Tectochrysin, a
flavonoid compound, can be isolated from
propolis, Alpinia oxyphylla Miq, and Lychnophora markgravii. This study evaluated the efficacy of
tectochrysin in the treatment of shrimp
tropomyosin (ST)-induced mouse
asthma. Mice were sensitized with intraperitoneal (i.p.) injection of ST together with
aluminum hydroxide as an adjuvant to establish a mouse model of
asthma. Mice were i.p.-treated daily with
tectochrysin.
IgE levels in plasma, Th2
cytokines from both bronchoalveolar lavage (BAL) fluid and splenocytes, and CD200R on basophils in peripheral blood were measured. Histological analyses of lung tissues and accumulation of leukocytes in BAL fluid were performed. Lung
eosinophil peroxidase,
catalase and
glutathione peroxidase activities were examined. ST was found to markedly increase eosinophilic
inflammation and Th2 response in mice.
Tectochrysin treatment reduced the level of
IgE in plasma, the percentage of eosinophils in total white blood cells in peripheral blood, the total number of cells in BAL fluid, and
eosinophil peroxidase activity in lung tissues.
Tectochrysin attenuated ST-induced infiltration of eosinophils and epithelial mucus secretion in lung tissues and suppressed the overproduction of Th2
cytokines (IL-4 and IL-5) in BAL fluid.
Tectochrysin also attenuated Th2
cytokine (IL-4 and IL-5) production from
antigen-stimulated murine splenocytes in vitro, decreased the expression of CD200R on basophils in peripheral blood of asthmatic mice and inhibited
IL-4 secretion from
IgE-sensitized RBL-2H3 cells. In addition,
tectochrysin enhanced
catalase and
glutathione peroxidase activities in lung tissues. Our findings demonstrate that TEC ameliorates allergic airway
inflammation by suppressing Th2 response and oxidative stress.