Oral administration of Forsythiasides-rich extract from Forsythiae fructus decreases the IgE production through suppressing Th2 response in shrimp protein-sensitized BALB/c mice

Abstract

Background: IgE-mediated allergic diseases are characterized by an overreaction of type 2 response which promotes B cell differentiation and IgE production via Th2 cytokines. Forsythiae Fructus, a well-known traditional Chinese medicine, has been clinically used for relieving IgE-mediated type I allergy by continuous treatment for several days. Purpose: We aimed to investigate the effect of continuous oral administration with Forsythiasides-rich extract (FRE) from Forsythiae Fructus on type 2 response and the underlying mechanism in shrimp protein (SP)-sensitized mice. Study design and methods: We established a SP-sensitized mice model and investigated effect of FRE both in vivo and ex vivo. Serum total IgE (tIgE), specific IgE (sIgE), mouse mast cell protease 1 (mMCP-1) and supernatant Th2 cytokines (IL-4, IL-5 and IL-13) were determined by ELISA. The cell viability was examined by MTS assay. Results: Continuous oral administration of FRE could significantly lower the levels of serum tIgE, sIgE and mMCP-1 in SP-sensitized mice. Ex vivo study indicated that a single treatment of FRE could potently suppress the release of Th2 cytokines (IL-4, IL-5 and IL-13) in isolated mesenteric lymph nodes cells and splenocytes of SP-sensitized mice in a concentration-dependent manner. Conclusion: FRE can suppress Th2 cytokines (IL-4, IL-5 and IL-13) to decrease the production of IgE in SP-sensitized mice. In view of its another ability to stabilize mast cells, Forsythiae Fructus is reasonably suitable for treating IgE-mediated allergic diseases.

Keywords

• Forsythiae Fructus
• IgE production
• Th2 response
• Type I allergy