Roots of Lithospermum erythrorhizon Alleviated Ovalbumin-Induced Allergic Rhinitis and IgE-triggered Degranulation of RBL-2H3 Cells

Abstract

Lithospermum erythrorhizon (L. erythrorhizon) root is used in traditional medicine for its anti-inflammatory, antibacterial, and antioxidant properties. However, no studies have examined its impact on allergic rhinitis (AR). Here, we explored the protective effects of L. erythrorhizon in immunoglobulin E (IgE)-stimulated RBL-2H3 cells and in an ovalbumin (OVA)-induced AR mouse model. In the latter, we examined nasal mucosal inflammation, allergen-specific cytokine production, and histological changes to the nasal mucosa. In the mouse model, oral administration of an ethanol extract of L. erythrorhizon (LE) led to a marked reduction in rubbing and sneeze frequency, a significant decrease in serum OVA-specific IgE and IgG1 levels, and a significant increase in the IgG2a/IgG1 ratio. LE also reduced expression of interleukin (IL)-4, IL-5, and IL-13 in nasal lavage fluid (NALF), and suppressed inflammatory cell infiltration and epithelial degradation in nasal tissues. In IgE-stimulated RBL-2H3 cells, LE suppressed release of degranulation markers such as β-hexosaminidase and histamine. Based on these findings, we suggest that LE may ameliorate OVA-induced AR by regulating mast cell-mediated inflammatory responses.