The Prevalence and Natural History of Food Allergy

Natural course of IgE-mediated food allergy in children

The prevalence of food allergy and food-induced anaphylaxis in children is increasing worldwide. Cow's milk, hen's eggs, and wheat allergies in young children have a more favorable prognosis with a relatively early outgrow, while allergies to peanuts, tree nuts, and seafood are more likely to be persistent. Although our understanding of the mechanism underlying the resolution of food allergy is incomplete, the roles of dendritic cells, regulatory T cells, and regulatory B cells are important. Many past studies on the natural course of food allergy were retrospective analyses of specific study groups, but large-scale population-based prospective studies are now being published. This review summarizes recent studies of the natural course of cow's milk, hen's eggs, wheat, peanuts, tree nuts, soy, sesame, and seafood allergies. The potential factors affecting the natural course of food allergy include symptom severity on ingestion, age at diagnosis, allergic comorbidities, skin prick test reaction size or serum food-specific immunoglobulin (Ig) E levels, changes in sensitization degree, IgE epitope specificity, ratio of food-specific IgE to IgG4, food-specific IgA levels, component-resolved diagnostic profile, diet, gut microbiome, and interventions such as immunotherapy. Since food allergy places a significant burden on patients and their caregivers in daily life, clinicians should be able to provide relevant knowledge on the natural course of food allergy, appropriately evaluate its resolution, and offer therapeutic options whenever possible.

The origins and longevity of IgE responses as indicated by serological and cellular studies in mice and humans

The existence of long-lived IgE antibody-secreting cells (ASC) is contentious, with the maintenance of sensitization by the continuous differentiation of short-lived IgE+ ASC a possibility. Here, we review the epidemiological profile of IgE production, and give an overview of recent discoveries made on the mechanisms regulating IgE production from mouse models. Together, these data suggest that for most individuals, in most IgE-associated diseases, IgE+ ASC are largely short-lived cells. A subpopulation of IgE+ ASC in humans is likely to survive for tens of months, although due to autonomous IgE B cell receptor (BCR) signaling and antigen-driven IgE+ ASC apoptosis, in general IgE+ ASC probably do not persist for the decades that other ASC are inferred to do. We also report on recently identified memory B cell transcriptional subtypes that are the likely source of IgE in ongoing responses, highlighting the probable importance of IL-4Rα in their regulation. We suggest the field should look at dupilumab and other drugs that prohibit IgE+ ASC production as being effective treatments for IgE-mediated aspects of disease in most individuals.

Reduction in Allergenicity and Induction of Oral Tolerance of Glycated Tropomyosin from Crab

Tropomyosin (TM) is an important crustacean (Scylla paramamosain) allergen. This study aimed to assess Maillard-reacted TM (TM-G) induction of allergenic responses with cell and mouse models. We analyzed the difference of sensitization and the ability to induce immune tolerance between TM and TM-G by in vitro and in vivo models, then we compared the relationship between glycation sites of TM-G and epitopes of TM. In the in vitro assay, we discovered that the sensitization of TM-G was lower than TM, and the ability to stimulate mast cell degranulation decreased from 55.07 ± 4.23% to 27.86 ± 3.21%. In the serum of sensitized Balb/c mice, the level of specific IgE produced by TM-G sensitized mice was significantly lower than TM, and the levels of interleukins 4 and interleukins 13 produced by Th2 cells in spleen lymphocytes decreased by 82.35 ± 5.88% and 83.64 ± 9.09%, respectively. In the oral tolerance model, the ratio of Th2/Th1 decreased from 4.05 ± 0.38 to 1.69 ± 0.19. Maillard reaction masked the B cell epitopes of TM and retained some T cell epitopes. Potentially, Maillard reaction products (MRPs) can be used as tolerance inducers for allergen-specific immunotherapy.

Food Allergy Prevention: Early Versus Late Introduction of Food Allergens in Children

The emergence of food allergies in children is crucial for various medical fields seeking a viable strategy for allergy prevention. The most well-recognized approach adopted by numerous health care and government institutions hinges on the delay in the introduction of food allergens, which supposedly protects infants from sensitization and decreases the possibility of allergy development. However, recent experimental findings indicate that the benefits of this approach might be overestimated, as early exposure to allergenic foods has been shown to yield more advantageous outcomes. Multiple investigations on the causes of allergic diseases report that avoiding food allergies might be related to early consumption of these allergens. Alternatively, delaying the contact with allergenic nourishments, explored in contemporary research, has been proven to result in a higher prevalence of allergies among children, originating such conditions as atopic diseases and extreme sensitization to foods. The current paper compares the two prominent strategies of allergenic food introduction, gathering the most pertinent modern evidence to distinguish whether exposure to food allergens should be delayed or advanced.

The Fermented Soy Product ImmuBalanceTM Suppresses Airway Inflammation in a Murine Model of Asthma

The fermented soy product ImmuBalance contains many active ingredients and its beneficial effects on some allergic diseases have been reported. We hypothesized that ImmuBalance could have potential effects on airway inflammation in a murine model of asthma. Mice sensitized and challenged with ovalbumin developed airway inflammation. Bronchoalveolar lavage fluid was assessed for inflammatory cell counts and levels of cytokines. Lung tissues were examined for cell infiltration and mucus hypersecretion. Oral administration of ImmuBalance significantly inhibited ovalbumin-induced eosinophilic inflammation and decreased Th2 cytokine levels in bronchoalveolar lavage fluid (p < 0.05). In addition, lung histological analysis showed that ImmuBalance inhibited inflammatory cell infiltration and airway mucus production. Our findings suggest that supplementation with ImmuBalance may provide a novel strategy for the prevention or treatment of allergic airway inflammation.

Stem Cell Factor Neutralization Protects From Severe Anaphylaxis in a Murine Model of Food Allergy

Food allergy is a growing public health problem with ~15 million people affected in the United States. In allergic food disease, IgE on mast cells bind to ingested antigens leading to the activation and degranulation of mast cells. Stem cell factor (SCF) is mast cell growth and activation factor that is required for peripheral tissue mast cells. We targeted a specific isoform of SCF, the larger 248 amino acid form, that drives peripheral tissue mast cell differentiation using a specific monoclonal antibody in a model of food allergy. Ovalbumin sensitized and intragastrically challenged mice were monitored for symptoms of anaphylaxis including respiratory distress, diarrhea, and a reduction in body temperature. During the second week of challenges, allergic mice were injected with an antibody to block SCF248 or given IgG control. Mice treated with α-SCF248 had a decreased incidence of diarrhea and no reduction in body temperature suggesting a reduction in anaphylaxis compared to IgG control treated animals. Re-stimulated mesenteric lymph nodes indicated that α-SCF248 treated mice had decreased OVA-specific Th2 cytokine production compared to IgG control treated allergic animals. The reduction of food induced anaphylaxis was accompanied by a significant reduction in gut leak. The mesenteric lymph node cells were analyzed by flow cytometry and showed a decrease in the number of type 2 innate lymphoid cells in mice injected with α-SCF248. Morphometric enumeration of esterase+ mast cells demonstrated a significant reduction throughout the small intestine. Using a more chronic model of persistent food-induced anaphylaxis, short term therapeutic treatment with α-SCF248 during established disease effectively blocked food induced anaphylaxis. Together, these data suggest that therapeutically blocking SCF248 in food allergic animals can reduce the severity of food allergy by reducing mast cell mediated disease activation.

Overcoming Shellfish Allergy: How Far Have We Come?

Shellfish allergy caused by undesirable immunological responses upon ingestion of crustaceans and mollusks is a common cause of food allergy, especially in the Asia-Pacific region. While the prevalence of shellfish allergy is increasing, the mainstay of clinical diagnosis for these patients includes extract-based skin prick test and specific IgE measurement while clinical management consists of food avoidance and as-needed use of adrenaline autoinjector should they develop severe allergic reactions. Such a standard of care is unsatisfactory to both patients and healthcare practitioners. There is a pressing need to introduce more specific diagnostic methods, as well as effective and safe therapies for patients with shellfish allergy. Knowledge gained on the identifications and defining the immuno-molecular features of different shellfish allergens over the past two decades have gradually translated into the design of new diagnostic and treatment options for shellfish allergy. In this review, we will discuss the epidemiology, the molecular identification of shellfish allergens, recent progress in various diagnostic methods, as well as current development in immunotherapeutic approaches including the use of unmodified allergens, hypoallergens, immunoregulatory peptides and DNA vaccines for the prevention and treatment of shellfish allergy. The prospect of a “cure “for shellfish allergy is within reach.

Influence of heat treatment and egg matrix on the physicochemical and allergenic properties of egg custard

To investigate the influence of heat treatment and egg matrix on egg custard (EC) proteins, 12 different kinds of ECs with different egg/water ratios (1:1, 1:1.5, 1:2, or 1:3, v/v) and different heating temperatures (80, 90, or 100 °C) and times (10, 15, or 20 min) were prepared and evaluated for the digestibility, structure, eliciting capacity and sensitizing capacity using SDS-PAGE, fluorescence spectra, ELISA, and a BALB/c mouse model, respectively. The physicochemical properties of EC proteins were significantly affected by heat treatment and egg matrix, which showed the increased digestibility and partially unfolded structure. The eliciting capacity of EC evaluated by IgE binding to sera from egg-allergic patients was reduced after heat treatment, and the EC made by heating at 100 °C for 20 min with a whole egg/water ratio of 1:2 (v/v) was the weakest. The sensitizing capacity of EC was also reduced in the BALB/c mouse model, which showed the significantly decreased levels of specific IgE, IgG, IgG1 and IgG2a, mMCP-1 and histamine in the mouse sera, as well as cytokine secretions of IL-4, IL-5, and IL-13, compared with the raw egg (RE) group. Results demonstrate that heat treatment and egg matrix significantly reduced the eliciting and sensitizing capacity of EC by changing the tertiary structure and increasing the digestibility of EC proteins. PRACTICAL APPLICATION: Egg custard (EC) is one kind of savory food suitable for all ages, and is also a traditional supplementary food for infants and young children in China. However, limited information is available on the allergenicity of egg custard. In this work, we evaluated how the structure, digestibility, and allergenic potential of egg allergens in EC were altered by the degree of thermal treatment and egg matrix, and elucidated the links between the physicochemical properties and allergenic potential of EC affected by heat treatment and egg matrix. Our results demonstrate that heat treatment and egg matrix significantly reduced the eliciting and sensitizing capacity of EC by changing the tertiary structure and increasing the digestibility of EC proteins.

Epidemiology of Cow's Milk Allergy

Immunoglobulin E (IgE)-mediated cow's milk allergy (CMA) is one of the most common food allergies in infants and young children. CMA can result in anaphylactic reactions, and has long term implications on growth and nutrition. There are several studies in diverse populations assessing the epidemiology of CMA. However, assessment is complicated by the presence of other immune-mediated reactions to cow's milk. These include non-IgE and mixed (IgE and non-IgE) reactions and common non-immune mediated reactions, such as lactose intolerance. Estimates of prevalence and population-level patterns are further complicated by the natural history of CMA (given its relatively high rate of resolution) and variation in phenotype (with a large proportion of patients able to tolerate baked cow's milk). Prevalence, natural history, demographic patterns, and long-term outcomes of CMA have been explored in several disparate populations over the past 30 to 40 years, with differences seen based on the method of outcome assessment, study population, time period, and geographic region. The primary aim of this review is to describe the epidemiology of CMA. The review also briefly discusses topics related to prevalence studies and specific implications of CMA, including severity, natural course, nutritional impact, and risk factors.

Acquisition, remission, and persistence of eczema, asthma, and rhinitis in children

BACKGROUND

Allergic sensitization is associated with eczema, asthma, and rhinitis. However, it is unknown whether and how allergic sensitization is associated over time with acquisition, remission, and persistence of these diseases and their comorbidity.

OBJECTIVE

To gain a better understanding of factors including allergic sensitization transitions that influence the temporal pattern of asthma, eczema, and rhinitis and their comorbidity during childhood.

METHODS

In the Isle of Wight birth cohort, information on allergic sensitization to common allergens was collected at ages 4, 10, and 18 years along with asthma, rhinitis, and eczema status determined by clinical diagnosis. Logistic regressions were used to estimate subsequent and concurrent odds ratios of diseases transition with allergic sensitization transition status as the main independent variable. Two transition periods were considered, 4 to 10 years of age and 10 to 18 years of age.

RESULTS

The odds of new diagnosis of allergic disease (no-yes) was increased among subjects with acquired or persistent allergic sensitization to common allergens compared to subjects with no sensitization (acquisition of sensitization odds ratio [OR]=3.22, P < .0001; persistence of sensitization, OR=6.33, P < .0001). The odds of remission of allergic diseases (yes-no) was lower among subjects with acquired or sustained allergic sensitization (acquisition, OR=0.18, P = .0001; persistence, OR=0.085, P < .0001), compared to subjects not sensitized. Subjects with acquired or persistent allergic sensitization were also had higher odds for persistence of disease (yes-yes) than subjects not sensitized (acquisition, OR=5.49, P = .0001; persistence, OR=11.79, P < .0001).

CONCLUSION

Transition of allergic sensitizations to common allergens is a prognostic factor for subsequent or concurrent transition of eczema, asthma, and rhinitis. Prevention or reduction in allergic sensitization has a potential to lead to remission of these conditions.

Food-Induced Acute Pancreatitis

Food allergy, a commonly increasing problem worldwide, defined as an adverse immune response to food. A variety of immune-related effector cells such as mast cells, eosinophils, neutrophils, and T cells are involved in food-related allergic responses categorized as IgE mediated, non-IgE mediated, and mixed (IgE and non-IgE) depending upon underlying immunological mechanisms. The dietary antigens mainly target the gastrointestinal tract including pancreas that gets inflamed due to food allergy and leads acute pancreatitis. Reports indicate several food proteins induce pancreatitis; however, detailed underlying mechanism of food-induced pancreatitis is unexplored. The aim of the review is to understand and update the current scenario of food-induced pancreatitis. A comprehensive literature search of relevant research articles has been performed through PubMed, and articles were chosen based on their relevance to food allergen-mediated pancreatitis. Several cases in the literature indicate that acute pancreatitis has been provoked after the consumption of mustard, milk, egg, banana, fish, and kiwi fruits. Food-induced pancreatitis is an ignored and unexplored area of research. The review highlights the significance of food in the development of pancreatitis and draws the attention of physicians and scientists to consider food allergies as a possible cause for initiation of pancreatitis pathogenesis.

Vitamin D-deficiency induces eosinophil spontaneous activation

Eosinophils (Eo) play a critical role in immunity and immune inflammation. The maintenance of Eo homeostasis is not fully understood yet. Vitamin D (VitD) is involved in the regulation of a large number of biochemical reactions. This study tests a hypothesis that VitD receptor (VDR) contributes to the homeostasis of Eos. In this study, EoL-1 cells (an Eo cell line) were cultured in the presence or absence of calcitriol. The Eo-mediators, including major basic protein (MBP), Eo peroxidase (EPX), Eo cationic protein (ECP) and Eo-derived neurotoxin (EDN), were assessed in the culture supernatant and in EoL-1 cells. We observed that, in a VitD deficient environment, EoL-1 cells produced high levels of the Eo-mediators, including MBP, EPX, ECP and EDN, which could be suppressed by the addition of calcitriol to the culture. EoL-1 cells expressed VitD receptor (VDR), which was up regulated by exposure to calcitriol. VDR formed complexes with the transcription factors of the Eo-mediators, which prevented the transcription factors to bind to the promoters of the Eo-mediators, and therefore prevented the Eo-mediated gene transcription. The Eo spontaneous activation was also found in the intestinal mucosa of VDR-deficient mice, in which the intestinal epithelial barrier dysfunction was observed. In conclusion, VDR contributes to the maintenance of the homeostasis of Eos by regulating the gene transcription of the Eo mediators. The VDR-deficiency is one of the causative factors inducing Eo spontaneous activation. This phenomenon may be taken into account in the management of the Eo-related diseases.

Advances and highlights in allergen immunotherapy: On the way to sustained clinical and immunologic tolerance

Allergen immunotherapy (AIT) is an effective treatment strategy for allergic diseases and has been used for more than 100 years. In recent years, however, the expectations on concepts, conduct, statistical evaluation, and reporting have developed significantly. Products have undergone dose-response and confirmative studies in adults and children to provide evidence for the optimal dosage, safety, and efficacy of AIT vaccines using subcutaneous and sublingual delivery pathways in large patient cohorts, ensuring solid conclusions to be drawn from them for the advantage of patients and societies alike. Those standards should be followed today, and products answering to them should be preferred over others lacking optimization and proof of efficacy and safety. Molecular and cellular mechanisms of AIT include early mast cell and basophil desensitization effects, regulation of T- and B-cell responses, regulation of IgE and IgG₄ production, and inhibition of responses from eosinophils, mast cells, and basophils in the affected tissues. There were many developments to improve vaccination strategies, demonstration of new molecules involved in molecular mechanisms, and demonstration of new biomarkers for AIT during the last few years. The combination of probiotics, vitamins, and biological agents with AIT is highlighting current advances. Development of allergoids and recombinant and hypoallergenic vaccines to skew the immune response from IgE to IgG₄ and regulation of dendritic cell, mast cell, basophil, innate lymphoid cell, T-cell, and B-cell responses to allergens are also discussed in detail.

Emerging Approaches to Food Desensitization in Children

PURPOSE OF REVIEW

The purpose of this review is to highlight the recent advances in food desensitization in children with food allergy.

RECENT FINDINGS

Recent advancements in epicutaneous, sublingual, and oral immunotherapy for food allergy in the future may offer children with food allergy and their families a viable option to reduce risk or severity of anaphylaxis with phase III trials ongoing for two of these treatment modalities. Food allergy prevalence in children is estimated to be up to 8%. These children are at risk of significant allergic reactions and anaphylaxis. Food avoidance and use of antihistamines or epinephrine has been the standard of care for these patients. This approach also has a significant socioeconomic effects on patients and their families. Recent advancements in understanding food allergy have allowed for exploring new methods of treatment. There is an increasing interest in oral immunotherapy, epicutaneous immunotherapy, or sublingual immunotherapy for food allergy. There have been also innovative approaches to immunotherapy by modification of food allergens (to make them less allergenic while maintain their immunogenicity) or adding adjunctive treatments (probiotics, anti-IgE, etc.) to increase efficacy or safety.

Diagnosing allergic sensitizations in the third millennium: why clinicians should know allergen molecule structures

Diagnostic tests to detect allergic sensitization were introduced at the end of the nineteenth century but only in the late 1990s did the advent of molecular allergology revolutionize the approach to the allergic patient. Personalized Medicine, a medical procedure that separates patients into different groups with different medical decisions, practices and interventions has sanctioned this change. In fact, in the last few years molecular allergology and the observation that not every patient has the same allergic profile, even when allergic to the same allergenic source, has originated the concept "one size does not fit all". This new approach requires the identification of still unknown allergens, but also the more detailed investigation of those already known. In depth studies of the structure-function relationships in allergenic molecules can reveal the structural determinants involved in the IgE-binding. Then, the knowledge of the epitope profile of each allergen and of the environmental/experimental conditions affecting the exposure of IgE-binding epitopes can provide important contributions to the understanding of cross-reaction processes and to the improvement of diagnosis, immunotherapy and the overall patient treatment. The evolution of diagnostic systems cannot ignore these new needs in this field.

Targeting the T Helper 2 Inflammatory Axis in Atopic Dermatitis

Atopic dermatitis (AD) is a chronic inflammatory skin disease that affects up to 25% of children and 10% of adults. The skin of patients with moderate to severe AD is characterized by significant barrier disruption and T helper 2 (Th2)-driven inflammation, which are thought to play a significant role in the pathogenesis of AD. Current management of AD is aimed at suppressing the inflammatory response and restoring the barrier function of the skin, reducing exacerbations, and preventing secondary skin infections. Combinations of treatment strategies are used to alleviate the symptoms of the disease; however, resolution is often temporary, and long-term usage of some of the medications for AD can be associated with significant side effects. Antibody therapies previously approved for other inflammatory diseases have been evaluated in patients with AD. Unfortunately, they have often failed to result in significant clinical improvement. Monoclonal antibodies and novel small molecules currently in development may provide more consistent benefit to patients with AD by specifically targeting the immune and molecular pathways important for the pathogenesis of AD. Here we review the state-of-the-art therapeutics targeting the Th2 axis in AD.