Immunosuppressive effect of sinomenine in an allergic rhinitis mouse model

Allergic rhinitis (AR) is a chronic allergic airway disease that has become a significant global public health issue. Sinomenine (SN), a natural phytochemical found in Sinomenium acutum, showed anti-inflammatory and immunosuppressive effect in previous studies. In order to explore the role of SN in the treatment of AR, mice were sensitized and challenged by ovalbumin (OVA) to establish an AR mouse model. SN was administered to AR mice orally, and compared with dexamethasone treatment as a positive control. Nasal symptoms and histopathological changes were used to evaluate the effect of SN treatment in the AR mice model. In addition, the levels of anti-OVA specific IgE and various cytokines in the serum were measured by enzyme-linked immunosorbent assay, while the levels of transforming growth factor-β (TGF-β) in the mucosa were also detected by western blot analysis and reverse transcription-quantitative polymerase chain reaction. AR mice that received SN treatment had reduced symptom scores and milder eosinophil infiltration. The serum levels of anti-OVA specific IgE and interleukin-4 significantly decreased following SN treatment. Furthermore, TGF-β expression levels in the serum and nasal mucosa tissue in AR mice increased when compared with those in AR mice without treatment. In conclusion, SN treatment alleviated the symptoms of AR in mice and had an immunosuppressive effect on AR, which may result from the upregulation of TGF-β.