Abstract
BACKGROUND The IL-17 superfamily, which mediates cross-talk between the adaptive and innate immune systems, has been associated with severity of asthma. The role of miRNAs in the disease has been paid much attention. To explore the roles of IL-17 in asthma and the relationship between IL-17 and miRNAs, we used a model of severe asthma driven by chronic respiratory exposure to house dust mite (HDM) exposure in wild type and IL-17KO mice, followed with miRNA profiling assays and analysis.METHODS Male and female C57BL/6 mice (6-8 weeks old) and IL-17KO mice (C57BL/6 background) were exposed to purified HDM extract intranasally for 5 days/week for 5 consecutive weeks. Sterile saline was used as the control. The parameters including airway responsiveness, inflammatory cells in bronchoalveolar lavage fluid (BALF), airway smooth muscle bundle, collagen deposition, and cytokine levels in BALF were examined. The miRNA profile of mouse lung tissue was analyzed by microarray assays. The dysregulation of miRNA related to IL-17 and asthma was validated by qRT-PCR. The in vitro cell culture experiment was performed to confirm the relationship between IL-17 and selected miRNA. The regulation of miRNA on predicted target gene was validated by administration of miRNA mimics. RESULTS The expression of IL-17A significantly increased in wild type (WT) mice with HDM exposure compared to the control mice. IL-17 deficiency did not reduce airway hyper responsiveness (AHR) induced by HDM exposure. In comparison to HDM-exposed WT mice, BALF neutrophils in IL-17KO mice were significantly decreased. In WT mice, HDM exposure led to increased expression of IL-4 and KC, which was significantly decreased in IL-17KO mice. Furthermore, under HDM exposure, significantly less airway smooth muscle mass and collagen deposition was found in IL-17KO mice compared to WT mice. In the dysregulated miRNAs, the decreased expression of miR-365-3p in HDM-exposed WT mice was validated, and its expression recovered in IL-17KO mice. Furthermore, miR-365-3p was decreased in mouse alveolar epithelial cells by IL-17 treatment. The transfection of miR-365-3p mimics decreased the expression of predicted target gene ARRB2.