Topical Administration of β-1,3-Glucan to Modulate Allergic Conjunctivitis in a Murine Model.

Abstract

Recent studies on β-1,3-glucan (BG), a cell wall component of a variety of fungi, yeasts, and bacteria, demonstrated that it affects the balance of Th1/Th2 immune responses. We therefore determined whether topical application of BG modulates ocular allergy in a murine model. We sensitized 7- to 8-week-old BALB/c mice once with ovalbumin (OVA) and aluminum hydroxide via intraperitoneal injection. Mice were rested for 2 weeks and then challenged by instillation of OVA eye drops once daily for 13 days. We administered BG eye drops 5 minutes after OVA challenge once daily. Clinical signs were measured, the infiltration of eosinophils and mast cells into conjunctiva was assessed with flow cytometry, and the serum levels of OVA-specific IgE production and Th2 cytokines after in vitro stimulation of T cells in draining lymph nodes (LN) were determined. Mice treated with BG showed attenuated allergic conjunctivitis, as indicated by clinical signs and decreased production of serum OVA-specific IgE. In addition, BG treatment led to decreased infiltration of CD45+ immune cells, eosinophils, and mast cells into the conjunctiva, compared with the mice treated with vehicle alone (control mice). Administration of BG suppressed Th2 cytokine production in in vitro T-cell assays partially through the induction of interleukin (IL)-10-producing CD4 T cells in draining LNs. Taken together, these results suggest that BG is capable of stimulating IL-10-producing CD4+ T cells and suppressing both the Th2 response in draining LNs and conjunctival eosinophil infiltration. We therefore demonstrated the therapeutic potential of topical BG administration for allergic conjunctivitis.