Intranasal fluticasone propionate inhibits allergen induced bone marrow eosinophilia in mice

Local corticosteroids are currently the most efficient safe anti-allergic treatment, which attenuate eosinophilic tissue inflammation through several mechanisms. We evaluated the effect of local airways corticosteroid on repeated allergen exposure-induced bone marrow activation and airway eosinophilia using the number of eosinophils in bone marrow, bronchoalveolar lavage fluid (BALf) and airways tissue as study end-points. Male BALB/c mice were sensitized by intraperitoneal injections of aluminum-precipitated ovalbumin (OVA) on two different days (5 days apart). Eight days after the second sensitization, the animals were challenged intranasally with OVA or phosphate-buffered saline (PBS) on 5 consecutive days. Concomitantly with challenges mice were treated with fluticasone propionate or respective vehicle. OVA exposures induced a significant increase in eosinophil numbers in bone marrow, BALf and airways tissue (P<0.005). Treatment with fluticasone propionate significantly reduced the increase of absolute number of mature bone marrow eosinophils (P=0.014) and showed a tendency towards decrease in the immature bone marrow eosinophil number (P=0.057) compared to controls. However, fluticasone propionate had no significant effect on BALf and airways tissue eosinophils (P=0.28 and 0.07, respectively). In this murine allergy model intranasal corticosteroid reduced number of bone marrow mature eosinophils, but did not significantly affect airways cell populations.