Genetic variation at the Th2 immune gene IL13 is associated with IgE-mediated paediatric food allergy

Early-life risk factors which govern pro-allergic immunity

Allergic diseases affect up to 40% of the global population with a substantial rise in food allergies, in particular, over the past decades. For the majority of individuals with allergy fundamental programming of a pro-allergic immune system largely occurs in early childhood where it is crucially governed by prenatal genetic and environmental factors, including their interactions. These factors include several genetic aberrations, such as filaggrin loss-of-function mutations, early exposure to respiratory syncytial virus, and various chemicals such as plasticizers, as well as the influence of the gut microbiome and numerous lifestyle circumstances. The effects of such a wide range of factors on allergic responses to an array of potential allergens is complex and the severity of these responses in a clinical setting are subsequently not easy to predict at the present time. However, some parameters which condition a pro-allergic immune response, including severe anaphylaxis, are becoming clearer. This review summarises what we currently know, and don't know, about the factors which influence developing pro-allergic immunity particularly during the early-life perinatal period.

Genetic relationship between the immune system and autism

Autism spectrum disorder (ASD) is a common and complex neurodevelopmental condition. The pathophysiology of ASD is poorly defined; however, it includes a strong genetic component and there is increasing evidence to support a role of immune dysregulation. Nonetheless, it is unclear which immune phenotypes link to ASD through genetics. Hence, we investigated the genetic correlation between ASD and diverse classes of immune conditions and markers; and if these immune-related genetic factors link to specific autistic-like traits in the population. We estimated global and local genetic correlations between ASD (n = 55,420) and 11 immune phenotypes (n = 14,256-755,406) using genome-wide association study summary statistics. Subsequently, polygenic scores (PGS) for these immune phenotypes were calculated in a population-based sample (n = 2487) and associated to five autistic-like traits (i.e., attention to detail, childhood behaviour, imagination, rigidity, social skills), and a total autistic-like traits score. Sex-stratified PGS analyses were also performed. At the genome-wide level, ASD was positively correlated with allergic diseases (ALG), and negatively correlated with lymphocyte count, rheumatoid arthritis (RA), and systemic lupus erythematosus (SLE) (FDR-p = 0.01-0.02). At the local genetic level, ASD was correlated with RA, C-reactive protein, and granulocytes and lymphocyte counts (p = 5.8 × 10-6-0.002). In the general population sample, increased genetic liability for SLE, RA, ALG, and lymphocyte levels, captured by PGS, was associated with the total autistic score and with rigidity and childhood behaviour (FDR-p = 0.03). In conclusion, we demonstrated a genetic relationship between ASD and immunity that depends on the type of immune phenotype considered; some increase likelihood whereas others may potentially help build resilience. Also, this relationship may be restricted to specific genetic loci and link to specific autistic dimensions (e.g., rigidity).

Lycopene alleviates food allergy by modulating the PI3K/AKT pathway in peanut-sensitized BALB/c mice

Food allergies, which lead to life-threatening acute symptoms, are considered an important public health problem. Therefore, it is essential to develop efficient preventive and treatment measures. We developed a crude peanut protein extract (PPE)-induced allergy mouse model to investigate the effects of lycopene on peanut allergy. Mice were divided into four groups: 5 mg/kg lycopene, 20 mg/kg lycopene, no treatment, and control groups. Serum inflammatory factors were detected using enzyme-linked immunosorbent assay. In addition, pathology and immunohistochemistry analyses were used to examine the small intestine of mice. We found that lycopene decreased PPE-specific immunoglobulin E (IgE) and IL-13 levels in the serum, relieved small intestine inflammation, attenuated the production of histamine and mouse mast cell protease-1, and downregulated PI3K and AKT1 expression in the small intestine tissues of mice allergic to peanuts. Our results suggest that lycopene can ameliorate allergy by attenuating the PI3K/AKT pathway and the anaphylactic reactions mediated by PPE-specific IgE.

Multi-omics profiling approach in food allergy

The prevalence of food allergy (FA) among children is increasing, affecting nearly 8% of children, and FA is the most common cause of anaphylaxis and anaphylaxis-related emergency department visits in children. Importantly, FA is a complex, multi-system, multifactorial disease mediated by food-specific immunoglobulin E (IgE) and type 2 immune responses and involving environmental and genetic factors and gene-environment interactions. Early exposure to external and internal environmental factors largely influences the development of immune responses to allergens. Genetic factors and gene-environment interactions have established roles in the FA pathophysiology. To improve diagnosis and identification of FA therapeutic targets, high-throughput omics approaches have emerged and been applied over the past decades to screen for potential FA biomarkers, such as genes, transcripts, proteins, and metabolites. In this article, we provide an overview of the current status of FA omics studies, namely genomic, transcriptomic, epigenomic, proteomic, exposomic, and metabolomic. The current development of multi-omics integration of FA studies is also briefly discussed. As individual omics technologies only provide limited information on the multi-system biological processes of FA, integration of population-based multi-omics data and clinical data may lead to robust biomarker discovery that could translate into advances in disease management and clinical care and ultimately lead to precision medicine approaches.

Convergent Evidence Supports TH2LCRR as a Novel Asthma Susceptibility Gene

Asthma is a common complex disease with apparent genetic predispositions, and previous genome-wide association studies suggest that rs1295686 within the IL13 (interleukin 13) gene is significantly associated with asthma. Analysis of the data provided by the 1000 Genomes Project indicated that there are additional four SNPs in nearly complete linkage disequilibrium with rs1295686 in Caucasians. However, the causal SNPs and the associated mechanism remain unclear. To investigate this issue, functional genomics approaches were utilized to analyze the functions of these SNPs. Dual-luciferase assays indicated that the functional SNP is not rs1295686 but a haplotype consisting of other three SNPs, rs1295685, rs848 and rs847. Through chromosome conformation capture, it was found that the enhancer containing the three functional SNPs interacts with the promoter of TH2LCRR (T helper type 2 locus control region associated RNA), a recently identified long non-coding RNA. RNA-seq data analysis indicated that TH2LCRR expression is significantly increased in asthma patients and is dependent on the genotype at this locus, indicating that TH2LCRR is a novel susceptibility gene for asthma and that these SNPs confer asthma risk by regulating TH2LCRR expression. By chromatin immunoprecipitation, the related transcription factors that bind in the region surrounding these three SNPs were identified, and their interactions were investigated by functional genomics approaches. Our effort identified a novel mechanism through which genetic variations at this locus could influence asthma susceptibility.

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.

Children of Asian ethnicity in Australia have higher risk of food allergy and early-onset eczema than those in Singapore

BACKGROUND

In Western countries, Asian children have higher food allergy risk than Caucasian children. The early-life environmental exposures for this discrepancy are unclear. We aimed to compare prevalence of food allergy and associated risk factors between Asian children in Singapore and Australia.

METHODS

We studied children in the Growing Up in Singapore Towards healthy Outcomes (GUSTO) birth cohort (n = 878) and children of Asian ancestry in the HealthNuts cohort (n = 314). Food allergy was defined as a positive SPT ≥3 mm to egg or peanut AND either a convincing history of IgE-mediated reaction at 18 months (GUSTO) or a positive oral food challenge at 14-18 months (HealthNuts). Eczema was defined as parent-reported doctor diagnosis.

RESULTS

Food allergy prevalence was 1.1% in Singapore and 15.0% in Australia (P<0.001). Egg introduction was more often delayed (>10 months) in Singapore (63.5%) than Australia (16.3%; P<0.001). Prevalence of early-onset eczema (<6 months) was lower in Singapore (8.4%) than Australia (30.5%) (P<0.001). Children with early-onset eczema were more likely to have food allergy than those without eczema in Australia [aOR 5.11 (2.34-11.14); P<0.001] and Singapore [aOR4.00 (0.62-25.8); P = 0.145].

CONCLUSIONS

Among Asian children, prevalence of early-onset eczema and food allergy was higher in Australia than Singapore. Further research with larger sample sizes and harmonized definitions of food allergy between cohorts is required to confirm and extend these findings. Research on environmental factors influencing eczema onset in Australia and Singapore may aid understanding of food allergy pathogenesis in different parts of the world.

Anaphylaxis: Focus on Transcription Factor Activity

Anaphylaxis is a severe allergic reaction, rapid in onset, and can lead to fatal consequences if not promptly treated. The incidence of anaphylaxis has risen at an alarming rate in past decades and continues to rise. Therefore, there is a general interest in understanding the molecular mechanism that leads to an exacerbated response. The main effector cells are mast cells, commonly triggered by stimuli that involve the IgE-dependent or IgE-independent pathway. These signaling pathways converge in the release of proinflammatory mediators, such as histamine, tryptases, prostaglandins, etc., in minutes. The action and cell targets of these proinflammatory mediators are linked to the pathophysiologic consequences observed in this severe allergic reaction. While many molecules are involved in cellular regulation, the expression and regulation of transcription factors involved in the synthesis of proinflammatory mediators and secretory granule homeostasis are of special interest, due to their ability to control gene expression and change phenotype, and they may be key in the severity of the entire reaction. In this review, we will describe our current understanding of the pathophysiology of human anaphylaxis, focusing on the transcription factors' contributions to this systemic hypersensitivity reaction. Host mutation in transcription factor expression, or deregulation of their activity in an anaphylaxis context, will be updated. So far, the risk of anaphylaxis is unpredictable thus, increasing our knowledge of the molecular mechanism that leads and regulates mast cell activity will enable us to improve our understanding of how anaphylaxis can be prevented or treated.

Genetics of Food Allergy

The risk factors for food allergy (FA) include both genetic variants and environmental factors. Advances using both candidate-gene association studies and genome-wide approaches have led to the identification of FA-associated genes involved in immune responses and skin barrier functions. Epigenetic changes have also been associated with the risk of FA. In this chapter, we outline current understanding of the genetics, epigenetics and the interplay with environmental risk factors associated with FA. Future studies of gene-environment interactions, gene-gene interactions, and multi-omics integration may help shed light on the mechanisms of FA, and lead to improved diagnostic and treatment strategies.

Current insights into the genetics of food allergy

Food allergy (FA), a growing public health burden in the United States, and familial aggregation studies support strong roles for both genes and environment in FA risk. Deepening our understanding of the molecular and cellular mechanisms driving FAs is paramount to improving its prevention, diagnosis, and clinical management. In this review, we document lessons learned from the genetics of FA that have aided our understanding of these mechanisms. Although current genetic association studies suffer from low power, heterogeneity in definition of FA, and difficulty in our ability to truly disentangle FA from food sensitization (FS) and general atopy genetics, they reveal a set of genetic loci, genes, and variants that continue to implicate the importance of barrier and immune function genes across the atopic march, and FA in particular. The largest reported effects on FA are from MALT1 (odds ratio, 10.99), FLG (average odds ratio, ∼2.9), and HLA (average odds ratio, ∼2.03). The biggest challenge in the field of FA genetics is to elucidate the specific mechanism of action on FA risk and pathogenesis for these loci, and integrative approaches including genetics/genomics with transcriptomics, proteomics, and metabolomics will be critical next steps to translating these genetic insights into practice.

Association of HLA-DQ and IL13 gene variants with challenge-proven shrimp allergy in West Bengal, India

Little is known about genetic factors and mechanisms underlying shrimp allergy. Genome-wide association studies identified HLA class-II and IL13 genes as highly plausible candidates for shrimp allergy. The present study was designed to investigate potential associations of HLA-DQ rs9275596, IL13 rs20541, and IL13 rs1800925 polymorphisms with challenge-proven shrimp allergy using the data from 532 people of West Bengal, India; selected on basis of positive skin prick test, elevated specific IgE and medical history. Risk genotypes, i.e., HLA-DQ rs9275596 CC, IL13 rs20541 AA, and IL13 rs1800925 TT, were found to be significantly associated with challenge positive shrimp allergy (P = 0.04, 0.01, and 0.03, respectively). Distribution of genotypes for HLA-DQ and IL13 polymorphisms in allergic and control subjects showed significant difference between younger (20-40 years) and older (> 40 years) age group (P = 0.006). Risk genotypes significantly associated with elevated shrimp-specific IgE. IL13 TA haplotype significantly associated with shrimp allergy and elevated specific IgE (P = 0.02). Synergistic effect of IL13 TA haplotype-HLA-DQ rs9275596 CC genotype interaction significantly elevated specific IgE (P = 0.03). The present study suggests that HLA-DQ and IL13 polymorphisms pose major risk for shrimp allergic patients in West Bengal, India and thus could be helpful for early target-specific therapeutic intervention in near future.

The Global Rise and the Complexity of Sesame Allergy: Prime Time to Regulate Sesame in the United States of America?

Sesame allergy is a life-threatening disease that has been growing globally with poorly understood mechanisms. To protect sensitive consumers, sesame is regulated in many countries. There were four research goals for this work on sesame allergy: (i) to map the timeline, and the extent of its global rise; (ii) to dissect the complexity of the disease, and its mechanisms; (iii) to analyze the global regulation of sesame; and (iv) to map the directions for future research and regulation. We performed a literature search on PubMed and Google Scholar, using combinations of key words and analyzed the output. Regulatory information was obtained from the government agencies. Information relevant to the above goals was used to make interpretations. We found that: (i) the reports appeared first in 1950s, and then rapidly rose globally from 1990s; (ii) sesame contains protein and lipid allergens, a unique feature not found in other allergenic foods; (iii) it is linked to five types of diseases with understudied mechanisms; and (iv) it is a regulated allergen in 32 advanced countries excluding the USA. We also provide directions for filling gaps in the research and identify implications of possible regulation of sesame in the USA.

Food allergy prevention: current evidence

PURPOSE OF REVIEW

The aim of the article is to critically appraise the most relevant studies in the rapidly advancing field of food allergy prevention.

RECENT FINDINGS

Epidemiologic studies identified atopic dermatitis as a strong risk factor for food allergy, with mounting evidence for impaired skin barrier and cutaneous inflammation in the pathogenesis. Additional risk factors include a family history of atopy, the timing of allergenic food introduction into the infant's diet, dietary diversity, vitamin D, and environmental factors, such as dog ownership. Early introduction of allergenic foods (such as peanut) into the infant diet was shown to significantly reduce the risk of food allergy in infants with risk factors, whereas studies targeting skin barrier function have produced conflicting results. Cumulative evidence supports dietary diversity during pregnancy, breastfeeding, infancy, and early childhood.

SUMMARY

A variety of interventions have been evaluated for the prevention of atopic dermatitis and food allergy, often producing conflicting results. At present, official guidelines encourage breastfeeding and early allergenic food introduction for infants at risk for food allergy, with an emphasis on dietary diversity, fruits, vegetables, fish, and food sources of vitamin D during pregnancy, lactation, and early life for all infants.

Association of IL13 genetic polymorphisms with atopic dermatitis: Fine mapping and haplotype analysis

BACKGROUND

Although previous studies had reported an important role of interleukin 13 (IL13) and its genetic polymorphisms in atopic dermatitis (AD), many of these previous reports focused on the missense variant rs20541 (Gln144Arg) without fine mapping of the gene region.

OBJECTIVE

To analyze the potential associations of other IL13 variants and their haplotypes with AD and assess total serum immunoglobulin E (IgE) levels.

METHODS

We performed fine mapping of single-nucleotide polymorphisms (SNPs) within the IL13 gene in a pilot study of 495 children with AD and 444 healthy controls. Then, we conducted a replication study of 757 children with AD and 1620 healthy controls to evaluate the association between the rs20541 variant of IL13 and AD.

RESULTS

In the pilot study, the rs20541 and rs1295685 SNPs in the 3'-untranslated region of IL13 had significant associations with AD (P < .001 and .01, respectively). In addition, 2 haplotypes (BL2_ht1 and BL2_ht2), which harbored the significant rs20541 and rs1295685 SNPs, had an association with AD (minimum P = .006). BL2_ht1 and BL2_ht2 had nominal signals associated with the total serum IgE levels (P < .05) but not with the severity of AD (P > .05). In the replication study, rs20541 was associated with the total serum IgE levels but not with the severity of AD.

CONCLUSION

An additional IL13 gene SNP, rs1295685, has a strong linkage disequilibrium with rs20541, and its haplotypes are associated with AD and the total serum IgE levels.

Genetic determinants of paediatric food allergy: A systematic review

BACKGROUND

The genetic determinants of food allergy have not been systematically reviewed. We therefore systematically reviewed the literature on the genetic basis of food allergy, identifying areas for further investigation.

METHODS

We searched three electronic databases (MEDLINE, EMBASE and PubMed) on 9 January 2018. Two authors screened retrieved articles for review according to inclusion criteria and extracted relevant information on study characteristics and measures of association. Eligible studies included those that reported an unaffected nonatopic control group, had genetic information and were carried out in children.

RESULTS

Of the 2088 studies retrieved, 32 met our inclusion criteria. Five were genome-wide association studies, and the remaining were candidate gene studies. Twenty-two of the studies were carried out in a predominantly Caucasian population with the remaining 10 from Asian-specific populations or unspecified ethnicity. We found FLG, HLA, IL10, IL13, as well as some evidence for other variants (SPINK5, SERPINB and C11orf30) that are associated with food allergy.

CONCLUSIONS

Little genetic research has been carried out in food allergy, with FLG, HLA and IL13 being the most reproducible genes for an association with food allergy. Despite promising results, existing genetic studies on food allergy are inundated with issues such as inadequate sample size and absence of multiple testing correction. Few included replication analyses or population stratification measures. Studies addressing these limitations along with functional studies are therefore needed to unravel the mechanisms of action of the identified genes.

Identification of a T follicular helper cell subset that drives anaphylactic IgE

Cross-linking of high-affinity immunoglobulin E (IgE) results in the life-threatening allergic reaction anaphylaxis. Yet the cellular mechanisms that induce B cells to produce IgE in response to allergens remain poorly understood. T follicular helper (T_FH) cells direct the affinity and isotype of antibodies produced by B cells. Although T_FH cell-derived interleukin-4 (IL-4) is necessary for IgE production, it is not sufficient. We report a rare population of IL-13-producing T_FH cells present in mice and humans with IgE to allergens, but not when allergen-specific IgE was absent or only low-affinity. These "T_FH13" cells have an unusual cytokine profile (IL-13^hiIL-4^hiIL-5^hiIL-21^lo) and coexpress the transcription factors BCL6 and GATA3. T_FH13 cells are required for production of high- but not low-affinity IgE and subsequent allergen-induced anaphylaxis. Blocking T_FH13 cells may represent an alternative therapeutic target to ameliorate anaphylaxis.

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.

Bifidobacterium lactis Ameliorates the Risk of Food Allergy in Chinese Children by Affecting Relative Percentage of Treg and Th17 Cells

We aimed to explore the therapeutic effect of Bifidobacterium lactis on food allergy by investigating the percentage of Treg and Th17 cells in Chinese children and related molecular mechanisms. A total of 256 children with food allergy were evenly assigned into two groups: BG, the children received 10 ml B. lactis (1 × 10⁶/ml) daily, and CG, the children received the solution without B. lactis daily for three months. Allergic symptoms, serum IgE, and food antigen-specific IgE were measured. A mouse allergy model was established by using shrimp tropomyosin and treated with B. lactis. Relative mRNA levels of Treg- and Th17-associated cytokines were measured by using quantitative PCR. The percentage of Treg and Th17 cells in spleen were measured by using flow cytometry. After 3-month therapy, the allergic symptoms of the BG were remarkably reduced when compared with the CG (P < 0.05). Serum levels of IgE and food antigen-specific IgE were decreased too (P < 0.05). Similar results were also found in a mouse allergy model. After B. lactis treatment, the relative mRNA level of FoxP3 was significantly enhanced in the B. lactis therapy group when compared to positive controls. In addition, relative mRNA levels of FoxP3 and TGF-β associated with Treg cells were increased, whereas relative mRNA levels of IL-17A and IL-23 associated with Th17 were reduced. B. lactis treatment significantly increased the ratio of Treg and Th17 cells in a mouse allergy model (P < 0.05). B. lactis effectively alleviates allergic symptoms by increasing the ratio of Treg and Th17 cells.

Cellular and molecular mechanisms of vitamin D in food allergy

Food allergies are becoming increasingly prevalent, especially in young children. Epidemiological evidence from the past decade suggests a role of vitamin D in food allergy pathogenesis. Links have been made between variations in sunlight exposure, latitude, birth season and vitamin D status with food allergy risk. Despite the heightened interest in vitamin D in food allergies, it remains unclear by which exact mechanism(s) it acts. An understanding of the roles vitamin D plays within the immune system at the cellular and genetic levels, as well as the interplay between the microbiome and vitamin D, will provide insight into the importance of the vitamin in food allergies. Here, we discuss the effect of vitamin D on immune cell maturation, differentiation and function; microbiome; genetic and epigenetic regulation (eg DNA methylation); and how these processes are implicated in food allergies.

Candidate Gene Testing in Clinical Cohort Studies with Multiplexed Genotyping and Mass Spectrometry

Complex diseases are often underpinned by multiple common genetic variants that contribute to disease susceptibility. Here, we describe a cost-effective tag single nucleotide polymorphism (SNP) approach using a multiplexed genotyping assay with mass spectrometry, to investigate gene pathway associations in clinical cohorts. We investigate the food allergy candidate locus Interleukin13 (IL13) as an example. This method efficiently maximizes the coverage by taking advantage of shared linkage disequilibrium (LD) within a region. Selected LD SNPs are then designed into a multiplexed assay, enabling up to 40 different SNPs to be analyzed simultaneously, boosting cost-effectiveness. Polymerase chain reaction (PCR) is used to amplify the target loci, followed by single nucleotide extension, and the amplicons are then measured using matrix-assisted laser desorption/ionization-time of flight(MALDI-TOF) mass spectrometry. The raw output is analyzed with the genotype calling software, using stringent quality control definitions and cut-offs, and high probability genotypes are determined and output for data analysis.

Advances in the approach to the patient with food allergy

Advances in food allergy diagnosis, management, prevention, and therapeutic interventions have been significant over the past 2 decades. Evidence-based national and international guidelines have streamlined food allergy diagnosis and management, whereas paradigm-shifting work in primary prevention of peanut allergy has resulted in significant modifications in the approach to early food introduction in infants and toddlers. Innovative investigation of food allergy epidemiology, systems biology, effect, and management has provided important insights. Although active therapeutic approaches to food allergy remain experimental, progress toward licensed therapies has been substantial. Mechanistic understanding of the immunologic processes underlying food allergy and immunotherapy will inform the future design of therapeutic approaches targeting the food-induced allergic response. Global strategies to mitigate the substantial medical, economic, and psychosocial burden of food allergy in affected subjects and families will require engagement of stakeholders across multiple sectors in research, health care, public health, government, educational institutions, and industry. However, the relationship between the well-informed allergy care provider and the patient and family remains fundamental for optimizing the care of the patient with food allergy.

Immunological Changes Induced in Peach Allergy Patients with Systemic Reactions by Pru p 3 Sublingual Immunotherapy

SCOPE

Sublingual immunotherapy using peach extract enriched in Pru p 3 (Pru p 3-enriched-SLIT) brings a new perspective to treating patients with allergy to lipid transfer proteins. We evaluate the immunological changes induced by Pru p 3-enriched-SLIT during one year.

METHODS AND RESULTS

Three groups are included: peach allergic patients who receive Pru p 3-enriched-SLIT, peach allergic untreated patients, and controls. Peripheral blood mononuclear cells are obtained before treatment and at different time-points. Monocyte-derived dendritic cells (moDCs) maturation and lymphocyte proliferation are assessed by flow cytometry. Data showed a significant reduction of moDCs maturation status during one year of treatment and an increase in PD-L1. Moreover, we observed a significant decrease of the Pru p 3-specific proliferation of effector cells and an increase in regulatory T (Treg) cells with higher PD-L1 expression and IL-10 production. These are observed in patients treated only.

CONCLUSION

Successful Pru p 3-enriched-SLIT is linked to an important immunosuppression of allergen-specific effector T cells, potentially due to an increase of allergen-specific Treg cells. These cellular changes are orchestrated by the activity of moDCs promoting the expression of PD-L1 that will participate in the regulatory response. These changes may serve as biomarkers during SLIT alongside other features such as IgE/IgG₄ ratio.

How Different Parts of the World Provide New Insights Into Food Allergy

The prevalence and patterns of food allergy are highly variable in different parts of the world. Differences in food allergy epidemiology may be attributed to a complex interplay of genetic, epigenetic, and environmental factors, suggesting that mechanisms of food allergy may differ in various global populations. Genetic polymorphisms, migration, climate, and infant feeding practices all modulate food allergy risk, and possibly also the efficacy of interventions aimed at primary prevention of food allergy development. Approaches to diagnosis, treatment, and prevention of food allergy should thus be tailored carefully to each population's unique genetic and environmental make-up. Future research in the context of food allergy prevention should focus on elucidating factors determining differential responses between populations.

Association of IL-13 rs20541 and rs1295686 variants with symptomatic asthma in a Saudi Arabian population

OBJECTIVE

Interleukin 13 (IL-13) plays a critical pro-inflammatory role in asthma. Several single nucleotide polymorphisms (SNPs) are associated with asthma susceptibility in specific populations; however, further replicative studies in other ethnic groups are mandatory.

METHODS

The association between IL-13 SNPs rs762534, rs20541, rs1295686, and rs1800925 (risk alleles A, A, T, and A, respectively) and asthma predisposition in a Saudi Arabian cohort was examined via a case-control cross-sectional study.

RESULTS

The frequencies of alleles between asthmatics and control populations were significantly different for rs20541 and rs1295686 SNPs (p < 0.001), whereas the frequencies of genotypes between asthmatics and controls were significantly different only for rs20541. The association of the risk (minor) alleles with asthma was examined using the dominant genetic model. Individuals with at least one copy of the risk alleles A (for rs20541) and T (for rs1295686) had significantly greater odds of being asthmatic (OR = 2.13, 95% CI = 1.39-3.26, p < 0.0001; OR = 1.69, 95% CI = 1.12-2.54, p = 0.008) relative to their most common homozygous genotypes. On the other hand, the minor A alleles for rs762534 and rs1800925 were not significantly associated with asthma risk. Regarding haplotype association analysis, individuals with at least one copy of the minor "risk" allele for both rs20541 and rs1295686 (CATG and CATA, respectively) had greater odds of being asthmatic relative to CGCG haplotype; however, this trend was not statistically significant (p > 0.3).

CONCLUSIONS

IL-13 minor T and A alleles for rs1295686 and rs20541, respectively, were associated with significantly higher risk of asthma in the Saudi Arabian population.

Genetic associations with adverse events from anti-tumor necrosis factor therapy in inflammatory bowel disease patients

AIM

To study the type and frequency of adverse events associated with anti-tumor necrosis factor (TNF) therapy and evaluate for any serologic and genetic associations.

METHODS

This study was a retrospective review of patients attending the inflammatory bowel disease (IBD) centers at Cedars-Sinai IBD Center from 2005-2016. Adverse events were identified via chart review. IBD serologies were measured by ELISA. DNA samples were genotyped at Cedars-Sinai using Illumina Infinium Immunochipv1 array per manufacturer’s protocol. SNPs underwent methodological review and were evaluated using several SNP statistic parameters to ensure optimal allele-calling. Standard and rigorous QC criteria were applied to the genetic data, which was generated using immunochip. Genetic association was assessed by logistic regression after correcting for population structure.

RESULTS

Altogether we identified 1258 IBD subjects exposed to anti-TNF agents in whom Immunochip data were available. 269/1258 patients (21%) were found to have adverse events to an anti-TNF-α agent that required the therapy to be discontinued. 25% of women compared to 17% of men experienced an adverse event. All adverse events resolved after discontinuing the anti-TNF agent. In total: n = 66 (5%) infusion reactions; n = 49 (4%) allergic/serum sickness reactions; n = 19 (1.5%) lupus-like reactions, n = 52 (4%) rash, n = 18 (1.4%) infections. In Crohn’s disease, IgA ASCA (P = 0.04) and IgG-ASCA (P = 0.02) levels were also lower in patients with any adverse events, and anti-I2 level in ulcerative colitis was significantly associated with infusion reactions (P = 0.008). The logistic regression/human annotation and network analyses performed on the Immunochip data implicated the following five signaling pathways: JAK-STAT (Janus Kinase-signal transducer and activator of transcription), measles, IBD, cytokine-cytokine receptor interaction, and toxoplasmosis for any adverse event.

CONCLUSION

Our study shows 1 in 5 IBD patients experience an adverse event to anti-TNF therapy with novel serologic, genetic , and pathways associations.