Abstract: 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.