Marker allergens and panallergens in tree and grass pollen allergy

Outdoor airborne allergens: Characterization, behavior and monitoring in Europe

Aeroallergens or inhalant allergens, are proteins dispersed through the air and have the potential to induce allergic conditions such as rhinitis, conjunctivitis, and asthma. Outdoor aeroallergens are found predominantly in pollen grains and fungal spores, which are allergen carriers. Aeroallergens from pollen and fungi have seasonal emission patterns that correlate with plant pollination and fungal sporulation and are strongly associated with atmospheric weather conditions. They are released when allergen carriers come in contact with the respiratory system, e.g. the nasal mucosa. In addition, due to the rupture of allergen carriers, airborne allergen molecules may be released directly into the air in the form of micronic and submicronic particles (cytoplasmic debris, cell wall fragments, droplets etc.) or adhered onto other airborne particulate matter. Therefore, aeroallergen detection strategies must consider, in addition to the allergen carriers, the allergen molecules themselves. This review article aims to present the current knowledge on inhalant allergens in the outdoor environment, their structure, localization, and factors affecting their production, transformation, release or degradation. In addition, methods for collecting and quantifying aeroallergens are listed and thoroughly discussed. Finally, the knowledge gaps, challenges and implications associated with aeroallergen analysis are described.

Plant Stress Scenarios Differentially Affect Expression and IgE Reactivity of Grass Group-1 Allergen (β-Expansin) in Maize and Rice Pollen

Grass pollen is among the most common outdoor aeroallergens eliciting pollen allergies throughout the world. Grass group-1 allergen or β-expansin is recognized as a major pollen allergen, particularly in the grass family Poaceae. Expression of β-expansin has been shown to be dynamic and can be influenced by environmental stresses. This study evaluated the relative expression of β-expansin and IgE-binding ability of crude pollen extract protein of rice and maize under three different stress conditions: flood, salt, and drought. After 1 week of treatments, anthers containing pollen were collected followed by RNA extraction and cDNA synthesis. To evaluate relative expression, qRT-PCR was performed using specific primers for β-expansin and reference genes. Physiological characteristics of treated and untreated maize and rice: plant height; fresh weight of anthers; number of inflorescences, anthers, and pollen grains were also recorded. To assess IgE-binding ability of proteins in rice pollen extracts, soluble crude proteins were extracted and IgE immunoblot and ELISA were performed using serum samples from grass-allergic subjects and healthy control donors. Results showed that plant height, fresh weight of anthers, number of inflorescences, anthers, and pollen grains of both maize and rice decreased significantly under drought stress conditions, but not in other conditions. Expression of β-expansin in pollen of rice showed an apparent increase in all stress treatments relative to control samples. In contrast, a significant decrease of β-expansin expression was detected in maize pollen under all stress-treated conditions. IgE-reactive protein bands from rice pollen extract proteins were ~30 kDa, as expected of the grass-group 1 protein. The intensity of IgE-reactive protein bands and the level of IgE to rice pollen proteins showed significant differences among stress conditions. In conclusion, environmental stresses—flood, salt, and drought, can elicit a change of β-expansin expression and IgE reactivity to grass group-1 pollen allergens. Changes in expression level of this gene likely reflected its importance during stress. However, the response is highly dependent on different schemes employed by each plant species.

Allergenic risk assessment of urban parks: Towards a standard index

Allergenicity indices are a powerful tool to assess the health hazard posed by urban parks to pollen allergic subjects. Nonetheless, only few indices have been developed and applied to urban vegetation in the last decade, and they were never compared nor standardised over the same dataset. To address this issue, in this paper the two best-known allergenicity indices, the Urban Green Zones Allergenicity Index (I_UGZA) and the Specific Allergenicity Index (SAI), have been calculated for the same park (the Botanical Garden of Bologna), collecting vegetation data through both systematic sampling and arboreal census. The results obtained with the two data collection methods were comparable for both indices, indicating systematic sampling as a reliable approximation of the total census. Besides, the allergenic risk resulted moderate to high according to SAI, and very low according to I_UGZA. Since SAI does not consider the total volume of the vegetation, it was deemed less reliable than I_UGZA in evaluating the allergenicity of an enclosed green space.

Fungal spores and pollen in particulate matter collected during agricultural activities in the Po Valley (Italy)

Airborne particulate matter (PM) containing fungal spores and pollen grains was sampled within a monitoring campaign of wheat threshing, plowing and sowing agricultural operations. Fungal spores and pollen grains were detected and identified on morphological basis. No studies were previously available about fungal spore and pollen content in agricultural PM in the Po Valley. Sampling was conducted in a Po Valley farmland in Mezzano (Ferrara, Italy). The organic particles collected were examined by scanning electron microscopy with energy dispersive X-ray spectrometer. Fungal spores and pollen grains were identified when possible at the level of species. The most frequent components of the organic particles sampled were spores of Aspergillus sp., which could represent a risk of developing allergies and aspergillosis for crop farmers.

Clinical Relevance of IgE to Profilin and/or Polcalcin in Pollen-Sensitized Patients

BACKGROUND

Component-resolved diagnostics is gaining importance in allergy diagnostics. Allergen extracts contain components with different rates of prevalence and clinical relevance, which can be subdivided at molecular level into major and minor allergens. Clinical complaints are usually triggered by major allergens, while the role of sensitization to the panallergens profilin and polcalcin still remains unclear.

METHODS

Eighty-six patients from southern Bavaria with sensitization to the panallergens profilin (Bet v 2/Phl p 12) and/or polcalcin (Bet v 4/Phl p 7) were examined in regard to their sensitization to the 4 main botanic denominations Betulaceae, Oleaceae, Poaceae and Asteraceae by skin prick test and measurement of specific immunoglobulin E antibodies to natural allergen extracts as well as major allergen components rPhl p 1/5, rBet v 1, rOle e 1 and nArt v 1. Sensitization was rated as clinically relevant or irrelevant depending on anamnesis or intranasal allergen challenge.

RESULTS

Regarding the 4 botanic denominations, there was no significant difference in the incidence of sensitization to the panallergens profilin, polcalcin or both. The sensitization pattern does not alter when subdividing the cohort into clinically relevant and silent sensitization. We did not find clinically symptomatic sensitization to panallergens without cosensitization to a major allergen.

CONCLUSIONS

Our results suggest that sole sensitization to panallergens seems to have no clinical relevance in allergic rhinoconjunctivitis. Clinical complaints seem to be triggered manly by major allergens. Thus, component-resolved allergy diagnostics is crucial in the diagnosis and treatment of polysensitized patients.