Traffic related air pollutants induced elevated platanus pollen allergenicity – A study in three cities of Iberian Peninsula

Abstract

Background Air pollution aggravates asthma and respiratory allergies evoking higher incidence and/or symptoms worsening in heavily polluted areas. Road traffic is one of the major sources of air pollutants on urban environments. Pollen from Platanus hispanica, dispersed in early spring, contacts closely with air gaseous pollutants generated by automobile traffic, such as nitrogen oxides and ozone, whose effects on its allergenic properties are still unclear. The objective of this work was to evaluate allergenicity in P. hispanica pollen from Lisbon, Toledo and Madrid in relation to local air pollutant levels. Method Pollen was harvested in 2019 in Lisbon, Toledo and in four locations within Madrid (Retiro, Pz. Eliptica, Ens. Vallecas and M. Alvaro), in the proximity of Air Quality Monitoring Stations. NOx, O3, PM10 and PM2.5 concentrations were obtained from open access databases and were compared between stations. Pla a 1 allergen was quantified by ELISA from pollen protein extracts. Western blot was used to compare pollen Pla a 1 relative content according to location and immunoblot using pooled sera from allergic individuals was used for IgE recognition patterns. Results NO and NO2 levels were higher in Pz.Elíptica, reaching a maximum of 111 and 108 mg/m3, respectively. Retiro station registered the lower values for both pollutants (max. 30 and 61 mg/m3, respectively). Daily mean O3 concentration varied between 20-80, 20-68 and 16-65 mg/m3 in Retiro, Ens. Vallecas and Pz.Elíptica, commonly higher in the Retiro station during the whole period. Pla a 1 concentration varied between 1.2±0.2 and 2.9±0.2 μg Pla a 1/mg protein and was significantly different in Retiro (higher O3 levels) and Pz Eliptica (higher NOx levels) samples. Semi-quantitative analysis by western-blot revealed an equivalent profile. IgE-recognition pattern showed several bands differentially detected in pollen extracts, with band 51±1 KDa and 37±1 KDa more intense in Retiro, M. Alvaro (both Madrid) and Toledo. Conclusion Taken together, these results show that pollution pockets with distinct characteristics could be found within Madrid city influencing pollen specific allergenic profiles. A better understanding of the effects of environmental pollutants on the allergenic characteristics of pollen is essential to understand the phenomenon of increased respiratory allergy incidence in urban spaces.