Chestnut
Summary
Chestnut trees (Castanea spp.) are distributed across the Northern hemisphere, particularly in Spain and the wider Mediterranean region. Chestnut pollen is produced in large quantities and disperses over long distances. Castanea sativa pollen is a recognized allergen causing rhinoconjunctivitis and asthma. Chestnut pollen is part of the birch-homologous group of allergens, although recent evidence for cross-reactivity with other tree pollens is inconclusive.
Epidemiology
Worldwide distribution
Allergy to chestnut pollen represents a major cause of pollinosis in sub-Mediterranean areas.
Route Of Exposure
Main
The main route of exposure is inhalation.
Clinical Relevance
Chestnut pollen allergy is associated with allergic rhinoconjunctivitis and asthma.
Diagnostics
Chestnut pollen may be sampled using a vacuum air sampler such as the Burkard spore trap.
Prevention And Therapy
Allergen immunotherapy
Immunotherapy with the reference allergen Bet v 1 (birch pollen) induced highly variable repertoires of cross-reactive IgG1 and IgG4 antibodies to other members of the birch-homologous group, including chestnut pollen. Current data suggest that chestnut pollen allergy does not show sufficient immunological cross-reactivity to respond successfully to immunotherapy.
Prevention strategies
Avoidance
Allergenic pollen calendars are a simple method for forecasting chestnut pollen counts, as demonstrated using data from eight collection stations in South Korea over 10 years. Artificial neural networks (a type of computational learning) have proved to be a valid tool for predicting Castanea pollen concentration for one day ahead and, less reliably, for two and three days ahead of exposure.
Cross-Reactivity
The European Medicines Agency includes Castanea sativa in the birch-homologous group of tree pollens. The major allergen of chestnut pollen (Cas s 1) demonstrates a 75% (N-terminal) amino acid sequence homology with Bet v 1, the major allergen of birch pollen. The earlier pollen seasons for hazel and alder may act to prime patients for birch pollen allergy, followed by allergic responses to beech and chestnut pollen.
In a study of 17 Bet v 1-sensitized, birch pollen-allergic patients, all subjects displayed IgE reactivity with the most common isoforms of Cas s 1. However, a larger study examining 397 birch-allergic patients before and after treatment with standardized quality tree sub-lingual immunotherapy (SLIT) tablets did not find significant IgE or IgG4 cross-reactivity to chestnut, suggesting that chestnut pollen is not immunologically part of the birch-homologous group.
References
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- López-Orozco R, Hernández-Ceballos MÁ, Galán C, García-Mozo H. Atmospheric Pathways and Distance Range Analysis of Castanea Pollen Transport in Southern Spain. Forests. 2020;11(10):1092.
- Shin JY, Han MJ, Cho C, Kim KR, Ha JC, Oh JW. Allergenic Pollen Calendar in Korea Based on Probability Distribution Models and Up-to-Date Observations. Allergy Asthma Immunol Res. 2020;12(2):259-73.
- Biedermann T, Winther L, Till SJ, Panzner P, Knulst A, Valovirta E. Birch pollen allergy in Europe. Allergy. 2019;74(7):1237-48.
- CABI. Castanea (chestnut) Wallingford, UK2021 [cited 2021 15.11.21]. Available from: https://www.cabi.org/isc/datasheet/16586.
- Hirschwehr R, Jäger S, Horak F, Ferreira F, Valenta R, Ebner C, et al. Allergens from birch pollen and pollen of the European chestnut share common epitopes. Clin Exp Allergy. 1993;23(9):755-61.
- Grilo JR, Kitzmüller C, Aglas L, Sánchez Acosta G, Vollmann U, Ebner C, et al. IgE-cross-blocking antibodies to Fagales following sublingual immunotherapy with recombinant Bet v 1. Allergy. 2021;76(8):2555-64.
- Würtzen PA, Grønager PM, Lund G, Gupta S, Andersen PS, Biedermann T, et al. Simplified AIT for allergy to several tree pollens-Arguments from the immune outcome analyses following treatment with SQ tree SLIT-tablet. Clin Exp Allergy. 2021;51(2):284-95.
- Matricardi PM, Kleine-Tebbe J, Hoffmann HJ, Valenta R, Hilger C, Hofmaier S, et al. EAACI Molecular Allergology User's Guide. Pediatr Allergy Immunol. 2016;27 Suppl 23:1-250.
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