Subpollens delivery of Platanus acerifolia pollen allergen Pla a3 and nucleic acid into lungs and cells

Exposure to green space and pollen allergy symptom severity: A case-crossover study in Belgium

BACKGROUND

The prevalence of pollen allergy has increased due to urbanization, climate change and air pollution. The effects of green space and air pollution on respiratory health of pollen allergy patients are complex and best studied in spatio-temporal detail.

METHODS

We tracked 144 adults sensitized to Betulaceae pollen during the tree pollen season (January-May) of 2017 and 2018 and assessed their spatio-temporal exposure to green space, allergenic trees, air pollutants and birch pollen. Participants reported daily symptom severity scores. We extracted 404 case days with high symptom severity scores and matched these to 404 control days. The data were analyzed using conditional logistic regression with a 1:1 case-crossover design.

RESULTS

Case days were associated with exposure to birch pollen concentration (100 grains/m³) [adjusted odds ratio 1.045 and 95% confidence interval (1.014-1.078)], O₃ concentration (10 μg/m³) [1.504 (1.281-1.766)] and PM₁₀ concentration (10 μg/m³) [1.255 (1.007-1.565)] on the day of the severe allergy event and with the cumulative exposure of one and two days before. Exposure to grass cover (10% area fraction) [0.655 (0.446-0.960)], forest cover (10% area fraction) [0.543 (0.303-0.973)] and density of Alnus (10%) [0.622 (0.411-0.942)] were protective for severe allergy, but only on the day of the severe allergy event. Increased densities of Betula trees (10%) were a risk factor [unadjusted OR: 2.014 (1.162-3.490)].

CONCLUSION

Exposure to green space may mitigate tree pollen allergy symptom severity but only when the density of allergenic trees is low. Air pollutants contribute to more severe allergy symptoms. Spatio-temporal tracking allows for a more realistic exposure assessment.

Characterization of allergenicity of Platanus pollen allergen a 3 (Pla a 3) after exposure to NO2 and O3

Pollen allergens, widely present in the atmosphere, are the main cause of seasonal respiratory diseases that affect millions of people worldwide. Although previous studies have reported that nitrogen dioxide (NO₂) and ozone (O₃) promote pollen allergy, the specific biological processes and underlying mechanisms remain less understood. In this study, Platanus pollen grains were exposed to gaseous pollutants (NO₂ and O₃). We employed environmental electron microscopy, flow cytometry, western blot assay, enzyme-linked immunoassay, ultraviolet absorption spectrometry, circular dichroism, and protein mass spectrometry to characterise the subpollen particles (SPPs) released from pollen grains. Furthermore, we determined the immunogenicity and pathogenicity induced by Platanus pollen allergen a 3 (Pla a 3). Our results demonstrated that NO₂ and O₃ could damage the pollen cell membranes in SPPs and increase the amount of Pla a 3 allergen released into the atmosphere. Additionally, NO₂ and O₃ altered the structure of Pla a3 protein through nitrification and oxidation, which not only enhanced the immunogenicity of allergens but also increased the stability of the protein. In vivo analysis using an animal model indicated that NO₂ and O₃ greatly aggravated pollen-induced pneumonia. Thus, our study provides guidance for the prevention of pollen allergic diseases.

Flow cytometric analysis of pollen and spores: An overview of applications and methodology

Pollen grains are the male gametophytes in a seed-plant life cycle. Their small, particulate nature and crucial role in plant reproduction have made them an attractive object of study using flow cytometry (FCM), with a wide range of applications existing in the literature. While methodological considerations for many of these overlap with those for other tissue types (e.g., general considerations for the measurement of nuclear DNA content), the relative complexity of pollen compared to single cells presents some unique challenges. We consider these here in the context of both the identification and isolation of pollen and its subunits, and the types of research applications. While the discussion here mostly concerns pollen, the general principles described here can be extended to apply to spores in ferns, lycophytes, and bryophytes. In addition to recommendations provided in more general studies, some recurring and notable issues related specifically to pollen and spores are highlighted.

Studies on relationships between air pollutants and allergenicity of Humulus Scandens pollen collected from different areas of Shanghai

Pollen pollution and allergy are becoming prominent issues in China. However, few studies on pollinosis have been reported. As an allergen in the atmosphere, allergenic Humulus scandens pollen was collected from four districts of Shanghai, including Wusong (WS), Jiading (JD), Xujiahui (XJH) and Songjiang (SJ). The mass concentrations of SO₂, NO₂, O₃, PM_10, and PM_2.5 (particulate matter with air dynamic diameter less than 10 and 2.5 µm, respectively) near the four sampling sites were also recorded during Humulus scandens pollen season. The allergenicity of the Humulus scandens pollen was assessed by using of a rat model and enzyme linked immunosorbent assay (ELISA). Relationships between the allergenicity and air pollutants were correlated. Our results demonstrated that the biological viability of the pollens collected from the four districts exhibited no significant differences. ELISA and dot blotting results further demonstrated that the serum of sensitized rats exhibited much higher immune-reactive response than that of control groups. Western blotting showed that the 15 KD (1KD = 1000 dalton) proteins of Humulus pollen led to the allergic response. The allergenic intensity of Humulus pollen protein from different samples followed the pattern: WS > JD > XJ > SJ. There was a negative relationship between the allergenicity of Humulus pollens and PM₁₀ (R = -0.99) / PM_2.5 (R = -0.73), and a positive relationship with O₃ (R = 0.92). These data clearly showed that PM₁₀ and PM_2.5 could enhance Humulus pollen protein release, and O₃ could aggravate the allergenicity of the Humulus pollen.