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Background: Ambrosia artemisiifolia L. is one of the most important sources of allergenic pollen in many regions of the world. Its health impact increased over the last decades and is expected to further increase in consequence of climate change. However little information is available on the specific role played by temperature on allergy rising. The aim of this work was to evaluate the effect of temperature on A. artemisiifolia growth, flowering and pollen allergenicity, the major plant functional traits influencing the prevalence and severity of pollinosis. Results: Plants were grown in controlled conditions at three thermal regimes: "Low" (LT: 18-14 °C light-dark), "Intermediate" (IT: 24-20 °C light-dark) and "High" (HT: 30-26 °C light-dark). During plant development, plant vegetative and reproductive morpho-functional traits were measured and, at the end of plant life-cycle, mature pollen was collected and analyzed for its allergenic properties by slot blot, 1D- and 2D-western blot (by using a pool of sera from ragweed-allergic patients) and liquid chromatography-tandem mass spectrometry. A. artemisiifolia showed a great development plasticity leading to a broad temperature tolerance. Shoot architecture, growth rate, number of male inflorescence and pollen allergenicity were temperature-responsive traits. Pollen allergenicity increased in parallel with temperature and differences were related to allergen synthesis and Amb a 1-IgE-binding. Flavonoids whose concentration in pollen decreased with the increase of temperature, were recognized as the cause of the negligible Amb a 1-IgE binding in LT pollen. Conclusions: Results show that temperature governs plant development and pollen allergenicity influencing the temporal and spatial magnitude of subject exposure to allergens.

Background: Ambrosia artemisiifolia L. is one of the most important sources of allergenic pollen in many regions of the world. Its health impact increased over the last decades and is expected to further increase in consequence of climate change. However little information is available on the specific role played by temperature on allergy rising. The aim of this work was to evaluate the effect of temperature on A. artemisiifolia growth, flowering and pollen allergenicity, the major plant functional traits influencing the prevalence and severity of pollinosis. Results: Plants were grown in controlled conditions at three thermal regimes: "Low" (LT: 18-14 °C light-dark), "Intermediate" (IT: 24-20 °C light-dark) and "High" (HT: 30-26 °C light-dark). During plant development, plant vegetative and reproductive morpho-functional traits were measured and, at the end of plant life-cycle, mature pollen was collected and analyzed for its allergenic properties by slot blot, 1D- and 2D-western blot (by using a pool of sera from ragweed-allergic patients) and liquid chromatography-tandem mass spectrometry. A. artemisiifolia showed a great development plasticity leading to a broad temperature tolerance. Shoot architecture, growth rate, number of male inflorescence and pollen allergenicity were temperature-responsive traits. Pollen allergenicity increased in parallel with temperature and differences were related to allergen synthesis and Amb a 1-IgE-binding. Flavonoids whose concentration in pollen decreased with the increase of temperature, were recognized as the cause of the negligible Amb a 1-IgE binding in LT pollen. Conclusions: Results show that temperature governs plant development and pollen allergenicity influencing the temporal and spatial magnitude of subject exposure to allergens.

4399, open, The alien plant Ambrosia artemisiifolia L. (common ragweed) is one of the main allergenic species in Europe and especially in Northern Italy, where it has become the second cause of respiratory allergy in the last two decades. In a context of climate changing, it is very important to understand what factors the allergenicity of pollen, which is primarily determined by the presence of major allergens, depends on. Specifically it should be very interesting to define if allergenicity is dependent on environmental conditions, acting as non-heritable epigenetic factors, or on heritable elements. The objective of this thesis was to study the allergenicity variation among pollen samples from different ragweed plants/populations and to identify the mechanisms and factors contributing to the variability. To this aim, seeds from ragweed Canadian, French and Italian populations, were collected and used to grow plants both “in standard natural conditions”, where the temperature (T), humidity (H) and light (L) changed during plant development, and in “controlled conditions” where environmental parameters (T, H, L) were maintained constant all the plant vital cycle long. The two applied grow conditions were applied to identify and understand the influence of heritable and non-heritable factors (epigenetic environmental factors) on pollen allergenicity. The mechanisms underlying the change in allergenicity were investigated by studying the qualitative and quantitative variations of the isoforms of the major ragweed allergen Amb a 1 with proteomic techniques. Before this experiment, ragweed populations were genetically characterized to define the origin of Italian populations and to confirm that the genetic variability is very high within populations but low among them. The results of these analyses indicated that ragweed Italian populations have a North America origin as the French ones and that all the populations investigated show, as expected, a high genetic variability among i, No, embargoed_20190215, Ciappetta, S, Ciappetta, S

Negli ultimi decenni si è assistito ad un progressivo incremento nella frequenza delle patologie allergiche, tanto da considerarle, attualmente, come la “nuova epidemia” del XXI secolo. Questo notevole ed inarrestabile aumento ha attirato l’attenzione della comunità scientifica e pubblica, rendendo le allergie una priorità a livello globale. Tra le malattie allergiche la pollinosi è certamente la manifestazione più comune e diffusa, soprattutto nei paesi industrializzati; è difficile stabilire la prevalenza assoluta delle pollinosi ma in Italia si stima che fino al 15% della popolazione ne sia interessata. A questo proposito, in Italia, ed in particolare nell’area piemontese e lombarda, Ambrosia artemisiifolia L. è la specie che desta maggiori preoccupazioni anche a causa della sua veloce espansione, tanto da essere considerata la seconda causa di pollinosi nel milanese. Ambrosia artemisiifolia L è una pianta erbacea invasiva alloctona a ciclo annuale, originaria del Nord America e accidentalmente introdotta in Europa in seguito all’importazione di carichi di semi di interesse agricolo all’inizio del secolo scorso. A causare allergie è l’allergene maggiore di ambrosia, Amb a 1 con le sue isoforme; proteine appartenenti alla famiglia delle pectato liasi (Amb a 1.1, Amb a 1.2, Amb a 1.3, Amb a 1.4, Amb a 1.5), che possono essere espresse nel polline. Rimane da appurare se tutte le isoforme sono espresse contemporaneamente nel polline di singole piante e quale sia l’attività immunologica delle singole isoforme. Da dati bibliografici risulta che l’ambrosia produce popolazioni verosimilmente caratterizzate da un’alta variabilità genetica tra gli individui e risulta quindi importante studiare le singole piante per comprendere i fattori genetici ed ambientali che determinano l’aggressività del polline. In questo contesto, stiamo valutando la variabilità genetica inter ed intra-popolazione dell’ambrosia in relazione alle isoforme di Amb a 1 e al loro potenziale

Background: Sensitization to weed pollen allergens at the molecular level is not fully understood. We studied IgE reactivity to the major mugwort allergen Art v 1 in relation to allergens from other weed pollen and cross-reactive components in mugwort-sensitized subjects. Methods: Art v 1 and Amb a 1 were affinity purified and coupled to experimental ImmunoCAP (R) tests. Samples from North Europe (n = 50), South Europe (n = 19) and North America (n = 41) were analyzed for IgE against mugwort pollen, weed allergen components, pan-allergens and cross-reactive carbohydrate determinants (CCDs). Results: The prevalence of IgE reactivity (> 0.35 kU(A)/l) to Art v 1 was significantly higher in samples from North Europe than in those from North America. IgE to Amb a 1 was more common in North America than in North and South Europe, while IgE to Par j 2 was common in South Europe, less common in North America, and absent in North Europe. IgE to Art v 3 in mugwort-allergic patients was more common in North Europe than in South Europe and North America, while IgE to Sal k 1 was similar between the areas. Subjects with an Art v 1/mugwort-specific IgE ratio < 0.5 had more often IgE to Amb a 1, profilin, polcalcin and CCDs than subjects with a ratio > 0.5. Conclusions: Mugwort-sensitized subjects have different IgE reactivity profiles to weed allergens, reflecting their exposure to various pollens. Subjects with a low ratio between the IgE levels to Art v 1 and mugwort have a diverse IgE reactivity profile, indicating a role for cross-reactive allergens in their mugwort sensitization.