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
Abstract
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,
RORt, 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 RORt in
inflammatory cells.