[Effect of dexamethasone on expression of interleukin-21 and phospho-STAT3 in a murine model of chronic asthma].

OBJECTIVE: To investigate the effects of dexamethasone on the expression of interleukin-21 (IL-21) and phospho- STAT3 (p-STAT3) in a murine model of chronic asthma. METHODS: Thirty-three female BALB/C mice were randomly divided into control group, asthmatic group and dexamethasone-treated group (n=11). In the latter two groups, asthmatic models were established by ovalbumin administration. The cells in the broncho-alveolar lavage fluid (BALF) were counted and classified. The airway inflammation was evaluated by HE staining, and the expressions of IL-21 and p-STAT3 in the lung tissue were detected by immunohistochemistry and Western blotting. RESULTS: The total cell number and lymphocyte number in the BALF were significantly higher in asthmatic group than in the control group and dexamethasone group (P/0.01). Compared with the control group, the asthmatic group showed significantly increased protein expressions of IL-21 and p-STAT3 (P<0.05), which were reduced by dexamethasone intervention (P/0.05). CONCLUSION: Dexamethasone can inhibit the expression of IL-21 and p-STAT3 in the murine model of chronic asthma, suggesting the importance of IL-21/STAT3 signaling pathway in the therapeutic mechanisms of dexamethasone for asthma.