Australian research into peanuts during pregnancy
Many reports over recent months and years have provided conflicting information in relation to whether maternal peanut ingestion during pregnancy might influence sensitization of the off-spring in later life. A team of Australian-based immunologists have added to the body of knowledge in this area using data from a population-based longitudinal cohort study with 16 years follow-up.
Over three hundred participants were recruited at birth as part of an infant health study. Maternal antenatal peanut consumption was documented at the time of recruitment, and peanut and rye sensitization in the off-spring was determined by measurement of serum-specific IgE at age 16 years.
A high proportion (14%) of the cohort was found to be sensitised to peanut, but no association was found between antenatal peanut ingestion and peanut sensitisation. Interestingly, the results did indicate a strong association between antenatal peanut ingestion and decreased risk of peanut and rye sensitisation in those without a family history of allergy. In those with a family history of asthma, there was an increased risk of rye sensitisation with antenatal peanut ingestion and this was said to be possibly due to a cross-reaction of carbohydrate epitopes common to rye and peanut allergens.
The authors concluded that peanut ingestion may influence the development of IgE antibody to cross-reacting carbohydrate epitopes in later life with genetic factors potentially impacting on this association.
Reference: Kemp et al. 2010. Clinical and Experimental Allergy. DOI: 10.1111/j.1365-2222.2010.03668.x.
Allergen issues with functional foods
Fonterra’s Wh2ole® water was the focus of a study by Associate Professor Rohan Ameratunga and Dr See-Tarn Woon of Auckland City Hospital into the allergenic properties of functional foods. The study was prompted after two cow’s milk allergic children suffered anaphylactic reactions following consumption of the water, which contained the dairy-derived functional ingredient ‘ClearProtein’.
While the milk component was clearly labelled on the fortified water, the study revealed the product contained at least three times the concentration of beta lactoglobulin as standard cow’s milk. This lead the authors to brand Wh2ole® an example of a ‘hyperallergenic’ food created through the use of modern technology. They warn that new methods allowing the addition of food proteins to a broader range of consumer products brings a greater risk of inadvertent allergen exposure to allergic individuals, and urge all stakeholders to work together to manage these risks.
Fonterra has responded to the study by advising international customers of the potential need to identify the dairy content of foods containing specialised dairy proteins beyond the requirements of food labelling laws. With companies increasingly using dairy-based ingredients in products that do not necessarily appear to be dairy foods, there is a need to ensure consumers are adequately informed that these products contain dairy.
Wh2ole® was removed from the market in April 2010 because sales were not meeting expectations, and Fonterra is not currently producing any consumer products containing specialised dairy proteins.
Study Reference: Ameratunga & Woon. 2010. Allergy Asthma and Clinical Immunology. Vol 6(1) pp. 33. DOI:10.1186/1710-1492-6-33
Additional Source: www.fonterra.com
More funding for novel allergy drug development
The Wellcome Trust has granted £390,000 (approximately $A596,000) funding to scientists at St George’s, University of London and the University of Manchester to explore a new class of experimental drugs that block the trigger of allergic reactions before symptoms show.
The funding will help the researchers explore a novel finding from a study being conducted in a larger project also funded by the Wellcome Trust. In 2007, a £4.3 million ($A6.66 million) Seeding Drug Discovery award was granted to the team to investigate chemical compounds known as Allergen Delivery Inhibitors (ADIs). These compounds target the substances that can trigger allergies and asthma attacks directly, potentially preventing the cascade of events that lead to an allergic reaction. Existing medications for relief of allergy symptoms target the allergy cascade at a lower level where it has proven more difficult to modify the outcome of the reaction.
Experimental work on one of the first ADIs, developed to target dust mite allergens, has shown these inhibitors reduce the intensity of reactions in established allergy and can even prevent allergy from occurring.
The research team report they have made great progress towards developing a drug that will be safe and effective in humans, although a commercialised ADI product is still some way off. Once a lead compound has been identified and refined, its safety, tolerability and efficacy will be assessed in human clinical trials.
How ‘Food Allergy Herbal Formula 2’ prevents allergic reactions
Work is continuing on the Chinese herbal formula, food allergy herbal formula 2 (FAHF-2) which has been shown to protect against peanut anaphylaxis in mice. Recently published studies have looked at the underlying mechanisms responsible for the observed protective effects.
The studies, carried out by researchers at the Mount Sinai School of Medicine, New York, investigated the metabolic responses of mice with peanut allergy following treatment with FAHF-2 for 7 weeks and subsequent peanut challenge one day and four weeks after conclusion of the treatment period. All peanut allergic mice not treated with FAHF-2 developed anaphylaxis, whereas all those treated with FAHF-2 were protected against anaphylaxis after the peanut challenge, both one day after therapy and 4 weeks later.
Results from blood sample analyses indicate FAHF-2 reduces basophil and mast cell numbers, and suppresses IgE-mediated mast cell activation. The authors believe these factors may contribute to the protection against peanut anaphylaxis conferred by the herbal formulation.
Mast cells and basophils play a central role in IgE-mediated allergic reactions including anaphylaxis. They are able to release potent inflammatory mediators, such as histamine, proteases and cytokines that act on the circulatory system, smooth muscle, connective tissue, mucous glands and inflammatory cells.
Reference: Song,et al. 2010. The Journal of Allergy and Clinical Immunology. Vol 126(6). Pp1208-1217. DOI: 10.1016/j.jaci.2010.09.013
Summary supplement to NIAID Allergy Guidelines
As reported in last month’s issue of the Allergen Bureau eNews, Guidelines for the Diagnosis and Management of Food Allergy were published by a NIAID-sponsored Expert Panel in December 2010. A summary supplement to these Guidelines was published online in the Journal of Allergy and Clinical Immunology at the same time, and is freely available for download.
The Guidelines provide 43 concise clinical recommendations and additional guidance on points of current controversy in patient management. Gaps in the current scientific knowledge to be addressed through future research are also identified in the Guidelines. The summary is a comprehensive, fourteen page synopsis which follows numbered sections of the Guideline document, providing an ‘in brief’ description of most of the recommendations.
In addition to the introduction, the broad spectrum of topics relating to food allergy is covered in five sections. Topics include the definitions, prevalence, natural history and diagnosis of food allergy, plus the management of anaphylaxis and other acute or non-acute reactions to foods. Useful prevalence data for peanut, tree nuts, seafood, milk and egg allergies in the United States are provided in the Summary document, with a reference to the Guidelines for more detail.
In developing the Guidelines, the NIAID-sponsored Expert Panel have focused on diseases that are defined as food allergy, including both IgE-mediated reactions to food and some non-IgE-mediated reactions to food. However they do not discuss coeliac disease, as clinical guidelines for coeliac disease already exist.
Both the summary document and the full guidelines can be accessed via the NIAID website, and a lay language synopsis of the guidelines is expected to be available soon.
Reference: Boyce et al. 2010. Journal of Allergy and Clinical Immunology. Vol.126(6 Suppl):S1-58. DOI:10.1016/j.jaci.2010.10.008
Standardised guidelines for management of cow’s milk allergy
The World Allergy Organization (WAO) Food Allergy Special Committee’s Diagnosis and Rationale for Action against Cow’s Milk Allergy (DRACMA) guidelines were published in the April 2010 issue of the WAO Journal. The consensus-based approach to the development of these guidelines was presented at a meeting on Adverse Reactions to Bovine Proteins in Italy in early 2010. A summary report of the workshop has recently been published and is freely available for download.
Under the two banners of basic science and clinical science, the report details several aspects of cow’s milk allergy. Topics discussed under the basic science heading include the different allergenic proteins in cow’s milk, epidemiology and prevalence of allergy to these proteins, and pathogenesis of cow’s milk allergy. The clinical science section deals with immediate and delayed reactions and includes a table listing the extensive clinical manifestations of cow’s milk allergy plus a listing of some more unusual presentations of the allergy.
A useful summary is provided on page six of the 22 page document, in a boxed section entitled ‘What DRACMA brings to the treatment of cow’s milk allergy’.
DRACMA aims to provide leadership in the area of management of cow’s milk allergy by coordinating the multidisciplinary approaches employed to tackle the problem of cow’s milk allergy world-wide, and by implementing consensus-based clinical practice guidelines to disseminate the body of knowledge, including foreseeable breakthroughs.
Reference: Fiocchi et al. 2010. Journal of Allergy and Clinical Immunology. Vol.126(6) pp.1119-1128.e12.
Kiwifruit varieties not equally allergenic
Kiwifruit is regarded as an ’emerging allergen’ in many countries due to the increasing number of individuals experiencing mild oral symptoms, characterised by rashes and mouth inflammation. Severe systemic reactions, including anaphylaxis, have also been reported in relation to kiwifruit. A new study has examined the differences in immune response to six kiwifruit varieties.
The varieties used in the study included the most widely sold cultivar ‘Hayward’, the popular ‘Zespri Gold’, the more recently introduced ‘Jinatao’ and ‘Summer 3373’ varieties, plus two other varieties that are reported as likely to become available on the market in future.
The 37 study participants comprised outpatients with known kiwifruit allergy recruited from the University Medical Centre in Zurich and University Hospital Zurich. Results of skin prick tests showed the Hayward and Eriantha varieties triggered the most marked reactions while Zespri Gold and Summer varieties were responsible for the mildest allergenic reactions.
Eleven of the participants also undertook a food challenge where they were gradually given small amounts of the Hayward, Zespri Gold and Summer varieties. Two of the participants experienced severe reactions during the challenge, with the Hayward variety appearing to be the most allergenic of those tested. Two participants in the food challenge experienced no adverse reactions.
Despite the findings from this small-scale study leading to suggestions that those with kiwifruit allergies may be able to selectively introduce certain varieties of the fruit into their diets, the researchers stressed that further investigations amongst a wider population is needed before any such recommendations could be made.
Reference: Le et al. 2010. Journal of Allergy and Clinical Immunology. DOI:10.1016/j.jaci.2010.10.003
Corn protein promising for gluten-free bread
Gluten plays a crucial role in giving bread its chewy, elastic texture and has proven difficult to replace when formulating gluten-free bread. A team of chemists working with the United States Department of Agriculture have been seeking to mitigate these difficulties, and have recently reported positive findings using defatted corn protein.
The team began working with a dough comprising zein (a class of prolamine protein found in maize), together with starch, hydroxypropyl methylcellulose, sugar, salt, yeast and water. However when they tried to bake the mixture as leavened rolls, the dough became flat, prompting further experimental work.
Through the use of bench-scale defatting of the zein component the total lipid content was reduced from 8 to 6.6%. Aggregation experiments and microscopy showed when surface-defatted, the zein particles aggregated more easily and also lowered the temperature at which protein cross-linking occurred by 2°C.
Following the defatting process, the dough was more similar to wheat dough and formed free-standing rolls that resembled rolls made using wheat flour. As a result, the researchers are hopeful their work could lead to the development of more palatable gluten-free breads.
Reference: Schober et al. 2010. Journal of Cereal Science Vol 52(3). Pp 417-425 DOI:10.1016/j.jcs.2010.07.004
Annual review of advances in allergy research
Each year, Sicherer and Leung review the highlights of the scientific advances in anaphylaxis and hypersensitivity reactions to foods, drugs, and insects that were published in the Journal of Allergy and Clinical Immunology throughout the preceding year. These reviews serve as useful references to keep up to date with advances in this field and provide a ‘one-stop’ summary of key research published in this journal. Their latest edition relating to research published throughout 2010 is now available.
Epidemiologic studies published in 2010 that indicate the prevalence of peanut allergy among children is now more than 1%. Throughout the year, there was an accumulation of evidence that exposure to food allergens earlier in life, rather than delayed introduction of these foods, might improve allergy outcomes.
Advances in food allergy diagnosis mentioned in the latest review include improved insights into prognosis and estimation of severity through component-resolved diagnostics and characterization of IgE binding to specific epitopes. Research into new and improved treatments for food allergy includes oral and epicutaneous immunotherapy, both of which show promise to-date.
The review of 2010 research also highlights studies into other aspects of allergy and asthma that are not directly related to food allergy but may have an impact on future management and treatment of the symptoms of food allergy.
Reference: Sicherer & Leung 2010. Journal of Allergy and Clinical Immunology. DOI: 10.1016/j.jaci.2010.11.024.