Polycyclic aromatic hydrocarbons aggravate antigen-induced nasal blockage in experimental allergic rhinitis

It has been hypothesized that air pollution has played a role in the increase in allergy prevalence. However, it remains unclear what exact roles are played by polycyclic aromatic hydrocarbons (PAHs), which are encountered in the environment in the form of air pollution, in allergic rhinitis. Thus, we examined whether benzo(a)pyrene (BaP) and 1-nitropyrene (1-NP), representative PAHs, aggravate allergic rhinitis symptoms, using a guinea-pig model. Sensitized animals were repeatedly challenged by inhalation of Japanese cedar pollen once a week. BaP or 1-NP was daily and intranasally administered for 2 weeks (short-term treatment) or for 22 weeks from the time before the sensitization period (long-term treatment). The short-term treatment affected neither nasal blockage nor sneezing induced by antigen. In contrast, the long-term treatment aggravated the antigen-induced nasal blockage that was induced 7 weeks after the start of the treatment with BaP or 1-NP. This aggravation continued during the intranasal treatment with PAH. However, neither sneezing nor Cry j 1-specific IgE antibody production was affected even by the long-term treatment. In conclusion, the long-term treatment with BaP and 1-NP can aggravate allergic rhinitis. The mechanisms underlying this aggravation are not associated with production of Cry j 1-specific IgE.