Initiating mechanisms of food allergy: Oral tolerance versus allergic sensitization

Kiwifruit's Allergy in Children: What Do We Know?

Kiwifruit allergy is an emerging pathological condition in both general and pediatric populations with a wide range of symptoms linked to variable molecular patterns, justifying systemic and cross-reactions with other allergens (i.e., latex, pollen, and fruit). Skin prick test (SPT), specific serum IgE (Act d 1, Act d 2, Act d 5, Act d 8, and Act d 10) directed against five out of thirteen molecular allergens described in the literature, and oral test challenge with kiwifruit are available for defining diagnosis. The management is similar to that of other food allergies, mostly based on an elimination diet. Although kiwi allergy has been on the rise in recent years, few studies have evaluated the clinical characteristics and methods of investigating this form of allergy. Data collected so far show severe allergic reaction to be more frequent in children compared to adults. Therefore, the aim of this review is to collect the reported clinical features and the available association with specific molecular patterns of recognition to better understand how to manage these patients and improve daily clinical practice.

Route of Sensitization to Peanut Influences Immune Cell Recruitment at Various Mucosal Sites in Mouse: An Integrative Analysis

Symptom occurrence at the first ingestion suggests that food allergy may result from earlier sensitization via non-oral routes. We aimed to characterize the cellular populations recruited at various mucosal and immune sites after experimental sensitization though different routes. BALB/cJ mice were exposed to a major allergenic food (peanut) mixed with cholera toxin via the intra-gastric (i.g.), respiratory, cutaneous, or intra-peritoneal (i.p.) route. We assessed sensitization and elicitation of the allergic reaction and frequencies of T cells, innate lymphoid cells (ILC), and inflammatory and dendritic cells (DC) in broncho-alveolar lavages (BAL), lungs, skin, intestine, and various lymph nodes. All cellular data were analyzed through non-supervised and supervised uni/multivariate analysis. All exposure routes, except cutaneous, induced sensitization, but intestinal allergy was induced only in i.g.- and i.p.-exposed mice. Multivariate analysis of all cellular constituents did not discriminate i.g. from control mice. Conversely, respiratory-sensitized mice constituted a distinct cluster, characterized by high local inflammation and immune cells recruitment. Those mice also evidenced changes in ILC frequencies at distant site (intestine). Despite absence of sensitization, cutaneous-exposed mice evidenced comparable changes, albeit less intense. Our study highlights that the initial route of sensitization to a food allergen influences the nature of the immune responses at various mucosal sites. Interconnections of mucosal immune systems may participate in the complexity of clinical manifestations as well as in the atopic march.

Characterization of the molecular properties and allergenicity (IgE-binding capacity) of β-lactoglobulin by heat treatment using asymmetric-flow field-flow fractionation and ultra-performance liquid chromatography quadrupole time of flight mass chromatography

In this study, the heat product (90 °C, 10 min) of β-lactoglobulin (β-LG) was analyzed by asymmetric-flow field-flow fractionation (AF4) to observe the effect of heat treatment. The changes in molar mass (M) and molar size induced by heat treatment were characterized by AF4, and changes in molar shape were observed by transmission electron microscopy (TEM). The results showed that β-LG dissociated and aggregated into four fractions with different M values, sizes, and shapes after heat treatment. The vast aggregations with the highest allergenicity (IgE-binding capacity) might enhance the allergenicity of β-LG. However, the number of characterized epitope peptides was decreased due to heat treatment. The above results provide some references for related studies of β-LG and its allergenicity. Further separation and characterization of the high-allergenicity fractions and peptides will help to eliminate allergens in dairy products and reduce the occurrence of allergic reactions.

Comparison of allergenicity among cow, goat, and horse milks using a murine model of atopy

Due to the prevalence and severity of cow milk (CM) allergy (CMA), an ideal substitute is urgently needed to develop hypoallergenic infant formula for infants who experience anaphylaxis to typical whey-based CM formula. Goat milk (GM) and horse milk (HM) are considered appropriate substitutes; however, whether GM and HM are less allergenic than CM is unclear. In the present study, the difference in allergenicity among CM, GM, and HM was investigated using the Balb/c mouse model. The number of mice with severe respiratory symptoms was significantly lower in the GM- and HM-sensitised groups than in the CM-sensitised group. Furthermore, histologic examination of intestinal and lung tissues revealed a thinner lamina propria of the small intestine and obvious inflammation and congestion in lungs in the CM-sensitised group than in the GM- and HM-sensitised groups. CM-specific immunoglobulin (Ig) E, serum IgG1, and plasma histamine levels were also higher in CM-sensitised mice than in GM- or HM-sensitised mice. In addition, higher interleukin (IL) 4 and IL-17A levels and lower interferon-γ (IFN-γ) and IL-10 levels were observed in CM-sensitised mice compared with GM- and HM-sensitised mice, according to qPCR, indicating Th1/Th2 and Treg/Th17 imbalances. The CM-sensitised group had a higher proportion of IL-4- and IL-17A-producing CD3+ T cells but a lower proportion of IFN-γ- and IL-10-producing CD3+ T cells compared with the GM- and HM-sensitised groups, confirming the Th1/Th2 and Treg/Th17 imbalances. In conclusion, GM and HM were less allergenic than CM in mice as a result of a shift in the Th1/Th2 and Treg/Th17 imbalances; however, HM was less allergenic than GM and can be used as an alternative milk to develop infant formulas for children with CMA.

Allergic symptoms and sensitisation in adolescents with cows' milk allergy and atopic eczema in infancy

Background

The association between atopic sensitisation, atopic eczema (AE) and asthma is known, but distinct roles of allergies on long‐term health are unestablished.

Objective

Evaluation of allergic symptoms and sensitisation in adolescents who in infancy had AE and verified cows' milk allergy (CMA) or AE and a negative CMA challenge, and controls.

Methods

Children with AE, with and without CMA, from a randomised controlled study in 1999‐2001 examining the effect of probiotics on AE severity at older than 12 months of age, attended a follow‐up visit at age 16 to 18, with age‐matched controls. Data came from a questionnaire (ISAAC questionnaire), analysis of serum antigen‐specific immunoglobulin Es (IgEs), and clinical evaluation. Group comparisons were carried out (χ² tests and logistic regression).

Results

Fifty‐two patients with AE and CMA (AE/CMA+ group), 52 with AE and suspicion of CMA (AE/CMA− group), and 57 controls attended a study visit. IgE‐mediated sensitisation was significantly more prevalent in the AE/CMA+ group vs the controls, for horse, cat, dog, egg white and wheat (P < .024 for all). For birch, timothy and mugwort (P < .008 for all), sensitisation was more prevalent in both the AE/CMA+ group and the AE/CMA− group vs controls. On the basis of questionnaire data the AE/CMA + group reported a significantly higher lifetime prevalence of wheezing (64% vs 35% and 32%; P = .001), noninfectious rhinitis (85% vs 62% and 56%; P = .004), and hay fever (77% vs 52% and 33%; P < .001) vs the AE/CMA− group and the control group, respectively.

Conclusion and Clinical Relevance

Patients with AE and CMA in infancy, as opposed to patients with AE only, or controls, report more allergic symptoms and exhibit more allergic sensitisation in adolescence. This indicates that CMA in infancy is an independent risk factor of allergic disease in adolescence.

Hypoallergenic Proteins for the Treatment of Food Allergy

PURPOSE OF REVIEW

Food allergy is a growing health problem worldwide that impacts millions of individuals. Current treatment options are limited and strict dietary avoidance remains the standard of care. Immunotherapy using whole, native allergens is under active clinical investigation but harbors the risk of severe side effects including anaphylaxis. Newer food-specific therapies with hypoallergenic proteins may potentially offer safer treatment alternatives, and this review seeks to investigate the evidence supporting the use of these modalities.

RECENT FINDINGS

The utilization of different methods to alter allergen structure and IgE binding leads to reduced allergenicity and decreases the risk for systemic reactions, making the use of potential therapies including extensively heated egg/milk, peptide immunotherapy, recombinant allergen immunotherapy, and DNA vaccines safe and possibly efficacious forms of treatment in food allergy. However, for the majority of these treatment modalities, limited data currently exists looking at the safety and efficacy in human subjects with food allergy. This review provides a comprehensive overview of the current evidence examining the safety and efficacy of hypoallergenic proteins in the treatment of food allergies.

Micro RNA-19a interferes with IL-10 expression in peripheral dendritic cells of patients with nasal polyposis

The pathogenesis of nasal polyp is to be further investigated. Micro RNA (miR) plays a role in the development of allergic inflammation. Interleukin (IL)-10-producing dendritic cells (DC) have immune tolerogenic properties. This study test a hypothesis that miR-17-92 cluster is associated with suppressing IL-10 in peripheral DC. In this study, peripheral blood samples were obtained from 26 patients with nasal polyp. The CD11c DCs were isolated from the blood samples and analyzed for the expression of IL-10. We observed that, as compared with healthy subjects, the IL-10 expression in peripheral DC was significantly lower in polyp patients. The levels of miR-19a, but not the rest 5 members of the miR-17-92 cluster, were markedly higher in DCs in polyp group. Exposure to recombinant IL-4 suppressed the IL-10 expression in DCs, which was abolished by blocking histone deacetylase-11 or knocking down the miR-19a gene in DCs. We conclude that miR-19a plays a critical role in the suppression of IL-10 in peripheral DCs, which may be a target in the immune therapy for nasal polyp.

Effect of a cocoa diet on the small intestine and gut-associated lymphoid tissue composition in an oral sensitization model in rats

Previous studies have attributed to the cocoa powder the capacity to attenuate the immune response in a rat oral sensitization model. To gain a better understanding of cocoa-induced mechanisms at small intestinal level, 3-week-old female Lewis rats were fed either a standard diet or a diet containing 10% cocoa for 4 weeks with or without concomitant oral sensitization with ovalbumin (OVA). Thereafter, we evaluated the lymphocyte composition of the Peyer's patches (PPL), small intestine epithelium (IEL) and lamina propria (LPL). Likewise, gene expression of several immune molecules was quantified in the small intestine. Moreover, histological samples were used to evaluate the proportion of goblet cells, IgA+ cells and granzyme+cells as well. In cocoa-fed animals, we identified a five-time reduction in the percentage of IgA+ cells in intestinal tissue together with a decreased proportion of TLR4+ IEL. Analyzing the lymphocyte composition, almost a double proportion of TCRγδ+cells and an increase of NK cell percentage in PPL and IEL were found. In addition, a rise in CD25+, CD103+ and CD62L- cell proportions was observed in CD4+ PPL from cocoa-fed animals, along with a decrease in gene expression of CD11b, CD11c and IL-10. These results suggest that changes in PPL and IEL composition and in the gene expression induced by the cocoa diet could be involved, among other mechanisms, on its tolerogenic effect.

New pharmaceutical approaches for the treatment of food allergies

INTRODUCTION

Allergic diseases constitute one of the most common causes of chronic illness in developed countries. The main mechanism determining allergy is an imbalance between Th1 and Th2 response towards Th2.

AREAS COVERED

This review describes the mechanisms underlying the natural tolerance to food components and the development of an allergic response in sensitized individuals. Furthermore, therapeutic approaches proposed to manage these abnormal immunologic responses food are also presented and discussed.

EXPERT OPINION

In the past, management of food allergies has consisted of the education of patients to avoid the ingestion of the culprit food and to initiate the therapy (e.g. self-injectable epinephrine) in case of accidental ingestion. In recent years, sublingual/oral immunotherapies based on the continuous administration of small amounts of the allergen have been developed. However, the long periods of time needed to obtain significant desensitization and the generation of adverse effects, limit their use. In order to solve these drawbacks, strategies to induce tolerance are being studied, such as the use of either adjuvant immunotherapy in order to facilitate the reversion of the Th2 response towards Th1 or the use of monoclonal antibodies to block the main immunogenic elements.

Lactobacillus rhamnosus induced epithelial cell apoptosis, ameliorates inflammation and prevents colon cancer development in an animal model

BACKGROUND/AIM

Probiotics have been suggested as prophylactic measure in colon carcinogenesis. This study aimed at determining the potential prophylactic activity of Lactobacillus rhamnosus GG CGMCC 1.2134 (LGG) strain on colorectal carcinogenesis via measuring its effect on Nuclear factor kappa B (NFκB) inflammatory pathway and apoptosis.

MATERIALS AND METHODS

64 Sprague Dawley rats were grouped into four as follows; Group 1 (Healthy control), Group 2 (LGG), Group 3 (cancer control Dimethyl hydrazine (DMH)) and Group 4 (LGG+DMH). LGG was administered orally to LGG and LGG+DMH groups. Colon carcinogenesis was chemically induced in LGG+DMH and DMH groups by weekly injection of 40mg/kg DMH. Animals were sacrificed after 25 weeks of experiment and tumor characteristics assessed. The change in expression of NFκB-p65, COX-2, TNFα, Bcl-2, Bax, iNOS, VEGFα, β-catenin, Casp3 and p53 were evaluated by western blotting and qRT-PCR.

RESULTS

LGG treatment significantly reduced tumor incidence, multiplicity and volume in LGG+DMH treatment group compared to DMH cancer control group. Also, LGG treatment reduced the expression of β-catenin and the inflammatory proteins NFκB-p65, COX-2 and TNFα; the anti-apoptotic protein Bcl-2, but increased the expression of the pro-apoptotic proteins Bax, casp3 and p53 compared with DMH group.

CONCLUSION

LGG have a potential protection effect against colon carcinogenesis; inducing apoptosis and ameliorating inflammation, and may hold a promise as bio-therapeutic dietary agent.

Immunomodulating properties of protein hydrolysates for application in cow's milk allergy

Cow's milk proteins cause allergic symptoms in 2-3% of all infants. In these individuals, the tolerogenic state of the intestinal immune system is broken, which can lead to sensitization against antigens and eventually to allergic responses. Although a true treatment for food allergy is not available, symptoms can be avoided by providing the infants with hydrolyzed proteins. Hydrolyzed proteins are proteins that are enzymatically degraded. They lack typical allergenic IgE-binding epitopes but are also thought to play a pertinent role in other mechanisms inducing hypoallergenic effects. This review discusses the mechanisms and evidence for immunomodulating properties of cow's milk hydrolysates. Hydrolysates are found to strengthen the epithelial barrier, modulate T-cell differentiation, and decrease inflammation. Some studies suggest a role for hydrolysates in manipulating pathogen recognition receptors signaling as underlying mechanism. Peptides from hydrolysates have been shown to bind to TLR2 and TLR4 and influence cytokine production in epithelial cells and macrophages. Current insight suggests that hydrolysates may actively participate in modulating the immune responses in subjects with cow's milk allergy and those at risk to develop cow's milk allergy. However, more research is required to design effective and reproducible means to develop targeting strategies to modulate the immune response.

Immunosuppression in early postnatal days induces persistent and allergen-specific immune tolerance to asthma in adult mice

Bronchial asthma is a chronic airway inflammatory condition with high morbidity, and effective treatments for asthma are limited. Allergen-specific immunotherapy can only induce peripheral immune tolerance and is not sustainable. Exploring new therapeutic strategies is of great clinical importance. Recombinant adenovirus (rAdV) was used as a vector to make cells expressing cytotoxic T lymphocyte-associated antigen-4-immunoglobulin (CTLA4Ig) a soluble CTLA4 immunoglobulin fusion protein. Dendritic cells (DCs) were modified using the rAdVs together with allergens. Then these modified DCs were transplanted to mice before allergen sensitization. The persistence and specificity of immune tolerance were evaluated in mice challenged with asthma allergens at 3 and 7 months. DCs modified by CTLA4Ig showed increased IL-10 secretion, decreased IL-12 secretion, and T cell stimulation in vitro. Mice treated with these DCs in the early neonatal period developed tolerance against the allergens that were used to induce asthma in the adult stage. Asthma symptoms, lung damage, airway reactivity, and inflammatory response all improved. Humoral immunity indices showed that this therapeutic strategy strongly suppressed mice immune responses and was maintained for as long as 7 months. Furthermore, allergen cross-sensitization and challenge experiments demonstrated that this immune tolerance was allergen-specific. Treatment with CTLA4Ig modified DCs in the early neonatal period, inducing persistent and allergen-specific immune tolerance to asthma in adult mice. Our results suggest that it may be possible to develop a vaccine for asthma.

Effect of a protein-free diet in the development of food allergy and oral tolerance in BALB/c mice

The aim of the present study was to investigate the effect of a protein-free diet in the induction of food allergy and oral tolerance in BALB/c mice. The experimental model used was mice that were fed, since weaning up to adulthood, a balanced diet in which all dietary proteins were replaced by amino acid diet (Aa). The absence of dietary proteins did not prevent the development of food allergy to ovalbumin (OVA) in these mice. However, Aa-fed mice produced lower levels of IgE, secretory IgA and cytokines. In addition, when compared with mice from control group, Aa-fed mice had a milder aversive reaction to the allergen measured by consumption of OVA-containing solution and weight loss during food allergy development. In addition, mice that did not have dietary proteins in their diets were less susceptible to induction of oral tolerance. One single oral administration was not enough to suppress specific serum Ig and IgG1 levels in the Aa-fed group, although it was efficient to induce suppression in the control group. The present results indicate that the stimulation by dietary proteins alters both inflammatory reactivity and regulatory immune reactivity in mice probably due to their effect in the maturation of the immune system.

Immunotherapy - risk/benefit in food allergy

Food allergy is a growing health concern in the westernized world with approx. 6% of children suffering from it. A lack of approved treatment has led to strict avoidance of the culprit food proteins being the only standard of care. Nowadays in-depth research is conducted to evaluate the possible use of allergen-specific immunotherapy (SIT) as an active therapeutic option for food allergy. Various routes of administration for the immunotherapy are investigated, including subcutaneous, oral, sublingual, and epicutaneous, and some appear to be successful in inducing a temporary tolerant state. Most research has been conducted with oral immunotherapy due to its efficacious and relatively safe profile. Increasing interest is dedicated to safer and more convenient approaches, such as sublingual and epicutaneous SIT; however, doubts exist about their possible capacity to induce temporary tolerant state and permanent oral tolerance. The high frequency of allergic adverse reactions of the various approaches and the inability to achieve permanent oral tolerance have highlighted the need of refinements in the strategies. A promising strategy for preventing IgE cross-linking and thus enhancing safety of SIT, while still activating T cells, is the use of tolerogenic peptides. The implementation of such an immunotherapy approach has the potential of not only increasing the chance of achieving a permanent state of tolerance, but also improving the safety and tolerability of the therapy. Immunotherapy for food allergy is still not ready for the clinic, but current and upcoming studies are dedicated to collect enough evidence for the possible implementation of allergen-SIT as a standard treatment for food allergy.

Identification and characterization of cow's milk proteins from the rat intestinal lymph using a proteomic strategy

Food proteins were considered to be absorbed into the body after being digested to amino acids, dipeptides, and tripeptides. However, there are studies indicating that some proteins can pass through the intestinal epithelium under normal physiological conditions, perhaps not in sufficient quantities to be of nutritional importance, but in quantities that may be antigenically or biologically active. In the present study, rat intestinal lymph samples were collected using a modified lymph fistula rat model in fasting and cow's milk postprandial states. Low molecular weight proteins were enriched by ultrafiltration and differential solubilization, separated by 1D-SDS-PAGE, digested in-gel based on molecular weight, and identified using nano-LC-MS/MS. In the postprandial rat intestinal lymph, nine bovine-specific proteins (false discovery rate ≤1%) were identified in different molecular weight regions. Most proteins identified in lymph were highly abundant proteins in the milk, such as β-lactoglobulin and caseins. Seven of the nine identified bovine-specific proteins are allergens in milk. This strategy can be used to search for proteins that can enter the intestinal lymph and analyze their common features. Understanding the common features of these proteins might help to develop protein drugs taken orally, so that therapeutic proteins might embody fusion domains for cross-barrier transport or translocation.

Prevention of oral food allergy sensitization via skin application of food allergen in a mouse model

BACKGROUND

Treatment options for food allergy remain limited. Development of novel approaches for the prevention and/or treatment of severe peanut allergy and other food allergies is urgently needed. The objective of this study was to test whether skin application of food allergen can be used as a prophylactic and/or therapeutic intervention for food allergy.

METHODS

Balb/C mice were given 5 weekly cutaneous application of complete peanut extract (CPE) or ovalbumin (OVA) ranging from 10 to 1000 μg on the shaved back skin, followed by 5 weekly treatments with oral CPE or OVA plus cholera toxin to induce allergic reactivity to the food. At various time points, the immunologic responses and allergic clinical manifestations to allergens were examined.

RESULTS

Skin application of a 10-1000 μg dose of CPE or OVA to structurally intact skin did not lead to allergic sensitization to peanut or OVA. Rather, cutaneous allergen application blocked, in a dose-dependent fashion, the subsequent induction of the oral sensitization including inhibiting oral sensitization-induced CPE-specific IgE, IgG1, and IgG2a production, suppressing the peanut anaphylaxis, and modulating the oral sensitization-promoted cytokine production. The cutaneous OVA application also resulted in similar results as seen with CPE application.

CONCLUSION

Cutaneous application of intact skin with peanut or OVA can block the development of orally induced corresponding food allergies, suggesting that allergic tolerance to peanuts and OVA might be achieved via allergen cutaneous application.

Host-microbial interactions and regulation of intestinal epithelial barrier function: From physiology to pathology

The gastrointestinal tract is the largest reservoir of commensal bacteria in the human body, providing nutrients and space for the survival of microbes while concurrently operating mucosal barriers to confine the microbial population. The epithelial cells linked by tight junctions not only physically separate the microbiota from the lamina propria, but also secrete proinflammatory cytokines and reactive oxygen species in response to pathogen invasion and metabolic stress and serve as a sentinel to the underlying immune cells. Accumulating evidence indicates that commensal bacteria are involved in various physiological functions in the gut and microbial imbalances (dysbiosis) may cause pathology. Commensal bacteria are involved in the regulation of intestinal epithelial cell turnover, promotion of epithelial restitution and reorganization of tight junctions, all of which are pivotal for fortifying barrier function. Recent studies indicate that aberrant bacterial lipopolysaccharide-mediated signaling in gut mucosa may be involved in the pathogenesis of chronic inflammation and carcinogenesis. Our perception of enteric commensals has now changed from one of opportunistic pathogens to active participants in maintaining intestinal homeostasis. This review attempts to explain the dynamic interaction between the intestinal epithelium and commensal bacteria in disease and health status.

Vitamin D and allergic disease: sunlight at the end of the tunnel?

A role for vitamin D in the regulation of immune function was first proposed after the identification of Vitamin D receptors in lymphocytes. It has since been recognized that the active form of vitamin D, 1α,25(OH)₂D₃, has direct affects on naïve and activated helper T cells, regulatory T cells, activated B cells and dendritic cells. There is a growing body of literature linking vitamin D (serum 25(OH)D, oral intake and surrogate indicators such as latitude) to various immune-related conditions, including allergy, although the nature of this relationship is still unclear. This review explores the findings of epidemiological, clinical and laboratory research, and the potential role of vitamin D in promoting the inappropriate immune responses which underpin the rise in a broad range of immune diseases.

Sensitization with 7S globulins from peanut, hazelnut, soy or pea induces IgE with different biological activities which are modified by soy tolerance

BACKGROUND

It is not known why some foods sensitizing via the gastrointestinal tract are prevalent allergenic foods and others are not. Eating habits, processing, and the food matrix have been suggested to influence the allergenicity of a given food. Factors related to protein structure, such as stability to digestion, have also been suggested. 7S globulins from peanut, hazelnut, soy, and pea were studied to determine whether related proteins would induce a similar sensitization when removed from their 'normal' matrix.

METHODS

Brown Norway rats (soy tolerant or nontolerant) were immunized i.p. 3 times with 100 μg purified peanut, hazelnut, soy, or pea 7S without adjuvant. Sera were analyzed for specific antibodies by different ELISAs (IgG1, IgG2a, and IgE), inhibition ELISA, and rat basophilic leukemia cell assay.

RESULTS

The 4 related 7S globulins induced a response with an almost identical level of specific antibodies, but peanut 7S induced IgE of higher avidity than hazelnut and pea 7S which, again, had a higher avidity than IgE induced by soy 7S. Soy tolerance reduced the functionality of IgE without influencing antibody titers.

CONCLUSIONS

Although the 4 7S globulins are structurally related allergens, they induce antibodies with different antigen-binding characteristics. Peanut 7S induces IgE of a higher avidity than hazelnut and pea 7S which, again, has a higher avidity than IgE induced by soy 7S. We also show that soy tolerance influences the function of antibodies to peanut 7S. These findings may help explain how antibodies of different clinical significances can develop in different individuals sensitized to the same allergen.

In vitro model for IgE mediated food allergy

BACKGROUND

In intestinal food allergy, the non-specificity of gastrointestinal symptoms and the limited access to the reacting organ are the reasons for the limited understanding of the pathophysiology of this disease and the difficulties in establishing an appropriate diagnosis in the individual patient.

OBJECTIVE

To develop an in vitro model reproducing pathophysiological mechanisms of IgE mediated food allergy.

METHODS

Distal duodenum biopsies of nine patients with food allergy and 10 control subjects were cultured for 3 h with medium alone and with 1 mg/ml of peptic-tryptic digest of wheat gliadin, wheat albumins, and apple proteins. Each biopsy was used for conventional histological examination and for immunohistochemical detection of IgE-positive cells. We have also analyzed the expression of tight junction proteins, occludin, claudin-1, and ZO-1 by immunoconfocal microscopy. Histamine and tryptase release were measured in the culture medium and collected at 0, 30 min, and 3 h of culture using an enzyme and radio immunoassay, respectively.

RESULTS

Exposure of small intestinal biopsy specimens of patients with food allergy to food allergens led to a significative increase of IgE-positive cells with a significative increase of histamine and tryptase release and an altered expression of tight junction proteins. No differences were found in intestinal biopsies of controls, cultured with or without food antigens.

CONCLUSIONS

Small intestinal organ culture is a functional model of food allergy and could be considered as an in vitro oral food challenge, with evident reduction of costs and risks for the patients.

Lipoic acid: an immunomodulator that attenuates glycinin-induced anaphylactic reactions in a rat model

The purpose of this study was to evaluate the attenuation effects of consuming a small dose of lipoic acid on soybean glycinin-induced hypersensitivity using a rat model. Sensitized by gavage with glycinin, weaned rats were orally supplemented with the diet containing 12.5 mug of lipoic acid/g (per diet). Results showed that untreated, sensitized rats demonstrated an increase in the level of serum IgE, the level of histamine release, and incidence of diarrhea and reduced growth performance compared with the controls (P < 0.05). Lipoic acid significantly (P < 0.05) improved growth performance while reducing mast cell numbers, the level of serum IgE, and the level of histamine release. Lipoic acid supplementation altered the balance of cytokines, attenuated the Th2-type immune response, and amended the ratio of CD4(+) to CD8(+) T cells (P < 0.05). Our results suggest that a small dose of lipoic acid has the potential to be an immunomodulator to prevent soybean-induced allergies.

Allergen-specific antibody and cytokine responses, mast cell reactivity and intestinal permeability upon oral challenge of sensitized and tolerized mice

BACKGROUND

Food allergy has reached an epidemic level in westernized countries and although central mechanisms have been described, the variability associated with genetic diversity underscores the still unresolved complexity of these disorders.

OBJECTIVE

To develop models of food allergy and oral tolerance, both strictly induced by the intestinal route, and to compare antigen-specific responses.

METHODS

BALB/c mice were mucosally sensitized to ovalbumin (OVA) in the presence of the mucosal adjuvant cholera toxin, or tolerized by intra-gastric administrations of OVA alone. Antibody titres and cytokines were determined by ELISA, and allergic status was determined through several physiologic parameters including decline in temperature, diarrhoea, mast cell degranulation and intestinal permeability.

RESULTS

OVA-specific antibodies (IgE, IgGs and IgA in serum and feces) were produced in sensitized mice exclusively. Upon intra-gastric challenge with OVA, sensitized mice developed anaphylactic reactions associated with a decline of temperature, diarrhoea, degranulation of mast cells, which were only moderately recruited in the small intestine, and increased intestinal permeability. Cytokines produced by immune cells from sensitized mice included T-helper type 2 cytokines (IL-5, IL-13), but also IL-10, IFN-gamma and IL-17. In contrast, all markers of allergy were totally absent in tolerized animals, and yet the latter were protected from subsequent sensitization, demonstrating that oral tolerance took place efficiently.

CONCLUSION

This work allows for the first time an appropriate comparison between sensitized and tolerized BALB/c mice towards OVA. It highlights important differences from other models of allergy, and thus questions some of the generally accepted notions of allergic reactions, such as the protective role of IFN-gamma, the importance of antigen-specific secretory IgA and the role of mucosal mast cells in intestinal anaphylaxis. In addition, it suggests that IL-17 might be an effector cytokine in food allergy. Finally, it demonstrates that intestinal permeability towards the allergen is increased during challenge.

Atopic dermatitis and allergic reactions to individual fragrance chemicals

BACKGROUND

Allergic contact dermatitis prevalence is reported as equal in atopic and nonatopic dermatitis. Atopic dermatitis is under-represented in those with allergic contact dermatitis to agents having cutaneous and dietary exposure. We compared rates of atopic dermatitis between patients with allergic contact dermatitis arising out of individual fragrance chemicals with known oral/cutaneous exposure against exclusively cutaneous exposure.

METHODS

Between 1982 and 2007, 37 065 dermatitis patients were tested with Fragrance mix I. Those who were positive were tested for individual fragrance allergy. Chemicals were categorized according to whether their exposure pattern was solely cutaneous, oral or mixed. Current and past atopic dermatitis rates were compared between the whole population and groups allergic to individual fragrances. Age and gender were controlled.

RESULTS

Cinnamic alcohol and cinnamal allergy groups had reduced rates of both 'current' [24/266 (9.0%) P = 0.0008, 38/364 (10.4%) P = 0.0005] and 'past' atopic dermatitis [44/266 (16.5%) P = 0.009, 70/346 (19.2%) P = 0.037]. Atopic dermatitis rates in groups allergic to Evernia prunastri and hydroxycitronellal (cutaneous exposure only) were not reduced [120/597 (20.1%) and 41/153 (26.8%)]. Groups allergic to cinnamic alcohol (P < 0.0001, P < 0.0001) and cinnamal (P < 0.0001, P < 0.004) had reductions in 'current' and 'past' atopic dermatitis, compared with Evernia prunastri.

CONCLUSIONS

Patients allergic to individual fragrances with dietary exposure have reduced rates of atopic dermatitis. This suggests that patients with atopic dermatitis have heightened oral tolerance to dietary haptens, in contrast to the known close association of atopic dermatitis with food-protein allergy. Haptens may interfere with food protein tolerance by binding to soluble protein to alter its configuration and immunogenic profile.

Does hapten exposure predispose to atopic disease? The hapten-atopy hypothesis

Contact allergy data indicates that atopics have heightened oral tolerance to haptens (chemical allergens). We speculate here, that artificially increased oral exposure to chemicals compete with dietary proteins for the development of oral tolerance, predisposing to the acquisition of food protein allergy and representing one driver for the increasing prevalence of protein allergy and/or atopy. Hapten exposure via other surfaces such as the skin and airways might also be important in promoting atopic disease. Consistent with this hypothesis it is notable that over 40 years, with the huge increase in atopic disease, there has also been an increase in dietary hapten exposure through processed food, formula milk and oral antibiotic and drug use.

Effects of soybean glycinin on performance and immune function in early weaned pigs

Glycinin, a major storage protein in soybean, has been identified as an important food allergen. The present study was conducted to investigate the effects of soybean glycinin on the local and systemic immune responses using a swine model specific for glycinin allergy. Performance, peripheral blood lymphocyte proliferation and CD4+ and CD8+ subsets in the plasma of naive and sensitised piglets were determined. In addition, the concentrations of IgA, IgG, IgM, interleukin-4 and interleukin-6 in the jejunum mucosa were measured. Our results showed that dietary supplementation of glycinin reduced piglet performance (p < 0.05), while increasing lymphocyte proliferation and CD4+/ CD8+ ratio (p < 0.01). Intestinal mucosal immune responses to glycinin were enhanced with high levels of IgA (p < 0.01) as well as interleukin-4 and interleukin-6 in the jejunum mucosa in glycinin-treated piglets compared with the control (p < 0.01). There were no differences due to treatment in the densities of IgG and IgM. In conclusion, it was found that glycinin stimulated local and systemic immune responses in allergic piglets and had negative effects on piglet performance. The severity of the immune reactions depends on the dose of glycinin with higher doses causing more severe symptoms.

Recent advances in the understanding of egg allergens: basic, industrial, and clinical perspectives

The emergence of egg allergy has had both industrial and clinical implications. In industrialized countries, egg allergy accounts for one of the most prevalent food hypersensitivities, especially in children. Atopic dermatitis represents the most common clinical manifestation in infancy; however, the range of clinical signs is broad and encompasses life-threatening anaphylaxis. The dominant egg allergens are proteins and are mainly present in the egg white, for example, ovalbumin, ovomucoid, ovotransferrin, and lysozyme. However, egg yolk also displays low-level allergenicity, for example, alpha-livetin. Strict avoidance of the offending food remains the most common recommendation for egg-allergic individuals. Nevertheless, the omnipresence of egg-derived components in prepackaged or prepared foods makes it difficult. Therefore, more efficient preventive approaches are investigated to protect consumers from inadvertent exposure and ensuing adverse reactions. On the one hand, commercial kits have become readily available that allow for the detection of egg contaminants at trace levels. On the other hand, attempts to produce hypoallergenic egg-containing products through food-processing techniques have met with promising results, but the approach is limited due to its potentially undesirable effects on the unique functional and sensory attributes of egg proteins. Therefore, the development of preventive or curative strategies for egg allergy remains strongly warranted. Pilot studies have suggested that oral immunotherapy (IT) with raw or cooked preparations of egg may represent a safe alternative, immediately available to allergic subjects, but remains applicable to only nonanaphylactic patients. Due to the limitations of conventional IT, novel forms of immunotherapy are sought based on information obtained from the molecular characterization of major egg allergens. In the past decade, promising approaches to the treatment and prevention of egg allergy have been explored and include, among others, the production of hypoallergenic recombinant egg proteins, the development of customized peptides, and bacterial-mediated immunotherapy. Nonspecific approaches have also been evaluated, and preliminary trials with the use of probiotic bacteria have yielded encouraging results. The current understanding of egg allergens offers novel approaches toward the making of food products safe for human consumption and the development of efficient immunotherapeutic strategies.

Age at first introduction of cow milk products and other food products in relation to infant atopic manifestations in the first 2 years of life: the KOALA Birth Cohort Study

OBJECTIVES

Scientific evidence is scarce about timing of solid-food introduction and its association with the development of atopy. We aimed to evaluate any associations between the introduction of cow milk products/other solid food products and infant atopic manifestations in the second year of life, taking into account reverse causation.

METHODS

Data from 2558 infants in an ongoing prospective birth cohort study in the Netherlands were analyzed. Data on the main determinants (introduction of cow milk products and other food products), outcomes (eczema; atopic dermatitis [United Kingdom Working Party criteria]; recurrent wheeze; any sensitization; sensitization against cow milk, hen egg, peanut, and at least 1 inhalant allergen), and confounders were collected by repeated questionnaires at 34 weeks of gestation and 3, 7, 12, and 24 months postpartum. Information on sensitization was gathered by venous blood collections performed during home visits at age 2. Analyses were performed by multiple logistic regression analyses.

RESULTS

More delay in introduction of cow milk products was associated with a higher risk for eczema. In addition, a delayed introduction of other food products was associated with an increased risk for atopy development at the age of 2 years. Exclusion of infants with early symptoms of eczema and recurrent wheeze (to avoid reverse causation) did not essentially change our results.

DISCUSSION

Delaying the introduction of cow milk or other food products may not be favorable in preventing the development of atopy.

Reduced frequency of atopic dermatitis in quinoline-allergic patients: the 'hapten-atopy hypothesis'

BACKGROUND

While allergy to food proteins is almost exclusively found in association with atopy, it has been our experience that contact allergy to some contact allergens/haptens with both cutaneous and gastrointestinal exposures is reduced in atopic dermatitis (AD) patients as a group.

OBJECTIVE

To assess the contact allergy rates of two classes of antimicrobial haptens, one with both cutaneous and gastrointestinal exposures (quinolines) and one with only significant cutaneous exposure (aminoglycosides), with respect to the presence or absence of AD.

METHODS

Contact allergy rates to neomycin (aminoglycoside) and quinoline mix/clioquinol in patients attending the St John's Institute of Dermatology for diagnostic patch testing were retrospectively analysed; current AD and history of AD were noted.

RESULTS

In comparison to neomycin-allergic subjects, there was a highly significant negative association between quinoline contact allergy and current presence of AD (P = 0.0028); negative association between quinoline contact allergy and a history of AD did not reach significance (P = 0.07).

CONCLUSIONS

In comparison to an antimicrobial with no significant gastrointestinal exposure (neomycin), contact allergy to quinolines is negatively associated with the presence of AD. This is in contrast to food protein allergy, which is strongly associated with atopy. Possible explanations could include (i) confounding factors or (ii) AD patients are efficient at orally tolerizing haptens and inefficient at orally tolerizing proteins, secondary to their atopic status or (iii) oral tolerance of haptens antagonizes tolerance of food proteins and also leads to an immunological shift towards atopy (hapten-atopy hypothesis).