Expression of interleukin-17 in lung and peripheral blood of asthmatic rats and the influence of dexamethasone

The expression of interleukin-17 (IL-17) in lung and peripheral blood of asthmatic rats and the influence of dexamethasone, and the role of IL-17 in the pathogenesis of asthma were investigated. Thirty Sprague-Dawley (SD) adult rats were randomly divided into three groups (n=10 in each group): normal group, asthmatic group, and dexamethasone-interfered group. Rat asthmatic model was established by intraperitoneal (i.p.) injection of 10% ovalbumin (OVA) and challenge with 1% OVA via inhalation. Rats in dexamethasone-interfered group were pretreated with dexamethasone (2 mg/kg, i.p.) 30 min before each challenge. The expression of IL-17 protein in serum and bronchoalveolar lavage fluid (BALF) was detected by ELISA. The expression of IL-17 mRNA in peripheral blood mononuclear cells (PBMC) and BALF cells was semi-quantitatively detected by RT-PCR. The expression of IL-17 protein in serum and BALF of asthmatic rats was significantly elevated as compared with normal rats and dexamethsone-interfered rats (P<0.01), and there was significant difference between normal rats and dexamethsone-interfered rats (P<0.05). The expression of IL-17 mRNA in PBMC and BALF cells of asthmatic rats was markedly increased as compared with normal rats and dexamethsone-interfered rats (P<0.01), and significant difference was found between normal rats and dexamethsone-interfered rats (P<0.05). It was concluded that the expression of IL-17 was increased significantly in asthmatic rats and could be inhibited partly by dexamethasone, suggesting that IL-17 might play an important role in the pathogenesis of asthma as an inflammation regulation factor.