title: High environmental ozone levels lead to enhanced allergenicity of birch pollen.
abstract: BACKGROUND
  Evidence is compelling for a positive correlation between climate change, urbanisation and prevalence of allergic sensitisation and diseases. The reason for this association is not clear to date. Some data point to a pro-allergenic effect of anthropogenic factors on susceptible individuals.
  
  
  OBJECTIVE
  To evaluate the impact of urbanisation and climate change on pollen allergenicity.
  
  
  METHODS
  Catkins were sampled from birch trees from different sites across the greater area of Munich, pollen were isolated and an urbanisation index, NO2 and ozone exposure were determined. To estimate pollen allergenicity, allergen content and pollen-associated lipid mediators were measured in aqueous pollen extracts. Immune stimulatory and modulatory capacity of pollen was assessed by neutrophil migration assays and the potential of pollen to inhibit dendritic cell interleukin-12 response. In vivo allergenicity was assessed by skin prick tests.
  
  
  RESULTS
  The study revealed ozone as a prominent environmental factor influencing the allergenicity of birch pollen. Enhanced allergenicity, as assessed in skin prick tests, was mirrored by enhanced allergen content. Beyond that, ozone induced changes in lipid composition and chemotactic and immune modulatory potential of the pollen. Higher ozone-exposed pollen was characterised by less immune modulatory but higher immune stimulatory potential.
  
  
  CONCLUSIONS
  It is likely that future climate change along with increasing urbanisation will lead to rising ozone concentrations in the next decades. Our study indicates that ozone is a crucial factor leading to clinically relevant enhanced allergenicity of birch pollen. Thus, with increasing temperatures and increasing ozone levels, also symptoms of pollen allergic patients may increase further.
authors.affiliation: ZAUM - Center of Allergy & Environment, Member of the German Center for Lung Research (DZL), Technische Universität München/Helmholtz Center, Munich, Germany.
authors.forename: Isabelle
authors.initials: I
authors.lastname: Beck
authors.forename: Susanne
authors.initials: S
authors.lastname: Jochner
authors.forename: Stefanie
authors.initials: S
authors.lastname: Gilles
authors.forename: Mareike
authors.initials: M
authors.lastname: McIntyre
authors.forename: Jeroen T M
authors.initials: JT
authors.lastname: Buters
authors.forename: Carsten
authors.initials: C
authors.lastname: Schmidt-Weber
authors.forename: Heidrun
authors.initials: H
authors.lastname: Behrendt
authors.forename: Johannes
authors.initials: J
authors.lastname: Ring
authors.forename: Annette
authors.initials: A
authors.lastname: Menzel
authors.forename: Claudia
authors.initials: C
authors.lastname: Traidl-Hoffmann
mesh_terms: D000393:Air Pollutants / Q000032:analysis*; D000485:Allergens / Q000276:immunology*; D029662:Betula / Q000276:immunology*; D015232:Dinoprostone / Q000378:metabolism; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D007975:Leukotriene B4 / Q000378:metabolism; D010126:Ozone / Q000032:analysis*; D011058:Pollen / Q000276:immunology*; D012882:Skin Tests
chemical_list: D000393:Air Pollutants; D000485:Allergens; D007975:Leukotriene B4; D010126:Ozone; D015232:Dinoprostone