Common ragweed (Ambrosia artemisiifolia L.): allergenicity and molecular characterization of pollen after plant exposure to elevated NO2.

Ragweed pollen is the main cause of allergenic diseases in Northern America, and the weed has become a spreading neophyte in Europe. Climate change and air pollution are speculated to affect the allergenic potential of pollen. The objective of this study was to investigate the effects of NO2 , a major air pollutant, under controlled conditions, on the allergenicity of ragweed pollen. Ragweed was exposed to different levels of NO2 throughout the entire growing season, and its pollen further analysed. Spectroscopic analysis showed increased outer cell wall polymers and decreased amounts of pectin. Proteome studies using two-dimensional difference gel electrophoresis and liquid chromatography-tandem mass spectrometry indicated increased amounts of several Amb a 1 isoforms and of another allergen with great homology to enolase Hev b 9 from rubber tree. Analysis of protein S-nitrosylation identified nitrosylated proteins in pollen from both conditions, including Amb a 1 isoforms. However, elevated NO2 significantly enhanced the overall nitrosylation. Finally, we demonstrated increased overall pollen allergenicity by immunoblotting using ragweed antisera, showing a significantly higher allergenicity for Amb a 1. The data highlight a direct influence of elevated NO2 on the increased allergenicity of ragweed pollen and a direct correlation with an increased risk for human health.

Decreased immunoglobulin E (IgE) binding to cashew allergens following sodium sulfite treatment and heating.

Cashew nut and other nut allergies can result in serious and sometimes life-threatening reactions. Linear and conformational epitopes within food allergens are important for immunoglobulin E (IgE) binding. Methods that disrupt allergen structure can lower IgE binding and lessen the likelihood of food allergy reactions. Previous structural and biochemical data have indicated that 2S albumins from tree nuts and peanuts are potent allergens, and that their structures are sensitive to strong reducing agents such as dithiothreitol. This study demonstrates that the generally regarded as safe (GRAS) compound sodium sulfite effectively disrupted the structure of the cashew 2S albumin, Ana o 3, in a temperature-dependent manner. This study also showed that sulfite is effective at disrupting the disulfide bond within the cashew legumin, Ana o 2. Immunoblotting and ELISA demonstrated that the binding of cashew proteins by rabbit IgG or IgE from cashew-allergic patients was markedly lowered following treatment with sodium sulfite and heating. The results indicate that incorporation of sodium sulfite, or other food grade reagents with similar redox potential, may be useful processing methods to lower or eliminate IgE binding to food allergens.

Effect of heating and glycation on the allergenicity of 2S albumins (Ara h 2/6) from peanut.

BACKGROUND: Peanut allergy is one of the most common and severe food allergies, and processing is known to influence the allergenicity of peanut proteins. We aimed to establish the effect of heating and glycation on the IgE-binding properties and biological activity of 2S albumins (Ara h 2/6) from peanut. METHODOLOGY/PRINCIPAL FINDINGS: Native Ara h 2/6 was purified from raw peanuts and heated in solution (15 min, 110°C) in the presence or absence of glucose. Ara h 2 and 6 were also purified from roasted peanut. Using PBMC and sera from peanut-allergic patients, the cellular proliferative potency and IgE reactivity (reverse EAST inhibition) and functionality (basophil degranulation capacity) of allergens were assessed. Heating Ara h 2/6 at 110°C resulted in extensive denaturation, hydrolysis and aggregation of the protein, whilst Ara h 2 and 6 isolated from roasted peanut retained its native conformation. Allergen stimulation of PBMC induced proliferation and Th2 cytokine secretion which was unaffected by thermal processing. Conversely, IgE reactivity and functionality of Ara h 2/6 was decreased by heating. Whilst heating-glycation further reduced the IgE binding capacity of the proteins, it moderated their loss of histamine releasing capacity. Ara h 2 and 6 purified from roasted peanut demonstrated the same IgE reactivity as unheated, native Ara h 2/6. CONCLUSIONS/SIGNIFICANCE: Although no effect of processing on T-cell reactivity was observed, heat induced denaturation reduced the IgE reactivity and subsequent functionality of Ara h 2/6. Conversely, Ara h 2 and 6 purified from roasted peanut retained the structure and IgE reactivity/functionality of the native protein which may explain the allergenic potency of this protein. Through detailed molecular study and allergenicity assessment approaches, this work then gives new insights into the effect of thermal processing on structure/allergenicity of peanut proteins.

Allergen specific responses in cord and adult blood are differentially modulated in the presence of endotoxins.

BACKGROUND: Endotoxins are common contaminants in allergen preparations and affect antigen-specific cellular responses. Distinct effects of endotoxin on cells in human umbilical cord and adult blood are poorly defined. OBJECTIVES: To examine the effect of endotoxins in allergen preparations on cellular responses in human cord and peripheral blood (PB). METHODS: The endotoxin content in beta lactoglobulin (BLG), the peanut allergen Ara h 1 and the major birch pollen allergen Bet v 1 was assessed. Proliferation and cytokine response of mononuclear cells towards contaminated and lipopolysaccharide (LPS)-free allergens were evaluated at different time-points. Fractions of contaminated BLG were generated and assayed on their immuno-stimulatory capacity. The involvement of toll-like receptor (TLR) 2 and 4 was investigated by blocking antibodies and TLR-transfected human embryonic kidney cells. RESULTS: The proliferative response of cord blood (CB)-derived mononuclear cells towards allergen-preparations at day 3 was related to the level of LPS contamination. At day 7, proliferation was also detected in the absence of endotoxin. Cytokine production in CB was strongly affected by the content of endotoxin, TLR-4 dependent and not related to the allergen content. Allergen- and endotoxin-induced proliferative responses were generally significantly higher in CB than in adult blood. CONCLUSION: Endotoxins in allergen preparations confound allergen-specific cellular responses. The impact of these contaminations varies with the blood source (CB vs. PB), the type of allergen and is time- and dose-dependent.

Health-economic analyses of subcutaneous specific immunotherapy for grass pollen and mite allergy.

OBJECTIVE: To investigate the health and monetary consequences of treating allergy with specific immunotherapy (SIT) compared with symptomatic treatment/standard care among patients with grass pollen or mite allergy. METHODS: We performed an economic analysis based on 253 grass- and/or mite allergic patients who started SIT from 1.1.1996 to 1.1.2002 at the Allergy Unit, Aarhus University Hospital and at a specialist practice in Aarhus. Relevant data were collected before, during and after SIT treatment from the national health service based on each patient's personal identification number and medical records and from a specifically designed questionnaire. A cost-benefit analysis including direct and indirect costs before, during and after SIT was performed. In addition direct costs were related to the clinical effect (improvement in well-being) in the form of a cost-effectiveness analysis. RESULTS: The direct cost per patient/year before SIT (equivalent to standard care) was DKK 2,580. The investment in SIT was DKK 27,545 (in present values) per patient over a 4-year period. After SIT the cost was reduced to DKK 1,072 per patient/year. In the long term, prospective introduction of SIT incurred additional present-value direct costs of DKK 13,676 per patient treated and DKK 2,784 per patient/year of improved well-being. However, when indirect costs were included in the economic evaluation SIT was shown to be net beneficial. CONCLUSION: This study reveals that SIT is associated with initial resource investments and subsequent resource savings in the long term compared with standard care. When all consequences are measured in monetary terms, and assuming that sick days are associated with a loss of productivity, this analysis suggests that SIT increases societal welfare. This conclusion also holds if there is no loss of productivity.