Effects of Corticosteroids on Expression of Interleukin-18 in the Airway Mucosa of a Mouse Model of Allergic Rhinitis

Objectives: In this study, we aimed to investigate the release and response of interleukin (IL)-18 to steroid treatment in a mouse model of allergic rhinitis. Methods: BALB/c mice were sensitized systemically by intraperitoneal injection of ovalbumin and locally by ovalbumin inhalation. Dexamethasone sodium phosphate was given by intraperitoneal injection in the steroid treatment group. Symptom scores, eosinophil counts, and IL-18 concentrations in the nasal and lung lavage fluids were analyzed. Results: The symptom scores and eosinophil counts of the negative control and steroid treatment groups were significantly lower than those of the positive control group (p < .01). The mean IL-18 concentrations in the nasal lavage fluid were not significantly different among the three groups (56.68 ± 9.57, 63.39 ± 8.93, and 64.47 ± 6.83 pg/mL, respectively). The IL-18 concentrations in the lung lavage fluid were significantly different between the positive control group and the steroid treatment group (430.75 ± 154.54 and 69.94 ± 14.26 pg/mL, respectively, p = .028). Conclusions: The IL-18 concentration was found to be increased in the lung lavage fluid, but not in the nasal lavage fluid, in a mouse model of allergic rhinitis. Increased IL-18 concentrations returned toward the previous concentrations after steroid treatment. These results suggest that the roles of IL-18 may be different in the pathogenesis of allergic rhinitis and the pathogenesis of asthma.