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

Abstract

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.

Effects of NO<sub>2</sub> on Inflorescence Length, Pollen/Seed Amount and Phenolic Metabolites of Common Ragweed (<i>Ambrosia artemisiifolia</i> L.)

“…These data indicate that individual stress will differentially affect the flavonoid composition. As we did not find significant differences in the total flavonoid amount, it is unlikely that there is a direct effect of flavonoids on IgE recognition, as elevated NO 2 resulted in a higher IgE recognition in immunoblots [16]. However, flavonoids can play a modulating role on immunity and inflammation [46] and may influence membrane translocation of allergens [47].…”

“…Briefly, (treatment) [16]. For each population morphological data like inflorescence length, the pollen and seed amount was measured.…”

“…It has been shown that elevated CO 2 concentrations result in an increase of A. artemisiifolia growth and pollen production [9] [10] [11] [12]. In addition to climate change parameters, air pollution might also influence the allergenicity of A. artemisiifolia pollen [13] [14] [15] [16]. However, the fumigation of A. artemisiifolia plants with 80 ppb O 3 did not alter the pollen amount [12].…”

“…However, treatment of pollen from four different tree species with moderate NO 2 concentrations (40 -300 ppb) resulted in greater immunoglobulin E (IgE) recognition by immunodetection [23] [27]. Pollen isolated from A. artemisiifolia that was fumigated with realistic NO 2 concentrations (80 ppb) also showed a higher IgE recognition [16]. Similarly NO 2 -fumigated pollen of P. pratense stimulated the production of chemokines by an increased Th2-cell response in human cells [28].…”

Direct effects of insecticides on common ragweed-implications for natural enemy exclusion trials

“…The allergenicity of pollen of this species is known to be altered by other abiotic stressors, such as drought, aerial pollutants and elevated levels of CO 2 , NO 2 and O 3 . [25][26][27][28][29] We therefore specifically tested whether the application of the three selected broad-spectrum insecticides has direct effects on i) plant traits, ii) seed and pollen numbers, and iii) the allergenicity of pollen of common ragweed.…”