Preventive Effect of Bupleurum chinense on Nasal Inflammation via Suppressing T Helper Type 2, Eosinophil and Mast Cell Activation

Abstract

Bupleurum chinense is distributed in East Asia and has been used as a traditional herbal medicine for more than a thousand years. Though B. chinense has been reported to have immunomodulatory, anti-inflammatory, anti-oxidant, hepato-protective, antipyretic, analgesic and antifibrotic effects, its specific effect on allergic rhinitis disease has not been clarified. In this study, we investigated the anti-allergic and anti-inflammation effects of B. chinense extract (BCE) in an ovalbumin (OVA)-induced allergic rhinitis (AR) mouse model. Oral administration of BCE in a dose-independent manner regulated the balance of Th1/Th2/Treg cell differentiation in AR mice. Accordingly, BCE attenuated the expression of Th2-related cytokines such as IL-4, IL-5 and IL-13 in nasal lavage fluid (NALF) and nasal tissue and up-regulated the secretion of Th1/Treg cells including IL-10, IL-12 and IFN- $\gamma$ . Also, BCE inhibited the formation and migration of eosinophils to the nasal mucosa and NALF, as well as suppressed CCL24, an eosinophil-specific chemoattractant in NALF. The levels of anti-OVA specific IgE and anti-OVA specific IgG1 were decreased, and as a result, the allergic response was attenuated by BCE via inhibiting mast cells accumulation in nasal mucosa and serum histamine release. The nasal allergy symptoms, nasal mucosal swelling, epithelial barrier disruption and mucus hyperplasia were obviously ameliorated. These results suggest that BCE may have therapeutic potential for treating allergic rhinitis through modulating the accumulation and activation of important leukocytes in the immune system such as Th1, Th2, Treg, eosinophils and mast cells.

Keywords: Allergic Rhinitis; Eosinophils; Mast Cells; Nasal Epithelium; Th1/Th2/Treg Cytokines.