We have recently reported that disruption of nuclear erythroid 2 P45-related factor 2 (Nrf2) enhances susceptibility to airway inflammatory responses induced by low-dose diesel exhaust particles (DEP) in mice. C57BL/6 Nrf2 knockout (Nrf2-/-) mice and wild-type (Nrf2+/+) mice were further exposed to low-dose DEP for 7h/day, 5days/week, for a maximum of 8weeks. After exposure to DEP for 5weeks, allergic airway inflammation was generated in the mice by intraperitoneal sensitization with OVA followed by intranasal challenge. Nrf2-/- mice exposed to relatively low-dose DEP showed significantly increased percentage changes relative to the OVA alone group in terms of airway hyperresponsiveness (AHR) and inflammatory cells, levels of IL-5 and thymus and activation regulated chemokine (TARC) in bronchoalveolar lavage (BAL) fluid than did Nrf2+/+ mice. Lung tissues of Nrf2-/- mice after DEP exposure showed inflammatory cell infiltrates, and increased PAS staining-positive mucus cell hyperplasia. In contrast, the percentage changes relative to the OVA group in the reduced glutathione (GSH)/oxidized glutathione (GSSG) ratio in whole blood was higher in Nrf2+/+ mice than in Nrf2-/- mice. By using Nrf2-/- mice, it was shown for the first time that relatively low-dose DEP exposure induces oxidant stress, and that host anti-oxidant responses play a key role in the development of DEP-induced exacerbation of allergic airway inflammation.
- Allergic airway inflammation
- Anti-oxidant stress
- Low-dose diesel exhaust particles
- Nrf2-knockout mouse