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Saikosaponin D inhibits nasal inflammation by regulating T-box protein expressed in T cells, GATA-3, and RORγt in a murine model of allergic rhinitis


      Aim: Saikosaponin D (SSD) is a commonly prescribed agent against inflammatory diseases in Asian countries. However, the anti-allergic inflammatory effect of SSD and its role in allergic rhinitis (AR) model is well known. In the present study, we investigated the anti-allergic and anti-inflammatory effects of SSD on the ovalbumin (OVA)-induced AR model. Methods: AR was induced in BALB/c mice by sensitization and treatment with OVA. Different concentrations of SSD and dexamethasone (Dex) were administered. The mice were then evaluated for the presence of nasal mucosal inflammation, the production of allergen-specific cytokine responses, as well as the histology of nasal mucosa. Results: Following SSD treatment, the nasal symptoms and the inflammation of nasal mucosa were significantly ameliorated. During AR, administering SSD to the AR mice appeared to balance the Type 1 helper T cells (Th1) to Th2 cytokine ratio by increasing and decreasing the percentage of Th1 and Th2 cytokines, respectively. Meanwhile, SSD also appeared to markedly inhibit Th17 cytokines and their related transcription factor, RORt, whereas the Th1 cytokines and their related transcription factor, T-bet, was significantly increased in NALF and lung homogenates in OVA-induced AR mice. Notably, SSD also reduced the levels of OVA-specific Immunoglobulin E (IgE) and IgG1, and increased the levels of IgG2a in serum. Conclusion: This study demonstrated that SSD has a significant anti-allergic inflammatory effect in the nasal cavity. SSD may represent an alternative therapeutic approach for the treatment of patients with AR through the regulation of T-bet, GATA-3, and RORt in inflammatory cells.