Influence of Dexamethasone on IL-25 and IFN-γ in Bronchoalveolar Lavage Fluid of Asthmatic Mice

Objective To investigate the mechanism of therapeutic action of dexamethasone on asthmatic mice by detecting the levels of IL-25 and IFN-γ in bronchoalveolar lavage fluid( BALF). Methods Balb /c mice with SPF grade were randomly divided into normal control group,asthma group and dexamethasone group. Asthma group and dexamethasone group were sensitized and challenged with ovalbumin( OVA). Dexamethasone group was intraperitoneally injected with dexamethasone one hour before challenging. The mice were executed 24 hours after the last challenge,and the HE stained pathological sections of the right lung were made. Pathological sections of lung were observed. BALF in the left lung was also collected. The total white blood cell count and absolute eosinophile( EOS) count were observed,and the percentage of EOS was calculated. The levels of IL-25 and IFN-γ were measured with ELISA,and correlation analyses were made. Results The counts of total white blood cell and EOS,and the percentage of EOS were significantly higher in the asthma group than in the normal control group and dexamethasone group( P 0.05). No differences were found between the normal control group and dexamethasone group. The IL-25 level was higher in the asthma group than in the normal control group and dexamethasone group( P 0. 05),and its level in the dexamethasone group was also higher than that in the normal control group. The IFN-γ level was lower in the asthma group than in the normal control group and dexamethasone group( P 0. 05),while there was no significant difference between the normal control group and dexamethasone group. IL-25 was negatively correlated with IFN-γ in each group. Conclusion Part of the mechanisms of dexamethasone acting on asthma are related to its inhibition on the pulmonary inflammation and promotion on the expression of IFN-γ,and possible inhibition of IL-25 expression.