Effects of Quercetin Treatment on Epithelium-derived Cytokines and Epithelial Cell Apoptosis in Allergic Airway Inflammation Mice Model

Quercetinis a dietary flavonoid which has anti-inflammatory effects. This study aimed to evaluate the influence of quercetinon histopathological aspects and airway epithelium in allergic airway inflammationmice model. Twenty-eight BALB/c mice were randomly divided into four groups: Group I (control), Group II (untreated mice with allergic airway inflammation), Group III (allergic airway inflammation quercetin-treated [16mg/kg/day]), Group IV (allergic airway inflammationdexamethasone-treated [1mg/kg/day]). Ovalbumin was administered intraperitoneally and via inhalation to achieve allergic airway inflammationmice model and treatments were also given intraperitoneally. Epithelium thickness, subepithelial smooth muscle thickness, number of mast and goblet cells, and basement membrane thickness were examined on samples isolated from lung. Immunohistochemical evaluationof lung tissues was performed using IL-25, IL-33, thymic stromal lymphopoietin(TSLP), terminal deoxynucleotidyl transferase-mediated dUTP nick endlabeling (TUNEL) and cysteine-dependent aspartate-specific proteases(caspase)-3 antibodies. IL-4, IL-25, IL-33, TSLP were quantified in bronchoalveolar lavage (BAL) and OVAspecific IgE levels was measured in serum by standard ELISA protocols. IL-25, IL-33, thymic stromal lymphopoietin(TSLP) and cysteine-dependent aspartate-specific proteases (caspase)-3. Quercetintreatment led to lower epithelial thickness, subepithelial smooth muscle thickness, goblet and mast cell numbers compared to untreated mice with allergic airway inflammation( p <0.05). However, quercetintreatment was not effective on improving basal membane thickness. Immunohistochemical scores of IL-25, IL-33, TSLP, caspase-3 and TUNEL were lower in quercetin-treated mice t compared to untreated mice with allergic airway inflammation( p <0.05). IL-4, IL-25, IL-33, TSLP levels in BAL and OVA-specific IgE in serum were lower in quercetintreated mice compared to untreated mice ( p <0.05). These findings suggest that quercetinimproves chronic histopathological changes except basal membrane thickness in lung tissue and its beneficial effects on inflammationmight be related to modulating epithelium derived cytokines and epithelial apoptosis.