White Birch Pollen Research Articles

Utilization of Component-Resolved Diagnosis in Precision Allergology

It is very important to identify the causal allergen of each patient in the diagnosis and treatment of allergic diseases. An experimental method of specific IgE testing for single clinically meaningful antigens is called component resolved diagnosis (CRD). Since the introduction of CRD, many single antigens with clinical significance from animal and plant allergenic source have become known. Bet v 1, the major allergen of white birch pollen, can be an indication marker for allergen-specific immunotherapy if the patient is sensitized. Phl p 1, the group I allergen of timothy grass pollen, is an important marker that suggests that patients are truly sensitized to grass pollen. The major allergen of ragweed pollen, Amb a 1 and Art v 1, which is the major allergen of mugwort pollen, are clinically important to distinguish true sensitization. House dust mites have several clinically useful component allergens. Der p 1 and Der p 2 are the initiation molecules in the molecular spreading of allergic diseases caused by house dust mites. Among food allergens, Ara h 2 from peanut, which is closely related to anaphylaxis among several clinical manifestation of peanut allergy. Tri a 19, well known to omega-5 gliadin is important in patients with wheat-dependent exercise-induced anaphylaxis. It is conceivable that the molecular biological concept of CRD methods should lead to ‘patient-customized treatment’ beyond ‘diagnosis’ in the future. Primary prevention of the allergic diseases will apply, which will conceptually be called ‘allergen immunprophylaxis’. This is the right direction of future precision allergology.

A study of cross-reactivity between citrus fruit and pollen allergens in oral allergy syndrome and food-dependent exercise-induced anaphylaxis in Japan

Objectives: Oral allergy syndrome (OAS) associated with citrus fruits has been previously reported. However, in Japan, although rare, citrus allergy is also associated with food-dependent exercise-induced anaphylaxis (FDEIA). This study was done to determine whether different allergens may be involved in these two responses, and to examine cross-reactivity between popular citrus fruits and local pollen allergens. Methods: Twelve patients were studied who had a history of OAS (8 cases) or FDEIA (4 cases), and had positive IgE antibody titers or tested positive with a skin prick test to citrus antigens. Serum immunodetection assays and immunoblot inhibition assays were performed with extracted Valencia orange (rCit s 2), selected antigens in white birch pollen (WBP) and orchard grass pollen (OGP). Results: Immunodetection assays demonstrated an allergen associated with OAS as the 14-kDa protein, Cit s 2. An as yet unidentified 54-kDa protein was demonstrated in FDEIA patients. Cross-reactivity between orange and pollen antigens was confirmed by the following results: 1) Significant correlations between serum specific IgE levels for orange and OGP, 2) Immunoblot inhibition with WBP and OGP pollen antigens against rCit s 2. In Immunoblot inhibition, WBP and OGP both pollen antigens inhibited against rCit s 2. Conclusion: The main allergen of OAS induced by orange was Cit s 2, which has cross-reactivity with WBP and/or OGP in Japanese patients with orange allergy. IgE-binding protein pattern in patients with FDEIA induced by orange were different from that in OAS. A 54-kDa protein was assumed to be a candidate for clinically relevant allergens in the development of the FDEIA.

Possibility for Allergy Immunotherapy with Long Synthetic Peptide of Bet V1

In allergy immunotherapy (AIT) using peptides, although the choice of T-cell epitope in consideration of the HLA type is important, application to all HLA types is difficult. We recently devised a new method to address this problem in AIT for white birch pollinosis, using long-chain synthetic peptides by dividing the sequence of Bet v1a, the major allergen in white birch pollen, into three peptides that overlap by 10 amino acid residues. Theoretically, these peptides contain all possible T-cell epitopes for any HLA type. Further, these peptides show weak allergenicity and are considered less prone to cause anaphylaxis because the three-dimensional structures differ significantly from the native Bet v1a. The combination of these three peptides of Bet v1a appears to provide an effective, safe form of AIT for white birch pollinosis. This method may thus be applicable to other allergens.

Inhaled Birch Pollen Extract Induces Airway Hyperresponsiveness via Oxidative Stress but Independently of Pollen-Intrinsic NADPH Oxidase Activity, or the TLR4–TRIF Pathway

Oxidative stress in allergic asthma may result from oxidase activity or proinflammatory molecules in pollens. Signaling via TLR4 and its adaptor Toll-IL-1R domain-containing adapter inducing IFN-β (TRIF) has been implicated in reactive oxygen species-mediated acute lung injury and in Th2 immune responses. We investigated the contributions of oxidative stress and TLR4/TRIF signaling to experimental asthma induced by birch pollen exposure exclusively via the airways. Mice were exposed to native or heat-inactivated white birch pollen extract (BPEx) intratracheally and injected with the antioxidants, N-acetyl-L-cysteine or dimethylthiourea, prior to sensitization, challenge, or all allergen exposures, to assess the role of oxidative stress and pollen-intrinsic NADPH oxidase activity in allergic sensitization, inflammation, and airway hyperresponsiveness (AHR). Additionally, TLR4 signaling was antagonized concomitantly with allergen exposure, or the development of allergic airway disease was evaluated in TLR4 or TRIF knockout mice. N-acetyl-L-cysteine inhibited BPEx-induced eosinophilic airway inflammation and AHR except when given exclusively during sensitization, whereas dimethylthiourea was inhibitory even when administered with the sensitization alone. Heat inactivation of BPEx had no effect on the development of allergic airway disease. Oxidative stress-mediated AHR was also TLR4 and TRIF independent; however, TLR4 deficiency decreased, whereas TRIF deficiency increased BPEx-induced airway inflammation. In conclusion, oxidative stress plays a significant role in allergic sensitization to pollen via the airway mucosa, but the pollen-intrinsic NADPH oxidase activity and TLR4 or TRIF signaling are unnecessary for the induction of allergic airway disease and AHR. Pollen extract does, however, activate TLR4, thereby enhancing airway inflammation, which is restrained by the TRIF-dependent pathway.

Ragweed pollen activates inflammasome in epidermal keratinocytes and release IL-1beta and IL-18

Pollen is an important trigger for allergic rhinitis, conjunctivitis, and asthma, and is an exacerbating factor for atopic dermatitis (AD). Pollen of white birch and short ragweed contains not only serine protease activity but also cysteine protease activity like house dust mite (HDM) allergens. HDM allergens are important factors for the onset and exacerbation of AD. Previously, we have demonstrated cysteine protease of HDM allergens directly activate NLRP3 inflammasome in human keratinocyte and release mature IL-1beta and IL-18.

Protease Activity of Allergenic Pollen of Cedar, Cypress, Juniper, Birch and Ragweed

Pollen is an important trigger of allergic rhinitis, conjunctivitis, and/or asthma, and an exacerbating factor in atopic dermatitis. Although it is proposed that protease activity from allergen sources, such as mites, enhances allergenicity, little information is available on that from relevant allergenic pollens such as Japanese cedar and Japanese cypress pollens, which are the major cause of pollinosis in Japan. We analyzed the protease activities derived from allergenic pollen of Japanese cedar, Japanese cypress, and Rocky mountain juniper, which belong to the Cupressaceae/Taxodiaceae family, and white birch and short ragweed, using synthetic substrates and class-specific inhibitors. We found that the pollen of the three members of the Cupressaceae/Taxodiaceae family contained serine protease activity, that the pollen of white birch and short ragweed contained not only serine protease activity but also cysteine protease activity, that all five types of pollen tested contained at least one other type of serine protease, whose sensitivity to a serine protease-specific inhibitor was relatively low, and that the content and releasability of the pollen-derived proteases differed according to the plant families. Clinically relevant allergenic pollens tested in the present study can release serine and/or cysteine endopeptidases. Information on the spectrum of the endopeptidase activities from these allergenic pollen grains will be useful for investigating their contribution to the pathogenesis of allergies.

Survey of Food and Airborne Allergen-specific IgE Levels in a General Population of 3-year-old Japanese Children

Background data on the allergic constitutions of a general population of Japanese children may provide important information regarding environmental factors that contribute to the increased incidence of allergic diseases and suggest clues for their prevention. Serum samples were obtained from a general population of 3-year-old children (612 samples) in the Kanto area and Asahikawa city. The serum levels of total and specific IgE antibodies against food allergens (egg white, milk, soybean, wheat), indoor airborne allergens (house dust, mite, cat dandruff), and outdoor airborne allergens (Japanese cedar or white birch pollen allergens) were determined and analyzed, along with the results of a questionnaire regarding medical history, and allergy-related subjective symptoms. The mean total IgE level of all subjects was 34.7 IU/ml, while that for the Kanto and Asahikawa areas was 44.7 and 22.5 IU/ml, respectively. Twenty six percent of the 612 children were judged positive for indoor airborne allergen-specific IgE, and 6.7% were positive for food allergen-specific IgE. Cedar allergen-specific IgE was detected in 15.6% of the children living in the Kanto area. The total IgE level was strongly correlated with the number of allergens to which the child was sensitized. A relatively large number (28.4%) of 3-year-old children possessed allergen-specific IgE antibodies. The basic data obtained in the general population in these two areas of Japan will be valuable for further evaluations of environmental influences on allergic disease.

Allergy vaccine engineering: epitope modulation of recombinant Bet v 1 reduces IgE binding but retains protein folding pattern for induction of protective blocking-antibody responses.

Human type 1 immediate allergic response symptoms are caused by mediator release from basophils and mast cells. This event is triggered by allergens aggregating preformed IgE Abs bound to the high-affinity receptor (FcepsilonRI) on these cells. Thus, the allergen/IgE interaction is crucial for the cascade leading to the allergic and anaphylactic response. Two genetically engineered forms of the white birch pollen major allergen Bet v 1 with point mutations directed at molecular surfaces have been characterized. Four and nine point mutations led to a significant reduction of the binding to human serum IgE, suggesting a mutation-induced distortion of IgE-binding B cell epitopes. In addition, the mutated allergens showed a decrease in anaphylactic potential, because histamine release from human basophils was significantly reduced. Retained alpha-carbon backbone folding pattern of the mutated allergens was indicated by x-ray diffraction analysis and circular dichroism spectroscopy. The rBet v 1 mutants were able to induce proliferation of T cell lines derived from birch pollen allergic patients. The stimulation indices were similar to the indices of nonmutated rBet v 1 and natural Bet v 1 purified from birch pollen. The ability of anti-rBet v 1 mutant specific mouse IgG serum to block binding of human serum IgE to rBet v 1 demonstrates that the engineered rBet v 1 mutants are able to induce Abs reactive with nonmodified Bet v 1. rBet v 1 mutants may constitute vaccine candidates with improved efficacy/safety profiles for safer allergy vaccination.

Dispersal of pollen and the variation in number of patients prescribed medicine for allergies in Otaru

The number of patients prescribed medicine for allergies increased in May and September. Therefore, we suspected that the cause for the increase was pollen. Many kinds of pollen occur in Otaru, such as alder in April, Japanese black pine, white birch, acacia, larch in May, oak in June, and mugwort in September. The total number of pollen count of white birch was about 9 times that of mugwort, but the total number of patients prescribed Celestamine in the season of white birch pollen was about 0.8 times that of mugwort pollen. These results seen in Otaru differed from those in neighboring Sapporo. The coefficient of the correlation of the number of mugwort and white birch pollen and those of patients prescribed Celestamine were r = 0.304 and r = 0.766, respectively. We believe that making available information on pollen is very useful to improve the quality of life of patients.

Environmental pollution and pollen allergy — a possible link

Microbial pathogens and certain chemical compounds are capable of inducing a stress response in plants (shown for bean, parsley, pea, potato) as shown by transcription of genes coding for pathogenesis-related proteins (PRP). Bet v 1, the major allergen from pollen of white birch (Betula verrucosa), was found by molecular cloning, to be highly homologous to these PRPs, suggesting a function in the stress response of white birch. Although Bet v 1-encoding mRNA, that could be translated in vitro, was present in leaves, immature male and mature female inflorescences as well as in callus tissue, the Bet v 1 protein could be detected not at all or only in scarce amounts in these tissues. Leaves from birch trees from environmentally stressed areas showed enhanced expression of Bet v 1 antigen. In contrast, leaves from birch trees from an unpolluted area did not contain Bet v 1 in significant amounts. These data suggest that, in plants, stress conditions including environmental pollution may elicit enhanced expression of proteins that are potent inducers of an IgE response in man.

The gene coding for the major birch pollen allergen Betv1, is highly homologous to a pea disease resistance response gene.

Pollen of the white birch (Betula verrucosa) is one of the main causes of Type I allergic reactions (allergic rhinoconjunctivitis, allergic bronchial asthma) in Middle and Northern Europe, North America and the USSR. Type I allergies are a major threat to public health in these countries, since 10-15% of the population suffer from these diseases. BetvI, an allergenic protein with an Mr of 17 kd is a constituent of the pollen of white birch and is responsible for IgE binding in more than 95% of birch pollen allergic patients. Here, we report the complete nucleotide sequence and deduced amino acid sequence of a cDNA clone coding for the major pollen allergen (BetvI) of white birch. It is similar to the N-terminal peptide sequences of the allergens of hazel, alder and hornbeam (close relatives) but it has no significant sequence homology to any other known allergens. However, it shows 55% sequence identity with a pea disease resistance response gene, indicating that BetvI may be involved in pathogen resistance of pollen.