Food allergy diagnosis and therapy: where are we now?

TCR sequencing paired with massively parallel 3' RNA-seq reveals clonotypic T cell signatures

High-throughput 3' single-cell RNA-sequencing (scRNA-seq) allows cost-effective, detailed characterization of individual immune cells from tissues. Current techniques, however, are limited in their ability to elucidate essential immune cell features, including variable sequences of T cell antigen receptors (TCRs) that confer antigen specificity. Here, we present a strategy that enables simultaneous analysis of TCR sequences and corresponding full transcriptomes from 3'-barcoded scRNA-seq samples. This approach is compatible with common 3' scRNA-seq methods, and adaptable to processed samples post hoc. We applied the technique to identify transcriptional signatures associated with T cells sharing common TCRs from immunized mice and from patients with food allergy. We observed preferential phenotypes among subsets of expanded clonotypes, including type 2 helper CD4⁺ T cell (T_H2) states associated with food allergy. These results demonstrate the utility of our method when studying diseases in which clonotype-driven responses are critical to understanding the underlying biology.

Food Allergy Knowledge and Attitudes Among School Teachers in Jazan, Saudi Arabia

Background:

Food allergy topic has become more widely discussed in developed countries, but with less interest in Middle Eastern Arabian Countries.

Objectives:

The main objective of this paper is to assess the knowledge and perception of schoolteachers about food allergy.

Methods:

A cross sectional study was conducted among a sample of 360 school teachers between May 2013 and February 2014 in province of Jazan in Saudi Arabia, using a validated web-based self-administered survey.

Results:

The results revealed that almost (59.7%) of the schoolteachers had a medium insufficient knowledge about food allergy; only 17.3% had good knowledge about food allergy. Female teachers had higher knowledge scores (58.5 ± 17.2) as compared to male (51.8 ± 16.0) with statistically significant difference (p = 0.017). The majority of schoolteachers have a significantly poor knowledge in most of food allergy domains. More than half of responders either do not know or they disagree that the food allergy is a serious problem and can lead to death. Regression analysis revealed that participant’s level of knowledge is significantly associated with school teacher’s attitudes towards food allergy (OR = 0.06, 95% CI: 0.39 - 0.92, p = 0.01), practice (OR = 1.68, 95% CI: 1.11 - 2.56, p = 0.01), and years of experiences (OR = 1.8, 95% CI; 1.15 - 2.98, p = 0.011).

Conclusion:

Knowledge of food allergy among schoolteachers is not adequate, failing to recognize and treat fatal food allergy reactions necessitate an urgent need to set a school policy to improve the food allergy situation.

Cocoa Diet Prevents Antibody Synthesis and Modifies Lymph Node Composition and Functionality in a Rat Oral Sensitization Model

Cocoa powder, a rich source of polyphenols, has shown immunomodulatory properties in both the intestinal and systemic immune compartments of rats. The aim of the current study was to establish the effect of a cocoa diet in a rat oral sensitization model and also to gain insight into the mesenteric lymph nodes (MLN) activities induced by this diet. To achieve this, three-week-old Lewis rats were fed either a standard diet or a diet with 10% cocoa and were orally sensitized with ovalbumin (OVA) and with cholera toxin as a mucosal adjuvant. Specific antibodies were quantified, and lymphocyte composition, gene expression, and cytokine release were established in MLN. The development of anti-OVA antibodies was almost totally prevented in cocoa-fed rats. In addition, this diet increased the proportion of TCRγδ+ and CD103+CD8+ cells and decreased the proportion of CD62L+CD4+ and CD62L+CD8+ cells in MLN, whereas it upregulated the gene expression of OX40L, CD11c, and IL-1β and downregulated the gene expression of IL-17α. In conclusion, the cocoa diet induced tolerance in an oral sensitization model accompanied by changes in MLN that could contribute to this effect, suggesting its potential implication in the prevention of food allergies.

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.

The future of biologics: applications for food allergy

Allergic diseases affect millions worldwide, with growing evidence of an increase in allergy occurrence over the past few decades. Current treatments for allergy include corticosteroids to reduce inflammation and allergen immunotherapy; however, some subjects experience treatment-resistant inflammation or adverse reactions to these treatments, and there are currently no approved therapeutics for the treatment of food allergy. There is a dire need for new therapeutic approaches for patients with poorly controlled atopic diseases and a need to improve the safety and effectiveness of allergen immunotherapy. Improved understanding of allergy through animal models and clinical trials has unveiled potential targets for new therapies, leading to the development of several biologics to treat allergic diseases. This review focuses on the mechanisms that contribute to allergy, with an emphasis on future targets for biologics for the treatment of food allergy. These biologics include immunotherapy with novel anti-IgE antibodies and analogs, small-molecule inhibitors of cell signaling, anti-type 2 cytokine mAbs, and TH1-promoting adjuvants.

Lessons learned from mice and man: mimicking human allergy through mouse models

The relevance of using mouse models to represent human allergic pathologies is still unclear. Recent studies suggest the limitations of using models as a standard for assessing immune response and tolerance mechanisms, as mouse models often do not sufficiently depict human atopic conditions. Allergy is a combination of aberrant responses to innocuous environmental agents and the subsequent TH2-mediated inflammatory responses. In this review, we will discuss current paradigms of allergy - specifically, TH2-mediated and IgE-associated immune responses - and current mouse models used to recreate these TH2-mediated pathologies. Our overall goal is to highlight discrepancies that exist between mice and men by examining the advantages and disadvantages of allergic mouse models with respect to the human allergic condition.

Modulation of immune responses by immunotherapy in allergic diseases

Allergen immunotherapy (AIT) has been used for 100 years and until now different immunoregulatory pathways have been shown to take place in its mechanisms of action. It is characterized by administration of the causative allergen and is shown to be clinically efficient even after discontinuation of therapy particularly in allergic respiratory diseases, bee venom allergy, and food allergy. Generation of antigen/allergen-specific peripheral tolerance is the key mechanism during immunotherapy. It is mediated by development of T and B regulatory cells, IgG4 isotype allergen-specific antibodies and the involvement of multiple suppressor factors, which lead to decreased tissue inflammation, early and late phase responses. Describing novel regulatory mechanisms in the process of immune tolerance induction will help to identify treatment modalities not only for allergic disorders, but also for autoimmune diseases, organ transplantation, chronic infections, and cancer.

Regulatory T cells and their roles in immune dysregulation and allergy

The main function of the immune system is to fight off potential infections, but also to maintain its activity below a level that would trigger self-reactivity. Regulatory T cells (Tregs) such as forkhead box P3(+) (FOXP3) Tregs and type 1 regulatory T cells (Tr1) play an essential role in this active process, using several distinct suppressive mechanisms. A wide range of pathologies have been associated with altered Treg cell function. This is best exemplified by the impact of mutations of genes essential for Treg function and the associated autoimmune syndromes. This review summarizes the main features of different subtypes of Tregs and focuses on the clinical implications of their altered function in human studies. More specifically, we discuss abnormalities affecting FOXP3(+) Tregs and Tr1 cells that will lead to autoimmune manifestations and/or allergic reactions, and the potential therapeutic use of Tregs.