Suppression of airway inflammation by Illicium verum and trans-anethole

Abstract

To develop an antiasthmatic agent, Illicium verum and its major components were evaluated for their ability to suppress airway inflammation. Furthermore we have studied the effects of trans-anethole compound on Treg cell-mediated suppression [1]. Asthma was induced in BALB/c mice by systemic sensitization to ovalbumin (OVA) followed by intratracheal, intraperitoneal, and aerosol allergen challenges. Illicium verum and its major components were orally administered for 4 weeks. We investigated their effects on airway hyperresponsiveness, pulmonary eosinophilic infiltration, various immune cell phenotypes, cytokine & cytospin measurements in bronchoalveolar lavage (BAL), Th2 cytokine production, OVA-specific IgE production, Th1/Th2 cytokine production, lung histology and immunofluorescence analysis in this mouse model of asthma [2]. Illicium verum and trans-anethole significantly (p < 0.05) inhibited OVA-induced increases in total cell counts, eosinophil counts, and IL-4, IL-5, and IL-13 levels recovered in bronchoalveolar lavage fluid in OVA-sensitized mice. trans-Anethole further substantially (p < 0.05) reduced the total IgE, eotaxin 2 levels, and CCR3 expression of BAL fluid. trans-Anethole also substantially (p < 0.05) increased the Foxp3 and TGF-b1 mRNA expression of BAL fluid. Histological studies showed that trans-anethole dramatically inhibited eosinophilia, and infiltration of lymphocytes in lung tissues. These results suggest that the anti-inflammatory and anti-asthmatic effects of Illicum verum and trans-anethole are exerted through upregulation of regulatory T cells.