DRB1 gene and hypermethylation of the region was significantly correlated with the presence of single nucleotide polymorphisms (SNPs). TFs' recognition sites, located in studied genetic areas and exerting pivotal regulatory biological roles, are potentially affected by divergent DNA methylation status.

CONCLUSIONS

We propose that HLA-G expression is triggered by food-derived allergens, providing a Treg^{FoxP3-/HLA-G+} subpopulation generation to promote direct immune tolerance. Furthermore, clear evidence is provided for the underlying co-operation of genetic polymorphisms with epigenetic events, mainly at the CpG41 island of the HLA-DRB1 gene, which needs an extended investigation and elucidation.

Nutrition during Pregnancy and Lactation: Epigenetic Effects on Infants’ Immune System in Food Allergy

Food allergies are an increasing health problem worldwide. They are multifactorial diseases, in which the genome alone does not explain the development of the disease, but a genetic predisposition and various environmental factors contribute to their onset. Environmental factors, in particular nutritional factors, in the early stages of life are recognized as key elements in the etiology of food allergies. There is growing evidence advising that nutrition can affect the risk of developing food allergies through epigenetic mechanisms elicited by the nutritional factors themselves or by modulating the gut microbiota and its functional products. Gut microbiota and postbiotics can in turn influence the risk of food allergy development through epigenetic mechanisms. Epigenetic programming accounts not only for the short-term effects on the individual’s health status, but also for those observed in adulthood. The first thousand days of life represent an important window of susceptibility in which environmental factors, including nutritional ones, can influence the risk of developing allergies through epigenetic mechanisms. From this point of view, it represents an interesting window of opportunity and intervention. This review reports the main nutritional factors that in the early stages of life can influence immune oral tolerance through the modulation of epigenetic mechanisms.

Epigenetics in Food Allergy and Immunomodulation

Food allergy (FA) is an increasing problem worldwide and, over recent years, its prevalence is rising in developed countries. Nowadays, the immunological and cellular processes that occur in the allergic reactions are not fully understood, which hampers the development of in vitro diagnostic tools and further treatment options. Moreover, allergic diseases could be reinforced by environmental exposure and genetic modifications. Gene expression can be controlled by different epigenetic mechanisms like DNA methylation, histone modifications, and microRNAs. In addition, several environmental factors such as dietary components (vitamin D, butyrate, folic acid) are able to regulate this epigenetic mechanism. All these factors produce modifications in immune genes that could alter the development and function of immune cells, and therefore the etiology of the disease. Furthermore, these epigenetic mechanisms have also an influence on immunomodulation, which could explain sustained responsiveness or unresponsiveness during immunotherapy due to epigenetic modifications in key genes that induce tolerance in several FA. Thus, in this review we focus on the different epigenetic mechanisms that occur in FA and on the influence of several dietary components in these gene modifications.

Raw Milk-Induced Protection against Food Allergic Symptoms in Mice Is Accompanied by Shifts in Microbial Community Structure

The mechanism underlying the allergy-protective effects of raw cow’s milk is still unknown, but the modulation of the gut microbiome may play a role. The effects of consuming raw cow’s milk or processed milk on fecal microbial communities were therefore characterized in an experimental murine model. C3H/HeOuJ mice were treated with raw milk, pasteurized milk, skimmed raw milk, pasteurized milk supplemented with alkaline phosphatase (ALP), or phosphate-buffered saline (PBS) for eight days prior to sensitization and challenge with ovalbumin (OVA). Fecal samples were collected after milk exposure and after OVA sensitization, and microbiomes were characterized using 16S ribosomal RNA gene amplicon sequencing. Treatment with raw milk prior to OVA sensitization increased the relative abundance of putative butyrate-producing bacteria from the taxa Lachnospiraceae UCG-001, Lachnospiraceae UCG-008, and Ruminiclostridium 5 (Clostridial clusters XIVa and IV), while it decreased the relative abundance of Proteobacterial genera such as Parasutterella, a putative pro-inflammatory bacterial genus. This effect was observed after eight days of raw milk exposure and became more pronounced five weeks later, after allergic sensitization in the absence of milk. Similar trends were observed after treatment with skimmed raw milk. Conversely, the feeding of pasteurized milk led to a loss of allergy protection and a putative dysbiotic microbiome. The addition of ALP to pasteurized milk restored the protective effect observed with raw milk and mitigated some of the microbial community alterations associated with milk pasteurization. Raw milk-induced protection against food allergic symptoms in mice is accompanied by an increased relative abundance of putative butyrate-producing Clostridiales and a decreased relative abundance of putative pro-inflammatory Proteobacteria. Given the safety concerns regarding raw milk consumption, this knowledge is key for the development of new, microbiologically safe, preventive strategies to reduce the incidence of allergic diseases.

Targeted DNA methylation profiling reveals epigenetic signatures in peanut allergy

DNA methylation (DNAm) has been shown to play a role in mediating food allergy; however, the mechanism by which it does so is poorly understood. In this study, we used targeted next-generation bisulfite sequencing to evaluate DNAm levels in 125 targeted highly informative genomic regions containing 602 CpG sites on 70 immune-related genes to understand whether DNAm can differentiate peanut allergy (PA) versus nonallergy (NA). We found PA-associated DNAm signatures associated with 12 genes (7 potentially novel to food allergy, 3 associated with Th1/Th2, and 2 associated with innate immunity), as well as DNAm signature combinations with superior diagnostic potential compared with serum peanut–specific IgE for PA versus NA. Furthermore, we found that, following peanut protein stimulation, peripheral blood mononuclear cell (PBMCs) from PA participants showed increased production of cognate cytokines compared with NA participants. The varying responses between PA and NA participants may be associated with the interaction between the modification of DNAm and the interference of environment. Using Euclidean distance analysis, we found that the distances of methylation profile comprising 12 DNAm signatures between PA and NA pairs in monozygotic (MZ) twins were smaller than those in randomly paired genetically unrelated individuals, suggesting that PA-related DNAm signatures may be associated with genetic factors.

Interleukin 10: the critical role of a pleiotropic cytokine in food allergy

Despite advances in research, the pathophysiology of food allergy has not yet been fully elucidated. IL-10 has both a pro- and anti-inflammatory effect on the development of food allergy and in order to understand its different immune-modulatory effects the factors that influence the inflammatory microenvironment need to be taken into account. Specific single nucleotide polymorphisms of the IL-10 gene seem to confer an increased risk of developing food allergy, but to date there is a substantial lack of genome- wide association studies regarding the genetic and epigenetic underpinnings of the disease. Special interest has been drawn to the development of allergen-specific regulatory CD4+CD25+ T-cells secreting IL-10 in the immunotherapy of allergic diseases. In addition, a distinct population of human tolerogenic dendritic cells (DC), DC-10 seems to hold great potential and could potentially serve as a therapeutic tool to improve the management of food allergy.

Identification of Novel Biomarkers for Drug Hypersensitivity After Sequencing of the Promoter Area in 16 Genes of the Vitamin D Pathway and the High-Affinity IgE Receptor

The prevalence of allergic diseases and drug hypersensitivity reactions (DHRs) during recent years is increasing. Both, allergic diseases and DHRs seem to be related to an interplay between environmental factors and genetic susceptibility. In recent years, a large effort in the elucidation of the genetic mechanisms involved in these disorders has been made, mostly based on case-control studies, and typically focusing on isolated SNPs. These studies provide a limited amount of information, which now can be greatly expanded by the complete coverage that Next Generation Sequencing techniques offer. In this study, we analyzed the promoters of sixteen genes related to the Vitamin D pathway and the high-affinity IgE receptor, including FCER1A, MS4A2, FCER1G, VDR, GC, CYP2R1, CYP27A1, CYP27B1, CYP24A1, RXRA, RXRB, RXRG, IL4, IL4R, IL13, and IL13RA1. The study group was composed of patients with allergic rhinitis plus asthma (AR+A), patients with hypersensitivity to beta-lactams (BLs), to NSAIDs including selective hypersensitivity (SH) and cross-reactivity (CR), and healthy controls without antecedents of atopy or adverse drug reactions. We identified 148 gene variations, 43 of which were novel. Multinomial analyses revealed that three SNPs corresponding to the genes FCER1G (rs36233990 and rs2070901), and GC (rs3733359), displayed significant associations and, therefore, were selected for a combined dataset study in a cohort of 2,476 individuals. The strongest association was found with the promoter FCER1G rs36233990 SNP that alters a transcription factor binding site. This SNP was over-represented among AR+A patients and among patients with IgE-mediated diseases, as compared with control individuals or with the rest of patients in this study. Classification models based on the above-mentioned SNPs were able to predict correct clinical group allocations in patients with DHRs, and patients with IgE-mediated DHRs. Our findings reveal gene promoter SNPs that are significant predictors of drug hypersensitivity, thus reinforcing the hypothesis of a genetic predisposition for these diseases.

A curated collection of transcriptome datasets to investigate the molecular mechanisms of immunoglobulin E-mediated atopic diseases

Prevalence of allergies has reached ~20% of population in developed countries and sensitization rate to one or more allergens among school age children are approaching 50%. However, the combination of the complexity of atopic allergy susceptibility/development and environmental factors has made identification of gene biomarkers challenging. The amount of publicly accessible transcriptomic data presents an unprecedented opportunity for mechanistic discoveries and validation of complex disease signatures across studies. However, this necessitates structured methodologies and visual tools for the interpretation of results. Here, we present a curated collection of transcriptomic datasets relevant to immunoglobin E-mediated atopic diseases (ranging from allergies to primary immunodeficiencies). Thirty-three datasets from the Gene Expression Omnibus, encompassing 1860 transcriptome profiles, were made available on the Gene Expression Browser (GXB), an online and open-source web application that allows for the query, visualization and annotation of metadata. The thematic compositions, disease categories, sample number and platforms of the collection are described. Ranked gene lists and sample grouping are used to facilitate data visualization/interpretation and are available online via GXB (http://ige.gxbsidra.org/dm3/geneBrowser/list). Dataset validation using associated publications showed good concordance in GXB gene expression trend and fold-change.

Solid Food Introduction and the Development of Food Allergies

The rise of food allergy in childhood, particularly among developed countries, has a significant weight on public health and involves serious implications for patients' quality of life. Even if the mechanisms of food tolerance and the complex interactions between the immune system and environmental factors are still mainly unknown, pediatricians have worldwide implemented preventive measures against allergic diseases. In the last few decades, the prevention of food allergy has tracked various strategies of complementary feeding with a modification of international guidelines from delayed introduction to early weaning. Current evidence shows that complementary foods, including allergenic ones, should be introduced into diet after four months, or even better, following World Health Organization advice, around six months irrespective of risk for allergy of the individual. The introduction of peanut is recommended before 12 months of age among infants affected by severe eczema and/or egg allergy to diminish the occurrence of peanut allergy in countries with high peanut consumption. The introduction of heated egg at 6⁻8 months of age may reduce egg allergy. Infants at high risk of allergy similarly to healthy children should introduce complementary foods taking into account family and cultural preferences.

Early Infant Feeding Practices as Possible Risk Factors for Immunoglobulin E-Mediated Food Allergies in Kuwait

Objective

Early feeding and infant exposures have been suggested as potential risk factors for immunoglobulin E- (IgE-) mediated food allergy (FA). We aimed to evaluate the association between IgE-mediated FA in children and early exposures including the child's nutritional status, breastfeeding and its duration, the age at which the solid food was first introduced, antibiotic exposure during the first year of life, and the child's vitamin D status during infancy.

Design

A case-control study.

Setting and Subjects

Children aged 0–13 years were recruited from pediatric allergy and immunology clinics (PAICs) located at major government hospitals in Kuwait (total FA cases: n = 100; boys = 67%), and healthy controls (n = 100, boys 55%) were recruited from various vaccination units at primary healthcare centers.

Results

Cow's milk allergy was the most common type of FA. FA status was independently associated with the early exposures of exclusive breastfeeding (aOR = 15.55 (3.26–74.19), p = 0.001), vitamin D deficiency or insufficiency during infancy (aOR = 5.42 (1.92–15.30), p = 0.001), and antibiotic exposure during the first year of life (aOR = 5.00 (1.58–15.84), p = 0.006).

Conclusions

FA is highly prevalent among children in Kuwait, and our data indicate that early nutrition-related and antibiotic exposures are associated with FA risk.

Forkhead box protein 3 demethylation is associated with tolerance induction in peanut-induced intestinal allergy

BACKGROUND

Regulatory T (Treg) cells play an essential role in the maintenance of immune homeostasis in allergic diseases.

OBJECTIVES

We sought to define the mechanisms underlying induction of tolerance to peanut protein and prevention of the development of peanut allergy.

METHODS

High or low doses of peanut extract were administered to pups every day for 2 weeks before peanut sensitization and challenge. After challenge, symptoms, Treg cell numbers, and forkhead box protein 3 (Foxp3), TH2 and TH17 cytokine, and Tgfβ expression in mesenteric lymph node (MLN) CD4+ T cells and jejunum were monitored. Treg cell suppressive activity and Foxp3 methylation in MLN CD4+ T cells were assayed.

RESULTS

Feeding high but not low doses of peanut before sensitization induced tolerance, as demonstrated by prevention of diarrhea and peanut-specific IgE responses, increases in the percentage of CD4+CD25+FoxP3+ cells in MLNs, and Foxp3 mRNA and protein expression in CD4+ cells from MLNs or jejunum. Feeding high doses of peanut before sensitization decreased percentages of CD3+CD4+IL-13+ and CD3+CD4+IL-17+ cells in MLNs and decreased Il13 and Il17a and increased Tgfβ mRNA expression in the jejunum; numbers of CD103+ dendritic cells in MLNs were significantly increased. Treg cell suppression was shown to be antigen specific. Foxp3 methylation was increased in peanut extract-sensitized and challenged mice, whereas in tolerized mice levels were significantly reduced.

CONCLUSIONS

Feeding high doses of peanut to pups induced tolerance to peanut protein. Foxp3 demethylation was associated with tolerance induction, indicating that Treg cells play an important role in the regulation of peanut sensitivity and maintenance of immune homeostasis.

Epigenetic Changes During Food-Specific Immunotherapy

PURPOSE OF REVIEW

The prevalence and severity of IgE-mediated food allergy has increased dramatically over the last 15 years and is becoming a global health problem. Multiple lines of evidence suggest that epigenetic modifications of the genome resulting from gene-environment interactions have a key role in the increased prevalence of atopic disease. In this review, we describe the recent evidence suggesting how epigenetic changes mediate susceptibility to food allergies, and discuss how immunotherapy (IT) may reverse these effects. We discuss the areas of the epigenome as yet unexplored in terms of food allergy and IT such as histone modification and chromatin accessibility, and new techniques that may be utilized in future studies.

RECENT FINDINGS

Recent findings provide strong evidence that DNA methylation of certain promoter regions such as Forkhead box protein 3 is associated with clinical reactivity, and further, can be changed during IT treatment. Reports on other epigenetic changes are limited but also show evidence of significant change based on both disease status and treatment. In comparison to epigenetic studies focusing on asthma and allergic rhinitis, food allergy remains understudied. However, within the next decade, it is likely that epigenetic modifications may be used as biomarkers to aid in diagnosis and treatment of food-allergic patients. DNA methylation at specific loci has shown associations between food challenge outcomes, successful desensitization treatment, and overall phenotype compared to healthy controls.

Are genetic tests informative in predicting food allergy?

PURPOSE OF REVIEW

Food allergy is common among children and adults worldwide. Recent studies have improved our understanding of the genetic mechanism of food allergy and further studies may result in clinical application through genetic testing.

RECENT FINDINGS

Genetic factors are important in the development of food allergy. An increasing number of genes have been associated with food allergy in recent years. These include mutations and genetic variants in the filaggrin gene, the association of human leukocyte antigen DR and DQ regions with food allergy, copy number variation impacting CTNNA3 and RBFOX1, DNA methylation that partially mediates single nucleotide polymorphism association at the HLA-DR and DQ loci, as well as other genes. Several studies have implicated differences in gut microbiota composition in food allergy.

SUMMARY

With the advance of high-throughput genotyping and sequencing techniques together with improved analytical methods, the contributions of genetic and environmental factors in development of food allergy are being clarified. Yet much remains to be explored and more studies with larger sample sizes, better phenotyping, and improved quality control genomics methods are needed. The ultimate goal is the development of a panel of reliable markers for genetic testing in food allergy to improve overall patient care.

Environmental Justice and Underserved Communities

Underserved communities suffer from environmental inequities. Gases lead to hypoxia and respiratory compromise, ozone to increased respiratory illnesses and decreased mental acuity, and mercury to prenatal cognitive disabilities and antisocial behaviors. Lead toxicity is associated with developmental delays. Cadmium is linked with cancer. The smaller sizes of air pollution particulate matter are pathogenic and are associated with cardiovascular and pulmonary disease and nervous system disorders. Bisphenol A is being studied for possible links to cancer and pregnancy risks. Physicians should be aware of these dangers, especially in underserved communities and populations. Investigating possible environmental risks and education are key.

Regulatory T cells in allergic diseases

The pathogenesis of allergic diseases entails an ineffective tolerogenic immune response to allergens. Regulatory T (Treg) cells play a key role in sustaining immune tolerance to allergens, yet mechanisms by which Treg cells fail to maintain tolerance in patients with allergic diseases are not well understood. We review current concepts and established mechanisms regarding how Treg cells regulate different components of allergen-triggered immune responses to promote and maintain tolerance. We will also discuss more recent advances that emphasize the "dual" functionality of Treg cells in patients with allergic diseases: how Treg cells are essential in promoting tolerance to allergens but also how a proallergic inflammatory environment can skew Treg cells toward a pathogenic phenotype that aggravates and perpetuates disease. These advances highlight opportunities for novel therapeutic strategies that aim to re-establish tolerance in patients with chronic allergic diseases by promoting Treg cell stability and function.

Resolving the etiology of atopic disorders by using genetic analysis of racial ancestry

Atopic dermatitis (AD), food allergy, allergic rhinitis, and asthma are common atopic disorders of complex etiology. The frequently observed atopic march from early AD to asthma, allergic rhinitis, or both later in life and the extensive comorbidity of atopic disorders suggest common causal mechanisms in addition to distinct ones. Indeed, both disease-specific and shared genomic regions exist for atopic disorders. Their prevalence also varies among races; for example, AD and asthma have a higher prevalence in African Americans when compared with European Americans. Whether this disparity stems from true genetic or race-specific environmental risk factors or both is unknown. Thus far, the majority of the genetic studies on atopic diseases have used populations of European ancestry, limiting their generalizability. Large-cohort initiatives and new analytic methods, such as admixture mapping, are currently being used to address this knowledge gap. Here we discuss the unique and shared genetic risk factors for atopic disorders in the context of ancestry variations and the promise of high-throughput "-omics"-based systems biology approach in providing greater insight to deconstruct their genetic and nongenetic etiologies. Future research will also focus on deep phenotyping and genotyping of diverse racial ancestry, gene-environment, and gene-gene interactions.

Transgenerational transmission of pregestational and prenatal experience: maternal adversity, enrichment, and underlying epigenetic and environmental mechanisms

Transgenerational transmission refers to positive and negative adaptations in brain function and behavior that affect following generations. In this paper, empirical findings regarding the transgenerational transmission of maternal adversity during three critical periods - childhood, pregestational adulthood and pregnancy - will be reviewed in terms of pregnancy outcomes, maternal care, offspring behavior and development, and physiological functioning. Research on the transgenerational transmission of enrichment and the implications for interventions to ameliorate the consequences of adversity will also be presented. In the final section, underlying epigenetic and environmental mechanisms that have been proposed to explain how experience is transferred across generations through transgenerational transmission will be reviewed. Directions for future research are suggested throughout.

Cow's milk allergy in Dutch children: an epigenetic pilot survey

Background

Cow’s milk allergy (CMA) is a common disease in infancy. Early environmental factors are likely to contribute to CMA. It is known that epigenetic gene regulation can be altered by environmental factors. We have set up a proof of concept study, aiming to detect epigenetic associations specific with CMA.

Methods

We studied children from the Dutch EuroPrevall birth cohort study (N = 20 CMA, N = 23 controls, N = 10 tolerant boys), age and gender matched. CMA was challenge proven. Bisulfite converted DNA (blood) was analyzed using the 450K infinium DNA-methylation array. Four groups (combined, girls, boys and tolerant boys) were analysed between CMA and controls. Statistical analysis and pathway-analysis were performed in “R” using IMA, Minfi and the global-test package. Differentially methylated regions in DHX58, ZNF281, EIF42A and HTRA2 genes were validated by quantitative amplicon sequencing (ROCHE 454^®).

Results

General hypermethylation was found in the CMA group compared to control children, while this effect was absent in the tolerant group. Methylation differences were, among others, found in regions of DHX58, ZNF281, EIF42A and HTRA2 genes. Several of these genes are known to be involved in immunological pathways and associated with other allergies.

Conclusion

We show that epigenetic associations are involved in CMA. Although, the statistical power of our study is limited and our sample was based on whole blood, we were still able to detect feasible loci and pathways. Therefore our findings might contribute to future diagnostic or therapeutic interventions for specific CMA. Further studies have to confirm the findings of our study.

Electronic supplementary material

The online version of this article (doi:10.1186/s13601-016-0105-z) contains supplementary material, which is available to authorized users.

Aberrant 5'-CpG Methylation of Cord Blood TNFα Associated with Maternal Exposure to Polybrominated Diphenyl Ethers

Growing evidence suggests that maternal exposures to endocrine disrupting chemicals during pregnancy may lead to poor pregnancy outcomes and increased fetal susceptibility to adult diseases. Polybrominated diphenyl ethers (PBDEs), which are ubiquitously used flame-retardants, could leach into the environment; and become persistent organic pollutants via bioaccumulation. In the United States, blood PBDE levels in adults range from 30–100 ng/g- lipid but the alarming health concern revolves around children who have reported blood PBDE levels 3 to 9-fold higher than adults. PBDEs disrupt endocrine, immune, reproductive and nervous systems. However, the mechanism underlying its adverse health effect is not fully understood. Epigenetics is a possible biological mechanism underlying maternal exposure-child health outcomes by regulating gene expression without changes in the DNA sequence. We sought to examine the relationship between maternal exposure to environmental PBDEs and promoter methylation of a proinflammatory gene, tumor necrosis factor alpha (TNFα). We measured the maternal blood PBDE levels and cord blood TNFα promoter methylation levels on 46 paired samples of maternal and cord blood from the Boston Birth Cohort (BBC). We showed that decreased cord blood TNFα methylation associated with high maternal PBDE47 exposure. CpG site-specific methylation showed significantly hypomethylation in the girl whose mother has a high blood PBDE47 level. Consistently, decreased TNFα methylation associated with an increase in TNFα protein level in cord blood. In conclusion, our finding provided evidence that in utero exposure to PBDEs may epigenetically reprogram the offspring’s immunological response through promoter methylation of a proinflammatory gene.

Which infants with eczema are at risk of food allergy? Results from a population-based cohort

BACKGROUND

The relationship between early onset eczema and food allergy among infants has never been examined in a population-based sample using the gold standard for diagnosis, oral food challenge.

OBJECTIVE

We characterised the risk of challenge-proven food allergy among infants with eczema in the general population.

METHODS

One-year-old infants (n = 4453 meeting criteria for this analysis) were assessed for history of eczema, received a nurse-administered eczema examination and underwent skin prick testing to peanut, egg and sesame. Those with a detectable wheal to one of the test foods underwent an oral food challenge irrespective of wheal size. The risk of food allergy, stratified by eczema severity and age of onset, was estimated using multivariate logistic regression with population sampling weights.

RESULTS

One in five infants with eczema were allergic to peanut, egg white or sesame, compared to one in twenty-five infants without eczema (OR 6.2, 95% CI 4.9, 7.9, P < 0.001). The prevalence of peanut allergy was low in the absence of eczema (0.7% 95% CI 0.4, 1.1). Infants with eczema were 11.0 times more likely to develop peanut allergy (95% CI 6.6, 18.6) and 5.8 times more likely to develop egg allergy (95% CI 4.6, 7.4) by 12 months than infants without eczema. 50.8% of infants (95% CI 42.8, 58.9) with early eczema onset (<3 months) who required doctor-prescribed topical corticosteroid treatment developed challenge-proven food allergy.

CONCLUSION AND CLINICAL RELEVANCE

Eczema, across the clinical severity spectrum in infancy, is a strong risk factor for IgE-mediated food allergy. Infants with eczema were six times more likely to have egg allergy and 11 times more likely to have peanut allergy by 12 months than infants without eczema. Our data suggest that a heightened awareness of food allergy risk among healthcare practitioners treating infants with eczema, especially if early onset and severe, is warranted.

The role of epigenetic mediation and the future of food allergy research

IgE-mediated food allergy is a developing global health problem with prevalence rising at alarmingly fast rates. In this review, we discuss the interplay between genetics, epigenetics, and environmental exposures in the pathogenesis of food allergies. We aim to highlight the most recent evidence that suggests how epigenetic control may mediate genetic susceptibility of food allergies. We also examine how epigenetic modifications may be the key in explaining how environmental factors modulate and modify gene expression, leading to the dysregulation of immune tolerance and consequently, the development of food allergies. The emerging epigenetic paradigm in food allergies is likely to provide new mechanistic insight into food allergy risk and development as well as shape our therapeutic and preventive strategies.

Genome-wide association study identifies peanut allergy-specific loci and evidence of epigenetic mediation in US children

Food allergy (FA) affects 2–10% of U.S. children and is a growing clinical and public health problem. Here we conduct the first genome-wide association study of well-defined FA, including specific subtypes (peanut, milk, and egg) in 2,759 U.S. participants (1,315 children; 1,444 parents) from the Chicago Food Allergy Study; and identify peanut allergy (PA)-specific loci in the HLA-DR and -DQ gene region at 6p21.32, tagged by rs7192 (p=5.5×10⁻⁸) and rs9275596 (p=6.8×10⁻¹⁰), in 2,197 participants of European ancestry. We replicate these associations in an independent sample of European ancestry. These associations are further supported by meta-analyses across the discovery and replication samples. Both single-nucleotide polymorphisms (SNPs) are associated with differential DNA methylation levels at multiple CpG sites (p<5×10⁻⁸); and differential DNA methylation of the HLA-DQB1 and HLA-DRB1 genes partially mediate the identified SNP-PA associations. This study suggests that the HLA-DR and -DQ gene region likely poses significant genetic risk for PA.

Epigenetics and development of food allergy (FA) in early childhood

This review aims to highlight the latest advance on epigenetics in the development of food allergy (FA) and to offer future perspectives. FA, a condition caused by an immunoglobulin (Ig) E-mediated hypersensitivity reaction to food, has emerged as a major clinical and public health problem worldwide in light of its increasing prevalence, potential fatality, and significant medical and economic impact. Current evidence supports that epigenetic mechanisms are involved in immune regulation and that the epigenome may represent a key "missing piece" of the etiological puzzle for FA. There are a growing number of population-based epigenetic studies on allergy-related phenotypes, mostly focused on DNA methylation. Previous studies mostly applied candidate-gene approaches and have demonstrated that epigenetic marks are associated with multiple allergic diseases and/or with early-life exposures relevant to allergy development (such as early-life smoking exposure, air pollution, farming environment, and dietary fat). Rapid technological advancements have made unbiased genome-wide DNA methylation studies highly feasible, although there are substantial challenge in study design, data analyses, and interpretation of findings. In conclusion, epigenetics represents both an important knowledge gap and a promising research area for FA. Due to the early onset of FA, epigenetic studies of FA in prospective birth cohorts have the potential to better understand gene-environment interactions and underlying biological mechanisms in FA during critical developmental windows (preconception, in utero, and early childhood) and may lead to new paradigms in the diagnosis, prevention, and management of FA and provide novel targets for future drug discovery and therapies for FA.

Angiotensin converting enzyme inhibitor-related angioedema: onset, presentation, and management

OBJECTIVE

This study aimed to determine the duration of use, presentation, and management of angiotensin converting enzyme (ACE) inhibitor-related angioedema patients at an urban academic medical center.

METHODS

Retrospective chart review.

RESULTS

Eighty-eight patients who presented with ACE inhibitor-related angioedema between January 1, 2012, and December 31, 2012, were identified. They presented anywhere from 1 day to 20 years after starting an ACE inhibitor. About half the patients (50.7%) presented after taking an ACE inhibitor for at least 1 year. Fifty-five patients were female (62.5%). Twenty-eight patients (31.8%) had an airway intervention with 27 intubated and 1 requiring cricothyroidotomy. Six patients were intubated after more than 1 flexible laryngoscopy. The percentage of patients with involvement of the face, lips, tongue, floor of mouth, soft palate/uvula, and larynx were 12.5%, 60.2%, 39.7%, 6.8%, 17.0%, and 29.5%, respectively. Sixty-eight percent of patients with laryngeal edema were intubated. The majority of patients were treated with a corticosteroid and H1 and H2 receptor antagonists.

CONCLUSION

Angioedema can occur at any time after starting ACE inhibitor use, with nearly half occurring after 1 year of use. Laryngeal involvement occurred in a minority of patients, but most of these patients were felt to require airway protection.

Nutritional challenges for children in societies in transition

PURPOSE OF REVIEW

This review is to explore the childhood nutrition and health in relation to socioeconomic changes in transitional countries, and to describe the good experiences and policies in these countries to combat childhood nutritional challenges.

RECENT FINDINGS

Double burden of malnutrition - the coexistence of under-nutrition and over-nutrition in the same population - is a prominent public health concern in transitional countries. With rapid industrialization, these countries are facing a growing epidemic of overweight/obesity in children and adolescents. The increasing prevalence of childhood overweight/obesity is a likely consequence of behavioral changes, and accompanied with an increasing incidence of noncommunicable chronic diseases. Although remarkable improvement of childhood nutrition was achieved, the stunting growth and micronutrient deficiency remain to be child health issues in transitional countries.

SUMMARY

The social transition caused a broad range of nutrition-associated problems. Previous successful experiences indicated that if appropriate action is undertaken, the child nutritional problems accompanied with economic transition could be controlled to some extent. However, greater efforts are needed to improve the status of childhood nutrition in transitional countries.

Food allergy diagnosis and therapy: where are we now?

Food allergy is a growing worldwide epidemic that adversely effects up to 10% of the population. Causes and risk factors remain unclear and diagnostic methods are imprecise. There is currently no accepted treatment for food allergy. Therefore, there is an imminent need for greater understanding of food allergies, revised diagnostics and development of safe, effective therapies. Oral immunotherapy provides a particularly promising avenue, but is still highly experimental and not ready for clinical use.

Epigenetics of allergy

Epigenetics has recently been considered as a potential mechanism involved in the development of many disorders, including allergic diseases. Animal models have shown that environmental factors such as maternal tobacco smoke or mechanical ventilation can alter gene transcription and consequently the structure and function of lungs. Moreover, asthma and other allergic diseases (atopic dermatitis and food allergy) are influenced by epigenetics. In fact, the exposure to environmental factors during early childhood may induce a long-lasting altered genetic state adapting to a persistent "Th2 state" thus influencing the development of asthma or atopic dermatitis and food allergy if alterations involve the filaggrin gene. In conclusion, progresses have been made linking environmental pollution, environmental tobacco smoke (ETS) and diet exposure with atopy through epigenetic mechanisms. Furthermore, considerable advances have been made implicating epigenetic mechanisms in T cell differentiation. However, much more research is still needed, in particular to define the clinical consequences of such epigenetic alterations.

Food allergy in Asia: how does it compare?

Asia is a populous and diverse region and potentially an important source of information on food allergy. This review aims to summarize the current literature on food allergy from this region, comparing it with western populations. A PubMed search using strategies "Food allergy AND Asia", "Food anaphylaxis AND Asia", and "Food allergy AND each Asian country" was made. Overall, 53 articles, published between 2005 and 2012, mainly written in English were reviewed. The overall prevalence of food allergy in Asia is somewhat comparable to the West. However, the types of food allergy differ in order of relevance. Shellfish is the most common food allergen from Asia, in part due to the abundance of seafood in this region. It is unique as symptoms vary widely from oral symptoms to anaphylaxis for the same individual. Data suggest that house dust mite tropomysin may be a primary sensitizer. In contrast, peanut prevalence in Asia is extremely low compared to the West for reasons not yet understood. Among young children and infants, egg and cow's milk allergy are the two most common food allergies, with prevalence data comparable to western populations. Differences also exist within Asia. Wheat allergy, though uncommon in most Asian countries, is the most common cause of anaphylaxis in Japan and Korea, and is increasing in Thailand. Current food allergy data from Asia highlights important differences between East and West, and within the Asian region. Further work is needed to provide insight on the environmental risk factors accounting for these differences.

Novel insights into mechanisms of food allergy and allergic airway inflammation using experimental mouse models

Over the last decades, considerable efforts have been undertaken in the development of animal models mimicking the pathogenesis of allergic diseases occurring in humans. The mouse has rapidly emerged as the animal model of choice, due to considerations of handling and costs and, importantly, due to the availability of a large and increasing arsenal of genetically modified mouse strains and molecular tools facilitating the analysis of complex disease models. Here, we review latest developments in allergy research that have arisen from in vivo experimentation in the mouse, with a focus on models of food allergy and allergic asthma, which constitute major health problems with increasing incidence in industrialized countries. We highlight recent novel findings and controversies in the field, most of which were obtained through the use of gene-deficient or germ-free mice, and discuss new potential therapeutic approaches that have emerged from animal studies and that aim at attenuating allergic reactions in human patients.