The Effect Of Quercetin On A Murine Model Of Allergic Rhinitis

Background: Allergic rhinitis (AR) is caused by IgE-mediated immediatehypersensitivity and ultimately progress as chronic nasal inflammation. Quercetinbelongs to the subgroup of flavonols and is the most often found in onions, apples,grapes, red wine and green tea. This flavonoid confirmed several biological activitiesin the airways. Our study aimed to investigate whether quercetin has treatment effectson nasal symptoms of allergic rhinitis model in mice and the mechanism.Materials and Methods: Male BALB/c mice were divided into five groups randomly:the control group (Ctr group), which received saline; allergic rhinitis group (ARgroup), which were sensitized by administering an intraperitoneal injection ofovalbumin (OVA) and aluminium hydroxide hydrate gel (alum), and challenge wasperformed by instilling OVA into the bilateral nasal cavities; loratadine group (Loragroup), the low concentration of quercetin group (Low group) and the highconcentration of quercetin group (High group), which were both sensitized andchallenged by ovalbumin, and administered loratadine, low concentration of quercetin(50mg/kg) and high concentration of quercetin (100mg/kg) respectively. Nasalrubbing and sneezing were monitored after the last administration. In addition, serumOVA-specific immunoglobulin E (IgE) antibody, and interleukin (IL)-4, Interferon(IFN)-γ in nasal lavage fluid were determined by ELISA kits respectively. SplenicCD4+CD25+Foxp3+regulatory T cells (Tregs) and IL-17cells (Th17) were examinedby flow cytometry to investigate the mechanism involved.Results: A significant inhibition of nasal symptoms-sneezing and nasal rubbing insensitized mice was observed after repeated oral administration of quercetin.Additionally, quercetin alleviated both OVA-specific IgE antibody and IL-4production; however, it had no effect on IFN-γ levels in nasal lavage fluid. Finally,quercetin inhibited the airway inflammation of allergic rhinitis by regulating thebalance between Treg and Th17.Conclusion: These results furtherly indicate that quercetin may be effective in the relief of symptoms of allergic rhinitis through reducing OVA-specific IgE and IL-4levels, and moduating the ratio of spleen CD4+CD25+Foxp3+cells and CD4+IL-17+cells. Therefore, our results demonstrate that the balance of Treg/Th17can also play arole in the pathogenesis of allergic rhinitis.