The effects of an inhaled corticosteroid on oxygen radical production by bronchoalveolar cells after allergen or ozone in dogs

Abstract

Both ozone and allergen inhalation increase the capacity to produce oxygen radicals by bronchoalveolar lavage cells in dogs. The purpose of these studies was to determine whether inhaled corticosteroids inhibits these increases in oxygen radical production from bronchoalveolar lavage cells. Six random source dogs were studied after dry air or ozone inhalation (3 ppm, 30 min). Seven random source dogs were studied after diluent or allergen inhalation. The dogs inhaled budesonide (2.74 mg/day) or lactose powder, twice daily for 7 days before ozone and allergen. 90 min after ozone or dry air, and 24 h after Ascaris suum or diluent a bronchoalveolar lavage was carried out. Spontaneous luminol-enhanced chemiluminescence was measured from bronchoalveolar lavage cells (4 × 10⁶ cells) for 10 min, followed by a measurement of phorbol myristate acetate (PMA 2.4 μmol/I) stimulated chemiluminescence for 10 min. Both ozone and allergen inhalation caused an increase in PMA stimulated chemiluminescence (P < 0.05). Budesonide pretreatment inhibited ozone-induced (P < 0.008), but not allergen-induced PMA stimulated chemiluminescence (P > 0.90). Both ozone and allergen inhalation caused an increase in the bronchoalveolar lavage neutrophils. Budesonide pretreatment significantly inhibited the ozone-induced (P = 0.007), but not the ascaris-induced neutrophil influx (P = 0.93). These results demonstrate that ozone, but not allergen, stimulated oxygen radical release and neutrophil influx are attenuated by inhaled corticosteroids. This suggests that luminol-enhanced chemiluminescence from bronchoalveolar lavage cells measures oxygen radicals derived from neutrophils, and that ozone-and allergen-induced bronchoalveolar lavage neutrophilia are caused by different mechanisms.