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The significance of in-depth post-translational modification (PTM) studies of pollen proteomes, when compared with studies on other aspects of pollution and altered pollen allergenicity, has not yet been determined; hence, little progress has been made within this field. Therefore, we created a comprehensive approach for the comparison of pollen from polluted and environmentally preserved areas. To examine the effects of long-term, in vivo pollen exposure to multiple source pollutants, Phleum pratense (Timothy grass) pollen samples were collected along a regional road in Kruševac, central Serbia and were compared with pollen samples from rural, environmentally preserved area over two consecutive pollination seasons. We combined the quantitative comparison of proteome expression profiles from in-solution and 2D-gels with unrestrictive in-depth quantitative PTM profiling using high resolution tandem mass spectrometry and the PEAKS 8.5 Suite platform. An increased phenolic content and release of sub-pollen particles was found in pollen samples from the polluted area, and significantly higher content of mercury, cadmium, and manganese. Antioxidative defense-related enzymes were significantly upregulated. Seven oxidative PTMs were significantly increased (methionine, histidine, lysine, and proline oxidation; tyrosine glycosylation, lysine 4-hydroxy-2-nonenal adduct, and lysine carbamylation) in pollen exposed to the chemical plant and road traffic pollution sources. Oxidative modifications affected pollen allergens, especially Phl p 6, with several different oxidative modifications. Quantitative, unrestricted, and detailed PTM searches using an enrichment-free approach was used for the first time to map extensive modifications in the pollen proteome, reflecting increased environmental oxidative stress, primarily caused by increased content of heavy metals in pollen. Acknowledgement to European Commission, under the Horizon2020, FoodEnTwin project.

Field-realistic exposure studies provide the most relevant assessment of the effects of the intensity and diversity of urban and industrial contamination on pollen structure and allergenicity. The significance of in-depth post-translational modification (PTM) studies of pollen proteomes, when compared with studies on other aspects of pollution and altered pollen allergenicity, has not yet been determined; hence, little progress has been made within this field.

Background. The presence of IgE reactivity to kiwi fruit and grass pollen allergens which could be caused by cross-reactivity has been detected in many patients with allergy. Proper identification of allergens as well as cross-reactive components is essential for understanding fruit and pollen associated hypersensitivity. Methods: Using the sera from the polysensitized patients with specific IgE to grass pollen and kiwi fruit we tested reactivity to both allergen sources. IgE reactivity was exhibited in 8 serum samples by immunoblot. A serum pool formed by 8 individual sera was used for the investigation of IgE crossreactivity. SDS-PAGE immunoblot-inhibition assay was performed by preincubation of the sera with meadow fescue pollen, kiwi fruit extract, and isolated 24 kDa kiwi protein. To determine the allergens of kiwi fruit extract, we performed 2D PAGE immunoblot. In order to detect the crossreactive components between two allergen sources, a specific IgE for the 24 kDa kiwi allergen was purified. Results. SDA-PAGE immunoblot meadow fescue pollen showed allergens ranging from 94 to 16 kDa, and kiwi fruit had 12 allergens ranging from 94 to 17 kDa. 2D-PAGE analysis revealed at least 15 spots in the kiwi extract and about 10 allergens. The most prominent allergen in 2D PAGE immunoblot was protein with 24 kDa and Pi 9.4-9.5. Using an affinity-purified specific IgE we found that the 24 kDa kiwi allergen shared IgE-reactive epitopes with the meadow fescue group 4 and allergen about 36 kDa. Crossreactivity between isolated 24 kDa kiwi allergen and Fes p 4 was confirmed by anti-grass group 4 moab 2D8. Conclusion: Our findings showed that fescue meadow pollen cross-sensitize to kiwi fruits. A 24 kDa kiwi glycoprotein represent potential major allergen, which share common epitopes with Fes p 4 and 36 kDa meadow fescue allergen.