OBJECTIVETo study the effect of budesonide (BUD) on RORγt expression in the pulmonary tissue of asthmatic mice and mechanisms of BUD in the treatment of asthma.

METHODSBlab/c asthmatic mouse model was induced by ovalbumin (OVA). Thirty female mice were randomly divided into three groups: control, asthmatic and BUD-treated. IL-17 levels in bronchoalveolar lavage fluid (BALF) and serum were measured using ELISA. Total and differential cell counts in BALF were measured. Airway inflammation was evaluated by hematoxylin and eosin staining. IL-17 mRNA and RORγt mRNA expression were measured by reverse transcription-polymerase chain reaction (RT-PCR).

RESULTSRORγt mRNA and IL-l7 levels in the asthmatic group were significantly higher than in the control group (P<0.01). BUD treatment significantly decreased RORγt mRNA and IL-l7 levels compared with the asthmatic group (P<0.01). Compared with the control group, total, neutrophil and eosinophil cell count in BALF increased significantly in the asthmatic group (P<0.01). After BUD treatment, counts of total, neutrophil and eosinophil cells in BALF were significantly reduced (P<0.01) and were similar to in the control group. Inflammatory reactions in the respiratory tract were significantly alleviated in the BUD treated group.

CONCLUSIONSRORγt and IL-l7 levels in the pulmonary tissue of asthmatic mice increase and this may be associated with the pathogenesis of asthma. BUD can inhibit RORγt and IL-17 and thus reduces lung inflammation.