Abstract: Objective To observe the inhibitory effect and the relative mechanisms of dexamethasone(DEX) on airway inflammation in mouse models with allergic asthma. Methods BALB/c mice were randomly divided into control group, asthma group, and dexamethasone group. The mice in the asthma group were subcutaneously injected with ovalbumin (OVA)/aluminum hydroxide mixture on day 0, 7, 14 and nebulized with 1% OVA suspension for 20 minutes on day 21 and 22. The mice in the dexamethasone group were given intraperitoneal injection of dexamethasone 3 hours before each inhalation based on the asthma group. The airway resistance of mice was measured at the end of the last aerosol inhalation, the cells in bronchoalveolar lavage fluid (BALF) were counted by Wright-Giemsa staining. The concentration of inflammatory factors in BALF was measured by ELISA. The protein expression of NLRP3 and IL-1β were detected by immunohistochemistry (IHC), and lung histopathological analysis was performed. Results Compared with the control group, the airway hyperresponsiveness (AHR) of mice in the asthma group was significantly enhanced; The numbers of eosinophils and neutrophils in BALF were significantly increased (P＜0.01); IL-5, IL-6, IL-18 and IL-1β expression in BALF were significantly increased (P＜0.01); The expression of NLRP3 and IL-1β in lung tissue was enhanced as shown by IHC result. Compared with the asthma group, AHR of mice in the dexamethasone group was significantly reduced; The expression levels of IL-18 and IL-1β were also significantly decreased(P＜0.01); The protein expressions of NLRP3 and IL-1β in the lung tissue were decreased; The pathological histology analysis showed inflammatory infiltration in lung tissue from the dexamethasone group was significantly reduced (P＜0.01). Conclusions Dexamethasone suppresses NLRP3 inflammasome activation induced by OVA, decreases inflammatory factors expression and airway hyperresponsiveness, thereby effectively alleviates the airway inflammation of asthmatic mice.

Key words: bronchial asthma, NLRP3, IL-1β, dexamethasone, airway inflammation