Food allergy: an overview

Long-term characteristics of hazelnut allergy in an adjuvant-free mouse model

BACKGROUND

Clinically it is recognized that tree nut allergies such as hazelnut allergy are not usually outgrown. Specific mechanisms underlying the persistence of such food allergies are incompletely understood. Here we studied the natural history and the long-term immune and clinical characteristics of hazelnut allergy in an adjuvant-free mouse model.

METHODS

BALB/c mice were sensitized to hazelnut protein using a transdermal sensitization protocol that does not use adjuvant. After establishing sensitization, exposure to hazelnut was withdrawn for 3, 5 or 8 months. The fate of circulating IgE antibodies was monitored. Subsequently, mice were given booster exposures and examined for memory IgE antibody and spleen cell IL-4 responses. Clinical characteristics and hypothermia responses upon oral allergen challenge were studied.

RESULTS

Upon allergen withdrawal, circulating hazelnut-specific IgE antibody levels began to drop. Nevertheless, IgE responses once established remained at significantly high levels for up to 8 months (the last time point studied) despite withdrawal of allergen exposure. Memory IgE responses to booster exposures were robust after 3, 5 or 8 months of allergen withdrawal. Furthermore, significant clinical reactivity to oral hazelnut challenge, and hypothermia responses were demonstrable at each of these time points. Long-lasting spleen cell memory IL-4 responses to hazelnut were detectable in these mice explaining the mechanism of sustenance of IgE responses and clinical sensitization.

CONCLUSIONS

Hazelnut allergy once established persists for long periods, despite withdrawal of allergen exposure, due to long-lasting, memory IgE and IL-4 responses.

Digested Ara h 1 has sensitizing capacity in Brown Norway rats

BACKGROUND

Food allergies are a public health issue of growing concern, with peanuts in particular being associated with severe reactions. The peanut allergen, Ara h 1, belongs to the cupin plant food allergen family, which, unlike other structural families, appears to be broken down rapidly following gastrointestinal digestion.

OBJECTIVE

Using Ara h 1 as a model allergen, the ability of digested protein to sensitize has been investigated.

METHODS

Ara h 1 was purified from whole roasted peanuts. Intact Ara h 1 was digested in an in vitro model, simulating the human gastrointestinal digestion process. Digestion products were analysed for peptide sizes and their ability to aggregate. Brown Norway (BN) rats, used as an animal model, were immunized with purified intact Ara h 1 or the gastrointestinal digestion products thereof. The sensitizing capacity was evaluated by analyses of specific antibody (IgG1, IgG2a and IgE) responses and ability to trigger mediator release of rat basophilic leukaemia (RBL)-2H3 cells.

RESULTS

The present study showed that Ara h 1 was broken down, resulting in peptide fragments of sizes<2.0 kDa, of which approximately 50% was in aggregated complexes of Mr up to 20 kDa. Ara h 1 digesta were shown to have sensitizing capacity in BN rats, being capable of inducing specific IgG and IgE antibodies. The IgE response was functional, having the capacity to induce specific degranulation of RBL cells.

CONCLUSION

From this study, it can be concluded that lability of a food allergen to gastrointestinal digestion does not necessarily abrogate its allergenic sensitizing potential.

Determination of peanut allergens in cereal-chocolate-based snacks: metal-tag inductively coupled plasma mass spectrometry immunoassay versus liquid chromatography/electrospray ionization tandem mass spectrometry

A comparison of two methods for the identification and determination of peanut allergens based on europium (Eu)-tagged inductively coupled plasma mass spectrometry (ICP-MS) immunoassay and on liquid chromatography/electrospray ionization tandem mass spectrometry (LC/ESI-MS/MS) with a triple quadrupole mass analyzer was carried out on a complex food matrix like a chocolate rice crispy-based snack. The LC/MS/MS method was based on the determination of four different peptide biomarkers selective for the Ara h2 and Ara h3/4 peanut proteins. The performance of this method was compared with that of a non-competitive sandwich enzyme-linked immunosorbent assay (ELISA) method with ICP-MS detection of the metal used to tag the antibody for the quantitative peanut protein analysis in food. The limit of detection (LOD) and quantitation of the ICP-MS immunoassay were 2.2 and 5 microg peanuts g(-1) matrix, respectively, the recovery ranged from 86 +/- 18% to 110 +/- 4% and linearity was proved in the 5-50 microg g(-1) range. The LC/MS/MS method allowed us to obtain LODs of 1 and 5 microg protein g(-1) matrix for Ara h3/4 and Ara h2, respectively, thus obtaining significantly higher values with respect to the ELISA ICP-MS method, taking into account the different expression for concentrations. Linearity was established in the 10-200 microg g(-1) range of peanut proteins in the food matrix investigated and good precision (RSD <10%) was demonstrated. Both the two approaches, used for screening or confirmative purposes, showed the power of mass spectrometry when used as a very selective detector in difficult matrices even if some limitations still exist, i.e. matrix suppression in the LC/ESI-MS/MS procedure and the change of the Ag/Ab binding with matrix in the ICP-MS method.

Adolescents' experiences of being food-hypersensitive: a qualitative study

BACKGROUND

Experiencing or being at risk of adverse reactions to certain food items is a common health issue, especially among children and adolescents. Research has shown that living with the risk of food reactions and always having to take measures to avoid certain food in one's diet has a negative impact on quality of life. The aim of this study was to illuminate adolescents' experiences of being food hypersensitive.

METHODS

Three focus group interviews and six individual interviews were carried out with all together 17 adolescents, 14-18 years of age, who had exclusion diets at school due to food hypersensitivity. The interviews were taped and transcribed verbatim and a qualitative content analysis was carried out.

RESULTS

Five categories with subcategories, and one pervading theme, emerged. The categories were: Perceiving oneself as being particular, Feeling constrained, Experiencing others' ignorance, Keeping control, and Feeling it's okay. A pervading theme was conceptualised as Striving to normalise the experience of being food-hypersensitive. The adolescents regarded themselves as competent and courageous, but also described how they avoided the extra attention it implied to ask for special food considerations taken into account. Their self-conceptions were probably essential for their management of and attitude toward the hypersensitivity condition. They felt deprived, and those at risk of severe food reactions experienced insecurity and fear. Feelings of being disregarded were expressed, as well as facing unreliability and a lack of understanding from others. The continual work of constant vigilance and decision-making was described as time-consuming and frustrating. However, the adolescents also experienced considerate and supportive surroundings and were at pains to tone down the negative experiences and consequences of being food-hypersensitive.

CONCLUSION

Food avoidance by itself, and not only the somatic food reactions, brings about consequences with significant impacts on adolescents' lives. The findings from this study have implications for all of those who deal with adolescents who are food-hypersensitive, and not only health professionals. A deeper insight into adolescents' experiences gives an understanding which can improve the care-givers' efforts.

First Total Synthesis of Vialinin A, a Novel and Extremely Potent Inhibitor of TNF-α Production

Vialinin A, a powerful inhibitor (IC50 90 pM) of TNF-alpha production, was synthesized from sesamol in 11 steps with 28% overall yield. The key reactions include a double Suzuki coupling of electron-rich aryl triflate with phenylboronic acid and an oxidative deprotection of bis-MOM ether. In addition, the related synthetic studies also suggest the necessity for structural revision of ganbajunin C, a positional isomer of vialinin A.

The importance of dietary control in the development of a peanut allergy model in Brown Norway rats

This report describes the further development of a peanut allergy model in Brown Norway (BN) rats and in particular the importance of allergen-free breeding of the laboratory animals for the allergen to be used. For this purpose BN rats were bred for 3 generations on soy- and peanut-free feed since it is known that the legumes peanut and soy are cross-reactive. In addition, the effect of cholera toxin (CT), an oral adjuvant often used to increase the sensitivity of food allergy models, was investigated in the BN rat model. BN rats that were bred on both soy- and peanut-free feed could be sensitized orally to peanut (all exposed rats developed peanut-specific IgE, IgG2a and IgG1) and the adjuvant CT could only enhance this sensitization to a limited extent. We also found different protein recognition patterns against purified peanut allergens (Ara h1, Ara h2 and Ara h3) between intraperitoneally (i.p.) and orally sensitized BN rats. Orally sensitized rats recognized all tested allergens whereas i.p. sensitized rats only recognized Ara h1 and Ara h2. Our conclusion is that a model for food allergy should preferably be (A) oral and (B) if possible without the use of adjuvantia. Our model in BN rats unites these preferred characteristics. In addition, we show the importance of dietary control when conducting oral sensitization studies. Special attention must be paid to unscheduled dietary pre-exposure of the animals to the protein under investigation to obtain optimal oral sensitization.

Incorporating a gender dimension in food allergy research: a review

Sex and gender are the major determinants of health and disease in both men and women. The aim of this review paper was to examine differences in gender and sex in relation to the prevalence and effects of food allergy. There are still major gaps in our knowledge about the kinds of processes which shape men's and women's perceptions and experiences of food allergy. The expression and experience of health and illness may be moderated by variables such as biological vulnerability, exposure to health risks, perception of symptoms, evaluation of risk, information processing and role expectations. This review highlights the complex links between biological sex, gender, and health in general and offers a synthesis of how these may interact to produce sex and gender differences in biopsychosocial manifestations of food allergy. Implications for research and public health practice are discussed.

Vialinin B, a novel potent inhibitor of TNF-α production, isolated from an edible mushroom, Thelephora vialis

A novel dibenzofuran compound designated vialinin B was isolated from dry fruiting bodies of an edible mushroom, Thelephora vialis, and potently inhibits TNF-alpha production in RBL-2H3 cells (IC(50)=0.02nM) and is a promising anti-allergic agent.

Novel foods to treat food allergy and gastrointestinal infection

The gastrointestinal tract communicates directly with the external environment. Necessary nutrients must be absorbed and commensal bacteria tolerated, and foreign proteins, antigens, and pathogens must be simultaneously excluded or destroyed. Immaturity or disruption of the mucosal immune defenses increases vulnerability to food allergy, intolerance, and infectious disease. Diseases resulting from ingested foreign proteins and organisms are increasing and cause morbidity and mortality worldwide. There is no specific treatment for food allergy other than avoidance. Vaccination for infectious disease is limited by the cost and logistics of distribution and administration, particularly in developing countries. Novel strategies are being explored to modulate the gut mucosal immune system by altering protein expression in food. Crops are being developed to remove deleterious allergens to prevent immunogenic exposure while preserving nutritional quality. Local food plants that express protein fragments of pathogens might provide an effective means to stimulate gut mucosal immunity while increasing vaccine accessibility.

How important is inadvertent ingestion of hazardous substances at work?

Much is known about human exposure to workplace hazardous substances by inhalation and from skin contact, but there has been little systematic research into ingestion of hazardous substances used at work. This review attempts to identify whether inadvertent ingestion of hazardous substances is an important route of exposure in the workplace and examines possible methods that could be used to quantify ingestion exposure. A number of papers highlight jobs and substances where inadvertent ingestion may be important, typically through case reports or from a theoretical analysis. These scenarios involve exposure to some metals or metal compounds, pharmaceuticals, pesticides, some infectious agents, unsealed radioactive sources and some high molecular weight allergens. In total we estimate that about 4.5 million workers in the UK could have some regular non-trivial intake of hazardous substances by inadvertent ingestion. A conceptual analysis of inadvertent ingestion exposure highlights the role of hand-to-mouth and object-to-mouth events as the primary exposure processes. Two exposure 'compartments' are defined: the peri-oral area (i.e. the area of skin around the outside of the mouth) and the oral cavity. Several options are highlighted for exposure-related measurements, including peri-oral wipes, saliva samples, mouth-rinse samples, hand-wipes and under-nail scrapings. Further research is necessary to define which measurements may be most informative. Human behaviour has a key role in determining inadvertent ingestion exposure. For example, some people are habitual nail biters or repeatedly touch their mouth, both of which will increase the chance of ingesting contaminants on their hands. The frequency that people touch their face is dependant on the circumstances of their work and probably the degree of psychological stress they are under. A proper understanding of the importance of these factors will help in designing interventions to reduce the risks from ingesting hazardous substances at work. When making inhalation or dermal exposure measurements we recommend that details of personal behaviours should be recorded so that some estimate of ingestion risks can be inferred. It is possible that inadvertent ingestion of hazardous substances at work may become more important as employers put more emphasis on controlling inhalation and dermal exposures. Further research is necessary to ensure that risk reduction strategies for inadvertent ingestion of hazardous substances are appropriate and effective.

Modulation of Oral Tolerance to Ovalbumin by Dietary Protein in Mice

This study sought to determine whether oral tolerance to ovalbumin (OVA), responsible for food allergy, is affected by different amounts of protein intake. For this, 6-wk-old BALB/c mice were fed with low protein (5%, LP), normal protein (20%, NP) and high protein (40%, HP) diets, orally given either OVA (OVA-fed) or water (Water-fed) for 4 d, and then immunized intraperitoneally twice at a 3-wk interval with alum-precipitated OVA. After the last immunization, sera were collected to measure total and OVA-specific IgE by enzyme assay (ELISA). Splenocytes were cultured and stimulated with concanavalin A (Con A), lipopolysaccharide (LPS) or OVA and assayed for 3H-thymidine incorporation. The culture supernatants from their splenocytes stimulated with OVA were analyzed for interleukin (IL)-4, interferon (IFN)-gamma, and IL-12. Total IgE was significantly higher in OVA-fed HP groups as compared to NP and LP groups (p<0.05). The highest and the lowest OVA-specific IgE were observed in HP and LP diet groups, respectively (p<0.05). OVA-fed mice receiving the LP diet demonstrated significantly lower IL-4 as compared to the other two groups (p<0.05), while IFN-gamma was significantly higher in the LP compared to the HP group (p<0.05). Levels of IL-12 did not differ among the OVA-fed groups. Splenocytes of OVA-fed mice kept on the LP and HP diet showed significant impairment of proliferation to OVA as compared to the NP group (p<0.01). Proliferation against Con A was impaired in the LP group compared to the NP group (p<0.05) but not in Water-fed groups. However, it was higher against LPS in the HP than the LP group (p<0.05) both in Water-fed and OVA-fed animals. All these findings indicate that established oral tolerance to OVA is clearly affected by the amount of protein diet. They support the suggestion that dietary protein plays an important role(s) in IgE-mediated food allergies.

Altered allergic cytokine and antibody response in mice treated with Bisphenol A

The objective of this study was to elucidate if Bisphenol A (BPA) administration modulates T helper (Th) cell component of immune responses in a mouse challenged with ovalbumin (OVA), a major food antigen. BALB/c mice, (6 weeks old, female) were orally given either OVA (OVA-fed) or water (Water-fed), immunized intraperitoneally with OVA and injected with either BPA in corn oil or the vehicle alone. After subsequent 2nd immunization, serum titers of total IgE, OVA-specific IgE, IgG, IgG1 IgG2a and ability of their splenocytes for production of interferon (IFN) -gamma, interleukin (IL) -4 and IL-12 were examined by ELISA. Lymphocyte proliferation assay against concanavalin A (Con A) or OVA was also performed for 3H-Thymidine incorporation. In Water-fed groups, treatment with BPA resulted in lower titers of total IgE (P<0.01) and higher levels IgG2a (P<0.05) followed by a higher IFN-gamma (P<0.05) and IL-12 (P<0.05) with an intact IL-4. When OVA-fed groups were examined, the compound did not change production of total and OVA-specific IgE and -IgG2a but resulted in lower production of IFN-gamma (P<0.05). Also, BPA resulted in impaired lymphocyte proliferation to Con A in Water-fed groups (P<0.05) but not in tolerated animals. The findings indicate that BPA results in augmentation of Th1 immune responses but no significant effect on an established tolerance to OVA.

Food hypersensitivity in patients with seasonal rhinitis in Ankara

BACKGROUND

Food hypersensitivity (FH) affects 1-2 % of the adult population and is more common in atopic individuals. The aim of this study was to determine the frequency of FH and risk factors for its development in patients with seasonal rhinitis (SR) in our allergy clinic.

METHODS

We performed a retrospective study based on the medical records of 774 patients out of 955 patients diagnosed with SR in an adult allergy clinic between 1 January 1991 and 31 December 2003.

RESULTS

The mean age of the patients was 29.1 +/- 9.29 and 62.7 % were females. The most common major complaints were due to nasal symptoms in 82.3 %. The mean duration of SR was 6.8 +/- 6.8 years. Patients were symptomatic for a mean of 3.5 +/- 1.7 months per year. Skin prick tests (SPT) with common aeroallergens were positive in 685 patients (90.3 %), and the most common sensitivity was against timothy (85.1 %). The most common accompanying allergic disease was FH in 14 %. FH according to history and the results of SPT performed with food allergens were discordant. The most common clinical manifestations of FH were oral allergy (49.1 %) and cutaneous symptoms (38.9 %). Risk factors for the development of FH in patients with SR were dermatological symptoms, rhinitis duration > 5 years, symptom duration > 3 months per year, SPT reactivity to Artemisia vulgaris, tree pollen allergens (Corylus avellena, Betula verrucosa), and bee allergy.

CONCLUSION

FH was the most common (14 %) accompanying allergic disease in patients with SR. SPT with food allergens have limited diagnostic value for food allergy and/or intolerance. Risk factors for developing FH in patients with SR in Turkey were dermatological symptoms, duration of rhinitis > 5 years, duration of rhinitis symptoms > 3 months per year, and SPT reactivity to Corylus avellena.

A novel approach for the detection of potentially hazardous pepsin stable hazelnut proteins as contaminants in chocolate-based food

Contamination of food products with pepsin resistant allergens is generally believed to be a serious threat to patients with severe food allergy. A sandwich type enzyme-linked immunosorbent assay (ELISA) was developed to measure pepsin resistant hazelnut protein in food products. Capturing and detecting rabbit antibodies were raised against pepsin-digested hazelnut and untreated hazelnut protein, respectively. The assay showed a detection limit of 0.7 ng/mL hazelnut protein or <1 microg hazelnut in 1 g food matrix and a maximum of 0.034% cross-reactivity (peanut). Chocolate samples spiked with 0.5-100 microg hazelnut/g chocolate showed a mean recovery of 97.3%. In 9/12 food products labeled "may contain nuts", hazelnut was detected between 1.2 and 417 microg hazelnut/g food. It can be concluded that the application of antibodies directed to pepsin-digested food extracts in ELISA can facilitate specific detection of stable proteins that have the highest potential of inducing severe food anaphylaxis.

Health-related quality of life among adolescents with allergy-like conditions - with emphasis on food hypersensitivity

BACKGROUND

It is known that there is an increase in the prevalence of allergy and that allergic diseases have a negative impact on individuals' health-related quality of life (HRQL). However, research in this field is mainly focused on individuals with verified allergy, i.e. leaving out those with self-reported allergy-like conditions but with no doctor-diagnosis. Furthermore, studies on food hypersensitivity and quality of life are scarce. In order to receive information about the extent to which adolescent females and males experience allergy-like conditions and the impact of these conditions on their everyday life, the present study aimed to investigate the magnitude of self-reported allergy-like conditions in adolescence and to evaluate their HRQL. Special focus was put on food hypersensitivity as a specific allergy-like condition and on gender differences.

METHODS

In connection with lessons completed at the children's school, a study-specific questionnaire and the generic instrument SF-36 were distributed to 1488 adolescents, 13-21 years old (response rate 97%).

RESULTS

Sixty-four per cent of the respondents reported some kind of allergy-like condition: 46% reported hypersensitivity to defined substances and 51% reported allergic diseases (i.e. asthma/wheezing, eczema/rash, rhino-conjunctivitis). A total of 19% reported food hypersensitivity. Females more often reported allergy-like conditions compared with males (p < 0.001). The adolescents with allergy-like conditions reported significantly lower HRQL (p < 0.001) in seven of the eight SF-36 health scales compared with adolescents without such conditions, regardless of whether the condition had been doctor-diagnosed or not. Most adolescents suffered from complex allergy-like conditions.

CONCLUSIONS

The results indicate a need to consider the psychosocial impact of allergy-like conditions during school age. Further research is needed to elucidate the gender differences in this area. A team approach addressing better understanding of how allergy-like conditions impair the HRQL may improve the management of the adolescent's health problems, both in health-care services and in schools.

Novel foods to treat food allergy and gastrointestinal infection

The gastrointestinal tract communicates directly with the external environment. Necessary nutrients must be absorbed and commensal bacteria tolerated, and foreign proteins, antigens, and pathogens must be simultaneously excluded or destroyed. Immaturity or disruption of the mucosal immune defenses increases vulnerability to food allergy, intolerance, and infectious disease. Diseases resulting from ingested foreign proteins and organisms are increasing and cause morbidity and mortality worldwide. There is no specific treatment for food allergy other than avoidance. Vaccination for infectious disease is limited by the cost and logistics of distribution and administration, particularly in developing countries. Novel strategies are being explored to modulate the gut mucosal immune system by altering protein expression in food. Crops are being developed to remove deleterious allergens to prevent immunogenic exposure while preserving nutritional quality. Local food plants that express protein fragments of pathogens might provide an effective means to stimulate gut mucosal immunity while increasing vaccine accessibility.

Enteromorpha compressa (L.) Greville an edible green alga as a source of antiallergic principle (S)

Enteromorpha compressa a marine green algal species grows extensively in North coastal Andhra Pradesh. Besides its nutritional importance it has also been identified as source of anti-anaphylactic compound(s).E. compressa extracts alleviated the IgE levels raised against ovalbumin and other allergens in mice. Further,Enteromorpha extract also significantly down regulated the serum IgE levels in different murine models irrespective of their genetic background. The results obtained in this study suggest thatE. compressa extract has compound(s), which inhibit IgE immune response and may have potential in curing various types of allergies.

Animal models to detect allergenicity to foods and genetically modified products: workshop summary

Respiratory allergy and allergy to foods continue to be important health issues. There is evidence to indicate that the incidence of food allergy around the world is on the rise. Current estimates indicate that approximately 5% of young children and 1-2% of adults suffer from true food allergy (Kagan 2003). Although a large number of in vivo and in vitro tests exist for the clinical diagnosis of allergy in humans, we lack validated animal models of allergenicity. This deficiency creates serious problems for regulatory agencies and industries that must define the potential allergenicity of foods before marketing. The emergence of several biotechnologically derived foods and industrial proteins, as well as their potential to sensitize genetically predisposed populations to develop allergy, has prompted health officials and regulatory agencies around the world to seek approaches and methodologies to screen novel proteins for allergenicity.