ABSTRACT
Quercetin, a flavonoid found in a wide variety of plants, has been studied for possible health benefits, and it has been found to have potent anti-oxidant, anti-viral and anticancer effects. Although quercetin is also reported to act as an antihistamine and an anti-inflammatory through the suppression of mast cell activation, the influence of quercetin on eosinophil activation is not fully understood. The present study, therefore, was undertaken to examine the influence of quercetin on eosinophil activation, especially chemokine production by using an in vitro cell culture technique. Eosinophils (5×10(5) cells/ml) obtained from Mesocestoides corti-infected mice were stimulated with 200 ng/ml stem cell factor in the presence of different concentrations of quercetin for 24 h. Chemokine, eotaxin, regulated on activation normal T cell expressed and secreted and macrophage inflammatory protein-1ß, levels in culture supernatants were examined by enzyme-linked immunosorbent assay (ELISA). We also examined the influence of quercetin on chemokine mRNA expression and transcription factor, nuclear factor kappa B and activator protein 1, activation by real-time reverse transcription polymerase chain reaction and ELISA, respectively. Treatment of eosinophils with quercetin at more than 4.5 µM caused a significant decrease in chemokine levels in culture supernatants. Quercetin also suppressed transcription factor activation in 4 h-cultured cells and mRNA expression of chemokine in 12 h-cultured cells, which were increased by stem cell factor stimulation. These results may suggest that quercetin inhibits eosinophil activation, especially chemokine production, and results in inhibition of the development of eosinophilic inflammatory responses.
Subject(s)
Chemotactic Factors/biosynthesis , Eosinophils/drug effects , Eosinophils/metabolism , Quercetin/pharmacology , Animals , Antioxidants/pharmacology , Cells, Cultured , Chemokines/biosynthesis , Chemokines/genetics , Chemotactic Factors/genetics , Eosinophils/immunology , Gene Expression Regulation/drug effects , Male , Mice , RNA, Messenger/genetics , Stem Cell Factor/pharmacology , Transcription Factors/metabolismABSTRACT
The influence of quercetin on eosinophil functions was examined in vitro and in vivo. The first set of experiments was undertaken to examine whether quercetin could suppress eosinophilia and IgE hyperproduction induced by Mesocestoides corti infection in BALB/c mice. The number of peripheral blood eosinophils and IgE levels were examined 21 days after infection. Oral administration of quercetin for 21 days could not suppress both peripheral blood eosinophilia and IgE hyperproduction, even when 20.0 mg/kg quercetin was used for treatment. The second part of the experiment was designed to examine the influence of quercetin on eosinophil activation induced by SCF stimulation in vitro. Eosinophils were obtained from M. corti-infected mice and stimulated with SCF in the presence of various concentrations of quercetin for 24 h. The addition of quercetin into cell cultures could suppress eosinophil activation induced by SCF stimulation as assessed by measuring the contents of RANTES, MIP-1 ß , ECP, and MBP in culture supernatants. The minimum concentration of quercetin which caused significant suppression of factor secretion was 5.0 µ M. These results may suggest that quercetin will be a good candidate for the supplement on the management of eosinophil-mediated diseases, such as allergic rhinitis and asthma.
