Abstract
Purpose :
The prevalence of allergic diseases is rapidly increasing worldwide, and allergic conjunctivitis (AC) is one of the most common diseases in eye clinics. Beta-glucans (BG), extracted from yeast, fungi, bacteria, or mushrooms, are emerging as possible safe and effective immunotherapeutic drugs to modulate the immunologic response. However, the therapeutic potential of BG for AC and the underlying its mechanisms remain still unknown. This present study was designed to evaluate the efficacy of topically administrating BG to suppress the development of ovalbumin (OVA)-sensitized AC in a murine model.
Methods :
Seven- to eight-week-old BALB/c mice were sensitized with OVA and aluminum hydroxide via intraperitoneal injection. Two weeks later, mice were challenged by OVA eyedrops with vehicle or BG eyedrops once daily for 13 days. We evaluated clinical signs, the infiltration of inflammatory cells into conjunctiva, serum levels of OVA-specific IgE production, and Th2 cytokines secretion in vitro T cells assay through flow cytometry and ELISA. In addition, to evaluate inhibitory function of IL-10 CD4 T cells, CD4+ cells isolated from LNs and OVA-pulsed BMDCs were cocultured with anti–IL-10R blocking antibody or isotype control antibody, and then Th2 cytokines were measured with ELISA.
Results :
AC development and conjunctival infiltration of eosinophils (CD45+ Siglec-F+; p = 0.022 vs. vehicle) and mast cells (CD45+ c-kit+; p = 0.029 vs. vehicle) were significantly impaired with BG treatment. In addition, BG suppressed production of OVA-specific IgE in serum (p = 0.002 vs. vehicle) and Th2 cytokines in vitro T cell assays, such as IL-4 (p = 0.001 vs. vehicle) and IL-13(p = 0.018 vs. vehicle), compared to vehicle group. Interestingly, BG led to increase IL-10+ CD4 T cells population in draining LNs and suppressive levels of IL-4 and IL-13 on BG were reversed by blocking anti–IL-10R (p = 0.023 vs. isotype cotrol, p = 0.033 vs. isotype cotrol, respectively)
Conclusions :
Our results suggest that BG alleviate allergic conjunctivitis, indicated by suppressing Th2 response in draining LNs and inflammatory cells infiltration into conjunctiva. BG also increased population of IL-10-producing CD4+ T cells in draining LNs, which inhibited Th2 response. Therefore our results demonstrated new insight into the therapeutic potential of BG for allergic diseases including asthma or atopic dermatitis.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.