Dexamethasone reduces IL-17 and Tim-3 expression in BALF of asthmatic mice

This study investigated the expression of interleukin-17 (IL-17) and T cell immunoglobulin mucin and domain-containing molecule-3 (Tim-3) in bronchoalveolar lavage fluid (BALF) of asthmatic mice and the effect of dexamethasone (DEX) on these factors. Thirty-six mice were randomly divided into three groups: normal group, asthmatic group and DEX group. The mouse model of asthma was established by sensitization with ovalbumin in both the asthmatic and DEX groups. The levels of IL-6, IL-10, IL-17 and TGF-β were measured in BALF by enzyme-linked immunesorbent assay (ELISA). The mRNA expression level of Tim-3 was detected by reverse transcription polymerase chain reaction (RT-PCR). The ratio of Tim-3+CD4+ cells to total CD4+ cells in BALF was determined by flow cytometry. Differential inflammatory cells in BALF were detected. The correlations among IL-17, IL-6, IL-10, Tim-3 and inflammatory cells were analyzed. The results showed that the levels of IL-17, IL-6 and Tim-3 were substantially increased and the IL-10 level decreased in BALF in the asthmatic mice, which was significantly reversed by DEX treatment. IL-17 expression was positively correlated with IL-6 and Tim-3 expression and the number of inflammatory cells but negatively with IL-10 expression. These results indicate that the increased expression of IL-17 and Tim-3 in BALF may be implicated in the occurrence and development of asthmatic inflammation; the mechanism by which DEX suppresses asthmatic airway inflammation involves down-regulation of IL-17 and Tim-3 levels.